Ultrafast nonadiabatic dynamics of [Fe(II)(bpy)(3)](2+) in solution

The ultrafast relaxation of aqueous iron(II)-tris(bipyridine) upon excitation into the singlet metal-to-ligand charge-transfer band (1MLCT) has been characterized by femtosecond fluorescence up-conversion and transient absorption (TA) studies. The fluorescence experiment shows a very short-lived broad 1MLCT emission band at approximately 600 nm, which decays in < or =20 fs, and a weak emission at approximately 660 nm, which we attribute to the 3MLCT, populated by intersystem crossing (ISC) from the 1MLCT state. The TA studies show a short-lived (<150 fs) excited-state absorption (ESA) below 400 nm, and a longer-lived one above 550 nm, along with the ground-state bleach (GSB). We identify the short-lived ESA as being due to the 3MLCT state. The long-lived ESA decay and the GSB recovery occur on the time scale of the lowest excited high-spin quintet state 5T2 lifetime. A singular value decomposition and a global analysis of the TA data, based on a sequential relaxation model, reveal three characteristic time scales: 120 fs, 960 fs, and 665 ps. The first is the decay of the 3MLCT, the second is identified as the population time of the 5T2 state, while the third is its decay time to the ground state. The anomalously high ISC rate is identical in [RuII(bpy)3]2+ and is therefore independent of the spin-orbit constant of the metal atom. To reconcile these rates with the regular quasi-harmonic vibrational progression of the 1MLCT absorption, we propose a simple model of avoided crossings between singlet and triplet potential curves, induced by the strong spin-orbit interaction. The subsequent relaxation steps down to the 5T2 state dissipate approximately 2000 cm-1/100 fs. This rate is discussed, and we conclude that it nevertheless can be described by the Fermi golden rule, despite its high value.     

Stability of [Ru(II)(tpy)(bpy)(OH(2))](2+)-modified graphite electrodes during indirect electrolyses

The stability of a graphite felt electrode modified by covalent attachment of [Ru(II)(tpy)(bpy)(OH(2))](2+) is investigated during the indirect electrolyses of alcohols in a flow cell. The continuous increase of the local potential of the electrode during the electrolyses attests to its degradation. Cyclic voltammetry analyses of the modified electrode after electrolyses show a total decrease of 80-90% of the wave corresponding to the Ru(III/II) couple. The concentration of remaining alcohol measured at the outlet of the cell is almost constant during all the electrolyses but increase when the potential exceeds 0.95 V(SCE). At low potentials, the electrode can be regenerated by reaction with Ru(II)Cl(2)(DMSO)(tpy) and then CF(3)SO(3)H, followed by hydrolysis, showing that the bipyridine ligand remains covalently attached to the electrode. At high potentials, the graphite is oxidized and the catalyst is partly lost in the reaction medium. XPS analyses of Ru core levels reveal that the ruthenium disappeared after electrolysis, showing that the degradation of the modified electrode is due to the demetalation of the oxidized complex.     

Reactions of [Ru(H(2)O)(6)](2+) with water-soluble tertiary phosphines

In aqueous solutions under mild conditions, [Ru(H(2)O)(6)](2+) was reacted with various water-soluble tertiary phosphines. As determined by multinuclear NMR spectroscopy, reactions with the sulfonated arylphosphines L =mtppms, ptppms and mtppts yielded only the mono- and bisphosphine complexes, [Ru(H(2)O)(5)L](2+), cis-[Ru(H(2)O)(4)L(2)](2+), and trans-[Ru(H(2)O)(4)L(2)](2+) even in a high ligand excess. With the small aliphatic phosphine L = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1(3,7)]decane (pta) at [L]:[Ru]= 12:1, the tris- and tetrakisphosphino species, [Ru(H(2)O)(3)(pta)(3)](2+), [Ru(H(2)O)(2)(pta)(4)](2+), [Ru(H(2)O)(OH)(pta)(4)](+), and [Ru(OH)(2)(pta)(4)] were also detected, albeit in minor quantities. These results have significance for the in situ preparation of Ru(II)-tertiary phosphine catalysts. The structures of the complexes trans-[Ru(H(2)O)(4)(ptaMe)(2)](tos)(4)x2H(2)O, trans-[Ru(H(2)O)(4)(ptaH)(2)](tos)(4)[middle dot]2H(2)O, and trans-mer-[RuI(2)(H(2)O)(ptaMe)(3)]I(3)x2H(2)O, containing protonated or methylated pta ligands (ptaH and ptaMe, respectively) were determined by single crystal X-ray diffraction.     

