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A novel tripodal ligand, tris[(4'-methyl-2,2'-bipyridin-4-yl)methyl]carbinol (tb-carbinol) and its homonuclear and heteronuclear Ru(II)-Re(I) complexes have been synthesized and characterized by NMR spectroscopy, elemental analysis, and mass spectroscopy. The spectroscopic, electrochemical and photocatalytic properties of the Ru(II)-Re(I) complexes have been investigated. In these supramolecular complexes with tb-carbinol as a bridging ligand, the intramolecular interaction among the terminal metal centers is very weak. In the cases of Ru(II) and Re(I) heteronuclear systems, when the Re(I) moieties are excited, the emission from the Re(I) moiety is efficiently quenched and the intensity of the emission from the Ru(II) moiety increases. The rate constant of energy transfer from Re(I) moieties to Ru(II) unit in RuRe(2) is 1.7 x 10(8) s(-1). From the point of view of the free energy change, the intramolecular electron transfer from the Ru(II) moiety to the Re(I) moiety could proceed smoothly in the ground state. Both of Ru(2)Re and RuRe(2) show excellent photocatalytic activities to the CO(2) reduction. RuRe(2) exhibits a turnover number of 190 for CO formation compared with 89 from the model complexes system after 16 h of irradiation (TN(CO) calculated based on Ru(II) moiety concentration). Ru(2)Re shows a higher turnover number than the model complexes system, 110 compared with 55 from the model system (TN(CO) calculated based on Re(I) moiety concentration). The bridging ligand of Ru(II)-Re(I) heteronuclear tripodal systems, tb-carbinol, plays an important role in converting radiant energy to chemical energy in the form of CO from CO(2). Enhancement of the photocatalytic response to light in the visible region has been achieved by fabricating supramolecular systems featuring covalently linked Ru(II) and Re(I) moieties.

A new bridging ligand, 1,3-bis(4′-methyl-2,2′-bipyridin-4-yl)propan-2-one (L) and its mono- and dinuclear Ru(II) complexes have been synthesized and characterized. The carbonyl group in L keeps its character and does not affect the Ru(II) moieties. In addition, the two Ru(II) terminuses of the dinuclear complex have no interaction through the bridging linkage.

A novel tripodal ligand, tris[(4'-methyl-2,2'-bipyridyl-4-yl)methyl]carbinol (L), has been synthesized. The spectroscopic, electrochemical, and photocatalytic properties of the new trinuclear complexes (Ru(2)Re and RuRe(2)) linked by the tripodal bridging ligand L are then investigated. In addition, 2-fold-improved photocatalytic activities were obtained in the case of these trinuclear complexes compared to the mixtures of the appropriate monometallic model complexes in the reduction of CO(2) under visible irradiation.

In the excited state of the covalently bridged Ru(II)/Os(II) binuclear complex, [BTFMB2Ru(II)MebpyCH2CH(OH)CH2MebpyOs(II)(bpy)2] (BTFMB = 4,4'-bis-trifluoromethyl-2,2'-bipyridine), 1 , a nearly complete quenching of Ru11→π* (BTFMB) MLCT emission was observed at room temperature. Lifetime measurements were performed to evaluate the quenching rate and the mechanism on a quantitative basis. In methanol at 298 K, the rate of reductive quenching of *Ru(II) by Os(II) (kel) is 5.3 × 108 s−1 and the rate of energy transfer from *Ru(II) to Os(II) (ken) is 7.8 × 107 s−1. In n-butanol both processes are competitive. Values of kel and ken are 1.8 × 108 s−1 and 1.7 × 108 s−1, respectively. It is shown that the relaxation dynamics of solvent plays an important role in the intramolecular electron-transfer process in protic media even when the observed rate is slow with respect to the solvent motion. The dipole-dipole interaction (Forster mechanism) is proposed for the energy-transfer mechanism.

The synthesis of the novel bidentate ligands 4,4'-bis(trifluoromethyl)-2,2'-bipyridine (4,4'-BTFMB), 5,5'- bis-(trifluoromethyl)-2,2'-bipyridine (5,5'-BTFMB), and 4,4',5,5'-tetrakis(trifluoromethyl)-2,2'-bipyridine (4,4',5,5'-TTFMB) is reported. The photophysical and photochemical properties of a series of tris-chelate complexes [Ru(bpy) n (BTFMB) 3-n ] 2+ (n=0-2; bpy=2,2'-bipyridine) are described.

