Surface and Aggregation Behavior of Aqueous Solutions of Ru(II) Metallosurfactants. 3. Effect of Chain Number and Orientation on the Structure of Adsorbed Films of [Ru(bipy)₂(bipy‘)]Cl₂ Complexes

Abstract

The surface behavior of a range of surfactant [Ru(bipy)(2)(p,p'-dialkyl-2,2'-bipy)]Cl(2) complexes, which we express as Ru(q)(p)C(n) where n is the alkyl chain length, p refers to the substitution position on the bipyridine ligand (=4 or 5), and q (=1 or 2) is the number of substituted alkyl chains, has been examined using neutron reflectometry. The adsorption of the single-chain Ru(1)(4)C(19) and Ru(1)(5)C(19) surfactants is strongly time-dependent, taking in excess of 10 h to form an equilibrium film. It is suggested that the slow adsorption rate is related to the alkyl chain length rather than the low monomer concentration present in the solutions. At concentrations below the critical micelle concentration (cmc) of Ru(1)(4)C(19), the film of Ru(1)(5)C(19) is denser than that of Ru(1)(4)C(19) at comparable concentration, consistent with the mass densities of the bulk solids, whereas at concentrations close to and greater than this cmc the converse pertains. Close to the cmc, the adsorbed films possess an average area per molecule significantly less than the nominal headgroup area of the surfactants (approximately 30 angstroms(2) compared with approximately 100 angstroms(2)). This fact together with consideration of the thickness and density of the adsorbed films leads to the conjecture that surface aggregates may be the adsorbing units. The adsorption of the double-chain surfactant Ru(1)(p)C(19), in contrast to the behavior of the Ru(1)(p)C(19) surfactants, is weak and independent of time. This behavior is attributed to the alkyl chain orientation. The adsorption behavior of a racemic mixture of the Delta and Lambda isomers of Ru(2)(4)C(19) has been compared with that of the Delta isomer. It is found that the film of racemic material is more closely packed than that of the resolved complex.

Metallo-Liposomes of Ruthenium Used as Promising Vectors of Genetic Material

“…The syntheses of the ruthenium complexes [Ru(2,2 -bipy) 2 (4,4 -(C 11 H 23 ) 2 -2,2 -bipy)]Cl 2 (RuC11C11, see Figure 2A) and [Ru(2,2 -bipy) 2 (4,4 -(C 19 H 39 ) 2 -2,2 -bipy)]Cl 2 (RuC19C19, see Figure 2B) were previously described [37,38]. IR and NMR spectra and elemental analysis (C, H, N) were carried out for the characterization of these compounds.…”

Studies on DNA Binding of a Double-chain Surfactant Cobalt(III) Complex Containing 2,2′-Bipyridine Ligand

“…Surfactant-metal complexes represent a new class of materials in which the polar head group of the surfactant molecule contains a metal complex portion as an integral structural component. There are only a few reports [14][15][16] on the synthesis, isolation and characterization of surfactant transition metal complexes, whereas there are numerous reports on the formation and study of such surfactants in solution without isolation. We were interested in the synthesis and micelle forming properties of cobalt(III) complexes containing lipophilic ligands [17,18].…”

Surfactant–cobalt(III) complexes: Synthesis, critical micelle concentration (CMC) determination, DNA binding, antimicrobial and cytotoxicity studies

“…Metallosurfactant complexes represent a new class of materials in which the polar headgroup of the surfactant molecule contains a metal complex portion as an integral structural component. There are only a few reports [10][11][12] on the synthesis, isolation and characterization of surfactant transition metal complexes, whereas there are numerous reports on the formation and study of such surfactants in solution without isolation. We have been interested in the synthesis and micelle forming properties of cobalt(III) complexes containing lipophilic ligands [13][14][15].…”