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

The dynamics and conformation ofN,N-dimethyl-N-[3-(4-methoxy-trans-cinnamoylamino)propyl]-N-n-dodecylammonium bromide (1) have been established in two solvents (CDCl3 and DMSO-d6) by the use of 13C spin–lattice relaxation rates, non-selective and selective proton spin–lattice relaxation rates and 1H–(1H) NOE experiments. The two solvents affect the conformation of the cinnamide moiety in different ways. This alters the anchor capacity of the moiety towards the alkyl chain and, as a consequence, the dynamics of 1 in CDCl3 and DMSO-d6 show understandable differences. However, the main mean conformations of 1 in both solvents are ‘linear’. The data do not allow the rationalization of the relationship between conformation and sunscreen efficiency.