Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments
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 maximum absorption wavelength at λ = 477 nm and no aggregation was observed. By contrast, in mixtures of methanol: water 40:60 and 20:80 the appearance of an additional blue shifted band around λ =430 nm and a red shift of the absorption band to λ = 500 nm followed by a long tail confirmed the presence of both H-and J-aggregates in these solvents. Theoretical estimations of aggregate stability carried out at the LMP2/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 mostly by electronic correlation while the J-aggregate is much less stable, being stabilized by electrostatic interactions (-3.4 kcal/mol). Theoretical estimation of the absorption spectra of RED-H, H- and J-aggregates carried out using the TD-B3LYP method reproduces the experimentally observed spectra. All electronic transitions show a strong charge-transfer component.
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Sociedad Mexicana de Física
2008
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oai:scielo:S0035-001X20080003000092009-04-14Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environmentsCarreón-Castro,M. del PGutiérrez-Nava,MMorales-Saavedra,O.GReyna-González,J.MRivera,E Aggregation azo-dyes DFT LMP2 TD-DFT optical properties 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 maximum absorption wavelength at λ = 477 nm and no aggregation was observed. By contrast, in mixtures of methanol: water 40:60 and 20:80 the appearance of an additional blue shifted band around λ =430 nm and a red shift of the absorption band to λ = 500 nm followed by a long tail confirmed the presence of both H-and J-aggregates in these solvents. Theoretical estimations of aggregate stability carried out at the LMP2/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 mostly by electronic correlation while the J-aggregate is much less stable, being stabilized by electrostatic interactions (-3.4 kcal/mol). Theoretical estimation of the absorption spectra of RED-H, H- and J-aggregates carried out using the TD-B3LYP method reproduces the experimentally observed spectra. All electronic transitions show a strong charge-transfer component.info:eu-repo/semantics/openAccessSociedad Mexicana de FísicaRevista mexicana de física v.54 n.3 20082008-06-01info:eu-repo/semantics/articletext/htmlhttp://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0035-001X2008000300009en |
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Carreón-Castro,M. del P Gutiérrez-Nava,M Morales-Saavedra,O.G Reyna-González,J.M Rivera,E |
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Carreón-Castro,M. del P Gutiérrez-Nava,M Morales-Saavedra,O.G Reyna-González,J.M Rivera,E Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments |
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Carreón-Castro,M. del P Gutiérrez-Nava,M Morales-Saavedra,O.G Reyna-González,J.M Rivera,E |
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Carreón-Castro,M. del P |
title |
Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments |
title_short |
Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments |
title_full |
Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments |
title_fullStr |
Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments |
title_full_unstemmed |
Optical properties and aggregation of 1-N-methylamino-4'-nitroazobenzene in various environments |
title_sort |
optical properties and aggregation of 1-n-methylamino-4'-nitroazobenzene in various environments |
description |
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 maximum absorption wavelength at λ = 477 nm and no aggregation was observed. By contrast, in mixtures of methanol: water 40:60 and 20:80 the appearance of an additional blue shifted band around λ =430 nm and a red shift of the absorption band to λ = 500 nm followed by a long tail confirmed the presence of both H-and J-aggregates in these solvents. Theoretical estimations of aggregate stability carried out at the LMP2/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 mostly by electronic correlation while the J-aggregate is much less stable, being stabilized by electrostatic interactions (-3.4 kcal/mol). Theoretical estimation of the absorption spectra of RED-H, H- and J-aggregates carried out using the TD-B3LYP method reproduces the experimentally observed spectra. All electronic transitions show a strong charge-transfer component. |
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Sociedad Mexicana de Física |
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2008 |
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http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0035-001X2008000300009 |
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1756219905724645376 |