Total enantioselectivity in the DNA binding of the dinuclear ruthenium(II) complex [[Ru(Me2bpy)2]2(mu-bpm)]4+ [bpm = 2,2'-bipyrimidine; Me2bpy = 4,4'-dimethyl-2,2'-bipyridine

The binding of the three stereoisomers (DeltaDelta-, LambdaLambda- and DeltaLambda-) of the dinuclear ruthenium(II) complex [[Ru(Me2bpy)2]2(mu-bpm)]4+ [Me2bpy = 4,4'-dimethyl-2,2'-bipyridine; bpm = 2,2'-bipyrimidine] to a tridecanucleotide containing a single adenine bulge has been studied by 1H NMR spectroscopy. The addition of the DeltaDelta-isomer to d(CCGAGAATTCCGG)2 induced significant chemical shift changes for the base and sugar resonances of the residues at the bulge site (G3A4G5/C11C10), whereas small shifts were observed upon addition of the enantiomeric LambdaLambda-form. NOESY spectra of the tridecanucleotide bound with the DeltaDelta-isomer revealed intermolecular NOE's between the metal complex and the nucleotide residues at the bulge site, while only weak NOE's were observed to terminal residues to the LambdaLambda-form. Competitive binding studies were performed where both enantiomers were simultaneously added to the tridecanucleotide, and for all ratios of the two stereoisomers the DeltaDelta-isomer remained selectively bound at the bulge site with the LambdaLambda-enantiomer localised at the terminal regions of the tridecanucleotide. The meso-diastereoisomer (DeltaLambda) was found to bind to the tridecanucleotide with characteristics intermediate between the DeltaDelta- and LambdaLambda-enantiomers of the rac form. Two distinct sets of metal complex resonances were observed, with one set having essentially the same shift as the free metal complex, whilst the other set of resonances exhibited significant shifts. The NOE data indicated that the meso-diastereoisomer does not bind as selectively as the DeltaDelta-isomer, with NOE's observed to a greater number of nucleotide residues compared to the DeltaDelta-form. This study provides a rare example of total enantioselectivity in the binding of an inert transition metal complex to DNA, produced by the shape recognition of both ruthenium(II) centres.     

Dinuclear ruthenium(ii) complexes with flexible bridges as non-duplex DNA binding agents

The stereoisomers of a series of dinuclear ruthenium(ii) complexes [{Ru(phen)(2)}(2)(micro-BL)](4+) (phen = 1,10-phenanthroline) with flexible bridging ligands (BL) bb2 {1,2-bis[4(4'-methyl-2,2'-bipyridyl)]ethane}, bb5 {1,5-bis[4(4'-methyl-2,2'-bipyridyl)]pentane}, bb7 {1,7-bis[4(4'-methyl-2,2'-bipyridyl)]heptane}, and bb10 {1,10-bis[4(4'-methyl-2,2'-bipyridyl)]decane} have been synthesised. Their binding to a control dodecanucleotide, d(CCGGAATTCCGG)(2), and a tridecanucleotide, d(CCGAGAATTCCGG)(2), which contains a single adenine bulge have been studied using fluorescence displacement assays involving intercalating and groove-binding dyes, equilibrium dialysis and binding affinity chromatography. The fluorescence intercalator displacement (FID) assay indicated that LambdaLambda-[{Ru(phen)(2)}(2)(micro-bb7)](4+) had the greatest binding affinity with all the oligonucleotides, whereas an analogous fluorescence technique using a minor-groove binding dye, equilibrium dialysis and affinity binding chromatography showed that DeltaDelta-[{Ru(phen)(2)}(2)(micro-bb7)](4+) had the strongest binding. An (1)H NMR study of the binding of the DeltaDelta-enantiomer of [{Ru(phen)(2)}(2)(micro-bb7)](4+) to d(CCGAGAATTCCGG)(2) confirmed the selectivity of the metal complex for the bulge site and provided the basis for an energy-minimised binding model of the dinuclear ruthenium complex with the single adenine bulge containing trinucleotide. The binding model demonstrated the ability of the flexibly-linked complex to follow the curvature of the DNA minor groove.     

