Synthesis and luminescence behaviour of novel heterodecanuclear silver(I)-rhenium(I) alkynyl complexes. X-ray crystal structures of [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Me2bpy)(CO)3]4](PF6)2 and [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Br2phen)(CO)3]4](PF6)2

A novel series of luminescent heterodecanuclear mixed-metal alkynyl complexes, [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(N--N)(CO)3]4](PF6)2, (N--N = tBu2bpy, Me2bpy, phen, Br2phen), have been successfully synthesized; the X-ray crystal structures of [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Me2bpy)(CO)3]4](PF6)2 and [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Br2phen)(CO)3]4](PF6)2 have also been determined.     

Synthesis and reactivity of copper(I) complexes containing a bis(imidazolin-2-imine) pincer ligand

The new pincer ligand 2,6-bis[(1,3-di-tert-butylimidazolin-2-imino)methyl]pyridine (TL(tBu)) has been prepared in high yield from 2,6-bis(hydroxymethyl)pyridine (1) and 1,3-di-tert-butylimidazolin-2-imine (3). Reaction of TL(tBu) with [Cu(MeCN)4]PF6 affords the highly reactive copper(I) complex [(TL(tBu))Cu]PF6, [5]PF6, which forms the stable copper(I) isocyanide complexes [6a]PF6 (nu(CN) = 2179 cm(-1)) and [6b]PF6 (nu(CN) = 2140 cm(-1)) upon addition of tert-butyl or 2,6-dimethylphenyl isocyanide, respectively. For the cations 6a and 6b, DFT calculations reveal ground-state electronic structures of the type [(TL(tBu)-kappaN(1):kappaN(2))Cu(CNR)] with tricoordinate geometries around the copper atoms. Exposure of [5]PF6 to the air readily leads to trapping of atmospheric CO2 to form the square-planar complex [(TL(tBu))Cu(HCO3-kappaO)]PF6, [7]PF6, with the bicarbonate ligand adopting a rarely observed monodentate coordination mode. In chlorinated solvents such as dichloromethane or chloroform, [5]PF(6) rapidly abstracts chloride by reductive dechlorination of the solvent to yield [(TL(tBu))CuCl]PF6, [8]PF6 quantitatively. Reaction of TL(tBu) with copper(I) bromide or chloride affords complexes 9a and 9b, respectively, for which X-ray diffraction analysis, low-temperature NMR experiments and DFT calculations reveal the presence of a kappa(2)-coordinated ligand of the type [(TL(tBu)-kappaN(1):kappaN(2))CuX]. In solution, complex 9b undergoes slow disproportionation forming the mixed-valence copper(II)/copper(I) system [(TL(tBu))CuCl][CuCl2], [8]CuCl2 with a linear dichlorocuprate(I) counterion.     

一种新型含二茂铁基的多吡啶钌配合物与DNA的相互作用

利用金属配合物与DNA作用前后的光电性质变化探索大分子DNA的结构、构象、生物功能和作用机制之间的规律是无机化学前沿研究热点．Koepf等发现二氯二茂钛[(C6H5)2TiCl2]具有抗肿瘤活性,开创了金属茂类抗癌络合物研究的新领域,大量实验表明：金属茂类化合物不仅具有广泛的抗癌谱,     

Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes

We report a high yield, two-step synthesis of fac-[Ru(bpy)(CH3CN)3NO2]PF6 from the known complex [(p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). [(p-cym)Ru(bpy)NO2]PF6 is prepared by reacting [(p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from [(p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives [Ru(bpy)(CH3CN)3NO2]PF6. The new complexes [(p-cym)Ru(bpy)NO2]PF6 and fac-[Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of [Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes [Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), [Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared [Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes [Ru(bpy)TpNO][PF6]2 and [Ru(bpy)(Tpm)NO][PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for [Ru(bpy)TpNO][PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.     