A novel series of covalently-linked polypyridine Re(I)/Ru(II) binuclear complexes [LRe(I)(CO)3MebpyCH2CH(OH)CH2MebpyRu(II)(bpy)2] (L = Cl, 4-methylpyridine, N-methylimidazole, or acetonitrile) 1, has been synthesized. The emission spectra of 1 (excitation wavelength: 360 nm) showed a nearly complete quenching of ReI→π*(bpy) MLCT emission and the enhancement of RuII→π*(bpy) MLCT emission. The rate constants (ken) of the intramolecular energy transfer ranged from 1.7 × 108 to 1.2 × 109 s−1. The relation between ken and the energy gap was discussed in terms of the energy gap law.

Ru(II)bpy2Mebpy-CH2CH(OH)CH2-MebpyRh(III)L2 (L = bpy. phen) (1) were newly synthesized. Intramolecular electron-transfer in excited 1 was studied with a time-correlated single photon counting method. In H2O, the excited Ru(II) complex exhibits a biexponential decay. The presence of a slow component suggests that the excited state can be repopulated by thermal activation from the Ru(III)–Rh(II) and the direct process to the ground state lies in the Marcus Inverted region.

We study the electrochemical, spectroscopic, and photocatalytic properties of a series of Ru(II)-Re(I) binuclear complexes linked by bridging ligands 1,3-bis(4'-methyl-[2,2']bipyridinyl-4-yl)propan-2-ol (bpyC3bpy) and 4-methyl-4'-[1,10]phenanthroline-[5,6-d]imidazol-2-yl)bipyridine (mfibpy) and a tetranuclear complex in which three [Re(CO)3Cl] moieties are coordinated to the central Ru using the bpyC3bpy ligands. In the bpyC3bpy binuclear complexes, 4,4'-dimethyl-2,2'-bipyridine (dmb) and 4,4'-bis(trifluoromethyl)-2,2'-bipyridine ({CF3}2bpy), as well as 2,2'-bipyridine (bpy), were used as peripheral ligands on the Ru moiety. Greatly improved photocatalytic activities were obtained only in the cases of [Ru{bpyC3bpyRe(CO)3Cl}3]2+ (RuRe3) and the binuclear complex [(dmb)2Ru(bpyC3bpy)Re(CO)3Cl]2+ (d2Ru-Re), while photocatalytic responses were extended further into the visible region. The excited state of ruthenium in all Ru-Re complexes was efficiently quenched by 1-benzyl-1,4-dihydronicotinamide (BNAH). Following reductive quenching in the case of d2Ru-Re, generation of the one-electron-reduced (OER) species, for which the added electron resides on the Ru-bound bpy end of the bridging ligand bpyC3bpy, was confirmed by transient absorption spectroscopy. The reduced Re moiety was produced via a relatively slow intramolecular electron transfer, from the reduced Ru-bound bpy to the Re site, occurring at an exchange rate (DeltaG approximately 0). Electron transfer need not be rapid, since the rate-determining process is reduction of CO2 with the OER species of the Re site. Comparison of these results with those for other bimetallic systems gives us more general architectural pointers for constructing supramolecular photocatalysts for CO2 reduction.

The synthesis of the novel bidentate ligands 4,4'-bis(trifluoromethyl)-2,2'-bipyridine (4,4'-BTFMB), 5,5'- bis-(trifluoromethyl)-2,2'-bipyridine (5,5'-BTFMB), and 4,4',5,5'-tetrakis(trifluoromethyl)-2,2'-bipyridine (4,4',5,5'-TTFMB) is reported. The photophysical and photochemical properties of a series of tris-chelate complexes [Ru(bpy) n (BTFMB) 3-n ] 2+ (n=0-2; bpy=2,2'-bipyridine) are described.

A condensation polymer (β-CD-E) of β-CD with epichlorohydrin was compared with β-CD and poly(β-CD acrylate) in regard to inclusion behavior in an aqueous solution. The stability of the inclusion complexes of β-CD-E with substrates of a single guest part is smaller than that of β-CD because of steric hindrance by substituents on β-CD. On the other hand, the stability of β-CD-E complexes for substrates with two guest parts is much larger than that of β-CD and is somewhat smaller than that of poly(β-CD acrylate). This is due to the cooperation in binding of the adjacent two CD units on a polymer chain.

