TECHNICAL FIELD
The present disclosure is in the field of chemical sciences. It generally relates to a self-assembled coordination polymer of formula I and a process for preparing said self-assembled coordination polymers. Further, the present disclosure provides a method of detecting quenchers such as high energy material(s), a metal containing salt(s), an electron deficient analyte(s) and combinations thereof. Furthermore, the present disclosure provides a sensor or sensor array for detection of high energy material(s) or a metal-containing salt(s) or an electron-deficient analyte(s) comprising a self-assembled coordination polymer.
BACKGROUND OF THE DISCLOSURE
Chemical weapons and explosives present immediate threats to public health and safety. For civilian safety reasons, together with the protection of the environment, detection of high energy materials (explosives and related systems) continues to be a highly pressing and challenging task for fundamental researchers and technologists. Over the years, a number of detection methods have been developed which include not only the electrochemical approach but also the usage of analytical equipment such as energy dispersive X-ray diffraction (EDXRD), plasma desorption mass spectrometry (PDMS), surface-enhanced Raman spectroscopy (SERS), and ion mobility spectrometry (IMS). Although these instrument-based methods offer advantages, they are notably expensive and necessitate frequent calibrations by skilled hands. Besides, their larger size especially poses difficulty in deploying at the field. Moreover, they are susceptible to yield false data or false-negative readings due to contaminants or interference of certain compounds.
To overcome the issues associated with instrument-based methods, fluorescence detection methods were explored of which, coordination polymer (COP)-based Fluorescent detection methods have proven to be highly promising due to its simplicity, selectivity, high sensitivity, reversibility, ease of operability and economic feasibility. Moreover, coordination polymers (COPs) can be regarded as

true multifunctional materials by virtue of their ability to generate pores of varying size and shape, high surface area, and tailorable functional sites. However, in order to achieve ultra-selectivity, high-sensitivity, wider linear ranges, and quick response time, there is a huge scope for the design and synthesis of new fluorescent COPs. In recent years, it is observed that COPs capable of forming an infinite 2D layer, serve as highly selective and sensitive fluorescence chemosensor for HEMs. However, COPs to be used in explosive detective devices obviously need to be highly resistant to heat, moisture and air, inexpensive, and industrially scalable. Thus, there is an existent challenge to design and attain industrially scalable multifunctional COPs.
Therefore, the present application provides COPs which are prepared in a simple, hassle-free, multi-gram scale including its rapid synthesis at ambient temperature and capable of forming an infinite 2D layer resulting from the self-assembly of one-dimensionally extended neutral metal-complexes through H-bonding and its use in detecting high energy materials (HEMs).
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure where:
Figure 1 shows IR spectra of the COPs (a) Zn(BTA), (b) Cd(BTA), (c) Gd(BTA) & (d) Pr(BTA). The peak corresponding to NH stretching around 3200 cm-1 becomes broader upon complexation and depicting the loss of its double form which is found in free amine.

Figure 2 shows Raman spectra of the COPs (a) Zn(BTA), (b) Cd(BTA), (c) Gd(BTA) & (d) Pr(BTA). The presence of G and D bands corresponds to the possible 2D structure in the system
Figure 3 shows UV-Vis spectra of the COPs dispersed in DMF (a) Zn(BTA), (b) Cd(BTA), (c) Gd(BTA) & (d) Pr(BTA).
Figure 4 shows XRD plots of the COPs (a) Zn(BTA), (b) Cd(BTA), (c) Gd(BTA) & (d) Pr(BTA).
Figure 5 shows plots a-d corresponding to the XPS studies on the COP, Zn(BTA); (a) Wide scan (survey scan) showing the presence of different elements present, (b) C 1s region, (c) N 1s region and (d) Zn 3d region.
Figure 6 shows plots a-d corresponding to the XPS studies on the COP, Cd(BTA). (a) Wide scan (survey scan) showing the presence of different elements present, (b) C 1s region, (c) N 1s region and (d) Cd 3d region.
Figure 7 shows plots a-d corresponding to the XPS studies on the COP, Gd(BTA). (a) Wide scan (survey scan) showing the presence of different elements present, (b) C 1s region, (c) N 1s region and (d) Gd 3d region.
Figure 8 shows plots a-d corresponding to the XPS studies on the COP, Pr(BTA). (a) Wide scan (survey scan) showing the presence of different elements present, (b) C 1s region, (c) N 1s region and (d) Pr 3d region
Figure 9 shows the FESEM images of the COPs prepared. (a) & (b) Zn(BTA), (c) & (d) Cd(BTA), (e) & (f) Gd(BTA) and (g) & (h) Pr(BTA). It clearly shows the formation of a sheet-like (layer like) arrangement, which was predicted.
Figure 10 shows HRTEM images of the COPs prepared. (a) & (b) Zn(BTA), (c) & (d) Cd(BTA), (e) & (f) Gd(BTA) and (g) & (h) Pr(BTA).
Figure 11 shows EDAX plots indicating the elements present (A) Zn(BTA), (B) Cd(BTA), (c) Gd(BTA) & (D) Pr(BTA). The inset (a) in all the plots show the

elemental composition in each of the COP and inset (b) shows the highlighted image where the EDAX was recorded.
Figure 12 shows profiles depicting the fluorescence spectra of the COPs in solution state dispersed in DMF. (a) Zn(BTA), (b) Cd(BTA), (c) Gd(BTA) & (d) Pr(BTA).
Figure 13 shows UV-Vis, PL spectra and Plot of PL intensity V/S Absorbance respectively for calculating gradient of the (a), (b) & (c) Fluorescene sodium, (d), (e) & (f) Zn(BTA), (g), (h) & (i) Cd(BTA), (j), (k) & (l) Gd(BTA) and (m), (n) & (o) Pr(BTA).
Figure 14 shows Fluorescence spectra of Zn(BTA) in DMF upon gradual addition of micromolar (a) TNP, (b) PNT, (c) TNT, (d) RDX, (e) CL-20 and (f) PETN solution in acetone; (g)-(i) Respective Stern-Volmer plot depicting the quenching mechanism.
Figure 15 shows Fluorescence spectra of Cd(BTA) in DMF upon gradual addition of micromolar (a) TNP, (b) PNT, (c) TNT, (d) RDX, (e) CL-20 and (f) PETN solution in acetone; (g)-(l) Respective Stern-Volmer plot depicting the quenching mechanism.
Figure 16 shows Fluorescence spectra of Gd(BTA) in DMF upon gradual addition of micromolar (a) TNP, (b) PNT, (c) TNT, (d) RDX, (e) CL-20 and (f) PETN solution in acetone; (g)-(l) Respective Stern-Volmer plot depicting the quenching mechanism.
Figure 17 shows Fluorescence spectra of Pr(BTA) in DMF upon gradual addition of micromolar (a) TNP, (b) PNT, (c) TNT, (d) RDX, (e) CL-20 and (f) PETN solution in acetone; (g)-(l) Respective Stern-Volmer plot depicting the quenching mechanism.
Figure 18 shows the comparative account of the efficiency of various quenchers in different COP fluorophore.

