Abstract Parent, unsubstituted free base hemiporphycene, a constitutional isomer of porphyrin, was synthesized only a few years ago, and the detailed characterization of vibrational structure is lacking. We studied vibrations of hemiporphycene using site-selected fluorescence and IR measurements in low temperature argon and nitrogen matrices, combined with recording Raman spectra of polycrystalline samples. Temperature dependence of IR and Raman spectra was also investigated. The spectra were analysed with the help of DFT calculations of vibrational energies and transition intensities. Most of the bands observed in the 600-1600 cm−1 range could be reliably assigned. Moreover, it was possible to photoconvert the lowest energy trans1 tautomer, the only species present at low temperatures, into a higher energy trans2 form. However, this process is not efficient and strongly depends on the chromophore microenvironment.

中文翻译：

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半卟啉振动结构的基质分离研究

摘要 父体未取代的游离碱半卟啉是卟啉的一种结构异构体，是几年前合成的，缺乏详细的振动结构表征。我们使用低温氩和氮基质中的位点选择荧光和红外测量，结合记录多晶样品的拉曼光谱，研究了半卟啉的振动。还研究了 IR 和拉曼光谱的温度依赖性。借助振动能和跃迁强度的 DFT 计算分析光谱。在 600-1600 cm-1 范围内观察到的大部分波段都可以可靠地分配。此外，可以将最低能量的 trans1 互变异构体（低温下唯一存在的物种）光转换为更高能量的 trans2 形式。然而，