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In this paper, we report on the chiral crystallization of achiral mol­ecules., The compound, {6,6′-dimeth­oxy-2,2′-[(4-azaheptane-1,7-di­yl)bis­(nitrilo­meth­an­yl­idyne)]diphenolato}zinc(II) methanol monosolvate, [Zn(C22H27N3O4)]·CH3OH, at 298 K crystallizes in the ortho­rhom­bic space group Pna21. The Zn atom is coordinated by a penta­dentate Schiff base ligand in a distorted trigonal–bipyramidal N3O2 geometry. The equatorial plane is formed by the two phenolic O and one amine N atom. The axial positions are occupied by two amine N atoms. The distorted bipyramidal geometry is also supported by the trigonality index (τ), which is found to be 0.85 for the mol­ecule. In the crystal, methanol solvent mol­ecule is connected to the complex mol­ecule by an O—H⋯O hydrogen bond and the complex mol­ecules are connected by weak supra­molecular inter­actions, so achiral mol­ecules generate a chiral crystal. The Hirshfeld surface analysis suggests that H⋯H contacts account for the largest percentage of all inter­actions.

The crystal structure of the amino acid Schiff base copper(II) complex with a tridentate ligand synthesized from salicyl­aldehyde, l-threonine and copper(II) acetate is reported., In the title complex mol­ecule, [Cu(C11H11NO4)(CH4O)(H2O)], the Cu atom is coordinated in a distorted square-pyramidal geometry by a tridentate ligand synthesized from l-threonine and salicyl­aldehyde, one methanol mol­ecule and one water mol­ecule. In the crystal, the mol­ecules show intra- and inter­molecular O—H⋯O hydrogen bonds. The Hirshfeld surface analysis indicates that the most important contributions to the packing are H⋯H (49.4%) and H⋯O/O⋯H (31.3%) contacts.

Three 1-[(1,3-benzodioxol-5-yl)methyl]-4-(halobenzo­yl)piperazines adopt very similar mol­ecular conformations but, while the mol­ecules of the 3-fluoro­benzoyl are linked by hydrogen bonds into a three-dimensional structure, there are no hydrogen bonds in either of the 2,6-di­fluoro­benzoyl and 2,4-di­chloro­benzoyl analogues., In each of the compounds 1-[(1,3-benzodioxol-5-yl)methyl]-4-(3-fluoro­benzo­yl)piperazine, C19H19FN2O3 (I), 1-[(1,3-benzodioxol-5-yl)methyl]-4-(2,6-di­fluoro­benzo­yl)piperazine, C19H18F2N2O3 (II), and 1-[(1,3-benzodioxol-5-yl)methyl]-4-(2,4-di­chloro­benzo­yl)piperazine, C19H19Cl2N2O3 (III), the piperazine rings adopt a chair conformation with the (1,3-benzodioxol-5-yl)methyl substituent occupying an equatorial site: the five-membered rings are all slightly folded across the O⋯O line leading to envelope conformations. The dihedral angle between the planar amidic fragment and the haloaryl ring is 62.97 (5)° in (I) but 77.72 (12)° and 75.50 (5)° in (II) and (III), respectively. Despite their similarity in constitution and conformation, the supra­molecular inter­actions in (I)–(III) differ: in (I), a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds links the mol­ecules into a three-dimensional framework structure, but there are no hydrogen bonds of any sort in either (II) or (III), although the structure of (III) contains a short Cl⋯Cl contact between inversion-related pairs of mol­ecules.

Based on the potential redox and catalytic ability of oxovanadium complexes, our goal was to characterize the physical properties of two such complexes to be used as mediators for laccase. Computational studies, TD-DFT calculations and docking simulations were performed to elucidate the interaction between laccase and the two anionic complexes (aquabis(oxalato)oxidovanadate(IV) (1) and bis(oxalato)dioxidovanadate(V)) (2), respectively. Electrochemical measurements carried out on anion complexes of 1 and 2 docked into laccase were compared to laccase alone, showing changes in oxidation-reduction potential and current value, especially with the oxovanadium anion of 2. Since both internal tiny magnetic fields of ferromagnetic catalysts and external applied magnetic fields were found in previous investigations to constitute effective ways to improve the oxygen transfer rate, the magnetic susceptibility was measured. A valence change proneness was confirmed with higher valence for the oxovanadium anion of 2, which is in accordance with the electrochemical results.

