Dimerization of Cobalt (II) Tetrasulfonated Phthalocyanine in Water and Aqueous-Alcohol Solutions.
Abstract
Metal complexes of tetrasulfonated phthalocyanine (TSPC) are of interest as oxidation and hydrolysis catalysts for thioethers and organophosphonates. Since metal TSPC complexes aggregate in aqueous solution, it was necessary to determine the dimerization constant as a prerequisite to establishing the efficacy of the monomeric Cobalt (II) TSPC (CoTSPC) complex as a catalyst. Since these potential catalysts will be used in mixed solvents to dissolve thioethers, the aggregation of CoTSPC was measured in alcohol-water solutions at various temperatures. This study uses a nonlinear, least-squares program to compute best-fit molar absorbances for monomers and dimers simultaneously. In addition, the monomer-dimer equilibrium is investigateed over a wide temperature range, 5-75 C, in water to determine if the standard enthalpy of formation varies with temperature. It was found that the enthalpy was temperature-dependent, possessing a constant value of Delta C subscript p deg. of 0.1 kcal/mole-K. It was also shown that earlier investigators deduced dimerization constants that were smaller than the ones reported in this investigation. We feel this was caused by the presence of higher aggregates and unwarranted assumptions in the method to estimate the dimerization constant. It is also shown that the dye, CoTSPC, behaves as typical non-aqueous solute, and that hydrophobic bonding is not involved in the formation of the dimer. Originator supplied keywords include: Cobalt (II) complexes; Monomer-dimer equilibria; Thermodynamics; Methanol-water solution; Dyestuffs; Tetrasulfonated and Phtalocyanine.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1985
- Accession Number
- ADA157572
Entities
People
- J. R. Ward
- R. P. Seiders
- Y. Yang