Synthesis and characterization of white-light-emitting polyfluorenes containing orange phosphorescent moieties in the side chain

Two orange phosphorescent iridium complex monomers, 9-hexyl-9-(iridium (III)bis(2-(4'-fluorophenyl)-4-phenylquinoline-N, C-2')(tetradecanedionate-11,13))-2,7-dibromofluorene (Br-PIr) and 9-hexyl-9-(iridium(III)bis(2-(4'-fluorophenyl)-4-methylquinoline-N, C-2')(tetradecanedionate-11,13))-2,7-dibromofluorene (Br-MIr), were successfully synthesized. The Suzuki polycondensation of 2,7-bis(trimethylene boronate)-9,9-dioctylfluorene with 2,7-dibromo-9,9-dioetylfluorene and Br-Plr or Br-MIr afforded two series of copolymers, PIrPFs and MIrPFs, in good yields, in which the concentrations of the phosphorescent moieties were kept small (0.5-3 mol % feed ratio) to realize incomplete energy transfer. The photoluminescence (PL) of the copolymers showed blue- and orange-emission peaks. A white-light-emitting diode with a configuration of indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/PIr05PF (0.5 mol % feed ratio of Br-PIr)/Ca/Al exhibited a luminous efficiency of 4.49 cd/A and a power efficiency of 2.35 lm/W at 6.0 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.46, 0.33). The CIE coordinates were improved to (0.34, 0.33) when copolymer MIr10PF (1.0 mol % feed ratio of Br-MIr) was employed as the white-emissive layer. The strong orange emission in the electroluminescence spectra in comparison with PL for these kinds of polymers was attributed to the additional contribution of charge trapping in the phosphorescent dopants.

Solvent-dependent formation of di- and trinuclear rhodiurn and iridium complexes bridged by N,N '-donor ligands

Reactions of Rh and Ir hydrido complexes. [Rh(H)(2)(PPh3)(2)(solv)(EtOH)]ClO4 (solv = Me2CO, 1a; EtOH, 1b) and [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]BF4 (2), with various N,N'-donor bridging ligands, such as pyrazine (pyz), 4,4'-trimethylenedipyridine (tmdp) and di(4-pyridyl) disulfide (dpds), in some solvents were examined, and their reaction products were characterized by X-ray crystal structure analysis. IR, H-1 NMR and UV-vis spectra. Rh hydrido complexes, la or 1b, formed a dinuclear Rh complex, [Rh-2(PPh3)(2) {(eta(6)-C6H5PPh2}(2)] (ClO4)(2).6CH(2)Cl(2) (3.6CH(2)Cl(2)), in dichloromethane with a reductive elimination of hydrogen. The reactions of 1a or 1b with the pyz ligand in dichloromethane and tetrahydrofuran gave triangular Rh-3 complexes, [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).CH2Cl2 (5.CH2Cl2) and [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).EtOH (5.EtOH), respectively, in contrast to the formation of a dinuclear Rh hydrido complex, [Rh-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)](ClO4)(2).EtOH A-EtOH). in acetone. The reactions of la or 1b with the tmdp ligand in dichloromethane and 3-methyl-2-butanone also afforded dinuclear Rh complexes, [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2) (6) and [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2).4MeCOCHMe(2) (6.4MeCOCHMe(2)), respectively. On the other hand, Ir hydrido complex 2 reacted with pyz and dpds ligands in dichloromethane to afford dinuclear Ir complexes, [Ir-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)]- (BF4)(2).3CH(2)Cl(2) (7.3CH(2)Cl(2)) and [Ir-2(H)(4)(PPh3)(4)(dpds)(2)](BF4)(2).3CH(2)Cl(2).H2O (8.3CH(2)Cl(2).H2O), respectively, without any reductive elimination of hydrogen. Based on structural studies in solution and in the solid state. it was demonstrated that various Rh and Ir complexes were selectively produced depending on the choice of solvents and N,N'-donor bridging ligands.

Red-Emitting Polyfluorenes Grafted with Quinoline-Based Iridium Complex: "Simple Polymeric Chain, Unexpected High Efficiency"

A series of red-light emitting electrophosphorescent polyfluorenes (PFs) with varying content of a quinoline-based iridium complex, (PPQ)(2)Ir(acac) (bis(2,4-diphenylquinolyl-N,C-2') iridium(acetylacetonate)), in the side chain are synthesized by Suzuki polycondensation. Because of the efficient Forster energy transfer from the PF main chain to (PPQ)(2)Ir(acac) and direct charge trapping on the complex, the electroluminescent emission from PF is nearly completely quenched, even though the amount of iridium complex I incorporated into the polymers is as low as 1 mol %. Based on a single-layer device configuration, a luminous efficiency of up to 5.0 cd A(-1) with a luminance of 2000 cd m(-2) and Commission Internationale de L'Eclairage coordinates of (0.63, 0.35) (x, y) is realized, which is far superior to that of previously reported red-light emitting PFs containing benzothiazole- and isoquinoline-based iridium complexes.