The exciplex formation in 9-vinylphenanthrene-p-N,N-dimethylaminostyrene copolymers, its characteristics, and the electron transfer process in polar solvents were studied. The copolymer exhibited a more intense intramolecular exciplex fluorescence than the low-molecular-weight model system, phenanthrene-N,N-dimethylaniline, in which the intermolecular exciplex formation occurred. Intensities of the exciplex fluorescence, which were unchanged regardless of the copolymer composition, led us to speculate that the efficient energy migration takes place from an excited phenanthrene unit to an exciplex forming site on the polymer chain. The electron transfer in the copolymer-p-dicyanobenzene system was studied in polar media. The formation of p-dicyanobenzene anion radical was measured by flash photolysis and electron spin resonance (ESR). p-Dicyanobenzene anion radical was generated by the electron transfer process via exciplex and the direct electron transfer process from the excited phenanthrene unit in the copolymer.

Studies have been made on the exciplex formation in a vinyl copolymer, its characteristics, and the electron-transfer process in polar solvents using a p-N,N-dimethylaminostyrene-p-cyanostyrene copolymer. The copolymer was found to exhibit a much more intense intramolecular exciplex fluorescence than the model N,N-dimethylaniline–cyanobenzene system where the intermolecular exciplex formation occurs. The copolymer system has an advantage over the model system in the exciplex formation process but suffers a disadvantage in the process of ionic dissociation in polar solvents. The ionic dissociation for the copolymer system, however, was attained in the presence of a stronger electron acceptor, p-dicyanobenzene, in polar solvents. The results of flash photolysis and exciplex quenching indicated that the p-dicyanobenzene, anion radical was generated by successive electron transfer from the cyanobenzene anion radical portion in the copolymer to p-dicyanobenzene. That is, in the copolymer system, the interaction between the pendant donor and acceptor groups is favored even in the presence of a stronger electron acceptor.

Crosslinked α- and β-cyclodextrin gels (α-CD-E and β-CD-E) were used for the chromatographic resolution of racemic mandelic acid and its derivatives. β-CD-E bound L-(+)-isomers preferentially over D-(−)-isomers and resolved DL-methyl mandelate to give a D-(−)-isomer of 100% optical purity in the first fraction. Mandelic acid, ethyl mandelate, and O-methylated mandelic acid yielded resolutions of 65–83% in initial fractions. α-CD-E, on the contrary, bound D-(−)-isomers more strongly than L-(+)-isomers, resolving DL-methyl mandelate to a smaller extent than β-CD-E. Binding of DL-mandelic acid and DL-methyl mandelate on β-CD-E was studied quantitatively by the equilibrium method. β-CD-E has a similar binding capacity to starch with 1:1 stoichiometry but bound much more strongly than starch. β-CD-E has the same mode of selectivity as starch for the asymmetric binding of the mandelic acid derivatives, but α-CD-E has a reverse selectivity to β-CD-E and starch.

— Quenching of excited state of Ru(bpy)2(poly-4-methyl-4'-vinyl-2,2'-bipyridine)Cl2 by sodium anthraquinone-2-sulfonate was found to be a static process. The quenching was interpreted by application of a modified Perrin model. Radius of the quenching sphere was estimated to correspond to 6.65 monomer units and was unchanged on varying the Ru2+ content of the polymer. Energy migration along the polymer chain was denied.

In the photoreduction of the newly synthesized methyl viologen dimer,1′,1″-trimethylene-bis(1-methyl-4,4′-bipyridinium) perchlorate, by 2-propanol, the exclusive formation of the stable radical cation dimer at room temperature was observed, which gave an unequivocal evidence for the intramolecular process.

The formation of charge-transfer complexes of poly(N-methyl-3-vinylcarbazole (P3VCA) with tetracyanoethylene (TCNE), 2,4,5,7-tetranitro-9-fluorenone (TeNF), chloranil (p-CA), and 1,3,5-trinitrobenzene (TNB) was investigated spectrophotometrically. The association constants (K) of P3VCA complexes were 2.5 to 7.1 times larger than those of the corresponding monomeric analog, N-methyl-3-ethyl-carbazole. To clarify the polymer effect, copolymers of N-methyl-3-vinylcarbazole with styrene and with the dimer model, 1,3-bis[3-(N-methylcarbazolyl)]propane, were studied to obtain the details of the complex formation. The complex of the dimer model was found to be less stable than those of the monomer analog and P3VCA. It is suggested that large stabilities in the polymer system do not simply result from the local concentration effect, but also from the favorable arrangements of the neighboring carbazole units.

