Theoretical Investigations on Electronic Structures and Absorption Spectra of Unsymmetrical Metal-coordinated Neo-confused Porphyrin in Various Solvents

【摘要】 Though the photo-physical properties of free base porphyrin are attractive, there are still problems for the materials with weak and narrow range absorption of visible light. The unsymmetrical neo-confused porphyrin derivatives were introduced as novel materials for the improvement of photo-chemical and photo-physical properties. The density function theory(DFT)and time dependent density function theory(TDDFT) were applied to calculate the absorption spectrum of unsymmetrical neo-confused porphyrin(N-CP) and metal-coordinated N-CP in various solutions. The Ni and Zn coordinated neo-confused porphyrin dipole moment values are smaller than the values of prototype porphyrin(Pro P) and N–CP. According to the electrophilicity index ω, Ni coordinated N–CP(Ni–N–CP) is susceptible to the polarity of solvents, while the Zn coordinated derivative(Zn–N–CP) is more immune to the solvent environment. Unlike the Gouterman’s four frontier orbital model of common porphyrin materials, the electron transitions of N–CPs and metalcoordinated N–CPs from H–2 or lower molecular orbitals also contribute to ultraviolet and visible absorption. Most of oscillator strength f values of Zn–N–CP are significantly higher than the values of Ni–N–CP, which reflects the higher absorption intensity of Q and Soret bands. The maximum wavelength at 702.2 nm in vacuum drew our attention to the novel material. The broad absorption range, intense red-shifted Q band and higher stability in solvents suggest that N–CPs, especially Zn–N–CP, can be one class of new candidate dye-sensitized materials.更多还原

【Abstract】 Though the photo-physical properties of free base porphyrin are attractive, there are still problems for the materials with weak and narrow range absorption of visible light. The unsymmetrical neo-confused porphyrin derivatives were introduced as novel materials for the improvement of photo-chemical and photo-physical properties. The density function theory(DFT)and time dependent density function theory(TDDFT) were applied to calculate the absorption spectrum of unsymmetrical neo-confused porphyrin(N-CP) and metal-coordinated N-CP in various solutions. The Ni and Zn coordinated neo-confused porphyrin dipole moment values are smaller than the values of prototype porphyrin(Pro P) and N–CP. According to the electrophilicity index ω, Ni coordinated N–CP(Ni–N–CP) is susceptible to the polarity of solvents, while the Zn coordinated derivative(Zn–N–CP) is more immune to the solvent environment. Unlike the Gouterman’s four frontier orbital model of common porphyrin materials, the electron transitions of N–CPs and metalcoordinated N–CPs from H–2 or lower molecular orbitals also contribute to ultraviolet and visible absorption. Most of oscillator strength f values of Zn–N–CP are significantly higher than the values of Ni–N–CP, which reflects the higher absorption intensity of Q and Soret bands. The maximum wavelength at 702.2 nm in vacuum drew our attention to the novel material. The broad absorption range, intense red-shifted Q band and higher stability in solvents suggest that N–CPs, especially Zn–N–CP, can be one class of new candidate dye-sensitized materials.更多还原