Syntheses, Crystal Structures, and NLO Properties of New Chiral Inorganic Chromophores for Second-Harmonic Generation.

A new chiral ligand (H(2)L) based on the condensation of diaminocyclohexane and 4-(diethylamino)salicylaldehyde is reported along with its nickel(II) and manganese(III) complexes. These compounds all crystallize in noncentrosymmetric space groups. Crystal data are as follows. For the ligand (C(28)H(40)N(4)O(2)): monoclinic, I2, a = 15.487(2) Å, b = 8.1988(6) Å, c = 20.958(3) Å, beta = 95.92(1) degrees, Z = 4. For the Ni(II)L complex: monoclinic, P2(1), a = 8.613(2) Å, b = 21.714(4) Å, c = 15.870(4) Å, beta = 91.02(2) degrees, Z = 4. For the Mn(III)LCl complex: orthorhombic, P2(1)2(1)2(1), a = 7.233(2) Å, b = 15.159(4) Å, c = 25.591(7) Å, Z = 4. The manganese derivative exhibits an efficiency 8 times that of urea in second-harmonic generation at 1.9 &mgr;m. INDO/SCI-SOS quantum-chemical calculations predict a sizable molecular nonlinear response and an enhancement of the nonlinearity after metal complexation.