Properties of mixed monolayer and LB films of chiral amino acid porphyrin

Mixed monolayers of a new chiral amino acid porphyrin (Py) and arachidic ac id (AA) at the air/water interface were studied The diagrams obtained by pl otting the mean area per molecule as a function of molar fraction of Py sho wed positive deviations from ideal conditions at Low surface pressure (pi) such as pi = 5 and 15 mN m(-1) and showed ideal miscible behavior at high s urface pressures, such as pi = 25 mN m(-1). Vertical uniformity of the mixe d LB films was demonstrated by UV-visible and fluorescence spectra. Aggrega tes were present when the mixed him was transferred at various surface pres sures and at different molar ratios of Py and AA. When the molar ratio of P y was increased from 0.05 to 1.00, the absorption peak of the Soret band ba thochromically shifted ca. 5.3 nm. When the deposited pressure is increased from 5 to 30 mN m(-1), the absorption peak of Soret band of 1:4 Py-AA mixe d LB film bathochromically shifted ca. 3.7 nm, and the absorbance increased linearly. Low angle X-ray diffraction results showed that the mixed LB fil ms had a periodic layer structure with a layer spacing of ca. 5.5 nm. (C) 2 000 Elsevier Science B.V. All lights reserved.