1. A microwave assisted method for synthesizing nitrogen enriched triaminopyrimidine based imine linked organic polymer for use in safe and long-term radioactive iodine sequestration, comprising steps: a) Mixing 2,6-pyridinedicarboxaldehyde (3 mmol, 0.405 g) and 2,4,6-triaminopyrimidine (2 mmol, 0.250 g) in a solvent in a microwave vial; b) Dissolving the reaction mixture completely under sonication; c) Sealing the microwave vial and placing it in a microwave reactor at 80 °C for 60 minutes under microwave irradiation power of 80 W; d) Filtering the resulting precipitate; e) Washing the obtained precipitate with excess of acetone; and f) Drying the obtained product under vacuum at 80 °C for 2h.

2. The method as claimed in claim 1, wherein the solvent is DMF.

3. The method as claimed in claim 1, wherein the obtained yield of the organic polymer is 72%.

4. The method as claimed in claim 1, wherein the synthesis results in no or minimal side products.

5. The method as claimed in claim 1, wherein the organic polymer is characterized by thermogravimetric analysis indicating thermal stability up to 400°C.

6. The method as claimed in claim 1, wherein the organic polymer has wide applications in nuclear waste management, environmental remediation, iodine sequestration and carbon sequestration.

7. The method as claimed in claim 1, wherein the organic polymer has ample p-electron rich arenes and nitrogen centres which facilitates efficient interaction with iodine.

Description:FIELD OF INVENTION
The present invention generally relates to the field of Polymer chemistry, green chemistry and nuclear waste management. More particularly, the present invention pertains to microwave assisted synthesis of 2,4,6-triamionopyrimidine based nitrogen enriched imine linked organic polymer (TAP-NEILOP_MW).

BACKGROUND OF THE INVENTION
Traditional methods of synthesizing functional polymers involve the use of toxic solvents, prolonged heating, harsh chemical conditions and energy-intensive conditions. These methods not only increase production costs but also contribute to environmental pollution and carbon emissions.

Z. Alsudairy, N. Brown, C. Yang, S. Cai, F. Akram, A. Ambus, C. Ingram, X. Li, Facile microwave-assisted synthesis of 2D imine-linked covalent organic frameworks for exceptional iodine capture, Precision Chemistry. 1 (2023), 233-240. Alsudairy et al. have synthesized two novel 2D imine-linked covalent organic frameworks (Mw-TFB-BD-X, X= -CH3 and -OCH3) through Schiff-base condensation between 1,3,5-triformylbenzene and substituted benzidine derivatives in acetonitrile solvent through microwave-assisted method at 90 °C in 1h. The application area of the work was capture of radioactive iodine.

J. Zhao, J. Li, W. Cao, S. Du, T. Hu, X. Chen, F. Luo, G. Du, Y. Zhang, Y. Yang, S. Shan, Microwave-assisted rapid synthesis of novel nitrogen-rich covalent organic frameworks for Ibuprofen removal from aqueous solution, Russ. J. Phys. Chem. 98(2024), 2070-2083. Zhao et al. have constructed a novel covalent organic framework SNW-1 through Schiff-base reaction between terephthaldehyde and melamine in DMSO utilizing microwave-assisted method at 180 ºC, 50W power for 0.5h. The application area of the work was removal of Ibuprofen from aqueous solution.
US10260148B2 describes porous materials—such as metal-organic frameworks (MOFs) and porous organic polymers (POPs)—that exhibit reactivity with, or sorptive affinity for, electronic gases. These materials are designed to effectively remove or reduce electronic gases from effluent streams, eliminate contaminants from electronic gas flows to enhance their purity, or capture trace mercury contaminants in hydrocarbon streams to improve hydrocarbon purity. MOFs are coordination compounds formed between metal ions and multidentate organic ligands, while POPs result from the polymerization of organic monomers.

Green chemistry has emerged as a powerful approach to designing safer and more sustainable chemical processes. Microwave assisted synthesis is a promising green technique, offering rapid reaction rates, reduced solvent usage and no or less side products.

