Magnetic resonance in relaxed excited states AX and AT of Ga+ in alkali halides

The optical detection technique is used to observe magnetic resonance in the excited states ³T_1u of Ga⁺ in KI, KC? and NaC?. The relaxed excited states A_X and A_T display trigonal and tetragonal symmetry respectively, as a result of a static Jahn-Teller effect. Furthermore the coupling to E_g and T_2g modes is found to be nearly equal in KI : Ga⁺, as already observed in KBr : Ga⁺.     

Polymerizations of vinyl methacrylate and vinyl acrylate

Both vinyl methacrylate (VMA) and vinyl acrylate (VA) were homopolymerized by n-butyllithium catalyst at ?78°C. Both of the anionic polymers were soluble in common organic solvents, and only vinyl group was contained in the polymers. Both of the monomers were homopolymerized by free-radical catalysts under different conditions. The soluble polymers were obtained under low monomer concentrations and at low conversions. It was estimated by NMR and infrared spectroscopy that both the soluble polymers contained mainly a vinyl group, similar to the anionic polymers. The soluble VMA polymers comprised 10–20% cyclic units for monomer concentrations ranging from 1.8 to 0.5 mole/I. The soluble VA polymers comprised 50–60% cyclic units for monomer concentrations ranging from 0.9 to 0.3 mole/l. It was suggested that the cyclic units did not consist of γ-lactone but of larger-membered rings than δ-lactone or of ladder structural units. The difference between the cyclization content of poly-VMA and that of poly-VA might be explained by the copolymerization data of the reference monomers.     

Interdependence of Anion and Cation Exchanges in Calcium Hydroxyapatite: Pb(2+) and Cl(-)

The ion exchange of Pb(2+) and Cl(-) into calcium hydroxyapatite from aqueous solutions is studied at 293 K. Although the exchange of Cl(-) into CaHAp and PbHAp was not observed, in the presence of both Pb(2+) and Cl(-) in aqueous solution the exchange of both Pb(2+) and Cl(-) into CaHAp occurred, and, at least at intermediate concentrations of HCl, a proportionality between the sorbed quantities of these two ions was observed. The dissolution of CaHAp is shown to be dependent upon the pH, while the quantity of Pb(2+) exchanged into the solid is not a function of the proton content; consequently, the exchange is not primarily a dissolution-precipitation process. Copyright 1999 Academic Press.     

In vivo evaluation of carborane gadolinium-DTPA complex as an MR imaging boron carrier

The evaluation of the Gd-carborane complex 2 as an MR imaging and boron carrier agent was carried out in vivo using tumor-bearing Donryu rats, MRI, ICP-AES, and alpha-autoradiography. The MR imaging revealed that the carborane Gd-DTPA 2 was metabolized slower in the body than Gd-DTPA 1. The results of the ICP-AES method indicated that compound 2 was incorporated into normal tissues and metabolized quickly, whereas it was not accumulated into tumor or brain tissue. The alpha-autoradiography showed that a high level of boron was obtained in the internal organs and in the necrosis of tumor tissue.     

Homoleptic lanthanide triple-deckers of 5,15-diazaporphyrin with D2h symmetry

Two novel homoleptic diazaporphyrinato lanthanide sandwich com-plexes M(2)(DAP)(3) [M = Ce (1), Eu (2); DAP= 2,8,12,18-tetra-ethyl-3,7,13,17-tetramethyl-5,15-diazaporphyrinate] were synthesized by a one-pot reaction of the corresponding M(acac)(3).nH(2)O (acac = acetylacetonate) with metal-free D(2)(h) type diazaporphyrin, H(2)DAP. The spectroscopic and electrochemical properties are compared with those of complexes based on D(4)(h) symmetry porphyrin ligands.