%0 Journal Article %J Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials %D 2020 %T Five concomitant polymorphs of a green fluorescent protein chromophore (GFPc) analogue: understanding variations in photoluminescence with pi-stacking interactions %A Mali, Bhupendra P. %A Dash, Soumya Ranjan %A Nikam, Shrikant B. %A Puthuvakkal, Anisha %A Vanka, Kumar %A Manoj, Kochunnoonny %A Gonnade, Rajesh G. %K green fluorescent protein %K hydrogen bonds %K isostructurality %K photoluminescence %K pi-stacking %K Polymorphs %X

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 `zero-dimensional' 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 `zero-dimensional' 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.

%B Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials %V 76 %P 850-864 %8 OCT %G eng %9 Article %3

Foreign

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2.048

%R 10.1107/S2052520620010343