Rates of cleavage by aqueous methanolic perchloric acid have been measured for 4-(trimethylsilyl)diphenylmethane, 2-, 3-, and 9-(trimethylsilyl)phenanthrene, 2-(trimethylsilyl)-9,10-dihydrophenanthrene, and 1-(trimethylsilyl)pyrene. The values of the rates, krel, relative to those for trimethylsilylbenzene at 50δ are 7.9, 1.76, 2.1, 4.5, 12.8, and 223, respectively. In a plot of log krel against logf
Reactivity of pyrene dianion and some of its 2-substituted derivatives
作者:L. Rodenburg、R. de Block、T. W. N. Bieze、J. Cornelisse、J. Lugtenburg
DOI:10.1002/recl.19881070103
日期:——
A simple technique for the preparation of anions of polycyclic aromatic hydrocarbons is described. 1H and 13C NMRspectra of dianions of pyrene and derivatives of pyrene are reported and discussed. The electron density is greatest at the carbonatoms in the perimeter of the dianions. The presence of an electron-donating substituent at position 2 causes an increase in the charge at positions 1 and 3
描述了一种制备多环芳烃阴离子的简单技术。报告并讨论了的二价阴离子和derivatives的衍生物的1 H和13 C NMR谱。电子密度在二价阴离子周围的碳原子处最大。在位置2上存在供电子性取代基,导致位置1和3上电荷增加。
Fluorescence Enhancement of Pyrene Chromophores Induced by Alkyl Groups through σ–π Conjugation: Systematic Synthesis of Primary, Secondary, and Tertiary Alkylated Pyrenes at the 1, 3, 6, and 8 Positions and Their Photophysical Properties
We have systematically synthesized 1-, 3-, 6-, and 8-alkyl-substituted pyrene derivatives using the latest synthesis methods and investigated the effects of alkyl substitution on the photophysical properties of the pyrene chromophore. Like the trimethylsilyl group, which is known to enhance the fluorescence properties of some chromophores through sigma*-pi* conjugation, alkyl groups (primary, secondary, and tertiary) enhanced the fluorescence quantum yield of the pyrene chromophore through sigma-pi conjugation in most cases. While these enhancements in the fluorescence quantum yield were beyond expectations, the results were supported by absolute measurements. These results also indicate that ubiquitous alkyl groups can be used to tune the photophysical properties of the pyrene chromophore, as well as to improve the solubility or prevent aggregation. In other words, they can be used to develop new photofunctional materials.
Declercq; Delbeke; De Schryver, Journal of the American Chemical Society, 1993, vol. 115, # 13, p. 5702 - 5708