Deactivation Behavior and Excited-State Properties of (Coumarin-4-yl)methyl Derivatives. 2. Photocleavage of Selected (Coumarin-4-yl)methyl-Caged Adenosine Cyclic 3‘,5‘-Monophosphates with Fluorescence Enhancement
作者:Torsten Eckardt、Volker Hagen、Björn Schade、Reinhardt Schmidt、Claude Schweitzer、Jürgen Bendig
DOI:10.1021/jo010692p
日期:2002.2.1
UV/vis spectroscopical properties (absorption and fluorescence) of 1-6 and 7-12 have been examined in methanol/aqueous HEPES buffer solution. Donor substitution in the 6-position causes a strong bathochromic shift of the long-wavelength absorption band, whereas substitution in the 7-position leads only to a weak red shift. The photochemical cleavage of the caged cAMPs was investigated, and the photoproducts
(香豆素-4-基)甲基笼罩的腺苷环3',5'-单磷酸酯(cAMPs)1-6的一系列轴向和赤道非对映异构体,在6-和/或-中具有甲氧基,二烷基氨基或无取代基已经合成了7位和它们相应的4-(羟甲基)香豆素光产物7-12。在甲醇/ HEPES缓冲溶液中检测了1-6和7-12的光化学和UV / vis光谱特性(吸收和荧光)。供体在6-位的取代引起长波长吸收带的强烈的红移,而在7-位的取代仅导致弱的红移。笼养的cAMPs的光化学裂解进行了调查,并分析了光产物。光化学量子产率,荧光量子产率,确定了激发单重态的寿命。使用中间形成的香豆基甲基阳离子的电子稳定作用,在香豆素部分的7位具有供体取代基的笼状cAMP中,获得了最高的光化学量子产率值(光S(N)1机理)。用6-位供体取代时,香豆素甲基阳离子的适度电子稳定作用被强的红移引起过度补偿,从而减小了激发态S(1)与相应香豆素甲基阳离子之间的能隙。cAMP的