The thermodynamic parameters of complexation of Ln(III) cations with tris(2-aminoethyl)amine (tren) and tetraethylenepentamine (tetren) were determined in dimethyl sulfoxide (DMSO) by potentiometry and calorimetry. The excitation and emission spectra and luminescence decay constants of Eu3+ and Tb3+ complexed by tren and tetren, as well as those of the same lanthanides(III) complexed with diethylenetriamine (dien) and triethylenetetramine (trien), were also obtained in the same solvent. The combination of thermodynamic and spectroscopic data showed that, in the 1:1 complexes, all nitrogens of the ligands are bound to the lanthanides except in the case of tren, in which the pendant N is bound. For the larger ligands (trien, tren, tetren) in the higher complexes (ML2), there was less complete binding by available donors, presumably due to steric crowding. FT-IR studies were carried out in an acetonitrile/DMSO mixture, suitably chosen to follow the changes in the primary solvation sphere of lanthanide(III) due to complexation of amine groups. Results show that the mean number of molecules of DMSO removed from the inner coordination sphere of lanthanides(III) is lower than ligand denticity and that the coordination number of the metal ions increases with amine complexation from approximately 8 to approximately 10. Independently of the number and structure of the amines, linear trends, similar for all lanthanides, were obtained by plotting the values of DeltaGj degrees, DeltaHj degrees, and TDeltaSj degrees for the complexation of ethylenediamine (en), dien, trien, tren, and tetren as a function of the number of amine metal-coordinated nitrogen atoms. The main factors on which the thermodynamic functions of lanthanide(III) complexation reactions in DMSO depend are discussed.

Linear phenolic-epoxy polymers were cured with diaminodiphenyl sulfone (DDS), metaphenylene diamine (m-DPA), and phenolic aldehyde amine (PAA), respectively, to prepare several anti-corrosion materials that are coating components. The effect of different curing agents on energy of activation (E a ) and glass transition temperature (T g ) of polymers was investigated using differential scanning calorimetry (DSC). E a of phenolic-epoxy/DDS is higher than that of phenolic-epoxy/ PAA, and lower than that of phenolic-epoxy/m-DPA. The three anti-corrosion materials were immersed in 10% sulfuric acid (H 2 SO 4 ) solution at 80°C for 800 h. T g of phenolic-epoxy/ DDS material varies very little before and after acid immersion testing, while T g of phenolic-epoxy/PAA material drastically decreases after the acid immersion test. A gravimetric liquid sorption experiment indicates that weight loss of phenolic-epoxy/DDS material is the smallest among three anticorrosion materials. X-ray photoelectron spectroscopy (XPS)analysis demonstrates that the carbon-to-oxygen (C/O) ratio of phenolic-epoxy/DDS material after exposure testing is higher than that of phenolic-epoxy/m-DPA material and phenolic-epoxy/PAA material. The high T g , high C/O ratio, and low weight loss of phenolic-epoxy/DDS material as a coating component during exposure are connected directly with the strong corrosion resistance of the coating.

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.