Therefore, there remains a need for improved and greener synthesis route that reduces the environmental footprint and aligned with demands for sustainability. The present invention contributes to environmentally friendly practices. The present invention provides a novel, microwave assisted synthetic process for the preparation of organic polymer.

OBJECT OF THE INVENTION:
To address the foregoing problems, in whole or in part, and/or other problems that may have been observed by persons skilled in the art, the present disclosure provides compositions and methods as described by way of example as set forth below.

The principal object of the present invention is to provide a microwave assisted synthesis method of an organic polymer.

Another object of the present invention is to provide a microwave assisted synthesis method of 2,4,6-triaminopyrimidine based nitrogen enriched imine linked organic polymer.

Yet another object of the present invention is to provide an ultrafast microwave-assisted approach for synthesis of 2,4,6-triaminopyrimidine based nitrogen enriched imine linked organic polymer (TAP-NEILOP_MW) using Schiff base polycondensation reaction of 2,6-pyridinedicarboxaldehyde and 2,4,6-triaminopyrimidine.

Yet another object of the present invention is to apply green chemistry principles, including solvent reduction and energy efficiency, to the synthesis process.

Yet another object of the present invention is to demonstrate the environmental advantages of the present method over conventional polymerization.

SUMMARY OF THE INVENTION
This summary is intended to introduce, in simplified form, a selection of concepts that are further described in the detailed description. This summary is merely presented as a brief overview of the subject matter described and claimed herein and does not aid in determining the scope of the claimed subject matter.

The present invention provides a microwave assisted synthesis route for preparing organic polymer based on known monomer systems for use in iodine absorption.

In one aspect, the present invention provides a microwave assisted synthesis route for preparing 2,4,6-triaminopyrimidine based nitrogen enriched imine linked organic polymer (TAP-NEILOP_MW), as represented by Formula I:

Formula I
In another aspect, the present invention provides a microwave assisted synthesis method to synthesize compound of Formula I using 2,6-pyridinedicarboxaldehdye (represented by Formula II) and 2,4,6-triaminopyrimidine (represented by Formula III):

Formula II Formula III

In yet another aspect, the present invention provides a method of synthesizing 2,4,6-triaminopyrimidine based nitrogen enriched imine linked organic polymer (TAP-NEILOP_MW), wherein the method comprising following steps:
a) Mixing 2,6-pyridinedicarboxaldehyde and 2,4,6-triaminopyrimidine in a solvent in a microwave vial;
b) Dissolving the reaction mixture completely under sonication;
c) Sealing the microwave vial and placing it in a microwave reactor at 80±2 °C for 60 minutes under microwave irradiation power of 80 W;
d) Filtering the resulting precipitate;
e) Washing the obtained precipitate with excess of acetone; and
f) Drying the obtained product under vacuum at 80 °C for 2h.

In yet another aspect, the present invention provides that the solvent used in the microwave assisted synthesis of 2,4,6-triaminopyrimidine based nitrogen enriched imine linked organic polymer (TAP-NEILOP_MW) is DMF.

In yet another aspect, the present invention provides an environmentally friendly synthesis method for imine linked organic polymer that exhibits wide applications in nuclear waste management, environmental remediation, iodine sequestration and carbon sequestration owing to its nitrogen rich sites.

BRIEF DESCRIPTION OF THE DRAWINGS
In order to facilitate a comprehensive understanding and practical implementation of the disclosure, reference will now be made to exemplary embodiments illustrated in the accompanying figures. The figures together with detailed description below, are incorporated into 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:

FIG. 1(a) illustrates FTIR spectra of 2,4,6-triaminopyrimidine (TAP), 2,6-pyridinedicarboxaldehyde (PDA) and TAP-NEILOP_MW, and (b) Powder XRD pattern of TAP-NEILOP_MW.
FIG. 2 illustrates TGA thermogram of TAP-NEILOP_MW in N2 atmosphere.
FIG. 3 illustrates Schematic microwave assisted synthesis route of TAP-NEILOP_MW.
FIG. 4 illustrates (a) FESEM images of TAP-NEILOP_MW and (b) EDX spectrum of selected area of the materials shown in FESEM image with yellow rectangle.

DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention provides a novel method for the synthesis of 2,4,6-triaminopyrimidine based nitrogen enriched imine linked organic polymer (TAP-NEILOP_MW).

The present disclosure can be understood more readily by reference to the following description, taken in conjunction with the accompanying Figures and Examples, all of which form a part of this disclosure.

At the very outset of the detailed description, it may be understood that the ensuing description only illustrates a particular form of the invention covered in the present disclosure. However, such a particular form is only an exemplary embodiment, and without intending to imply any limitation on the scope of the invention. Accordingly, the description is to be understood as an exemplary embodiment and teaching of invention and not intended to be taken restrictively.

Before the present disclosure or methods of the present disclosure are described in greater detail, it is to be understood that the specific products, methods, processes, conditions or parameters, are not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the methods. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the methods. Certain ranges are presented herein with numerical values being preceded by the term “about.” The term “about” is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. For example, "about" can mean within one or more standard deviations, or within ± 30%, 25%, 20%, 15%, 10% or 5% of the stated value.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods and materials are described. For the purposes of the present invention, the following terms are defined below.

It is appreciated that certain features of the methods, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the methods, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. All combinations of the embodiments are specifically embraced by the present invention and are disclosed herein just as if each and every combination was individually and explicitly disclosed, to the extent that such combinations embrace operable processes and/or composites/scaffolds.

The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

As used herein, the term "comprises", "comprising", or “comprising of” is generally used in the sense of include, that is to say permitting the presence of one or more features or components. The term "comprises", "comprising", or “comprising of” when placed before the recitation of steps in a process or method means that the process or method encompasses one or more steps that are additional to those expressly recited, and that the additional one or more steps may be performed before, between, and/or after the recited steps.

Reference throughout this specification to “certain embodiments”, “further embodiments”, “specific embodiments”, “further specific embodiment”, “one embodiment”, “a non-limiting embodiment”, “an exemplary embodiment”, “some instances”, or “further instances”, means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure.

As used herein, the terms ‘include’, ‘have’, ‘comprise’, ‘contain’ etc. or any form of said terms such as ‘having’, ‘including’, ‘containing’, ‘comprising’ or ‘comprises’ are inclusive and will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illustrate the disclosure and does not pose a limitation on the scope of the disclosure otherwise claimed.

As used herein, the term “invention”, “present invention”, “disclosure” or “present disclosure” as used herein is a non-limiting term and is not intended to refer to any single embodiment of the particular invention but encompasses all possible embodiments as described in the specification.

The terms “process(es)” and “method(s)” are considered interchangeable within this disclosure.

For convenience, certain terms used in the specification and examples are collected in this section below:
TAP-NEILOP_MW: 2,4,6-Triaminopyrimidine based Nitrogen Enriched Imine Linked Organic Polymer (via microwave assisted synthesis method)
DMF: N,N- Dimethylformamide
mmol: millimoles
PDA: 2,6-pyridinedicarboxaldehyde
TAP: 2,4,6-triaminopyrimidine
FTIR: Fourier Transform Infrared
PXRD: Powder X-Ray Diffraction
TGA: Thermogravimetric analysis

In one specific embodiment, the present invention provides a novel method for synthesis of 2,4,6-Triaminopyrimidine based Nitrogen Enriched Imine Linked Organic Polymer of Formula I:


Formula I

In an embodiment, the imine linked polymer of Formula I is synthesized using microwave assisted synthesis route and readily available monomers.

In an embodiment, 2,4,6-Triaminopyrimidine based nitrogen enriched imine linked organic polymer is prepared via Schiff base polycondensation reaction between two compounds i.e. 2,6 pyridinedicarboxaldehyde and 2,4,6-triaminopyrimidine represented by Formula II and Formula III respectively.

