Theoretical Studies on Structures and Spectroscopic Properties of Self-Assembled Bis(2,4,8,10-tetramethyl-9-methoxycarbonylethyldipyrrin-3-yl)methane with Co(II)

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• 作者：Wei Li*^† ; ; Feng Yang^† ; ; Zengdong Wang^† ; ; Jiming Hu*^‡ ; ; Jinshi Ma^§ ;
• 刊名：Journal of Physical Chemistry A
• 出版年：2009
• 出版时间：April 9, 2009
• 年：2009
• 卷：113
• 期：14
• 页码：3375-3381
• 全文大小：206K
• 年卷期：v.113,no.14(April 9, 2009)
• ISSN：1520-5215

文摘

We report a combined experimental and computational study of the large self-assembly complex (CoL)₂ [L= bis(2,4,8,10-tetramethyl-9-methoxycarbonylethyldipyrrin-3-yl)methane] containing 172 atoms. An extensive density functional theory (DFT) and time-dependent DFT study of this complex in gas phase and in CH₂Cl₂ solution was performed, investigating the effect of substitutions of methyl and methyl propionate on the electronic structure and optical properties of this complex. The calculated IR and Raman spectra are in excellent agreement with the experiment, thus allowing a detailed assignment of the vibrational absorption bands. Comparing the vibrational spectrum of (CoL)₂ with that of (ZnL′)₂ [L′ = bis(2,4-dimethyldipyrrin-3-yl)methane], the substitution of methyl on the C_β atom results in sizable shifts on the same modes; particularly in the case of mode υ(C_β−C_β), the shift is more than 20 cm⁻¹. The lowest 70 singlet−singlet spin-allowed excited states were taken into account for the calculation by TDDFT in gas phase and PCM-TDDFT in CH₂Cl₂ solution. Theoretical calculations provide a good description on positions of the two band maximums in observed spectrum but predict a contrary relatively intensity for these two bands. In the UV−vis absorption spectrum of (CoL)₂ complex, the band maximum at 525.5 nm is mainly attributed to the π→π* transition. The band maximum at 488.1 nm is originated from metal−ligand charge-transfer (MLCT) transition mixed with interligand π→π* transition.