A dirhodium(II,II) molecular species as a candidate material for resistive carbon monoxide gas sensors

A new semiconducting material based on the dirhodium(II,II) square molecular box complex, [Rh2(form)2(ox)]4 (1), has been proposed as a sensing layer for resistive gas sensors. Deposition of thin films of 1 by spin-coating on an interdigited alumina substrate has allowed to fabricate a resistive sensor presenting peculiar sensing properties towards CO detection. The response–concentration relationship found is linear in a wide range of CO concentrations (100–50,000 ppm). The increase of resistance observed under CO atmosphere has been attributed to a modification of the electronic environment along the dirhodium(II,II) centers due to CO-coordination. The sensor shows also a high selectivity for CO with respect to methane and NO2 investigated as interfering gases.