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1.
The first crystal structure of NiII phen-dione complex is reported. This compound is [Ni(bpy)2(phen-dione)](PF6)2 (bpy = 2,2′-bipyridine and phen-dione = 1,10-phenanthroline-5,6-dione). The complex has been characterized by elemental analysis, IR and electronic absorption spectroscopy and cyclic voltammetry. The electrochemical behavior and electronic spectrum of [Ni(bpy)2(phen-dione)](OAc)2 has also been studied in buffered solutions at pH between 1 and 8. ORTEP drawing of [Ni(bpy)2(phen-dione)](PF6)2 · 2CH3CN shows that the coordination geometry around the NiII is a distorted octahedron, with bite angles of 78.1-78.8° for all three bidentate ligands and the two pyridyl rings of the bpy ligands are nearly co-planar, as are the two pyridyl rings of phen-dione.  相似文献   

2.
A comparative study of metallophilic interactions of [Pt(tpy)X]+ cations (tpy = 2,2′:6′,2″-terpyridine) in the presence of two different types of anions, (i) [] anions that form double salts and (ii) simple p-block anions, is reported. Single-crystal X-ray diffraction data, solution-state 195Pt NMR spectra, and variable temperature solid-state luminescence spectra are reported. Three [Pt(tpy)Cl]Y derivatives (Y = SbF6, 1, SbF6·CH3CN, 4, PF6, 2) and the [Pt(tpy)Br]PF6 analog, 3, as well as two new double salts [Pt(tpy)CN][Au(CN)2], 5, and [Pt(tpy)CN]2[Au(C6F5)2](PF6), 6, have been synthesized and characterized. Structural analysis shows consistent patterns in Pt···Pt interactions that vary slightly depending on the coordinating halogen or pseudo-halogen X, counter anion Y, and lattice solvent. Metallophilic interactions are seen between [Pt(tpy)X]+ cations with all types of X ligands, but only with π-accepting X′ ligands from [] anions are Pt?Au metallophilic interactions seen to be favored over Pt?Pt interactions. The [Au(CN)2] anion consistently forms Pt···Au metallophilic contacts, unlike [Au(C6F5)2]. The 195Pt NMR chemical shifts are ∼−2750 ppm for π-donor ligands and near −3120 ppm for π-acceptor ligands in [Pt(tpy)X]PF6 compounds. Luminescence data show an unusual blue shift in [Pt(tpy)CCPh][Au(C6F5)2] versus [Pt(tpy)CCPh]PF6 ascribed to an intermolecular charge transfer.  相似文献   

3.
The heteroleptic complexes, [(MePhtpy)RuCl(dpp)](PF6) and [(tpy)RuCl(dpp)](PF6), have been synthesized, characterized, and investigated with respect to their photophysical, redox, and DNA photocleavage properties (where MePhtpy = 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine and dpp = 2,3-bis(2-pyridyl)pyrazine, tpy = 2,2′:6′,2′′-terpyridine). The X-ray crystal structure confirms the identity of the new [(MePhtpy)RuCl(dpp)](PF6) complex. These heteroleptic complexes were found to photocleave DNA in the presence of oxygen, unlike the previously studied complex, [Ru(tpy)2](PF6)2. The photophysical, redox, and DNA photocleavage properties of the heteroleptic complexes were compared with those of the homoleptic complexes, [Ru(MePhtpy)2](PF6)2 and [Ru(tpy)2](PF6)2. The heteroleptic complexes showed intense metal to ligand charge transfer (MLCT) transition at lower energy ([(MePhtpy)RuCl(dpp)](PF6), 522 nm; [(tpy)RuCl(dpp)](PF6), 516 nm) and longer excited state lifetimes as compared to the homoleptic complexes. The [Ru(MePhtpy)2]2+ complex was found to photocleave DNA in contrast to [Ru(tpy)2]2+. The introduction of a methylphenyl group on the tepyridine ligand not only enhances the 3MLCT excited state lifetime but also increases the lipophilicity and thereby the DNA binding ability of the molecule. An increase in lipophilicity upon addition of a methylphenyl group on the 2,2′:6′,2′′-terpyridine ligand was confirmed by determination of the partition coefficient ([(MePhtpy)RuCl(dpp)](PF6), log P = +1.16; [(tpy)RuCl(dpp)](PF6), log P = −1.27). The heteroleptic complexes photocleave DNA more efficiently than the homoleptic complexes, with the greatest activity being observed for the newly prepared [(MePhtpy)RuCl(dpp)](PF6) complex.  相似文献   

