Investigations of preferential solvation on 1,4-dimethoxy-3-methyl anthracene-9,10-dione

Optical Properties of Some Fluorinated Poly(1,3,4-Oxadiazole-Ether)s in Homogeneous and Heterogeneous Media. Changes Induced by SnO2, NiO and SnO2/NiO Mixed-Oxide Nanoparticles

Optical characteristics of some fluorinated poly(1,3,4-oxadiazole-ether)s in presence of SnO2, NiO and SnO2/NiO mixed-oxide nanoparticles (NPs) was investigated. The interactions between polymers and metal oxide NPs were studied by steady-state UV-Vis absorption and fluorescence spectroscopy techniques. The absorption and fluorescence signals of all investigated polymers was modified by presence of both pure and mixed-oxide nanoparticles. The moderate values of Stern-Volmer quenching constant and non-linear trend of Scott plot indicate the less affinity between metal oxide NPs and polymers. The solvation behavior of some fluorinated poly(1,3,4-oxadiazole-ether)s in chloroform-N,N-dimethylformamide and N,N-dimethylformamide-dimethylsulfoxide mixtures was discussed.

Solvent effects on the photophysical properties of poly[1,4-dihydroxyanthraquinoneimine-1,3-bis(phenylene-ester-methylene)tetramethyldisiloxane]

Absorption and fluorescence spectra of a polyquinoneimine, PQI, built on 1,4-dihydroxyanthraquinone and a siloxane diamine, 1,3-bis(amino-phenylene-ester-methylene)tetramethyldisiloxane, have been investigated in solvents of different polarities. The effect of solvents on the spectral properties was investigated using Lippert-Mataga and Bakhshiev polarity functions and Catalán's multiple linear regression approach. Absorption and fluorescence spectra in studied solvents exhibit hypsochromic and bathochromic shifts, respectively. The polarity of the solvent was the main parameter which changes the spectral properties of PQI. Also, the binary mixtures of chloroform with methanol and dimethyl sulfoxide were used to analyze the intermolecular interactions and preferential solvation. The preferential solvation parameters (local mole fraction (X₂(L)), excess function (δs₂) and preferential solvation constant (KPS)) were calculated from spectral data and discussed as a function of cosolvent content. The values of quantum yield, decreased linearly with increasing solvent polarity (for non-polar and polar solvents).

Preferential solvation of thiophene and furan-2-carboxaldehyde phenylhydrazone derivatives in DMSO-water and DMSO-n-octanol mixtures

The preferential solvation of thiophene- and furan-2-carboxaldehyde phenylhydrazone derivatives in DMSO-water and DMSO-n-octanol mixtures has been studied using visible absorption spectroscopy with a previous characterization of the electronic transitions by Time-Dependent Density Functional Theory (TDDFT) and solvatochromic study in several solvents with different hydrogen-bond donor capacity. The results indicate that the phenylhydrazones are preferentially solvated by clusters of DMSO-water existing in the solvent mixture and the dielectric enrichment as preferential solvation mechanism was discarded. A relation between local DMSO concentration with nitro groups and the electronegativity of the heteroatom of the five-membered ring was found. For DMSO-1-octanol mixtures, the results showed no preferential solvation.