Luminescent Organometallic Complexes with Fast Radiative Rates

在化学部化学结构、动力学和机理b （CSDM-B）项目的支持下，休斯顿大学化学系的Thomas Teets正在研究提高磷光金属配合物辐射衰减率的策略。磷光金属配合物已被用于各种光电应用，最著名的是有机发光二极管（oled），一种广泛应用于彩色显示器和其他消费产品的照明技术。该项目的目标是在几种不同类别的磷光化合物中使用互补的分子设计策略，以增加其辐射率，从而提高生产效率和耐用性的有机发光二极管的长期影响。这项工作结合了创新的合成化学来制造新分子和深入的光物理表征来测量光发射的颜色轮廓、效率和时间尺度。站在有机金属化学和光化学的界面上，本研究旨在产生深刻的结构-性质关系，从而发现性能最好的磷光金属配合物。该项目的另一部分将开发一个公开可用的光化学活性化合物网络数据库，允许各级研究人员在数据库中搜索和分类具有特定特性的化合物。最后，该研究项目将作为实验物理无机化学研究的本科生和研究生研究人员的培训基地，为未来的科技劳动力做出贡献。根据该奖项，测试研究团队将寻求三种互补策略，以提高有机金属荧光粉的辐射率和光致发光量子产率。前两个重点是蓝色磷光，这仍然是光电领域最重大的技术挑战之一。铂乙基化合物是一类很有前途的蓝磷光化合物，但其缓慢的辐射速率阻碍了其在oled中的广泛应用。该项目将引入“次级重金属效应”，通过用其他重金属装饰铂芳基乙酰醚化合物的外围，作为增加辐射率的策略。这些方法主要集中在吡啶取代的乙酰基能与多种重金属添加剂配位、金属直接与乙酰基π电子结合以及在芳基乙酰基配体上形成共价金-碳键。虽然有机铂配合物是这项工作的主要焦点，但具有快速辐射率的蓝色磷光的第二种策略将涉及一类新的环金属化乙酰化铱化合物。这些化合物结合了芳基乙酰基产生的尖锐的蓝色磷光，以及铱产生的固有的更大的自旋轨道耦合和更快的辐射速率。最后，这个项目的最后一个主要推力集中在环金属化铂配合物上，重点是在光谱的低能量区域（红色到近红外）发光。这些化合物将具有富含电子的辅助配体，可以稳定电荷转移态，增加激发态自旋轨道耦合，并增加辐射速率常数。空间效应对环金属化和辅助配体的影响也将被研究，这对于最小化聚集和抑制非辐射速率是重要的。该奖项反映了美国国家科学基金会的法定使命，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。

WIth support from the Chemical Structure, Dynamics & Mechanisms-B (CSDM-B) Program of the Chemistry Division, Thomas Teets of the Department of Chemistry at University of Houston is investigating strategies to increase the radiative decay rates in phosphorescent metal complexes. Phosphorescent metal complexes have been used in a variety of optoelectronic applications, most notably organic light-emitting diodes (OLEDs), a lighting technology that is widely used in color displays and other consumer products. The goal of this project is to use complementary molecular design strategies in a few different classes of phosphorescent compounds to increase their radiative rates, with long-term implications of producing OLEDs with improved efficiency and durability. The work combines innovative synthetic chemistry to make new molecules and in-depth photophysical characterization to measure the color profile, efficiency, and timescale of light emission. Standing at the interface of organometallic chemistry and photochemistry, this research aims to produce insightful structure-property relationships that lead to the discovery of top-performing phosphorescent metal complexes. Another part of this project will develop a publicly available web database of photochemically active compounds, allowing researchers at all levels to search and sort the database for compounds that have specific properties of interest. Finally, this research project will serve as a training ground for undergraduate and graduate researchers in experimental physical inorganic chemistry research to contribute to the future science and technology workforce.Under this award, the Tests research team will pursues three complementary strategies for increasing the radiative rates and photoluminescence quantum yields of organometallic phosphors. The first two focus on blue phosphorescence, which remains one of the most significant technical challenges in the optoelectronic field. Platinum acetylide compounds are a promising class of blue-phosphorescent compounds, but their slow radiative rates have hindered their widespread deployment in OLEDs. This project will introduce the “secondary heavy-metal effect” as a strategy to increase radiative rates, by decorating the periphery of platinum aryl acetylide compounds with other heavy metals. These approaches center on pyridyl-substituted acetylides which can coordinate to a variety of heavy metal additives, binding of coinage metals directly to the acetylide π-electrons, and covalent gold-carbon bond formation on the aryl acetylide ligands. Although organoplatinum complexes are the major focus of this work, a second strategy for blue phosphorescence with fast radiative rates will involve a new class of cyclometalated iridium acetylide compounds. These compounds will combine the advantageous sharp blue phosphorescence originating from aryl acetylides with the inherently larger spin-orbit coupling and faster radiative rates that iridium engenders. Finally, the last major thrust of this project centers on cyclometalated platinum complexes, with an emphasis on luminescence in the lower-energy regions (red to near-infrared) of the spectrum. These compounds will feature electron-rich ancillary ligands that can stabilize charge-transfer states, increase excited-state spin-orbit coupling, and augment radiative rate constants. Steric effects on both the cyclometalating and ancillary ligand will also be investigated and are important for minimizing aggregation and suppressing nonradiative rates.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.