Synthesis, structure and solvatochromism of new 5-(4-substituted phenylazo)-4-(4-substituted phenyl)-6-hydroxy-3-cyano-2-pyridones

Abstract

Three series of some novel arylazo pyridone dyes, 5-arylazo-6-hydroxy-4-phenyl- 3-cyano-2-pyridone dyes, 5-arylazo-6-hydroxy-4-(4-metoxyphenyl)-3-cyano-2-pyridone dyes and 5-arylazo-6-hydroxy-4-(4-nitrophenyl)-3-cyano-2-pyridone dyes have been synthetized. The structure of the dyes was confirmed by UV-Vis, FTIR, 1H NMR and 13C NMR spectroscopy and elemental analysis. The solvatochromic behavior of the dyes was evaluated with respect to their visible absorption properties in various solvents. The azo-hydrazone tautomeric equilibration was found to depend on the substituents as well as on the solvent. These dyes exist in the hydrazone form in the solid state and in solvent DMSO-d6 and there was an equilibrium between hydrazone form and azo form in the different solvents. The Kamlet-Taft and Catalan parameters were used for describing the solutesolvent interactions and solvatochromic shifts of the visible absorption band. It was found that the solute dipolarity / polarizability (especially polarizability by Catalan equation) play an important role in the description of the pronounced solvatochromism in the studied solutions. The Catalan solvent scales were found to be more suitable for describing the solvatochromic shifts. The geometry data of the investigated dyes were obtained using DFT quantumchemical calculations. The obtained calculational results are in very good agreement with the experimental data

U okviru proučavanja strukture i karakteristika azo piridonskih boja, u čvrstom stanju i u rastvoru, su sintetisane tri nove serije arilazo piridonskih boja koje do sada nisu poznate u literaturi: 5-arilazo-6-hidroksi-4-fenil-6-cijano-2-piridonske boje, 5-arilazo-6- hidroksi-4-(4-metoksifenil)-6-cijano-2-piridonske boje i 5-arilazo-6-hidroksi-4-(4- nitrofenil)-6-cijano-2-piridonske boje. Sve azo boje su sintetisane diazotovanjem odgovarajućih 4-supstituisanih anilina i kuplovanjem dobijenih diazo soli sa odgovarajućim piridonima, prethodno dobijenim iz odgovarajućih etil-4-supstituisanih benzoilacetata i cijanoacetamida. Struktura sintetisanih azo boja je potrvđena na osnovu podataka iz UV-vis, FTIR, 1H NMR i 13C NMR spektara. Solvatohromna svojstva su određena u odnosu na njihovu apsorpciju u vidljivom delu UV-Vis spektra u različitim rastvaračima. Efekti polarnosti rastvarača, proton-donorske i proton-akceptorske karakteristike interakcije rastvarač-rastvorena supstanca su kvantitativno procenjene Kamlet-Taft-ovim i Catalan-ovim solvatohromnim modelima. Proučavanje uticaja supstituenata na arilazo komponenti na azo-hidrazon tautomeriju sintetisanih boja izvršeno je korelacijom UV-Vis apsorpcionih frekvenci Hammett-ovom jednačinom. Azo boje sintetizovane u ovoj disertaciji mogu postojati u azo i hidrazon tautomernim oblicima. Na azo-hidrazon ravnotežu veliki uticaj imaju rastvarači i supstituenti prisutni u arilazo komponenti. Rezultati ostvareni u ovom radu ukazuju na dominantan hidrazonski tautomerni oblik, kako u čvrstom stanju tako i u rastvorima azo boja u ratsvaračima različitih svojstava. Hidrazonska struktura proučavanih azo boja je potvrđena kvantno-hemijskim izračunavanjima korištenjem DFT/B3LYP metode.