Langmuir, Vol.10, No.11, 4157-4163, 1994
Incorporation of Metal-Complexes from the Subphase into Fatty-Acid Langmuir-Blodgett-Films
The technique of producing fatty acid Langmuir-Blodgett (LB) films incorporating metal complexes from the subphase (subphase films) by an ion-pairing mechanism is explored. Tris(4,4’,5,5’-tetramethyl-2,2’-bipyridine)ruthenium(II), [Ru(tm-bpy)(3)](2+), tris(1,10-phenanthroline)ruthenium(II), [Ru(phen)(3)](2+), and tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) [Ru(dpphen)(3)](2+), ionic complexes are dissolved in the subphase solutions. The pressure-area (pi-A) isotherms obtained for stearic acid on the surface of metal complex subphases indicate the formation of stable subphase LB films capable of being transferred onto a solid substrate. The absorption and the emission of the ruthenium complexes in the transferred films are red-shifted with respect to the acetonitrile solutions of the metal complexes. The metal complex molecules are located beneath the film layer and/or in the head group regions of the stearic acid molecules as indicated from the pi-A isotherms, the area per stearic acid unit calculated, and the shift in the absorption and the emission spectra. The surface LB films of the metal complex/stearic acid produced on the surface of the water subphase are compared with the subphase films and found to be equilibrating with the subphase films in a short time. The composition of the subphase films is also determined from HPLC and luminescence measurements.
Keywords:LB