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Synthesis and properties of azonaphtharylamide pigments having arylamide groups at 2- and 7-positions.

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Bibliographic Details
Title: Synthesis and properties of azonaphtharylamide pigments having arylamide groups at 2- and 7-positions.
Authors: Otani, Junji1, Kikuchi, Takeshi2, Higashida, Suguru3, Harada, Takashi1, Matsumura, Michio1
Source: Journal of Molecular Structure. Mar2015, Vol. 1084, p28-35. 8p.
Subjects: Amide synthesis, Naphthol, Ring formation (Chemistry), Hyperchromic effect, Chromophores, Substituents (Chemistry)
Abstract: We studied two azonaphtharylamide pigments having arylamide groups at the 2- and 7-positions on the naphthol ring. Presence of the 7-substited amide group distinguishes the pigments from conventional azonaphtharylamide pigments derived from 3-hydroxy-2-naphthoic acid. The 7-substituent caused a hyperchromic effect but did not produce bathochromic shift in the optical absorption spectra in solution compared with the corresponding 7-unsubstituted counterparts. Molecular geometry optimizations through semi-empirical MO calculations showed that extent of the chromophore systems in the pigments with and without the 7-substituent is nearly the same, which is consistent with absence of the bathochromic shift. The MO calculations also showed that the MOs localized in the 7-substituents are involved in the electronic transitions in the longest wavelength bands of the pigments, which is responsible for the hyperchromic effect. The 7-substituted pigments exhibited better resistivity to light and heat than the 7-unsubstituted ones. [ABSTRACT FROM AUTHOR]
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Abstract:We studied two azonaphtharylamide pigments having arylamide groups at the 2- and 7-positions on the naphthol ring. Presence of the 7-substited amide group distinguishes the pigments from conventional azonaphtharylamide pigments derived from 3-hydroxy-2-naphthoic acid. The 7-substituent caused a hyperchromic effect but did not produce bathochromic shift in the optical absorption spectra in solution compared with the corresponding 7-unsubstituted counterparts. Molecular geometry optimizations through semi-empirical MO calculations showed that extent of the chromophore systems in the pigments with and without the 7-substituent is nearly the same, which is consistent with absence of the bathochromic shift. The MO calculations also showed that the MOs localized in the 7-substituents are involved in the electronic transitions in the longest wavelength bands of the pigments, which is responsible for the hyperchromic effect. The 7-substituted pigments exhibited better resistivity to light and heat than the 7-unsubstituted ones. [ABSTRACT FROM AUTHOR]
ISSN:00222860
DOI:10.1016/j.molstruc.2014.12.011