Unusual oxidation of an N-heterocycle ligand in a metal-organic framework

An in situ ligand reaction from the pyridine cycle to -COO- in the copper-organic framework is achieved under hydrothermal conditions. Compound [Cu-2(bpa)(4)] [1; bpa = 5-(4-bromophenyl)picolinic acid] exhibits a one-dimensional chain architecture based on weak Cu-O interactions. The mechanism of ligand transformation is discussed.