RESUMO
The reaction of diphenylphosphinobenzenesulfonic acid with copper(i) oxide resulted in the formation of the new neutral dimeric copper(i) complex {Cu2(DPPBS)2·(MeOH)2}. X-ray diffraction studies revealed that the complex has a dimeric structure and a pyramidal trigonal geometry around the copper atom which contains coordinated methanol molecules at the copper centers. Cleavage of the dimer by reaction with various bipyrimidines enabled the preparation of the corresponding well-defined heterotopic mononuclear [Cu(P^O)(N^N)] and dinuclear {(P^O)Cu(N^N)Cu(P^O)} complexes. X-ray crystal structure determination shows these to have distorted tetrahedral geometries. Their absorption and emission properties were investigated experimentally and photophysical data were also confirmed by DFT and TD-DFT calculations. Owing to the methanol molecules, the neutral crystalline dimer {Cu2(DPPBS)2·(MeOH)2} displays green reversible photoluminescence upon UV irradiation in the solid state with an absolute luminescence quantum yield of 0.51.
RESUMO
One-meter sediment cores sampled in a marina have been submitted to extensive characterization and organotin speciation. Geochemical homogeneity has been demonstrated. Butyltin species are present at all depths with a predominance of TBT or MBT in the upper or lower layers, respectively. Seasonal variations of butyltin compounds have been identified and together with a knowledge of local conditions we estimate the sediment layers represent 14 years of deposition. A first order multi-step kinetic model of the sequential degradation of TBT in, successively, DBT, MBT and Sn (IV) is proposed. The half-life of TBT was estimated (on a 14-year period) to be 2.1 years and those of DBT and MBT (on a 5-year period) 1.9 and 1.1 years, respectively.