Study on the Interactions of Ruthenium(III), Rhodium(III) and Palladium(II) Ions with DNA

Fluorescence, absorption and circular dichroism spectra have been used in the interactions of ruthenium(III), rhodium(III) and palladium(II) ions with DNA with berberine as a probe (berberine, Scheme 1). The results are as follows: ruthenium(III) and rhodium(III) ions show different effects from that of the palladium(II) ion on the fluorescence spectra characteristics of berberine-DNA system. Quenching fluorescence is seen with palladium(II) ion addition, whereas increasing fluorescence is observed for ruthenium(III) and rhodium(III) ions. The addition of ruthenium(III), rhodium(III) and palladium(II) ions causes the increasing absorption of the DNA solution. The addition of ruthenium(III), rhodium(III) and palladium(II) ions to the DNA solution also causes the circular dichroism spectra to change. The above results suggest that different metal ions exhibit different affinity when binding to DNA, which could correlate well with the ions’ charge, structure and the ability to coordinate. There is a comparison between Pt(IV) and Pd(II) ions on the fluorescence of the berberine-DNA system.     

Targeting large phosp(III)azane macrocyles [{P(mu-NR)}(2)(LL)](n) (n> or = 2)

The condensation reactions of the dimer [ClP(micro-NR)](2) with organic diacids [LL(H)(2)], possessing linear orientations of their organic groups, result in the formation of phospha(III)zane macrocyles of the type [{P(mu-NR)}(2)(LL)](n) of various sizes. The series of macrocycles [{P(mu-N(t)Bu)}(2){1,5-(NH)(2)C(10)H(6)}](3), [{P(mu-NCy)}(2)(1,5-O(2)C(10)H(6))](n) [n = 3; n = 4], [{P(mu-N(t)Bu)}(2){1,4-(NH)(2)C(6)H(4)}](4), [{P(mu-N(t)Bu)}(2)(1,4-O(2)C(6)H(4))], [{P(mu-NCy)}(2)(1,4-O(2)C(6)H(4))](3) and [{P(mu-N(t)Bu)}(2){(NH)C(6)H(4)OC(6)H(4)(NH)}](2) can be related to classical organic frameworks, like calixarenes.     

Electrochemiluminescent behavior of allopurinol in the presence of Ru(bpy)(3)(2+)

The electrochemiluminescent (ECL) response of allopurinol was studied in aqueous media over a wide pH range (pH 2–13) using flow injection (FI) analysis. It was revealed that allopurinol itself had no ECL activity, but could greatly enhance the ECL of Ru(bpy)₃²⁺ in alkaline media giving rise to a sensitive FI-ECL response. The effects of experimental conditions including the mode of applied voltage signal, the potential of working electrode, pH value, the flow rate of carrier solution, and the concentration of Ru(bpy)₃²⁺ and allopurinol on the ECL intensity were investigated in detail. The most sensitive FI-ECL response of allopurinol was found at pH 12.0, where the FIA-ECL intensity showed a linear relationship with concentration of allopurinol in the range 1 × 10⁻⁸ mol L⁻¹ to 5 × 10⁻⁷ mol L⁻¹, and the detection limit was 5 × 10⁻⁹ mol L⁻¹.     

Direct measurement of excited-state intervalence transfer in [(tpy)Ru(III)(tppz(*-))Ru(II)(tpy)](4+) by time-resolved near-infrared spectroscopy

Extension of time-resolved infrared (TRIR) measurements into the near-infrared region has allowed the first direct measurement of a mixed-valence band in the metal-to-ligand charge transfer (MLCT) excited state of a symmetrical ligand-bridged complex. Visible laser flash excitation of [(tpy)Ru(tppz)Ru(tpy)]4+ (tppz is 2,3,5,6-tetrakis(2-pyridyl)pyrazine; tpy is 2,2':6',6' '-terpyridine) produces the mixed-valence, MLCT excited state [(tpy)RuIII(tppz*-)RuII(tpy)]4+* with the excited electron localized on the bridging tppz ligand. A mixed-valence band appears at numax = 6300 cm-1 with a bandwidth-at-half- maximum, Deltanu1/2 = 1070 cm-1. In the analogous ground-state complex, [(tpy)Ru(tppz)Ru(tpy)]5+, a mixed-valence band appears at numax = 6550 cm-1 with Deltanu1/2 = 970 cm-1 which allows a comparison to be made of electronic coupling across tppz0 and tppz*- as bridging ligands.     

