Fascinating Role of the Number of f Electrons in Dipolar and Octupolar Contributions to Quadratic Hyperpolarizability of Trinuclear Lanthanides-Biscopper Schiff Base Complexes.

The trinuclear [Ln(NO3)3 (CuL) 2] complexes (Ln = La, Ce, Sm, Eu and Er, L = N,N'-l,3-propylen-bis(salicylideniminato) have been investigated by a combination of HLS and EFISH techniques to evaluate both the dipolar and octupolar contributions to their significant quadratic hyperpolarizability and to confirm that f electrons may tune their second-order NLO response, hi the complexes investigated, the major contribution to the total quadratic hyperpolarizability is largely controlled by the octupolar contribution, but the values of both βEFISH and ǁ β1=1ǁ, that is the dipolar part, are significantly influenced by the number of f electrons, confirming that the unexpected polarizable character of f electrons may be the origin of such fascinating evidence. [ABSTRACT FROM AUTHOR]