Solvent Influence on the Electronic Absorption Spectra of Some Azoaromatic Compounds

Abstract

Solvent-induced effects on the π -π * electronic absorption band frequencies of some azobenzene derivatives are described in terms of dipole-dielectric, solute-solvent, and hydrogen bonding interactions. A multiple linear regression equation for ν max was developed based on polarizability-polarity parameters and KamletTaft solvatochromic parameters. Although the polarizability is a major contributor to the interactions in solutions, parameters related to the solvent polarity, hydrogen bond acidity, and hydrogen bond basicity are also statistically significant in determining the spectral shifts.

Novel chromogenic, guest-sensitive host compounds

“…While increased solvent polarity has been described as important in effecting bathochromic shifts in azoaromatic compounds 15 we find that the concentration of the dissolved host compound is also a contributing factor. Thus for host 3 in DMF an increase in concentration results in a shift in absorption maximum as illustrated in Fig.…”

Effect of N‐Butyl‐N‐Methyl‐Morpholinium Bromide Ionic Liquid on the Conformation Stability of Human Serum Albumin

“…Fluorescence quenching mechanism was investigated to check the possible interactions of [Mor1,4][Br] with HSA to form a complex. The decrease in the fluorescence intensity of fluorophore occurs due to a variety of molecular interactions apart from the ground state complex formation and collisional quenching which are excited state reactions, energy transfer and rearrangement of molecules . The fluorescence quenching is classified as static and dynamic quenching.…”

Chromogenic guest-responsive host compounds which allow rapid guest screening

“…(There is also a substantial increase in the relative intensity of the band ascribed to the nAp* transition. 13 ) Effects of solvent polarity, 14 hydrogen bonding and loss of planarity 15 on the electronic transitions in azobenzenes 16 have been described and, in particular, Robin and Simpson have suggested mixing of the 'colour band' and nAp* transition of the azo group. 13 Clearly, changes in conjugation of the NLN and aromatic groups of the azobenzene core will affect the energy of these various transitions effecting changes in absorption maxima and hence in colour.…”