Near‐IR Phosphorescent Ruthenium(II) and Iridium(III) Perylene Bisimide Metal Complexes

The phosphorescence emission of perylene bisimide derivatives has been rarely reported. Two novel ruthenium(II) and iridium(III) complexes of an azabenz‐annulated perylene bisimide (ab‐PBI), [Ru(bpy)₂(ab‐PBI)][PF₆]₂ 1 and [Cp*Ir(ab‐PBI)Cl]PF₆ 2 are now presented that both show NIR phosphorescence between 750–1000 nm in solution at room temperature. For an NIR emitter, the ruthenium complex 1 displays an unusually high quantum yield (Φ_p) of 11 % with a lifetime (τ_p) of 4.2 μs, while iridium complex 2 exhibits Φ_p<1 % and τ_p=33 μs. 1 and 2 are the first PBI‐metal complexes in which the spin–orbit coupling is strong enough to facilitate not only the S_n→T_n intersystem crossing of the PBI dye, but also the radiative T₁→S₀ transition, that is, phosphorescence.     

Copper and Bismuth Complexes Containing Dipyridyl gem-Diolato Ligands: Bi(III)(2)[(2-Py)(2)CO(OH)](2)(O(2)CCF(3))(4)(THF)(2), Cu(II)[(2-Py)(2)CO(OH)](2)(HO(2)CCH(3))(2), and Cu(II)(4)[(2-Py)(2)CO(OH)](2)(O(2)CCH(3))(6)(H(2)O)(2), a Ferromagnetically Coupled Tetranuclear Copper(II) Chain

The reactions of the singly deprotonated di-2-pyridylmethanediol ligand (dpmdH(-)) with copper(II) and bismuth(III) have been investigated. A new dinuclear bismuth(III) complex Bi(2)(dpmdH)(2)(O(2)CCF(3))(4)(THF)(2), 1, has been obtained by the reaction of BiPh(3) with di-2-pyridyl ketone in the presence of HO(2)CCF(3) in tetrahydrofuran (THF). The reaction of Cu(OCH(3))(2) with di-2-pyridyl ketone, H(2)O, and acetic acid in a 1:2:2:2 ratio yielded a mononuclear complex Cu[(2-Py)(2)CO(OH)](2)(HO(2)CCH(3))(2), 2, while the reaction of Cu(OAC)(2)(H(2)O) with di-2-pyridyl ketone and acetic acid in a 2:1:1 ratio yielded a tetranuclear complex Cu(4)[(2-Py)(2)CO(OH)](2)(O(2)CCH(3))(6)(H(2)O)(2), 3. The structures of these complexes were determined by single-crystal X-ray diffraction analyses. Three different bonding modes of the dpmdH(-) ligand were observed in compounds 1-3. In 2, the dpmdH(-) ligand functions as a tridentate chelate to the copper center and forms a hydrogen bond between the OH group and the noncoordinating HO(2)CCH(3) molecule. In 1 and 3, the dpmdH(-) ligand functions as a bridging ligand to two metal centers through the oxygen atom. The two pyridyl groups of the dpmdH(-) ligand are bound to one bismuth(III) center in 1, while in 3 they are bound two copper(II) centers, respectively. Compound 3 has an unusual one dimensional hydrogen bonded extended structure. The intramolecular magnetic interaction in 3 has been found to be dominated by ferromagnetism. Crystal data: 1, C(38)H(34)N(4)O(14)F(12)Bi(2), triclinic P&onemacr;, a = 11.764(3) ?, b = 11.949(3) ?, c = 9.737(1) ?, alpha =101.36(2) degrees, beta = 105.64(2) degrees, gamma = 63.79(2) degrees, Z = 1; 2, C(26)H(26)N(4)O(8)Cu/CH(2)Cl(2), monoclinic C2/c, a = 25.51(3) ?, b = 7.861(7) ?, c = 16.24(2) ?, beta = 113.08(9) degrees, Z = 4; 3, C(34)H(40)N(4)O(18)Cu(4)/CH(2)Cl(2), triclinic P&onemacr;, a = 10.494(2) ?, b = 13.885(2) ?, c = 7.900(4) ?, alpha =106.52(2) degrees, beta = 90.85(3) degrees, gamma = 94.12(1) degrees, Z = 1.     