4.
Ruthenium phosphine complexes with a CO ligand [Ru(tpy)(PR3)(CO)Cl]+ (tpy = 2,2′:6′,2″-terpyridine, R = Ph or p-tolyl), were prepared by introduction of CO gas to the corresponding dichloro complexes at room temperature. New carbonyl complexes were characterized by various methods including structural analyses. They were shown to release CO following the addition of several N-donors to form the corresponding substituted complexes. The kinetic data and structural results observed in this study indicated that the CO release reactions proceeded in an interchange mechanism. The molecular structures of [Ru(tpy)(PPh3)(CO)Cl]PF6, [Ru(tpy)(P(p-tolyl)3)(CO)Cl]PF6 and [Ru(tpy)(PPh3)(CH3CN)Cl]PF6 were determined by X-ray crystallography.  相似文献   

5.
The ruthenium complexes, trans-[Ru(phen-NH-phen)(eina)2](PF6)2 and trans-[Ru(phen-NH-phen)(ina)2](PF6)2 where phen-NH-phen = N,N-bis(1,10-phenanthroline-2-yl)amine, ina = isonicotinic acid and eina = ethyl isonicotinate, have been synthesized and characterized by 1H NMR, elemental analysis, and IR spectroscopy. The compounds were non-emissive at room temperature, but displayed intense photoluminescence in 4:1 ethanol/methanol glasses at 77 K with corrected emission maximum at 570-580 nm. A quasi-reversible wave observed in cyclic voltammetry experiments was assigned to the RuIII/II couple, (trans-[Ru(phen-NH-phen)(eina)2)3+/2+ = +1.22 V versus Ag/AgCl. The trans-[Ru(phen-NH-phen)(ina)2](PF6)2 compound was found to bind to nanocrystalline TiO2 thin films from acetonitrile solution. Pulsed 532 nm excitation of trans-[Ru(phen-NH-phen)(ina)2](PF6)2 anchored to mesoporous nanocrystalline TiO2 thin films resulted in an absorption difference spectra consistent with the formation of an interfacial charge separated state trans-[RuIII (phen-NH-phen)(ina)2]+/TiO2 (e). The formation of this state could not be time resolved, consistent with rapid excited state injection into the TiO2, kinj > 108 s−1. Comparative measurements with a thin film actinometer yielded an injection quantum yield (?inj) of 0.8. Charge recombination required milliseconds for completion and followed a bi-second-order equal concentration kinetic model with k1 = 1.0 × 108 s−1, and k2 = 3.0 × 105 s−1. In regenerative solar cells with 0.5 M LiI and 0.005 M I2 in acetonitrile, incident photon-to-current efficiencies were typically less than 10%.  相似文献   

6.
Preliminary pharmacological studies of various nitric oxide (NO) photo-releasing agents are reported based on the flash-photolysis studies of the nitro ruthenium complexes cis-[RuII(NO2)L(bpy)2]+ (bpy = 2,2′-bipyridine and L = pyridine, 4-picoline and pyrazine) and [RuII(NO2)(bpy)(terpy)]+ (terpy = terpyridine) in physiological medium. The net photoreactions under these conditions are two primary photoproducts, in (I) there is RuII-NO2 photoaquation, where the photoproducts are RuII-H2O plus and (II) homolytic dissociation of NO from a coordinated nitrito to derive the RuII-OH2 specie and NO. Based on photochemical processes, the nitro ruthenium complexes were incorporated in water in oil (W/O) microemulsion and used in the vasorelaxation induced experiment. Denuded rat aortas were contracted with KCl and nitro ruthenium complexes in microemulsion were added. Perfusion pressures were recorded while arteries were irradiated at 355 nm The time to reach maximum relaxation was longer for [RuII(NO2)(bpy)(terpy)]+ complex (ca. 50 min, n = 6) than for cis-[Ru(NO2)L(bpy)2]+ with L = py and 4-pic complex (ca. 28 min, n = 6) and cis-[Ru(NO2)(bpy)2 (pz)]2+ complex (ca. 24 min, n = 5).  相似文献   