Covalently linked dimers of Ru(bpy)3 2+ (3 and 4) connected by two or three carbon atoms were synthesized as models for Ru(bpy)3 2+-containing vinyl polymer (1). The luminescence properties of 3 and 4 were compared with those of its component monomer, 4,4′-dimethyl-2,2′-bipyridine-bis(2,2′-bipyridine)ruthenium(II) complex (2). In excited 3 and 4, intramolecular interaction leading to enhanced quenching was not observed. Electron-transfer quenching of the excited dimer with methylviologen (MV2+) and the zwitterionic viologen, 1,1′-bis(3-sulfopropyl)4,4′-bipyridinium (SPV), was studied and compared with that of 1 and 2. The low quenching efficiency in 1, 3, and 4 systems can be ascribed to the steric hindrance of unexcited ruthenium complex. Energy migration between ruthenium complexes in the excited 1, 3, and 4 can be ruled out from the kinetic evidence.

In order to study the polymer effect in the photoreduction of viologen-containing polymers by 2-propanol, bisviologen compounds, V2+–(CH2)n–V2+, were subjected to photoreduction. The rates of photoreduction occur in the order n=2>3>4>5>MV2+. The structure of the photoreduced species was found to be predominantly the doubly reduced species, V+–(CH2)n–V+, in the cases of n=2 and 3, and mixtures of the doubly reduced and singly reduced species, V+–(CH2)n–V2+, in the cases of n=4 and 5. Intramolecular dimeric association of V+ units was observed for all the compounds except for n=2, where the intramolecular association was structurally inhibited. The variation of rate and structure distribution of reduced species was interpreted in terms of the local concentration effect in the photoreduction step.

The emission properties of 1-(4-dimethylaminophenyl)-3-(9-phenanthryl)propane, Ph(CH2)3 DMA, and 1,3-di-(9-phenanthyrl)propane, Ph(CH2)3Ph, were studied in comparison with those of poly(9-vinylphenanthrene-co-p-N,N-dimethylaminostyrene). Ph(CH2)3DMA showed an intense intramolecular exciplex fluorescence in dioxane. Ph(CH2)3Ph did not exhibit a clear intramolecular excimer fluorescence. The quenching of the intramolecular exciplex by several electron acceptors was studied. As a result moderate electron acceptors, such as cyanobenzene, methyl benzoate, and acrylonitrile, selectively quenched the intramolecular exciplex, and in the case of cyanobenzene the subsequent formation of another fluorescent exciplex was observed. The results were discussed in terms of the reduction potentials of electron accepting quenchers.

Ruthenium (II) complex-containing polymers were prepared and characterized by absorption and luminescence spectra, luminescence quantum yield, and luminescence lifetime. The polymers are Ru(bpy)2(poly-6-vinyl-2,′2-bipyridine)CI2 (1) and Ru(bpy)2(poly-4-methyl-4′-methyl-4′ -vinyl-2,2′-bipyridine)CI2 (2). The absorption spectra and luminescence spectra of polymers 1 and 2 were substantially the same as that of Ru(bpy)3CI2. The lifetime of polymers 1 and 2 was similar to that of the respective monomer model compounds. The lifetime of polymer 1 was very short (ca. 13 ns) in comparison to Ru(bpy)3CI2 (660 ns), whereas the lifetime of polymer 2 (660 ns) was similar to that of Ru(bpy)3CI2. The temperature-dependency of the lifetime was discussed in terms of Watts' model.

In order to study the role of viologen-containing vinyl polymers in light energy conversion systems, the photoreduction of the polymer by 2-propanol and the properties of the reduced polymer were studied in comparison with methylviologen. There were marked polymer effects in the initial rate of photoreduction as well as in the absorption spectra of the photoreduced species. Both effects were interpreted in terms of the local concentration effect of viologen units in the photoreduction step. The spectral difference was found to be due to the dimeric association of the reduced viologen units on the polymer.

Treatment of tetrakis(tetramethylethylenedioxyboryl)methane, (Me4C2 - O2B)4C, in THF with butyllithium at −78° generates the tris(tetramethylethylenedioxyboryl)methide ion, (Me4C2O2B)3C−, which reacts with chlorotrimethylsilane at −78° to form trichlorosilyltris(tetramethylethylenedioxyboryl)-methane, (Me4C2O2B)3CSiMe3. The yield was low, but other attempts to form silyltriborylmethanes have failed altogether. The ion (Me4C2O2B)3C− reacts with tetraphenylcyclopentadienone at −78° to form the expected fulvene, 1,1-bis-(tetramethylethylenedioxyboryl)-2,3,4,5-tetraphenylfulvene. The red color of the tetraphenylcyclopentadienone is converted immediately to the brown of the fulvene product, indicating that the β-elimination of boron and oxygen occurs rapidly under basic conditions at −78°.

