Rhenium(I) polypyridine biotin isothiocyanate complexes as the first luminescent biotinylation reagents: synthesis, photophysical properties, biological labeling, cytotoxicity, and imaging studies

We report here the design of the first class of luminescent biotinylation reagents derived from rhenium(I) polypyridine complexes. These complexes [Re(N-N)(CO)(3)(py-biotin-NCS)](PF(6)) (py-biotin-NCS = 3-isothiocyanato-5-(N-((2-biotinamido)ethyl)aminocarbonyl)pyridine; N-N = 1,10-phenanthroline (phen) (1a), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me(4)-phen) (2a), 4,7-diphenyl-1,10-phenanthroline (Ph(2)-phen) (3a)), containing a biotin unit and an isothiocyanate moiety, have been synthesized from the precursor amine complexes [Re(N-N)(CO)(3)(py-biotin-NH(2))](PF(6)) (py-biotin-NH(2) = 3-amino-5-(N-((2-biotinamido)ethyl)aminocarbonyl)pyridine; N-N = phen (1c), Me(4)-phen (2c), Ph(2)-phen (3c)). To investigate the amine-specific reactivity of the isothiocyanate complexes 1a-3a, they have been reacted with a model substrate ethylamine, resulting in the formation of the thiourea complexes [Re(N-N)(CO)(3)(py-biotin-TU-Et)](PF(6)) (py-biotin-TU-Et = 3-ethylthioureidyl-5-(N-((2-biotinamido)ethyl)aminocarbonyl)pyridine; N-N = phen (1b), Me(4)-phen (2b), Ph(2)-phen (3b)). All the rhenium(I) complexes have been characterized, and their photophysical properties have been studied. The avidin-binding properties of the thiourea complexes 1b-3b have been examined by the 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assay. Titration results indicated that the complexes exhibited emission enhancement by ca. 1.4-1.5-fold upon binding to avidin, and the lifetimes were elongated to ca. 0.8-2.0 micros. Additionally, we have biotinylated bovine serum albumin (BSA) with the isothiocyanate complexes. All the resultant rhenium-BSA bioconjugates displayed intense and long-lived orange-yellow to greenish-yellow emission upon irradiation in aqueous buffer under ambient conditions. The avidin-binding properties of the bioconjugates have been investigated using the HABA assay. Furthermore, the cytotoxicity of the thiourea complexes 1b-3b toward the HeLa cells has been examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC50 values were determined to be ca. 17.5-28.5 microM, which are comparable to that of cisplatin (26.7 microM) under the same conditions. The cellular uptake of complex 3b has been investigated by fluorescence microscopy, and the results showed that the complex was localized in the perinuclear region after interiorization.     

Synthesis, characterization, crystal structure, and electrochemical, photophysical, and protein-binding properties of luminescent rhenium(I) diimine indole complexes

We report the synthesis, characterization, and photophysical and electrochemical properties of a series of luminescent rhenium(I) diimine indole complexes, [Re(N-N)(CO)3(L)](CF3SO3) (N-N = 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4-phen), L = N-(3-pyridoyl)tryptamine (py-3-CONHC2H4-indole) (1a), N-[N-(3-pyridoyl)-6-aminohexanoyl]tryptamine, (py-3-CONHC5H10CONHC2H4-indole) (1b); N-N = 1,10-phenanthroline (phen), L = py-3-CONHC2H4-indole (2a), py-3-CONHC5H10CONHC2H4-indole (2b); N-N = 2,9-dimethyl-1,10-phenanthroline (Me2-phen), L = py-3-CONHC2H4-indole (3a), py-3-CONHC5H10CONHC2H4-indole (3b); N-N = 4,7-diphenyl-1,10-phenanthroline (Ph2-phen), L = py-3-CONHC2H4-indole (4a), py-3-CONHC5H10CONHC2H4-indole (4b)), and their indole-free counterparts, [Re(N-N)(CO)3(py-3-CONH-Et)](CF3SO3) (py-3-CONH-Et = N-ethyl-(3-pyridyl)formamide; N-N = Me4-phen (1c), phen (2c), Me2-phen (3c), Ph2-phen (4c)). The X-ray crystal structure of complex 3a has also been investigated. Upon irradiation, most of the complexes exhibited triplet metal-to-ligand charge-transfer (3MLCT) (d pi(Re) --> pi*(diimine)) emission in fluid solutions at 298 K and in low-temperature glass. However, the structural features and long emission lifetimes of the Me4-phen complexes in solutions at room temperature suggest that the excited state of these complexes exhibited substantial triplet intraligand (3IL) (pi --> pi*) (Me4-phen) character. The binding interactions of these complexes to indole-binding proteins including bovine serum albumin and tryptophanase have been examined.     

