Abstract

Phosphotungstic acid (POM) was crystallized together with the neurotransmitter gamma-aminobutyric acid (GABA) in acidic medium to form [(HGABA)3PW12O40], compound 1. The latter would only crystalize in the presence of dopamine, while dopamine itself did not become a part of the complex, but crystallized separately as [(Hdopamine)2HPW12O40], compound 2, as previously reported. GABA interacts with POM via hydrogen bonding between the protonated amino group and a terminal oxygen on POM and also via protonated carboxylic acid group. Based on structural information from the crystal structures of 1 and 2 together with complementary studies using other catechols we attempted to provide molecular insight into the well-known structure-directing effect of dopamine. Strong hydrogen bonding between dopamine and POM, together with formation of "dopamine dimers" in the packed structure by interactions between the aromatic rings and intermolecular hydrogen bonding might be important factors for them in directing the self-assembly of polyoxometalates into complex hierarchal structures. Interaction between dopamine and GABA in solution was investigated by diffusion ordered spectrometry (DOSY) NMR in MilliQ-water and in 0.1 M HCl.

Keywords

POM; Metal oxide nanoparticle; Biomarker complex; GABA; Dopamine; Structure-directing agent

Published in

Inorganica Chimica Acta
2021, volume: 526, article number: 120547
Publisher: ELSEVIER SCIENCE SA

Authors' information