A Ru(II) complex with 2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline: synthesis, characterization, and acid-base and DNA-binding properties

A new Ru(II) complex of [Ru(bpy)2(Hmspip)]Cl2 {in which bpy=2,2'-bipyridine, Hmspip=2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} have been synthesized and characterized. The ground- and excited-state acid-base properties of [Ru(bpy)2(Hmspip)]Cl2 and its parent complex of [Ru(bpy)2(Hpip)]Cl2 {Hpip=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline} have been studied by UV-visible (UV-vis) and emission spectrophotometric pH titrations. [Ru(bpy)2(Hmspip)]Cl2 acts as a calf thymus DNA intercalators with a binding constant of 4.0×10(5) M(-1) in buffered 50 mM NaCl, as evidenced by UV-vis and luminescence titrations, steady-state emission quenching by [Fe(CN)6]4-, DNA competitive binding with ethidium bromide, reverse salt titrations and viscosity measurements.     

钌配合物[Ru(bpy)2(PNT)]2+的合成、表征及与DNA相互作用研究

以cis-Ru(bpy)2Cl2·2H2O与PNT为原料合成钌(Ⅱ)多吡啶配合物[Ru(bpy)2(PNT)]2+(bpy=2,2’-联吡啶, PNT=2-[4’-(5-四唑基)苯基]咪唑-[4,5-f][1,10]邻菲咯啉), 通过元素分析、质谱和核磁共振波谱对该化合物进行了结构表征. 利用紫外-可见吸收光谱、荧光光谱、热变性和黏度实验研究了配合物与CT-DNA的相互作用, 实验结果表明, 该配合物以部分插入模式与DNA结合.     

Mixed ligand ruthenium(II) complexes of bis(pyrid-2-yl)-/bis(benzimidazol-2-yl)-dithioether and diimines: study of non-covalent DNA binding and cytotoxicity

A series of mixed ligand ruthenium(II) complexes [Ru(pdto)(diimine)](ClO4)2/(PF6)2 1-3 and [Ru(bbdo)(diimine)](ClO4), 4-6, where pdto is 1,8-bis(pyrid-2-yl)-3,6-dithiooctane, bbdo is 1,8-bis(benzimidazol-2-yl)-3,6-dithiooctane and diimine is 1,10-phenanthroline (phen), dipyrido-[3,2-d:2',3'-f]-quinoxaline (dpq) and dipyrido[3,2-a:2',3'-c]phenazine (dppz), have been isolated and characterised by analytical and spectral methods. The complexes [Ru(pdto)(phen)](PF6)2 la, [Ru(pdto)(dpq)(Cl](PF6) 2a, [Ru(bbdo)(phen)](PF6)2 4a and [Ru(bbdo)(dpq)](ClO4)2 5 have been structurally characterized and their coordination geometries around ruthenium(II) are described as distorted octahedral. In la, 4a and 5 the two thioether sulfur and two py/bzim nitrogen atoms of the tetradentate pdto/bbdo ligand are folded around Ru(II) to give predominantly a "cis-alpha" configuration. (I)H NMR spectral data of the complexes support this configuration in solution. In [Ru(pdto)(dpq)Cl](PF6) 2a with a distorted octahedral coordination geometry, one of the two py nitrogens of pdto is not coordinated. The DNA binding constants (Kb: 2, 2.00 +/- 0.02 x 10(4) M(-1), s = 1.0; 3, 3.00 +/- 0.01 x 10(6) M(-1), s = 1.3) determined by absorption spectral titrations of the complexes with CT DNA reveal that 3 interacts with DNA more tightly than 2 through partial intercalation of the extended planar ring of coordinated dppz with the DNA base stack. The DNA binding affinities of the complexes increase with increase in the number of planar aromatic rings in the co-ligand, and on replacing both the py moieties in pdto complexes (1-3) by bzim moieties to give bbdo complexes (4-6). Upon interaction with CT DNA the complexes 1, 2, 5 and 6 show a decrease in anodic current in the cyclic voltammograms. On the other hand, interestingly, 3 and 4 show an increase in anodic current suggesting their involvement in electrocatalytic guanine oxidation. Interestingly, of all the complexes, only 6 alters the superhelicity of DNA upon binding with supercoiled pBR322 DNA. The cytotoxicities of the dppz complexes 3 and 6, which avidly bind to DNA, have been examined by screening them against cell lines of different cancer origins. It is noteworthy that 6 exhibits selectivity with higher cytotoxicity against the melanoma cancer cell line (A375) than other cell lines, potency approximately twice that of cisplatin and toxicity to normal cells 3 and 90 times less than cisplatin and adriamycin respectively.     

