CONFORMATION AND DYNAMICS IN A SOLUTION OF AN N-QUATERNIZED CINNAMIDE DERIVATIVE - A MOLECULE ACTIVE AS A UV FILTER

The dynamics and conformation of N,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 C-13 spin-lattice relaxation rates, non-selective and selective proton spin-lattice relaxation rates and H-1-(H-1) 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.