DESC:FIELD OF INVENTION
[001] The present disclosure broadly relates to multimetallic compounds. Particularly, the present disclosure relates to multimetallic compounds having redox active ligands and devices comprising the multimetallic compounds. 5 BACKGROUND OF INVENTION
[002] Memory devices are electrical switches that maintain an internal resistance state based on applied voltage. These devices possess several performance attributes that may surpass those of traditional integrated circuit technology. These devices will serve as the foundation for the upcoming computing architectures, 10 including neuromorphic computing. With increasing growth of communication sectors and use of electronic apparatuses, the demand for memory devices has increased on an exponential scale. Generally, non-volatile memory devices are used in electronic apparatuses, wherein the recorded data is not erased when power sources are turned off. 15
[003] A wide range of materials such as inorganic oxide materials, 2D materials, polymers, and various molecular systems have been explored to date as active components in memory devices, which implement ‘in-memory computing’. As may be understood, in-memory computing facilitates storage and processing of data in one unit. This is advantageous as compared with conventional computing systems, 20 wherein which processing necessitates separate units between which data exchange is to be implemented. Such data exchange (which may be very frequent depending on the extent of processing required) imposes considering computational overheads. However, in-memory computing avoids such situations and would generally be preferable for computationally extensive processes. Currently, 25 commercialised memory devices generally comprise oxide-based materials which require a high voltage/current for forming and setting processes. This requirement of high voltage/current reduces their ability to provide high density memory devices.
[004] Organic memory devices have recently been extensively researched for the 30 electronic active materials due to their advantages such as chemical or mechanical
2
flexibility, economic fabrication, and processing compatibility, in comparison to their inorganic counterparts. However, due to limited information on switching behaviours and ambiguity in structure–property relationships of these organic materials-based devices, most of these devices often face challenges. These problems result in wastage of energy and compromised reproducibility. 5 Furthermore, reliability and accuracy are also a concern that has to be addressed for such in-memory systems. Specifically, challenges in relation to such devices pertain to is to store the data reliably and accurately in as many number of states as possible, which has been found to be challenging when memory devices are made from presently known compounds. This arises due from the molecular systems which 10 may allow only limited thermodynamic (electronic or geometric or conformational) states in a reasonable energy range, thereby limiting the computational capability of the memory devices.
[005] Therefore, in order to address the above-mentioned problems, designing organic-based devices with multiple redox states is desirable at every levels. 15 Incorporating organometallic or metallic complexes as active materials, has become an advantageous strategy via employing metallic and/or ligand centric redox states to result in the material as a whole to possess non-volatile capacitive states.
[006] Therefore, there is a need to develop advanced memory devices having organic-metallic materials possessing multiple redox states and fast switching 20 efficiency are demand of the hour. SUMMARY OF THE INVENTION
[007] In an aspect of the present disclosure, there is provided a compound of Formula I its salts, stereoisomers, or salts thereof, 25
(La)mMx(Lb)nM’y(Lc)o
Formula I
wherein La, Lb, and Lc are independently selected from azo, N3, halogen, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, or combinations thereof; M at each 30 occurrence, may be identical or different, selected from transition metals; M’ at each 3
occurrence, may be identical or different, selected from transition metals; m is in a range of 1 to 3; n is in a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; and y is in a range of 1 to 6.
[008] In another aspect of the present disclosure, there is provided a device comprising: a. at least two electrodes; and b. a molecular film comprising a top 5 surface and a bottom surface, wherein the molecular film comprises a compound as disclosed herein, and the molecular film is electrically associated with the at least two electrodes
[009] In yet another aspect of the present disclosure, there is provided a process for preparation of the device as disclosed herein, the process comprising: a. 10 obtaining a solution of a compound as disclosed herein, in the presence of a solvent; b. forming a molecular film of the solution on a bottom electrode; and c. assembling the top electrode upon the top surface of the molecular film to obtain the device.
[0010] In yet another aspect of the present disclosure, there is provided a use of the compound as disclosed herein, or the device as disclosed herein, in electronic, 15 electrical, sensory or computing appliances.
[0011] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the 20 disclosed subject matter, nor is it intended to be used to limit the scope of the disclosed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012]
The following drawings form a part of the present specification and are 25 included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0013] Figure 1 depicts the schematic representation of the device, in accordance with an embodiment of the present disclosure. 30 4
[0014] Figure 2 illustrates the cyclic voltammetry profile of the Compound 2 recorded in acetonitrile (CH3CN) using saturated calomel electrode (SCE) as the reference electrode, in accordance with an embodiment of the present disclosure.
[0015] Figure 3 depicts the current-voltage (I-V) characteristics demonstrating the resistive switching behavior of devices fabricated using the compound 2, in 5 accordance with an embodiment of the present disclosure.
[0016] Figure 4 depicts the cyclic voltammetry profile of Compound 4 recorded in acetonitrile (CH3CN) using SCE as the reference electrode, in accordance with an embodiment of the present disclosure.
[0017] Figure 5 depicts the cyclic voltammetry profile of the Compound 8 recorded 10 in acetonitrile (CH3CN) using SCE as the reference electrode, in accordance with an embodiment of the present disclosure.
[0018] Figure 6 depicts the cyclic voltammetry profile of the Compound 13 recorded in acetonitrile (CH3CN) using SCE as the reference electrode, in accordance with an embodiment of the present disclosure. 15
[0019] Figure 7 depicts the cyclic voltammetry profile of the Compound 15 recorded in acetonitrile (CH3CN) using SCE as the reference electrode, in accordance with an embodiment of the present disclosure. DESCRIPTION OF THE INVENTION
[0020]
Those skilled in the art will be aware that the present disclosure is 20 subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features. 25
Definitions
[0021]
For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the 30 meanings recognized and known to those of skill in the art, however, for
5
convenience and completeness, particular terms and their meanings are set forth below.
[0022]
The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
[0023]
The terms “comprise” and “comprising” are used in the inclusive, open 5 sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”. Throughout this specification, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of elements, or steps but not the exclusion of any other element or step or 10 group of element or steps.
[0024]
The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.
[0025]
In the structural formulae given herein and throughout the present disclosure, the following terms have been indicated meaning, unless specifically 15 stated otherwise.
[0026] The term “molecular film” refers to a film comprising a multimetallic compound as defined herein, which could act as an active constituent in the corresponding device. In an aspect of the present disclosure, the molecular film comprises a compound selected from compounds of Formula I, its salts, 20 stereoisomers, or solvates.
[0027] The term “substrate” refers to the layer or film which acts as a template upon which other components are arranged in order. In an aspect of the present disclosure, the substrate is selected from yttria stabilized zirconia (YSZ), silicon, silicon oxide, silicon nitride, sapphire, or hafnium oxide. 25
[0028] The term "transition metals" as used herein refers to elements from groups 3-12 of the periodic table, including but not limited to Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Db, Sg, and Bh.
[0029] The term "bridging ligand" as used herein refers to a ligand that coordinates 30 to two or more metal centers simultaneously, thereby connecting the metal centers 6
within the multimetallic complex and facilitating electronic communication between them.
[0030] The term "azo" as used herein refers to a functional group characterized by a nitrogen-nitrogen double bond (N=N), which may be incorporated into aromatic or aliphatic systems and exhibits redox-active properties. 5
[0031] The term "redox-active ligand" as used herein refers to a ligand capable of undergoing reversible oxidation and reduction reactions, thereby contributing additional redox states to the overall molecular system beyond those provided by the metal centers alone.
[0032] The term "memory effect" as used herein refers to the ability of a device to 10 retain information about its previous electrical state after the removal of an applied stimulus, achieved through stable changes in electrical properties such as resistance or capacitance.
[0033] The term "switching" as used herein refers to the reversible transition between different electrical states (such as high resistance state and low resistance 15 state) in response to an applied electrical stimulus.
[0034] The term "redox states" as used herein refers to different oxidation states that can be accessed by the metal centers and/or ligands within the multimetallic compound, each corresponding to a distinct electronic configuration and associated electrical properties. 20
[0035] The term "neuromorphic computing" as used herein refers to computing systems that mimic the neural structure and function of biological brains, utilizing devices capable of multiple stable states to represent synaptic weights and enable parallel processing.
[0036] The term "in-memory computing" as used herein refers to computing 25 architectures where data storage and processing occur within the same physical unit, eliminating the need for separate memory and processing components and reducing computational overhead.
