Langmuir-Blodgett films based on known layered solids: Lanthanide(III) octadecylphosphonate LB films

Several lanthanide(III) octadecylphosphonate Langmuir-Blodgett (LB) films h ave been prepared and characterized. Films with La3+, Ce3+, Sm3+, and Gd3+, , formed one bilayer at a time using a Y-type deposition procedure that all ows the metal phosphonate continuous lattice network to crystallize during the upstroke of the film transfer. Comparison of the phosphonate IR stretch ing modes of the LB films to those of known model solids shows that each fi lm is an LB analogue of the powdered solid-state lanthanide butylphosphonat es of formula Ln(III)H(O3PC4H9)(2) that possess a two-dimensional ionic cov alent metal phosphonate network. X-ray photoelectron spectroscopy (XPS) sho ws that the P/Ln ratio in each of the transferred films is 2:1, which corre sponds to the stoichiometry in the known layered materials, and X-ray diffr action (XRD) shows that the films are layered each with a bilayer thickness of 51 +/- 1 Angstrom. The behavior of octadecylphosphonic acid Langmuir mo nolayers on subphases containing each metal ion is studied as a function of pH, and general procedures for the deposition of metal phosphonate continu ous lattice LB films are developed.