7.
Reaction of [Ru(2,2′-bipyridine)(2,2′:6′,2″-terpyridine)Cl]PF6 (abbreviated to [Ru(bipy)(terpy)Cl]PF6) with 0.5 equiv of the bidentate ligand L produces the dinuclear complexes [{Ru(bipy)(terpy)}2(μ-L)](PF6)4 (L = 4,4′-bipyridine 1, 1,4-diisocyanobenzene 2 and pyrazine 3) in moderate yields. Treating [Ru(bipy)(terpy)Cl]PF6 with equal molar of 1,4-diisocyanobenzene affords [Ru(bipy)(terpy)(CNC6H4NC)](PF6)2 (2a). These new complexes have been characterized by mass, NMR, and UV-Vis spectroscopy, and the structures of 1-3 determined by an X-ray diffraction study. Cyclic voltammetric studies suggest that metal communication between the two ruthenium ions increases from 1 to 2 to 3.  相似文献   

8.
The synthesis, electrochemistry, spectroscopy and electrogenerated chemiluminescence (ECL) of five bis-bipyridine ruthenium(II) complexes containing acetylacetonate complexes are reported. More specifically, (bpy)2Ru(BA)2(PF6) (bpy = 2,2′-bipyridine; BA = benzoylacetonate), (bpy)2Ru(TTFA)(PF6) (TTFA =  thenoyltrifluoroacetonate), (bpy)2Ru(TFPB)(PF6) (TFPB = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate), (bpy)2Ru(TFPD)(PF6) (TFPD =  1,1,1-trifluoro-2-4-pentanedionate), and (bpy)2Ru(DBM)(PF6) (DBM = dibenzoylmethide) display UV-Vis, photoluminescence, electrochemical and ECL properties characteristic of ruthenium bipyridyl complexes. All complexes display absorptions in the UV and visible regions of the spectra, with visible absorptions ranging from 350 to 700 nm, typical of metal-to-ligand charge transfer (MLCT) transitions. Photoluminescence emission maxima are also characteristic of MLCT transitions with wavelength maxima from 575 to 600 nm depending on the nature of the acetylacetonate ligand. ECL efficiencies for the complexes (?ecl ∼ 0.013-0.051) are much lower than a standard (?ecl = 1) with electron-withdrawing substituents resulting in lower efficiencies.  相似文献   

9.
Two new mononuclear mixed-ligand ruthenium(II) complexes with acetylacetonate ion (2,4-pentanedionate, acac) and functionalized bipyridine (bpy) in position 4, [Ru(bpyBr)2(acac)](PF6) (2; bpyBr = 4-Bromo-2,2′-bipyridine, acac = 2,4-pentanedionate ion) and [Ru(bpyOH)2(acac)](PF6) (3; bpyOH = 4-[2-methyl-3-butyn-2-ol]-2,2′-bipyridine) were prepared as candidates for building blocks. The 1H NMR, 13C NMR, UV-Vis, electrochemistry and FAB mass spectral data of these complexes are presented.  相似文献   

10.
Ferromagnetic dicopper(II) complexes [Cu2(μ-O2CCH3)(μ-OH)(L)2(μ-L1)](PF6)2, where L = 1,10-phenanthroline (phen), L1 = H2O in 1 and L = dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq), L1 = CH3CN in 2, are prepared and structurally characterized. Crystals of 1 and 2 belong to the monoclinic space group of P21/n and P21/m, respectively. The copper(II) centers display distorted square-pyramidal geometry having a phenanthroline base and two oxygen atoms of the bridging hydroxo and acetate group in the basal plane. The fifth coordination site has weak axially bound bridging solvent molecule H2O in 1 and CH3CN in 2. The Cu···Cu distances are 3.034 and 3.046 Å in 1 and 2, respectively. The complexes show efficient hydrolytic cleavage of supercoiled pUC19 DNA as evidenced from the mechanistic studies that include T4 DNA ligase experiments. The binuclear complexes form monomeric copper(II) adducts [Cu(L)2(BNPP)](PF6) (L = phen, 3; dpq, 4) with bis(4-nitrophenyl)phosphate (BNPP) as a model phosphodiester. The crystal structures of 3 and 4 reveal distorted trigonal bipyramidal geometry in which BNPP binds through the oxygen atom of the phosphate. The kinetic data of the DNA cleavage reactions of the binuclear complexes under pseudo- and true-Michaelis-Menten conditions indicate remarkable enhancement in the DNA hydrolysis rate in comparison to the control data.  相似文献   