Figure 19 shows plot depicting the quenching sensitivity towards HEMs TNP and TNT respectively in (a) & (b) Zn(BTA), (c) & (d) Cd(BTA), (e) & (f) Gd(BTA) and (g) & (h) Pr(BTA).
Figure 20 shows absorption spectra of fluorophore upon addition of quencher TNP (0-40 μM) in acetone and corresponding Benesi-Hilderbrand plot (a) & (b) Zn(BTA), (c) & (d) Cd(BTA), (e) & (f) Gd(BTA).
Figure 21 shows HOMO and LUMO energy values and orbital diagrams of the explosive quenchers used.
Figure 22 shows selective fluorescence quenching observed in the presence of different metal salts in aqueous condition with Cd(BTA) as a fluorophore. (a) Fluorescence spectra depicting quenching upon addition of aqueous metal salt solutions & (b) comparison of quenching efficiencies in the presence of different metal salts.
Figure 23 shows plots depicting the fluorescence quenching in case of (a) Zn(BTA), (b) Cd(BTA) & Pr(BTA) upon addition of known concentration of aqueous mercuric acetate solution.
Figure 24: Stern-Volmer plots of the (a) Zn(BTA), (b) Cd(BTA) & Pr(BTA) with mercuric salt as the quencher
DESCRIPTION OF THE DISCLOSURE
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the description of the disclosure. It should also be realized by those skilled in the art that such equivalent methods do not depart from the scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to the co-ordination polymers, method of its preparation and use, together with further objects and advantages will be better understood from the following description when considered in connection with the

accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. Further, for the purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and sequences, except where expressly specified to the contrary.
Thus, before describing the present invention in detail, it is to be understood that this invention is not limited to particularly exemplified process parameters or methods that may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to limit the scope of the invention in any manner.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example, in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure. Thus, the use of examples anywhere in this specification, including examples of any terms discussed herein is illustrative only, and in no way limits the scope and meaning of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification.
Unless otherwise defined, 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 invention pertains. In case of conflict, the present document, including definitions, will control.
It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the content clearly

dictates otherwise. Thus, for example, a reference to a "solvent" may include two or more such solvents.
The terms "preferred" and "preferably" refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.
As used herein, the terms "comprising" "including," "having," "containing," "involving," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Further, the terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a method that comprises a list of acts does not include only those acts but may include other acts not expressly listed or inherent to such method. In other words, one or more acts in a method proceeded by “comprises… a” does not, without more constraints, preclude the existence of other acts or additional acts.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. Various singular/plural permutations may be expressly set forth herein for the sake of clarity.
Any discussion of documents, methods, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

A detailed description for the purpose of illustrating representative embodiments of the present invention is given below, but these embodiments should not be construed as limiting the present invention.


The present disclosure relates to a self-assembled coordination polymer of formula I
In an embodiment of the present disclosure, the metal is selected from a group comprising Zinc, Cadmium, Gadolinium and Praseodymium.
In another embodiment of the present disclosure, the aryl moiety of the self-assembled coordination polymer is


The present disclosure also provides a process for preparing the self-assembled coordination polymer of formula I, wherein the process comprising reacting metal salt with aryltetramine or salts of aryltetramine in the presence of an aqueous alkali.
In an embodiment of the present disclosure, the metal salt is selected from a group comprising Zinc acetate, Cadmium acetate, Gadolinium acetate and Praseodymium acetate.
In another embodiment of the present disclosure, the aryltetramine is 1,2,4,5-benzenetetramine.
In yet another embodiment of the present disclosure, the salts of aryltetramine is 1,2,4,5-benzenetetramine tetrahydrochloride.
In still another embodiment of the present disclosure, the aqueous alkali is aqueous ammonia.
In still another embodiment of the present disclosure, the process is carried out at a temperature ranging from about 25 °C to about 30 °C, and for a time period ranging from about 1 hour to about 4 hours.
In still another embodiment of the present disclosure, the process is carried out at a temperature ranging from about 25 °C to about 30 °C, and for a time period ranging from about 1 hour to about 4 hours under rapid stirring conditions.

In still another embodiment of the present disclosure, the reaction is carried out at a temperature of about 25 °C, about 26°C, about 27 °C, about 28 °C, about 29 °C or about 30°C.
In still another embodiment of the present disclosure, the reaction is carried out for a time period ranging from about 1 hour, about 2 hours, about 3 hours or about 4 hours.
In still another embodiment of the present disclosure, the reaction is carried out for a time period ranging from about 90 minutes, about 150 minutes, about 210 minutes.
In an embodiment of the present disclosure, the reactants are selected in the above process such that at least one of the reactants aryltetramine or salts of aryltetramine and metal salt intrinsically support fluorescence.
The present disclosure also provides a process for preparing the self-assembled coordination polymer of the compound of formula I as describes above, wherein the process comprising step of reacting metal salt with 1,2,4,5-benzenetetramine tetrahydrochloride in the presence of aqueous ammonia.


