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<p>The peculiarities of forming the spectral–luminescent characteristics of 5,15-diphenylporphyrin derivatives with various peripheral substitution architectures have been studied. Molecular conformations of derivatives with various peripheral substituents in C<sub>b</sub>- and C<sub>m</sub>-positions of the tetrapyrrole macrocycle were optimized using a density functional method. Substitution of two diametrically opposed C<sub>m</sub>-atoms was shown to lead to elongation of the macrocycle in the direction of substitution regardless of the nature of the C<sub>b</sub>-substitution. Dodecasubstituted derivatives exhibited a saddle-shaped distortion of the macrocycle. The fluorescence quantum yield of 5,15-diphenylporphyrin and its C<sub>b</sub>-alkylated derivatives decreased as compared to that of 5,10,15,20-tetrapheny lporphyrin. Introduction of nitro groups and bromine atoms in the para-position of the phenyl fragments led to enhancement and quenching of the fluorescence, respectively. It has been established that the addition of two nitro groups in the C<sub>m</sub>-positions of the 5,15-diphenylporphyrin macrocycle led to substantial bathochromic shifts of the absorption and fluorescence spectra with 100-fold fluorescence quenching due to significant gain of nonradiative deactivation of the S<sub>1</sub>-state upon forming the saddle-shaped conformer.</p>

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Role of Multicenter Interactions in Formation of Spectral–Luminescent Characteristics of 5,15-Diphenylporphyrin Derivatives

  • 期刊论文

  • 发表日期：

    2026年3月2日

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  • L. L. Gladkov,
  • D. V. Klenitsky,
  • S. A. Syrbu,
  • M. M. Kruk

摘要

The peculiarities of forming the spectral–luminescent characteristics of 5,15-diphenylporphyrin derivatives with various peripheral substitution architectures have been studied. Molecular conformations of derivatives with various peripheral substituents in Cb- and Cm-positions of the tetrapyrrole macrocycle were optimized using a density functional method. Substitution of two diametrically opposed Cm-atoms was shown to lead to elongation of the macrocycle in the direction of substitution regardless of the nature of the Cb-substitution. Dodecasubstituted derivatives exhibited a saddle-shaped distortion of the macrocycle. The fluorescence quantum yield of 5,15-diphenylporphyrin and its Cb-alkylated derivatives decreased as compared to that of 5,10,15,20-tetrapheny lporphyrin. Introduction of nitro groups and bromine atoms in the para-position of the phenyl fragments led to enhancement and quenching of the fluorescence, respectively. It has been established that the addition of two nitro groups in the Cm-positions of the 5,15-diphenylporphyrin macrocycle led to substantial bathochromic shifts of the absorption and fluorescence spectra with 100-fold fluorescence quenching due to significant gain of nonradiative deactivation of the S1-state upon forming the saddle-shaped conformer.