Photoirradiation of perylene in the presence of 1,4-dicyanobenzene and NaCN in a benzonitrile (BN)/water emulsion under vigorous stirring gave 1- and 3-cyanoperylene in a total yield of 15%. For kinetic and mechanistic studies of the photoreaction, we conducted single-droplet measurements by using a laser trapping-microspectroscopy technique. Although determination of the incident light intensity absorbed by a solute in the emulsion is in general very difficult owing to strong light scattering, that in single laser-trapped BN droplets dispersed in water was successful on the basis of the photooxidation reaction of 9,10-disubstituted anthracene. The quantum yield of the photocyanation of perylene (ΦCN) was then determined to be 4.9 × 10−3. Furthermore, we found that ΦCN was linearly proportional to the inverse of the droplet radius: the reaction efficiency increased with decreasing droplet size through an increase in the surface area/volume (A/V) ratio of a droplet. This is the first demonstration of micrometre droplet size effects on the quantum yield for a photoreaction across the droplet/water interface.
在剧烈搅拌下,1,4-二
氰基苯和 NaCN 在苯腈(BN)/
水乳液中对过烯烃进行光照射,可得到 1-和 3-
氰基过炔,总产率为 15%。为了对光反应的动力学和机理进行研究,我们采用激光捕获-微光谱技术进行了单液滴测量。虽然由于强烈的光散射,测定乳液中溶质吸收的入射光强度通常非常困难,但根据 9,10-二取代
蒽的光氧化反应,成功测定了分散在
水中的单个激光捕获 BN 液滴的入射光强度。随后测定的过炔光
氰化量子产率(ΦCN)为 4.9 × 10-3。此外,我们还发现 ΦCN 与液滴半径的倒数成线性关系:液滴的表面积/体积(A/V)比增加,反应效率随液滴尺寸的减小而提高。这是首次证明微米级液滴大小对液滴/
水界面光反应量子产率的影响。