Supramolecular assembly and solution properties of bis(bipyridyl)ruthenium(II) coordination complexes of aryl(2-pyridyl)methanones

A series of mono- and bis(2-pyridyl)-arylmethanone ligands were prepared by utilizing the reaction between either bromobenzonitrile or dicyanobenzene and 2-lithiopyridine in either a 1:1 or a 2:1 mol ratio, respectively. They react with [Ru(bpy)2(EtOH)2][PF6]2 to yield the new complexes [N,O-PhC(O)(2-py)Ru(bpy)2][PF6]2 (6), [p-N,O-BrC6H4C-(O)(2-py)Ru(bpy)2][PF6]2 (7), [m-N,O-BrC6H4C(O)(2-py)Ru(bpy)2][PF6]2 (8), [p-[N,O-C(O)(2-py)2Ru(bpy)2]2(C6H4)]-[PF6]4 (9), and [m-[N,O-C(O)(2-py)2Ru(bpy)2]2(C6H4)][PF6]4 (10). The solid state structures of 6 and 7 show that the octahedral cations are arranged in sinusoidal chains by pi-pi stacking and CH-pi interactions between bipyridyl groups. Substitution of bromine for hydrogen at the para position of the aryl group in 7 causes the aryl group to become involved in pi-pi stacking interactions that organize the chains into a sheet structure. The complicated 1H and 13C NMR spectra of the complexes have been fully assigned using 2D methods. The optical spectra show two absorption maxima near 434 and 564 nm due to MLCT transitions. The compounds were found to be nonluminescent. Electrochemical data acquired for CH3CN solutions of the bimetallic derivatives indicate that there is no electronic communication between metal centers mediated either through space or through ligand orbitals. Crystallographic information: 6.0.5CH3CN is monoclinic, C2/c, a = 24.3474(11) A, b = 13.7721(6) A, c = 21.3184(10) A, beta = 103.9920(10) degrees, Z = 8; 7 is monoclinic, P2(1)/c, a = 10.6639(11) A, b = 23.690(3) A, c = 13.7634(14) A, beta = 91.440(2) degrees, Z = 4.     

The pH-induced emission switching and interesting DNA-binding properties of a novel dinuclear ruthenium(II) complex

A novel dinuclear Ru(II) complex, [(bpy)(2)Ru(ebipcH(2))Ru(bpy)(2)](ClO(4))(4), where bpy = 2,2'-bipyridine and ebipcH(2) = N-ethyl-4,7-bis([1,10]-phenanthroline[5,6-f]imidazol-2-yl)carbazole, has been newly synthesized. The pH effects on UV-vis absorption and emission spectra of the complex are studied, and ground- and excited-state ionization constants of the complex are derived. The binding of the complex to calf thymus (ct) DNA is investigated with absorption and luminescence titrations, steady-state emission quenching, and viscosity measurements. The complex acts as a pH-induced "on-off" emission switch between pH 8.0 and pH 10.0 with a maximum on-off ratio of approximately 100 which is favorably compared with the other imidazole-containing Ru(II) complex congeners, and a strong ct-DNA intercalator with an intrinsic binding constant of 1.31(+/-0.08) x 10(6) M(-)(1) in buffered 50 mM NaCl.     

一种含芴基的钌(II)配合物的合成及DNA键合性质

合成了一种新的钌(II)配合物[Ru(bpy)2(Hfip)](ClO4)2, 其中bpy代表2,2′-联吡啶, Hfip代表2-(9H-芴-2-基)-1H-咪唑-[4,5-f]-[1,10]-邻菲啰啉. 通过紫外可见光谱、荧光光谱、稳态荧光淬灭、与溴化乙锭的竞争实验、粘度测量和DNA热变性研究了该配合物与小牛胸腺DNA的键合性质. 结果表明, 该配合物能嵌入键合DNA, 键合常数Kb=8.6×105 L·mol-1 (50 mmol·L-1 NaCl).     