Induced chirality (achiral target in chiral matrix such as proteins) sometimes play a useful role in evaluating supramolecular systems involving biomolecules. Enzymatic fuel cells, which generate electricity via enzymatic redox reactions at electrodes hold a significant potential for sustainable power. Bacterial laccase, a multi-copper oxidase, was used in the cathodic compartment of the enzymatic biofuel cells because of its low redox potential. Three new salen Cu(II) complexes were designed and investigated as mediators. The Schiff base ligands consisted of both a redox-active (anthraquinone) and a photochromic (azobenzene) moiety. The interaction between laccase and a mediator was examined with induced circular dichroism (CD) and the docking tool to observe in which of the laccase domains the mediators bind as well as study the photo-induced tuning of both the cis-trans photoisomerization and orientation by the Weigert effect. Both the electrochemical and photochromic properties are also discussed and compared using density functional theory (DFT), time-dependent (TD)-DFT, and docking simulations.

A salen-type Schiff base Zn(II) complex included in human serum albumin (HSA) protein was examined by UV-Vis, circular dichroism (CD), and fluorescence (PL) spectra. The formation of the composite material was also estimated by a GOLD program of ligand&ndash, protein docking simulation. A composite cast film of HSA and Zn(II) complex was prepared, and the effects of the docking of the metal complex on the degradation of protein molecules by mid-infrared free electron laser (IR-FEL) were investigated. The optimum wavelengths of IR-FEL irradiation to be used were based on experimental FT-IR spectra and vibrational analysis. Using TD-DFT results with 6-31G(d,p) and B3LYP, the IR spectrum of Zn(II) complex could be reasonably assigned. The respective wavelengths were 1652 cm&minus, 1 (HSA amide I), 1537 cm&minus, 1 (HSA amide II), and 1622 cm&minus, 1 (Zn(II) complex C=N). Degradation of HSA based on FT-IR microscope (IRM) analysis and protein secondary structure analysis program (IR-SSE) revealed that the composite material was degraded more than pure HSA or Zn(II) complex, the inclusion of Zn(II) complex enhanced destabilization of folding of HSA.

The title compound is composed of a benzene ring linked to an indazole unit by an N=N bond and has high planarity. The diazenyl group adopts a trans (E) conformation., The title azo compound, C16H16N4, was synthesized from 2,6-di­methyl­aniline. The diazenyl group adopts a trans (E) conformation, with an N=N bond length of 1.265 (4) Å. The pyrazole ring is approximately planar. In the crystal, zigzag chains along the b-axis direction with a C(3) is graph-set motif are formed by N—H⋯N hydrogen bonds involving the pyrazole moiety.

The planar achiral title compound has C 2v symmetry and crystallizes in the chiral space group P21., The title compound, C10H10O4, was synthesized from tetra­methyl-1,4-benzo­quinone. In the crystal, the almost planar mol­ecule (r.m.s. deviation = 0.024 Å) forms intra­molecular hydrogen bonds between the aldehyde and hy­droxy groups and exhibits C 2v symmetry. This achiral mol­ecule crystallizes in the chiral space group P21 with inter­molecular O—H⋯O and C—H⋯O hydrogen bonding and C—H⋯π and C=O⋯π inter­actions stabilizing the crystal packing.

