Light Modulation of Charge Transfer Processes in Inorganic-Organic Materials

* ** 在施加外部刺激（光、电场或磁场）时发生磁、光和导电特性变化的功能材料是非易失性存储器技术、自旋电子器件和传感器发展的核心。目前的挑战涉及开发在两种功能状态之间切换的材料，用于可扩展的存储器和传感器开发。我们已经开发了一种新的策略，光驱动功能材料，通过功能化与光学双折射光致变色。光致变色剂在基态和亚稳态的电子结构不同的两种状态之间进行光诱导异构化。我们已经开发了光致变色螺恶嗪配体，可以绑定到金属中心或纳入有机多发色团阵列。一旦结合，光诱导的螺恶嗪结构的变化导致功能性目标组分（金属中心或发色团）的氧化还原电位、基态能量和激发态能量的变化。然后，这种结构变化可以触发两个有机发色团、有机配体和金属中心之间或混合价态的两个金属中心之间的能量转移和电荷转移过程。我们实验室以前的工作已经证明了光致变色诱导的电荷转移或能量转移过程的原理证明，在电子可吸收的钴络合物，荧光共轭聚合物纳米粒子和荧光有机二联体。在这个建议中，我们描述了实验设计，以了解基本的结构和电子因素，支配这些现象，光致变色门控过程的限制，以及动力学和热力学因素，调节信噪比优化光诱导门控传感器和存储器应用。* 在所提出的工作中，我们将研究（i）控制光化学和热过程的结构参数，以及光致变色螺恶嗪在开/关状态下的电子结构（ii）将光致变色配体整合到一系列电子双金属络合物中以建立控制这些系统中的氧化和自旋状态切换的参数，（iii）将光致变色配体整合到光致变色螺恶嗪中。

* **Functional materials that undergo changes in magnetic, optical, and conducting properties upon application of external stimuli (light, electric field, or magnetic field) are central to the development of non-volatile memory technologies, spintronics devices, and sensors. Current challenges involve developing materials that switch between two functional states with light for scalable memory and sensor development. We have developed a novel strategy for light-driven functional materials through functionalization with optically bistable photochromes. Photochromes undergo light-induced isomerization between two states that differ in the electronic structures of their ground and metastable states. We have developed photochromic spirooxazine ligands that can be bound to metal centers or incorporated into organic multichromophoric arrays. Once bound, light-induced changes in spirooxazine structure lead to changes in the redox potential, ground state energies, and excited state energies at the functional target component (metal center or chromophore). Such structural changes can then trigger energy-transfer, and charge-transfer processes between two organic chromophores, organic ligands, and metal centers, or between two metal centers in a mixed valence state. Previous work in our lab has demonstrated proof-of-principle for photochrome-induced charge transfer or energy transfer processes in an electronically bistable cobalt complex, fluorescent conjugated polymer nanoparticles, and fluorescent organic dyads. In this proposal, we describe experiments designed to understand the fundamental structural and electronic factors that govern these phenomena, the limits of photochrome-gated processes, and the kinetic and thermodynamic factors that regulate signal-to-noise ratios for optimizing light-induced gating for sensors and memory applications. *** In the proposed work, we will investigate (i) the structural parameters that govern photochemical and thermal processes, and electronic structure in open/closed states of photochromic spirooxazines (ii) integrate photochromic ligands into a series of electronically bistable metal complexes to establish the parameters that govern switching of oxidation and spin states in these systems, (iii) incorporate photochromes