Linear and star-shaped polynuclear Ru(II) complexes of 2-(2'-pyridyl)benzimidazolyl derivatives: syntheses, photophysical properties and red light-emitting devices

Two new star-shaped ligands with a 1,3,5-triphenylbenzene core, tmpb (1,3,5-tris[p-2-(2'-pyridyl)benzimidazolylphenyl]benzene), and a 2,4,6-tris(p-biphenyl)-1,3,5-triazine core, tmbt (2,4,6-tris[p-2-(2'-pyridyl)benzimidazolylbiphenyl]-1,3,5-triazine), have been synthesized. Their corresponding trinuclear Ru(II) complexes [Ru3(tmpb)(bpy)6](PF6)6 (3) and [Ru3(tmpt)(bpy)6](PF6)6 (4) have been obtained. Two dinuclear linear Ru(II) complexes with previously reported ligands bmb (1,4-bis[2-(2'-pyridyl)benzimidazolyl]benzene) and bmbp (4,4'-bis[2-(2'-pyridyl)benzimidazolyl]biphenyl) and formulae [Ru2(bmb)(bpy)4](PF6)4 (1) and [Ru2(bmbp)(bpy)4](PF6)4 (2) have also been synthesized. Photophysical and electrochemical properties of the new compounds have been investigated. All four compounds display a characteristic metal-to-ligand-charge transfer (MLCT) absorption band and emit a red light when excited at the maximum of the MLCT band with emission maximum at 624, 629, 623 and 625 nm, respectively in neat films at ambient temperature. The emission quantum efficiency of the four complexes in neat films was determined to be 0.15, 0.17, 0.04 and 0.05, respectively. Light emitting devices based on these four compounds were fabricated by spin-casting the compound as a neat film to an ITO substrate, followed by the deposition of an aluminium metal layer. All devices emit a deep red light and the device behavior resembles that of a light emitting electrochemical cell. The EL maximum of the devices 1, 2, 3, and 4 is at 637, 657, 678, and 655 nm, respectively. All four devices have a fast response time when a sufficiently high voltage is applied. The device based on 2 is the brightest with a maximum luminance of 133 cd m(-2) at 7 V. The performance of devices based on 1, 2, and 4 is in general much more efficient than the device based on [Ru(bpy)3](PF6)2, which was fabricated and evaluated under the same experimental conditions as for the devices based on 1-4.     

Systematic synthesis, isolation, and photophysical properties of linear-shaped Re(I) oligomers and polymers with 2-20 units

Systematic synthesis routes have been developed for the linear-shaped rhenium(I) oligomers and polymers bridged with bidentate phosphorus ligands, [Re(N--N)(CO)3-PP-{Re(N--N)(CO)2-PP-}(n)Re(N--N)(CO)3](PF6)(n+2) (N--N = diimine, PP = bidentate phosphine, n = 0-18). These were isolated by size exclusion chromatography (SEC) and identified by (1)H NMR, IR, electrospray ionization Fourier transform mass spectrometry, analytical SEC, and elemental analysis. Crystal structures of [Re(bpy)(CO)3-Ph2PC[triple bond]CPPh2-Re(bpy)(CO)3](PF6)2, [Re(bpy)(CO)3-Ph2PC[triple bond]CPPh2-Re(bpy)(CO)2-Ph2PC[triple bond]CPPh2-Re(bpy)(CO)3](PF6)3 and [Re(bpy)(CO)3-Ph2PC2H4PPh2-{Re(bpy)(CO)2Ph2PC2H4PPh2-}(n)Re(bpy)(CO)3](PF6)(n+2) (bpy = 2,2'-bipyridine, n = 1, 2) were obtained, showing that they have interligand pi-pi interaction between the bpy ligand and the phenyl groups on the phosphorus ligand. All of the oligomers and polymers synthesized were emissive at room temperature in solution. For the dimers, broad emission was observed with a maximum at 523-545 nm, from the (3)MLCT excited-state of the tricarbonyl complex unit, [Re(N--N)(CO)3-PP-]. Emission from the longer oligomers and polymers with > or = 3 Re(I) units was observed at wavelengths 50-60 nm longer than those of the corresponding dimers. This fact and the emission decay results clearly show that energy transfer from the edge unit to the interior unit occurs with a rate constant of (0.9 x 10(8))-(2.5 x 10(8)) s(-1). The efficient energy transfer and the smaller exclusive volume of the longer Re(I) polymers indicated intermolecular aggregation for these polymers in an MeCN solution.     