[0037] The term "electrically associated" as used herein refers to a configuration where the molecular film is in electrical contact with electrodes such that electrical 30 current can flow through the molecular film between the electrodes. 7
[0038] The term "ionic rearrangement" as used herein refers to the movement and redistribution of counter ions within the molecular film in response to applied electrical fields, which contributes to the stabilization of different molecular states and memory effects.
[0039] The term "capacitive states" as used herein refers to different levels of 5 electrical capacitance exhibited by the molecular film, which can be modulated through changes in molecular conformation, polarization, or ionic distribution.
[0040] The term "vector matrix multiplication (VMM)" as used herein refers to mathematical operations commonly used in artificial intelligence and machine learning algorithms, which can be efficiently performed using analog neuromorphic 10 devices with multiple conductance states.
[0041] The term "root mean square (RMS) roughness" as used herein refers to a measure of surface roughness calculated as the square root of the mean of the squared deviations of surface height from the average surface levelThe term “solvate”, as used herein, refers to a crystal form of a substance which contains 15 solvent. Hydrate is a solvate form of a substance wherein the solvent is water.
[0042] Salts and solvates having counter-ions or associated solvents are within the scope of the present disclosure, for example, for use as intermediates in the preparation of other compounds of Formula I, and their salts. Thus, one embodiment of the disclosure embraces a compound of Formula I, and salts thereof. 20 Compounds according to Formula I contain a basic functional group and are therefore capable of forming acid addition salts by treatment with a suitable salt of the respective anion. Suitable acids include inorganic acids and organic acids. Representative salts include without limitation chloride, tetrafluoroborate, trifluoromethane sulfonate, hexafluorophosphate, and tetraphenylborate. 25
[0043] The term “stereoisomers” refers to two or more isomers of a compound that have the same molecular formula and sequence of bonded atoms but differ in the three-dimensional orientations of their atoms in space. The compounds described herein may contain one or more chiral centres and/or double bonds and therefore, may exist as stereoisomers, such as enantiomers and diastereomers (“E” or “Z” 30 isomer or a mixture of ‘E’ and ‘Z’ isomers). Accordingly, the chemical structures 8
depicted herein encompass all possible enantiomers and stereoisomers of the illustrated or identified compounds including the stereoisomerically pure form (e.g., geometrically pure, enantiomerically pure or diastereomerically pure) and enantiomeric and stereoisomeric mixtures. Further, the mixture of enantiomeric and other stereoisomeric forms can be resolved into their pure component by the 5 methods known in the art, such as chiral-phase gas chromatography, chiral-phase high performance liquid chromatography, crystallization, using chiral derivatizing agents, etc. Also, pure enantiomers and diastereomers can be obtained from intermediates or metabolites and reagents that are in the form of pure enantiomers and diastereoisomers by known asymmetric synthetic methods. 10
[0044] The term “optionally substituted” refers to a molecule substituted or not substituted with functional groups such as halogen, nitro, amino, hydroxy, aryl, alkyl, alkenyl, alkynyl, heteroaryl, heterocyclyl or the like.
[0045] The term “alkyl” refers to a saturated hydrocarbon chain having the specified number of carbon atoms. For example, which are not limited, C1-20 alkyl 15 refers to an alkyl group having from 1 to 20 carbon atoms. Alkyl groups may be straight or branched chained groups which may be optionally substituted. Representative branched alkyl groups have one, two, or three branches. Preferred alkyl groups include, without limitation, methyl, ethyl, n-propyl, and isopropyl, butyl, isobutyl and t-butyl. One or more hydrogens of the alkyl groups may be 20 optionally replaced with deuterium. Similarly, the other atom(s) may be replaced by their respective isotopic forms as well.
[0046] The term “alkenyl” refers to an unsaturated hydrocarbon chain having a specific number of carbon atoms and at least one double bond between carbon atoms. For example, which are not limited, C2-20 alkenyl refers to an alkenyl group 25 having from 2–20 carbon atoms. Alkenyl groups may be straight or branched chain groups which may be optionally substituted. Representative branched alkenyl groups have one, two, or three branches. Preferred alkenyl groups include, without limitation, ethenyl, n-propenyl, and isopropenyl.
[0047] The term “aryl” refers to aromatic systems having 6 to 15 carbon atoms, 30 which may be optionally substituted by one or more substituents. The aryl may be 9
monocyclic, bicyclic or polycyclic and may be fused, bridged or spirocyclic rings. The aryl groups may be optionally substituted. Preferred aryl groups include, but not limited to phenyl, naphthyl and the like.
[0048] The term “heteroaryl” refers to an aryl ring system as defined above having a heteroatom in the ring. The heteroaryl ring system may be attached to the main 5 structure at any heteroatom or carbon atom resulting in the creation of a stable structure. The C1-20 heteroaryl refers to an aromatic ring with one or more hetero atoms selected from N, O or S with carbon ranging between 1 to 20.
[0049] The term “heterocyclyl” refers to a heterocyclic ring system that may be optionally substituted by one or more substituents. The heterocyclyl ring system 10 may be attached to the main structure at any heteroatom or carbon atom resulting in the creation of a stable structure. Furthermore, the term “C1-20 heterocyclyl” refers to a stable 1 to 20 membered ring system, which consists of carbon atoms and heteroatoms selected from nitrogen, phosphorus, oxygen and sulphur. For purposes of this disclosure, the heterocyclic ring system may be monocyclic, 15 bicyclic or tricyclic ring systems, fused, bridged or spirocyclic rings, and the nitrogen, phosphorus, oxygen or sulphur atoms in the heterocyclic ring system, may be optionally oxidized to various oxidation states. The heterocyclic rings further include heteroaryl rings which are aromatic heterocyclic rings. In addition, the nitrogen atom may be optionally quaternized; and the ring system, may be partially 20 or fully saturated. The term “heterocyclyl” refers to monocyclic or polycyclic ring, polycyclic ring system refers to a ring system containing 2 or more rings, preferably bicyclic or tricyclic rings, in which rings can be fused, bridged or spirocyclic rings or any combinations thereof. A fused ring as used herein means that the two rings are linked to each other through two adjacent ring atoms common to both rings. The 25 fused ring can contain 1-4 hetero atoms independently selected from N, O, or S. The rings can be either fused by nitrogen, -CH- or -C- group.
[0050] The term “cycloalkyl” refers to a cyclic carbon moiety comprising saturated bonds between the carbons. The cycloalkyl compounds includes a non-aromatic carbocyclic ring system, polycyclic ring compounds, and bicyclic (spiro, fused, 30 bridged, non-fused) ring compounds. The term C3-20 cycloalkyl comprises 3 to 20
10
carbon atoms. Preferred cycloalkyl groups include, without limitation, cyclopentyl, cycloheptyl, cyclobutyl, or cyclononyl.
[0051] Unless otherwise substituted, the valency of an atom such as carbon, nitrogen, in the compounds of the present disclosure is understood to satisfy by the presence of hydrogen atoms. 5
[0052] The compounds described herein can also be prepared in any solid or liquid physical form, for example the compound can be in a crystalline form, in amorphous form and have any particle size. Furthermore, the compound particles may be micronized or nanonized, or may be agglomerated, particulate granules, powders, oils, oily suspensions, or any other form of solid or liquid physical forms. 10
[0053] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as 15 if each numerical value and sub-range is explicitly recited.
[0054] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the 20 disclosure, the preferred methods, and materials are now described.
[0055]
As discussed in the background, there is a need in the art to develop compounds having multiple redox states and capacitive states. Current memory device technologies face several critical limitations that hinder their suitability for modern computing demands, especially in neuromorphic and in-memory 25 processing systems. Conventional inorganic materials such as TiO2, HfO2, and Ta2O5 typically offer only binary switching, limiting data density and computational flexibility. These systems also require high operating voltages and energy input, making them inefficient for low-power applications. Organic memory devices, while promising, suffer from poor reliability, limited reproducibility, and unclear 30 structure-property relationships. Furthermore, existing molecular designs—
11
particularly monometallic complexes—lack sufficient redox diversity and thermodynamic states, restricting their use in advanced memory architectures. The complexity and cost of current fabrication methods further impede scalability and practical deployment.