Design of rhenium(I) polypyridine biotin complexes as a new class of luminescent probes for avidin

This paper describes the design of a series of luminescent rhenium(I) polypyridine biotin complexes containing different spacer-arms, [Re(N-N)(CO)3 (py-4-CH2-NH-biotin)](PF6) (py-4-CH2-NH-biotin = 4-(biotinamidomethyl)pyridine; N-N = 1,10-phenanthroline, phen (1a), 3,4,7,8-tetramethyl-1,10-phenanthroline, Me4-phen (2a), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, Me2-Ph2-phen (3a), dipyrido[3,2-f:2',3'-h]quinoxaline, dpq (4a)), [Re(N-N)(CO)3 (py-3-CO-NH-en-NH-biotin)](PF6) (py-3-CO-NH-en-NH-biotin = 3-(N-((2-biotinamido)ethyl)amido)pyridine; N-N = phen (1b), Me4-phen (2b), Me2-Ph2-phen (3b), dpq (4b)), and [Re(N-N)(CO)3 (py-4-CH2-NH-cap-NH-biotin)](PF6) (py-4-CH2-NH-cap-NH-biotin = 4-(N-((6-biotinamido)hexanoyl)aminomethyl)pyridine; N-N = phen (1c), Me4-phen (2c), Me2-Ph(2)-phen (3c), dpq (4c)). Upon irradiation, all of the rhenium(I)-biotin complexes exhibited intense and long-lived triplet metal-to-ligand charge-transfer (3MLCT) (d pi(Re) --> pi* (diimine)) emission in fluid solutions at 298 K. The interactions of these biotin-containing complexes with avidin have been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, emission titrations, and competitive association and dissociation assays. On the basis of the results of these experiments, homogeneous assays for biotin and avidin have been designed.     

Preparation of stannyl complexes of ruthenium and osmium stabilised by polypyridine and phosphite ligands

Trichlorostannyl complexes [M(SnCl3)(bpy)2P]BPh4 [M = Ru, P = P(OEt)(3), 1a PPh(OEt)2 1b; M = Os, P = P(OEt)3 2; bpy = 2,2'-bipyridine] were prepared by allowing chloro complexes [MCl(bpy)2P]BPh4 to react with SnCl2 in 1,2-dichloroethane. Bis(trichlorostannyl) compounds Ru(SnCl3)2(N-N)P2 [N-N = bpy, P = P(OEt)3 3a, PPh(OEt)2 3b; N-N = 1,10-phenanthroline (phen), P = P(OEt)3 4] were also prepared by reacting [RuCl(N-N)P3]BPh4 precursors with SnCl2.2H2O in ethanol. Treatment of both mono- 1a, 2 and bis 3a trichlorostannyl complexes with NaBH4 afforded mono- and bis(trihydridestannyl) derivatives [M(SnH3)(bpy)2P]BPh4 5, 6 and Ru(SnH3)2(bpy)P2 7[P = P(OEt)3], respectively. Treatment of 1a, 2 with MgBrMe gave the trimethylstannyl complexes [M(SnMe3)(bpy)2P]BPh4 8, 9 and treatment of 3a afforded the bis(stannyl) Ru(SnClMe2)2(bpy)P2 10 derivative. Alkynylstannyl complexes [M{Sn(C triple bond CR)3}(bpy)2P]BPh4 11-13 and Ru[Sn(C triple bond CR)3]2(N-N)P2 14-17(R = p-tolyl, Bu t; N-N = bpy, phen) were also prepared by allowing trichlorostannyl compounds 1-4 to react with Li+[RC triple bond C]* in thf. The complexes were characterised spectroscopically and by the X-ray crystal structure determination of [Ru(SnMe3)(bpy)2{P(OEt)3}]BPh4 derivative.     

Synthesis, functionalization, characterization, and photophysical study of carbonyl-containing isocyano rhenium(I) diimine complexes