Enantiospecific synthesis of delta and lambda [Ru(bpy)(2)ppy](+) and [Ru(bpy)(2)quo](+) (bpy = 2,2'-bipyridine,ppy = phenylpyridine-H(+), quo = 8-hydroxyquinolate): (1)H and (13)C NMR studies and X-ray structure determination of rac-[Ru(bpy)(2)quo]PF(6)

In this paper, we describe the enantiospecific synthesis and the complete characterization of the two hexacoordinated ruthenium(II) monocations [Ru(bpy)(2)ppy](+) and [Ru(bpy)(2)quo](+) (bpy = 2,2'-bipyridine, ppy = phenylpyridine-H(+), quo = 8-hydroxyquinolate) in their enantiomeric Delta and Lambda forms. The corresponding enantiomeric excesses (ee's) are determined by (1)H NMR using pure Delta-Trisphat (tris(tetrachlorobenzenedialato)phosphate(V) anion) as a chiral (1)H NMR shift reagent. A complete (1)H and (13)C NMR study has been carried out on rac-[Ru(bpy)(2)ppy]PF(6) and rac-[Ru(bpy)(2)quo]PF(6). Additionally, the X-ray molecular structure of rac-[Ru(bpy)(2)quo]PF(6) is reported; this latter species crystallizes in the monoclinic C2/c space group (a = 22.079 A, b = 16.874 A, c = 17.533 A, alpha = 90 degrees, beta = 109.08 degrees, gamma = 90 degrees ).     

Homoleptic zinc(II) complexes with first and second coordination shells of 5-tert-butylpyrazole

Reaction of hydrated Zn[NO3]2 or Zn[BF4]2 with four or more equivalents of 3{5}-tert-butylpyrazole (L(tBu)) yields [Zn(L(tBu))4]X2 (X- = NO3- or BF4-). The nitrate complex contains C2-symmetric four-coordinate zinc(II) centers with a slightly flattened tetrahedral geometry, and each nitrate anion hydrogen bonds to two pyrazole N-H groups. Similar reactions with Zn[ClO4]2 or ZnCl2 in the presence of 2 equiv of AgPF6 or AgSbF6 yield instead [{Zn(L(tBu))4}(L(tBu))4][ClO4]2 and [{Zn(L(tBu))4}(L(tBu))2]Y2 (Y- = PF6- or SbF6-). Crystals of [{Zn(L(tBu))4}(L(tBu))4][ClO4]2 are composed of discrete [{Zn(L(tBu))4}(L(tBu))4]2+ supramolecules that are formed from N-H...N hydrogen bonding between zinc-bound and uncoordinated pyrazole rings. The [{Zn(L(tBu))4}(L(tBu))4]2+ moieties are linked into planar 4(4) nets by hydrogen bonding to bridging ClO4- anions. The ClO4- ions are almost perfectly encapsulated in near-spherical cavities of approximate dimensions 5.0 x 5.0 x 4.5 A that are formed by two interlocked supramolecular dications. Similarly, [{Zn(L(tBu))4}(L(tBu))2][PF6]2 crystallizes as discrete supramolecules in the crystal with the PF6- anions occupying a shallow bowl-shaped cavity on the surface of the complex that is formed by two zinc-bound and one uncoordinated pyrazole ligands. (1)H NMR and IR studies of [{Zn(L(tBu))4}(L(tBu))4][ClO4]2 in CD2Cl2 imply that the second-sphere L(tBu) ligands dissociate from the [Zn(L(tBu))4]2+ center in this solvent and that free and metal-bound L(tBu) are in rapid chemical exchange.     

