Systematic pH-specific synthesis and structure transformations in binary-ternary In(III) assemblies with hydroxycarboxylic DPOT and aliphatic-aromatic chelators

Abstract

Driven by the need to generate hybrid In(III)-(O,N) luminescent materials containing appropriately configured organic ligands, binary-ternary In(III) metal-organic systems involving the multidentate organic ligand DPOT, ethylenediamine (en) and phenanthroline (phen) were investigated under pH-specific conditions. The arisen materials [In2(C11H13N2O9)2](CH6N3)4·7H2O(1), [In3(C11H13N2O9)2(C2H8N2)2](C2H9N2)·4H2O(2), [In2(C11H13N2O9)2](CH6N3)6(Cl)2·6H2O(3), and [In2(C11H13N2O9)(C12H8N2)2(Cl)(H2O)]·7.5H2O(4) were characterized by analytical, spectroscopic (FT-IR, 13C-MAS NMR, luminescence) techniques, TGA and X-ray crystallography. The binary materials 1 and 3 exhibit dinuclear alkoxido-bridged In2O2 cores, with the fully-deprotonated organic ligand spanning both centers. Introduction of bidentate ethylenediamine leads to ternary trinuclear species 2, whereas phen introduction in 4 leads to a dinuclear asymmetric assembly, incorporating a chloride ion and a water molecule. Chemical transformations among 1–4 provide mechanistic insight into the nature of chelators, dictating nuclearity, coordination, composition and lattice-specific luminescence. The collective physicochemical properties in 1–4 present well-defined 1D-3D structural architecture-dimensionality and spectroscopic property correlations, pointing out criteria based on which synthon design, custom architecture and photoactivity are interwoven into the future development of In(III)-containing metal-organic hybrid materials.