[0056]
The present disclosure overcomes these limitations through the 5 development of multimetallic transition metal complexes with redox-active bridging ligands. These compounds enable multiple stable redox states within a single molecular framework, dramatically enhancing switching capabilities and storage density. The bridging ligands, such as azo and heteroaryl groups, contribute additional redox-active sites, allowing for tunable electrical properties and dynamic 10 molecular rearrangements. Devices fabricated using these compounds exhibit fast switching (1 ns to 1×106 ns), low operating voltages (-5 to +5 V), and responsiveness to optical stimuli (200–700 nm). The solution-based fabrication process—such as spin coating or jet printing—simplifies manufacturing and supports large-area scalability. These devices operate in analog, digital, and chaotic 15 modes, enabling efficient vector matrix multiplication and adaptive computing functions. Collectively, the invention provides a robust platform for next-generation memory technologies with superior performance, energy efficiency, and multifunctionality.
[0057]
In summary, conventional organic materials face various challenges in 20 aspects of limited clarity regarding switching mechanisms and lesser redox states. Hence, in order to increase the redox states, and thereby enhance the capacitive states of the materials, the present disclosure provides multimetallic compounds for memristive devices that results in intra-molecular, inter-molecular, or molecule-electrode charge transfer, induced by an electric field. Furthermore, challenges in 25 achieving desired reliability and accuracy also have to be addressed.
[0058]
The above mentioned technical challenges are overcome by the plurality of compounds which form the subject matter for which protection is sought. The compounds of the present disclosure possess structural features such as metal-ligand bonds which are capable of elongation and compression by virtue of which 30 electrical charge capacitance sites get varied. The multimetallic compounds may
12
have labile halide/pseudo halide bridging that may undergo stretching as a function of electric field resulting in change in the polarizations and thus the capacitance of the molecular film comprising these compounds. The compounds of the present disclosure are multimetallic compounds with bridging ligands containing azo- or azo-imine chromophores. These ligands are selected for their low-lying (p*) 5 acceptor orbitals. Employing multi-metallic compounds by combining mono-metallic units using suitable linkers (bridging ligands) facilitates more redox events compared to the corresponding mono-metallic systems.
[0059] The above described memory devices may be used in neuromorphic computing. Neuromorphic computing seeks to mimic the neural structure of the 10 human brain to create energy-efficient and scalable systems capable of complex tasks. Neuromorphic systems often employ memristors as synaptic weights in artificial neural networks due to their ability to store multiple states, thereby enabling the representation of synaptic weights with high precision. Vector matrix multiplication (VMM) is a common operation in many computing algorithms, 15 including those used in AI and machine learning. Dot product engines are analog neuromorphic accelerators that facilitates vector-matrix multiplication with far more energy, space and time efficiency as compared to digital platforms.
[0060]
As would be further explained, in the context of the present subject matter the use of multiple metal centres facilitates multiple redox, electronic, and/or 20 conformational states which in turn enables high resolution at the output of a dot product engine. This in turn facilitates core computing operations in AI/ ML and scientific computing allowing neuromorphic computing operations which are reliable and have high accuracy, without imposing any computational loads. Specifically, the claimed molecules provide memory devices which are capable of 25 operating in many possible thermodynamic (i.e., electronic, geometric, or conformational) states and within energy ranges which do not impact the performant efficiencies of such devices. This, as may be noted, allows memory devices to operate by accessing said states thereby further enabling multiple switching transitions and many possible conductance or capacitive states. 30 13
[0061] The present disclosure further provides a device comprising a molecular film made of transition metal-organic complexes of azo-aromatic based ligands between two electrodes. The film has varying resistivity and permittivity resulting in change in conductance and capacitance of the film. The molecular film of the device can store and compute in analogue/ digital domain or could also be used as 5 chaotic elements. The compounds disclosed herein are ionic where the molecular charge is balanced by counter anions. While electrically controlled redox states offer switching properties, the ionic rearrangement is utilized to stabilize the molecular states which consequently provides memory effect. The number of counter ions being higher in multimetallic compounds than in monometallic 10 compounds, the devices utilising these compounds are offered with various knobs to tune the dynamical properties of the molecular switches.
[0062] Accordingly, there is provided a device having at least two electrodes and a molecular film electrically associated with the electrodes. The molecular film comprises the disclosed multimetallic compounds which is capable of electronic 15 switching through intra-molecular, inter-molecular, molecule-electrode charge transfer.
[0063] Accordingly, the present disclosure provides a compound of Formula I its salts, stereoisomers, or solvates thereof,
(La)mMx(Lb)nM’y(Lc)o 20
Formula I
wherein La, Lb, and Lc are independently selected from azo, N3, halogen, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, or combinations thereof; M at each occurrence, may be identical or different, selected from transition metals; M’ at each 25 occurrence, may be identical or different, selected from transition metals; m is in a range of 1 to 3; n is in a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; or y is in a range of 1 to 6.
[0064]
In another embodiment of the present disclosure, the La, Lb, and Lc are independently selected from azo, N3, halogen, optionally substituted C3-20 30 cycloalkyl, optionally substituted C6-15 aryl, optionally substituted C1-20 14
heterocyclyl, optionally substituted C1-20 heteroaryl, or combinations thereof; M at
each occurrence, may be identical or different, selected from Sc, Ti, V, Cr, Mn, Fe,
Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, Tu, Re, Os, Ir, Pt,
Au, Hg, Tf, Db, Sg, or Bh; M’ at each occurrence, may be identical or different,
5 selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd,
Ag, Cd, Hf, Ta, Tu, Re, Os, Ir, Pt, Au, Hg, Tf, Db, Sg, or Bh; m is in a range of 1 to
3; n is in a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; y is in
a range of 1 to 6.
[0065] In an embodiment of the present disclosure, there is provided a compound
10 as disclosed herein, wherein M and M’ at each occurrence, may be identical or
different and are independently selected from Cr, Mn, Fe, Co, Ni, Os, Pt, Pd, Ru,
Rh, or Ir.
[0066] In an embodiment of the present disclosure, there is provided a compound
as disclosed herein, wherein La, Lb and Lc are independently selected from,
15 , , ,
, , , , , ,
, , , , , ,
15
, , , , azo, N3
, halogen, or combinations
thereof; Y is selected from -C(H)-, -C(C1-10 alkyl)-, or -N-; and Ar, Ar’, Ar”, and
Ar”’ are independently selected from, C1-20 alkyl, C2-20 alkenyl, C6-15 aryl, C3-20
5 cycloalkyl, C1-20 heteroaryl, C1-20 heterocyclyl or stilbene, wherein C1-20 alkyl, C2-
20 alkenyl, C6-15 aryl, C3-20 cycloalkyl, C1-20 heteroaryl, C1-20 heterocyclyl or stilbene
is optionally substituted.
[0067] In an embodiment of the present disclosure, there is provided a compound
10 as disclosed herein, wherein the compound is selected from
Compound 1
Compound 2
16
Compound 3
Compound 4
Compound 5
Compound 6
Compound 7
Compound 8
Compound 9
Compound 10
17
Compound 11
Compound 12
Compound 13
Compound 14
Compound 15 Compound 16
18
Compound 17
Compound 18
Compound 19
Compound 20
19
Compound 21
20
Compound 22
wherein M is selected from Mn, Fe, or Co; X is selected from Cl or Br; and Y is
selected from PF6, BF4, or BPh4.
[0068] In an embodiment of the present disclosure, there is provided a device
comprising: a) at least two electrodes; and b) a molecular film comprising a top
surface and a bottom surface, wherein 5 the molecular film comprises a compound as
disclosed herein, and the molecular film is electrically associated with the at least
two electrodes.
[0069] In an embodiment of the present disclosure, there is provided a device as
disclosed herein, wherein at least two electrodes are independently selected from
10 fluorine doped tin oxide (FTO), indium tin oxide (ITO), chromium, titanium,
platinum, gold, tungsten, nickel, or graphite. In another embodiment if the present
disclosure, at least two electrodes are independently selected from fluorine doped
tin oxide (FTO), indium tin oxide (ITO), gold, or combinations thereof.
[0070] In an embodiment of the present disclosure, there is provided a device as
15 disclosed herein, wherein the molecular film has a thickness in a range of 10 to 100
21
nm; and the at least two electrodes independently have a thickness in a range of 5 to 80 nm.
[0071]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the molecular film has a root mean square roughness in a range of 0.1 to 4 nm. 5
[0072]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the at least two electrodes are selected from a top electrode and a bottom electrode; the molecular film is coated on the bottom electrode.