Tuning the redox potentials of dinuclear tungsten oxo complexes [(Cp*W(4,4'-R,R-2,2'-bpy)(mu-O))2][PF6]2 toward photochemical water splitting

A series of novel dinuclear tungsten(IV) oxo complexes with disubstituted 4,4'-R,R-2,2'-bipyridyl (R(2)bpy) ligands of the type [(Cp*W(R(2)bpy)(mu-O))(2)][PF(6)](2) (R=NMe(2), tBu, Me, H, Cl) was prepared by hydrolysis of the tungsten(IV) trichloro complexes [Cp*W(R(2)bpy)Cl(3)]. Cyclic voltammetry measurements for the tungsten(IV) oxo compounds provided evidence for one reversible oxidation and two reversible reductions leading to the oxidation states W(V)W(IV), W(IV)W(III) and W(III)W(III). The corresponding complexes [(Cp*W(R(2)bpy)(mu-O))(2)](n+) [PF(6)](n) (n=0 for R=Me, tBu, and 1, 3 for both R=Me) could be isolated after chemical oxidation/reduction of the tungsten(IV) oxo complexes. The crystal structures of the complexes [(Cp*W(R(2)bpy)(mu-O))(2)][BPh(4)](2) (R=NMe(2), tBu) and [(Cp*W(Me(2)bpy)(mu-O))(2)](n+)[PF(6)](n) (n=0, 1, 2, 3) show a cis geometry with a puckered W(2)O(2) four-membered ring for all compounds except [(Cp*W(Me(2)bpy)(mu-O))(2)] which displays a trans geometry with a planar W(2)O(2) ring. Examining the interaction of these novel tungsten oxo complexes with protons, we were able to show that the W(IV)W(IV) complexes [(Cp*W(R(2)bpy)(mu-O))(2)][PF(6) (-)](2) (R=NMe(2), tBu) undergo reversible protonation, while the W(III)W(III) complexes [(Cp*W(R(2)bpy)(mu-O))(2)] transfer two electrons forming the W(IV)W(IV) complex and molecular hydrogen.     

Ru(bpy)2(L)]Cl2: luminescent metal complexes that bind DNA base mismatches

Here we report the synthesis of luminescent ruthenium complexes that bind DNA base pair mismatches. [Ru(bpy)2(tpqp)]Cl2 (tpqp = 7,8,13,14-tetrahydro-6-phenylquino[8,7-k][1,8]phenanthroline), [Ru(bpy)2(pqp)]Cl2 (pqp = 6-phenylquino[8,7-k][1,8]phenanthroline), and [Ru(bpy)2(tactp)]Cl2 [tactp = 4,5,9,18-tetraazachryseno[9,10-b]triphenylene] have been synthesized, and their spectroscopic properties in the absence and presence of DNA have been examined. While [Ru(bpy)2(pqp)]2+ shows no detectable luminescence, [Ru(bpy)2(tpqp)]2+ is luminescent in the absence and presence of DNA with an excited-state lifetime of 10 ns and a quantum yield of 0.002. Although no increase in emission intensity is associated with binding to mismatch-containing DNA, luminescence quenching experiments and measurements of steady-state fluorescence polarization provide evidence for preferential binding to oligonucleotides containing a CC mismatch. Furthermore, by marking the site of binding through singlet oxygen sensitized damage, the complex has been shown to target a CC mismatch site directly with a specific binding affinity, Kb = 4 x 10(6) M(-1). [Ru(bpy)2(tactp)]2+, an analogue of [Ru(bpy)2(dppz)]2+ containing a bulky intercalating ligand, is luminescent in aqueous solution at micromolar concentrations and exhibits a 12-fold enhancement in luminescence in the presence of DNA. The complex, however, tends to aggregate in aqueous solution; we find a dimerization constant of 9.8 x 10(5) M(-1). Again, by singlet oxygen sensitization it is apparent that [Ru(bpy)2(tactp)]2+ binds preferentially to a CC mismatch; using a DNase I footprinting assay, a binding constant to a CC mismatch of 8 x 10(5) M(-1) is found. Hence results with these novel luminescent complexes support the concept of using a structurally demanding ligand to obtain selectivity in targeting single base mismatches in DNA. The challenge is coupling the differential binding we can obtain to differential luminescence.     