Synthesis and Structure of the Ruthenium(II) Complexes [(eta-C(5)Me(5))Ru(NO)(bipy)](2+) and [(eta-C(5)Me(5))Ru(NO)(dppz)](2+). DNA Cleavage by an Organometallic dppz Complex (bipy = 2,2'-Bipyridine; dppz = Dipyrido[3,2-a:2',3'-c]phenazine)

The salts [(eta-C(5)Me(5))Ru(NO)(bipy)][OTf](2) (1[OTf](2)) and [(eta-C(5)Me(5))Ru(NO)(dppz)][OTf](2) (2[OTf](2)) are obtained from the treatment of (eta-C(5)Me(5))Ru(NO)(OTf)(2) with 2,2'-bipyridine (bipy) or dipyrido[3,2-a:2',3'-c]phenazine (dppz) (OTf = OSO(2)CF(3)). X-ray data for 1[OTf](2): monoclinic space group P2(1)/c, a = 11.553 (4) ?, b = 16.517 (5) ?, c = 14.719 (4) ?, beta = 94.01 (2) degrees, V = 2802 (2) ?(3), Z = 4, R1 = 0.0698. X-ray data for 2[OTf](2): monoclinic space group P2(1)/c, a = 8.911 (2) ?, b = 30.516 (5) ?, c = 24.622 (4) ?, beta = 99.02 (1) degrees, V = 6613 (2) ?(3), Z = 8, R1 = 0.0789. Both 1[OTf](2) and 2[OTf](2) are soluble in water where they exhibit irreversible electrochemical oxidation and reduction. A fluorescence-monitored titration of a DNA solution containing 2[OTf](2) with ethidium bromide provides evidence that 2(2+) intercalates into DNA with a binding constant greater than 10(6) M(-)(1). DNA cleavage occurs when the DNA solutions containing 2[OTf](2) are photolyzed or treated with H(2)O(2) or K(2)S(2)O(8).     

联吡啶和邻菲咯啉混配的钌配合物的核磁共振氢谱分析

合成了Ru(bpy)2(phen)(PF6)2 和Ru(bpy)(phen)2(PF6)2 (bpy和phen分别为2,2′-联吡啶和1,10 -邻菲咯啉)两种电化学发光物质,以 1HNMR谱研究这两种配合物的立体结构,利用 1H - 1HCOSY(同核相关谱)核磁共振技术详细分析并归属了它们的氢谱峰。     

Complexes of (bpy)2Ru(II) and (Ph2bpy)2Ru(II) with a series of thienophenanthroline ligands: synthesis,characterization, and electronic spectra

A series of complexes (bpy)₂LRu(II) and (Ph₂bpy)₂LRu(II), where bpy is 2,2′-bipyridine, Ph₂bpy is 4,4′-diphenyl-2,2′-bipyridine and L is 1,10-phenanthroline (phen), [1]benzothieno[2,3-c][1,10]phenanthroline (btp), naphtho[1′,2′?:?5,4]thieno[2,3-c][1,10]phenanthroline [ntpl, l=linear], and naphtho[1′,2′?:?4,5]thieno[2,3-c][1,10]phenanthroline (ntph, h=helical) were synthesized and characterized using 2D COSY NMR spectra. The UV spectra were assigned to study their metal to ligand charge transfer (MLCT) excited states. Complexes of (bpy)₂LRu(II) showed identical absorption wavelengths (λ _max) for the MLCT of all four members of the series with the only variation being the intensity (log _ε ) for each. The MLCT of (Ph₂bpy)₂LRu(II) showed the similar behavior only with different wavelengths showing that in this heteroleptic series of complexes the MLCT is exclusively to the bpy ligands with none to thienophenanthroline (btp, ntpl, or ntph).     

Electronic modification of the [Ru(II)(tpy)(bpy)(OH(2))](2+) scaffold: effects on catalytic water oxidation

