New Nonlinear Optical, Piezoelectric, Pyroelectric Materials Based on L-Nitroarginine

Project Status: 3 Proposal review
Commencement Date: 18.09.2022
Duration in months: 36 months

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Participating Institutions



National Academy of Sciences of the Republic of Armenia / Scientific-Technological Center of Organic and Pharmaceutical Chemistry, National Academy of Sciences, Republic of Armenia (STCOPHCH)


The aim of the Project is the preparation and systematic research of new crystalline materials with nonlinear optical, piezoelectric and pyroelectric properties. During the previous years extensive search of nonlinear optical (NLO) materials, which may combine positive features of inorganic (good mechanical and thermal properties, possibility of large high quality crystal growth, transparency in the UV-Vis-NIR range, etc.) and organic molecular crystals (possibility of getting high NLO properties by means of wide variation of chemical composition, particularly, by selection of electron-donor and electron-acceptor groups), has been conducted. The discovery of promising properties of the crystal L-arginine phosphate monohydrate (L-Arg.H3PO4.H2O, LAP), which in particular has stimulated the search and study of other L-arginine salts, has been of great importance for the development of this direction.

The Project suggests a way of essential increase of NLO properties of L-arginine and salts on its basis by means of insertion in L-arginine molecule along with the existing electron-donor amino-group (NH2) also electron-acceptor nitro-group (NO2). It could seem to be a non-promising way as L-nitroarginine (L-NNA), known in the form of powder, as well as its known crystalline salt L-nitroarginine hydrochloride monohydrate (L-NNA.HCl.H2O), do not show noticeable NLO properties. However, we were able to develop a new crystalline form of L-nitroarginine (?-form), which shows high NLO properties, as well as to find out the reason of absence of high NLO properties of L-NNA.HCl.H2O. We found two crystalline forms of L-NNA.HBr.H2O (? and ?), ?-form of which is isostructural to L-NNA.HCl.H2O and does not show noticeable NLO properties, while ?-form shows high NLO properties. Therefore, the reason is not in the composition or molecular structure but in the unfavorable crystal packing. The analysis and comparison of the structures showed that L-NNA.HCl.H2O with the same symmetry, as compared to the ?-form of L-NNA.HBr.H2O, has got pseudocentrosymmetric structure, which is the reason of the absence of NLO properties. We have got other L-nitroarginine salts with promising properties as well. Thus, our preliminary study has allowed to find a new source of promising NLO materials. These materials may show piezoelectric and pyroelectric properties as well, and discovery of the L-Arg.2HBr.H2O crystal with high pyroelectric properties allows to hope that pyroelectric materials of practical importance may be found among new materials on the basis of L-nitroarginine as well. Based upon above-mentioned facts, we plan to conduct a more systematic and detailed research on preparation of new crystalline materials on the basis of L-nitroarginine. The developed materials will be identified and characterized by modern methods of IR, Raman, NMR spectroscopy and thermal analysis, and their crystal and molecular structures will also be determined. More promising NLO materials will be discovered by the widespread method of second harmonic generation (SHG) in the powder (Kurtz and Perry method) as well as by a more exact method of second harmonic of evanescent wave (SHEW) (Kiguchi method), thereafter, activities will be carried out on growing their single crystals from aqueous solution. Methods of modern quantum-chemical calculations will be used for calculating the frequency of vibrational spectra, simulation NMR spectra as well as NLO properties. The growth of single crystals of necessary sizes and acceptable quality will be used for measuring the set of linear and nonlinear optical as well as piezoelectric and pyroelectric properties. Conditions for growing single crystals will be optimized for the most promising materials, which may serve as the basis of the technology of their commercial production. R.A. Apreyan, H.A. Karapetyan, R.P. Sukiasyan, G.G. Martirosyan, T.K. Sargsyan, A.A. Bush, V.B. Gavalyan and other experienced and qualified physics and chemists are involved in the Project. Foreign collaborators from leading scientific centers of the US and Europe will have an active role in the solution of the significant problems of the Project.

Performance of the Project meets the Goals and Objectives of ISTC. Significant number of participants of the Project will have an opportunity to use their skills and experience in peace purposes before being involved in defensive subjects.

Performance of the Project will assist to expansion and deepening of the contacts of Armenian researches with scientists from leading scientific centers of the USA and EU in every possible way, and thus to be integrated into the international scientific community. The scientific direction "New materials" is one of five priority scientific directions approved by the Government of the Armenia. Therefore successful performance of the Project will assist the solution of one of the important national problems. Performance of the Project will support fundamental and applied researches in peace purposes and transition to the market economy.