Time-Resolved Resonance Raman Spectroscopy of Metalloporphyrins in Excited Electronic States

哈弗福德学院的胡里奥·C·德·保拉得到了实验物理化学计划的支持，该计划利用时间分辨共振拉曼光谱研究金属卟啉激发态的性质。他的研究重点将是(A)研究四苯基卟啉构象在三重态激发态之间的平衡动力学，(B)通过改变Ru和镍离子络合物上的取代基来区分电荷转移激发态和金属中心激发态，以及(C)指认四苯基卟啉铜的时间分辨共振拉曼光谱。金属卟啉具有丰富的光化学，可应用于人工光合作用、分子电子学和光动力学癌症治疗。例如，已知游离基锌和铜卟啉在体外会敏化肿瘤坏死。此外，Ru的聚合物是光导性的，可以作为分子导线。非平面金属卟啉正成为许多此类应用的重要化合物，因为卟啉环的扭曲会调节电化学和光化学性质。这些对金属卟啉激发电子态的研究将有助于更好地理解它们的光化学活性。

Julio C. de Paula of Haverford College is supported by the Experimental Physical Chemistry Program to investigate the nature of excited states of metalloporphyrins using time-resolved resonance Raman spectroscopy. The focus of his studies will be (a) to investigate equilibrium dynamics between conformers of tetraphenylporphyrins in triplet excited states, (b) to distinguish between charge-transfer and metal-centered excited states by varying the substituents on ruthenium and nickel ion complexes, and (c) to assign the time-resolved resonance Raman spectra of the cupric tetraphenylporphyrins. Metalloporphyrins have a rich photochemistry that may be applied to artificial photosynthesis, molecular electronics, and photodynamic cancer therapy. For example, free-base zinc and cupric porphyrins are known to sensitize tumor necrosis in vitro. Further, polymers of ruthenium porphyrins are photoconductive and can act as molecular wires. Non-planar metalloporphyrins are emerging as important compounds for a number of these applications, because distortions of the porphyrin ring modulate electrochemical and photochemical properties. These studies of the excited electronic states of metalloporphyrins will lead to a better understanding of their photochemical activity.