Self-Encapsulation of [MII(phen)2(H2O)2]2+ (M = Co, Zn) in One-Dimensional Nanochannels of [MII(H2O)6(BTC)2]4− (M = Co, Cu, Mn): A High HQ/CAT Ratio Catalyst for Hydroxylation of Phenols

• Published in: Inorganic chemistry 2008-06, Vol.47 (11), p.4564-4569
• Main Authors: Bi, Jianhong, Kong, Lingtao, Huang, Zixiang, Liu, Jinhuai
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic7022049

Four novel three-dimensional (3D) microporous supramolecular compounds containing nanosized channels, namely, [Co(phen)2(H2O)2]2[Co(H2O)6]·2BTC·21.5H2O (1), [Co(phen)2(H2O)2]2[Cu(H2O)6]·2BTC·21.5H2O (2), [Co(phen)2(H2O)2]2[Mn(H2O)6]·2BTC·18H2O (3), and [Zn(phen)2(H2O)2]2[Mn(H2O)6]·2BTC·22.5H2O (4), were synthesized from 1,3,5-benzenetricarboxylate (BTC), 1,10-phenanthroline (phen), and the transition-metal salt(s) by self-assembly. Single-crystal X-ray structural analysis showed that the resulting 3D microporous supramolecular frameworks consist of a two-dimensional (2D) hydrogen-bonded host framework of [MII(H2O)6(BTC)2]4− (M = Co for 1, Cu for 2, Mn for 3, 4) with rectangular-shaped cavities containing [MII(phen)2(H2O)2]2+ (M = Co for 1−3, Zn for 4) guests. The guest complex is encapsulated in the 2D hydrogen-bonded host framework by hydrogen bonding and aromatic π−π stacking interactions, forming the 3D hydrogen-bonded framework. The catalytic activities of 1, 2, 3, and 4 were studied using hydroxylation of phenols with 30% aqueous H2O2 as a test reaction. The compounds displayed a good phenol conversion ratio and excellent channel selectivity in the hydroxylation reaction, with a maximum hydroquinone (HQ)/catechol (CAT) ratio of 3.9.