Interplay of cubic building blocks in (et6-arene)ruthenium-containing tungsten and molybdenum oxides

A series of molybdenum and tungsten organometallic oxides containing [Ru(arene)]2+ units (arene =p-cymene, C6Me6) was obtained by condensation of [[Ru(arene)Cl2]2] with oxomolybdates and oxotungstates in aqueous or nonaqueous solvents. The crystal structures of [[Ru(eta6-C6Me6]]4W4O16], [[Ru(eta6-p-MeC6H4iPr]]4W2O10], [[[Ru-(eta6-p-MeC6H4iPr)]2(mu-OH)3]2][[Ru(eta6-p-MeC6H4iPr)]2W8O28(OH)2[Ru(eta6-p-MeC6H4iPr)(H2O)]2], and [[Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) have been determined. While the windmill-type clusters [[Ru(eta6-arene)]4(MO3)4(mu3-O)4] (M = Mo, W; arene =p-MeC6H4iPr, C6Me6), the face-sharing double cubane-type cluster [[Ru(eta6-p-MeC6H4iPr)]4(WO2)2(mu3-O)4(mu4-O)2], and the dimeric cluster [[Ru(eta6-p-MeC6H4iPr)(WO3)3(mu3-O)3(mu3-OH)Ru(eta6-pMeC6H4iPr)(H2O)]2(mu-WO2)2]2- are based on cubane-like units, [(Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) are more properly described as lacunary Lindqvist-type polyoxoanions supporting three ruthenium centers. Precubane clusters [[Ru(eta6-arene)](MO3)2(mu-O)3(mu3-O)]6- are possible intermediates in the formation of these clusters. The cluster structures are retained in solution, except for [[Ru(eta6-p-MeC6H4iPr)]4Mo4O16], which isomerizes to the triple-cubane form.     

Inert benzothiazole functionalised ruthenium(II) complexes; potential DNA hairpin binding agents

The two enantiomers of [Ru(bpy)2(bbtb)]2+{bpy = 2,2'-bipyridine; bbtb = 4,4'-bis(benzothiazol-2-yl)-2,2'-bipyridine} have been isolated and fully characterised. Both enantiomers have been shown to have a strong association with calf thymus DNA by UV/visible absorption, emission and CD spectroscopy, with the Lambda enantiomer having the greater affinity. The binding of both enantiomeric forms of [Ru(bpy)2(Me2bpy)]2+ and [Ru(bpy)2(bbtb)]2+{Me(2)bpy = 4,4'-dimethyl-2,2'-bipyridine} to a range of oligonucleotides, including an octadecanucleotide and an icosanucleotide which contain hairpin-sequences, have been studied using a fluorescent intercalator displacement (FID) assay. The complex [Ru(bpy)2(bbtb)]2+ exhibited an interesting association with hairpin oligonucleotides, again with the Lambda enantiomer binding more strongly. A (1)H NMR spectroscopic study of the binding of both enantiomers of [Ru(bpy)2(bbtb)]2+ to the icosanucleotide d(CACTGGTCTCTCTACCAGTG) was conducted. This sequence contains a seven-base-pair duplex stem and a six-base hairpin-loop. The investigation gave an indication of the relative binding of the complexes between the two different regions (duplex and secondary structure) of the oligonucleotide. The results suggest that both enantiomers bind at the hairpin, with the ruthenium centre located at the stem-loop interface. NOE studies indicate that one of the two benzothiazole substituents of the bbtb ligand projects into the loop-region. A simple model of the metal complex/oligonucleotide adduct was obtained by means of molecular modelling simulations. The results from this study suggest that benzothiazole complexes derived from inert polypyridine ruthenium(II) complexes could lead to the development of new fluorescent DNA hairpin binding agents.     

吲哚咪唑基钌(Ⅱ)联吡啶配合物与酵母RNA的相互作用

通过紫外-可见光谱和荧光光谱滴定、稳态荧光猝灭和溴化乙啶竞争键合实验研究了Ru(Ⅱ)配合物[Ru(bpy)(H₂iip)₂](ClO₄)₂{bpy=2,2′-联吡啶, H₂iip=2-(吲哚-3-基)-咪唑[4,5-f][1,10]-邻菲罗啉}的酵母RNA键合性质. 结果表明, 二者键合模式为嵌入键合, 其键合常数为7.09×10⁶ L/mol, 比小牛胸腺DNA的键合常数大, 且比同类配合物[Ru(bpy)₂(H₂iip)](ClO₄)₂的酵母RNA键合常数大.     