In an exemplary embodiment, the present disclosure provides a process for preparing self-assembled coordination polymer Zn(BTA), wherein the process comprising a step of reacting zinc acetate with 1,2,4,5-benzenetetramine tetrahydrochloride in the presence of aqueous ammonia.
In another exemplary embodiment, the present disclosure provides a process for preparing self-assembled coordination polymer of compound Cd(BTA)comprises a step of reacting cadmium acetate with 1,2,4,5-benzenetetramine tetrahydrochloride in the presence of aqueous ammonia.
In yet another exemplary embodiment, the present disclosure provides a process for preparing self-assembled coordination polymer of compound Gd(BTA), wherein the process comprising a step of reacting Gadolinium acetate with 1,2,4,5-benzenetetramine tetrahydrochloride in presence of aqueous ammonia. In still another exemplary embodiment, the present disclosure provides a process for preparing self-assembled coordination polymer of compound Pr(BTA), wherein the process comprising a step of reacting Praseodymium acetate with 1,2,4,5-benzenetetramine tetrahydrochloride in the presence of aqueous ammonia.
In yet another embodiment of the present disclosure, the process further comprises isolation and/or purification of the corresponding product; wherein said isolation is carried out by acts selected from a group comprising the addition of solvent, the addition of ionic resin, quenching, filtration, extraction and combination of acts thereof; and wherein the purification is carried out using ion-exchange resin.
The present disclosure also provides a method of detecting a quencher, the method comprising:
a. dispersing a solution of the self-assembled coordination polymer followed by sonication,

b. dissolving the quencher in an organic solvent to obtain a quenching
solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer; and
d. measuring the change of fluorescence of the self-assembled coordination
polymer.
In an embodiment of the present disclosure, the quencher is selected from a group comprising a high energy material, a metal-containing salt, an electron-deficient analyte and combinations thereof.
In another embodiment of the present disclosure, the high energy material comprises one or more nitro (-NO2) groups.
In yet another embodiment of the present disclosure, the high energy material is selected from a group comprising picric acid (trinitro phenol, TNP), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), 2,3-dimethyl-2,3-dinitrobutane (DMNB), hexanitrohexaazaisowurtzitane (CL20), pentaerythritol tetranitrate (PETN) and cyclotrimethylene-trinitramine (RDX).
In still another embodiment of the present disclosure, the metal-containing salt is selected from a group comprising mercury salt, silver salt, cupric salt, cuprous salt, sodium salt, ammonium salt, nickel salt, zinc salt and combinations thereof.
In still another embodiment of the present disclosure, the electron-deficient analyte is p-nitrophenol.
In an exemplary embodiment of the present disclosure, the method of detecting a quencher comprising:
a. dispersing a solution of self-assembled coordination polymer Zn(BTA)
followed by sonication,

b. dissolving the quencher in an organic solvent to obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Zn(BTA); and
d. measuring the change of fluorescence of the self-assembled coordination
polymer Zn(BTA).
In another exemplary embodiment of the present disclosure, the method of detecting a quencher comprising:
a. dispersing a solution of self-assembled coordination polymer Cd(BTA)
followed by sonication,
b. dissolving the quencher in an organic solvent to obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Cd(BTA); and
d. measuring the change of fluorescence of the self-assembled coordination
polymer Cd(BTA).
In yet another exemplary embodiment of the present disclosure, the method of detecting a quencher comprising:
a. dispersing a solution of self-assembled coordination polymer Gd(BTA)
followed by sonication,
b. dissolving the quencher in an organic solvent to obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Gd(BTA); and
d. measuring the change of fluorescence of the self-assembled coordination
polymer Gd(BTA).
In still another exemplary embodiment of the present disclosure, the method of detecting a quencher comprising:
a. dispersing a solution of self-assembled coordination polymer Pr(BTA)
followed by sonication,
b. dissolving the quencher in an organic solvent to obtain a quenching solution,

c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Pr(BTA); and
d. measuring the change of fluorescence of the self-assembled coordination
polymer Pr(BTA).
The present disclosure provides a method of detecting a high energy material or a metal-containing salt or an electron-deficient analyte, the method comprising:
a. dispersing a solution of the self-assembled coordination polymer
followed by sonication,
b. dissolving the high energy material or the metal-containing salt or the
electron-deficient analyte in an organic solvent or aqueous solution to
obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer; and
d. measuring the change of fluorescence of the self-assembled
coordination polymer.
In an exemplary embodiment of the present disclosure, the method of detecting a high energy material or a metal-containing salt or an electron-deficient analyte comprising:
a. dispersing a solution of self-assembled coordination polymer of
compound Zn(BTA) followed by sonication,
b. dissolving the high energy material or the metal-containing salt or the
electron-deficient analyte in an organic solvent or aqueous solution to
obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Zn(BTA); and
d. measuring the change of fluorescence of the self-assembled
coordination polymer Zn(BTA).

In another exemplary embodiment of the present disclosure, the method of detecting a high energy material or a metal-containing salt or an electron-deficient analyte comprising:
a. dispersing a solution of self-assembled coordination polymer of
compound Cd(BTA) followed by sonication,
b. dissolving the high energy material or the metal-containing salt or the
electron-deficient analyte in an organic solvent or aqueous solution to
obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Cd(BTA); and
d. measuring the change of fluorescence of the self-assembled
coordination polymer Cd(BTA).
In yet another exemplary embodiment of the present disclosure, the method of detecting a high energy material or a metal-containing salt or an electron-deficient analyte comprising:
a. dispersing a solution of self-assembled coordination polymer of
compound Gd(BTA) followed by sonication,
b. dissolving the high energy material or the metal-containing salt or the
electron-deficient analyte in an organic solvent or aqueous solution to
obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Gd(BTA); and
d. measuring the change of fluorescence of the self-assembled
coordination polymer Gd(BTA).
In still another exemplary embodiment of the present disclosure, the method of detecting a high energy material or a metal-containing salt or an electron-deficient analyte comprising:
a. dispersing a solution of self-assembled coordination polymer of compound Pr(BTA) followed by sonication,

b. dissolving the high energy material or the metal-containing salt or the
electron-deficient analyte in an organic solvent or aqueous solution to
obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of self-
assembled coordination polymer Pr(BTA); and
d. measuring the change of fluorescence of the self-assembled
coordination polymer Pr(BTA).
The present disclosure provides a method for detecting a high energy material or a metal-containing salt or an electron-deficient analyte in a subject, the method comprising:
a. exposing the subject to the self-assembled coordination polymer of a
compound of formula 1; and
b. measuring the change of fluorescence of the self-assembled
coordination polymer to detect the high energy material or the metal-
containing salt or the electron-deficient analyte in the subject.
In an embodiment of the present disclosure, the method detects the quencher.
In another embodiment of the present disclosure, the method requires a time duration of about a few seconds to detect the quencher.
In an exemplary embodiment, the present disclosure provides a method for detecting a high energy material or a metal-containing salt or an electron-deficient analyte in a subject, the method comprising:
a. exposing the subject to the self-assembled coordination polymer of
compound Zn(BTA); and
b. measuring the change of fluorescence of the self-assembled
coordination polymer Zn(BTA) to detect the high energy material or the
metal-containing salt or the electron-deficient analyte in the subject.