Consequences of N,C,N '- and C,N,N '-coordination modes on electronic and photophysical properties of cyclometalated aryl ruthenium(II) complexes

The effects of isoelectronic replacement of a neutral nitrogen donor atom by an anionic carbon atom in terpyridine ruthenium(II) complexes on the electronic and photophysical properties of the resulting N,C,N'- and C,N,N'-cyclometalated aryl ruthenium(II) complexes were investigated. To this end, a series of complexes was prepared either with ligands containing exclusively nitrogen donor atoms, that is, [Ru(R-1-tpy)(R-2-tpy)](2+) (R-1, R-2 = H, CO2Et), or bearing either one N,C,N'- or C,N,N'-cyclometalated ligand and one tpy ligand, that is, [Ru(R-1-(NCN)-C-Lambda-N-Lambda)(R-2-tpy)](+) and [Ru(R-1-(CNN)-N-Lambda-N-Lambda)(R-2-tpy)](+), respectively. Single-crystal X-ray structure determinations showed that cyclometalation does not significantly alter the overall geometry of the complexes but does change the bond lengths around the ruthenium(II) center, especially the nitrogen-to-ruthenium bond length trans to the carbanion. Substitution of either of the ligands with electron-withdrawing ester functionalities fine-tuned the electronic properties and resulted in the presence of an IR probe. Using trends obtained from redox potentials, emission energies, IR spectroelectrochemical responses, and the character of the lowest unoccupied molecular orbitals from DFT studies, it is shown that the first reduction process and luminescence are associated with the ester-substituted C,N,N'-cyclometalated ligand in [Ru(EtO2C-(CNN)-N-Lambda-N-Lambda)(tpy)](+). Cyclometalation in an N,C,N'-bonding motif changed the energetic order of the ruthenium d(zx), d(yz), and d(xy) orbitals. The red-shifted absorption in the N,C,N'-cyclometalated complexes is assigned to MLCT transitions to the tpy ligand. The red shift observed upon introduction of the ester moiety is associated with an increase in intensity of low-energy transitions, rather than a red shift of the main transition. Cyclometalation in the C,N,N'-binding motif also red-shifts the absorption, but the corresponding transition is associated with both ligand types. Luminescence of the cyclometalated complexes is relatively independent of the mode of cyclometalation, obeying the energy gap law within each individual series.

Metal complexes of thiophene 2-thiocarboxamide. Proton and 13C NMR, IR and electronic spectral studies

The complexes of thiophene 2-thiocarboxamide (TTCA) with some metal chlorides and bromides [M = Ni(II), Zn(II), Cd(II), Hg(II) and Cu(I)] are described. Elemental analyses, magnetic susceptibilities and conductance studies, electronic, IR, proton and 13C magnetic resonance spectra are reported. The results suggest exclusive coordination of TTCA through the thiocarbonyl sulfur. The influence of the thiophene ring on the donor properties of the thioamide are discussed.

Preparation, IR and nuclear magnetic resonance studies on the rare-earth perchlorate complexes of 3-methylpyridine-1-oxide

THE COMPLEXES of pyridine-l-oxide and 2- and 4-substituted pyridine-l-oxides have been investigated previously[l]. The complexes of 3-substituted pyfidine-l-oxides, however, have received little attention. The rare-earth complexes of pyridine-Ioxide[l, 2], 4-methylpyridine- l-oxide [1] and 2,6- dimethylpyfidine-l-oxide[3,4] have been reported earlier. The present paper deals with the isolation and characterisation of 3-methylpyridine-l-oxide (3-Picoline-N-oxide, 3-PicNO) complexes with rare-earth perchlorates.

