thiourea and tris(2-aminoethyl)amine

Thioureas are well-known structural motifs in supramolecular anion recognition. Their conformational preferences are typically characterized by detailed NMR spectroscopy and crystallography, which are often complemented with computational results from geometry optimizations. Herein we investigate a chiral tris(thiourea) based on tris(2-aminoethyl)amine, which acts as an anion receptor for chloride and hydrogen sulfate. We show that a detailed NMR analysis led to a rather ambiguous picture of the conformational preferences of 1 in its complexes. The computational results were found to depend heavily on the selected computational level (functionals with or without dispersion corrections) and relative energies (zero-point corrected

Topics: Amines; Anions; Circular Dichroism; Ethylenediamines; Thiourea

The interaction of six tripodal synthetic chloride transmembrane transporters with a POPC bilayer was investigated by means of molecular dynamics simulations using the general Amber force field (GAFF) for the transporters and the LIPID11 force field for phospholipids. These transporters are structurally simple molecules, based on the tris(2-aminoethyl)amine scaffold, containing three thiourea binding units coupled with three n-butyl (1), phenyl (2), fluorophenyl (3), pentafluorophenyl (4), trifluoromethylphenyl (5), or bis(trifluoromethyl)phenyl (6) substituents. The passive diffusion of 1-6⊃ Cl(-) was evaluated with the complexes initially positioned either in the water phase or inside the bilayer. In the first scenario the chloride is released in the water solution before the synthetic molecules achieve the water-lipid interface and permeate the membrane. In the latter one, only when the chloride complex reaches the interface is the anion released to the water phase, with the transporter losing the initial ggg tripodal shape. Independently of the transporter used in the membrane system, the bilayer structure is preserved and the synthetic molecules interact with the POPC molecules at the phosphate headgroup level, via N-H···O hydrogen bonds. Overall, the molecular dynamics simulations' results indicate that the small tripodal molecules in this series have a low impact on the bilayer and are able to diffuse with chloride inside the lipid environment. Indeed, these are essential conditions for these molecules to promote the transmembrane transport as anion carriers, in agreement with experimental efflux data.

Topics: Chlorides; Diffusion; Ethylenediamines; Lipid Bilayers; Models, Molecular; Molecular Dynamics Simulation; Permeability; Phosphatidylcholines; Thiourea

Easy-to-make tripodal tris-thiourea receptors based upon tris(2-aminoethyl)amine are capable of chloride/bicarbonate transport and as such represent a new class of bicarbonate transport agent.

Topics: Bicarbonates; Chloride-Bicarbonate Antiporters; Chlorides; Crystallography, X-Ray; Ethylenediamines; Membranes, Artificial; Models, Molecular; Molecular Structure; Stereoisomerism; Thiourea