Ernesto Abel

Aggregate formation from 3-alkylindoles: amphiphilicmodels for interfacial helix anchoring groups

Indole can function as an amphiphile headgroup, but the counter-intuitive observation that 3-substituted indoles form less stable aggregates than the N-substituted isomers has been addressed by use of a Langmuir–Blodgett trough.

A Redox-switchable Molecular Receptor Based on Anthraquinone

Abstract The reaction of two equivalents each of bisphenol A with 1,5-dichloroanthraquinone in the presence of base leads to a molecular box designed to be electroactive. The compound is fully characterized, it exhibits reversible redox behavior, and its solid state structure has been obtained. Two molecules of toluene are present in the crystal lattice but these are not located within the receptors cavity. Evidence for an interaction of ferrocene (guest) with a precursor to the molecular box is described.

N,N-Didansyl-4,13-diaza-18-Crown-6: A Fluorescence-sensitive, Weakly Complexing Macrocycle Used to Probe the Phospholipid Vesicle Environment

N, N-Didansyl-4, 13-diaza-18-crownh-a6s been prepared and characterized by standard chemical techniques. The fluorescence emission of the dansyl sidearms are sensitive to the environment and the macrocycle has been used to probe the interior of a phospholipid bilayer. An experiment to probe the environment experienced by metal cation complexes of this macrocycle failed, apparently due to its extremely low cation binding strength. This macrocycle was also ineffective in transporting Na+ through a bulk CHC13 membrane. A solid state structure of the free macrocycle suggests why binding is so poor for this compound.

A tris(macrocycle) that exhibits H-bond-induced blockage of the cation channel faction in a phospholipid bilayer

An indole-terminated tris(macrocyclic) compound, designed to be a channel-former, is an effective carrier in bluk membranes but fails to function in a lipid bilayer owing to hydrogen bond formation which blocks the channel.

Control of vesicle formation by chemical switching

Abstract The formation and collapse of liposomes is controlled by the existing balance between polar headgroup and hydrophobic tail. Alteration of the headgroups charge state can be controlled, for example by redox-switching, which in turn permits regulation of aggregate formation.

Unusually long open times, determined by planar bilayer conductances studies, for a synthetic tris(macrocycle) that functions as a transmembrane channel in a phospholipid bilayer

Two tris(macrocycle)s are shown by bilayer clamp studies to function as cation channels in a phospholipid bilayer; one of the pair of closely related compounds shows unusually long open times compared either to the other tris(macrocycle) or to natural channel-forming proteins.

Alcohol oxidation and aldol condensation during base-catalyzed reaction of primary alcohols with 1-chloroanthraquinone

Abstract When chloroanthraquinone is treated with primary alcohols under basic conditions, the notoriously low yields observed for substitution result in part from oxidation of the alcohol followed by aldol condensation.

Tris(Macrocycles) as Models for Transmembrane, Cation-Conducting Channels

All living systems are bounded by such structures as cell walls or membranes which protect them from their environment and which prevent their interior contents from being lost. Cells cannot be completely isolated from their environment because nutrients must be acquired and waste products must be expelled. The flow of such species as cations through membranes is controlled by cation-conducting, transmembrane proteins. These proteins are currently receiving enormous attention from the biochemical, biophysical, and molecular biological communities.5 In addition to the study of naturally occurring protein channels, a number of chemical research groups have designed, synthesized, and studied model channel systems.6

A novel oxazine from the condensation of chloroanthraquinone and t-butyl L-prolinate

A new, fused-ring oxazine was synthesized in a one-pot condensation of L-proline t-butyl ester and 1-chloroanthraquinone. The compound crystallized in space group P212121 with cell parameters a = 10.1820(10) Å, b = 15.213(2) Å, c = 18.649(2) Å, and Z = 4. The absolute structure of the compound was obtained by the Flack parameter.