S. Yu. Zaitsev

Monolayers of the photosensitive benzodithia-15-crown-5 derivative.

Abstract The amphiphilic benzodithia-15-crown-5 styryl dye forms relatively stable insoluble monolayers on distilled water (collapse pressure is 34.5 mN m −1 ) and alkali metal cations (35.6–36.7 mN m −1 ) or heavy metal cations (24.2 mN m −1 for Ag + ) in the aqueous subphase. Three types of the dye monolayer structures depending on the subphase nature (water, alkali metal or heavy metal cations) have been distinguished from surface pressure-molecular area and surface potential-molecular area isotherms, as well as observed by Brewster angle microscopy (BAM). The ionoselective and photosensitive properties of the amphiphilic dye in monolayers have been studied in the presence of K + , Na + , Hg 2+ and Ag + cations in the aqueous subphases.

Monolayers of photosynthetic reaction centers of green and purple bacteria

Monolayers of the reaction centers isolated from the photosynthetic bacteria Chloroflexus aurantiacus, Rhodobacter sphaeroides and Rhodopseudomonas viridis were prepared and investigated. The monolayer characteristics of these proteins were analyzed to determine the optimum conditions for stable film preparations. Monolayers were transfered onto quartz and metal supports by the Langmuir-Schaefer method to provide multilayers of definite thickness. These films retain the optical and photoelectrical properties of the native photosynthetic membranes. The sign of the photopotential provides evidence for a different orientation of the reaction centers of Rb. sphaeroides compared to those of Rps. viridis.

Photosensitive and ionoselective properties of the amphipilic crown-ether dye in monolayers

Abstract Monolayers of the amphiphilic benzo-15-crown-5 styryl dye were prepared. Their ionoselective and photosensitive properties in the presence of K + or Na + cations in the aqueous subphases were investigated. The reversible changes of the reflection intensity (due to trans–cis–trans isomerization of the CC bound in dye molecule) can be observed only for complexes of the dye molecules in monolayers with cations from the aqueous subphase.

Monolayers of a novel ionoselective butadienyl dye

The novel amphiphilic benzodithia-18-crown-6 butadienyl dye (1) forms relatively stable insoluble monolayers on distilled water (collapse pressure of 41 mN/m) and on aqueous subphases containing alkali metal or heavy metal salts (collapse pressures in the range of 27-38 mN/m, respectively). The dye 1 monolayer organization depends on chromophore association and interactions (especially complex formation) with heavy and alkali metal ions as deduced from surface pressure-area and surface potential-area isotherms as well as reflection spectra and Brewster angle microscopy observations. Dye 1 undergoes specific interactions with Hg(2+) and Ag(+), respectively (formation of different complexes). Nonspecific interactions have been observed with other salts, such as KClO(4) or Pb(ClO(4))(2). Further, dye 1 monolayers on 1 mM Hg(ClO(4))(2) solution undergo reversible photoisomerization, in contrast to monolayers on water and other aqueous salt subphases.

Monolayers of an amphiphilic crown ether styryl dye.

Abstract The crown-ether styryl dye ( I ) was synthesized and its monolayers were prepared. The surface-active and optical properties of dye I were investigated. The surface pressure-molecular area and surface potential-molecular area isotherms for mixed monolayers of dye I and dipalmitoylphosphatidic acid at various aqueous salt subphases were measured.

Ionic selectivity of the surface-active derivatives of crown ethers in monolayers

Abstract The monolayer characteristics of the four surface-active derivatives of crown ethers (I–IV) with different ring size were studied under various conditions. The area per crown ether molecule in monolayers at the air-water interface increases with increasing size of the polyether ring, whereas the surface potentials remain almost the same. The areas per molecule are increasing significantly in the presence of various alkali metal cations in the aqueous subphase, especially in the case of K + . The highest absolute value was found for crown ether III with six oxygen atoms in the polyether ring. The surface potential values for all studied crown ethers decrease in the presence of the alkali metal cations. These effects can be explained as complex formation between crown ether in the monolayers and cations from the aqueous subphase. Using the recently developed Brewster angle microscopy, the differences of the monolayer morphology in the prescene and absence of the alkali metal cations in the aqueous subphase were monitored, providing additional evidence for complex formation.