In this study, we report the synthesis, characterization, and chiroptical properties of azo-group-containing chiral salen type Schiff base Ni(II), Cu(II), and Zn(II) complexes absorbed on gold nanoparticles (AuNPs) of 10 nm diameters. Induced circular dichroism (CD) around the plasmon region from the chiral species weakly adsorbed on the surface of AuNP were observed when there were appropriate dipole&ndash, dipole interactions at the initial states. Spectral changes were also observed by not only cis-trans photoisomerization of azo-groups but also changes of orientation due to Weigert effect of azo-dyes after linearly polarized UV light irradiation. Spatial features were discussed based on dipole-dipole interactions mainly within an exciton framework.

Chiral crystals were discovered due to spontaneous resolution when enantiomers of 4-phenyldiazenyl-2-[(R or S)-(1-phenylethyl)-iminomethyl]phenol and its racemic mixture were prepared. Using two ligands per molecule, optically active R,R and S,S enantiomers and meso R,S diastereomer of Cu(II) complexes were prepared. Strong chiral recognition was expected for them. Laccase has attracted attention as a catalyst that reduces oxygen to water in a cathode of biofuel cells, which can be effectively mediated by metal complexes. Furthermore, azobenzene can align perpendicularly to the polarization direction of irradiating linearly polarized ultraviolet light (Weigert effect) as well as to the conventional cis-trans photoisomerization accompanying the shift of redox potential. Thus, we also studied the photo-induced control of cis-trans forms and the alignment of these Cu(II) complexes as a mediator to fit laccase appropriately. We discuss photo-induced control on not only electronically but also sterically-favored redox conditions. The meso(R,S)-form of the Cu(II) complex in cis-form was found to be the best at increasing the current of cyclic voltammetry (CV) among the three R,R and S,S enantiomers and the R,S diastereomer of the Cu(II) complexes.

Department of Chemistry, Tokyo University of Science, Tokyo, Japan E-mail: akitsu2@rs.tus.ac.jp Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata-700 064, India E-mail: sayan23us@gmail.com Manuscript received online 03 March 2019, revised 17 April 2019, accepted 18 April 2019 Artificial metalloenzymes (ArM) have emerged as a promising strategy to emulate the catalytic efficiency of natural metalloenzymes in new to nature reactions. ArM consisting of lysozyme derived from hen egg white lysozyme (HEWL) and several chiral salen-type Cu(II) complexes was prepared in this study. Twenty types of salen-type metal complexes were obtained from crystal database and then were virtually screened with help of molecular docking procedure. Docking results verified that the Cu(II) complexes interacts with lysozyme by hydrogen and hydrophobic bonds. Four Cu(II) complexes with best docking score were synthesized. It was confirmed by the CV curve that there is an electrochemical difference between lysozyme simple substance and complex to attempt to reduce oxygen.

Department of Chemistry, Faculty of Science, Tokyo University of Science, Tokyo 162-3601, Japan E-mail: akitsu@rs.tus.ac.jp Department of Chemistry, National Institute of Technology, Rourkela-769 008, Odisha, India Department of Applied Sciences, Haldia Institute of Technology, Haldia-721 657, West Bengal, India Center for Molecular and Biophysics Research, Mar Ivanios College, Thiruvananthapuram-695 015, Kerala, India Manuscript received online 26 September 2018, accepted 03 October 2018 As a promising renewable energy, dye sensitized solar cell (DSSC) has been developed to improve performance of every material and system. From the viewpoint of dye metal complexes/organic compounds, we have reported on chiral Schiff base (salen-type) metal complexes and induced CD from chiral Schiff base metal complexes involving azo-dye groups to Au nanoparticles, and recently we have also conducted research on their optical interactions. In this paper, we showed the results of Z-scan NLO measurements for the analogous achiral organic ligands and metal complexes.

