Agnihotri Harsha, Vasu Anuji K, Palakollu Veerabhadraiah, Kanvah Sriram
Department of Chemistry, Indian Institute of Technology Gandhinagar, Chandkheda, Ahmedabad 382 424, India.
Photochem Photobiol Sci. 2015 Dec;14(12):2159-67. doi: 10.1039/c5pp00179j.
Neutral and cationic diarylbutadienes with pyridine and pyridinium groups as electron acceptors with dimethylamine and diphenylamine as electron donors were synthesized. The absorption and emission properties of these dienes were investigated in homogeneous organic solvents and in sodium cholate media. In strongly polar solvents, both neutral and cationic fluorophores exhibit a bathochromic shift of emission characteristics of intramolecular charge transfer (ICT) excited states. The presence of a strongly electron withdrawing pyridinium group induces large absorption (∼480 nm) and emission wavelength shifts (near ∼680 nm) in polar solvents. This solvatochromic behavior is utilized as a tool to examine the fluorophore-sodium cholate interaction. Significant hypsochromic emission shifts (up to ∼66 nm) and concomitant intensity enhancement (up to 32-fold) are seen for these fluorophores in the presence of increasing concentrations of sodium cholate. Fluorescence lifetime measurements reveal biexponential decay patterns indicating the binding of molecules in distinct cholate environments.
合成了以吡啶和吡啶鎓基团作为电子受体、二甲胺和二苯胺作为电子供体的中性和阳离子型二芳基丁二烯。研究了这些二烯在均相有机溶剂和胆酸钠介质中的吸收和发射特性。在强极性溶剂中，中性和阳离子型荧光团均表现出分子内电荷转移（ICT）激发态发射特性的红移。强吸电子吡啶鎓基团的存在导致在极性溶剂中出现较大的吸收（约480 nm）和发射波长位移（接近约680 nm）。这种溶剂化显色行为被用作研究荧光团与胆酸钠相互作用的工具。在胆酸钠浓度增加时，这些荧光团出现了显著的蓝移发射位移（高达约66 nm）和伴随的强度增强（高达32倍）。荧光寿命测量揭示了双指数衰减模式，表明分子在不同胆酸盐环境中的结合。
