Octahedral nickel(II) complexes are among the simplest systems that exhibit zero-field splitting by having two unpaired electrons. For the purpose of clarifying the relationship between structure and zero-field splitting in a low-symmetric system, distorted octahedral nickel(II) complexes were prepared with a tetradentate ligand, 2-[bis(2-methoxyethyl)aminomethyl]-4-nitrophenolate(1−) [(onp)⁻]. The complex [Ni(onp)(dmso)(H₂O)][BPh₄]·2dmso (1) (dmso = dimethyl sulfoxide) was characterized as a bulk sample by IR, elemental analysis, mass spectrometry, electronic spectra, and magnetic properties. The powder electronic spectral data were analyzed based on the angular overlap model to conclude that the spectra were typical of D₄-symmetric octahedral coordination geometry with a weak axial ligand field. Simultaneous analysis of the temperature-dependent susceptibility and field-dependent magnetization data yielded the positive axial zero-field splitting parameter D (H = g_uβS_uH_u + D[S_z² − S(S + 1)/3]), which was consistent with the weak axial ligand field. Single-crystal X-ray analysis revealed the crystal structures of [Ni(onp)(dmso)(H₂O)][BPh₄]·dmso (2) and [Ni(onp)(dmf)₂][BPh₄] (3) (dmf = N,N-dimethylformamide). The density functional theory (DFT) computations based on the crystal structures indicated the D₄-symmetric octahedral coordination geometries with weak axial ligand fields. This study also showed the importance of considering g-anisotropy in magnetic analysis, even if g-anisotropy is small.

An analytical processing design is proposed to accumulate nano-plastics diluted in water-based solvents and evaluate their individual IR spectral properties.

Water plays a significant role in the deterioration of reinforced concrete buildings; therefore, it is essential to evaluate the water content of the cover concrete. This study explores a novel non-destructive method for assessing the water content using sub-terahertz (sub-THz) waves. Among the four frequencies selected to evaluate the water content, an increase in reflectance was observed as the unit volume water content increased, and smaller data scatter was confirmed as the frequency increased. The derived empirical equation can classify the corrosion risk of the rebar environment based on the water content obtained using reflectance measurements. In other words, it can contribute to the diagnosis of the building integrity associated with rebar corrosion.