Resonance Raman Spectroscopy and Quantum-Chemical Calculations of Push-Pull Molecules: 4-Hydroxy-4'-nitroazobenzene and Its Anion

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• 作者：Rô ; mulo A. Ando ; Jos&eacute ; L. Rodrí ; guez-Redondo ; A. Sastre-Santos ; Fernando Ferná ; ndez-Lá ; zaro ; Gianluca C. Azzellini ; Antonio C. Borin ; Paulo S. Santos
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：December 27, 2007
• 年：2007
• 卷：111
• 期：51
• 页码：13452 - 13456
• 全文大小：121K
• 年卷期：v.111,no.51(December 27, 2007)
• ISSN：1520-5215

文摘

The deprotonation of the push-pull molecule 4-hydroxy-4'-nitroazobenzene leads to a substantial variationin the charge distribution over the donor and acceptor moieties in the D--azo--A system. The extra chargestabilizes the excited state, leading to a drastic red shift of ca. 100 nm in the _max of the electronic transitionand consequently causes significant changes in the resonance Raman enhancement profiles. In the neutralspecies the chromophore involves several modes, as (CN), (NN), and _s(NO₂), while in the anion theselective enhancement of the _s(NO₂) and (CO^-) modes indicates a greater geometric variation of the NO₂and CO^- moieties in the resonant excited electronic state. The interpretation of the electronic transitions andthe vibrational assignment are supported by quantum-mechanical calculations, allowing a consistent analysisof the enhancement patterns observed in the resonance Raman spectra.