We have investigated linearly polarized UV light-induced molecular orientation due to Weigert effect of composite materials of new six binuclear nickel(II), copper(II), and zinc(II) complexes of two rigid Schiff base ring ligands (L1 and L2) composite materials with methyl orange (MO), an azo-dye, in polyvinylalchol (PVA) cast films. To compare the degree of molecular orientation, two ligands, namely flexible aliphatic cyclohexane (ML1: NiL1, CuL1, ZnL1) and rigid aromatic (ML2: NiL2, CuL2, ZnL2), were synthesized using amine moiety. We have also characterized these complexes by means of elemental analysis, IR, and UV-vis spectra, single crystal or powder X-ray diffraction (XRD) analysis, and so on. Composite materials of ML1 or ML2+MO+PVA were also prepared to separately disperse the solutes in a polymer matrix. For any metal complexes, optical anisotropy (represented as the R parameters) of ML2+MO+PVA was larger than ML1+MO+PVA because of the rigidness of the ligands.

Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan E-mail: akitsu@rs.kagu.tus.ac.jp Manuscript received 04 March 2018, accepted 11 March 2018 Laccase is mainly used as an enzyme of a cathode electrode of a biofuel cell. One problem is rate limiting of electron transfer between electrodes and enzymes. To enhance transfer of electron from the electrode to the redox center in the enzyme, using mediators instead of substrates of laccase is one the solution. A selection of the mediator is important in improving the performance of the biofuel cell. Our laboratory has succeeded in improving the electron transfer function by controlling the polarization-induced molecular orientation of a complex having an azo dye in a laccase matrix. In this study, we will synthesize a mononuclear complex including azobenzene, a binuclear complex and a tetranuclear complex containing CuII or MnII/III ions, and evaluate how much multistep electron transfer and molecular orientation by multinuclear complex will contribute to function as a mediator

Molecular orientation of dyes must be one of the important factors for designing dye-sensitized solar cells (DSSC). As model systems, we have prepared new hybrid materials composed of azobenzene (AZ) and chiral Schiff base Cu(II) complexes (pn(S)Cu and pn(R)Cu) in polymethyl methacrylate (PMMA) cast films. In addition to experimental results, in order to understand their behavior due to anisotropic alignment of them by linearly polarized UV light irradiation, the so-called Weigert effect, we treated theoretically and discussed based on computational chemistry and mathematical treatments (MD simulation and Bayesian statistics).

Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan E-mail : akitsu@rs.kagu.tus.ac.jp Fax : 81-3-5261-4631 Manuscript received 02 October 2017, revised 12 November 2017, accepted 14 November 2017 We reported on synthesis, characterization, and docking of supramolecular systems of azo-group containing chiral salen-type Schiff base NiII, CuII and ZnII complexes and colloidal gold nanoparticles (AuNPs) of 10 nm diameters. Appropriate conditions enabled some of them to exhibit induced CD from chiral species adsorbed on the surface of AuNPs. We have compared differences of dipole-dipole interactions of cis-trans isomerization as well as coordination geometries of these complexes associated with induce CD spectra around plasmon region. This optical features will be promising light absorption mechanism of dyes for solar cells developing new concept of organic/inorganic hybrid functional materials.

Department of Chemistry, Faculty of Science, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan E-mail : akitsu@rs.kagu.tus.ac.jp Department of Electrical Engineering, Faculty of Science and Technology, Tokyo University of Science, Chiba, Japan Department of Chemistry, Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India Manuscript received 02 May 2017, accepted 08 May 2017 Dye sensitized solar cells (DSSC) emerged as a new class of low cost energy conversion devices. In this study, we investigated a class of transition metal complexes [ML(CH3OH)]; M = Mn(1), Fe(2), Co(3), Ni(4), Cu(5) and Zn(6) and H2L is naphthyl-salen Schiff base ligand. The COOH group of the complexes leads to better ability for adsorption of dyes. These complexes were characterized employing elemental analysis, powder X-ray analysis, IR, UV-Vis-NIR electronic spectroscopy and so on. Light absorption of the all the complexes shows that π-conjugated naphthyl ring makes these complexes efficient as dyes in DSSC. However, spatial distribution of excited orbitals associated with absorption properties (UV-Vis absorption spectra) calculated by TD-DFT method revealed one of the important factors about orbitals and molecular design of metal complexes for DSSC dyes.