Issue 43, 2021

Pair distribution function and 71Ga NMR study of aqueous Ga3+ complexes

Abstract

The atomic structures, and thereby the coordination chemistry, of metal ions in aqueous solution represent a cornerstone of chemistry, since they provide first steps in rationalizing generally observed chemical information. However, accurate structural information about metal ion solution species is often surprisingly scarce. Here, the atomic structures of Ga3+ ion complexes were determined directly in aqueous solutions across a wide range of pH, counter anions and concentrations by X-ray pair distribution function analysis and 71Ga NMR. At low pH (<2) octahedrally coordinated gallium dominates as either monomers with a high degree of solvent ordering or as Ga-dimers. At slightly higher pH (pH ≈ 2–3) a polyoxogallate structure is identified as either Ga30 or Ga32 in contradiction with the previously proposed Ga13 Keggin structures. At neutral and slightly higher pH nanosized GaOOH particles form, whereas for pH > 12 tetrahedrally coordinated gallium ions surrounded by ordered solvent are observed. The effects of varying either the concentration or counter anion were minimal. The present study provides the first comprehensive structural exploration of the aqueous chemistry of Ga3+ ions with atomic resolution, which is relevant for both semiconductor fabrication and medical applications.

Graphical abstract: Pair distribution function and 71Ga NMR study of aqueous Ga3+ complexes

Supplementary files

Article information

Article type
Edge Article
Submitted
17 Sep 2021
Accepted
14 Okt 2021
First published
14 Okt 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2021,12, 14420-14431

Pair distribution function and 71Ga NMR study of aqueous Ga3+ complexes

I. G. Nielsen, S. Sommer, A. Dippel, J. Skibsted and B. B. Iversen, Chem. Sci., 2021, 12, 14420 DOI: 10.1039/D1SC05190C

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