[0073]
In an embodiment of the present disclosure, there is provided a device as 10 disclosed herein, wherein the device comprises a substrate.
[0074]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the substrate is selected from silicon, silicon oxide, silicon nitride, hafnium oxide, sapphire or yttria stabilized zirconia (YSZ). In another embodiment of the present disclosure, the substrate is yttria stabilized 15 zirconia (YSZ).
[0075]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the device further may comprise metal nanoparticles selected from gold, silver, platinum, tungsten, chromium, titanium or titanium nitride. In another embodiment of the present disclosure, the device further 20 comprises gold nanoparticles.
[0076]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the molecular film, the top electrode and the bottom electrode are arranged in series.
[0077]
In an embodiment of the present disclosure, there is provided a device as 25 disclosed herein, wherein the molecular film exhibits memory effect via ionic and intermolecular rearrangements.
[0078]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the molecular film exhibits at least two redox states.
[0079]
In an embodiment of the present disclosure, there is provided a device as 30 disclosed herein, wherein the molecular film exhibits memory effects arising from
22
ionic and intermolecular rearrangements and from reversible redox transitions of multimetallic complexes.
[0080]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the molecular film comprises multimetallic complexes with associated counteranions, the number and nature of which enable systematic 5 tuning of device properties including conductance, capacitance, switching threshold, and retention.
[0081]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the device is operable in multiple switching regimes, including (i) digital switching characterized by sharp transitions between states, and 10 (ii) analog switching characterized by gradual modulation of conductance or capacitance, the operational regime being selectable by molecular composition and by the pattern and frequency of the applied stimulus.
[0082]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the device demonstrates stable retention of multiple 15 distinct redox-derived states, thereby enabling multi-level data storage and in-memory computing.
[0083]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the device is employable in data storage, in-memory computing, neuromorphic computing, or sensing applications by virtue of its 20 tunable switching dynamics, endurance, and stability.
[0084]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the device exhibits a switching time in a range of 1 ns to 1 × 106 ns. 25
[0085]
In an embodiment of the present disclosure, there is provided a device as disclosed herein, wherein the device exhibits response to a voltage in a range of -5 to 5V; or a light irradiation having wavelength in a range of 200 to 700 nm.
[0086]
In an embodiment of the present disclosure, there is provided a process for preparation of the device as disclosed herein, the process comprising: a. obtaining 30 a solution of a compound as disclosed herein, in the presence of a solvent; b. 23
forming a molecular film of the solution on a bottom electrode; and c. assembling the top electrode upon the top surface of the molecular film to obtain the device.
[0087]
In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the solvent is selected from acetonitrile (CH3CN), dimethyl formamide (DMF), dichloromethane (CH2Cl2), dichloroethane 5 (ClCH2CH2Cl), chloroform (CH3Cl), methanol (CH3OH), ethanol (C2H5OH) or combinations thereof. In another embodiment of the present disclosure, the solvent is selected from CH3CN, dimethyl formamide (DMF), or combinations thereof.
[0088]
In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein forming the film is carried out by spin coating, jet 10 printing, sol-gel coating, slot die coating, or combinations thereof. In another embodiment of the present disclosure, forming the film is carried out by spin coating.
[0089]
In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein forming the film is carried out by spin coating at a speed 15 in a range of 1000 to 12000 rpm, for a period in a range of 20 to 120 seconds.
[0090]
In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein assembling the top electrode is carried out by vacuum vapor deposition method, cluster ion beam method, pulsed laser deposition (PLD) method, chemical vapor deposition (CVD) method, plasma polymerization method, 20 molecular beam epitaxy (MBE) process, or a sputtering method. In another embodiment of the present disclosure, assembling the top electrode is carried out by pulsed laser deposition (PLD) method.
[0091]
In an embodiment of the present disclosure, there is provided a use of the device as disclosed herein, or the compound as disclosed herein, in electronic, 25 electrical, sensory and computing appliance. The above approaches provide a number of technical advantages. For example, in the context of the present subject matter the use of multiple metal centres facilitates multiple redox, electronic, and/or conformational states which in turn enables high resolution at the output of a dot product engine. This in turn facilitates core computing operations in AI/ ML and 30 scientific computing allowing neuromorphic computing operations which are 24
reliable and have high accuracy, without imposing any computational loads. Specifically, the claimed molecules provide memory devices which are capable of operating in many possible thermodynamic (i.e., electronic, geometric, or conformational) states and within energy ranges which do not impact the performant efficiencies of such devices. This, as may be noted, allows memory 5 devices to operate by accessing said states thereby further enabling multiple switching transitions and many possible conductance or capacitive states.
[0092]
In an embodiment of the present disclosure, there is provided a method of using the compound as described herein for use in electronic, electrical, sensory, or computing appliances. In another embodiment of the present disclosure, the 10 computing appliances are selected from the group consisting of neuromorphic computing systems, in-memory computing systems, artificial intelligence processing systems or combinations thereof.
[0093]
In an embodiment of the present disclosure, there is provided a device as described herein for use in electronic, electrical, sensory, or computing appliances. 15 In another embodiment of the present disclosure, the computing appliances are selected from the group consisting of neuromorphic computing systems, in-memory computing systems, artificial intelligence processing systems or combinations thereofAlthough the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations 20 are possible.
EXAMPLES
[0094] The disclosure will now be illustrated with the following examples, which are intended to illustrate the working of disclosure and not intended to take 25 restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and devices, 30 25
the exemplary methods, devices and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply. EXAMPLE 1 5 Preparation of ligands and compounds of the present disclosure
[0095] For the purpose of the present disclosure, the synthesis of selected ligands is provided in below scheme 1. Scheme 1 10
[0096] General procedure for the synthesis of Ligand A and B: The ligands A and B were synthesized following the reported procedure as described follows.
[0097] A solution of 2-nitrosopyridine and either p-phenylenediamine or benzidine-1,4-diaminobiphenyl in dichloromethane (DCM) was treated with a drop 15 of acetic acid and stirred at room temperature for three days. The reaction mixture was then concentrated in vacuo, and residual acetic acid was washed twice with water (10 ml each). The Ligand A or B was purified by thin-layer chromatography (TLC) or column chromatography, using a dichloromethane–acetonitrile mixture as the eluent. 20 Characterization data for Ligand A: 1H NMR (400 MHz, CDCl3) d 8.76 (d, J = 3.2 Hz, 2H), 8.21 (s, 4H), 7.95 (td, J = 7.2, 1.9 Hz, 2H), 7.85 (d, J = 7.8 Hz, 2H), 7.45 (ddd, J = 7.2, 4.2, 1.2 Hz, 2H). ESI-MS (m/z): [M+H]+ 288.85 25
EXAMPLE 2
Synthesis of Compound 2 (Dinuclear Ruthenium Complex with Indigo Bridging Ligand): 26
[0098]
The precursor complex cis-[Ru(pap)2Cl2] (100 mg, 0.19 mmol) (pap=(2-phenylazo)pyridine) and AgClO4 (79 mg, 0.38 mmol) were dissolved in 30 mL of ethanol and refluxed for 2 hours under a dinitrogen atmosphere. The resulting AgCl precipitate was filtered off, and the bridging ligand H2Ind (26 mg, 0.10 mmol) along with NaOH (8 mg, 0.20 mmol) were added to the filtrate. The reaction mixture was 5 then refluxed for 5 hours under dinitrogen atmosphere.
[0099]
After completion of the reaction, the solvent was evaporated under reduced pressure to afford a crude residue. This material was dissolved in a minimal volume of acetonitrile, and 10 mL of saturated NaPF6 solution was added, leading to the formation of a dark precipitate. The solid was collected by filtration, washed twice 10 with ice-cold distilled water, and dried under vacuum.
[00100]
Purification was carried out using neutral alumina thin-layer chromatography. The mononuclear complex was first eluted with a dichloromethane/acetonitrile (5:1) mixture, followed by the dinuclear compound 2 (see Table), which was obtained using a dichloromethane/acetonitrile (1:1) eluent. 15 Removal of solvent under reduced pressure yielded pure [Ru(PAP)2(Ind)Ru(PAP)2][PF6]2 (compound 2).
