Triple Fluorescence of Substituted Benzanilides in Solution and in Solid States

The competitive triple fluorescence of benzanilide is studied by steady-state fluorescence investigations in dependence on the solvent polarity and the para-substitution of the aniline core as well as by comparison with the fluorescence behavior of 4-methoxy-N-methylbenzanilide. The normal fluorescence of benzanilide S₁(LE) S₀ appears at _max = 345 nm, whereas a superposition of proton transfer (PT) fluorescence S₁(PT) S₀(PT) and intramolecular charge transfer (ICT) flu-orescence S₁(ICT) S₀(FC) is responsible for the long-wavelength fluorescence in the 500-nm region. Different possibilities for the formation of the PT and ICT states are discussed. Investigations of the fluorescence behavior of benzanilides both in solution and as crystals in dependence on the para-substitution of the benzanilide moiety support the PT/ICT model.     

Joint QSAR Analysis Using the Free-Wilson Approach and Quantum Chemical Parameters

Abstract

A new quantitative structure-activity relationship (QSAR) technique combining the Free-Wilson method and constructed quantum chemical parameters was used to simulate the aqueous solubility (S _w), 1-octanol/water partition coefficient (K _ow) of 14 new synthesized benzanilide derivatives and their 96 h acute toxicity (EC₅₀) to Daphnia magna. The mode of action of the 14 selected compounds to Daphnia magna was shown to be a complex process involving a physical partition stage and a biochemical reaction stage. The results also indicated that the joint (QSAR) analysis was much effective than the original Free-Wilson method and Hansch method not only in predicting properties/toxicity, but also in investigating the mode of action of chemicals.     

A Study of cis - trans Isomerism of Benzalide and Thiobenzanilide

The conformations of the benzanlide and thiobenzanilide are studied using IR spectral data and Extended Huckel MO calculations. The results indicate that the benzanilide in CCl₄ dilute solution exist only in a trans-conformation, while the thiobenzanilide exist in a cis-trans equilibrium. The observed relative stabilities of the cis-thiobenzanilide can be explained on the basis of the calculated torsional barriers around the thiocarbonyl-nitrogen bond.     

Unusual spectral shifts on fast violet-B and benzanilide: Effect of solvents, pH and β-cyclodextin

The absorption and fluorescence spectra of fast violet-B (FVB) and benzanilide (BA) have been analysed in different solvents, pH and β-cyclodextrin. The inclusion complex of FVB with β-CD is investigated by UV–visible, fluorimetry, AM 1, FTIR and SEM. The absorption maximum of FVB (anilino substitution) is red shifted than that of BA, but the benzoyl substitution hardly changed the ground state structure of BA. Compared to BA, the emission maxima of FVB largely blue shifted in cyclohexane and aprotic solvents, but red shifted in protic solvents and the longer wavelength maxima in FVB is due to the intramolecular charge transfer (TICT). In BA, the normal emission originates from a locally excited state and the longer wavelength band due to intramolecular proton transfer in non-polar/aprotic solvents and in protic solvents it is due to TICT state. β-CD studies reveal that, FVB forms 1:2 complex from 1:1 complex and BA forms 1:2 complex with β-CD.