Formula II Formula III

In an embodiment, schiff base polycondensation reaction between 2,6 pyridinedicarboxaldehyde and 2,4,6-triaminopyrimidine is provided in scheme 1.

In an embodiment, the schematic chemical illustration for the ultrafast microwave-assisted synthesis of TAP-NEILOP_MW is given as follows in scheme 1 below:

Scheme 1
In an embodiment, the method of synthesis of TAP-NEILOP_MW comprises following steps:
a) Mixing 2,6-pyridinedicarboxaldehyde and 2,4,6-triaminopyrimidine in a solvent in a microwave vial;
b) Dissolving the reaction mixture completely under sonication;
c) Sealing the microwave vial and placing it in a microwave reactor at 80±2 °C for 60 minutes under microwave irradiation power of 80 W;
d) Filtering the resulting precipitate;
e) Washing the obtained precipitate with excess of acetone; and
f) Drying the obtained product under vacuum at 80 °C for 2h.

In an embodiment, the solvent used in the method of synthesis of TAP-NEILOP_MW is N,N-Dimethylformamide (DMF).

In yet another embodiment, the imine linked polymer is synthesized using environmentally friendly method with faster reaction rates and high yield.

In an embodiment, the organic polymer has ample p-electron rich arenes and nitrogen centres which facilitates efficient interaction with iodine. The imine linked polymer is useful in nuclear waste management, environment remediation. Also, it has further applications in wastewater contamination of heavy metal, synthetic organic dyes and carbon sequestration because of the nitrogen enriched sites.

Even though we have explained the invention of the present disclosure using specific examples, this explanation is not meant to limit how you understand it. People who are skilled in this field may think of various changes and different versions of the invention after reading this description. We expect that such changes can be made without straying from the main idea or purpose of the invention as defined in the claims.

The present disclosure is further described with reference to the following examples, which are only illustrative in nature and should not be construed to limit the scope of the present disclosure in any manner.

EXAMPLES
Materials: 2,4,6-triaminopyrimidine (97%) and 2,6-pyridinedicarboxaldehyde (97%) were purchased from Sigma Aldrich. All chemicals were used as received without any further purification or modification.
Example1: Microwave assisted synthesis of TAP-NEILOP_MW:
2,6-pyridinedicarboxaldehyde (3 mmol, 0.405 g) and 2,4,6-triaminopyrimidine (2 mmol, 0.250 g) were mixed in DMF in a 10 mL microwave vial. The reaction mixture was completely dissolved under sonication. The microwave vial was sealed and placed in a CEM Discover microwave reactor at 80 °C for 60 minutes under microwave irradiation power of 80 W. The resulting polymer precipitate was recovered by filtration and washed extensively with excess of acetone. The sample was dried under vacuum at 80 °C for 2h. The yield of the polymer was found to be 72%. The schematic synthesis route of TAP-NEILOP_MW is represented in scheme 2 as shown in Figure 3.

Example 2: Characterization of TAP-NEILOP_MW:
The successful synthesis of TAP-NEILOP_MW was examined through FTIR spectroscopy. The FTIR spectra of the monomers and TAP-NEILOP_MW are shown in Figure 1a. The disappearance of characteristic primary amine bands of 2,4,6-triaminopyrimidine in the range of 3300-3500 cm-1 indicates the successful polymerization. The bands due to aldehyde C=O at 1710 cm-1 gets almost disappeared in the FTIR spectrum of TAP-NEILOP_MW. Additionally, the stretching and bending vibrations of C-H aldehyde functionality at 2860 and ~ 1349 cm-1, respectively of 2,6-pyridinedicarboxaldehyde gets completely disappeared as one can see in the FTIR spectrum of TAP-NEILOP_MW, which further confirms the polymerization of the monomers. Moreover, The clear change in the shapes of the bands in the range of 1350 cm-1 to 1650 cm-1, which is typically associated to C=N functionality, can be seen in the spectrum of polymer, which supports the imine linkage in the structure of TAP-NEILOP_MW as shown in Scheme 1. Powder X-Ray Diffraction (PXRD) examination was carried out to check the crystalline nature of TAP-NEILOP_MW. The lack of sharp peaks in the PXRD pattern shown in Figure 1b indicates the amorphous nature of the TAP-NEILOP_MW.
The prepared TAP-NEILOP_MW is insoluble in common organic solvents, implying its high physicochemical stability.

