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

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.

► Thirteen novel tetrakisazo dyes have been synthesized.
► Synthesized dyes contain calix[4]arene derivative.
► The solvatochromic behaviour of these dyes in various solvents was examined.
► The absorption maxima of the dyes generally indicates small bathochromic shifts depending on increasing polarity.
► We conclude from spectral results that all compounds have cone conformation.