Multisite effects on intervalence charge transfer in a clusterlike trinuclear assembly containing ruthenium and osmium

The intervalence charge transfer (IVCT) properties of the mixed-valence forms of the diastereoisomers of the dinuclear [[Ru(bpy)2](mu-HAT)[M(bpy)2]]5+ (M = Ru or Os) complexes and the trinuclear heterochiral [[Ru(bpy)2]2[Os(bpy)2](mu-HAT)]n+ (n = 7, 8; HAT = 1,4,5,8,9,12-hexaazatriphenylene; bpy = 2,2'-bipyridine) species display a marked dependence on the nuclearity and extent of oxidation of the assemblies, while small differences are also observed for the diastereoisomers of the same complex in the dinuclear cases. The mixed-valence heterochiral [[Ru(bpy)2]2[Os(bpy)2](mu-HAT)]n+ (n = 7, 8) forms exhibit IVCT properties that are intermediate between those of the diastereoisomeric forms of the localized hetero-dinuclear complex [[Ru(bpy)2](mu-HAT)[Os(bpy)2]]5+ and the borderline localized-to-delocalized homo-trinuclear complex [[Ru(bpy)2]3(mu-HAT)]n+ (n = 7, 8). The near-infrared (NIR) spectrum of the +7 mixed-valence species exhibits both interconfigurational (IC) and IVCT transitions which are quantitatively similar to those in [[Ru(bpy)2](mu-HAT)[Os(bpy)2]]5+ and are indicative of the localized mixed-valence formulation [[Ru(II)(bpy)2]2[Os(III)(bpy)2](mu-HAT)]7+. The +8 state exhibits a new band attributable to an IVCT transition in the near-infrared region.     

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.     

Proton-driven self-assembled systems based on cyclam-cored dendrimers and [Ru(bpy)(CN)4]2-

1,4,8,11-tetraazacyclotetradecane (cyclam), which is one of the most extensively investigated ligands in coordination chemistry, in its protonated forms, can play the role of host toward cyanide metal complexes. We have investigated the acid-driven adducts formed in acetonitrile-dichloromethane (1:1 v/v) solution by [Ru(bpy)(CN)4](2-) with 1,4,8,11-tetrakis(naphthylmethyl)cyclam (1) and a dendrimer consisting of a cyclam core appended with 12 dimethoxybenzene and 16 naphthyl units (2). [Ru(bpy)(CN)4](2-), 1, and 2 exhibit characteristic absorption and emission bands, in distinct spectral regions, that are strongly affected by addition of acid. When a solution containing equimolar amounts of [Ru(bpy)(CN)4](2-) and 1 or 2 is titrated by trifluoroacetic acid, or when [Ru(bpy)(CN)4](2-) is titrated with (1.2H)2+ or (2.2H)2+, [[Ru(bpy)(CN)4](2-).(2H+).1] or [[Ru(bpy)(CN)4](2-).(2H+).2] adducts are formed in which the fluorescence of the naphthyl units is strongly quenched by very efficient energy transfer to the metal complex, as shown by the sensitized luminescence of the latter. The [[Ru(bpy)(CN)4]2-.(2H+).1] and [[Ru(bpy)(CN)4](2-).(2H+).2] adducts can be disrupted (i) by addition of a base (1,4-diazabicyclo[2.2.2]octane), yielding the starting species [Ru(bpy)(CN)4](2-) and 1 or 2, or (ii) by further addition of triflic acid, with formation of (1.2H)2+ or (2.2H)2+ and protonated forms of [Ru(bpy)(CN)4](2-). It is shown that upon stimulation with two chemical inputs (acid and base) both [[Ru(bpy)(CN)4](2-).(2H+).1] and [[Ru(bpy)(CN)4](2-).(2H+).2] exhibit two distinct optical outputs (a naphthalene-based and a Ru(bpy)-based emission) that behave according to an XOR and an XNOR logic, respectively.     

