ELECTRON-TRANSFER MECHANISMS IN PHOTOCHEMICAL-TRANSFORMATIONS OF IMINIUM SALTS
ELECTRON-TRANSFER MECHANISMS IN PHOTOCHEMICAL-TRANSFORMATIONS OF IMINIUM SALTS
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DOI：
10.1021/ar00088a003
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发表时间：
1983-01-01
影响因子：
18.3
通讯作者：
MARIANO, PS
中科院分区：
文献类型：
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作者：
MARIANO, PS
有机光化学领域的研究集中在激发态化学的两个相互关联的方面。对电子物理现象的研究已经探索了激发态通过发射、无辐射衰变和能量转移而失活的机制。有机激发态的化学反应性是为了揭示新的反应过程，详细说明其机理，并阐明区域化学和立体化学中控制反应效率和选择性的因素。在许多情况下，所揭示的反应具有适当的特性，可用作合成方法。这些研究主要集中在经典的光化学反应中，如酮的氢原子夺取、烯烃的顺反异构化或环加成、共轭酮的重排、芳烃的光异构化和多烯的电环化等。近年来，人们对涉及激发态电子转移的光化学的一个新领域越来越感兴趣。在这一领域的探索性和机理研究已经发现了激发态淬灭，光敏化和反应引发的单电子转移（SET）或激发态的有机系统的新途径。许多由SET机制进行的光化学转化似乎特别适合于合成实践。本帐户的目的是简要概述SET在激发态化学中的一般特征，并回顾我们最近对含有亚胺阳离子基团的系统的光化学研究结果。[1]作为理解激发态SET基础的概念起源于激发态复合物形成的早期研究。在这个问题上积累的大量数据表明，各种各样的激发态过程是通过激发态分子与基态物种的相同（形成同源二聚体或准分子）或不同（形成异源二聚体或激基复合物）的碰撞形成的复合物的介入而发生的。2复合物相对于前体激发态的稳定性最初归因于激子共振相互作用，包括两个组分的激发离域。3.电荷转移是激发态复合物稳定化的另一个重要组成部分。[4]观测结果证实了这一假设，观测结果表明，帕特里克S. Mariano于1942年出生于新泽西州的Passaic。他在迪金森大学获得了化学学士学位，并获得了博士学位。来自威斯康星州的大学。在耶鲁大学进行了2年的博士后工作后，他于1970年加入德克萨斯农工大学，并于1979年转到马里兰州大学，目前担任化学教授。主要研究方向为新合成方法的开发和天然产物的合成。他是卡米尔和亨利德雷福斯教师学者奖，1975年至1980年。
Studies in the area of organic photochemistry have focused on two interrelated aspects of excited-state chemistry. Investigations of photophysical phenomena have probed the mechanisms for excited-state deacti-vation by emission, radiationless decay, and energy transfer. The chemical reactivity of organic excited states has been explored with the intent of uncovering new reaction processes, detailing their mechanisms and illucidating thefactors that controlreaction efficiencies and selectivities manifestedin regiochemistry and stereochemistry. In a number of cases, the reactions uncovered possess the proper characteristics to be ap-plicable as synthetic methods. These investigations have concentrated mainly on classical photochemical processes exemplified by ketone hydrogen atom ab-stractions, olefin cis-trans isomerizations or cyclo-additions, conjugated ketone rearrangements, arene photoisomerizations, and polyene electrocyclizations. In recent years interest has grown in a new area of photochemistry involving excited-state electron transfer. Exploratory and mechanisitic studies in this area have uncovered novel pathways for excited-state quenching, photosensitization, and reaction initiated by single electron transfer (SET) from or to excited states of organic systems. Many of the photochemical trans-formations proceeding by SET mechanisms appear to be particularly suited to synthetic practice. The aim of this Account is to briefly outline the general features of SET in excited-state chemistry and to review the results of our recent photochemical studies of systems containing the iminium cation grouping. 1 The concepts that serve as the foundation for an understanding of excited-state SET have their origins in early investigations of excited-state complex forma-tion. The body of data accumulated on this subject suggests that a wide variety of excited-state processes occur via the interventionof complexes formed by en-counter of excited-state molecules with ground-state species of the same (forming homodimers or excimers) or different (forming heterodimers or exciplexes) iden-tity. 2 The stabilities of the complexes relative to precursor excited states were initially attributed to exciton resonance interactions involving delocalization of excitation over both components. 3 It is now clear that charge transfer serves as another important com-ponent of excited-state complex stabilization. 4 This postulate is substantiated by observations that demonstrate that the wavelength maxima for emission from, Patrick S. Mariano was born in 1942 In Passaic, NJ. He received his BS in Chemistry at Falrlelgh Dickinson University and his Ph. D. from the Univer-sity of Wisconsin. Following 2 years of postdoctoral work at Yale University, he joined in 1970 the faculty at Texas A&M University, and in 1979 he moved to the University of Maryland, where he Is presently Professor of Chemistry. His research Interests are the development of new synthetic methodolgy and natural product synthesis. He was Camille and Henry Dreyfus Teacher-Scholar Awardee, 1975-1980.