11.
The stability constants of the mixed-ligand complexes formed between Cu(Arm)2+, where Arm = 2,2′-bipyridine (Bpy) or 1,10-phenanthroline (Phen), and the monoanion or the dianion of 9-[2-(phosphonomethoxy)ethyl]-2-aminopurine (PME2AP), a structural isomer of the antivirally active 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA), were determined by potentiometric pH titrations in aqueous solution at 25 °C and I = 0.1 M (NaNO3). Detailed stability constant comparisons reveal that in the monoprotonated ternary Cu(Arm)(H;PME2AP)+ complexes the proton is at the phosphonate group and that stacking between Cu(Arm)2+ and H(PME2AP) plays a significant role. The ternary Cu(Arm)(PME2AP) complexes are considerably more stable than the corresponding Cu(Arm)(R-PO3) species, where represents a phosph(on)ate ligand with a group R that is unable to participate in any kind of interaction within the complexes. The increased stability is attributed to intramolecular stack formation in the Cu(Arm)(PME2AP) complexes and also, to a smaller extent, to the formation of 5-membered chelates involving the ether-oxygen present in the residue of PME2AP2−. This latter interaction was previously quantified by studying ternary Cu(Arm)(PME) complexes (PME2− = dianion of (phosphonomethoxy)ethane), which can form the 5-membered chelates but where no intramolecular ligand-ligand stacking is possible. Application of these results allows a quantitative analysis of the intramolecular equilibria involving three structurally different Cu(Arm)(PME2AP) species; e.g., about 5% of the Cu(Bpy)(PME2AP) system exist with the metal ion solely coordinated to the phosphonate group, 15% as a 5-membered chelate involving the ether-oxygen atom of the residue, and 80% with an intramolecular π-π stack between the purine moiety of PME2AP2− and the aromatic rings of Bpy. Finally, comparison of the stacking properties of PME2AP2− and PMEA2− in their ternary complexes reveals that stacking is somewhat more pronounced in the Cu(Arm)(PMEA) than in the Cu(Arm)(PME2AP) species. Speculatively, this reduced stacking intensity, together with a different hydrogen-bonding pattern, could well lead to a different positioning of the 2-aminopurine moiety (compared to the adenine residue) in the active site cavity of nucleic acid polymerases and thus be responsible for the reduced antiviral activity of PME2AP compared with that of PMEA.  相似文献   

12.
We report here the synthesis, characterisation, electrochemical, photophysical and protein-binding properties of four luminescent ruthenium(II) polypyridine indole complexes [Ru(bpy)2(L1)](PF6)2 (1), [Ru(bpy)2(L2)](PF6)2 (2), [Ru(L1)3](PF6)2 (1a), and [Ru(L2)3](PF6)2 (2a) (bpy = 2,2′-bipyridine; L1 = 4-(N-(2-indol-3-ylethyl)amido)-4′-methyl-2,2′-bipyridine; L2 = 4-(N-(6-N-(2-indol-3-ylethyl)hexanamidyl)amido)-4′-methyl-2,2′-bipyridine). Their indole-free counterparts, [Ru(bpy)2(L3)](PF6)2 (3) and [Ru(L3)3](PF6)2 (3a) (L3 = 4-(N-(ethyl)amido)-4′-methyl-2,2′-bipyridine), have also been synthesised for comparison purposes. Cyclic voltammetric studies revealed ruthenium-based oxidation at ca. +1.3 V versus SCE and diimine-based reductions at ca. −1.20 to −2.28 V. The indole moieties of complexes 1, 2, 1a and 2a displayed an irreversible wave at ca. +1.1 V versus SCE. All the ruthenium(II) complexes exhibited intense and long-lived orange-red triplet metal-to-ligand charge-transfer 3MLCT (dπ(Ru) → π*(L1-L3)) luminescence upon visible-light irradiation in fluid solutions at 298 K and in alcohol glass at 77 K. The binding of the indole-containing complexes to bovine serum album (BSA) has been studied by quenching experiments and emission titrations.  相似文献   