Ruthenium complexes with the stanna-closo-dodecaborate ligand: coexistence of eta1(Sn) and eta3(B-H) coordination

Four stanna-closo-dodecaborate complexes of ruthenium have been prepared and characterized by multinuclear NMR studies in solution and in the solid state. The solid-state structures of the dimeric zwitterions [[Ru(dppb)(SnB11H11)]2] (2) (dppb = bis(diphenylphosphino)butane), [[Ru(PPh3)2(SnB11H11)]2] (3), and the dianionic ruthenium complex [Bu3MeN]2[Ru(dppb)[2,7,8-(mu-H)3-exo-SnB11H11](SnB11H11)] (4) were determined by X-ray crystal structure analysis; they establish an unprecedented structural motif in the chemistry of heteroboranes and transition-metal fragments with the stanna-closo-dodecaborate moiety as a two-faced ligand that exhibits eta1(Sn) as well as eta3(B-H) coordination. The eta3-coordinated stannaborate in 4 and in the isostructural compound [Bu3MeN]2[Ru(PPh3)2[2,7,8-(mu-H)3-exo-SnB11H11](SnB11H11)] (5) shows fluxional behavior, which was studied in detail by using 31P[1H] EXSY and DNMR experiments. The activation parameters for the dynamic process of 5 are given.     

Synthesis of mononuclear and dinuclear ruthenium(II) tris(heteroleptic) complexes via photosubstitution in bis(carbonyl) precursors

A novel, and quite general, approach for the preparation of tris(heteroleptic) ruthenium(II) complexes is reported. Using this method, which is based on photosubstitution of carbonyl ligands in precursors such as [Ru(bpy)(CO)(2)Cl(2)] and [Ru(bpy)(Me(2)bpy)(CO)(2)](PF(6))(2), mononuclear and dinuclear Ru(II) tris(heteroleptic) polypyridyl complexes containing the bridging ligands 3,5-bis(pyridin-2-yl)-1,2,4-triazole (Hbpt) and 3,5-bis(pyrazin-2-yl)-1,2,4-triazole (Hbpzt) have been prepared. The complexes obtained were purified by column chromatography and characterized by HPLC, mass spectrometry, 1H NMR, absorption and emission spectroscopy and by electrochemical methods. The X-ray structures of the compounds [Ru(bpy)(Me(2)bpy)(bpt)](PF(6))x0.5C(4)H(10)O [1x0.5C(4)H(10)O], [Ru(bpy)(Me(2)bpy)(bpzt)](PF(6))xH(2)O (2xH(2)O) and [Ru(bpy)(Me(2)bpy)(CH(3)CN)(2)](PF(6))(2)xC(4)H(10)O (6xC(4)H(10)O) are reported. The synthesis and characterisation of the dinuclear analogues of 1 and 2, [{Ru(bpy)(Me(2)bpy)}(2)bpt](PF(6))(3)x2H(2)O (3) and [{Ru(bpy)(Me(2)bpy)}(2)bpzt](PF(6))(3) (4), are also described.     

Structural, redox, and photophysical studies of the tetra(pyridyl)porphyrin complex containing four (2,2'-bipyridine)(2,2':6',2"-terpyridine)ruthenium(II) groups

New hybrid complexes of polypyridyl ruthenium and pyridylporphyrins have been prepared by the coordination of pyridyl nitrogens to the ruthenium centers. A 1:4 hybrid complex, [{Ru(bpy)(trpy)}4(mu4-H2Py4P)]8+ ([1]8+) (bpy = 2,2'-bipyridine; trpy = 2,2':6',2"-terpyridine; H2Py4P = 5,10,15,20-tetra(4-pyridyl)porphyrin), has been characterized by the single-crystal X-ray diffraction method. A 1:1 complex, [{Ru(bpy)(trpy)}(H2PyT3P)]2+ ([2]2+) (H2PyT3P = 5-(4-pyridyl)tritolylporphyrin) has also been prepared. The Soret band of the porphyrin ring shifts to longer wavelength with some broadening, the extent of the shift being larger for [1]8+. Cyclic voltammograms of the two complexes show simple overlap of the component redox waves. The complexes are weakly emissive at room temperature, which becomes stronger at lower temperatures. While [1]8+ at >140 K and [2]2+ at 77-280 K show only porphyrin fluorescence, [1]8+ at <140 K shows ruthenium and porphyrin phosphorescence, in addition to the porphyrin fluorescence.     

meso-[{Ru(phen)2}2(mu-HAT)]4+: a high-affinity DNA hairpin probe {HAT = 1,4,5,8,9,12-hexaazatriphenylene; phen = 1,10-phenanthroline}

