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Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.49A [2010] >
IJC-A Vol.49A(04) [April 2010] >
| Title: | Azonium-ammonium tautomerism and inclusion complexation of 4-amino-2′, 3-dimethylazobenzene |
| Authors: | Prabhu, A Antony Muthu
Venkatesh, G
Sankaranarayanan, R K
Siva, S
Rajendiran, N |
| Keywords: | Spectral studies
Tautomerism
Inclusion compounds
Azo compounds
Azobenzenes
Aminoazobenzenes
Cyclodextrins |
| Issue Date: | Apr-2010 |
| Publisher: | CSIR |
| Abstract: | The spectral
characteristics of 4-amino-2′,3-dimethylazobenzene (GBC), 4-aminoazobenzene
(AAB) and azobenzene (AB) have been studied in various solvents, varying
hydrogen ion concentrations and in  -cyclodextrin
(-CD). The
inclusion complexes of GBC, AAB and AB with -CD have been analysed by
UV-visible, fluorometry, FT-IR, 1H NMR, SEM and Cache-DFT methods.
The solvent study shows that the azo form is present only in GBC and AAB
molecules. No significant spectral difference is observed in GBC indicating
that the presence of two methyl groups does not effectively change the spectral
behaviour as compared to that of AAB. In acid solutions, unusual red shift is
observed in the monocation suggesting that the azonium-ammonium tautomer is
present in both molecules. The absorption maximum at ~500 nm, is due to the
azonium cation while that at ~320 nm originates from the ammonium cation. In -CD solutions, the
increase in the fluorescence intensity and large bathochromic shift in S1
state indicates that both GBC and AAB form 2:2 inclusion complex, whereas AB
forms 1:1 inclusion complex. Also, head-to-head dimer is formed in both the
aminoazobenzene compounds. |
| Page(s): | 407-417 |
| Source: | IJC-A Vol.49A(04) [April 2010]
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