New classes of tunable rhenium(I) diimine luminophores with formula of [Re(CO)(CNR)(3)(N-N)]PF(6) and [Re(CO)(L(x))(CNC(6)H(4)Cl-4)(2)(1,10-phenanthroline)]PF(6), (R = C(6)H(5), 4-BrC(6)H(4), 4-ClC(6)H(4), 4-MeOC(6)H(4), 2,6-(i)Pr(2)C(6)H(3); N-N = 1,10-phenanthroline, 5,6-dibromo-1,10-phenanthroline, 4,4'-di-tert-butyl-2,2'-bipyridine; L(x) = MeCN, pyridine and PPh(3)) have been synthesized. Different synthetic routes including photo-ligand substitution and thermal carbonyl ligand substitution through the oxidative decarbonylation with trimethyl amine N-oxide, for the facial and meridional isomeric forms of [Re(CO)(CNR)(3)(N-N)]PF(6) were investigated. On the basis of these synthetic strategies, different ligand modification and functionalization of the rhenium(I) diimine luminophores with tailored excited state properties could be readily achieved. The structures of both facial and meridional conformations of [Re(CO)(CNR)(3)(N-N)]PF(6) and the complex precursors fac-[Re(CO)(3)(CNC(6)H(3)(i)Pr-2,6)(3)]OTf were determined by X-ray crystallography. These complexes display an orange to red (3)MLLCT [dπ(Re) → π*(N-N)] phosphorescence at room temperature. Detailed photophysical investigations revealed that the physical, photophysical, electrochemical, and excited state properties can be fine-tuned and tailored through the modifications of the substituents on isocyanide or diimine ligands.     

Synthesis,photophysical and electrochemical properties,and biological labeling studies of cyclometalated iridium(III) bis(pyridylbenzaldehyde) complexes: novel luminescent cross-linkers for biomolecules

We report the synthesis, characterization, photophysical, and electrochemical properties of a series of luminescent cyclometalated iridium(III) complexes containing two aldehyde functional groups [Ir(pba)(2)(N-N)](PF(6)) (Hpba=4-(2-pyridyl)benzaldehyde; N-N=2,2'-bipyridine, bpy (1), 1,10-phenanthroline, phen (2), 3,4,7,8-tetramethyl-1,10-phenanthroline, 3,4,7,8-Me(4)-phen (3), 4,7-diphenyl-1,10-phenanthroline, 4,7-Ph(2)-phen (4)). The X-ray crystal structure of complex 1 has been investigated. Upon photoexcitation, complexes 1-4 exhibit intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The luminescence is assigned to a triplet intra-ligand ((3)IL) excited state associated with the pba(-) ligand, probably with mixing of some triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir)-->pi*(pba(-))) character. Since each of these complexes possesses two aldehyde groups, which can react with the primary amine groups of biomolecules to form stable secondary amines after reductive amination, we have investigated the possibility of these complexes as novel luminescent cross-linkers for biological substrates. L-Alanine has been labeled with complexes 1-4 to give the luminescent bioconjugates 1-(Ala)(2)-4-(Ala)(2). These conjugates show strong photoluminescence with long emission lifetimes under ambient conditions. On the basis of the emission energy trend, the excited state of these luminescent bioconjugates is likely to bear a high parentage of (3)MLCT (dpi(Ir)-->pi*(N-N)) character. In addition, the glycoprotein avidin (Av) has also been conjugated with complexes 1-4 to give the bioconjugates 1-Av-4-Av. Upon photoexcitation, these bioconjugates also display intense and long-lived (3)MLCT (dpi(Ir)-->pi*(N-N)) emission in aqueous buffer at 298 K. Furthermore, a heterogeneous competitive assay for biotin has been developed using 2-Av and biotinylated microspheres. We have shown that complexes 1-4 represent a new class of multicolor luminescent cross-linkers for biomolecular species.     

Synthesis and spectroelectrochemical studies of mixed heteroleptic chelate complexes of ruthenium(II) with 1,8-bis(2-pyridyl)-3,6-dithiaoctane (pdto) and substituted 1,10-phenanthrolines

Reaction of dichlorotris(triphenylphosphine) ruthenium(II) [RuCl(2)(PPh(3))(3)] with 1,8-bis(2-pyridyl)-3,6-dithiaoctane (pdto), a (N(2)S(2)) tetradentate donor, yields a new compound [Ru(pdto)(PPh(3))Cl]Cl (1), which has been fully characterized. (1)H and (31)P NMR studies of 1 in acetonitrile at several temperatures show the substitution of both coordinated chloride and triphenylphosphine with two molecules of acetonitrile, as confirmed by the isolation of the complex [Ru(pdto)(CH(3)CN)(2)]Cl(2) (2). Cyclic voltammetric and spectroelectrochemical techniques allowed us to determine the electrochemical behavior of compound 1. The substitution of the chloride and triphenylphosphine by acetonitrile molecules in the Ru(II) coordination sphere of compound 1 was also established by electrochemical studies. The easy substitution of this complex led us to use it as starting material to synthesize the substituted phenanthroline coordination compounds with (pdto) and ruthenium(II), [Ru(pdto)(4,7-diphenyl-1,10-phenanthroline)]Cl(2).4H(2)O (3), [Ru(pdto)(1,10-phenanthroline)]Cl(2).5H(2)O (4), [Ru(pdto)(5,6-dimethyl-1,10-phenanthroline)]Cl(2).5H(2)O (5), [Ru(pdto)(4,7-dimethyl-1,10-phenanthroline)]Cl(2).3H(2)O (6), and [Ru(pdto)(3,4,7,8-tetramethyl-1,10-phenanthroline)]Cl(2).4H(2)O (7). These compounds were fully characterized, and the crystal structure of 4 was obtained. Cyclic voltammetric and spectroelectrochemical techniques allowed us to determine their electrochemical behavior. The electrochemical oxidation processes in these compounds are related to the oxidation of ionic chlorides, and to the reversible transformation from Ru(II) to Ru(III). On the other hand, a single reduction process is associated to the reduction of the substituted phenanthroline in the coordination compound. The E(1/2) (phen/phen(-)) and E(1/2) (Ru(II)/Ru(III)) for the compounds (3-7) were evaluated, and, as expected, the modification of the substituted 1,10-phenanthrolines in the complexes also modifies the redox potentials. Correlations of both electrochemical potentials with pK(a) of the free 1,10-phenathrolines, lambda(max) MLCT transition band, and chemical shifts of phenanthrolines in these complexes were found, possibly as a consequence of the change in the electron density of the Ru(II) and the coordinated phenanthroline.     

