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Mechanically adaptable molecular crystals have potential applications in flexible smart materials and devices. Here, we report the mechanism of plastic deformation in single crystals of a small organic molecule (N-(4-ethynylphenyl)-3-fluoro-4-(trifluoromethyl)benzamide) that can be repeatedly irreversibly bent and returned to its original shape without concomitant delamination or loss of integrity. Along with the quantification of the crystals' local and bulk mechanical properties (hardness, indentation modulus and Young's modulus), micro-focus synchrotron X-ray diffraction mapping show that upon deformation, molecular layers lined with trifluoromethyl groups cooperatively slip past one another resulting in their impressive plastic malleability.

info:eu-repo/semantics/published

Katharigatta N Venugopala,1,2 G B Dharma Rao,3 Subhrajyoti Bhandary,3 Melendhran Pillay,4 Deepak Chopra,3 Bandar E Aldhubiab,1 Mahesh Attimarad,1 Osama Ibrahim Alwassil,1 Sree Harsha,1 Koleka Mlisana4 1Department of Pharmaceutical Sciences, College of Clinical Pharmacy, King Faisal University, Al-Ahsa, Kingdom of Saudi Arabia; 2Department of Biotechnology and Food Technology, Durban University of Technology, Durban, South Africa; 3Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, India; 4Department of Microbiology, National Health Laboratory Services, KZN Academic Complex, Inkosi Albert Luthuli Central Hospital, Durban, South Africa Abstract: The novel (1-(4-aryl)-1H-1,2,3-triazol-4-yl)methyl, substituted phenyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate derivatives were synthesized by the click reaction of the dihydropyrimidinones, bearing a terminal alkynyl group, with various substituted aryl azides at room temperature using a catalytic amount of Cu(OAc)2 and sodium ascorbate in a 1:2 ratio of acetone and water as a solvent. The newly synthesized compounds were characterized by a number of spectroscopic techniques, such as infrared, liquid chromatography-mass spectrometry, 1H, and 13C nuclear magnetic resonance along with single crystal X-ray diffraction. The current procedure for the synthesis of 1,2,3-triazole hybrids with dihydropyrimidinones is appropriate for the synthesis of a library of analogs 7a-l and the method accessible here is operationally simple and has excellent yields. The title compounds 7a-l were evaluated for their in vitro antitubercular activity against H37RV and multidrug-resistant strains of Mycobacterium tuberculosis by resazurin microplate assay plate method and it was found that compound 7d was promising against H37RV and multidrug-resistant strains of M. tuberculosis at 10 and 15 µg/mL, respectively. Keywords: 1,2,3-triazole, dihydropyrimidinone, click chemistry, antitu