The mechanistic details of the Ce(IV)-driven oxidation of water mediated by a series of structurally related catalysts formulated as [Ru(tpy)(L)(OH(2))](2+) [L = 2,2'-bipyridine (bpy), 1; 4,4'-dimethoxy-2,2'-bipyridine (bpy-OMe), 2; 4,4'-dicarboxy-2,2'-bipyridine (bpy-CO(2)H), 3; tpy = 2,2';6',2'-terpyridine] is reported. Cyclic voltammetry shows that each of these complexes undergo three successive (proton-coupled) electron-transfer reactions to generate the [Ru(V)(tpy)(L)O](3+) ([Ru(V)=O](3+)) motif; the relative positions of each of these redox couples reflects the nature of the electron-donating or withdrawing character of the substituents on the bpy ligands. The first two (proton-coupled) electron-transfer reaction steps (k(1) and k(2)) were determined by stopped-flow spectroscopic techniques to be faster for 3 than 1 and 2. The addition of one (or more) equivalents of the terminal electron-acceptor, (NH(4))(2)[Ce(NO(3))(6)] (CAN), to the [Ru(IV)(tpy)(L)O](2+) ([Ru(IV)=O](2+)) forms of each of the catalysts, however, leads to divergent reaction pathways. The addition of 1 eq of CAN to the [Ru(IV)=O](2+) form of 2 generates [Ru(V)=O](3+) (k(3) = 3.7 M(-1) s(-1)), which, in turn, undergoes slow O-O bond formation with the substrate (k(O-O) = 3 × 10(-5) s(-1)). The minimal (or negligible) thermodynamic driving force for the reaction between the [Ru(IV)=O](2+) form of 1 or 3 and 1 eq of CAN results in slow reactivity, but the rate-determining step is assigned as the liberation of dioxygen from the [Ru(IV)-OO](2+) level under catalytic conditions for each complex. Complex 2, however, passes through the [Ru(V)-OO](3+) level prior to the rapid loss of dioxygen. Evidence for a competing reaction pathway is provided for 3, where the [Ru(V)=O](3+) and [Ru(III)-OH](2+) redox levels can be generated by disproportionation of the [Ru(IV)=O](2+) form of the catalyst (k(d) = 1.2 M(-1) s(-1)). An auxiliary reaction pathway involving the abstraction of an O-atom from CAN is also implicated during catalysis. The variability of reactivity for 1-3, including the position of the RDS and potential for O-atom transfer from the terminal oxidant, is confirmed to be intimately sensitive to electron density at the metal site through extensive kinetic and isotopic labeling experiments. This study outlines the need to strike a balance between the reactivity of the [Ru═O](z) unit and the accessibility of higher redox levels in pursuit of robust and reactive water oxidation catalysts.     

Palladium(II)-, Platin(II)-, Ruthenium(II)-, Rhodium(III)- und Iridium(III)-Komplexe von Desoxyfructosazin

Metal Complexes of Biologically Important Ligands. CIII. [1] Palladium(II), Platinum(II), Ruthenium(II), Rhodium(III), and Iridium(III) Complexes of Desoxyfructosazine The reactions of the pyrazine derivative desoxyfructosazin(pz) with K₂PtCl₄ and with the chlorobridged [M(PR₃)Cl₂]₂ (M = Pd, Pt), [(η⁵-C₅Me₅)MCl₂]₂ and [(η⁶-p-Cymol)RuCl₂]₂ give the watersoluble complexes cis-Cl₂Pt(pz)₂, (R₃P)(Cl)M(pz)M(Cl)(PR₃) (M = Pd, Pt), (η⁵-C₅Me₅)(Cl)₂M(pz)M(Cl)₂(η⁵-C₅Me₅) (M = Rh, Ir), (η⁶-p-Cymol)(Cl₂)Ru(pz)Ru(Cl)₂(η⁶-p-Cymol).     

Thiosemicarbazone Complexes of Ruthenium(II) and Rhodium(I) Containing Triphenylphosphine

Several new hexa-coordinated ruthenium(II) and penta-coordinated rhodium(I) complexes of the types [RuCl(CO)(PPh ₃ ) ₂ (TSC)], [RuH(CO)(PPh ₃ ) ₂ (TSC)], and [Rh(PPh ₃ ) ₃ (TSC)] (where TSC = anion of thiosemicarbazone Schiff bases) have been prepared by the reactions of [RuHCl(CO)(PPh ₃ ) ₃ ], [RuH ₂ (CO)(PPh ₃ ) ₃ )], and [RhH(PPh ₃ ) ₄ ] with thiosemicarbazones of 2-furaldehyde (H-FTSC), thiophene-2-carboxaldehyde (H-TCTSC), p-anisaldehyde (H-ATSC), piperonaldehyde (H-PTSC), and cyclohexanone (H-CTSC). All the new complexes obtained have been characterized on the basis of elemental analysis, IR, ¹ H NMR, ³¹ P NMR, and electronic spectral data.