<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Zaware, Santosh B.</style></author><author><style face="normal" font="default" size="100%">Dagade-Waghmode, Shobha</style></author><author><style face="normal" font="default" size="100%">Gonnade, Rajesh G.</style></author><author><style face="normal" font="default" size="100%">Srinivas, Darbha</style></author><author><style face="normal" font="default" size="100%">Rane, Sandhya Y.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Magnetic phase transition in valence tautomers as polymorphs of 3-iodolawsone: Single crystal X-ray structure, DSC and EPR studies</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Molecular Structure</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">3-Iodolawsone</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydroxynaphthoquinone (HNQ)</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydroxynaphthosemiquinone radical (HNSQ)</style></keyword><keyword><style  face="normal" font="default" size="100%">Magnetic phase transition</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymorphs</style></keyword><keyword><style  face="normal" font="default" size="100%">Valence tautomers</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year><pub-dates><date><style  face="normal" font="default" size="100%">DEC</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">1-3</style></number><publisher><style face="normal" font="default" size="100%">ELSEVIER SCIENCE BV</style></publisher><pub-location><style face="normal" font="default" size="100%">PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS</style></pub-location><volume><style face="normal" font="default" size="100%">938</style></volume><pages><style face="normal" font="default" size="100%">328-335</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Three polymorphs of 3-iodolawsone (I-III) have been isolated and characterized by single crystal X-ray diffraction, electron paramagnetic resonance (EPR) spectroscopy and differential scanning calorimetry (DSC) techniques. Polymorphs I and II were crystallized from methanol in two different valence tautomeric forms: hydroxynaphthoquinone (HNQ) and hydroxynaphthoseimquinone (HNSQ) as needles and thick plates, respectively. Polymorph III was crystallized from ethanol in HNQ form, as thin plates Chiral crystals of I belongs to the orthorhombic P2(1)2(1)2(1) space group: II and III belong to the monochnic non-centrosymmetric space group Cc. The molecules are packed via O-H O bonding and pi . pi stacking interactions. The study reveals that relatively stronger intermolecular H-bonding (2.02 angstrom) and most favoured pi . pi stacking (similar to 3 49 angstrom) interactions lead II to HNSQ radicals, presence of which was confirmed by EPR (g = 2.0052) spectroscopy. Interestingly, these materials exhibit crystal-to-crystal magnetic phase transition from polymorph I (diamagnetic) to polymorph II (paramagnetic structure) at 171.1 degrees C as identified by DSC and X-ray crystallographic studies (C) 2009 Elsevier B.V. All rights reserved&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">1-3</style></issue><custom3><style face="normal" font="default" size="100%">Foreign</style></custom3><custom4><style face="normal" font="default" size="100%">1.599</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Mali, Bhupendra P.</style></author><author><style face="normal" font="default" size="100%">Dash, Soumya Ranjan</style></author><author><style face="normal" font="default" size="100%">Nikam, Shrikant B.</style></author><author><style face="normal" font="default" size="100%">Puthuvakkal, Anisha</style></author><author><style face="normal" font="default" size="100%">Vanka, Kumar</style></author><author><style face="normal" font="default" size="100%">Manoj, Kochunnoonny</style></author><author><style face="normal" font="default" size="100%">Gonnade, Rajesh G.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Five concomitant polymorphs of a green fluorescent protein chromophore (GFPc) analogue: understanding variations in photoluminescence with pi-stacking interactions</style></title><secondary-title><style face="normal" font="default" size="100%">Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">green fluorescent protein</style></keyword><keyword><style  face="normal" font="default" size="100%">hydrogen bonds</style></keyword><keyword><style  face="normal" font="default" size="100%">isostructurality</style></keyword><keyword><style  face="normal" font="default" size="100%">photoluminescence</style></keyword><keyword><style  face="normal" font="default" size="100%">pi-stacking</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymorphs</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2020</style></year><pub-dates><date><style  face="normal" font="default" size="100%">OCT</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">76</style></volume><pages><style face="normal" font="default" size="100%">850-864</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;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.&lt;/p&gt;
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