Characterization Data:
Chemical Formula: C60H44N14O2Ru2
ESI-MS: m/z calculated for [M-2PF6]2+: 598.09; found: 598.08 20
UV-Vis (CH3CN): ?max = 270, 330, 540 nm
Cyclic Voltammetry (CH3CN/TBAPF6, vs. SCE): E1/2 = +1.02, +0.58, -0.29, -0.44, -0.66, -1.12, -1.30, -1.66 V. Voltammogram as shown in Figure 2 reveals multiple redox waves with half-wave potentials (E1/2) observed at +1.01, +0.56, -0.28, -0.42, -0.65, -1.13, -1.32 and -1.67 V, indicating the presence of multiple reversible redox 25 states. These redox events reflect the compound’s ability to undergo successive electron transfer processes, which are critical for enabling multistate switching behavior in molecular memory devices.
Example 3 27
Synthesis of Compound 3 (Dinuclear Ruthenium Complex with Biimidazole
Bridging Ligand)
Following a procedure analogous to that described in Example 2 but using
biimidazole in place of indigo.
5 Characterization Data:
Chemical Formula C50H43N16Ru2P2F12
ESI-MS: m/z calculated for [M-2PF6]2+: 535.069 found: 535.089
Scheme 4
10 EXAMPLE 4
Synthesis of Compound 4
Scheme 2
[00101] A solution of Ru(TD)Cl2(CH3CN) (TD = 2,6-
15 bis(phenylazo)pyridine) was refluxed with 2 equivalents of AgNO3 in ethanol for 4
h. The reaction mixture was cooled to room temperature and filtered through a G4
sintered funnel to remove the precipitated AgCl. To the clear filtrate, 0.5 equivalents
of the bridging ligand were added, and the mixture was refluxed for 24 h. The
28
resulting brown solution was evaporated to dryness, and the residue was dissolved in a minimum volume of acetonitrile. Addition of saturated aqueous NH4PF6 afforded a precipitate, which was thoroughly washed with dichloromethane. The crude product was then crystallized at least thrice using an acetonitrile–toluene mixture (1:1) to yield the pure compound. 5
Chemical Formula: C70H50N16Ru2P4F24
ESI-MS: m/z calculated for [M-4PF6]4+: 329.5631; found: 329.5617
Cyclic Voltammetry (CH3CN/TBAPF6, vs. SCE): E1/2 = -0.035, -0.55, -1.53, -2.07 V.
EXAMPLE 5 10
Synthesis of Compound 8 (Dichloro-Bridged Dinuclear Ruthenium Complex)
Scheme 3
[00102]
Compound 8 was synthesized by first preparing the Ru-arene precursor, (benzene)ruthenium dichloride dimer, [(?6-C6H6)RuCl(µ-Cl)]2, and the 15 neutral tridentate ligand (L), following literature-reported procedures. As illustrated in Scheme 3, a reaction was carried out between [(?6-C6H6)RuCl(µ-Cl)]2 and ligand L in a 1:2 molar ratio in methanol under stirring conditions at room temperature. The reaction mixture immediately turned green, indicating complex formation. Stirring was continued for 1 hour to ensure completion of the reaction. The resulting 20 complex, [(L)RuCl(µ-Cl)]2 (Compound 8), was isolated as a dark green solid after solvent evaporation and subsequent extraction with dichloromethane.
Characterization Data: 1H NMR (400 MHz, CDCl3): d 8.20 (d, 2H), 7.65 (m, 4H), 7.40 (t, 2H), 6.85 (s, 6H, ?6-benzene)
UV-Vis (CH2Cl2): ?max = 315, 425, 565 nm 25 29
Cyclic Voltammetry: E1/2 = +0.65, +1.15, -0.25 V; The cyclic voltammetry data showed multiple redox waves corresponding to different oxidation states accessible to the multimetallic complex.
EXAMPLE 6
Synthesis of Compound 16 5
Scheme 5
[00103]
The precursor complex cis-[Ru(pap)2Cl2] (pap=(2-phenylazo)pyridine) and 2 equiv. of AgClO4 were dissolved in 30 mL of ethanol 10 and refluxed for 2 hours under a dinitrogen atmosphere. The resulting AgCl precipitate was filtered off, and the 0.5 equiv. bridging ligand A was added to the filtrate. The reaction mixture was then refluxed for 48 hours under dinitrogen atmosphere. After completion of the reaction, the solvent was evaporated under reduced pressure to afford a crude residue. This material was dissolved in a minimal 15 volume of acetonitrile, and saturated NH4PF6 solution was added that led to the formation of a dark precipitate, which was washed twice with ice-cold distilled water, and dried under vacuum. The residue was crystallized using an acetonitrile–toluene (1:1) mixture to yield the pure compound.
Chemical Formula: C60H48N18Ru2P4F24 20
ESI-MS: m/z calculated for [M-4PF6]4+: 329.0599; found: 306.0614
EXAMPLE 7
Synthesis of Compound 13 (dichloro-bridged di-cobalt Complex) 30
[00104]
Synthesized following a literature procedure. To an acetonitrile solution of CoL2Cl 1.1 equiv of FcPF6 was added. The mixture was stirred for 2 h, and the color of the solution became brown. It was then evaporated under reduced pressure, and the crude mass was extracted with dichloromethane and crystallized from a dichloromethane–hexane solution. 5
Characterization Data:
Chemical formula: C52H52N12P2F12Co2Cl2
Elementary analysis: Anal. Calcd for C52H52N12P2F12Co2Cl2: C, 47.18; H, 3.96; N, 10 12.70. Found: C, 47.16; H, 3.95; N, 12.68.
Cyclic voltammetry data (CH3CN/NEt4ClO4 vs Ag/AgCl): 0.48, 1.22, -0.81V
EXAMPLE 8
Synthesis of Compound 15 (Mixed Ruthenium/Osmium dinuclear Complex 15 with Biimidazole Bridging Ligand)
[00105]
A mixture of [OsBr2(pap)2] and two equiv. [Ag(H2biim)]NO3 was refluxed in methanol–water (3:1 v/v, 70 mL) for 1 h. During the reaction, the solution color changed from blue to pink. The mixture was cooled to room temperature and filtered through a sintered funnel to remove precipitated AgCl. The 20 pink filtrate was evaporated under reduced pressure to remove methanol, filtered, and concentrated to ~15 mL. To this solution, 2 mL of a saturated aqueous sodium 31
perchlorate solution containing 0.1% perchloric acid was added, yielding a reddish-pink precipitate of [Os(pap)2(H2biim)][ClO4]2, which was collected by filtration and recrystallized from dichloromethane–diethyl ether.
[00106]
The complex [Os(pap)2(H2biim)][ClO4]2 was then dissolved in acetonitrile (30 mL), and 3 equiv. triethylamine was added, producing an intense 5 blue-violet solution. To this, one equiv. [Ru(pap)2(CH3CN)2][ClO4]2 was added, and the mixture was refluxed under nitrogen for 6 h. The solution gradually changed to brown-violet. After cooling, it was concentrated to one-third of its initial volume, and a solid precipitate was obtained upon addition of diethyl ether. The crude product was redissolved in a minimum amount of dichloromethane and purified by 10 column chromatography on neutral alumina (1 × 10 cm). A red-violet band was eluted using dichloromethane–acetonitrile (3:1). The solvent was removed under vacuum. The residue was dissolved in a minimum volume of acetonitrile. Addition of saturated aqueous NH4PF6 afforded a precipitate, which was collected by filtration. The solid was washed three times with dichloromethane, and the 15 remaining residue was recrystallized from dichloromethane–diethyl ether.
Characterization Data:
Chemical formula: C50H43N16OsRuP2F12
Cyclic Voltammetry (CH3CN/NEt4ClO4, vs. SCE): E1/2 = 1.28, 1.10, -0.31, -0.46, -0.84, -0.95, -1.65, -1.87, -2.12 V. 20
[00107]
The development of extended bridging ligands represented a systematic approach to increasing the complexity and functionality of multimetallic systems. These larger bridging units potentially accommodate more metal centers, leading to systems with even greater numbers of accessible redox states. The modular design approach allowed for systematic tuning of electronic properties and 25 switching behavior through controlled variation of bridging ligand structure. EXAMPLE 9
Device Fabrication Using Compound 3
[00108] A stock solution for representative compound 2 from Example 2 was prepared in CH3CN with a concentration between 0.1 and 100 mM. 30 32
[00109] Indium tin oxide (ITO) was grown on annealed yttria-stabilized zirconia (YSZ; substrate) to obtain bottom electrode having a thickness of 5 to 80 nm.
