Yasunori Tsukahara

Enhanced debromination of brominated flame retardant plastics under microwave irradiation

Microwave irradiation of high impact polystyrene (HIPS-Br) containing brominated flame retardant i.e., decabromodiphenyl ether (DDO) or decabromodiphenyl ethane (DDE) was performed using aqueous and organic solvents for the removal of bromine. The microwave irradiation of HIPS-Br with triethylene glycol (TEG; 20 ml) at 250 °C for 30 min was found to be suitable condition for the removal of bromine (85 wt%) from the plastic, enabling recovery of the bromine free plastics.

Size-controlled synthesis of quantum-sized EuS nanoparticles and tuning of their Faraday rotation peak

Size-controlled EuS nanoparticles were synthesized by the reaction of europium metal with thiourea as a sulfur source in liq. NH3, whose surface was confirmed to be modified with thiourea by FT-IR measurement, and the opto-magnetic properties (Faraday effect) of the EuS nanoparticles were investigated by using PMMA films containing the nanoparticles, showing that their Faraday rotation peaks were adjustable by control of their particle size.

Synthesis, magnetic properties, and electronic spectra of mixed ligand bis(β-diketonato)chromium(III) complexes with a chelated nitronyl nitroxide radical: X-ray structure of [Cr(dpm)2(NIT2py)]PF6

A new series of nine nitronyl nitroxide Cr(III) complexes with various β-diketonates, [Cr(β-diketonato)2(NIT2py)]PF6, have been synthesized where NIT2py is 2-(2′-(pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-3-oxide-1-oxyl, and their structures, magnetic and optical properties have been examined. X-Ray analysis of [Cr(dpm)2(NIT2py)]PF6 (monoclinic, space group P21/a, a = 13.960(4), b = 31.19(1), c = 13.940(4), Z = 4) demonstrated that NIT2py coordinated to Cr(III) as a bidentate six-membered chelate. Variable-temperature magnetic susceptibility measurements indicated the antiferromagnetic interaction between Cr(III) and NIT2py with a variety of the magnetic coupling constant J values for these complexes. From the variable temperature or solvent dependent UV–vis spectra and MCD, and/or the resonance Raman spectra of the bis(β-diketonato)(NIT2py) Cr(III) complexes, the absorption components centered around 13.3 × 103 cm−1 were assigned to the formally spin-forbidden d–d transition within the t2g subshell associated with the intensity enhancement and the newly appeared vibronic bands around (16.0–18.0) × 103 cm−1 were due to the metal–ligand charge transfer [t2g–SOMO(π*) MLCT] transitions. The change of their spectroscopic characteristics with varying the β-diketonato ligands is discussed in connection with the antiferromagnetic coupling constant J values on the basis of the exchange mechanism along with the coligand effect. The luminescence spectra which show a large Stokes shift suggest the antiferromagnetic interaction in the lowest excited states originates from the 2E or 2T1 level of the Cr(III) moiety.

A novel linkage isomeric pair of mixed ligand Ni(II) complexes with IM2py-κ2N,O and IM2py-κ2N,N modes in [Ni(acac)(tmen)(IM2py)]+; synthesis and X-ray structure

This is the first report of a Ni(II) complex with the six-membered IM2py chelate coordinating via oxygen, [Ni(acac)(tmen)(IM2py-κ2N,O)]PF6 (1·PF6) (acac = acetylacetonate; tmen = N,N,N′,N′-tetramethylethylenediamine; IM2py = 2-(2-(pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxy). This new complex 1·PF6 has been synthesized by the direct reaction between [Ni(acac)(tmen)]PF6 and IM2py. The X-ray analysis (monoclinic, P21/c, a = 15.378(2), b = 13.331(2), c = 16.560(2) A, β = 116.377(6)°, Z = 4) demonstrated that the IM2py ligand is coordinated to Ni(II) as an unprecedent six-membered didentate chelate with the κ2N,O mode in 1. The corresponding linkage isomer, [Ni(acac)(tmen)(IM2py-κ2N,N)]PF6 (2·PF6), was obtained from the deoxygenation reaction of [Ni(acac)(tmen)(NIT2py)]PF6 with NaNO2. Variable-temperature measurements of the magnetic susceptibility and UV-vis absorption bands indicated a ferromagnetic interaction in 2·PF6 and an antiferromagentic one in 1·PF6. These facts confirm a linkage isomeric pair of [Ni(acac)(tmen)(IM2py-κ2N,O)]+ (1) and [Ni(acac)(tmen)(IM2py-κ2N,N)]+ (2) with oxygen and nitrogen coordination, respectively, in the IM moiety.