Department of Chemistry, Annamalai University, Annamalainagar, 608 002, Tamilnadu, India.
J Fluoresc. 2012 Jan;22(1):269-79. doi: 10.1007/s10895-011-0957-5. Epub 2011 Aug 26.
H and (13)C NMR spectra were recorded for some novel picrate derivatives derived from 3,3-dimethyl-2,6-diarylpiperidin-4-ones and 3-benzyl-2,6-diarylpiperidin-4-one. The photophysical properties of the picrate derivatives were studied in several solvents, which include a wide range of apolar, polar and protic media. The observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed due to the presence of increased electrostatic interaction between N-protonated piperidone ring and picryl anion ring so that the picryl anion ring lies perpendicular to the plane of the N-protonated piperidone ring i.e., non co-planarity. Such a geometrical change in the excited state leads to an important Stokes shift, reducing the reabsorption and reemission effects in the detected emission in highly concentrated solutions. The higher fluorescence quantum yield of the picrate derivatives are observed in polar media.
对一些新型苦味酸盐衍生物进行了 1H 和 13C NMR 谱记录，这些衍生物是由 3,3-二甲基-2,6-二芳基哌啶-4-酮和 3-苄基-2,6-二芳基哌啶-4-酮衍生而来。在多种溶剂中研究了苦味酸盐衍生物的光物理性质，这些溶剂包括广泛的非极性、极性和质子性介质。观察到的较低荧光量子产率可能是由于非辐射去活速率常数的增加。这归因于 N-质子化哌啶酮环和苦味酸阴离子环之间存在增加的静电相互作用，使得苦味酸阴离子环垂直于 N-质子化哌啶酮环的平面，即非共面性。这种激发态的几何变化导致重要的斯托克斯位移，减少了在高浓度溶液中检测到的发射中的再吸收和再发射效应。在极性介质中观察到苦味酸盐衍生物的荧光量子产率较高。
