Conformation and dynamics in solution of an N-quaternarized benzophenone derivative: a molecule active as UV filter

The dynamics and conformation of N,N-dimethyl-N-|3-(benzoyl-4-phenoxy)|-N-n-dodecylammonium bromide, 1 , have been established in two solvents (CDCl 3 and DMSO-d 6 ) by the use of 13 C spin-lattice relaxation rates, non-selective and selective proton spin-lattice relaxation rates, and 1 H-{ 1 H} nuclear Overhauser enhancement (nOe) experiments. The data obtained are consistent with two main mean conformations for compound 1 : a "linear" conformation in CDCl 3 and a folded conformation in DMSO-d 6 where the alkyl chain forms a loop toward the aromatic moiety. Key words: UV filter, carbon and proton relaxation rates, nuclear Overhauser enhancement experiments, solvent dependent conformations.