Theoretical Study on Magnetic Interaction in Pyrazole-Bridged Dinuclear Metal Complex: Possibility of Intramolecular Ferromagnetic Interaction by Orbital Counter-Complementarity

A possibility of the intramolecular ferromagnetic (FM) interaction in pyrazole-bridged dinuclear Mn(II), Fe(II), Co(II), and Ni(II) complexes is examined by density functional theory (DFT) calculations. When azide is used for additional bridging ligand, the complexes indicate the strong antiferromagnetic (AFM) interaction, while the AFM interaction becomes very weak when acetate ligand is used. In the acetate-bridged complexes, an energy split of the frontier orbitals suggests the orbital counter-complementarity effect between the dxy orbital pair, which contributes to the FM interaction; however, a significant overlap of other d-orbital pairs also suggests an existence of the AFM interaction. From those results, the orbital counter-complementarity effect is considered to be canceled out by the overlap of other d-orbital pairs

Theoretical Study on the Difference in Electron Conductivity of a One-Dimensional Penta-Nickel(II) Complex between Anti-Ferromagnetic and Ferromagnetic States—Possibility of Molecular Switch with Open-Shell Molecules

The electron conductivity of an extended metal atom chain (EMAC) that consisted of penta-nickel(II) ions bridged by oligo-α-pyridylamino ligands was examined by density functional theory (DFT) and elastic scattering Green’s functions (ESGF) calculations. The calculated results revealed that an intramolecular ferromagnetic (FM) coupling state showed a higher conductivity in comparison with an anti-ferromagnetic (AFM) coupling state. The present results suggest the potential of the complex as a molecular switch as well as a molecular wire

Quantum Chemical Design Guidelines for Absorption and Emission Color Tuning of fac-Ir(ppy)3 Complexes

The fac-Ir(ppy)3 complex, where ppy denotes 2-phenylpyridine, is one of the well-known luminescent metal complexes having a high quantum yield. However, there have been no specific molecular design guidelines for color tuning. For example, it is still unclear how its optical properties are changed when changing substitution groups of ligands. Therefore, in this study, differences in the electronic structures and optical properties among several substituted fac-Ir(ppy)3 derivatives are examined in detail by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. On the basis of those results, we present rational design guidelines for absorption and emission color tuning by modifying the species of substituents and their substitution positions

Theoretical Study on Redox Potential Control of Iron-Sulfur Cluster by Hydrogen Bonds: A Possibility of Redox Potential Programming

The effect of hydrogen bonds around the active site of Anabaena [2Fe-2S] ferredoxin (Fd) on a vertical ionization potential of the reduced state (IP(red)) is examined based on the density functional theory (DFT) calculations. The results indicate that a single hydrogen bond increases the relative stability of the reduced state, and shifts IP(red) to a reductive side by 0.31–0.33 eV, regardless of the attached sulfur atoms. In addition, the IP(red) value can be changed by the number of hydrogen bonds around the active site. The results also suggest that the redox potential of [2Fe-2S] Fd is controlled by the number of hydrogen bonds because IP(red) is considered to be a major factor in the redox potential. Furthermore, there is a possibility that the redox potentials of artificial iron-sulfur clusters can be finely controlled by the number of the hydrogen bonds attached to the sulfur atoms of the cluster

Characterization of heterozygous ATTR Tyr114Cys amyloidosis-specific induced pluripotent stem cells

Hereditary transthyretin (TTR) amyloidosis (ATTRv amyloidosis) is autosomal dominant and caused by mutation of TTR gene. Heterozygous ATTR Tyr114Cys (p.Tyr134Cys) amyloidosis is a lethal disease with a life expectancy of about 10 years after onset of the disease. However, the molecular pathogenesis of ATTR Tyr114Cys amyloidosis is still largely unknown. In this study, we took advantage of disease-specific induced pluripotent stem (iPS) cells and generated & characterized the heterozygous ATTR Tyr114Cys amyloidosis-specific iPS cells (Y114C iPS cells), to determine whether Y114C iPS cells could be useful for elucidating the pathogenesis of ATTR Tyr114Cys amyloidosis. We successfully differentiated heterozygous Y114C iPS cells into hepatocyte like cells (HLCs) mainly producing TTR protein. On day 27 after differentiation, the expression of hepatocyte maker albumin was detected, and TTR expression was significantly increased in HLCs differentiated from Y114C iPS cells. LC–MS/MS analysis showed that both WT TTR & ATTR Y114C protein were indeed expressed in the HLCs differentiated from Y114C iPS cells. Notably, the number of detected peptides derived from ATTR Y114C protein was lower than that of WT TTR protein, indeed indicating the clinical phenotype of ATTR Tyr114Cys amyloidosis. Taken together, we first reported the heterozygous Y114C iPS cells generated from patient with ATTR Tyr114Cys amyloidosis, and suggested that Y114C iPS cells could be a potential pathological tool, which may contribute to elucidating the molecular pathogenesis of heterozygous ATTR Tyr114Cys amyloidosis

Generation of familial amyloidotic polyneuropathy-specific induced pluripotent stem cells

Familial amyloidotic polyneuropathy (FAP) is a hereditary amyloidosis induced by amyloidogenic transthyretin (ATTR). Because most transthyretin (TTR) in serum is synthesized by the liver, liver transplantation (LT) is today the only treatment available to halt the progression of FAP, even though LT is associated with several problems. Despite the urgent need to develop alternatives to LT, the detailed pathogenesis of FAP is still unknown; also, no model fully represents the relevant processes in patients with FAP. The induction of induced pluripotent stem (iPS) cells has allowed development of pluripotent cells specific for patients and has led to useful models of human diseases. Because of the need for a tool to elucidate the molecular pathogenesis of FAP, in this study we sought to establish heterozygous ATTR mutant iPS cells, and were successful, by using a Sendai virus vector mixture containing four transcription factors (Oct3/4, Sox2, Klf4, and c-Myc) to reprogram dermal fibroblasts derived from FAP patients. Moreover, FAP-specific iPS cells had the potential to differentiate into hepatocyte-like cells and indeed expressed ATTR. FAP-specific iPS cells demonstrated the possibility of serving as a pathological tool that will contribute to understanding the pathogenesis of FAP and development of FAP treatments