1H NMR spectroscopy and fluorescent intercalator displacement (FID) assays have been used to investigate the DNA-binding abilities of two series of dinuclear polypyridyl ruthenium(II) complexes of the form [{Ru(L)2}2(mu-BL)]4+ {L = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), 1,10-phenanthroline (phen), or 4,7-dimethyl-1,10-phenanthroline (Me2phen); BL = 2,2'-bipyrimidine (bpm) or 1,4,5,8,9,12-hexaazatriphenylene (HAT)}. Preliminary FID surveys of these metal complexes against a variety of different oligonucleotides revealed that those complexes based upon the HAT bridging ligand induced greater fluorescence decreases in dye-bound DNA than did their bpm-bridged counterparts, suggesting a higher binding affinity by the HAT-bridged species. Furthermore, the greatest fluorescence decreases were typically observed in an oligonucleotide featuring a six-base hairpin loop. The apparent binding affinity of the metal complexes was also found to be a function of the stereochemistry and identity of the terminal ligands of the complex. The meso (DeltaLambda) stereoisomer generally induced greater fluorescence decreases than did either enantiomer (DeltaDelta or LambdaLambda), phen-based terminal ligands performed better than bpy-based terminal ligands, and those terminal ligands with methyl substituents demonstrated stronger apparent binding than did their non-methylated analogues. NMR experiments on meso-[{Ru(phen)2}2(mu-HAT)]4+ and meso-[{Ru(Me2phen)2}2(mu-HAT)]4+ demonstrated that both complexes bound with high affinity to the six-base hairpin oligonucleotide at the stem-loop interface and provided evidence to support stronger binding by the methylated species. meso-[{Ru(phen)2}2(mu-HAT)]4+ was found to bind poorly to duplex DNA and smaller four-base hairpin loops in FID and NMR experiments, whereas FID data suggest that the methylated analogue binds relatively strongly to most oligonucleotide sequences (the four- and six-base hairpins in particular). These results demonstrate that binding affinity can come at the expense of selectivity, with meso-[{Ru(phen)2}2(mu-HAT)]4+ proving to be an efficient compromise between the two as a high-affinity DNA hairpin probe.     

Enhancement of metal-metal coupling at a considerable distance by using 4-pyridinealdazine as a bridging ligand in polynuclear complexes of rhenium and ruthenium

Novel polynuclear complexes of rhenium and ruthenium containing PCA (PCA = 4-pyridinecarboxaldehyde azine or 4-pyridinealdazine or 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) as a bridging ligand have been synthesized as PF(6-) salts and characterized by spectroscopic, electrochemical, and photophysical techniques. The precursor mononuclear complex, of formula [Re(Me(2)bpy)(CO)(3)(PCA)](+) (Me(2)bpy = 4,4'-dimethyl-2,2'-bipyridine), does not emit at room temperature in CH(3)CN, and the transient spectrum found by flash photolysis at lambda(exc) = 355 nm can be assigned to a MLCT (metal-to-ligand charge transfer) excited state [(Me(2)bpy)(CO)(3)Re(II)(PCA(-))](+), with lambda(max) = 460 nm and tau < 10 ns. The spectral properties of the related complexes [[Re(Me(2)bpy)(CO)(3)}(2)(PCA)](2+), [Re(CO)(3)(PCA)(2)Cl], and [Re(CO)(3)Cl](3)(PCA)(4) confirm the existence of this low-energy MLCT state. The dinuclear complex, of formula [(Me(2)bpy)(CO)(3)Re(I)(PCA)Ru(II)(NH(3))(5)](3+), presents an intense absorption in the visible spectrum that can be assigned to a MLCT d(pi)(Ru) --> pi(PCA); in CH(3)CN, the value of lambda (max) = 560 nm is intermediate between those determined for [Ru(NH(3))(5)(PCA)](2+) (lambda(max) = 536 nm) and [(NH(3))(5)Ru(PCA)Ru(NH(3))(5)](4+) (lambda(max) = 574 nm), indicating a significant decrease in the energy of the pi-orbital of PCA. The mixed-valent species, of formula [(Me(2)bpy)(CO)(3)Re(I)(PCA)Ru(III)(NH(3))(5)](4+), was obtained in CH(3)CN solution, by bromine oxidation or by controlled-potential electrolysis at 0.8 V in a OTTLE cell of the [Re(I),Ru(II)] precursor; the band at lambda(max) = 560 nm disappears completely, and a new band appears at lambda(max) = 483 nm, assignable to a MMCT band (metal-to-metal charge transfer) Re(I) --> Ru(III). By using the Marcus-Hush formalism, both the electronic coupling (H(AB)) and the reorganization energy (lambda) for the metal-to-metal intramolecular electron transfer have been calculated. Despite the considerable distance between both metal centers (approximately 15.0 Angstroms), there is a moderate coupling that, together with the comproportionation constant of the mixed-valent species [(NH(3))(5)Ru(PCA)Ru(NH(3))(5)](5+) (K(c) approximately 10(2), in CH(3)CN), puts into evidence an unusual enhancement of the metal-metal coupling in the bridged PCA complexes. This effect can be accounted for by the large extent of "metal-ligand interface", as shown by DFT calculations on free PCA. Moreover, lambda is lower than the driving force -DeltaG degrees for the recombination charge reaction [Re(II),Ru(II)] --> [Re(I),Ru(III)] that follows light excitation of the mixed-valent species. It is then predicted that this reverse reaction falls in the Marcus inverted region, making the heterodinuclear [Re(I),Ru(III)] complex a promising model for controlling the efficiency of charge-separation processes.     