In another exemplary embodiment, the present disclosure provides a method for detecting a high energy material or a metal-containing salt or an electron-deficient analyte in a subject, the method comprising:
a. exposing the subject to the self-assembled coordination polymer of
compound Cd(BTA); and
b. measuring the change of fluorescence of the self-assembled
coordination polymer Cd(BTA) to detect the high energy material or the
metal-containing salt or the electron-deficient analyte in the subject.
In yet another exemplary embodiment, the present disclosure provides a method for detecting a high energy material or a metal-containing salt or an electron-deficient analyte in a subject, the method comprising:
a. exposing the subject to the self-assembled coordination polymer of
compound Gd(BTA); and
b. measuring the change of fluorescence of the self-assembled
coordination polymer Gd(BTA) to detect the high energy material or the
metal-containing salt or the electron-deficient analyte in the subject.
In still another exemplary embodiment, the present disclosure provides a method for detecting a high energy material or a metal-containing salt or an electron-deficient analyte in a subject, the method comprising:
a. exposing the subject to the self-assembled coordination polymer of
compound Pr(BTA); and
b. measuring the change of fluorescence of the self-assembled
coordination polymer Pr(BTA) to detect the high energy material or the
metal-containing salt or the electron-deficient analyte in the subject.
The present disclosure also provides a sensor or sensor array for detection of a high energy material or a metal-containing salt or an electron-deficient analyte comprising a self-assembled coordination polymer of formula 1.

In an exemplary embodiment of the present disclosure, a sensor or sensor array for detection of a high energy material or a metal-containing salt or an electron-deficient analyte comprising a self-assembled coordination polymer Zn(BTA).
In another exemplary embodiment of the present disclosure, a sensor or sensor array for detection of a high energy material or a metal-containing salt or an electron-deficient analyte comprising a self-assembled coordination polymer Cd(BTA).
In yet another exemplary embodiment of the present disclosure, a sensor or sensor array for detection of a high energy material or a metal-containing salt or an electron-deficient analyte comprising a self-assembled coordination polymer Gd(BTA).
In still another exemplary embodiment of the present disclosure, a sensor or sensor array for detection of a high energy material or a metal-containing salt or an electron-deficient analyte comprising a self-assembled coordination polymer Pr(BTA).
The present disclosure also relates to use of a self-assembled coordination polymer of formula 1 for detection of a high energy material or a metal salt or an electron-deficient analyte.
In an embodiment, the present disclosure relates to the use of a self-assembled coordination polymer Zn(BTA) for detection of a high energy material or a metal salt or an electron-deficient analyte.
In another embodiment, the present disclosure relates to the use of a self-assembled coordination polymer Cd(BTA) for detection of a high energy material or a metal salt or an electron-deficient analyte.

In yet another embodiment, the present disclosure relates to the use of a self-assembled coordination polymer Gd(BTA) for detection of a high energy material or a metal salt or an electron-deficient analyte.
In still another embodiment, the present disclosure relates to the use of a self-assembled coordination polymer Pr(BTA) for detection of a high energy material or a metal salt or an electron-deficient analyte.
The COPs prepared above in the present study are novel systems. These materials are being used as an effective fluorimetric and colourimetric sensors for the micro detection and quantification of various explosives such as TNT, TNP etc. along with the highly selective detection of poisonous metal salts such as mercury (II). In this regard, the new COP system was prepared from the complexation reaction between Benzene tetramine and various bivalent and trivalent metal salts. The complex obtained is in the form of two-dimensional sheet-like the arrangement as confirmed from FESEM and HRTEM analysis. Zn(BTA), Cd(BTA), Gd(BTA) and Pr(BTA) were prepared and studied for their quenching efficiency.
Different nitroaromatics and non-nitroaromatics which are generally used as potent explosives were taken for the study such as Picric acid (trinitophenol, TNP), trinitro toluene (TNT), RDX, CL20, PETN along with few non-explosive nitroaromatics such as nitrophenol (NP). The quenching of fluorescence to the various extents was seen based on the quencher and concentration of quencher. With the increase in the concentration of quencher, there is a gradual decrease in the fluorescence intensity. Among these two classes of explosives, the maximum amount of quenching is observed in case of nitroaromatic systems. This is attributed to higher electron deficiency in these systems leading to stronger binding with metal leading to a decrease in emission intensity. Nitroaromatic class explosives showed higher fluorescence efficiency in comparison with the non-nitroaromatic class of explosive.

The fluorescence spectra showed high fluorescence in solution state with quantum yield as high as ~ 45%. These systems were chosen as the sensors due to their capability to exhibit high fluorescence and also the presence of electron-rich two-dimensional sheet which can act as an anchoring site for the incoming electron-deficient analytes, i.e. HEMs which leads changes (quenching ) in the fluorescence intensity.
Among all the explosives used, TNP showed the highest fluorescence quenching with all the four COP fluorophores, but the highest efficiency was seen in the case of Gd(BTA). The mechanism predominantly followed static pathway where the binding of the quencher to the metal centre in the fluorophore brought the quenching in fluorescence. COPs described in the present application act as explosive detectors with very high efficiency along with very low detection limit suitable for the practical applications.
The COPs used in this study contains the metal centres belonging to d10 and lanthanide series, which are regarded as big molecules. This makes their conduction and valence bands behave similar to that of molecular orbitals. It is well-established phenomena in these kinds of systems that the electron transfer occurs between the HOMO of electron-rich COP to LUMO of electron-deficient HEMs. This difference acts as a driving force for the electron transfer between these electron-rich and electron-deficient species. Higher the difference, greater will be the quenching.
Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in the art based upon description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods/steps and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for examples illustrating the above-described embodiments, and in order to illustrate the embodiments of the present disclosure, certain aspects have been employed. The examples used herein for such

