Guidelines proposed for designing organic ferromagnets by using a quantum chemical approach

For predicting the characteristics of organic ferromagnetic substances, we have previously proposed a simple rule for conjugated organic molecules based on molecular orbital coefficients by the simple Hückel??s nonbonding molecular orbital (NBMO) method. In this work, we extended the rule to systems including heteroatoms to become more widely applicable to various magnetic polymers. It was proven that the linkage between molecules having an NBMO conserves the original NBMO levels even for the supermolecule after the linkage. In addition, we have also proposed an index to estimate the amount of possessing ferromagnetic property. The reliability of the rule and index is examined by applying both the density functional theory (DFT) with functional methods, i.e., B3LYP, B3PW91, BLYP, PBEPBE, and PBEP86, and the complete active space SCF (CASSCF) calculations to several model molecules.     

Ferromagnetic interaction in iron(II)–bis-Schiff base complexes

The preparation and magnetic properties of three Fe(II)–bis-Schiff base complexes, [Fe₂(L1)2(4,4′-bpy)] · MeOH (1), [Fe(L2)(EtOH)] (2) and [Fe(L3)(MeOH)] (3) (L1 = N,N′-bis(2-hydroxy-1-naphthaldehyde)-1,2-phenylenediimine; L2 = N,N′-bis(salicylidene)-1,2-phenylenediamine; L3 = N,N′-bis(5-Cl-salicylidene)-1,2-phenylenediamine; 4,4′-bpy = 4,4′-bipyridine) are reported. X-ray single crystal structure analyses for 1–3 reveal that 1 shows a dinuclear Fe(II)–bis-Schiff base complex bridged by 4,4′-bpy, while 2 and 3 show mononuclear structures. Molecular packing of 2 shows a uniform one-dimensional chain structure through hydrogen bonds and Fe?π interaction and that of 3 indicates significant π–π interaction to form a dimmer structure. The χT–T plots of 1–3 show all ferromagnetic interaction at low temperature. The origin of the ferromagnetic interaction observed in 2 is tentatively ascribed to the dimer formation through Fe?π interaction at low temperature.     

Revisiting the Bromination of CH Bonds with Molecular Bromine by Using a Photo‐Microflow System

The photobromination of C?H bonds by using molecular bromine was reinvestigated under microfluidic conditions. The continuous‐flow method suppressed the production of dibrominated compounds and effectively produced the desired monobrominated products with high selectivity. Rapid bromination of benzylic substrates containing a photoaffinity azide group was achieved without any decomposition.     

A plastic scintillator film for an electron beam-excitation assisted optical microscope

Optical Review - A plastic scintillator film for use in an electron beam excitation-assisted (EXA) optical microscope is characterized. The thin film scatters an incident electron beam weakly and...     

Ab initio MO analysis of interaction paths between radicals in ferromagnetic organic systems

Interaction path analyses for pi-conjugated organic systems were performed at the ab initio molecular orbital level to examine the relationship between inter-radical interactions and the high-spin stability of the system. It was found that the high-spin stability results from through-bond interactions between radicals, not from through-space interactions, in relation to the stabilization of a low-spin state due to the effects of electron correlation. L(ij)(min) value for estimating the mixing of nonbonding molecular orbitals well predicted the relationship between the through-bond interactions and the high-spin stability. Furthermore, molecular orbital calculations revealed that the all-trans type interaction path between radicals produces long-range exchange interactions, and the additivity of high-spin stability is observed by keeping short-range through-bond interaction paths.     

Theoretical study on nonlinear optical properties of metalloporphyrin using elongation method

A quantum-chemical analysis of the central metal effect on the (hyper)polarizabilities of meso-meso-linked metalloporphyrin (MP) oligomers was carried out using elongation finite-field (ELG-FF) method. It is found that meso-meso-linked MPs exhibit evident evolution of the third-order nonlinear optical (NLO) response (γ) along with an increasing number of porphyrin units N. The order of γ values is as following: γ_Mg > γ_Zn > γ_Ni. In contrast to the polarizability, the γ values of meso-meso-linked MPs are sensitive to the metals, that is, the nature of the metal can influence the third-order NLO response of MPs. However, the band structures for three MPs are similar to each other, and the differences on the band gaps of three MPs are very small. The local density of states (LDOSs) shows that the central metal gives the significant contributions for unoccupied bands in meso-meso-linked MPs.