Synthesis of heteroleptic bis(diimine)carbonylchlororuthenium(II) complexes from photodecarbonylated precursors

The reactions of bidentate diimine ligands (L2) with binuclear [Ru(L1)(CO)Cl2]2 complexes [L1 not equal to L2 = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (4,4'-Me2bpy), 5,5'-dimethyl-2,2'-bipyridine (5,5'-Me2bpy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (4,7-Me2phen), 5,6-dimethyl-1,10-phenanthroline (5,6-Me2phen), di(2-pyridyl)ketone (dpk), di(2-pyridyl)amine (dpa)] result in cleavage of the dichloride bridge and the formation of cationic [Ru(L1)(L2)(CO)Cl]+ complexes. In addition to spectroscopic characterization, the structures of the [Ru(bpy)(phen)(CO)Cl]+, [Ru(4,4'-Me2bpy)(5,6-Me2phen)(CO)Cl]+ (as two polymorphs), [Ru(4,4'-Me2bpy)(4,7-Me2phen)(CO)Cl]+, [Ru(bpy)(dpa)(CO)Cl]+, [Ru(5,5'-Me2bpy)(dpa)(CO)Cl]+, [Ru(bpy)(dpk)(CO)Cl]+, and [Ru(4,4'-Me2bpy)(dpk)(CO)Cl]+ cations were confirmed by single crystal X-ray diffraction studies. In each case, the structurally characterized complex had the carbonyl ligand trans to a nitrogen from the incoming diimine ligand, these complexes corresponding to the main isomers isolated from the reaction mixtures. The synthesis of [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)(NO3)]+ from [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)Cl]+ and AgNO3 demonstrates that exchange of the chloro ligand can be achieved.     

Synthesis, characterization, DNA interaction and cleavage, and in vitro cytotoxicity of copper(II) mixed-ligand complexes with 2-phenyl-3-hydroxy-4(1H)-quinolinone

A series of mixed-ligand complexes [Cu(qui)(L)]NO(3)·xH(2)O (1-6), where Hqui = 2-phenyl-3-hydroxy-4(1H)-quinolinone, L = 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), bis(2-pyridyl)amine (ambpy) (3), 5-methyl-1,10-phenanthroline (mphen) (4), 5-nitro-1,10-phenanthroline (nphen) (5) and bathophenanthroline (bphen) (6), have been synthesized and fully characterized. The X-ray structures of [Cu(qui)(phen)]NO(3)·H(2)O (2) and [Cu(qui)(ambpy)]NO(3) (3a) show a slightly distorted square-planar geometry in the vicinity of the central copper(II) atom. An in vitro cytotoxicity study of the complexes found significant activity against human osteosarcoma (HOS) and human breast adenocarcinoma (MCF7) cell lines, with the best results for complex 6, where IC(50) equals to 2.1 ± 0.2 μM, and 2.2 ± 0.4 μM, respectively. The strong interactions of the complexes with calf thymus DNA (CT-DNA) and high ability to cleave pUC19 DNA plasmid were found. A correlation has been found between the in vitro cytotoxicity and DNA cleavage studies of the complexes.     

