Synthesis, characterization, and second-harmonic: generation studies of rhenium(I) surfactant complexes in Langmuir-Blodgett films

A series of rhenium(I) surfactant complexes of general formula fac-[Re(CO)( 3)(bpy)(L)]PF6 (bpy = 2,2'-bipyridine, L = 4-(4'-octadecyloxyphenylazo)pyri dine (L1), 4-(4'-octadecyloxyphenylstilbazole)pyridine (L2), 4-(4'-octadecy loxyphenylethynyl)pyridine (L3)) were synthesized and characterized, and th eir photophysical and photochemical properties studied. The X-ray crystal s tructure of the complex fac-[Re(CO)(3)(bpy)(L1)]PF6 has been determined. Th e formation and optical properties of these complexes in Langmuir-Blodgett (LB) films were studied by surface pressure-area (pi-A) isotherms and UV-vi sible and luminescence spectroscopy. Their second-harmonic generation (SHG) behavior has also been investigated. These Re(I) surfactant complexes were shown to exhibit first-order hyperpolarizabilities comparable to, and in s ome cases slightly higher than, those of their organic analogues.