13.
A series of crystalline PdII-based heterodimetallic acetate-bridged complexes containing the transition (MnII, CoII, NiII, CuII), post-transition (ZnII) and rare-earth (CeIV, NdIII, EuIII) metals were synthesized starting from Pd3(OOCMe)6 and the complementary metal(II, III) acetates. The crystal and molecular structures of the binuclear PdIIMII(μ-OOCMe)4L (M = Mn, Co, Ni, Zn; L = H2O, MeCN), trinuclear and tetranuclear (M = Nd, Eu) and complexes were established by X-ray diffraction.  相似文献   

14.
Cyclometalation of benzo[h]quinoline (bzqH) by [RuCl(μ-Cl)(η6-C6H6)]2 in acetonitrile occurs in a similar way to that of 2-phenylpyridine (phpyH) to afford [Ru(bzq)(MeCN)4]PF6 (3) in 52% yield. The properties of 3 containing ‘non-flexible’ benzo[h]quinoline were compared with the corresponding [Ru(phpy)(MeCN)4]PF6 (1) complex with ‘flexible’ 2-phenylpyridine. The [Ru(phpy)(MeCN)4]PF6 complex is known to react in MeCN solvent with ‘non-flexible’ diimine 1,10-phenanthroline to form [Ru(phpy)(phen)(MeCN)2]PF6, being unreactive toward ‘flexible’ 2,2′-bipyridine under the same conditions. In contrast, complex 3 reacts both with phen and bpy in MeCN to form [Ru(bzq)(LL)(MeCN)2]PF6 {LL = bpy (4) and phen (5)}. Similar reaction of 3 in methanol results in the substitution of all four MeCN ligands to form [Ru(bzq)(LL)2]PF6 {LL = bpy (6) and phen (7)}. Photosolvolysis of 4 and 5 in MeOH occurs similarly to afford [Ru(bzq)(LL)(MeCN)(MeOH)]PF6 as a major product. This contrasts with the behavior of [Ru(phpy)(LL)(MeCN)2]PF6, which lose one and two MeCN ligands for LL = bpy and phen, respectively. The results reported demonstrate a profound sensitivity of properties of octahedral compounds to the flexibility of cyclometalated ligand. Analogous to the 2-phenylpyridine counterparts, compounds 4-7 are involved in the electron exchange with reduced active site of glucose oxidase from Aspergillus niger. Structure of complexes 4 and 6 was confirmed by X-ray crystallography.  相似文献   

15.
Two new heterobimetallic complexes of rhenium(I) and ruthenium(II) [(CO)3(NN)Re(4,4′-bpy)Ru(NN)2Cl](PF6)2 and already known monometallic complexes [Cl(NN)2Ru(4,4′-bpy)](PF6) and [(CO)3(NN)Re(4,4′-bpy)](PF6) and bimetallic complexes [Cl(NN)2Ru(4,4′-bpy)Ru(NN)2Cl](PF6)2, [(CO)3(NN)Re(4,4′-bpy)Re(NN)(CO)3](PF6)2 (NN = 2,2′-bipyridine, 1,10-phenanthroline; 4,4′-bpy = 4,4′-bipyridine) are synthesized and characterized by spectral techniques. The photophysical properties of all the complexes are studied. It is found that attachment of rhenium(I) altered the photophysical characteristics of ruthenium(II). Excited state energy transfer from the rhenium(I) chromophore to the ruthenium(II) is observed upon excitation at 355 nm.  相似文献   

16.
New CuII and NiII complexes of potentially tridentate N2O Schiff base ligands 1 and 2 have been synthesised and characterised. [Cu(2)(OH2)]+ possesses a square planar geometry in the solid state whereas [Ni(1)2] possesses a distorted octahedral geometry in which the amine donors of 1 coordinate weakly to the NiII centre. EPR spectroscopy demonstrates that the N2O2 coordination sphere of [Cu(2)(OH2)]+ is retained in CH2Cl2 solution. [Cu(2)(OH2)]+ exhibits a reversible one electron oxidation at E1/2 = 0.54 V versus [Fc]+/[Fc], the product of which has been characterised by UV-Vis absorption and EPR spectroscopies. The spectroscopic signature of the oxidised product is consistent with the formation of a stable phenoxyl radical ligand bound to a CuII centre. [Ni(1)2] possesses a reversible metal-based oxidation process at E1/2 = 0.03 V versus [Fc]+/[Fc] and a further oxidation, attributed to the generation of a phenoxyl radical centre, at  = 0.44 V versus [Fc]+/[Fc]. UV-Vis absorption and EPR spectroscopic studies indicate that the lower potential process is a formal NiIII/II couple. In contrast, the pro-ligands 1H and 2H exhibit chemically irreversible oxidation processes at  = 0.42 and 0.40 V versus Fc+/Fc, respectively, and do not support the formation of stable phenoxyl radical species.  相似文献   

