02590nas a2200205   4500008004100000022001400041245011100055210006900166260000900235300001400244490000700258520185700265100002402122700002502146700001902171700001702190700002402207700002402231856012902255       2022                        eng d  a1528-748300aPolymorphs of green fluorescence protein chromophore analogue: fluorescence switching with thermal stimuli0 aPolymorphs of green fluorescence protein chromophore analogue fl  cMAR   a1892-19050 v223 a<p>
	Polymorphs of fluorescent organic materials offer significant implications in optoelectronics and advanced materials as they modulate photoluminescence properties. A slight alteration in the conformation/packing of molecules in the crystals shows variation in photoluminescence. This necessitates the polymorph screening of these materials to develop novel crystalline forms with distinct fluorescence emissions for broader application. In continuation of our work on the polymorph screening of Green Fluorescence Protein Chromophore (GFPc), we have synthesized a new imidazoline derivative, ethyl (Z)-2-(2-methyl-5-oxo-4-(3,4,5-trimethoxybenzylidene)-4,5-dihydro-1H-imi dazol-1- yl)acetate (1). Polymorph screening of 1 under different crystallization conditions revealed three polymorphs, Form I (needle), Form II (block), and Form III (polycrystalline material). Forms I and II are the outcome of solution crystallization, whereas Form III was produced from the melt crystallization of Forms I and II. DSC, HSM, and powder and single-crystal XRD studies indicate the conversion of Form I and Form III crystals to Form II crystals on thermal stimuli. The photoluminescence studies revealed cyan, yellow, and yellowish-green fluorescence emission for Forms I, II, and III crystals, respectively. The difference in photoluminescence could be due to the variance in aggregation modes like H-aggregation in Form I and J-aggregation in Form II crystals. Form I, Form II, and Form III crystals also showed irreversible thermal fluorescent switching from cyan-yellow-green due to polymorphic phase transitions. The study correlates the direct observation of the modulation of the excited-state transition under thermal stimuli in the crystalline phase. It will help augment the pace in the research of thermally responsive fluorescent materials.</p>
1 aMali, Bhupendra, P.1 aDash, Soumya, Ranjan1 aBiswas, Anupam1 aVanka, Kumar1 aManoj, Kochunnoonny1 aGonnade, Rajesh, G.  uhttps://library.ncl.res.in/content/polymorphs-green-fluorescence-protein-chromophore-analogue-fluorescence-switching-thermal