The chemistry of molecules displaying novel topologies has experienced an explosive development in the course of the last 25 years. The fast growth of this field originates to a large extend from the new templated synthetic methods which allow to prepare these compounds at a real macroscopic level. Our group, in particular, has proposed a particularly efficient copper(I)-based template synthesis of a large variety of catenanes and rotaxanes at an early stage, participating in the revival of molecular topology. One of the highlights of the field has been the synthesis of the trefoil knot, a particularly challenging target. This object is not only an aesthetically attractive molecule but it also displays interesting properties in relation to coordination chemistry and chirality. A highly promising extension of molecular topology is that of molecular machines. By combining the specific properties of catenanes and rotaxanes, i.e. marked flexibility and propensity to undergo large amplitude motions, and coordination chemistry, it has been possible to elaborate and study a large variety of molecular machines. A representative example is that of an adjustable receptor, based on a [3]rotaxane attached to two mobile porphyrinic plates. This compound and related molecules will lead to "molecular presses" and, eventually, to molecular machines usable in solution to catalyse reactions or change the conformation of given substrates. Another recent molecular machine prototype from our group is a [2]rotaxane which behaves as a molecular shuttle, the gliding motion of the threaded ring being fast and taking place over a relatively large distance. Such sophisticated molecular machine prototypes could lead to transport of matter over long distances or across membranes by proper modifications of the present systems and attachment of receptors on the mobile part of the shuttling machine.

抄録全体を表示

In this account, typical achievements for these 30 years related to metalloprotein electrochemistry using various functional electrodes and related fields are reviewed, for which JSCC award of 2009 was honorary presented to the author. The main achievements are: 1) the developments of functional electrodes for the direct rapid electron-transfer of metalloproteins, such as cytochrome c, myoglobin and ferredoxin, and their applications to analyze the biological functions of the metalloproteins using usual electrochemical techniques. Some surface structures of the electrodes at the molecular level have been studied to understand the surface functions of the electrode for the rapid electron transfer of metalloproteins on the electrode surfaces. 2) Biological functions of key amino-acids of myoglobin and ferredoxin have also been studied by comparing electrochemical behavior with those of mutated molecules. 3) Electrochemistry of metal-complexes, as models of metalloproteins, and its application to develop electrochemical-sensing devices, are also given. In addition, 4) recent developments on direct electron-transfer of enzymes, and new sugar (such as glucose and fructose) -air bio-fuel batteries at the level of practical use, >10 mA/cm² in current and > a few mW/cm² in power, are introduced.

抄録全体を表示

In this article, our study of dynamic NO ligands on ruthenium complexes has been reported. Transformation of NO ligand, linear NO⁺ and bent NO^- form, is characteristic of NO ligand on transition metal complexes. However, such transformation and incorporation of NO ligand into organic molecules, the so-called dynamic NO ligands, have little observed. We found three types of the dynamic NO ligands. First topic is interconversion of NO ligand (linear NO⁺ and bent NO^- form) in the chemistry of [2+2] cycloaddition reaction and protonation of vinylidene ruthenium complexes. In second topic, interesting reactivity of NO ligand on ruthenium complexes is described, where C–H activation and N–C coupling of NO ligand are included. Final attention is drawn to unprecedented N–N coupling of NO ligands on dinuclear ruthenium complexes. This N–N coupling is closely related with bacterial nitric oxide reductase (NOR). Use of the N–N coupling complexes achieved stepwise reproduction of the NOR catalytic process. These findings lead to new aspects in the chemistry of NO ligand on ruthenium complexes.

