8-Hydroxyquinoline Monomer, Water Adducts, and Dimer. Environmental Influences on Structure, Spectroscopic Properties, and Relative Stability of Cis and Trans Conformers
| Autor: | Massimo La Deda, Pier Luigi Cristinziano, C. Minichino, Francesco Lelj, Iolinda Aiello, Mario Amati, Sandra Belviso, Mauro Ghedini |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 111:13403-13414 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp074510s |
| Popis: | The low fluorescence quantum yield of 8-hydroxyquinoline cannot be correctly interpreted without knowing the form that such a compound assumes in different environments. The commonly accepted emission-quenching excited-state proton transfer can follow different reaction paths if 8-hydroxyquinoline is dimeric or monomeric or if it exists in the form of cis and trans conformers; in this light, the knowledge of the compound form in a particular environment is basic. We have performed a spectroscopic and computational investigation aimed at the determination of the form of 8-hydroxyquinoline in different solvents. UV-vis, fluorescence, and IR spectral features have been assigned by ab initio computations based on the density functional theory and time-dependent density functional theory; the density functional theory and MP2 computations have been applied to the determination of the relative stability of the dimeric and monomeric cis and trans forms of 8-hydroxyquinoline in different solvents. Molecular dynamics computations have been used to determine the compound behavior in water solutions. According to our results, 8-hydroxyquinoline shows a clear preference for the cis conformation (as dimer or monomer), but, in water solutions, a small fraction of the trans conformation is also present. |
| Databáze: | OpenAIRE |
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