New Light on Late Transition Metal Complexes

在无机化学、生物无机化学和金属有机化学计划中，本项目致力于阐明铂(II)和铜(II)的正方形平面四配位络合物的激发态弛豫机制。这项工作是基于早期的观察，即此类化合物的激发态寿命受到配合物与环境的二次相互作用的强烈影响。因此，它们具有作为分子探测器和传感器的潜力。具体的研究将包括铂(II)联吡啶和铜(II)卟啉配合物在流体介质中和插入到DNA中的光化学性质的表征，以及试图通过取代联吡啶配体来延长前者的激发态寿命。将采用的技术包括发光、吸收和CD光谱，并结合猝灭反应和随温度变化的测量。对电磁辐射的吸收产生激发电子态，这些电子态可以通过非辐射(发热)或辐射(发光)途径恢复(松弛)到基态。通过对化合物发射光谱的研究，可以获得大量关于辐射弛豫化合物的电子结构的信息。辐射弛豫可以高度依赖于分子所处的环境，在有利的情况下，对发射光谱的观察可以用作分子环境的探针。这个项目的主要目标是更好地了解某些过渡金属化合物的激发态松弛发生的方式，以及这些松弛如何由分子环境决定。在许多领域都有潜在的应用，包括光传感器、光动力学癌症治疗和分子电子学。

This project, in the Inorganic, Bioinorganic, and Organometallic Chemistry Program, is concerned with elucidation of the mechanisms of excited state relaxation in square planar, four- coordinate complexes of platinum(II) and copper(II). The work is based upon earlier observations that the lifetimes of excited states of such compounds are strongly affected by secondary interactions of the complexes with their environments. As a result they have potential as molecular probes and sensors. Specific studies will include characterization of the photochemistry of platinum(II) terpyridine and copper(II) porphyrin complexes both in fluid media and intercalated into DNA, and attempts to increase the excited state lifetimes of the former complexes by modification of the terpyridine ligand through substitution. Techniques to be employed will include luminescence, absorption and CD spectroscopies in conjunction with quenching reactions and temperature dependent measurements. Absorption of electromagnetic radiation generates excited electronic states that may revert (relax) to the ground state by non-irradiative (heat generating) or irradiative (emission of light) pathways. A great deal of information can be obtained about the electronic structure of compounds that undergo irradiative relaxation by studies of their emission spectra. Irradiative relaxation can be highly dependent upon the environment in which the molecule resides and under favorable circumstances the observation of an emission spectrum can be used as a probe of the molecular environment. This project has as its major objective the development of a better understanding of the ways in which relaxation of excited states of certain transition metal compounds occur and how these are determined by the molecular environment. There are many potential applications in a number of areas including photosensors, photodynamic cancer therapy, and molecular electronics.