Example 3: Thermogravimetric analysis of TAP-NEILOP_MW:
Thermal stability of TAP-NEILOP_MW was investigated by TGA, which was performed in the temperature range of 30 °C to 700 °C in N2 atmosphere. The material was found thermally stable up to ~ 400 °C, as can be seen in Figure 2. The mass % loss occurs in three steps. The initial ~10% mass loss up to 125 °C could be attributed to the removal of trapped moisture and solvents from the polymeric framework. The second mass loss of ~ 11.3% in the temperature range of 100 ° to 400 °C could be attributed to the collapse of polymeric framework. After 400 °C the gradual mass loss can be seen which could be attributed to the carbonization of the material.

Example 4: Microstructural and morphological investigation of TAP-NEILOP_MW:
The microstructural and morphological investigation of TAP-NEILOP_MW was also carried out using FESEM analysis. The FESEM image of the material as shown in (Figure 4a) indicates the presence of agglomerated spherical nanoparticles. Moreover, Energy Dispersive X-ray spectroscopy (EDX) analysis of the materials was carried out to find out the elemental composition of the material. The polymer was found rich in Nitrogen as one can see the EDX spectrum of the selected area of the material showing in FESEM image (Figure 4).

Advantages of the microwave assisted synthesis of compound TAP-NEILOP_MW:
• This synthesis offers faster reaction rates with high yield.
• Avoids the use of toxic chemicals and metal catalysts.
• This method often incorporates safety features and offer automated control, making it a safer and more convenient alternative to conventional methods.
• Reducing reaction time, solvent waste and other side products.
• Offers higher yield in comparison to conventional methods.
• The current work is in agreement with UN Sustainable Development Goals 6 of (Clean Water and Sanitation), goal 7 of (Affordable and Clean Energy), and goal 13 of (Responsible Consumption and Production).

The inventors have developed the invention, so that advantage can be achieved in an economical, practical, and facile manner. While preferred aspects and example configurations have been shown and described, it is to be understood that various further modifications and additional configurations will be apparent to those skilled in the art. It is intended that the specific embodiments and configurations herein disclosed are illustrative of the preferred nature of the invention and should not be interpreted as limitations on the scope of the invention.
, Claims:We claim
1. A microwave assisted method for synthesizing nitrogen enriched triaminopyrimidine based imine linked organic polymer for use in safe and long-term radioactive iodine sequestration, comprising steps:
a) Mixing 2,6-pyridinedicarboxaldehyde (3 mmol, 0.405 g) and 2,4,6-triaminopyrimidine (2 mmol, 0.250 g) in a solvent in a microwave vial;
b) Dissolving the reaction mixture completely under sonication;
c) Sealing the microwave vial and placing it in a microwave reactor at 80 °C for 60 minutes under microwave irradiation power of 80 W;
d) Filtering the resulting precipitate;
e) Washing the obtained precipitate with excess of acetone; and
f) Drying the obtained product under vacuum at 80 °C for 2h.

2. The method as claimed in claim 1, wherein the solvent is DMF.

3. The method as claimed in claim 1, wherein the obtained yield of the organic polymer is 72%.

4. The method as claimed in claim 1, wherein the synthesis results in no or minimal side products.

5. The method as claimed in claim 1, wherein the organic polymer is characterized by thermogravimetric analysis indicating thermal stability up to 400°C.

6. The method as claimed in claim 1, wherein the organic polymer has wide applications in nuclear waste management, environmental remediation, iodine sequestration and carbon sequestration.

7. The method as claimed in claim 1, wherein the organic polymer has ample p-electron rich arenes and nitrogen centres which facilitates efficient interaction with iodine.