Solvatochromism, halochromism, and azo–hydrazone tautomerism in novel V‐shaped azo‐azine colorants – consolidated experimental and computational approach

Abstract

The azo–hydrazone tautomerism, solvatochromism, and halochromism in four novel V‐shaped asymmetrical acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) compounds were examined. They contain 2,7,15,16‐functionalised benzophenazine cores connected to the anchoring electron‐deficient phenyl core via azo linkers and 2,7‐position fused with anthraquinone. These compounds derived from 2‐hydroxy‐1,4‐napthaquinone (lawsone) have been prepared in moderate to good yields. The synthesis involved the diazotisation of substituted aromatic amines, coupling onto 2‐hydroxy‐1,4‐napthaquinone, and further condensing the resulting azo compounds with 1,2‐diaminoanthraquinone in acetic acid. The absorption wavelengths of the dyes in different solvents were in the range 500–720 nm. The spectral changes of the synthesised azo‐azine compounds in different pH indicated the formation of hydrazone tautomer in acidic pH and of azo tautomer in alkaline pH. Density functional theory was used to assess the tautomers in terms of geometry and position of the tautomeric equilibrium. Time‐dependent density functional theory calculations allowed us to assign the electronic transitions (>90%) of the low‐energy bands.

Synthesis of novel VO (II)‐thaizole complexes; spectral, conformational characterization, MOE‐docking and genotoxicity

“…Recently hydrazone derivatives display a key important role in medicinal, organic and inorganic chemistry as a result of their structural varieties, preparative accessibilities structures and meaningful biological activities . Hydrazone compounds are primarily a Schiff‐base group of materials having a secondary amine proton including a gorgeous family of derivatives in a variance of research areas, such as chemical and biosensors, nonlinear optics, and a variety of medical applications . Moreover, hydrazones are well known to exhibit a great ability to form highly stable complexes with several transition metals .…”

Synthesis, Solvatochromic Performance, pH Sensing, Dyeing Ability, and Antimicrobial Activity of Novel Hydrazone Dyestuffs

“…Hydrazones are originally a Schiff-base group of materials possessing a secondary amine proton comprising an important category of compounds in a diversity of research fields, such as nonlinear optics, sensors, and a variety of biological and medical applications [16][17][18][19][20][21][22][23][24][25][26].…”

Structural Modulation of Chromic Response: Effects of Binding‐Site Blocking in a Conjugated Calix[4]pyrrole Chromophore

“…Variation in the color of a dye or pigment due to changes in its immediate environment is referred to as chromism. It is a key feature that has led to sensing applications, perhaps most importantly involving acid–base equilibria (e.g. halochromism of pH indicators).…”