[Ru(bpy)_2tpphz]~(2+)与Zn~(2+)形成的双核配合物的荧光性质研究

近年来,钌多吡啶配合物与DNA的作用得到了比较广泛的研究,并且发展了一系列具有特定功能的钌配合物犤1犦。如传统的DNA分子光开关犤Ru(bpy)2dppz犦2+和犤Ru(phen)2dppz犦2+犤2,3犦(bpy=2,2'-联吡啶,phen=1,10-菲咯啉,dppz=二吡啶犤3,2-a:2',3'-c犦吩嗪)。这些配合物与DNA具有较强的结合力,在水溶液中几乎不发光,但在DNA存在下则有强烈荧光发出。这是由于配合物插入DNA的碱基对之后,保护了dppz的吡嗪环上的N原子,使其免受水分子的进攻从而导致配合物荧光的恢复。但是对于大多数的多吡啶钌配合物来讲,由于其自身较强的背景荧光或与DN…     

Electrophilic ruthenium(VI) nitrido complex containing Kläui's oxygen tripodal ligand

Treatment of [n-Bu4N][Ru(N)Cl4] with [AgL(OEt)] (L(OEt)- = [(eta5-C5H5)Co{P(O)(OEt)2}3]-) afforded the ruthenium(VI) nitrido complex [L(OEt)Ru(N)Cl2] (1), which reacted with PPh3 to give the ruthenium(IV) phosphiniminato complex [L(OEt)Ru(NPPh3)Cl2] (2). The cyclic voltammogram of 2 displays the RuIV/III couple at ca. 0 V vs ferrocenium/ferrocene. Treatment of 1 with Me3NO afforded [LOEtRu(NO)Cl2] (3), which reacted with Ag(OTf) (OTf- = triflate) to give the chloro-bridged tetranuclear ruthenium/silver complex [L(OEt)Ru(NO)Cl2]2[Ag(OTf)]2 (4). Treatment of 1 with Na2S2O3 gave the thionitrosyl complex [L(OEt)Ru(NS)Cl2] (5). The solid-state structures of 1-4 have been established by X-ray crystallography.     

