Surface Pressure and Surface Potential Isotherms of Ytterbium Bisphthalocyanine Langmuir Monolayers

Abstract

A systematic study is reported on the monolayer characteristics of ytterbium bisphthalocyanine (YbPc2) at the air−water interface, using surface pressure and surface potential isotherms. The influence of various experimental parameters was analyzed, including compression speed, spreading volume, position of the pressure sensor, and subphase temperature. The area per molecule decreased with increasing spreading volumes. Interestingly, the position of the Wilhelmy plate affected the pressure−area isotherms, which does not occur for traditional aliphatic compounds. No significant influence from the subphase temperature was detected. Upon varying the compression speed, the surface potential curve and the collapse pressure were affected, even though the area per molecule remained practically the same. When these monolayers with distinct dipole moments were transferred onto a gold-coated glass substrate, the resulting multilayer LB films exhibited the same surface potential, probably due to molecular rearrangement upon transfer.

Deposition of Extended Ordered Ultrathin Films of Au38(SC2H4Ph)24 Nanocluster using Langmuir–Blodgett Technique

“…There is a large number of factors present in this complex system which can typically be associated with an increase in slope of the surface pressure isotherm. They include: changes in the orientation of the molecule, [ 39 ] shifts in phase of the lattice (degree of interdigitation between ligands), [ 18 ] and formation of multilayers of nonamphiphilic particles. [ 40 ] The overall transition from gaseous to condensed state is presumably a convolution of these effects.…”

“…This is consistent with many LB studies of nonamphiphilic molecules that do not exhibit the stabilizing effect of hydrophilic and hydrophobic parts of the molecule directing the orientation on the water surface. [ 39,41 ] Weak van der Waals interactions stemming from the small size of the cluster can lead to facile buckling upward of the molecules and, hence, their build up in three dimensions.…”

Phase separation in mixed monolayers of arachidic acid and a phthalocyanine of zinc

“…Pthalocyanine molecules have a strong system which can be polarized, and it is responsible for phthalocyanine films presenting higher surface potentials, as has been observed in Langmuir films of several phthalocyanines [41][42][43]. UV-Vis spectra in figure 7 show that LB films present a decrease in the Q-band (red zone of the spectra) in respect to the Soret-band (near-UV zone) when compared with the spectra in solution, which has also been observed in others Pc [36,44].…”

Formation and characterization of europium bisphthalocyanine nanowires by electrophoretic deposition

“…The typical methods used to fabricate bisphthalocyanine films include vacuum deposition, Langmuir-Blodgett (LB) technique and molecular beam epitaxy, etc. [14][15][16]. Compared with the mentioned fabrication methods for Pcs films, which are accomplished at high cost and long time because of their poor solubility in aqueous and organic solvents, the electrophoretic deposition (EPD) technique proved to be an alternative way with low cost and short time.…”