Mixed-transition-metal acetylides: synthesis and characterization of complexes with up to six different transition metals connected by carbon-rich bridging units

The synthesis and reaction chemistry of heteromultimetallic transition-metal complexes by linking diverse metal-complex building blocks with multifunctional carbon-rich alkynyl-, benzene-, and bipyridyl-based bridging units is discussed. In context with this background, the preparation of [1-{(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C}-3-{(tBu(2)bpy)(CO)(3)ReC[triple bond]C}-5-(PPh(2))C(6)H(3)] (10) (dppf = 1,1'-bis(diphenylphosphino)ferrocene; tBu(2)bpy = 4,4'-di-tert-butyl-2,2'-bipyridyl; Ph = phenyl) is described; this complex can react further, leading to the successful synthesis of heterometallic complexes of higher nuclearity. Heterotetrametallic transition-metal compounds were formed when 10 was reacted with [{(eta(5)-C(5)Me(5))RhCl(2)}(2)] (18), [(Et(2)S)(2)PtCl(2)] (20) or [(tht)AuC[triple bond]C-bpy] (24) (Me = methyl; Et = ethyl; tht = tetrahydrothiophene; bpy = 2,2'-bipyridyl-5-yl). Complexes [1-{(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C}-3-{(tBu(2)bpy)(CO)(3)ReC[triple bond]C}-5-{PPh(2)RhCl(2)(eta(5)-C(5)Me(5))}C(6)H(3)] (19), [{1-[(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C]-3-[(tBu(2)bpy)(CO)(3)ReC[triple bond]C]-5-(PPh(2))C(6)H(3)}(2)PtCl(2)] (21), and [1-{(eta(2)-dppf)(eta(5)-C(5)H(5))RuC[triple bond]C}-3-{(tBu(2)bpy)(CO)(3)ReC[triple bond]C}-5-{PPh(2)AuC[triple bond]C-bpy}C(6)H(3)] (25) were thereby obtained in good yield. After a prolonged time in solution, complex 25 undergoes a transmetallation reaction to produce [(tBu(2)bpy)(CO)(3)ReC[triple bond]C-bpy] (26). Moreover, the bipyridyl building block in 25 allowed the synthesis of Fe-Ru-Re-Au-Mo- (28) and Fe-Ru-Re-Au-Cu-Ti-based (30) assemblies on addition of [(nbd)Mo(CO)(4)] (27), (nbd = 1,5-norbornadiene), or [{[Ti](mu-sigma,pi-C[triple bond]CSiMe(3))(2)}Cu(N[triple bond]CMe)][PF(6)] (29) ([Ti] = (eta(5)-C(5)H(4)SiMe(3))(2)Ti) to 25. The identities of 5, 6, 8, 10-12, 14-16, 19, 21, 25, 26, 28, and 30 have been confirmed by elemental analysis and IR, (1)H, (13)C{(1)H}, and (31)P{(1)H} NMR spectroscopy. From selected samples ESI-TOF mass spectra were measured. The solid-state structures of 8, 12, 19 and 26 were additionally solved by single-crystal X-ray structure analysis, confirming the structural assignment made from spectroscopy.     

Scrutinizing low-spin Cr(II) complexes

The oxidation state of the chromium center in the following compounds has been probed using a combination of chromium K-edge X-ray absorption spectroscopy and density functional theory: [Cr(phen)(3)][PF(6)](2) (1), [Cr(phen)(3)][PF(6)](3) (2), [CrCl(2)((t)bpy)(2)] (3), [CrCl(2)(bpy)(2)]Cl(0.38)[PF(6)](0.62) (4), [Cr(TPP)(py)(2)] (5), [Cr((t)BuNC)(6)][PF(6)](2) (6), [CrCl(2)(dmpe)(2)] (7), and [Cr(Cp)(2)] (8), where phen is 1,10-phenanthroline, (t)bpy is 4,4'-di-tert-butyl-2,2'-bipyridine, and TPP(2-) is doubly deprotonated 5,10,15,20-tetraphenylporphyrin. The X-ray crystal structures of complexes 1, [Cr(phen)(3)][OTf](2) (1'), and 3 are reported. The X-ray absorption and computational data reveal that complexes 1-5 all contain a central Cr(III) ion (S(Cr) = (3)/(2)), whereas complexes 6-8 contain a central low-spin (S = 1) Cr(II) ion. Therefore, the electronic structures of 1-8 are best described as [Cr(III)(phen(?))(phen(0))(2)][PF(6)](2), [Cr(III)(phen(0))(3)][PF(6)](3), [Cr(III)Cl(2)((t)bpy(?))((t)bpy(0))], [Cr(III)Cl(2)(bpy(0))(2)]Cl(0.38)[PF(6)](0.62), [Cr(III)(TPP(3?-))(py)(2)], [Cr(II)((t)BuNC)(6)][PF(6)](2), [Cr(II)Cl(2)(dmpe)(2)], and [Cr(II)(Cp)(2)], respectively, where (L(0)) and (L(?))(-) (L = phen, (t)bpy, or bpy) are the diamagnetic neutral and one-electron-reduced radical monoanionic forms of L, and TPP(3?-) is the one-electron-reduced doublet form of diamagnetic TPP(2-). Following our previous results that have shown [Cr((t)bpy)(3)](2+) and [Cr(tpy)(2)](2+) (tpy = 2,2':6',2"-terpyridine) to contain a central Cr(III) ion, the current results further refine the scope of compounds that may be described as low-spin Cr(II) and reveal that this is a very rare oxidation state accessible only with ligands in the strong-field extreme of the spectrochemical series.     