[00110] In an example, the stock solution of compound 3 was filtered through a 0.2 µm syringe filter and subsequently spin-coated onto the surface of the 5 bottom electrode (ITO) at a speed of 3000 rpm, for 2 minutes to obtain a molecular film having root mean square roughness 0.3 to 4 nm and thickness of 10 to 50 nm.
[00111] After deposition, the samples were stored in a vacuum chamber with a pressure of ~10-8 torr for 12 h. Subsequently, a top electrode of ITO was assembled by pulsed laser deposition (PLD) technique upon the molecular film. 10 Thus, stock solutions of the compound 3 was prepared at concentrations ranging from 5 mM to 50 mM. These solutions were used for spin coating to form the active organic layer in the device. The resulting film thickness varied between 5 nm and 50 nm, directly correlating with the concentration of the solution used. Gold nanoparticles were subsequently deposited, with particle diameters ranging from 15 approximately 10 to 200 nm and thicknesses between 10 and 60 nm, contributing to enhanced interfacial properties and device performance. The second conducting layer was deposited with a controlled thickness, consistent with the device architecture, although the exact thickness may vary depending on the deposition method and material used. This process enabled precise control over the active layer 20 morphology and device performance. The substrate (104) is preferably selected from materials that provide mechanical stability and electrical isolation, such as yttria-stabilized zirconia (YSZ), silicon, silicon oxide, hafnium oxide, silicon nitride, or sapphire. In the preferred embodiment, YSZ is utilized due to its excellent thermal stability, chemical inertness, and compatibility with the subsequent 25 processing steps.
[00112] Positioned above the substrate (104) is a bottom electrode (102) which functions as the first electrical contact for the memory device. The bottom electrode (102) is typically formed from conductive materials such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), gold, platinum, chromium, titanium, 30 tungsten, nickel, or graphite. The thickness of the bottom electrode (102) generally 33
ranges from 5 to 80 nanometers, with optimal performance typically achieved at thicknesses between 20 to 60 nanometers. The bottom electrode (102) is deposited using techniques such as pulsed laser deposition (PLD), sputtering, or thermal evaporation to ensure uniform coverage and good adhesion to the substrate (104).
The central active component of the device is the molecular film (103), which 5 comprises the multimetallic transition metal complexes of Formula I as disclosed herein. The molecular film (103) has a bottom surface (103b) that is in direct electrical contact with the bottom electrode (102), and a top surface (103a) that interfaces with the top electrode (101). The molecular film (103) typically has a thickness ranging from 10 to 100 nanometers, with preferred thicknesses between 10 20 to 60 nanometers for optimal switching performance. The root mean square (RMS) roughness of the molecular film (103) is maintained in the range of 0.1 to 4 nanometers to ensure uniform electrical contact and consistent device performance.
The molecular film (103) is formed by solution-based deposition techniques, most commonly spin coating, wherein a solution of the multimetallic complex in an 15 appropriate solvent (such as acetonitrile, dimethyl formamide, or dichloromethane) is applied to the bottom electrode (102) surface. The spin coating process is typically performed at speeds ranging from 1000 to 12000 rpm for periods of 20 to 120 seconds, depending on the desired film thickness and solution concentration.
Completing the device structure is the top electrode (101), which serves as the 20 second electrical contact and is positioned above the top surface (103a) of the molecular film (103). Similar to the bottom electrode (102), the top electrode (101) is composed of conductive materials such as ITO, FTO, gold, platinum, or other suitable metals. The top electrode (101) typically has a thickness in the range of 5 to 80 nanometers and is deposited using vacuum-based techniques such as pulsed 25 laser deposition (PLD), thermal evaporation, sputtering, or chemical vapor deposition (CVD) to avoid damage to the underlying molecular film (103).
[00113] The layered arrangement shown in Figure 1 creates a metal-molecule-metal junction where the molecular film (103) acts as the active switching medium between the two electrodes (101, 102). When electrical bias is applied 30 across the electrodes, the multimetallic complexes within the molecular film (103) 34
undergo redox reactions, conformational changes, and ionic rearrangements that result in reversible changes in the electrical resistance and capacitance of the device. The multiple metal centers and redox-active bridging ligands in the complexes enable access to numerous intermediate resistance states, facilitating multilevel memory operation and neuromorphic computing applications. 5
[00114] The device architecture illustrated in Figure 1 is particularly advantageous because it allows for simple fabrication using solution-processing techniques while maintaining excellent electrical performance. The sandwich structure ensures efficient charge injection from the electrodes into the molecular film, while the controlled film thickness and surface morphology provide consistent 10 switching behavior and high device yield. The substrate (104) provides mechanical support and can accommodate additional circuitry or interconnects as needed for integration into larger electronic systems.
[00115] Optional components that may be incorporated into the device structure include metal nanoparticles (such as gold, silver, or platinum 15 nanoparticles) within or adjacent to the molecular film (103) to enhance switching performance, and additional interfacial layers between the electrodes and molecular film to optimize charge injection characteristics. The modular nature of the device design allows for customization of individual components to meet specific application requirements while maintaining the fundamental switching mechanism 20 provided by the multimetallic molecular complexes.
[00116] The device was further analyzed for their electrical switching and memory properties. The devices fabricated in Example 14 were characterized using a semiconductor parameter analyzer under ambient conditions. Current-voltage (I-V) measurements were performed by applying voltage sweeps from 0 V to +3 V, 25 then to -3 V, and back to 0 V at a sweep rate of 0.1 V/s (Refer Figure 14). The device exhibited clear resistive switching behavior with multiple intermediate resistance states. The initial high resistance state (HRS) of approximately 108 O was switched to a low resistance state (LRS) of approximately 105 O upon application of a positive voltage of +2.5 V. The device could be reset to the HRS by applying a 30 negative voltage of -2.0 V. Importantly, the device demonstrated multilevel
35
switching capabilities with at least four distinct and stable resistance states accessible within the operating voltage range. These intermediate states were stable for extended periods (>104 seconds) and could be reliably accessed through controlled voltage pulses. Pulse switching measurements revealed fast switching times of approximately 50 nanoseconds for transitions between resistance states. 5 The devices maintained their switching characteristics after more than 105 switching cycles, demonstrating excellent endurance properties.
[00117] The electrical characterization data provided direct evidence that the multimetallic complexes functioned effectively as active materials in memory devices. The multilevel switching behavior was identified as a key advantage over 10 conventional binary memory devices, enabling higher information storage density. The low operating voltages and stable switching characteristics made these materials suitable for practical memory applications. The presence of multiple accessible resistance states validated the design principle that multimetallic systems provided enhanced switching capabilities compared to monometallic alternatives. 15
[00118] The above examples conclusively demonstrate the successful development of a novel class of multimetallic transition metal complexes tailored for memory device applications. Similar to Compound 3, the remaining compounds disclosed in the present disclosure are expected to exhibit comparable performance characteristics, owing to their shared structural features and redox-active properties. 20 Their behavior under device-relevant conditions is anticipated to align with the observed results for Compound 3, supporting their suitability for memory device applications.
[00119] Through a systematic approach encompassing synthesis, characterization, and device fabrication, the resulting materials exhibited superior 25 switching properties compared to conventional technologies. The multimetallic architecture enabled access to multiple stable redox states within a single molecular framework, forming the basis for multilevel memory devices with enhanced data storage density and computational performance.
