CAS: Functionalization of Earth-Abundant, Molecular Group 4 Photosensitizers for Photochemical Applications

西弗吉尼亚大学化学系的卡斯滕·米尔斯曼在化学系化学结构、动力学和机理B(CSDM-B)计划和已建立的刺激竞争研究计划(EPSCoR)的支持下，正在开发基于可用于光化学应用的富含稀土的第4族元素的分子过渡金属光敏剂的新合成路线。这项研究的目标是提供廉价和容易获得的光吸收分子，这些分子具有生产太阳能燃料、在极性溶液中进行光催化和构建光伏器件(例如染料敏化太阳能电池)所需的特性。从拟议的工作中获得的基本见解将扩大可用的光敏剂的范围，并允许以更可持续的方式进行有针对性的光收集分子设计。拟议的研究将合成有机化学和无机化学的元素与详细的光物理研究相结合，允许对具有不同兴趣的研究生和本科生进行培训和教育，以期在未来的科学家职业生涯中发挥作用。具有长寿命配体-金属电荷转移(LMCT)激发态的早期过渡金属光敏剂是一类新兴的无机生色团，已在光催化、光子上转换和生物传感方面得到了应用。建议的研究包括利用现有分子结构的合成后修饰来(I)提高性能关键参数，如在极性溶剂中的稳定性和溶解性；(Ii)在金属氧化物表面引入锚基，从而促进光驱动空穴注入到p型半导体中；(Iii)探索分子对称性对第四族光敏剂的光学性质(例如，系间交叉速率、寿命和量子产率)的影响，并提供不对称络合物，以促进可见光激发下的定向电荷转移；以及(Iv)探索第4组光敏剂设计的化学空间，并提供对早期过渡金属发色团基本设计原则的基本理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

WIth support from the Chemical Structure, Dynamics & Mechanisms-B (CSDM-B) Program of the Chemistry Division and the Established Program to Stimulate Competitive Research (EPSCoR), Carsten Milsmann of the Department of Chemistry at West Virginia University is developing new synthetic routes to molecular transition metal photosensitizers based on earth abundant group 4 elements that can be utilized in photochemical applications. The goal of this research is to provide cheap and readily available light-absorbing molecules with characteristics required for solar fuels production, photocatalysis in polar solutions, and the construction of photovoltaic devices (e.g., dye-sensitized solar cells). Fundamental insights gained from the proposed work will broaden the scope of available photosensitizers and allow the targeted design of light-harvesting molecules in a more sustainable way. The proposed studies combine elements of synthetic organic and inorganic chemistry with detailed photophysical investigations, allowing for training and education of graduate and undergraduate students with diverse interests for their future careers as scientists. Early transition metal photosensitizers with long-lived ligand-to-metal charge transfer (LMCT) excited states are an emerging class of inorganic chromophores that have found application in photocatalysis, photon upconversion, and biological sensing. The proposed research includes the use of postsynthetic modification of existing molecular architectures to (i) improve performance critical parameters such as stability and solubility in polar solvents; (ii) incorporate anchoring groups for immobilization on metal oxide surfaces, thereby facilitating light-driven hole injection into p-type semiconductors; (iii) explore the influence of molecular symmetry on the optical properties of group 4 photosensitizers (e.g. intersystem crossing rates, lifetimes, and quantum yields) and provide asymmetric complexes to facilitate directional charge transfer upon visible-light excitation; and (iv) explore the chemical space for group 4 photosensitizer design and provide fundamental understanding of the underlying design principles for early transition metal chromophores.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.