Synthesis and solvatochromism of some hydroxy substituted phenyl azo pyridone dyes

Abstract

Aryl azo dyes are widely used due to their excellent physicochemical properties (primarily high value of the molar extinction coefficient and great resistance to light and wet processing) and the fact that can be obtained in a simple method of diazotization and coupling. In this paper, three new dyes of 5-(hydroxy substituted phenylazo)-3-cyano-6-hydroxy-4-methyl-2-pyridone were synthesized by a diazo coupling reaction. The obtained dyes were characterized by melting point, IR, NMR, and UV-Vis spectroscopy. Given the fact that the structure of the molecule and interactions obtained with the surrounding medium can affect its activity, the possibility of azo hydrazo tautomerism has been studied, as the influence of the position of the substituent present (orto-, meta- and para position). In addition, the effect of the solvent used was determined by applying a solvatochromic model using the LSER method (linear solvation energy relationship). Obtaining information about the inter- and intramolecular relationships that newly synthesized compounds can achieve may be of great importance for all further investigations and their potential application as biologically active compounds.

Aril azo boje imaju široku primenu zbog svojih odličnih fizičko-hemijskih svojstava (prvenstveno visoke vrednosti molarnog ekstinkcionog koeficijenta i velike otpornosti na svetlost i vlagu) i činjenice da se mogu dobiti jednostavnom metodom diazotizacije i kuplovanja. U ovom radu susintetisane tri boje 5-(hidroksi supstituisane fenilazo)-3-cijano-6-hidroksi-4-metil-2-piridona reakcijom diazo kuplovanja. Dobijene boje su okarakterisane tačkom topljenja, IR, NMR i UV-Vis spektroskopijom. S obzirom na to da struktura molekula i ostvarene interakcije sa okolnim medijumom mogu uticati na aktivnost ispitivanih jedinjenja, proučavan je solvatohromizam i moguććnost azo-hidrazon tautomerije, kao i uticaj položaja prisutnog supstituenta (orto-, meta- i para pozicija ) u strukturi ispitivanih jedinjenja. Pored toga, kvantitatifikovan je efekat korišććenih rastvarača primenom dva solvatohromna modela koristeći LSER metodu (linear solvation energy relationship). Dobijanje informacija o inter- i intra-molekulskim interakcijama koje sintetizovana jedinjenja mogu da ostvare su od velike važnosti za sva dalja istraživanja i njihovu potencijalnu primenu kao biološki aktivnih jedinjenja.