17.
In this work we report on the synthesis, crystal structure, and physicochemical characterization of the novel dinuclear [FeIIICdII(L)(μ-OAc)2]ClO4·0.5H2O (1) complex containing the unsymmetrical ligand H2L = 2-bis[{(2-pyridyl-methyl)-aminomethyl}-6-{(2-hydroxy-benzyl)-(2-pyridyl-methyl)}-aminomethyl]-4-methylphenol. Also, with this ligand, the tetranuclear [Fe2IIIHg2II(L)2(OH)2](ClO4)2·2CH3OH (2) and [FeIIIHgII(L)(μ-CO3)FeIIIHgII(L)](ClO4)2·H2O (3) complexes were synthesized and fully characterized. It is demonstrated that the precursor [FeIII2HgII2(L)2(OH)2](ClO4)2·2CH3OH (2) can be converted to (3) by the fixation of atmospheric CO2 since the crystal structure of the tetranuclear organometallic complex [FeIIIHgII(L)(μ-CO3)FeIIIHgII(L)](ClO4)2·H2O (3) with an unprecedented {FeIII(μ-Ophenoxo)2(μ-CO3)FeIII} core was obtained through X-ray crystallography. In the reaction 2 → 3 a nucleophilic attack of a FeIII-bound hydroxo group on the CO2 molecule is proposed. In addition, it is also demonstrated that complex (3) can regenerate complex (2) in aqueous/MeOH/NaOH solution. Magnetochemical studies reveal that the FeIII centers in 3 are antiferromagnetically coupled (J = − 7.2 cm− 1) and that the FeIII-OR-FeIII angle has no noticeable influence in the exchange coupling. Phosphatase-like activity studies in the hydrolysis of the model substrate bis(2,4-dinitrophenyl) phosphate (2,4-bdnpp) by 1 and 2 show Michaelis-Menten behavior with 1 being ~ 2.5 times more active than 2. In combination with kH/kD isotope effects, the kinetic studies suggest a mechanism in which a terminal FeIII-bound hydroxide is the hydrolysis-initiating nucleophilic catalyst for 1 and 2. Based on the crystal structures of 1 and 3, it is assumed that the relatively long FeIII…HgII distance could be responsible for the lower catalytic effectiveness of 2.  相似文献   

18.
Ternary l-glutamine (l-gln) copper(II) complexes [Cu(l-gln)(B)(H2O)](X) (B = 2,2′-bipyridine (bpy), , 1; B = 1,10-phenanthroline (phen), , 2) and [Cu(l-gln)(dpq)(ClO4)] (3) (dpq, dipyridoquinoxaline) are prepared and characterized by physicochemical methods. The DNA binding and cleavage activity of the complexes have been studied. Complexes 1-3 are structurally characterized by X-ray crystallography. The complexes show distorted square pyramidal (4+1) CuN3O2 coordination geometry in which the N,O-donor amino acid and the N,N-donor heterocyclic base bind at the basal plane with a H2O or perchlorate as the axial ligand. The crystal structures of the complexes exhibit chemically significant hydrogen bonding interactions besides showing coordination polymer formation. The complexes display a d-d electronic band in the range of 610-630 nm in aqueous-dimethylformamide (DMF) solution (9:1 v/v). The quasireversible cyclic voltammetric response observed near −0.1 V versus SCE in DMF-TBAP is assignable to the Cu(II)/Cu(I) couple. The binding affinity of the complexes to calf thymus (CT) DNA follows the order: 3 (dpq) > 2 (phen) ? 1 (bpy). Complexes 2 and 3 show DNA cleavage activity in dark in the presence of 3-mercaptopropionic acid (MPA) as a reducing agent via a mechanistic pathway forming hydroxyl radical as the reactive species. The dpq complex 3 shows efficient photo-induced DNA cleavage activity on irradiation with a monochromatic UV light of 365 nm in absence of any external reagent. The cleavage efficiency of the DNA minor groove binding complexes follows the order: 3 > 2 ? 1. The dpq complex exhibits photocleavage of DNA on irradiation with visible light of 647.1 nm. Mechanistic data on the photo-induced DNA cleavage reactions reveal the involvement of singlet oxygen (1O2) as the reactive species in a type-II pathway.  相似文献   

