Excited-State Properties of Multiply-Excited Oligonuclear Coordination Compounds

拟议的两个小组之间的联合项目从合成和物理化学的目标调查超快激发态过程中的三和寡聚络合物纳入Ru（II），Fe（II），Os（II）和Cr（III）中心后，激发的金属-配体电荷转移。到目前为止，主要是在低强度激发下的激发态弛豫动力学的三和寡配合物已被报道。然而，在这项研究中，将采用高激发强度的制度。第一次，在这一制度的系统研究将进行详细的结构动力学关系。该项目将解决与多重激发寡核苷酸复合物的激发态性质相关的核心问题，例如，如果激子-激子湮灭的概念，如从共轭聚合物的电子物理学中已知的，也可以被转化为分子配位化合物，以及如何通过复杂的设计来调节其动力学。此外，详细的动力学受阻的分子内能量转移将被利用-最近报道的过程中的一个示例性的三核供体-受体-供体系统的过程。该项目的主题是光致多电子过程的发展，以及三金属和寡金属络合物中激发态的理解和设计。在联合前期工作的继续，混合金属配合物与α-共轭bisterpyridine配体将被用作积木和调查关于一些机械方面：多远的分子设计的影响三重态-三重态激发态湮灭后，光激发两个不同的金属中心在一个单一的分子组装？分子设计能否用来控制三核给体-受体-给体配合物中的分子内能量转移速率？如果扩展复合物内的供体单元的数量增加，上述过程将如何受到影响（假设不止一个供体位点被激发）？

The proposed joint project between two groups from synthetic and physical chemistry targets the investigation of ultrafast excited-state processes in tri- and oligonuclear complexes incorporating Ru(II), Fe(II), Os(II) and Cr(III) centers upon excitation of the metal-to-ligand charge-transfer. Up to now mainly the excited-state relaxation dynamics of tri- and oligonuclear complexes under low-intensity excitation have been reported. In this study, however, the regime of high-excitation intensities will be employed. For the first time, a systematic study in this regime will be performed to derive detailed structure-dynamics relationships. The project will address central questions associated with the excited-state properties of multiply excited oligonuclear complexes, e.g., if the concept of exciton-exciton annihilation, as known from the photophysics of conjugated polymers, can also be translated to molecular coordination compounds and how its kinetics can be tuned by complex design. Moreover, the details of kinetically hindered intramolecular energy transfer will be exploited – a process recently reported process in an exemplary trinuclear donor-acceptor-donor system. The main theme of the proposed project is related to the development of photoinduced multi-electron processes and the understanding as well as the design of excited states in tri- and oligonuclear metal complexes. In continuation of the joint preliminary work, mixed-metal complexes with -conjugated bisterpyridine ligands will be employed as building blocks and investigated regarding a number of mechanistic aspects: How far does the molecular design effect the triplet-triplet excited-state annihilation upon photoexcitation of two distinct metal centers within a single molecular assembly? Can the molecular design be utilized to manipulate the rate of kinetically hindered intramolecular energy transfer within trinuclear donor-acceptor-donor complexes? How are the aforementioned processes affected if the number of donor units within the extended complexes is increased (given that more than a single donor site is excitated)?