Photoactivation of Distal Groups in Polyfunctional Molecules

多官能分子远端基团的光活化

• 批准号: 8700333
• 负责人: Harry Morrison
• 金额: $ 22.35万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-04-15 至 1991-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8700333&HistoricalAwards=false
• 关键词: Photoactivation; Distal; Groups; Polyfunctional; Molecules

This grant in the Organic and Macromolecular Chemistry Program supports research on the mechanisms of light-induced chemical reactions. Dr. Morrison's focus in photochemical reactions is the interaction of close, but formally non-conjugated functional groups which interact in the excited states generated by light absorption. Such systems are important as models for many of the light-induced chemical sequences of life processes. In photosynthesis, for example, one "antenna" group in chlorophyll harvests light energy and then transfers it to a nearby "receptor" for initiating chemical changes. Photochemical reactions of bifunctional molecules can be broadly subclassified into those (a) involving bond formation between the two functionalities, and (b) those primarily involving only one of the two groups, the non-reacting moiety then serving as an "antenna" to harvest photons. In the latter case, a variety of mechanisms are now recognized which can lead to activation of the distal, reacting group. The reacting group may either be relatively transparent in the ultraviolet spectrum (examples are chlorine, carbethoxy, and alkene substituents), or be itself capable of asborption (a ketone, for example), but still potentially selectively activated by the atenna. This research is primarily addressed to "Class b" systems. The basic questions for which answers are sought include: (1) How general, and with what stereoelectronic limitations, are the various mechanisms for activiting distal functionalities; (2) How may these phenomena be utilized synthetically; and (3) How are they reflected in the photostability of complex molecules? As an out growth of research previously supported by Foundation Grant CHE-8318825, Dr. Morrison has also initiated studies involving metal ion catalysis in photochemistry and photochemistry in the gas phase. Both projects have uncovered new and intriguing chemistry, the extensions of which are included in the present program.

有机和高分子化学项目的这笔资助支持光诱导化学反应机制的研究。 莫里森博士研究光化学反应的重点是紧密但形式上非共轭的官能团之间的相互作用，这些官能团在光吸收产生的激发态下相互作用。 这些系统作为许多光诱导的生命过程化学序列的模型非常重要。 例如，在光合作用中，叶绿素中的一个“天线”基团收集光能，然后将其转移到附近的“受体”以引发化学变化。 双功能分子的光化学反应可大致细分为（a）涉及两个功能之间形成键的反应，以及（b）主要仅涉及两个基团之一的反应，非反应部分则充当收集光子的“天线”。 在后一种情况下，现在已经认识到多种机制可以导致远端反应基团的激活。 反应基团可以在紫外光谱中相对透明（例如氯、乙酯基和烯烃取代基），或者本身能够吸收（例如酮），但仍然可能被天线选择性激活。 这项研究主要针对“B 类”系统。 寻求答案的基本问题包括：（1）激活远端功能的各种机制有多普遍，以及有哪些立体电子学限制； (2)如何综合利用这些现象； (3)它们如何反映在复杂分子的光稳定性中？ 作为先前由基金会资助 CHE-8318825 支持的研究的延伸，Morrison 博士还启动了涉及光化学中的金属离子催化和气相光化学的研究。 这两个项目都发现了新的、有趣的化学，其扩展包含在当前的计划中。