Synthesis, characterization, and crystal structure of alpha-[Ru(azpy)2(NO3)2] (azpy = 2-(phenylazo)pyridine) and the products of its reactions with guanine derivatives

The synthesis and characterization of alpha-[Ru(azpy)2(NO3)2], 1, are reported (azpy is 2-(phenylazo)pyridine; alpha indicates the isomer in which the coordinating pairs ONO2, N(py), and N(azo) are cis, trans, and cis, respectively). The solid-state structure of 1 has been determined by X-ray crystallography. Crystal data: orthorhombic a = 15.423(5) A, b = 14.034(5) A, c = 10.970(5) A, V = 2374(2) A3, space group P2(1)2(1)2(1) (No. 19), Z = 4, Dcalc = 1.655 g cm-3. The structure refinement converged at R1 = 0.042 and wR2 = 0.118 for 3615 unique reflections and 337 parameters. The octahedral complex shows monodentate coordination of the two nitrate ligands. The Ru-N(azo) bond distances (2.014(4) and 1.960(4) A), slightly shorter than the Ru-N(py) bonds (2.031(4) and 2.059(4) A), agree well with the pi-back-bonding ability of the azo groups. The binding of the DNA-model bases 9-ethylguanine (9egua) and guanosine (guo) to 1 has been studied and compared with previously obtained results for the binding of model bases to the bis(bipyridyl)ruthenium(II) complex. The ligands 9egua and guo appear to form monofunctional adducts, which have been isolated as alpha-[Ru(azpy)2(9egua)Cl]PF6, 2, alpha-[Ru(azpy)2(9egua)(H2O)]-(PF6)2, 3, alpha-[Ru(azpy)2(guo)(H2O)](PF6)2, 4, and alpha-[Ru(azpy)2(guo)Cl]Cl, 5. The orientations of 9egua and guo in these complexes have been determined in detail with the use of 2D NOESY NMR spectroscopy. In 2 and 5, H8 is directly pointed toward the coordinated Cl, whereas, in 3 and 4, H8 is wedged between the pyridine and phenyl rings. The guanine derivatives in the azpy complexes can have more orientations than found for related cis-[Ru(bpy)2Cl2] species. This fluxionality is considered to be important in the binding of the alpha-bis(2-(phenylazo)pyridine)ruthenium(II) complex to DNA. In complex 1, ruthenium is the chiral center and in the binding to guanosine, two diastereoisomers each of adducts 4 and 5 have been clearly identified by NMR spectroscopy.     

钌铁双核配合物的合成及猝灭[Ru(bpy)~3]^2^+发光过程研究

合成了含二氮芴和联吡啶等配体的一系列新型钌铁双核配合物:[(C~1~0H~6N~2)C=N-N=CR-Fc)Ru(bpy)~2]·(PF~6)~2,[(C~1~0H~6N~2)C=N--C~6H~4-N=CR-Fc)Ru(bpy)~2]·(PF~6)~2,[(C~1~0H~6N~2)C=N-C~6H~4-C~6H~4-N=CR-Fc)Ru(bpy)~2]·(PF~6)~2,并对其进行了光谱表征,通过对该类配合物的循环伏安和发光光谱研究,讨论其激发态的氧化还原性和对[Ru(bpy)~3]^2^+发光过程的猝灭作用.研究表明猝灭过程为扩散控制的双分子交换能量传递