illustration are intended merely to facilitate an understanding of ways in which the embodiments herein may be practised and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.
EXAMPLES
Example 1:
A solution of 150 mg (1 eq.) of metal salt (zinc acetate, cadmium acetate, Gadolinium acetate and Praseodymium acetate) in 25 mL of water and 1 mL of concentrated aqueous ammonia (NH4OH, 14 mol L -1) was added to a solution of 1,2,4,5, Benzene tetraamine.4 HCl (BTA) (1.5 eq.) in 20 mL of water. This mixture was stirred in a round bottom flask for four hours. The resulting powder was centrifuged, filtered, washed with water and ethanol and air-dried. And further dried under vacuum at about 100°C for 2 hours to obtain the compound of formula I (COPs), i.e. self-assembled coordination polymers.
Molecular structural characterization:
FTIR spectra were recorded for all the COPs synthesized and were compared with that of the amine (Figure 1). Free amine NH stretching at 3360 cm-1 and 3385 cm-1 as a doublet due to symmetric and asymmetric modes respectively were observed in the case of amine ligand i.e. BTA (Figures 1 a-d, blue trace). A broadening of N-H stretching peak was observed around 3415 cm-1, which is shifted to higher frequency w. r. to BTA, indicates the linking/interaction between metal and the nitrogen during the complexation process (Figures 1 a-d, red trace). This is additionally supported by the presence of two peaks in the COPs at about 430 and 540 cm-1 which are not found in the benzene tetramine (BTA) and corresponds to the M-N and M-O vibration bands respectively (figures 1 a-d, red trace).
Raman spectra were recorded to further corroborate the results about bonding obtained in IR as well as to shed some light into the formation of two-dimensional structure. Figure 2 shows the prominent band around 440 cm-1 seen in the far IR

region of these COPs. (Figures. 2 a-d) relates to ligand coordination to the metal centre, the M-N stretch; the bands present around 1380 cm-1 and 1560 cm-1 corresponds to D and G bands respectively. These are generally seen in the graphitic carbon systems. Larger G band in comparison to D band can be attributed to the presence of larger amorphous nature in the system. The broad occurrence of 2D/G band around 2800 cm-1 indicates the presence of layered structure and the wideness and presence of multiple sub-bands confirm the presence of multiple layers in the system and broadens the 2G band which gives information about the presence of extended SP2 lattice in the system.
UV-Vis spectra of the samples were recorded in the solution phase upon dispersing them in the DMF. As shown in Figures 3a & 3b respectively, Zn and Cd COPs showed similar absorption pattern with a single peak centred on 470 nm whereas the spectra of both lanthanide complexes i.e. Gd(BTA) and Pr(BTA) exhibited two peaks centred on 480 nm and another around 320 nm (Figures 3c & 3d). The bandgap was calculated using the relation Eg = 1240/ λonset, and the values are tabulated in Table 1. The band gaps are found to be in the range of 2.1 to 2.4 eV

The formation of COPs was monitored using XRD, and the patterns are given in Figure 4. The COPs exhibit partially crystalline structures. Being two-dimensional sheet/layered like structures, they didn’t exhibit higher crystallinity and showed some short-range ordering as can be inferred from PXRD. Zn(BTA) (Figure 4a) showed higher crystallinity with multiple peaks in the low and wide-angle regions,

and similarly, the other d10 system analogue Cd(BTA) also showed highly crystalline lattice arrangement in its structure as shown in Figure 4b. But interestingly, both the lanthanide COPs exhibited nearly amorphous/ poorly crystalline lattice structure as can be seen from the PXRD profiles of the COPs Gd(BTA) (Figure 4c) and Pr(BTA) (Figure 4d). Gd(BTA) (Figure 4c) showed wide peaks in both low and wide-angle with few sharp reflections possibly due to diffused diffraction arising from less ordered 2D lattice. As can be seen from the Figure 4d, the PXRD profiles of the COP Pr(BTA) reveal total lack of crystallinity in the structure which can be evidenced by the observation of diffused peaks in profile devoid of any sharp diffraction.
The XPS analysis of the four COPs is given in Figures 5-8. The survey scan (Figures 5a, 6a, 7a & 8a) shows the different elements which are present in the COPs. The presence of oxygen other than nitrogen, metal and carbon is attributed to the presence of water attached to the vacant coordination sites of the COPs. The deconvolution of the carbon region (C 1s) (Figures 5b, 6b, 7b & 8b) gives information about the presence of different kinds of environment in which the carbon is present. As it is well known that the XPS binding energy values vary with change in the surrounding chemical environment. The carbon region was resolved into two main peaks corresponding to C=C and C-N groups. The C=C is the one with a larger peak area, indicates the majority of carbon present in C=C form rather than C-N, which is clear from the molecular formula. As can be seen in the Figures 5c, 6c, 7c & 8c, nitrogen peak (N 1s) can also be resolved into two peaks which can be attributed to N-H and M-N bonds. The observation of two peaks in the nitrogen region corresponding to two kinds of the environment is absent in case of COPs Gd(BTA) (Figure 7c) and Cd(BTA) (Figure 6c) where a single broad peak is observed in this region. The COPs Zn(BTA) and Pr(BTA) exhibits variable metallic oxidation state, where the metal existed in different oxidation states. In case of Zn(BTA), (Figure 5d) it’s clear that the metal existed in Zn (II) and Zn (0) states whereas in case of Pr(BTA), Pr existed in Pr (III) and Pr (0) states (Figure 8d). This behaviour was not seen in case of Cd and Gd COPs where only one

oxidation state Cd (II) and Gd (III) respectively are seen (Figures 6d & 7d respectively).
FESEM and HRTEM studies were carried out on all the four COPs prepared so as to confirm the possible two-dimensional structure predicated by spectroscopic techniques. The sample was dispersed in water and drop cast on to silica substrate and Cu grid for FESEM and HRTEM measurements respectively. Figure 9 shows the low magnification FESEM images of the COPs. All the compounds seem to exhibit layered or sheet-like arrangement, and multiple layers stacked one above the other can be clearly seen. The nano-sheets are of the size few nanometers to a few hundred nanometers. Further to confirm these results, HRTEM was recorded and are shown in Figure 10. The high-resolution images supported the occurrence of nanosheet arrangement where the few layers are arranged in a stalked manner. The single-layer thickness roughly scales up to a few nanometers.
The EDAX experiment was carried out to confirm and validate the elements present in the COPs and also to determine the elemental composition of the COPs. The EDAX was recorded along with the FESEM studies. The results obtained are shown in Figure 11. As expected, the COPs formed with different metals exhibited the signals corresponding respective metals for example Zn(BTA) (Figure A) showed Zn metal along with the other elements such as carbon, nitrogen and oxygen. The inset (a) consists of the table which depicts the elemental composition present in these systems. The other inset, i.e. inset (b) shows the highlighted region FESEM image, which was the area used for EDAX recording.
All the four COPs invariably exhibited fluorescence emission in solution state upon irradiation with UV light of suitable wavelength for excitation. Figure 12 depicts the emission spectra of different COPs dispersed in DMF. In case of Zn(BTA) (Fig 12a) and Cd(BTA) (Fig 12b) which are d10 systems, fluorescence mainly arises due to the interaction of backbone pi electrons of the sp2 hybridised ligand system and the metal centres. Metal to ligand charge transfer (MLCT) and ligand to metal charge (LMCT) transfers are also playing an important role. But specifically, in

