Acid directed in situ oxidation and decarboxylation of 4,4 %26apos;,6,6 %26apos;-tetra- methyl-2,2 %26apos;-bipyridine: Synthesis and structural characterisation of 4,4 %26apos;,6-tri-carboxy-2,2 %26apos;-bipyridine and its copper(II) coordination polymer

作者：Kelly Niamh R; Goetz Sandrine; Hawes Chris S; Kruger Paul E^*

来源：Inorganica Chimica Acta, 2013, 403: 102-109.

DOI：10.1016/j.ica.2012.12.033

• Coordination polymer
• 4,4 %26apos
• ,6,6 %26apos
• -Tetracarboxy-2,2 %26apos
• -bipyridine
• Decarboxylation
• Crystal engineering
• Supramolecular chemistry
• 2,2 %26apos
• -Bipyridine
• MOF
• In situ ligand synthesia

The reaction of either 4,4%26apos;,6,6%26apos;-tetramethyl-2,2%26apos;-bipyridine, L, or 4,4%26apos;,6,6%26apos;-tetracarboxy-2,2%26apos;-bipyridine, H4L, with Cu(OAc)(2)center dot H2O under acidic hydrothermal conditions (50:1 H2O/HNO3; 160 degrees C) led to the formation of crystalline {[Cu(HL%26apos;)(H2O)]center dot H2O}, 1, which was structurally characterised to identify H3L%26apos; as 4,4%26apos;,6-tricarboxy-2,2%26apos;-bipyridine. Clearly, in situ mono-decarboxylation of a tetracarboxylic acid ligand gave the tricarboxy-analogue, H3L%26apos;. The structure of 1 consists of a 1D coordination polymer that cross-links through hydrogen-bonding between adjacent carboxylic acid and carboxylate groups, as well as through an aqua ligand and lattice water molecule, to form a densely interconnected 3D network. Regioselective mono-decarboxylation of L or H4L at the 6%26apos;-carboxylic acid position may also be affected by heating L or H4L in acidic solution under hydrothermal conditions (2:1 H2O/HNO3; 160 degrees C) to yield crystalline 4,4%26apos;,6%26apos;-tricarboxy-2,2%26apos;-bipyridinium nitrate hydrate {[H4L%26apos;][NO3]center dot H2O}, 2, which was also structural characterised. The structure of 2 features an array of hydrogen-bonding interactions that generate a 3D network. More forceful heating of the acidic solution at 180 degrees C led to double decarboxylation and the formation of 4,4%26apos;-dicarboxy-2,2%26apos;-bipyridine, whereas heating at 200 degrees C led to total decarboxylation and the formation of 2,2%26apos;-bipyridine. Details of the structures of 1 and 2 along with their synthesis are discussed.

• 出版日期2013-7-1