Comparative conformational and dynamical study of some N-quaternarized UV filters: structure–activity relationships

Abstract

A comparative conformational and dynamical study of a series of structurally related molecules with UV-filtering properties, i.e. N,N-dimethyl-N-[2-(4-benzoyl-2-hydroxyphenoxy)ethyl]-N-dodecyl ammonium bromide 2, N,N-dimethyl-N-[6-(4-benzoylphenoxy)hexyl]-N-dodecyl ammonium bromide 3 and N,N-dimethyl-N-[3-(salicyloylamino)propyl]-N-dodecyl ammonium bromide 5, has been performed in CDCl3 and [2H6] DMSO solutions. The main conformers of 2 and 3 (extensively folded conformations) and 5 (‘linear’ conformations) were determined by means of selective spin-lattice proton relaxation rates, carbon spin-lattice relaxation rates and 1D nuclear Overhauser effects. On the basis of these results a possible correlation between conformation and antibacterial activity is discussed.