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Molecular Information and Crystal Control in Solid State Photochemistry. Radical Pair Dynamics, Synthetic Applications and Triplet Quantum Chains

固态光化学中的分子信息和晶体控制。

基本信息

批准号：
1855342
负责人：
Miguel Garcia-Garibay
金额：
$ 56万
依托单位：
University of California-Los Angeles
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-01 至 2022-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1855342&HistoricalAwards=false
关键词：
Molecular Information Crystal Control Solid

项目摘要

One of the most interesting and promising frontiers in the chemical sciences involves the use of crystalline solids exposed to light for the purpose of carrying out special chemical transformations. Reactions in crystals differ from processes in liquids and in gases because molecules in the crystalline state are held rigidly and orderly, such that they all have the same fate when a reaction occurs. With support from the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Miguel A. Garcia-Garibay of the Department of Chemistry and Biochemistry at The University of California, Los Angeles, uses crystals to explore two types of unusual but promising chemical reactions. One reaction examines the effect of magnetic fields. Magnetic fields play a role in the navigation systems of migrating birds and have the potential to control some types of chemical systems. The second reaction, known as a quantum chain reaction, is process where a single light particle, or photon, leads to many chemical events (an amplification process). Quantum chain reactions in crystals are enabled by strong interactions between neighboring molecules. This interaction transforms photons into moveable "excitons", facilitated by chemical reactions that retain and unleash large amounts of energy. A third objective of this grant is to demonstrate the advantages of reactions in crystals for the conversion of simple chemicals into high value substances. This multifaceted project provides an excellent multi-disciplinary training ground for students in quantum information systems (QIS). It helps develop the intellectual and human infrastructure needed to support our country's academic and industrial enterprises related to quantum computing, quantum biology, and sensing. The connection between biological systems and molecules in crystals provides Professor Garcia-Garibay with an opportunity to develop a freshman-level course on the role of light in the origins of life. This course develops multimedia teaching and demonstration aids that are shared with the general public.Over the last few years the Garcia-Garibay group has established the structural requirements needed to engineer reactions in crystalline solids. This project addresses three aspects of chemical dynamics that have not been accessible by studying reactions in liquid solutions or in the gas phase. First, by taking advantage of crystalline ketones which have radical stabilizing substituents at the two alpha-carbons, the researchers are able to generate triplet radical pairs under conditions not available previously. With strongly interacting spins, these radical pairs have a relatively large Singlet-Triplet energy gap. When combined with the use of nanocrystalline suspensions as a medium to carry out laser flash photolysis (pump-probe) experiments, this project provides a unique opportunity to measure the dynamics of intersystem crossing in the solid state. Structural modifications of the starting ketone measured by single crystal X-ray diffraction and solid state nuclear magnetic resonance provide opportunities to analyze the kinetics of the triplet excited states and sequential radical pair intermediates. The interplay of spin dynamics and chemical dynamics is probed by measuring the kinetics of intersystem crossing as a function of external magnetic fields and magnetic isotope effects. Other aspects of solid state photochemical reactivity that are encompassed by this project include the total synthesis of the natural product Chimonanthin using solid state photodecarbonylation as the key step. The triplet exciton-enabled quantum chain reaction of crystalline Dewar benzenes is also explored. This chain process is expected to give a large number of product molecules per photon absorbed. Altogether, the research activities in this project improve the fundamental understanding of reaction mechanisms and chemical reactivity in rigid materials and provide students with an opportunity to receive a highly interdisciplinary training.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

