Solvent shifts in the NMR spectra of monomethoxyflavones a comparison of four solvent systems

Abstract

Nmr chemical shifts of methoxyl protons are reported for the eight monomethoxyflavones in four solvents: deuteriochloroform, benzene, dimethylsulfoxide, and pyridine. Benzene shift data are presented, and Δ CDCl 3Bz values interpreted on the basis of a preferential approach of benzene molecules near the positive end (hetero oxygen atom) of a large pyrone dipole. Pyridine shifts, relative to deuteriochloroform and dimethylsulfoxide, are reported. The Δ CDCl 3DMSO values for monomethoxyflavones indicate that only in 2′‐methoxyflavone is the shift value positive.

Benzotriazole derivatives palladium complex: Synthesis, characterization, antifungal and catalytic activity

“…Obviously, being very clear that there was a change in the working solvent, for free ligand was CDCl3 and in this case it is DMSO-d6, however, as reported in the literature [13], the difference of chemical shifts generated by the change between these solvents is very low enough to avoid, that the comparison between both spectra can be made. Even, it was propose, that the concentration affects even more the chemical displacements than the working solvents [14][15].…”