RESUMO
A series of novel resorcin-[4]arenes with extended pi systems have been synthesised and developed as potassium-selective transporters. Resorcin[4]arenes that feature crown ether moieties function as efficient carriers of K+ across bulk liquid membranes showing enhanced selectivity over the other alkali metal ions relative to a model system (benzo[15]crown-5). Incorporation of functionalities suitable for pore formation, in addition to an extra annulus of aromatic residues, gives molecules which have remarkable ion-channel-mimicking behaviour in a biological lipid bilayer with outstanding K+/Na+ selectivity.
Assuntos
Proteínas de Transporte/química , Canais de Potássio/química , Potássio/metabolismo , Resorcinóis/química , Indicadores e Reagentes , Bicamadas Lipídicas/química , Potenciais da Membrana , Conformação Molecular , Estrutura MolecularRESUMO
The new rhenium(I) bipyridine crown ether receptors 1-4 have been prepared and their ion pair recognition properties examined. The crystal structure of [1.KCl](2).2H(2)O demonstrates that potassium is coordinated by benzo-18-crown-6 and chloride is hydrogen bonded to the amide groups. Receptor 3 extracts solid KCl and KOAc into chloroform via ion pair complexation. NMR and emission titration studies with receptors 1-4 and KCl/KOAc show that cobound potassium enhances anion binding strength by electrostatic and conformational effects. Significant cooperative interactions are observed between the anion and cation sites for host 4 in CH(3)CN. This molecule coordinates potassium to form a 1:1 intramolecular sandwich complex, which preorganizes the host for acetate binding.
Assuntos
2,2'-Dipiridil/análogos & derivados , Éteres Cíclicos/química , Compostos Organometálicos/química , Cloreto de Potássio/química , Rênio/química , Acetatos/química , Ânions/química , Cátions Monovalentes/química , Cristalografia por Raios X , Éteres Cíclicos/síntese química , Espectroscopia de Ressonância Magnética , Compostos Organometálicos/síntese química , Espectrometria de Massas de Bombardeamento Rápido de ÁtomosRESUMO
Bis(tripyrrolyl) cryptands are prepared via a [2 + 3] Schiff base condensation of formyltripyrrolyls with diamines; an ethyl-spaced hexapyrrole cryptand is shown to bind strongly ethane-1,2-diamine and ethane-1,2-diol in chloroform solution.
RESUMO
Over the past year, several significant developments have been made in the field of anion binding. The fundamental principles of molecular recognition are increasingly being better understood, and of particular interest are reports of several synthetic anion receptors able to perform their task in complex natural media. Additionally, macroscopic devices such as anion specific electrodes and membranes based on a molecular recognition approach are now being made.