Langmuir films of the novel anion-capped amphiphilic benzodithia-15-crown-5 dye.

Abstract The novel anion-capped amphiphilic benzodithia-15-crown-5 styryl dye forms relatively stable insoluble monolayers on distilled water (collapse pressure is approx. 35 mN/m) and on the aqueous subphases containing alkali metal cations (38 mN/m) or heavy metal cations (33 or 31 mN/m for Ag + or Hg 2+ ), respectively. Two types of the dye-cation complexes, depending on the nature of a particular cation in the aqueous subphase, have been distinguished by measuring surface pressure–molecular area and surface potential–molecular area isotherms, as well as observed by Brewster angle microscopy. The surface-active and spectroscopic properties of the amphiphilic dye in monolayers in the presence of K + , Na + , Ca 2+ , Mg 2+ , Ag + or Hg 2+ cations in the aqueous subphases have been studied.

Monolayer characteristics of bacterial photosynthetic reaction centers

Abstract Monolayers of the reaction center protein—pigment complexes, isolated from photosynthetic bacteria Chloroflexus aurantiacus, Rhodobacter sphaeroides (wild type and strain R-26) and Rhodopseudomonas viridis were prepared at air/aqueous solution interfaces. The surface pressure—area isotherms of these proteins were determined at various ionic strengths, pH and temperatures of the aqueous subphase to establish optimum conditions for stable film preparations: 10 mM phosphate buffer as the liquid subphase at pH 7.0 and 20°C. At these conditions the maximal collapse areas per reaction center complex from Rb. sphaeroides (both types have three protein subunits) and C. aurantiacus (two subunits) are in the range 35–45 nm2, while from R. viridis (four subunits) the area is about 90 nm2. Monolayers were transferred to roughened Ag electrodes for recording surface-enhanced resonance Raman scattering (SERRS) spectra at two excitation wavelengths (406.7 and 488.0 nm).

Polymer-surfactant interfacial layer of polystyrene particles modelling by monolayer technique

Abstract The mixed monolayers of polydimethylsiloxane (PDS), sodium alkylsylfonate (E30), styrene (St) and polystyrene (PSt) in various combinations have been studied. The results obtained for two and three-component systems give an evidence of the specific interaction (possible complex formation) of PDS and E30 (responsible for polymeric and surfactant stabiliser factors, respectively) at the interfaces. The four-component monolayers of PDS/PSt/St/E30 have only one liquid-expanded state that is similar to the three-component systems (PDS/St/E30 and PDS/PSt/E30) and in contrast to the two-component systems (PDS/St and PDS/PSt). Moreover, in the case of PDS/PSt/St/E30 (1.0 mass%) system the monolayer parameters are almost not depending on the concentration of PDS (in the range of 1–10 mass%) that suggested as the most adequate model of the interfacial layer of polystyrene latexes. The following optimal ratios of both stabilisers: PDS 1–2% and E30 about 1% (calculated to St) have been found.

A comparative study of the photosystem II membrane proteins with natural lipids in monolayers

Abstract Monolayers of the photosystem II core particles (PSIICP) and light-harvesting complexes from spinach and their mixtures with the following lipids: phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol and digalactosyldiglyceride (DGDG) were prepared and investigated. Strong interaction between PSIICP and DGDG was found as compared to other lipids. The standard protein bands for PSIICP were found by electrophoresis (SDS-PAGE) in all samples taken from the interface of the mixed lipid–protein monolayers, but not in those from the aqueous subphase. At surface pressure 40 mN/m, these protein bands remained the same only for mixed monolayers with DGDG. The damage of PSIICP by illumination in the lipid monolayers and strong binding of the remaining polypeptides with DGDG were shown.