Dimers containing /?-cyclodextrin (/?-CD) moieties at both ends of dicarboxylic acids were prepared by the reaction of bis(m-nitrophenyl) dicarboxylate with a large excess of ft-CD, and were purified by dialysis and gel chromatography. The interaction of the dimers with potassium 2-p-toluidinylnaphthalene-6-sulfonate (TNS) was studied by the fluorescence technique and compared with that of /?-CD and poly(acryloyl-/?-CD). The dimers were found to bring about a much greater enhancement and blue shift of the TNS fluorescence than /?-CD but less than the polymer. The succinate dimer enhanced the TNS fluorescence twofold more than the glutarate dimer. Dissociation constants and stoichiometries were determined by fluorometric titration and continuous variation methods. The dimer complexes showed exclusively 2 : 1 stoichiometry (CD : TNS), even in the concentration range in which /?-CD showed 1 : 1 stoichiometry. The 2 : 1 complexes of the dimers were much more stable than the 2 : 1 complex of fi-CD and were comparable to that of the polymer. Thus, two CD units linked by the chain were found to cooperate in binding one TNS molecule.

Proprietes photochimiques de Ru(bpy) 2 (polymethyl-4 vinyl-4' bipyridine-2,2')Cl 2 et comparaison avec celles de Ru(bpy) 3 Cl 2

In the electron-transfer reaction from the fluorescent intramolecular exciplexes of a copolymer containing phenanthrene and N,N-dimethylaniline moieties, and of a model compound to electron acceptors, the reactivity of the exciplexes was studied kinetically in polar and nonpolar media. The copolymer was poly(9-vinylphenanthrene-co-p-dimethylaminostyrene) and the model compound was N,N-dimethyl-4-[3-(9-phenanthryl)propyl]aniline. The oxidation potential of the exciplex was evaluated by the relation of the exciplex-quenching rate constants to the reduction potentials of electron-accepting quenchers according to the equations of Rehm and Weller. It was found that the electron-donating ability of these intramolecular exciplexes resembled with each other and was larger than that of excited phenanthrene. In polar media the donating ability was very close to that of the phenanthrene anion radical.

ジメチルジビニロキシシランは炭素同族体と同様に次のようにラジカル開始剤により, 5員環, 6員環, 未反応ビニロキシ基からなる環化重合体を与える。モノマー濃度の減少に伴い, 分子内環化反応の割合は増加し, 環化反応に対する温度依存性より求めた, 5員環, 6員環生成の活性化エネルギーの差, および頻度因子の比はEc5-Ec6=2kcal/mol, Ac6/Ac5=0.7×10102であった。このポリマーは加溶媒分解で容易にPVAに誘導することができ5員環からは1, 2-グリコール結合が生成する。このようにして得られた1, 2-グリコール結合を30mol%含むPVAは通常のPVAと異なるIRスペクトルを800～1200cm-1の領域で示す。特に1090cm-1のνc-oの吸収は1060cm-1に移動する。立体規則性を知る目的でポリ酢酸ビニルに誘導しそのNMRスペクトルを検討したが, 1, 2-グリコールの存在による分解能の低下で明確な知見は得られなかった。

内部オレフィンであるRHC=CHR, R2C=HR, R2C=CR2 (R=CH3, またはCl) をカルベン反応を用いてシクロプロパン誘導体としその重合性を検討した。ラジカル重合ではメチル置換シクロプロパンの単独重合, 無水マレイン酸との共重合は認められなかった。塩素置換シクロプロパンもスチレンと共重合を行なわない。カチオン重合では一部の塩素置換体は開環せずに脱塩化水素による3員環構造を骨核にもつポリマーを与えた。メチル置換体は開環重合物を生成するが, 開環の場所が一定していないと考えられる。アニオン重合はほとんど認められなかった。モノマー合成の過程で一部の塩素置換体が熱異性化することが認められたので熱重合の可能性もあわせて検討する意味で熱分解を行ない、一部のものがオレフィンに異性化した。ペンタクロルシクロプロパンはオレフィンを経て熱分解し, ヘキサクロルベンゼンを生成した。