基于Ir和Ni的金属光氧化还原催化反应机制的理论研究

The dual catalytic strategy for the combination of photocatalysts and transition metal catalysts can utilize effectively the abundant visible light resources to realize a variety of novel chemical bonds construction and functionalization, which provides a promising photochemical transformation platform with potential applications in the synthesis of fine chemicals and medical industry. The multi-configurational perturbation theory together with the kinetic assessment regarding the rate calculations of the single electron transfer (SET) will be employed to explore the key issues that control the efficiencies of metallaphotoredox catalytic coupling reactions of Iridium and Nickel complexes from the theoretical viewpoint. The following issues will be investigated in this proposal: (1) The structure-activity relationship will be established between the structural modifications and the absorption/emission spectra of different photocatalysts based on the accurate excited state calculations. Aforementioned computational efforts of photocatalysts, combined with the calculation of the redox potential of the excited state can be used to reveal the thermodynamic control factors to trigger SET events in photocatalytic reactions. (2) By calculating the minimum energy paths of several typical Iridium-Nickel metallaphotoredox catalytic C-C coupled alkylation reactions to establish a theoretical model describing the SETs among photocatalysts, transition metal catalysts and substrates, which aims to disclose the determinating factors for controlling the photocatalytic cycle. (3) Based on the thermodynamic stabilities and the couplings between initial and final states for excited state electron transfer, the SET rates can be calculated to evaluate kinetically the photocatalytic efficiency and to develop finally the universal regulation theory regarding the metallaphotoredox catalysis driven by excited state electron transfer.

可见光和过渡金属催化剂联用的双催化方案，能够有效利用丰富的可见光资源，实现多种新型化学键构建和官能团化，提供一个极富发展前途和应用前景的光化学转化平台。针对影响基于Ir和Ni的金属光氧化还原催化偶联反应效率的关键理论问题，本项目应用和拓展多组态微扰理论并结合电子转移速率计算，拟开展如下研究：（1）通过Ir(III)催化剂吸收/发射光谱、辐射弛豫路径的计算，建立复合物结构与其吸收/发射波长的构效关系；根据光催化剂电子结构信息，并结合激发态氧化还原电势计算，探索其触发单电子转移的热力学控制因素;（2）计算几类典型Ir-Ni金属光催化C-C偶联烷基化反应的最低能量反应途径，建立描述光催化剂、过渡金属催化剂和底物之间单电子转移的理论模型，揭示控制光催化循环的主导因素；（3）根据单电子转移始终态的热力学稳定性及其耦合，计算单电子转移速率，评估其光催化效率，据此发展普适的双金属光催化电子转移调控理论。

光诱导的电荷转移和电子转移是材料和生物科学及光催化等领域最基本的物理化学过程。因此，探索其微观机制，将有助于人们进一步探索生命的奥秘，促进理解可见光和过渡金属催化剂联用的双催化方案的触发，活化及后续光物理弛豫和化学转化，为新材料研发和应用提供重要的理论基础。本项目采用高精度的多组态微扰理论激发态计算方法，系统研究了一系列水杨醛吡啶衍生物白光材料及基于三联苯催化的光还原CO2反应中电子和电荷转移过程；通过计算其最小能量途径，建立了白光材料和光还原CO2体系的电子和电荷转移理论模型，并探索了其实现方式；在上述激发态数值模拟基础上，进行了RRKM单分子反应及Marcus电子转移速率常数计算，据此评估光诱导的电子和电荷转移实现效率，提出了电荷和电子转移触发的辐射、非辐射跃迁与化学转换机制，为白光材料、光还原CO2催化材料的分子设计提供理性方案，并为计算大型金属复合物体系激发态弛豫及电子/电荷转移过程奠定了坚实的理论基础。