Long-lived palladium catalysts for CO/vinyl arene polyketones synthesis: a solution to deactivation problems

A series of cationic palladium complexes of general formula [Pd(Me)(MeCN)(N-N)][PF(6)] (N-N = (phen) 1 a, 4,7-dichloro-1,10-phenanthroline (4,7-Cl(2)-phen) 2 a, 4,7-diphenyl-1,10-phenanthroline (4,7-Ph(2)-phen) 3 a, 4-methyl-1,10-phenanthroline (4-Me-phen) 4 a, 4,7-dimethyl-1,10-phenanthroline (4,7-Me(2)-phen) 5 a, 5,5,6,6-tetrafluoro-5,6-dihydro-1,10-phenanthroline (F(4)-phen) 6 a, containing different substituted phenanthroline ligands, have been prepared from the corresponding neutral chloro derivatives [Pd(Me)(Cl)(N-N)], (1 b-6 b). The X-ray crystal structure of [Pd(Cl)(2)(4,7-Cl(2)-phen)] (2 b') was determined. DFT calculations show that the electron density on the metal is tuned by the substituents on the ligands. The catalytic behavior of complexes 1 a-6 a in the CO/styrene and CO/p-Me-styrene copolymerizations was studied in detail, showing that the generated catalysts are active for at least 90 h, yielding copolymers of high molecular weight. A firm correlation between the electron density on palladium on the one hand and the catalytic activity of the complexes and the molecular weight and the stereochemistry of the polyketones synthesized on the other hand has been established: the catalyst containing the F(4)-phen is thus far the most active among those tested, yielding the syndiotactic CO/styrene copolymer with a stereoregularity of 96 % (uu triad) and with an M(w) value of 1 000 000.     

New luminescent cyclometalated iridium(III) diimine complexes as biological labeling reagents

We report the synthesis, characterization, and photophysical and electrochemical properties of thirty luminescent cyclometalated iridium(III) diimine complexes [Ir(N-C)(2)(N-N)](PF(6)) (HN-C = 2-phenylpyridine, Hppy; 2-(4-methylphenyl)pyridine, Hmppy; 3-methyl-1-phenylpyrazole, Hmppz; 7,8-benzoquinoline, Hbzq; 2-phenylquinoline, Hpq; N-N = 4-amino-2,2'-bipyridine, bpy-NH(2); 4-isothiocyanato-2,2'-bipyridine, bpy-ITC; 4-iodoacetamido-2,2'-bipyridine, bpy-IAA; 5-amino-1,10-phenanthroline, phen-NH(2); 5-isothiocyanato-1,10-phenanthroline, phen-ITC; 5-iodoacetamido-1,10-phenanthroline, phen-IAA). The X-ray crystal structure of [Ir(mppz)(2)(bpy-NH(2))](PF(6)) has also been investigated. Upon irradiation, all the complexes display intense and long-lived luminescence under ambient conditions and in 77-K glass. On the basis of the photophysical and electrochemical data, the emission of most of these complexes is assigned to an excited state of predominantly triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir) --> pi(N-N)) character. In some cases, triplet intraligand ((3)IL) (pi --> pi)(N-N or N-C(-)) excited states have also been identified. In view of the specific reactivity of the isothiocyanate and iodoacetamide moieties toward the primary amine and sulfhydryl groups, respectively, we have labeled various biological molecules with a selection of these luminescent iridium(III) complexes. The photophysical properties of the luminescent conjugates have been investigated. In addition, a heterogeneous assay for digoxin has also been designed on the basis of the recognition of biotinylated anti-digoxin by avidin labeled with one of the luminescent iridium(III) complexes.     

Synthesis, anticancer and antibacterial activity of some novel mononuclear Ru(II) complexes

In search of potential anticancer drug candidates in ruthenium complexes, a series of mononuclear ruthenium complexes of the type [Ru(phen)(2)(nmit)]Cl(2) (Ru1), [Ru(bpy)(2)(nmit)]Cl(2) (Ru2), [Ru(phen)(2)(icpl)]Cl(2) (Ru3), Ru(bpy)(2)(icpl)]Cl(2) (Ru4) (phen=1,10-phenanthroline; bpy=2,2'-bipyridine; nmit=N-methyl-isatin-3-thiosemicarbazone, icpl=isatin-3-(4-Cl-phenyl)thiosemicarbazone) and [Ru(phen)(2)(aze)]Cl(2) (Ru5), [Ru(bpy)(2)(aze)]Cl(2) (Ru6) (aze=acetazolamide) and [Ru(phen)(2)(R-tsc)](ClO(4))(2) (R=methyl (Ru7), ethyl (Ru8), cyclohexyl (Ru9), 4-Cl-phenyl (10), 4-Br-phenyl (Ru11), and 4-EtO-phenyl (Ru12), tsc=thiosemicarbazone) were prepared and characterized by elemental analysis, FTIR, (1)H-NMR and FAB-MS. Effect of these complexes on the growth of a transplantable murine tumor cell line (Ehrlich Ascites Carcinoma) and their antibacterial activity were studied. In cancer study the effect of hematological profile of the tumor hosts have also been studied. In the cancer study, the complexes Ru1-Ru4, Ru10 and Ru11 have remarkably decreased the tumor volume and viable ascitic cell count as indicated by trypan blue dye exclusion test (p<0.05). Treatment with the ruthenium complexes prolonged the lifespan of Ehrlich Ascites Carcinoma (EAC) bearing mice. Tumor inhibition by the ruthenium chelates was followed by improvements in hemoglobin, RBC and WBC values. All the complexes showed antibacterial activity, except Ru5 and Ru6. Thus, the results suggest that these ruthenium complexes have significant antitumor property and antibacterial activity. The results also reflect that the drug does not adversely affect the hematological profiles as compared to that of cisplatin on the host.     

