Red Emitting Monoazo Disperse Dyes with Phenyl(1H-benzoimidazol-5-yl) Methanone as Inbuilt Photostabilizing Unit: Synthesis, Spectroscopic, Dyeing and DFT Studies

Abstract

Synthesis of three novel phenyl(1H-benzoimidazol-5-yl)methanone based fluorescent monoazo disperse dyes and their characterization by spectroscopic methods (H NMR, C NMR, IR and MS) are presented. Insertion of phenyl(1H-benzoimidazol-5-yl)methanone moiety bring about induced fluorescence properties and enhanced photostability as compared to the previously reported analogues (CI Solvent Yellow 14, 4-diethylamino-2-hydroxy-1-diazobenzene and 7-(diethylamino)-4-hydroxy-3-(phenyldiazenyl)-2H-chromen-2-one). Synthesized phenyl(1H-benzoimidazol-5-yl)methanone based dyes exhibited red-shifted absorption maxima (497-516 nm), high molar extinction coefficients and are emitting in the far-red region (565-627 nm). Moreover, naphthalene-comprising dyes showed negative solvatochromism while N,N-diethylamine comprising dyes showed positive solvatochromism and are in good agreement with solvent polarity graphs and the computed energy levels of highest occupied and lowest unoccupied molecular orbitals. Synthesised dyes have better photostability (light fastness) and sublimation fastness on dyed polyester and nylon compared to reported analogues. DFT calculated energies, electrophilicity index and Frontier Molecular Orbitals (FMO's) enabled to evaluate the stabilities of azo and hydrazone forms of the dyes.

Synthesis and absorption properties of five new heterocyclic disazo dyes containing pyrazole and pyrazolone and their acute toxicities on the freshwater amphipod Gammarus roeseli

“…Compounds with high ε values can be used in potential applications even in low gloss conditions and show sublimation fastness. 33 In this study, the dye 3b showed higher ε values than the other dyes in both DMSO and DMF (Table 2). This could have resulted from the resonance stability of the nitro group bonded to the phenyl ring in the dye 3b.…”

Substituent and Solvent Polarity on the Spectroscopic Properties in Azo Derivatives of 2-Hydroxynaphthalene and Their Difluoroboranes Complexes

“…The solvatochromic behavior of the dyes 1–4 and 5–8 was studied with the help of Lippert [ 46 , 63 ] and Bakhshiev [ 63 ] plots. Lippert’s theory assumes that general solvent effects are present in the solvent medium and the polarizability of the solute molecule is neglected.…”

New disazo dyes derived from aminopyrazoles: synthesis, spectroscopic properties, computational study and structural properties

“…In this study, the 3c compound had higher ε and f values than other compounds (Table 4B). The compounds with high ε values may have potential applications in low gloss conditions and show greater sublimation fastness with respect to the others 47,48 …”