The first alternating MnII-MnIII 1D chain: structure, magnetic properties and catalytic oxidase activities

An unprecedented one-dimensional mixed-valence chain, [{Mn-III(L)(2)}{Mn-II(bpy)(2)}(ClO4)(H2O)(0.5)] (H2L = N-salicylidene-l-alanine and bpy = 2,2-bipyridine), has been synthesized. The complex has been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, and variable-temperature magnetic measurements. The structural analysis reveals that the [Mn(bpy)(2)](2+) unit is linked to the pendent carboxylate arm of the [Mn-III(L)(2)](-) unit to produce a unique syn-anti carboxylate bridged 1D coordination polymer. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of antiferromagnetic interaction between the Mn-III and Mn-II centres with J = -0.98(2) cm(-1). Using 3,5-di-tert-butylcatechol (3,5-DTBC) and o-aminophenol (OAPH) as the substrates, the catecholase-like activity and phenoxazinone synthase-like activity of the complex have been studied; the turnover numbers (k(cat)) for these oxidase reactions have been calculated to be 126.9 and 738.0 h(-1), respectively.