作者:Jayaraman Jayabharathi、Venugopal Thanikachalam、Manoharan Padmavathy、Marimuthu Venkatesh Perumal
DOI:10.1007/s10895-011-0957-5
日期:2012.1
H and 13C 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.
研究人员记录了一些由 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-酮衍生的新型苦味酸盐衍生物的 H 和 13C NMR 光谱。研究人员在几种溶剂(包括各种非极性、极性和原生介质)中对皮酸盐衍生物的光物理特性进行了研究。观察到的较低荧光量子产率可能是由于非辐射失活速率常数的增加。这是因为 N-质子化哌啶酮环和吡啶基阴离子环之间的静电作用增强,从而使吡啶基阴离子环垂直于 N-质子化哌啶酮环的平面,即非共平面性。激发态的这种几何变化会导致重要的斯托克斯偏移,从而降低高浓度溶液中检测到的发射中的重吸收和再发射效应。在极性介质中可以观察到皮酸盐衍生物的荧光量子产率更高。