19.
The synthesis and characterization of several complexes of the composition [{M(terpy)}n(L)](ClO4)m (M = Pt, Pd; L = 1-methylimidazole, 1-methyltetrazole, 1-methyltetrazolate; terpy = 2,2′:6′,2″-terpyridine; n = 1, 2; m = 1, 2, 3) is reported and their applicability in terms of a metal-mediated base pair investigated. Reaction of [M(terpy)(H2O)]2+ with 1-methylimidazole leads to [M(terpy)(1-methylimidazole)](ClO4)2 (1: M = Pt; 2: M = Pd). The analogous reaction of [Pt(terpy)(H2O)]2+ with 1-methyltetrazole leads to the organometallic compound [Pt(terpy)(1-methyltetrazolate)]ClO4 (3) in which the aromatic tetrazole proton has been substituted by the platinum moiety. For both platinum(II) and palladium(II), doubly metalated complexes [{M(terpy)}2(1-methyltetrazolate)](ClO4)3 (4: M = Pt; 5: M = Pd) can also be obtained depending on the reaction conditions. In the latter two compounds, the [M(terpy)]2+ moieties are coordinated via C5 and N4. X-ray crystal structures of 1, 2, and 3 are reported. In addition, DFT calculations have been carried out to determine the energy difference between fully planar [Pd(mterpy)(L)]2+ complexes Ip-IVp (mterpy = 4′-methyl-2,2′:6′,2″-terpyridine; L = 1-methylimidazole-N3 (I), 1-methyl-1,2,4-triazole-N4 (II), 1-methyltetrazole-N3 (III), or 3-methylpyridine-N1 (IV)) and the respective geometry-optimized structures Io-IVo. Whereas this energy difference is larger than 70 kJ mol−1 for compounds I, II, and IV, it amounts to only 0.8 kJ mol−1 for the tetrazole-containing complex III, which is stabilized by two intramolecular C-H?N hydrogen bonds. Of all complexes under investigation, only the terpyridine-metal ion-tetrazole system with N3-coordinated tetrazole appears to be suited for an application in terms of a metal-mediated base pair in a metal-modified oligonucleotide.  相似文献   

20.
Two new binuclear copper complexes, [Cu2(oxpn)(bpy)(pic)(H2O)](pic) (1) and [Cu2(oxpn)(Me2bpy)(pic)](pic) (2) [H2oxpn = N,N′-bis(3-aminopropyl)oxamide; Hpic = 2,4,6-trinitrophenol; bpy = 2,2′-bipyridine; Me2bpy = 4,4′-dimethyl-2,2′-bipyridine], have been synthesized and characterized by elemental analyses, conductivity measurements, IR, UV-visible spectroscopy and single crystal X-ray analyses. Both complexes have similar molecular structures. In complex 1, the central two Cu(II) atoms are bridged by cis-oxpn2− with the Cu1-Cu2 separation of 5.221 Å and the polyhedron of each copper atom is a square-pyramid. Similarly, complex 2 is a cis-oxpn2−-bridged binuclear complex with the Cu1-Cu2 separation of 5.196 Å. Cu1(II) central atom situated in a tetrahedral geometry is four-coordinated and Cu(II) atom situated in a square-pyramidal geometry is five-coordinated. Hydrogen bonding interactions and π-π stacking interactions link the binuclear copper complex 1 or 2 into a 2D infinite network. The antibacterial assays indicate that the two complexes showed better activities than their ligands. The interactions of the two binuclear complexes with herring sperm DNA (HS-DNA) have been studied by UV absorption titration, fluorescence titration and viscosity measurements. The results suggest that the two binuclear complexes bind to HS-DNA via an intercalative mode.  相似文献   

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