ABSTRACT
Upper rim phosphonic acid functionalized calix[4]arene affects selective transport of multiple molecular payloads through a liquid membrane. The secret is in the attachment of a receptor-complementary handle to the payload. We find that the trimethylammonium ethylene group present in choline is one of several general handles for the transport of drug and drug-like species. Herein we compare the effect of handle variation against the transport of serotonin and dopamine. We find that several ionizable amine termini handles are sufficient for transport and identify two ideal candidates. Their performance is significantly enhanced in HEPES buffered solutions. This inquiry completes a series of 3 studies aimed at optimization of this strategy. In completion a new approach towards synthetic receptor mediated selective small molecule transport has emerged; future work in vesicular and cellular systems will follow.
Subject(s)
Calixarenes/pharmacology , Choline/metabolism , Dopamine/metabolism , Neurotransmitter Agents/pharmacology , Serotonin/metabolism , Biological Transport/drug effects , Calixarenes/chemical synthesis , Calixarenes/chemistry , Choline/chemistry , Dose-Response Relationship, Drug , Molecular Structure , Neurotransmitter Agents/chemical synthesis , Neurotransmitter Agents/chemistry , Structure-Activity RelationshipABSTRACT
Calix[6]arene hexacarboxylic acid binds instantly and with low symmetry to Pb, Sr and Ba. Later a highly symmetric up-down alternating conformation emerges. The solution structures are identical to their p-tert-butylcalix[6]arene hexacarboxylic acid counterparts. With either receptor an octahedral cage is formed around the metal. The transformation from low to high symmetry however proceeds at significantly faster rates for the de-t-butylated host.
