Group III quinaldates: synthesis, structure and photoluminescence

<p>The reactions of Al(III), Ga(III) and In(III) nitrates with 2-quinaldic acid (qaH) afforded [Al<sub>2</sub>(OH)<sub>2</sub>(qa)<sub>4</sub>]·2H<sub>2</sub>O (<b>1</b>), [Ga(qa)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]NO<sub>3</sub> (<b>2</b>) and [In(qa)<sub>2</sub>(NO<sub>3</sub>)(H<sub>2</sub>O)] (<b>3</b>), respectively, in high yields. The crystal structures of <b>1</b>, <b>2</b> and <b>3</b> have been determined by single-crystal X-ray crystallography. The structure of <b>1</b> features a di-hydroxo bridged [Al<sub>2</sub>(μ-OH)<sub>2</sub>]<sup>4+</sup> dimer in which each Al(III) is further ligated by two bidentate chelate qa<sup>−</sup> ligands. Complexes <b>2</b> and <b>3</b> are mononuclear with the M(III) ions in octahedral environments surrounded by two bidentate chelate qa<sup>−</sup> and two H<sub>2</sub>O in <b>2</b> or one H<sub>2</sub>O and a terminal NO<sub>3</sub><sup>−</sup> in <b>3</b>. Characteristic IR as well as thermal analysis and solid-state fluorescence are discussed.</p>