抄録全体を表示

This review article describes synthetic chemistry and materials science of metal-fullerene complexes. The contents include six topics: 1) Development of synthetic methodology for metal-fullerene complexes where group 6-10 metal atoms are directly attached to organofullerenes. 2) Organometallic chemistry of cationic chiral metal-fullerene carbene complexes and their application to asymmetric synthetic organic chemistry. 3) Creation of liquid crystalline metal-fullerene complexes and their multi redox properties. 4) Synthesis and electrochemistry of polymetallic [60]fullerene and [70]fullerene complexes and the electronic interactions among the metal atoms through the fullerene p-electron conjugated systems. 5) Ultrafast and multi-step photo-induced charge separation systems using donor/acceptor-type metal-fullerene complexes. 6) Photocurrent generating self-assembled monolayers of rigid and compact pentapod metal-fullerene complexes and change of photocurrent direction by the change of component and molecular orientation. The knowledge of the synthesis, supramolecular ordered structure formations, and photoelectrochemical functions of the metal-fullerene complexes is applicable to development of intelligent photoelectric conversion systems.

抄録全体を表示

This account reports recent development of linearly ordered multinuclear transition-metal complexes, or molecular metal atom chains, supported by multidentate phosphines, which could be important motifs for nano-structured molecular devices. In particular, it focuses on our recent results of platinum-based homo- and hetreromultimetallic complexes supported by a triphosphine ligand, bis(diphenylphosphinomethyl)phenylphosphine (dpmp), in which strategic synthetic methods of cluster core expansion have been established from Pt₂ complexes to Pt-Pt-M (M = Pt, Pd, Ir, Rh, Au, Ag, Cu) and Pt-M-Pt (M = Pt, Pd), and to the linear Pt₂M₂Pt₂ molecular chains (M = Pt, Pd) as well as one-dimensional assemblage of the linear Pt₃ units connected by bisisocyanide linkers. A linear tetraphosphine, meso-bis{(diphenylphosphinomethyl)phenylphosphino}methane (dpmppm), was synthesized to support linearly ordered tetranuclear metal chains, leading to successful isolation of the linear Pd₈ complexes, [Pd₈(μ-dpmppm)₄]⁴⁺ and [Pd₈(μ-dpmppm)₄(XylNC)₂]⁴⁺ (Xyl = 2,6-xylyl) which showed a Pd-Pd bonded linear structure and an interesting thermochromic behavior. The dpmppm ligand also supported flexibly bending Au₄ complexes with a photochemical switch upon recognizing counter anions, and Au₄M₂Cu₂ heterometallic rings, [{Au₂MCuCl₂(μ-dpmppm)₂}₂]⁴⁺ (M = Au, Ag, Cu), exhibiting strong inclusion behavior for a BF₄^- anion into pore of the Au₄Ag₂Cu₂ ring.

抄録全体を表示

In this review, we focus on the recent development of conjugates between nanoparticles (NPs) and biomolecules such as DNAs, as well as a brief history for inorganic bioconjugate chemistry. NP-biomolecule combination is heterogeneous and thus challenging. This research area was begun about a decade ago as a basic attempt to align AuNPs along DNA. Today, NP–DNA is a current topic whose developments can be applied in diagnosis, new devices, and drug delivery systems. Among these, the nanoscaled patterning of mesoscale NPs is the vital target of current material science, in which the conjugation of gold (Au) NPs and biomolecules is gaining immense importance. The positioning or alignment of NPs on the desired points of highly constructed DNA architectures is an important step for “DNA lithography” that leads to new electronic and optical devices. This review also introduces the current topics in the DNA architecture and its application for AuNP alignment.

抄録全体を表示

Time-dependent density functional theory has been successfully applied to analyze circular dichroism spectra of Δ- or Λ- octahedral metal complexes with bidentate ligands containing both s- and p-orbitals. Rotatory strengths associated with electronic transitions not only d-d transition but also ligand to metal charge transfer (LMCT) and π-π* transitions can be interpreted in terms of transition moments for excitations of metal complexes containing ligand moieties within a qualitative framework.

抄録全体を表示

Metal-organic frameworks on electrode surfaces have been developed via bottom-up syntheses to fabricate a promising catalytic device with specific shape and sized nanospaces. A metal-organic framework of Cu₃(btc)₂ (btc = 1,3,5-benzenetricarboxylate ion) on the surface-modified electrodes has been constructed by a layer-by-layer method. Morphology of Cu₃(btc)₂ was successfully controlled depending on the surface-modified molecules.

抄録全体を表示