Electron transfer reactions of tris(polypyridine)cobalt(III) complexes, [Co(N-N)3]3+, with verdazyl radicals in acetonitrile solution

The kinetics and mechanisms of the reactions of 3-(4-X)-phenyl-1,5-diphenyl-verdazyl radicals where X = Cl, H, CH3 and CH3O with [Co(N-N)3]3+, N-N = 2,2'-bipyridyl (bpy), 1,10-phenanthroline (phen) and 4,7-dimethyl-1,10-phenanthroline (4,7-Me2phen), have been investigated in acetonitrile at 25 degrees C and ionic strength 0.05 mol dm(-3)(nC4H9)4NPF6 using stopped flow spectrophotometry. In all cases, transfer of one electron from the radical takes place resulting in the production of a Co(II) species and a verdazylium cation. The electron transfer occurs by an outer-sphere mechanism and the reactions appear to be consistent with Marcus theory. The self-exchange rate constants for the verdazyl-verdazylium cation have been estimated and are of the order of 3.4(+/-1.9) x 10(7) dm(3) mol(-1) s(-1). This rate constant is consistent with the fact that the reactions of [Ru(bpy)3]3+ with verdazyl radicals are too rapid to be investigated by stopped flow spectrophotometry.     

Divalent osmium complexes: synthesis,characterization, strong red phosphorescence,and electrophosphorescence

We report new divalent osmium complexes that feature strong red metal-to-ligand-charge-transfer (MLCT) phosphorescence and electrophosphorescence. The general formula of the complexes is Os(II)(N-N)(2)L-L, where N-N is either a bipyridine or a phenanthroline and L-L is either a phosphine or an arsine. New polypyridyl ligands synthesized are 4,4'-di(biphenyl)-2,2'-bipyridine (15) and 4,4'-di(diphenyl ether)-2,2'-bipyridine (16), and the 1,10-phenanthroline derivatives synthesized are 4,7-bis(p-methoxyphenyl)-1,10-phenanthroline (17), 4,7-bis(p-bromophenyl)-1,10-phenanthroline (18), 4,7-bis(4'-phenoxybiphen-4-yl)-1,10-phenanthroline (19), and 4,7-bis(4-naphth-2-ylphenyl)-1,10-phenanthroline (20). 4,4'-Diphenyl-2,2'-bipyridine (21) and 4,7-diphenyl-1,10-phenanthroline (22) were also used in these studies. Strong pi-acid ligands used were 1,2-bis(diphenylarseno)ethane (23), cis-1,2-bis(diphenylphosphino)ethylene (24), and cis-1,2-vinylenebis(diphenylarsine) (25). Ligand 25 is used for the first time in these types of luminescent osmium complexes. These compounds feature strong MLCT absorption bands in the visible region and strong red phosphorescent emission ranging from 611 to 651 nm, with quantum efficiency up to 45% in ethanol solution at room temperature. Red organic light-emitting diodes (OLEDs) were successfully fabricated by doping the Os(II) complexes into blend of poly(N-vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD). Brightness over 1400 cd/m(2) for a double-layer device has been reached, with a turn-on voltage of 8 V. The maximum external quantum efficiency was 0.64%. Commission Internationale de l'Eclairage (CIE) chromaticity coordinates (x, y) of the red electrophosphorescence from the complexes are (0.65, 0.34), which indicates pure red emission.     