ADVANTAGES OF THE PRESENT DISCLOSURE 30 36
[00120] The present disclosure introduces compounds that are used in the fabrication of novel class of memory devices. The compounds (multimetallic transition metal complexes with redox-active bridging ligands), offered substantial improvements over conventional memory technologies. The multimetallic architecture enables multiple redox states within a single molecular system, 5 significantly increasing the number of accessible switching states and supporting high-density data storage and advanced computational functions, particularly in neuromorphic applications. Redox-active bridging ligands, such as azo-containing compounds, add further switching mechanisms, enhancing electrical versatility. Devices fabricated using these compounds demonstrate fast switching (1 ns to 10 1×106 ns), low operating voltages (-5 to +5 V), and excellent reproducibility. The solution-processable fabrication method allows for low-cost, large-area manufacturing without high-temperature or vacuum-based steps. These devices are stable under ambient conditions and compatible with various substrates and electrode materials. Their multifunctional responsiveness to electrical and optical 15 stimuli, combined with analog, digital, and chaotic operational modes, makes them ideal for next-generation memory, sensing, and adaptive computing systems. In certain embodiments, extended bridging ligands are employed as a systematic design strategy to increase the complexity and functionality of multimetallic systems. Such extended bridging units are capable of accommodating a greater 20 number of metal centers, thereby enabling access to an increased number of stable thermodynamic redox states, in some instances up to eight distinct molecular redox states. Transitions among these redox states provide a spectrum of non-volatile analog states exhibiting different kinetic profiles, thereby enabling multi-level data storage and processing. The multimetallic complexes further incorporate up to six 25 counteranions, which contribute to the modulation of device behavior by influencing polarization, capacitive response, conductive characteristics, non-volatility, and switching dynamics. Through such counteranion control, device functional tunability, plasticity, and applicability in in-memory computing and neuromorphic elements are significantly enhanced. The modular design approach 30 37
further permits systematic tuning of electronic properties and switching characteristics through controlled variation of the bridging ligand structure. 38
I/We Claim:
1. A compound of Formula I its salts, stereoisomers, or solvates thereof,
(La)mMx(Lb)nM’y(Lc)o
Formula I
wherein La, Lb, and Lc are independently selected from azo, N3, halogen, 5 optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, or combinations thereof; M at each occurrence, may be identical or different, selected from transition metals; M’ at each occurrence, may be identical or different, selected from transition metals; m is in a range of 1 to 3; n is in 10 a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; or y is in a range of 1 to 6.
2.
The compound as claimed in claim 1, wherein the La, Lb, and Lc are independently selected from azo, N3, halogen, optionally substituted C3-20 cycloalkyl, optionally substituted C6-15 aryl, optionally substituted C1-20 15 heterocyclyl, optionally substituted C1-20 heteroaryl, or combinations thereof; M at each occurrence, may be identical or different, selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, Tu, Re, Os, Ir, Pt, Au, Hg, Tf, Db, Sg, or Bh; M’ at each occurrence, may be identical or different, selected from Sc, Ti, V, Cr, Mn, 20 Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, Tu, Re, Os, Ir, Pt, Au, Hg, Tf, Db, Sg, or Bh; m is in a range of 1 to 3; n is in a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; y is in a range of 1 to 6.
3.
The compound as claimed in claim 1, wherein M and M’ at each occurrence, 25 may be identical or different and are independently selected from Cr, Mn, Fe, Co, Ni, Os, Pt, Pd, Ru, Rh, or Ir. 39
4. The compound as claimed in claim 1, wherein La, Lb and Lc are
independently selected from, , ,
, , , ,
, , , ,
5 , , , , , ,
, , ,
azo, N3, halogen, or
combinations thereof; Y is selected from -C(H)-, -C(C1-10 alkyl)-, or -N-;
40
and Ar, Ar’, Ar”, and Ar”’ are independently selected from, C1-20 alkyl, C2-
20 alkenyl, C6-15 aryl, C3-20 cycloalkyl, C1-20 heteroaryl, C1-20 heterocyclyl or
stilbene, wherein C1-20 alkyl, C2-20 alkenyl, C6-15 aryl, C3-20 cycloalkyl, C1-20
heteroaryl, C1-20 heterocyclyl or stilbene is optionally substituted.
5 5. The compound as claimed in claim 1, wherein the compound is selected
from
Compound 1
Compound 2
Compound 3
Compound 4
Compound 5
Compound 6
41
Compound 7
Compound 8
Compound 9
Compound 10
Compound 11
Compound 12
Compound 13
Compound 14
42
Compound 15 Compound 16
Compound 17
Compound 18
Compound 19
Compound 20
43
Compound 21
Compound 22
44
; wherein M is selected from Mn, Fe, or Co; X is selected from Cl or Br; and Y is selected from PF6, BF4, or BPh4.
6.
A device comprising: a) at least two electrodes; and b) a molecular film comprising a top surface and a bottom surface, wherein the molecular film comprises a compound as claimed in any one of the claims 1-5, and the 5 molecular film is electrically associated with the at least two electrodes.
7.
The device as claimed in claim 6, wherein at least two electrodes are independently selected from fluorine doped tin oxide (FTO), indium tin oxide (ITO), chromium, titanium, platinum, gold, tungsten, nickel, or graphite. 10
8.
The device as claimed in claim 6, wherein the molecular film has a thickness in a range of 10 to 100 nm; and the at least two electrodes independently have a thickness in a range of 5 to 80 nm.
9.
The device as claimed in claim 6, wherein the molecular film has a root mean square roughness in a range of 0.1 to 4 nm. 15
10.
The device as claimed in claim 6, wherein the at least two electrodes are selected from a top electrode and a bottom electrode; the molecular film is coated on the bottom electrode.
11.
The device as claimed in claim 6, wherein the device comprises a substrate.
12.
The device as claimed in claim 6, wherein the substrate is selected from 20 silicon, silicon oxide, silicon nitride, sapphire, hafnium oxide or yttria stabilized zirconia (YSZ).
13.
The device as claimed in claim 6, wherein the device further may comprise metal nanoparticles selected from gold, silver, platinum, tungsten, chromium, titanium, or titanium nitride. 25
14.
The device as claimed in claim 6, wherein the molecular film, the top electrode, and the bottom electrode are arranged in series.
15.
The device as claimed in claim 6, wherein the molecular film exhibits memory effects arising from ionic and intermolecular rearrangements and from reversible redox transitions of multimetallic complexes. 30 45
16.
The device as claimed in claim 6, wherein the molecular film comprises multimetallic complexes with associated counteranions, the number and nature of which enable systematic tuning of device properties including conductance, capacitance, switching threshold, and retention.
17.
The device as claimed in claim 6, wherein the device is operable in 5 multiple switching regimes, including (i) digital switching characterized by sharp transitions between states, and (ii) analog switching characterized by gradual modulation of conductance or capacitance, the operational regime being selectable by molecular composition and by the pattern and frequency of the applied stimulus. 10
18.
The device as claimed in claim 6, wherein the device demonstrates stable retention of multiple distinct redox-derived states, thereby enabling multi-level data storage and in-memory computing.
19.
The device as claimed in claim 6, wherein the device is employable in data storage, in-memory computing, neuromorphic computing, or sensing 15 applications by virtue of its tunable switching dynamics, endurance, and stability.
20.
The device as claimed in claim 6, wherein the device exhibits a switching time in a range of 1 ns to 1 × 106 ns.
21.
The device as claimed in claim 6, wherein the device exhibits response to 20 a voltage in a range of -5 to 5V; or a light irradiation having wavelength in a range of 200 to 700 nm.
22.
A process for preparation of the device as claimed in any one of the claims 6-21, the process comprising: a. obtaining a solution of a compound as disclosed herein, in the presence of a solvent; b. forming a molecular film 25 of the solution on a bottom electrode; and c. assembling the top electrode upon the top surface of the molecular film to obtain the device.
23.
The process as claimed in claim 22, wherein the solvent is selected from acetonitrile (CH3CN), dimethyl formamide (DMF), dichloromethane (CH2Cl2), dichloroethane (ClCH2CH2Cl), chloroform (CH3Cl), methanol 30 (CH3OH), ethanol (C2H5OH) or combinations thereof. 46
24.
The process claimed in claim 22, wherein forming the film is carried out by spin coating, jet printing, sol-gel coating, slot die coating, or combinations thereof.
25.
The process as claimed in claim 22, wherein forming the film is carried out by spin coating at a speed in a range of 1000 to 12000 rpm, for a period 5 in a range of 20 to 120 seconds.
26.
The process as claimed in claim 22, wherein assembling the top electrode is carried out by vacuum vapor deposition method, cluster ion beam method, pulsed laser deposition (PLD) method, chemical vapor deposition (CVD) method, plasma polymerization method, molecular beam epitaxy 10 (MBE) process, or a sputtering method.
27.
Use of the device as claimed in any one of the claims 6-21, or the compound as claimed in claim 1-5, in electronic, electrical, sensory and computing appliance.
28.
A method of using the compound as claimed in any one of claims 1-5 or 15 the device as claimed in claim 6 in electronic, electrical, sensory, or computing appliances.
29.
