Broadband Nonlinear Absorbing Iridium(III) Complexes: Optimizing the Linear and Nonlinear Absorption via Rational Design

宽带非线性吸收铱(III)配合物：通过合理设计优化线性和非线性吸收

• 批准号: 1411086
• 负责人: WENFANG SUN
• 金额: $ 46.3万
• 依托单位: North Dakota State University Fargo
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1411086&HistoricalAwards=false
• 关键词: Broadband; Nonlinear; Absorbing; Iridium; III

This project is jointly funded by the Electronic and Photonic Materials Program (EPM) in the Division of Materials Research and by the Chemical Structure, Dynamics and Mechanisms B Program (CSDM B) in the Division of Chemistry (CHE).Non-technical Description: Nonlinear optical materials with strong and broadband nonlinear absorption (the absorptivity of the materials changes with the incident light intensity) are needed for numerous applications in information and image processing technology, such as optical switching, optical rectification, up-conversion lasing, three-dimensional optical data storage, and photodynamic therapy. This project focuses on studying the structure-property correlations in heavy transition-metal complexes with the aim to better understand how the chemical structural modifications influence their linear and nonlinear optical properties. With this understanding, synthesis of transition-metal complexes with broadband spectral (400-900 nm) and temporal (from picoseconds to continuous-wave) coverage can be a reality. The success of this project could provide a comprehensive picture of the relationship between nonlinear absorption and molecular structure, which enables a systematic design procedure for nonlinear absorbing materials. The structure-property correlations explored in this project could also be readily applied to other transition-metal complexes. This research is highly interdisciplinary. It provides students and postdoctoral researchers opportunities to gain knowledge and skills in organic synthesis, coordination chemistry, spectroscopic characterization, nonlinear optical measurements, and theoretical simulations. The interdisciplinary training motivates students' interest in research, and strengthens the workforce for the 21st Century. In addition, as part of the project effort, educational outreach activities involve the Native American students and high school students and inspire them to pursue future careers in materials research. Technical Description: Mononuclear and dinuclear heteroleptic cationic iridium(III) complexes with substituted 2-(2-quinolinyl)quinoxaline (quqo) ligand and various cyclometalating ligands are selected with the aim of understanding the structure-property correlations and achieving broadband nonlinear absorption in the Ir(III) complexes. These complexes are chosen because the strong spin-orbit coupling induced by the Ir(III) ion could lead to high triplet excited-state quantum yield, not only through rapid intersystem crossing but also through direct transition from the singlet ground state (S0) to the lowest triplet excited state (T1). The spin-forbidden S0-to-T1 absorption gives rise to broad and weak ground-state absorption in the 500-800 nm regime when appropriate diimine ligands are used, which is desirable for broadband reverse saturable absorbers. In addition, many of the Ir(III) complexes possess broadband excited-state absorption in the visible to the near-IR regions; and the structures of the Ir(III) complexes could be readily modified. In this project, mononuclear and dinuclear Ir(III) complexes with different pi-conjugations, substituents, and varied substitution positions on the quqo and/or cyclometalating ligands are synthesized. Their ground-state and excited-state properties, and nonlinear absorption, as well as the effect of inter- and intramolecular interactions on the photophysics and nonlinear absorption of these complexes in high concentration solutions and solid state are investigated systematically via a combination of spectroscopic characterizations and density functional theory (DFT) calculations. The combined experimental-theoretical approach allows the team to establish the correlations between nonlinear absorption and molecular structure of Ir(III) complexes and enables a rational design of materials with well-controlled broadband nonlinear absorption.

该项目由材料研究部的电子和光子材料计划（EMPs）和化学部的化学结构、动力学和机制B计划（CSDM B）共同资助。非技术描述：具有强宽带非线性吸收的非线性光学材料（材料的吸收率随入射光强度而变化）是信息和图像处理技术中的许多应用所需要的，例如光开关，光整流，上转换激光、三维光学数据存储和光动力疗法。该项目的重点是研究重过渡金属配合物的结构-性质相关性，旨在更好地了解化学结构修饰如何影响其线性和非线性光学性质。有了这种理解，合成具有宽带光谱（400-900 nm）和时间（从皮秒到连续波）覆盖的过渡金属络合物可以成为现实。该项目的成功将为非线性吸收与分子结构之间的关系提供一个全面的图景，从而为非线性吸收材料的设计提供一个系统的程序。本项目中探索的结构-性质相关性也可以很容易地应用于其他过渡金属配合物。这项研究是高度跨学科的。它为学生和博士后研究人员提供机会，以获得有机合成，配位化学，光谱表征，非线性光学测量和理论模拟方面的知识和技能。跨学科的培训激发了学生对研究的兴趣，并加强了21世纪世纪的劳动力。此外，作为项目工作的一部分，教育推广活动涉及美洲土著学生和高中学生，并激励他们追求材料研究的未来职业。技术说明：选择了具有取代的2-（2-喹啉基）喹喔啉（quqo）配体和各种环化配体的单核和双核杂配型阳离子铱（III）配合物，目的是理解结构-性质相关性并实现Ir（III）配合物中的宽带非线性吸收。选择这些络合物是因为由Ir（III）离子诱导的强自旋-轨道耦合可以导致高的三重激发态量子产率，不仅通过快速的系统间交叉，而且通过从单重基态（S 0）到最低三重激发态（T1）的直接跃迁。当使用适当的二亚胺配体时，自旋禁戒的S 0-T1吸收在500-800 nm范围内产生宽且弱的基态吸收，这对于宽带反饱和吸收体是期望的。此外，许多Ir（III）配合物在可见光至近红外区域具有宽带激发态吸收;并且Ir（III）配合物的结构可以容易地被修改。在这个项目中，单核和双核的Ir（III）配合物与不同的π共轭，取代基，和不同的取代位置上的quqo和/或环化配体的合成。通过光谱表征和密度泛函理论（DFT）计算，系统研究了它们的基态和激发态性质、非线性吸收以及分子间和分子内相互作用对它们在高浓度溶液和固态中的光物理和非线性吸收的影响.实验-理论相结合的方法使团队能够建立Ir（III）络合物的非线性吸收和分子结构之间的相关性，并能够合理设计具有良好控制的宽带非线性吸收的材料。