SYNTHESES, SOLUBILITIES AND OXYGEN ABSORPTION PROPERTIES OF NEW COBALT(II) SCHIFF-BASE COMPLEXES

The syntheses, solubilities and oxygen absorption properties of cobalt (II) complexes of bis(salicylidene)-2,2'-dimethyl-1,3-propanediimine l igand derivatives, termed CoSaldmpr, are reported. These are homologs of the well-known N,N'-bis(salicylidene)ethylenediiminocobalt(II) (CoS alen) complexes, in which a 2,2-dimethyl-1,3-propanediimino bridging g roup replaces the ethylenediimino bridging group of CoSalen. Solubilit y data and limited oxygen-carrying properties bf the complexes in 1-me thyl-2-pyrrolidinone (NMP) solution, either alone or in the presence o f 2-cyanopyridine (2 M) as an axial base, are reported. Oxygen transpo rt of the solutions is tested with a flow system and a thermal swing p rocess with O-2 absorption conditions of 37 degrees C and desorption c onditions of 100-180 degrees C. The two CoSaldmpr complexes that are t ested have higher solubilities and oxygen affinities than the CoSalen homologs. In NMP solution with 2 M 2-cyanopyridine axial base, loading of Co(3-methoxy-Saldmpr), measured in (g O-2/g solution) remains abou t 35% higher than Co(3-methoxy-Salen) for at least four absorption/des orption cycles. (C) 1997 Elsevier Science Ltd.