Novel 2D and 3D Indium Metal-Organic Frameworks:  Topology and Catalytic Properties

Four novel metal-organic frameworks (MOFs) In(BDC) 1.5 (bipy) ( 1 ), In 2 (OH) 2 (BDC) 2 (phen) 2 ( 2 ), In(BTC)(H 2 O)(bipy) ( 3 ), and In(BTC)(H 2 O)(phen) ( 4 ) (BDC = 1,4-benzendicarboxylic acid, BTC = 1,3,5-benzenetricarboxylic acid, bipy = 2,2‘-bipyridyl, phen = o -phenantroline) were synthesized and their structures were determined by X-ray single-crystal diffraction. Structurally speaking we can conclude that while the metal/connector/chelate rate is 1:1:1, the introduction of a chelate ligand, such as bipy or phen, blocks the possibility of connections in one direction, inducting the formation of 2D structures. In the case of compound 1, the extra one-half of BDC ligand per indium favors the eight coordination of the metal and drives the formation of a catenated 3D structure. Topological studies on the four compounds show one inclined catenation of hexagonal layers for 1 and three interdigitated layered structures with 2D topologies of type (4 4 ), (6 3 ), and (4.8 2 ) for 2, 3, and 4 compounds, respectively. Three of the new In compounds are active and selective acid catalyst in acetalization of aldehydes.