case of d10 systems, LMCT is the primary reason for the fluorescence where the emission arises due to the charge transfer from exited ligand orbitals to the metal orbitals in the ground state. In case of Gd(BTA) and Pr(BTA) (Figures 12c &12d respectively) where both the metal centres belong to lanthanide series, the fluorescence occurs due to the phenomena referred to as antenna effect also known as sensitization of metal centred complex. In these complexes, the energy which was absorbed by the organic pi-conjugated ligand is transferred onto these Ln (III) (Gd (III) and/or Pr(III)) excited states. The energy migration happens via the long-lived triplet state of the ligand. Since these Ln(III) ions are good quenchers of triplet states, phenomena of photobleaching are considerably reduced. The interaction of the ligands and also the metal centres with other organic or inorganic systems in the surrounding environment greatly affects the transition and hence varying the fluorescence which is the primary reason for variation in the emission with varying the solvent polarity. This property was employed for the detection of different electron-deficient nitroaromatics. The nitro aromatics being electron deficient in nature have the capability to bind to the electron-rich aromatic ligand system.
To determine the efficiency of emission, the quantum yield was calculated for all the samples. Relative quantum yield technique was used for the determination of quantum yield. Fluorescence sodium dissolved in water was used as an internal standard. The known amounts (2mg in 10 ml) of COPs were dispersed in DMF and absorption, and emission spectra were subsequently recorded. A plot consisting of emission intensity v/s absorption intensity was obtained, as shown in Figure 13. The slope (gradient) obtained from this plot was used for the calculation of relative quantum yield using the formula given below.

Φx – Quantum yield of the unknown sample (COP)
Φstd- Quantum yield of the standard (fluorescence sodium)
Gradx – slope/gradient obtained for the plot of the unknown sample (COP)

Gradstd – slope/gradient obtained for the plot of Standard sample (fluorescence sodium)
η2x – refractive index of the solvent used for standard
η2std – refractive index of the solvent used for COPs.
Using the aforementioned formula, the quantum yields were calculated and shown in table 2. The quantum yields for the different COPs were in the range of 16-50%. Consistently higher quantum yield was seen in case of lanthanide COPs i.e. Gd(BTA) and Pr(BTA), but in case of d10 metal ion-based COPs, Zn(BTA) showed highest quantum yield whereas its analogue Cd(BTA) showed remarkably lower quantum yield as compared to Zn(BTA).

Table 2: Relative quantum yield calculated for the COPs using fluorescence sodium as standard.
Example 2
Quenching studies
The quenching experiments were carried out on the dispersed solutions of COPs in acetone. The sample was taken in a known amount of acetone and sonicated for 3 hours to obtain a homogeneously dispersed system which can be used for further studies. The known quantities of quenchers were dissolved in acetone to obtain quenching solution of the desired concentration and used for the quenching titration with the fluorophore COP. The excitation for the fluorescence was obtained from the Lambda max of the UV-Vis spectroscopy for the COP.
Stern Volmer (SV) plot obtained by plotting I0/I v/s concentration gave information about the type of mechanism involved. From the literature, it is a well known fact

that mainly two kinds of mechanisms are possible in these types of systems. Both involve electron transfer mechanism and viz; static and dynamic quenching. Static quenching generally happens when the electron transfer occurs between ground state fluorophore and quencher and in case of dynamic quenching, the electron transfer happens between fluorophore in the excited state and the quencher. A linear SV plot indicates the presence of either static or dynamic quenching alone, but an upward curving SV plot at higher concentration indicates the possible coexistence of both these quenching pathways.
Since the dynamic quenching occurs via diffusion-controlled collision, it’s also known as collisional quenching, and equation one can be applied to this system.
I0/I = 1 + KD[Q] eqn 1
Where I0 and I are fluorescence intensities and KD is dynamic quenching constant. Similarly, the static quenching can be expressed using the equation 2 and 3
I0/I = eVq[Q] eqn 2
I0/I = 1 + Ks[Q] eqn 3
Where eqn 2 corresponds to an effective sphere quenching model and eqn 3
explains ground state non-fluorescent quenching model. But at very low
concentration of quenchers eVq[Q] = 1 + Vq[Q], hence equation 3 can be
approximated as equation 2 and the simultaneous static and dynamic quenching can be given in equation 4.
I0/I = (1 + Ks[Q]) (1 + KD[Q]) eqn 4
In case of linear curve i.e. only one kind of quenching mechanism is prominent, wherein the linear curve is fitted to obtain slope which gives information about the quenching constant which sheds light on the quenching efficiency. But when a non-linear profile which is arising due to the combination of both mechanisms, a linear regression method will be employed to determine the quenching constant.

Different nitroaromatics and non-nitroaromatics which are generally used as potent explosives were taken for the study such as Picric acid (trinitrophenol, TNP), trinitrotoluene (TNT), RDX, CL20, PETN along with few non-explosive nitroaromatics such as nitrophenol (NP). The quenching of fluorescence to the various extents was seen based on the quencher and concentration of quencher. With the increase in the concentration of quencher, there was a gradual decrease in the fluorescence intensity. To study the steady-state fluorescence quenching, it was subjected to a linear regression analysis using the Stern–Volmer equation. The analysis of the Stern-Volmer plot will give brief information about the type of quenching mechanism involved. The mechanism is thought to be the electron transfer of the electron-deficient quencher and electron-rich metal centre. This interaction will disrupt the ligand to metal charge transfer phenomena which are responsible for the fluorescence emission. The dependency of quenching efficiency on the electron-withdrawing power of the quencher also supports this hypothesis of electron transfer.
The known amount (3-4 mg) of the sample was dispersed in DMF, and the same was used for the fluorescence measurements. Known concentration nitroaromatics were prepared by carefully dissolving required amount into acetone. Further, fluorimetric titration was carried out by adding a known amount of nitroaromatics into the fluorophores, and the fluorescence response was recorded. The corresponding fluorescence spectra were shown in Figures 14, 15, 16 & 17.
a) Quenching of fluorescence in Zn(BTA)
The fluorescence quenching was carried out for the sample Zn(BTA) by employing the same procedure as mentioned above. Six different explosive systems were used for the quenching studies among which three viz; trinitrophenol (picric acid, TNP), p-nitrophenol (PNP) & trinitrotoluene (TNT) which are nitroaromatic explosives, whereas RDX, PETN and CL20 which are non-nitroaromatic explosives were also used. The quenching profile obtained is shown in Figure 14 a-f. Among these two

