An experimental study on relationship between hammett substituent constant and electronic absorption wavelength of some azo dyes

Abstract

In this study, absorption spectra of sixteen azo dyes have been recorded in various solvents. These azo dyes have substituents such as OH, SO3H, Cl, I, NO2, C2H5 and OCH3 in different positions of phenyl ring. There is a shift in λmax whose amount is dependent upon the type and position of substituent on the ring. The effects of substituent on the absorption spectra of azo dyes are interpreted by correlation of absorption maximum wavelengths (nm) with the hammett substituent parameters. Charge transfer transitions are observed in inverse direction for azo dyes with electron acceptor substituent compared to azo dyes with electron donor.

Substituent‐Dependent Absorption Spectra, Electrochemical and Antiproliferative Activity Studies of Some 3‐(4‐(Benzyloxy)phenyl)‐5‐(4‐methoxyphenyl)‐1‐(substitutedphenyl)formazans

“…As well, formazans bearing electron rich/deficient subunits in characteristic 1,3,5‐phenyl ring were synthesized, and the effects of solvents and substituents on absorption spectra were investigated [3–7] . At the same time, formazan derivatives are be descript with their prominent π‐π* transitions on absorption spectra which are sensitive to character substituents in the phenyl rings and nature of the solvent, compared to Schiff bases having n‐π* transitions in visible region [8‐11] . Moreover, formazans derivatives have fascinated the interest due to their diverse chemical reactivities and broad spectrum of biological activities such as antimicrobial, antiviral, anti‐oxidant, analgesic, anti‐inflammatory, anticonvulsant, antiparkinsonian, antiproliferative, anthelmintic, antitubercular, and cardiovascular [12] .…”

Synthesis, structure, Hirshfeld surface, DFT, and molecular docking studies of a new organic cocrystal: creatinine:2,3‐pyridinedicarboxylic acid

“…It plays a vital role in the packing of crystals in the solid‐state through intermolecular interaction, and it has a significant influence on dipole moment, polarizability, electronic structure, and vibrational modes. [ 74 ] The Mulliken charge analysis of CR:2,3PDCA was calculated at the B3LYP method with 6‐311++G (d,p) level for the molecule under study, which is given in Table 3. All the hydrogen atoms of CR:2,3PDCA are positive, and all nitrogen atoms are negative.…”

The behaviour and properties of some acid-base indicators: a review

“…In other study, the shape of the absorption curve for MO, MR, MY and TPO changes in mixed aqueous solvents and is not that expected for a distribution function associated with a single band. The dissociation constant for these indicators is different because using different ratio of Co-solvent and also, as result relative to strength of hydrogen bonding (58). The variation in the dissociation constants of the cation acids MO and MY(2), in passing from water to alcohol, is much less than for uncharged acids.…”