Preparation and reactivity of mixed-ligand ruthenium(II) hydride complexes with phosphites and polypyridyls

Chloro complexes [RuCl(N-N)P3]BPh4 (1-3) [N-N = 2,2'-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5'-dimethyl-2,2'-bipyridine, 5,5'-Me2bpy; P = P(OEt)3, PPh(OEt)2 and PPh2OEt] were prepared by allowing the [RuCl4(N-N)].H2O compounds to react with an excess of phosphite in ethanol. The bis(bipyridine) [RuCl(bpy)2[P(OEt)3]]BPh4 (7) complex was also prepared by reacting RuCl2(bpy)2.2H2O with phosphite and ethanol. Treatment of the chloro complexes 1-3 and 7 with NaBH4 yielded the hydride [RuH(N-N)P3]BPh4 (4-6) and [RuH(bpy)2P]BPh4 (8) derivatives, which were characterized spectroscopically and by the X-ray crystal structure determination of [RuH(bpy)[P(OEt)3]3]BPh4 (4a). Protonation reaction of the new hydrides with Br?nsted acid was studied and led to dicationic [Ru(eta2-H2)(N-N)P3]2+ (9, 10) and [Ru(eta(2-H2)(bpy)2P]2+ (11) dihydrogen derivatives. The presence of the eta2-H2 ligand was indicated by a short T(1 min) value and by the measurements of the J(HD) in the [Ru](eta2-HD) isotopomers. From T(1 min) and J(HD) values the H-H distances of the dihydrogen complexes were also calculated. A series of ruthenium complexes, [RuL(N-N)P3](BPh4)2 and [RuL(bpy)2P](BPh4)2 (P = P(OEt)3; L = H2O, CO, 4-CH3C6H4NC, CH3CN, 4-CH3C6H4CN, PPh(OEt)2], was prepared by substituting the labile eta2-H2 ligand in the 9, 10, 11 derivatives. The reactions of the new hydrides 4-6 and 8 with both mono- and bis(aryldiazonium) cations were studied and led to aryldiazene [Ru(C6H5N=NH)(N-N)P3](BPh4)2 (19, 21), [[Ru(N-N)P3]2(mu-4,4'-NH=NC6H4-C6H4N=NH)](BPh4)4 (20), and [Ru(C6H5N=NH)(bpy)2P](BPh4)2 (22) derivatives. Also the heteroallenes CO2 and CS2 reacted with [RuH(bpy)2P]BPh4, yielding the formato [Ru[eta1-OC(H)=O](bpy)2P]BPh4 and dithioformato [Ru[eta1-SC(H)=S](bpy)2P]BPh4 derivatives.     

A density functional study of the reactivity and stability of mixed copper complexes. Is hardness the reason?

Mixed-ligand Cu2+ ternary complexes, formed by an aromatic diimine and a second ligand with O donor atoms, show a higher than expected stability. To understand the factors affecting the stability of these systems, we performed a density functional study of [Cu(H2O)5]2+, [Cu(N-N)(H2O)3]2+, and [Cu(N-N)(O-O)H2O] (N-N is 1,10-phenanthroline, 5-nitro-1,10-phenanthroline, or 3,4,7,8-tetramethyl-1,10-phenanthroline; and O-O is oxalate). In the present study, full geometry optimization (B3LYP/3-21G**) has been performed without symmetry constraints and a comparison with some available experimental results has been made. Bond distances, equilibrium geometries, harmonic frequencies, and net atomic charges from Mulliken populations are presented. Since the principle of hard and soft acids and bases has been widely used to explain the stability of these complexes, we also calculated and analyzed the global hardness and the local softness. The results of the global hardness do not support the commonly held idea that harder acids will preferably bind to harder ligands, while softer acids will bind to softer ligands. Interestingly, local softness and electron affinity correlate well with the formation constants of these compounds and provide an explanation of the reactivity behavior. The present results may help to rationalize the stability and reactivity of these systems.     

Photochemical expulsion of the neutral monodentate ligand L in Ru(terpy*)(diimine)(L)2+: a dramatic effect of the steric properties of the spectator diimine ligand

A series of photoreactive complexes of the type Ru(terpy*)(N-N)(L)(2+), where terpy* is 4'-(3,5-ditertiobutylphenyl)-2,2':6',2' '-terpyridine, N-N is the bidentate chelate phen or dmp (phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline), and L is the monodentate ligand dms, MeBN, or MeOBN (dms = dimethyl sulfide, MeBN = 2,6-dimethyl benzonitrile, MeOBN = 2,6-dimethoxybenzonitrile), has been synthesized and fully characterized by proton NMR spectroscopy, electrospray mass spectrometry, and UV-vis spectroscopy. The X-ray structures of four complexes were also obtained. In neat pyridine, the quantum yields for the photosubsitution of L by pyridine were measured and showed dramatic variations depending on the steric interactions between the spectator bidentate ligand and the leaving monodentate ligand L. The use of dmp instead of phen multiplied the photosubstitution efficiency by a factor of 20-50, depending on L. This effect could be qualitatively correlated to the distortions observed in the X-ray structures of the corresponding complexes. The highly distorted structure of Ru(terpy)(dmp)(dms)(PF(6))(2) showed a very high photosubsitution quantum yield phi = 0.36 in neat pyridine. The high photoreactivity of some of the compounds makes them particularly promising as components of future light-driven molecular machines.     

