Synthesis and absorption spectra of some novel hetaryltetrakisazocalix[4] arene derivatives

Abstract

In this study, a convenient method for the synthesis of thirteen novel tetrakisazo dyes containing 25,27-bis-(4-nitrobenzyloxy)-26,28-dihydroxycalix[4] arene have been described. 5,11,17,23-Tetra-tert-butyl-25,26,27,28- tetrahydroxycalix[4]arene, 25,26,27,28-tetrahydroxycalix[4]arene and 25,27-bis-(4-nitrobenzyloxy)-26,28-dihydroxycalix[4]arene were synthesized. 2-arylhydrazone-3-ketiminobutyronitriles 1(a-m) were synthesized and reacted with hydrazine hydrate to afford the corresponding 5-amino-4-arylazo-3-methyl-1- H-pyrazoles 2(a-m). Thirteen novel hetaryltetrakisazocalix[4]arene derivatives 6(a-m) were achieved by diazotisation of 5-amino-4-arylazo-3-methyl-1-H- pyrazoles using nitrosylsulphuric acid, coupling with 25,27-bis-(4- nitrobenzyloxy)-26,28-dihydroxycalix[4]arene. The obtained hetaryltetrakisazocalix[4]arene dyes 6(a-m) were characterized based on FT-IR, 1H NMR and Mass spectroscopic techniques as well as Elemental Analysis. The solvatochromic behaviour of these dyes in various solvents was examined. Acid-base effect on the visible absorption maxima of the dyes were also reported. © 2012 Elsevier Ltd. All rights reserved.