化学科学中最有趣和最有前途的前沿领域之一涉及使用暴露于光的结晶固体进行特殊的化学转化。晶体中的反应不同于液体和气体中的过程，因为处于结晶状态的分子被严格有序地保持，因此当反应发生时，它们都有相同的命运。在化学系化学结构、动力学机制B项目的支持下，Miguel A.加州大学洛杉矶分校化学与生物化学系的加西亚-加里贝（Garcia-Garibay）使用晶体探索两种不寻常但有前途的化学反应。一种反应是检验磁场的影响。磁场在候鸟的导航系统中发挥作用，并有可能控制某些类型的化学系统。第二个反应，被称为量子链式反应，是一个单一的光粒子或光子，导致许多化学事件（放大过程）的过程。晶体中的量子链式反应是由相邻分子之间的强相互作用实现的。这种相互作用将光子转化为可移动的“激子”，通过保留和释放大量能量的化学反应促进。这项资助的第三个目标是证明晶体中的反应将简单化学物质转化为高价值物质的优势。这个多方面的项目为量子信息系统（QIS）的学生提供了一个很好的多学科培训基地。它有助于发展支持我国与量子计算、量子生物学和传感相关的学术和工业企业所需的智力和人力基础设施。生物系统和晶体中分子之间的联系为Garcia-Garibay教授提供了一个机会，可以开发一门关于光在生命起源中的作用的新生课程。本课程开发了多媒体教学和演示辅助工具，与公众共享。在过去的几年里，Garcia-Garibay小组已经建立了晶体固体中工程反应所需的结构要求。该项目涉及化学动力学的三个方面，这些方面无法通过研究液体溶液或气相中的反应来获得。首先，通过利用在两个α-碳上具有自由基稳定取代基的结晶酮，研究人员能够在以前不可用的条件下产生三重态自由基对。在强相互作用的自旋下，这些自由基对具有相对较大的单重态-三重态能隙。当结合使用纳米晶体悬浮液作为介质进行激光闪光光解（泵浦-探测）实验，该项目提供了一个独特的机会来测量在固态系统间交叉的动态。通过单晶X-射线衍射和固态核磁共振测量的起始酮的结构修饰提供了分析三重激发态和顺序自由基对中间体的动力学的机会。自旋动力学和化学动力学的相互作用，探讨通过测量动力学的系间交叉作为外部磁场和磁性同位素效应的函数。该项目所涵盖的固态光化学反应的其他方面包括使用固态光脱羰基作为关键步骤的天然产物Chimonanthin的全合成。三重态激子使能的量子链反应的结晶杜瓦苯进行了探索。这种链式过程预计每个吸收的光子会产生大量的产物分子。总的来说，该项目的研究活动提高了对刚性材料的反应机理和化学反应性的基本理解，并为学生提供了接受高度跨学科培训的机会。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（9）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Scalable Synthesis of Vicinal Quaternary Stereocenters via the Solid-State Photodecarbonylation of a Crystalline Hexasubstituted Ketone

DOI：
10.1021/acs.orglett.0c03226
发表时间：
2020-11-20
期刊：
ORGANIC LETTERS
影响因子：
5.2
作者：
Chang, Trevor Y.;Dotson, Jordan J.;Garcia-Garibay, Miguel A.
通讯作者：
Garcia-Garibay, Miguel A.

Mechanistic Studies of Adamantylacetophenones with Competing Reaction Pathways in Solution and in the Crystalline Solid State

DOI：
10.1021/acs.joc.9b01720
发表时间：
2019-09-06
期刊：
JOURNAL OF ORGANIC CHEMISTRY
影响因子：
3.6
作者：
Hipwell, Vince M.;Garcia-Garibay, Miguel A.
通讯作者：
Garcia-Garibay, Miguel A.

A Green Chemistry Approach toward the Stereospecific Synthesis of Densely Functionalized Cyclopropanes via the Solid-State Photodenitrogenation of Crystalline 1-Pyrazolines

通过结晶 1-吡唑啉的固态光脱氮立体定向合成致密功能化环丙烷的绿色化学方法

DOI：
10.1021/acs.joc.1c01808
发表时间：
2022
期刊：
The Journal of Organic Chemistry
影响因子：
0
作者：
Chang, Trevor Y.;Adrion, Daniel M.;Meyer, Alana Rose;Lopez, Steven A.;Garcia-Garibay, Miguel A.
通讯作者：
Garcia-Garibay, Miguel A.

Evaluation of the photodecarbonylation of crystalline ketones for the installation of reverse prenyl groups on the pyrrolidinoindoline scaffold