classes of explosives, the maximum amount of quenching is observed in case of nitroaromatic systems. This is attributed to higher electron deficiency in these systems leading to stronger binding with metal, leading to a decrease in emission intensity. Ksv (quenching efficiency) were obtained with the help of Stern-Volmer plots (Figures 14 g-l) for each of the quenchers used, and among all the quenchers, TNP showed highest quenching efficiency followed by PNP and TNT. The higher value of quenching efficiency is observed for TNP in all the different COP fluorophore used. The possible mechanism is described in detail in the later section. The Stern-Volmer plot showed straight line at the lower concentration corresponding to the presence of static quenching process arising due to the binding of quencher with the fluorophore and nonlinear region at a higher concentration which accounts for the presence of both static and dynamic (collisional) quenching.
b) Quenching of fluorescence in Cd(BTA)
To compare the effect of metal ion in the quenching phenomena, another d10 system, Cd(BTA) was probed for its potential quenching ability. As expected, this also showed similar kind of quenching pattern with nitroaromatic and non-nitroaromatic quenchers as seen in Zn(BTA) (Figs 15 a-f). But interestingly, the quenching efficiency determined for TNP and PNP were close to each other. In fact, PNP showed a higher quenching efficiency than TNP. The overall quenching efficiency was decreased as compared to that observed in the case of Zn(BTA). This decrease in Ksv value leading to a decrease in efficiency is attributed to the weakened binding of nitroaromatics in case of Cd(BTA), which is further confirmed with the determination of binding constant. The Stern-Volmer plots (Figures 15 g-l) of non-nitroaromatics systems exhibited a non-linear behaviour in both higher and lower concentration with very low Ksv value suggesting the lower binding capability of these explosives with the Cd(BTA) COP and also it suggests the small amount of quenching which is seen primarily arising due to the dynamic quenching, i.e. collision of the excited fluorophore with quencher molecules.
c) Quenching of fluorescence in Gd(BTA)

Apart from the d10 systems, the lanthanide metal-based COP, Gd(BTA) are also probed for their emission quenching properties and are shown in Figures 16 a-f. Similar explosive quenchers which are used in the quenching study of aforementioned complexes were used. Interestingly, the quenching efficiency was quite higher for nitroaromatic explosives, especially the TNP, showed overall highest quenching efficiency among all the COPs, as shown in table 3. Even non-nitroaromatic explosives showed higher quenching efficiency in comparison with other COPs. The Stern-Volmer plots (figure 16 g-l) showed distinctive static quenching (due to binding of quencher to the fluorophore) at low concentration and a mixture of both static and dynamic (collisional) quenching at a higher concentration as expected.
d) Quenching of fluorescence in Pr(BTA)
The comparative analysis of lanthanide COPs was done with the preparation of analogous lanthanide complex containing Praseodymium as a metal ion. The same was used as the fluorophore for quenching studies. The protocol and the explosives used were similar to those discussed before. The quenching of fluorescence by these explosive systems in the case of Pr(BTA) fluorophore are plotted in Figures 17 a-f. A similar trend which is observed in the other lanthanide COP was seen in this system, i.e. the nitroaromatic explosives (TNP, TNT and PNP) showed a higher degree of fluorescence quenching in comparison with that of non-nitroaromatic explosives (RDX, PETN and CL20). Among the non-nitroaromatic, TNP (picric acid) showed the higher quenching efficiency as shown in table 3, but in comparison with Gd.BTA, the quenching efficiency was lower which is due to weaker binding in Pr(BTA) as explained later. Stern-Volmer plot (Figures 17 g-l) showed similar mechanism as was seen in the case of Gd(BTA), i.e. static quenching dominating in the lower concentration regime and mixture of static and dynamic mechanisms contributing towards quenching as the concentration was increased.
Overall, four COPs were probed for their fluorescence quenching properties in the presence of electron-deficient explosive systems. The comparative fluorescence quenching efficiency was tabulated in Table. 3 Figure 18 gives the

comparative account of the efficiency of various quenchers in different COP fluorophore. From Figure 18 and Table 3, it can be inferred that the nitroaromatic class explosives showed higher fluorescence efficiency in comparison with a non-nitroaromatic class of explosive. Among all the explosives used, TNP showed the highest fluorescence quenching with all the four COP fluorophores, but the highest efficiency was seen in the case of Gd(BTA). The mechanism predominantly followed static pathway where the binding of the quencher to the metal centre in the fluorophore brought the quenching in fluorescence.



The sensitivities/LOD (limits if detection) of the quenchers (TNP and TNT) towards these COPs were determined using fluorescence titrations at low concentrations. Percentage quenching was plotted against quencher concentration (Figure 19) and the concentration at which there is a sharp increase in the quenching percentage was used to calculate the limit of detection and the values thus calculated are tabulated in Table 4. The sensitivity value clearly shows the higher sensitivity towards TNP, which is invariably observed in all the COPs probed. The Gd(BTA) showed sensitivity with the detection limit as low as 0.1 µM for TNP (Figure 19e). It is interesting to note that the same COP Gd(BTA) showed highest quenching efficiency for TNP quencher (Table 3). The sensitivity towards TNT was also good though lesser than that of TNP; the detection limit as low as 1.5 µM was seen a case of Zn(BTA). These COPs synthesized acts as explosive detectors with very high efficiency along with very low detection limit suitable for the practical applications.
As described in the previous sections, Stern-Volmer plots provide information about the type of quenching mechanism/pathways involved based on the nature of the curve. These mechanisms are further validated with the help of combined aspects of spectroscopic and theoretical methods. Benesi-Hildebrandt (BH) plots are obtained by carrying out the complexation titrations of COPs with the quencher TNP; the increase in the absorbance intensity upon the addition of quenchers for different COPs was observed. This observation is attributed to the fact that the added quencher TNP will irreversibly bind to the metal centre, the phenomena which was observed even in the Stern-Volmer plot. Figure 20 shows the BH plot

