Two-Photon Spectroscopy of the Q-Bands of meso-Tetraphenyl-Porphyrin and -Chlorin Framework Derivatives

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• 作者：Jordan A. Greco ; Sumie Shima ; Nicole L. Wagner ; Jason R. McCarthy ; Karissa Atticks ; Christian Br眉ckner ; Robert R. Birge
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：February 19, 2015
• 年：2015
• 卷：119
• 期：7
• 页码：3711-3724
• 全文大小：971K
• ISSN：1932-7455

文摘

The two-photon absorption and excitation spectra in the Q-band region (900鈥?360 nm) were measured for a number of porphyrinoids, including simple porphyrins (porphin, meso-tetraphenyl-porphyrin), chlorins (meso-tetraphenyl-2,3-dimethoxychlorin), and porphyrin and chlorin-like analogues (meso-tetraphenyl-porpholactone and meso-tetraphenyl-porpholactol, respectively). These molecules were chosen to provide a series of compounds that differed structurally only in 鈥渟ingle points鈥? Vibronic structure is observed in the two-photon spectra for all porphyrinoids investigated, but their relative intensities show distinct differences from the vibronic development observed in the corresponding one-photon spectra. A Franck鈥揅ondon analysis provides insight into the observed differences. The calculations also indicate that the two-photon absorptivities are associated primarily with Type I processes involving multiple intermediate states, and that accurate assignment requires a summation over at least 30 intermediate states. The Q-bands of the meso-tetraphenyl-2,3-dimethoxychlorin exhibit anomalously high two-photon absorptivities, which we have traced to facile conformational distortion of the chlorin chromophore. Calculations indicated that the relative Q-band absorptivities are sensitive to the phase and magnitude of the chlorin ring distortions.