Ammonolysis of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives

Ammonolyses of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives [Ti(eta5-C5Me5)X3] (X = NMe2, Me, Cl) have been carried out in solution to give polynuclear nitrido complexes. Reaction of the tris(dimethylamido) derivative [Ti(eta5-C5Me5)(NMe2)3] with excess of ammonia at 80-100 degrees C gives the cubane complex [[Ti(eta5-C5Me5)]4(mu3-N)4] (1). Treatment of the trimethyl derivative [Ti(eta5-C5Me5)Me3] with NH3 at room temperature leads to the trinuclear imido-nitrido complex [[Ti(eta/5-CsMes)(mu-NH)]3(mu3-N)] (2) via the intermediate [[Ti(eta5-C5Me5)Me]2(mu-NH)2] (3). The analogous reaction of [Ti(eta5-C5Me5)Me3] with 2,4,6-trimethylaniline (ArNH2) gives the dinuclear imido complex [[Ti(eta5-C5Me5)Me])2(mu-NAr)2] (4) which reacts with ammonia to afford [[Ti(eta5-C5Me5)(NH2)]2(mu-NAr)2] (5). Complex 2 has been used, by treatments with the tris(dimethylamido) derivatives [Ti(eta5-C5H5-nRn)(NMe2)3], as precursor of the cubane nitrido systems [[Ti4(eta5-C5Me5)3(eta5-C5H5-nRn)](mu3-N)4] [R = Me n = 5 (1), R = H n = 0 (6), R = SiMe3 n = 1 (7), R = Me n = 1 (8)] via dimethylamine elimination. Reaction of [Ti(eta5-C5Me5)Cl3] or [Ti(eta5-C5Me5)(NMe2)Cl2] with excess of ammonia at room temperature gives the dinuclear complex [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) where an intramolecular hydrogen bonding and a nonlineal nitrido ligand bridge the "Ti(eta5-C5Me5)Cl(NH3)" and "Ti(eta5-C5Me5)Cl2" moieties. The molecular structures of [[Ti(eta5-C5Me5)Me]2 (mu-NAr)2] (4) and [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) have been determined by X-ray crystallographic studies. Density functional theory calculations also have been conducted on complex 9 to confirm the existence of an intramolecular N-H...Cl hydrogen bond and to evaluate different aspects of its molecular disposition.     

手性钌配合物的合成、抗肿瘤活性及其与血清蛋白的相互作用

合成了手性钌配合物Δ, Λ-[Ru(bpy)₂(pyip)]²⁺, 通过元素分析、核磁共振、质谱和CD光谱对配合物进行了表征. 采用MTT法评价了3种异构体对多种肿瘤细胞株的体外抗肿瘤活性以及对正常细胞的毒性. 结果表明, Δ-[Ru(bpy)₂(pyip)]²⁺的抗肿瘤活性明显优于其异构体, 对A375, SW480, MCF-7和A549的半数抑制浓度低于顺铂. 通过荧光光谱法研究了在生理pH条件下, 手性钌配合物与牛血清白蛋白(BSA)之间的结合作用以及荧光猝灭机制. 依据Scatchard方程测定了结合常数和结合位点数, 根据热力学方程讨论了两者间的主要作用力类型. 结果表明, 钌配合物对牛血清白蛋白的荧光猝灭机制为静态猝灭. Δ-1, 1和Λ-1与牛血清白蛋白的结合常数分别为1.16×10⁵, 5.12×10⁴和3.64×10⁴, 结合位点数均为1, 主要作用力类型是静电作用. 钌配合物在体内能够被血清蛋白存储转运且结合时对蛋白构象无影响.     

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.     

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.     

Ruthenium complexes of substituted hydrazine: new solution- and solid-state binding modes

The methylhydrazine complex [Ru(NH(2)NHMe)(PyP)(2)]Cl(BPh(4)) (PyP=1-[2-(diphenylphosphino)ethyl]pyrazole) was synthesised by addition of methylhydrazine to the bimetallic complex [Ru(mu-Cl)(PyP)(2)](2)(BPh(4))(2). The methylhydrazine ligand of the ruthenium complex has two different binding modes: side-on (eta(2)-) when the complex is in the solid state and end-on (eta(1)-) when the complex is in solution. The solid-state structure of [Ru(PyP)(2)(NH(2)NHMe)]Cl(BPh(4)) was determined by X-ray crystallography. 2D NMR spectroscopic experiments with (15)N at natural abundance confirmed that in solution the methylhydrazine is bound to the metal centre by only the -NH(2) group and the ruthenium complex retains an octahedral conformation. Hydrazine complexes [RuCl(PyP)(2)(eta(1)-NH(2)NRR')]OSO(2)CF(3) (in which R=H, R'=Ph, R=R'=Me and NRR'=NC(5)H(10)) were formed in situ by the addition of phenylhydrazine, 1,1-dimethylhydrazine and N-aminopiperidine, respectively, to a solution of the bimetallic complex [Ru(mu-Cl)(PyP)(2)](2)(OSO(2)CF(3))(2) in dichloromethane. These substituted hydrazine complexes of ruthenium were shown to exist in an equilibrium mixture with the bimetallic starting material.