Three Azamacrocycle-Based Coordination Complexes Bearing a New Triazine Derived Carboxylic Ligand <i>Via In Situ</i> Ligand Hydrolysis: The Trap of Resonance Structure

2016-04-01T06:27:01Z (GMT) by Hua Xia Xiaoyi Wang Yunhong Wang
<p>The <i>in situ</i> ligand hydrolysis reaction of 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine and macrocyclic complexes yields three coordination complexes bearing new triazine derived carboxylic ligands, namely, {(NiL<sub>1</sub>)(L<sub>0</sub>)·DMF}<sub>n</sub> (<b>1</b>), {(NiL<sub>2</sub>)(L<sub>0</sub>)·DMF·H<sub>2</sub>O}<sub>n</sub> (<b>2</b>), and [NiL<sub>3</sub>][(NiL<sub>3</sub>)(L<sub>0</sub>)<sub>2</sub>]·2H<sub>2</sub>O (<b>3</b>) (L<sub>o</sub> = 4-(6-Hydroxy-4-oxo-4,5-dihydro-[1,3,5]triazine-2-yloxy)-benzoic acid, L<sub>1</sub> = 1,4,8,11-tetraazacyclotetradecane, L<sub>2</sub> = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradeca and L<sub>3</sub> = 1,3,6,9,11,14-hexaazatricyclooctadecane). Single-crystal X-ray diffraction analyses reveal that <b>1</b> and <b>2</b> exhibit a one-dimensional (1D) chain structure, which is further connected into a three-dimensional (3D) supramolecular structure by hydrogen bonds. In complex <b>2</b>, π···π stacking interaction is observed. In contrast, <b>3</b> shows a ion-pair structure, which is connected into a 2D <b>4<sup>4</sup></b> hydrogen bonded supramolecular structure. The results indicate the subtle difference of azamacrocycle may lead to diverse structures. Importantly, in complexes <b>1–3</b>, the resonance structure is trapped in crystals 1–3.</p>