for the different COP fluorophores interacting with TNP. The plots were arrived at using the BH equation for non-bonding interactions as given below. The slope of the plot is used to determine the binding constant, which is tabulated in Table 5. The binding constant is highest for Gd(BTA) and lowest for Cd(BTA) which is in agreement with the fact that the same trends were observed for the Ksv values as well as quenching efficiency. This confirms the possible static quenching, i.e. binding of the quencher with the metal centre and also explains the fact that as the binding increases the increase in the quenching is observed.
The selectivity towards TNP as compared with the other quenchers exhibited by all of the COPs was further analyzed with the help of theoretical calculations. The COPs used in this study contains the metal centres belonging to d10 and lanthanide series, which are regarded as big molecules. This makes their conduction and valence bands behave similarly to that of molecular orbitals. It is well-established phenomena in this kind of systems that the electron transfer occurs between the HOMO of electron-rich COP to LUMO of electron-deficient HEMs. This difference acts as a driving force for the electron transfer between these electron-rich and electron-deficient species. Higher the difference, greater will be the quenching. To understand this difference, the HOMO and LUMO values of the quenchers were determined using DFT calculations. The lower LUMO value of TNP shows the higher possibility of electron transfer (binding) which gives the higher selectivity towards TNP, which was observed during the experiments. Hence, it is worth mentioning here that the lower LUMO value in case of TNP facilitates the electron transfer and hence forming a stronger complex with COPs and subsequently quenching fluoresce strongly (Figure 21).
Along with the quenching studies for the detection/sensing of explosives, the COP fluorophores were also used for the detection and quantification of different metal salts. For this experiment, a similar kind of fluorescence titration was employed as explained in the earlier section where the quencher is replaced from explosives to metal salts. A known concentration of the aqueous metal salt solution was prepared by dissolving the accurately weighed metal salts in water, and the same was used for sensing

experiments. Figure 22 shows the quenching of fluorescence realized by using differen metal salts with different COPs. Among the two classes of COPs used, the ones whic are consisting of d10 metal centres (Cd(BTA)) showed higher efficiency and sensitivit towards metal ion sensing, and hence those results are only discussed below.
As can be seen from Figure 22, it is clear that the metal salts invariably quench the fluorescence exhibited by these COPs, but the efficiency and extent of fluorescence vary with varying the metal salts. Among all the metal salts used across different COPs, Hg2+ (mercuric) ion shows the highest efficiency, i.e. the quenching is highest in the case of mercuric salt as compared with the other salts. With the understanding of this differential quenching efficiency, mercuric salt was specifically selected to study its quenching ability in detail. Figure 23 shows the plots depicting the fluorescence quenching phenomena observed with aqueous mercuric salt as a quencher. The Ksv was calculated with the help of SV equation as discussed before (Figure 24). The Ksv values and quenching efficiency at the highest concentration are tabulated in Table 5.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in the art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and

modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practised with modification within the spirit and scope of the embodiments as described herein.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

We Claim:
1. A self-assembled coordination polymer of formula I

2. The self-assembled coordination polymer as claimed in claim 1, wherein the metal is selected from a group comprising Zinc, Cadmium, Gadolinium and Praseodymium.
3. The self-assembled coordination polymer as claimed in claim1, wherein the aryl


4. A process for preparing a self-assembled coordination polymer as claimed in claim 1, wherein the process comprising reacting metal salt with aryltetramine or salts of aryltetramine in presence of an aqueous alkali.
5. The process as claimed in claim 4, wherein the metal salt is selected from a group comprising Zinc acetate, Cadmium acetate, Gadolinium acetate and Praseodymium acetate.
6. The process, as claimed in claim 4, wherein the aryltetramine is 1,2,4,5-benzenetetramine.
7. The process, as claimed in claim 4, wherein the salts of aryltetramine is 1,2,4,5-benzenetetramine tetrahydrochloride.
8. The process, as claimed in claim 4, wherein the aqueous alkali is aqueous ammonia.
9. The process as claimed in claim 4, wherein the process is carried out at a temperature ranging from about 25 °C to about 30 °C and for a time period ranging from about 1 hour to about 4 hours.
10. The process as claimed in claim 4, wherein at least one of the reactants aryltetramine or salts of aryltetramine and metal salt intrinsically support fluorescence.

11. A process for preparing the self-assembled coordination polymer as claimed in claim 1, wherein the process comprising step of reacting metal salt with 1,2,4,5-benzenetetramine tetrahydrochloride in presence of aqueous ammonia.
12. A method of detecting a quencher, the method comprising:
a. dispersing a solution of self-assembled coordination polymer as claimed in claim one followed by sonication,
b. dissolving the quencher in an organic solvent to obtain a quenching
solution,
c. titrating the quenching solution with the dispersing solutions of
self-assembled coordination polymer; and
d. measuring the change of fluorescence of the self-assembled
coordination polymer.
13. The method as claimed in claim 12, wherein the quencher is selected from a group comprising a high energy material, a metal-containing salt, an electron-deficient analyte and combinations thereof.
14. The method, as claimed in claim 12, wherein the high energy material comprises one or more nitro (-NO2) groups.
15. The method as claimed in claim 12, wherein the high energy material is selected from a group comprising picric acid (trinitrophenol, TNP), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), 2,3-dimethyl-2,3-dinitrobutane (DMNB), hexanitrohexaazaisowurtzitane (CL20), pentaerythritol tetranitrate (PETN) and cyclo-trimethylene-tri nitramine (RDX).
16. The method as claimed in claim 12, wherein the metal-containing salt is selected from a group comprising mercury salt, silver salt, cupric salt,

cuprous salt, sodium salt, ammonium salt, nickel salt, zinc salt and combinations thereof.
17. The method as claimed in claim 12, wherein the electron-deficient analyte is p-nitrophenol.
18. A method of detecting a high energy material or a metal-containing salt or an electron-deficient analyte, the method comprising:
a. dispersing a solution of self-assembled coordination polymer as claimed in claim 1 followed by sonication,
b. dissolving the high energy material or the metal-containing salt or
the electron-deficient analyte in an organic solvent or aqueous
solution to obtain a quenching solution,
c. titrating the quenching solution with the dispersing solutions of
self-assembled coordination polymer; and
d. measuring the change of fluorescence of the self-assembled
coordination polymer.
19. A method for detecting a high energy material or a metal-containing salt or
an electron-deficient analyte in a subject, the method comprising:
a. exposing the subject to the self-assembled coordination polymer as
claimed in claim 1; and
b. measuring the change of fluorescence of the self-assembled
coordination polymer to detect the high energy material or the
metal-containing salt or the electron-deficient analyte in the
subject.
20. A sensor or sensor array for detection of a high energy material or a metal
containing salt or an electron deficient analyte comprising a self-assembled
coordination polymer of claim 1.

21. Use of a self-assembled coordination polymer as claimed in claim 1 for detection of a high energy material or a metal salt or an electron-deficient analyte.