取代基对咪唑[4,5-f]-1,10-邻菲罗啉Ru(Ⅱ)配合物的温敏性能影响

合成了3种具有不同取代基的咪唑[4, 5-f]-1,10-邻菲罗啉配体L¹~L³及其Ru(Ⅱ)配合物[Ru(L¹)₃]、[Ru(L²)₃]和[Ru(L³)₃],并进行了表征。这些Ru(Ⅱ)配合物在溶液中具有π→π^*跃迁吸收峰和金属到配体的电荷转移跃迁(MLCT)吸收峰,其发光峰位约为590 nm左右。将Ru(Ⅱ)配合物掺杂到聚甲基丙烯酸甲酯(PMMA)中得到相应的温敏漆。Ru(Ⅱ)配合物在PMMA膜中的吸收峰精细结构消失,且在长波方向663 nm附近有新的发射峰,表明Ru(Ⅱ)配合物在PMMA膜中有聚集。温度升高后,Ru(Ⅱ)配合物在PMMA膜中的发射峰强度逐渐减弱。分别计算了在30~60 ℃和60~90 ℃区间内非辐射活化能E_nr和温度灵敏度S_T。结果表明,具有苯基取代的咪唑[4, 5-f]-1,10-邻菲罗啉配体的[Ru(L¹)₃]配合物,比咪唑[4, 5-f]-1,10-邻菲罗啉Ru(Ⅱ)配合物[Ru(L²)₃]及烷基取代基的咪唑[4, 5-f]-1,10-邻菲罗啉Ru(Ⅱ)配合物[Ru(L³)₃]具有更高的温度灵敏度。     

Complexes of a hexa-nitrile dianion with neutral, chelating co-ligands: self-assembly, structure and magnetism

Several new first-row transition-metal complexes have been synthesised by combining the polynitrile dianion HCTMCP(2-) (hexacyanotrimethylenecyclopropandiide) with neutral, chelating co-ligands; 2,2'-bipyridine, 1,10-phenanthroline and 3-(2-pyridyl)pyrazole. The products cover a remarkable range of species including mononuclear complexes, dimers, charge-separated species and coordination polymers. Complexes containing 2,2'-bipyridine take the form [Mn(2,2'-bipy)(2)(HCTMCP)](2)·2MeOH (1) or [M(2,2'-bipy)(3)](HCTMCP) (2Fe and 2Co) which are dimeric and charge-separated products, respectively. The products obtained using 1,10-phenanthroline were the discrete complex [Co(HCTMCP)(1,10-phen)(2)(H(2)O)]·H(2)O·MeCN (3) and the 1D coordination polymer [Mn(HCTMCP)(1,10-phen)(H(2)O)(MeOH)] (4). Complexes using the 3-(2-pyridyl)pyrazole co-ligand (pypzH) form similar 1D complexes to 4, namely [Mn(pypzH)(HCTMCP)(MeOH)(H(2)O)] (5) and [M(pypzH)(HCTMCP)(MeOH)(2)] (6Co and 6Fe), albeit with different hydrogen-bonding motifs between the chains. The polymeric HCTMCP complexes show weak to zero antiferromagnetic coupling between metal centres and thus no long-range ordering.     

Synthesis and cytotoxicity of dinuclear complexes containing ruthenium(II) bipyridyl units linked by a bis(pyridylimine) ligand

Enantiopure dinuclear ruthenium polypyridyl complexes of the form [Ru(2)(LL)(4)L(1)](PF(6))(4) (LL = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen); L(1)= C(25)H(20)N(4) a bis(pyridylimine) ligand containing a diphenylmethane spacer) have been synthesized using the chiral building blocks cis-[Ru(bpy)(2)(py)(2)](2+) and cis-[Ru(phen)(2)(py)(2)](2+). These dinuclear ruthenium complexes have been characterised using NMR, mass spectrometry, UV-visible absorbance, circular dichroism and linear dichroism. The compounds exhibit good photo and thermal stability. The extinction coefficient for the bpy complex at 478 nm is epsilon(478) = 15,700 mol(-1) cm(-1) dm(3) and for the phen complex is epsilon(478) = 24,900 mol(-1) cm(-1) dm(3). Both complexes have their longest wavelength (metal to ligand charge transfer) transition predominantly x/y (short axis)-polarised while the transitions at shorter wavelength are a mixture of x/y and z-polarisations, similar to both the copper helicate and iron triple helicate studied previously. Cytotoxicity studies reveal that the compounds are dramatically less active against cancer cell lines than the recently reported supramolecular cylinders prepared from the same bis(pyridylimine) ligand.