Monolayers and Langmuir-Blodgett films of palladium-mediated multiporphyrin arrays with different central ions

Pd-mediated multi-metalloporphyrin arrays have been constructed at the air–water interface. Monolayer behaviors and spectroscopic properties of the arrays closely related to the central ions of metalloporphyrins. It was found that, although oxo[5,10,15,20-tetra(4-pyridyl)porphinato]titanium (TiOTPyP) was unable to form condensed monolayer on the pure water surface, it could be stabilized on the K₂PdCl₄ subphase surface due to the formation of Pd-TiOTPyP multiporphyrin arrays. Among the three kinds of multiporphyrin arrays investigated, zinc 5,10,15,20-tetra(4-pyridyl)porphine (ZnTPyP) showed largest average molecular area and lowest collapsed surface pressure on the 0.3–0.5 mmol/l K₂PdCl₄ subphase surfaces. Compared with the absorption spectra in solutions, porphyrin Soret band red shifted in the monolayers and Langmuir-Blodgett (LB) films of multiporphyrin arrays, the extent of this red shift closely related to the central ions of porphyrins. Moreover, fluorescence emissions were partly quenched in the LB films of multi-metalloporphyrin arrays.