Terphenyl-Tricarboxylate Coordination Polymers: From\nHydrothermal Assembly to Structural Diversity and Catalytic Application

An\naromatic tricarboxylic acid building block, [1,1′:3′,1″-terphenyl]-4,4″,5′-tricarboxylic\nacid (H<sub>3</sub>tptca), was used as a versatile linker for assembling,\nunder hydrothermal conditions, a series of 12 new coordination polymers\n(CPs) in the presence of supporting <i>N</i>-donor ligands\nacting as mediators of crystallization. The obtained products were\nformulated as [Mn(μ-Htptca)(phen)<sub>2</sub>]<sub><i>n</i></sub>·<i>n</i>H<sub>2</sub>O (<b>1</b>), [Zn(μ-Htptca)(2,2′-bipy)(H<sub>2</sub>O)]<sub><i>n</i></sub>·<i>n</i>H<sub>2</sub>O (<b>2</b>), [Ni(μ<sub>3</sub>-Htptca)(μ-4,4′-bipy)]<sub><i>n</i></sub>·2<i>n</i>H<sub>2</sub>O (<b>3</b>), [Co(μ<sub>3</sub>-Htptca)(μ-bpe)]<sub><i>n</i></sub> (<b>4</b>), [M<sub>3</sub>(μ<sub>3</sub>-tptca)<sub>2</sub>(phen)<sub>3</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub>·2<i>n</i>H<sub>2</sub>O (M = Co (<b>5</b>), Zn (<b>6</b>)), [Co<sub>2</sub>(μ<sub>4</sub>-tptca)(μ-OH)(2,2′-bipy)<sub>2</sub>]<sub><i>n</i></sub> (<b>7</b>), [Zn<sub>3</sub>(μ<sub>3</sub>-tptca)<sub>2</sub>(2,2′-bipy)<sub>3</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub>·4<i>n</i>H<sub>2</sub>O (<b>8</b>), {[Cd(H<sub>2</sub>biim)<sub>3</sub>][Cd<sub>2</sub>(μ<sub>3</sub>-tptca)(μ<sub>5</sub>-tptca)]}<sub><i>n</i></sub> (<b>9</b>), [Co<sub>2</sub>(μ<sub>4</sub>-tptca)(μ-bpa)(μ<sub>3</sub>-OH)(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub>·<i>n</i>H<sub>2</sub>O (<b>10</b>), [Ni<sub>3</sub>(μ<sub>3</sub>-tptca)<sub>2</sub>(μ-bpa)<sub>3</sub>(H<sub>2</sub>O)<sub>4</sub>]<sub><i>n</i></sub>·5<i>n</i>H<sub>2</sub>O (<b>11</b>), and [Co<sub>2</sub>(μ<sub>4</sub>-tptca)(μ-bpb)(μ-OH)]<sub><i>n</i></sub> (<b>12</b>), wherein phen, 2,2′-bipy, 4,4′-bipy, bpe,\nH<sub>2</sub>biim, bpa, and bpb are 1,10-phenanthroline, 2,2′-\nand 4,4′-bipyridine, 1,2-di(4-pyridyl)ethane, 2,2′-biimidazole,\nbis(4-pyridyl)amine, and 1,4-bis(pyrid-4-yl)benzene, respectively.\nCrystal structures of CPs <b>1</b>–<b>12</b> reveal\na broad diversity metal–organic networks that range from 1D\nchains (<b>1</b>, <b>2</b>, <b>5</b>, <b>6</b>, and <b>8</b>) to 2D layers (<b>3</b>, <b>4</b>, <b>7</b>, <b>9</b>, and <b>11</b>) and 3D nets\n(<b>10</b> and <b>12</b>), including the examples of interpenetrated,\npolycatenated, and topologically unique architectures. Structural\nfeatures and catalytic properties of the obtained CPs were studied\nand discussed. In particular, a Zn(II) CP <b>8</b> acts as an\nefficient and recyclable heterogeneous catalyst for the mild cyanosilylation\nof benzaldehydes, leading to the formation of the corresponding cyanohydrin\nproducts in up to 99% yields. The obtained compounds widen a growing\nfamily of functional CPs driven by terphenyl-tricarboxylate linkers.