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| Format: | Artículo científico |
| Language: | en |
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Sociedad Mexicana de Física A.C.
2008
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| Online Access: | https://www.redalyc.org/articulo.oa?id=57054309 |
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Table of Contents:
- Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments E. Rivera M. del P. Carreón-Castro M. Gutiérrez-Nava O.G. Morales-Saavedra J.M. Reyna-Gonzále Física, Astronomía y Matemáticas TD azo DFT dyes LMP2 Aggregation of 1-N-methylamino-4-nitroazobenzene (RED-H) was studied by UV-vis spectroscopy in solution, using different methanol:water mixtures as solvents, at different concentrations. In 100 % methanol, methanol: water 80:20 and 60:40, RED-H exhibited an maximumabsorption wavelength at ¸ = 477 nm and no aggregation was observed. By contrast, in mixtures of methanol: water 40:60 and 20:80 theappearance of an additional blue shifted band around ¸ =430 nm and a red shift of the absorption band to ¸ = 500 nm followed by a longtail confirmed the presence of both H-and J-aggregates in these solvents. Theoretical estimations of aggregate stability carried out at theLMP2/aug-cc-PVTZ(-f)//MP2/6-31G level of theory showed that the H-aggregate is the more stable one (-14.9 kcal/mol) stabilized mostlyby electronic correlation while the J-aggregate is much less stable, being stabilized by electrostatic interactions (-3.4 kcal/mol). Theoreticalestimation of the absorption spectra of RED-H, H- and J-aggregates carried out using the TD-B3LYP method reproduces the experimentallyobserved spectra. All electronic transitions show a strong charge-transfer component 2008 artículo científico 0035-001X https://www.redalyc.org/articulo.oa?id=57054309 en http://www.redalyc.org/revista.oa?id=570 Revista Mexicana de Física application/pdf Sociedad Mexicana de Física A.C. Revista Mexicana de Física (México) Num.3 Vol.54