The method as claimed in claim 28, wherein the computing appliances is selected from the group consisting of neuromorphic computing systems, in-memory computing systems, artificial intelligence processing systems 20 or combinations thereof.
47
ABSTRACT
MULTIMETALLIC COMPOUNDS AND IMPLEMENTATIONS THEREOF The present invention relates to compound of Formula I its salts, stereoisomers, or 5 solvates thereof,
(La)mMx(Lb)nM’y(Lc)o
Formula I
These compounds exhibit multiple stable redox states and tunable electrical properties, making them suitable for advanced memory and computing 10 applications. The present disclosure further provides a device comprising at least two electrodes and a molecular film formed from these compounds, electrically associated with the electrodes. A simplified fabrication process is also disclosed. The compounds and devices are applicable in electronic, electrical, sensory, and computing appliances, offering enhanced switching capabilities, low power 15 operation, and multifunctional responsiveness for next-generation neuromorphic and in-memory computing platforms. 48 ,CLAIMS:I/We Claim:
1. A compound of Formula I its salts, stereoisomers, or solvates thereof,
(La)mMx(Lb)nM’y(Lc)o
Formula I
wherein La, Lb, and Lc are independently selected from azo, N3, halogen, 5 optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, or combinations thereof; M at each occurrence, may be identical or different, selected from transition metals; M’ at each occurrence, may be identical or different, selected from transition metals; m is in a range of 1 to 3; n is in 10 a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; or y is in a range of 1 to 6.
2.
The compound as claimed in claim 1, wherein the La, Lb, and Lc are independently selected from azo, N3, halogen, optionally substituted C3-20 cycloalkyl, optionally substituted C6-15 aryl, optionally substituted C1-20 15 heterocyclyl, optionally substituted C1-20 heteroaryl, or combinations thereof; M at each occurrence, may be identical or different, selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, Tu, Re, Os, Ir, Pt, Au, Hg, Tf, Db, Sg, or Bh; M’ at each occurrence, may be identical or different, selected from Sc, Ti, V, Cr, Mn, 20 Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, Tu, Re, Os, Ir, Pt, Au, Hg, Tf, Db, Sg, or Bh; m is in a range of 1 to 3; n is in a range of 1 to 3; o is in a range of 1 to 3; x is in a range of 1 to 6; y is in a range of 1 to 6.
3.
The compound as claimed in claim 1, wherein M and M’ at each occurrence, 25 may be identical or different and are independently selected from Cr, Mn, Fe, Co, Ni, Os, Pt, Pd, Ru, Rh, or Ir. 39
4. The compound as claimed in claim 1, wherein La, Lb and Lc are
independently selected from, , ,
, , , ,
, , , ,
5 , , , , , ,
, , ,
azo, N3, halogen, or
combinations thereof; Y is selected from -C(H)-, -C(C1-10 alkyl)-, or -N-;
40
and Ar, Ar’, Ar”, and Ar”’ are independently selected from, C1-20 alkyl, C2-
20 alkenyl, C6-15 aryl, C3-20 cycloalkyl, C1-20 heteroaryl, C1-20 heterocyclyl or
stilbene, wherein C1-20 alkyl, C2-20 alkenyl, C6-15 aryl, C3-20 cycloalkyl, C1-20
heteroaryl, C1-20 heterocyclyl or stilbene is optionally substituted.
5 5. The compound as claimed in claim 1, wherein the compound is selected
from
Compound 1
Compound 2
Compound 3
Compound 4
Compound 5
Compound 6
41
Compound 7
Compound 8
Compound 9
Compound 10
Compound 11
Compound 12
Compound 13
Compound 14
42
Compound 15 Compound 16
Compound 17
Compound 18
Compound 19
Compound 20
43
Compound 21
Compound 22
44
; wherein M is selected from Mn, Fe, or Co; X is selected from Cl or Br; and Y is selected from PF6, BF4, or BPh4.
6.
A device comprising: a) at least two electrodes; and b) a molecular film comprising a top surface and a bottom surface, wherein the molecular film comprises a compound as claimed in any one of the claims 1-5, and the 5 molecular film is electrically associated with the at least two electrodes.
7.
The device as claimed in claim 6, wherein at least two electrodes are independently selected from fluorine doped tin oxide (FTO), indium tin oxide (ITO), chromium, titanium, platinum, gold, tungsten, nickel, or graphite. 10
8.
The device as claimed in claim 6, wherein the molecular film has a thickness in a range of 10 to 100 nm; and the at least two electrodes independently have a thickness in a range of 5 to 80 nm.
9.
The device as claimed in claim 6, wherein the molecular film has a root mean square roughness in a range of 0.1 to 4 nm. 15
10.
The device as claimed in claim 6, wherein the at least two electrodes are selected from a top electrode and a bottom electrode; the molecular film is coated on the bottom electrode.
11.
The device as claimed in claim 6, wherein the device comprises a substrate.
12.
The device as claimed in claim 6, wherein the substrate is selected from 20 silicon, silicon oxide, silicon nitride, sapphire, hafnium oxide or yttria stabilized zirconia (YSZ).
13.
The device as claimed in claim 6, wherein the device further may comprise metal nanoparticles selected from gold, silver, platinum, tungsten, chromium, titanium, or titanium nitride. 25
14.
The device as claimed in claim 6, wherein the molecular film, the top electrode, and the bottom electrode are arranged in series.
15.
The device as claimed in claim 6, wherein the molecular film exhibits memory effects arising from ionic and intermolecular rearrangements and from reversible redox transitions of multimetallic complexes. 30 45
16.
The device as claimed in claim 6, wherein the molecular film comprises multimetallic complexes with associated counteranions, the number and nature of which enable systematic tuning of device properties including conductance, capacitance, switching threshold, and retention.
17.
The device as claimed in claim 6, wherein the device is operable in 5 multiple switching regimes, including (i) digital switching characterized by sharp transitions between states, and (ii) analog switching characterized by gradual modulation of conductance or capacitance, the operational regime being selectable by molecular composition and by the pattern and frequency of the applied stimulus. 10
18.
The device as claimed in claim 6, wherein the device demonstrates stable retention of multiple distinct redox-derived states, thereby enabling multi-level data storage and in-memory computing.
19.
The device as claimed in claim 6, wherein the device is employable in data storage, in-memory computing, neuromorphic computing, or sensing 15 applications by virtue of its tunable switching dynamics, endurance, and stability.
20.
The device as claimed in claim 6, wherein the device exhibits a switching time in a range of 1 ns to 1 × 106 ns.
21.
The device as claimed in claim 6, wherein the device exhibits response to 20 a voltage in a range of -5 to 5V; or a light irradiation having wavelength in a range of 200 to 700 nm.
22.
A process for preparation of the device as claimed in any one of the claims 6-21, the process comprising: a. obtaining a solution of a compound as disclosed herein, in the presence of a solvent; b. forming a molecular film 25 of the solution on a bottom electrode; and c. assembling the top electrode upon the top surface of the molecular film to obtain the device.
23.
The process as claimed in claim 22, wherein the solvent is selected from acetonitrile (CH3CN), dimethyl formamide (DMF), dichloromethane (CH2Cl2), dichloroethane (ClCH2CH2Cl), chloroform (CH3Cl), methanol 30 (CH3OH), ethanol (C2H5OH) or combinations thereof. 46
24.
The process claimed in claim 22, wherein forming the film is carried out by spin coating, jet printing, sol-gel coating, slot die coating, or combinations thereof.
25.
The process as claimed in claim 22, wherein forming the film is carried out by spin coating at a speed in a range of 1000 to 12000 rpm, for a period 5 in a range of 20 to 120 seconds.
26.
The process as claimed in claim 22, wherein assembling the top electrode is carried out by vacuum vapor deposition method, cluster ion beam method, pulsed laser deposition (PLD) method, chemical vapor deposition (CVD) method, plasma polymerization method, molecular beam epitaxy 10 (MBE) process, or a sputtering method.
27.
Use of the device as claimed in any one of the claims 6-21, or the compound as claimed in claim 1-5, in electronic, electrical, sensory and computing appliance.
28.
A method of using the compound as claimed in any one of claims 1-5 or 15 the device as claimed in claim 6 in electronic, electrical, sensory, or computing appliances.
29.
The method as claimed in claim 28, wherein the computing appliances is selected from the group consisting of neuromorphic computing systems, in-memory computing systems, artificial intelligence processing systems 20 or combinations thereof.