@article {46689,
	title = {Five concomitant polymorphs of a green fluorescent protein chromophore (GFPc) analogue: understanding variations in photoluminescence with pi-stacking interactions},
	journal = {Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials},
	volume = {76},
	year = {2020},
	month = {OCT},
	pages = {850-864},
	type = {Article},
	abstract = {<p>The synthetically modified green fluorescent protein chromophore analogue 3,4,5-trimethoxybenzylidene imidazolinone (1) yielded five polymorphs (I, II, III, IV, V) concomitantly irrespective of the solvent used for crystallization. The pentamorphic modification of 1 is solely due to the interplay of iso-energetic weak intermolecular interactions in molecular associations as well as the conformational flexibility offered by a C-C single bond, which connects the electron-deficient moiety imidazolinone with the electron-rich trimethoxybenzylidene group. A common structural feature observed in all the polymorphs is the formation of a {\textquoteleft}zero-dimensional{\textquoteright} centrosymmetric dimeric unit through a short and linear C-H center dot center dot center dot O hydrogen bond engaging phenyl C-H and imidazolinone carbonyl oxygen. However, the networking of these dimeric units showed a subtle difference in all the polymorphs. The 2D isostructurality was observed between polymorphs I, II and III, while the other two polymorphs IV and V revealed only {\textquoteleft}zero-dimensional{\textquoteright} isostructurality. The different fluorescence emissions of Form I (blue) and Forms II to V (yellow) were attributed to the differences in pi-stacking interactions. It shows that one can modulate the photophysical properties of these smart materials by slightly altering their crystal structure. Such an approach will aid in developing new multi-colour organic fluorescent materials of varying crystal structures for live-cell imaging and fluorescent sensing applications.</p>
},
	keywords = {green fluorescent protein, hydrogen bonds, isostructurality, photoluminescence, pi-stacking, Polymorphs},
	doi = {10.1107/S2052520620010343},
	author = {Mali, Bhupendra P. and Dash, Soumya Ranjan and Nikam, Shrikant B. and Puthuvakkal, Anisha and Vanka, Kumar and Manoj, Kochunnoonny and Gonnade, Rajesh G.}
}