Oxovanadium(IV) complexes of phenanthroline bases: the dipyridophenazine complex as a near-IR photocytotoxic agent

Oxovanadium(IV) complexes [VOCl(B)(2)]Cl (1-3) of phenanthroline bases (B), viz. 1,10-phenanthroline (phen in 1), dipyrido[3,2-d: 2', 3'-f] quinoxaline (dpq in 2) and dipyrido[3,2-a: 2', 3'-c] phenazine (dppz in 3), have been prepared, characterized and their DNA and protein binding, photo-induced DNA and protein cleavage activity andm photocytotoxicity have been studied. Complex 2, structurally characterized by X-ray crystallography, shows the presence of a vanadyl group in VOClN4 coordination geometry. The dpq ligand displays a chelating mode of binding with a N-donor site trans to the oxo-group. The chloride ligand is cis to the oxo-group. The one-electron paramagnetic complexes show a d-d band near 715 nm in 15% DMF-Tris-HCl buffer. The complexes are redox active exhibiting a V(IV)/V(III) redox couple within -0.5 to -0.7 V vs. SCE in 20% DMF-Tris-HCl/0.1 M KCl. The complexes bind to calf thymus (CT) DNA in the order: 3 (dppz) > 2 (dpq) > 1 (phen). The binding data reveal the groove and/or partial intercalative DNA binding nature of the complexes. The complexes show chemical nuclease'' activity in the dark in the presence of 3-mercaptopropionic acid or hydrogen peroxide via a hydroxyl radical pathway. The dpq and dppz complexes are efficient photocleavers of DNA in UV-A light of 365 nm forming reactive singlet oxygen (O-1(2)) and hydroxyl radical ((OH)-O-center dot) species. Complexes 2 and 3 also show DNA cleavage activity in red light (> 750 nm) by an exclusive (OH)-O-center dot pathway. The complexes display a binding propensity to bovine serum albumin (BSA) protein giving K-BSA values in the range of 7.1 x 10(4)-1.8 x 10(5) M-1. The dppz complex 3 shows BSA and lysozyme protein cleavage activity in UV-A light of 365 nm via (OH)-O-center dot pathway. The dppz complex 3 exhibits significant PDT effect in human cervical cancer HeLa cells giving IC50 values of 1.0 mu M and 12.0 mu M in UV-A and visible light, respectively (IC50 = > 100 mu M in the dark).

Photocytotoxicity and near-IR light DNA cleavage activity of oxovanadium(IV) Schiff base complexes having phenanthroline bases

Oxovanadium(IV) complexes VO(L)(B)] (1-3), where H2L is a Schiff base ligand 2-(2-hydroxybenzylideneamino) phenol and B is 1,10-phenanthroline (phen for 1), dipyrido3,2-d:2',3'-f]quinoxaline (dpq for 2) or dipyrido3,2-a:2',3'-c]phenazine (dppz for 3), have been prepared, characterized and their DNA binding property and photo-induced DNA cleavage activity studied. Complex 3 which is structurally characterized by X-ray crystallography shows the presence of an oxovanadium(IV) moiety in a six coordinate VO3N3 coordination geometry. The complexes show a d-d band within 800-850 nm in DMF. The complexes display an oxidative response near 0.7 V versus SCE for V(V)-V(IV) and a reductive response within -1.1 to -1.3 V due to V(IV)-V(III) couple in DMF-0.1 M TBAP. The complexes are avid binders to calf thymus DNA giving binding constant values of 4.2 x 10(4) to 1.2 x 10(5) M (1). The complexes do not show any ``chemical nuclease'' activity in dark. The dpq and dppz complexes are photocleavers of plasmid DNA in UV-A light of 365 nm via O-1(2) pathway and in near-IR light (752.5 to 799.3 nm IR optics) by HO* pathway. Complex 3 exhibits significant photocytotoxicity in visible light in HeLa cells giving IC50 value of 13 mu M, while it is less toxic in dark (IC50 = 97 mu M). (C) 2010 Elsevier B.V. All rights reserved.

1, 2-Bis (diphenylphosphino) etane bridged dinuclear copper (I) complexes: Investigations of solid state and solution structures by CP/MAS31P NMR spectroscopy, X-ray crystallography, IR spectroscopy and solution 31P NMR and 63Cu NMR spectroscopy

Three different complexes of copper (I) with bridging 1, 2-bis(diphenylphosphino)ethane (dppe), namely [Cu2 (mu-dppe) (CH3CN)6] (ClO4)2 (1), [Cu2 (mu-dppe)2 (CH3 CN)2] (ClO4)2 (2), and [Cu2 (mu-dppe) (dppe)2 (CH3CN)2] (ClO4)2 (3) have been prepared. The structure of [Cu2 (mu-dppe) (dPPe)2 (CH3CH)2] (ClO4)2 has been determined by X-ray crystallography. It crystallizes in the space group PT with a=12.984(6) angstrom, b=13.180(6) angstrom, c=14.001(3) angstrom, alpha=105.23(3), beta=105.60(2), gamma=112.53 (4), V=1944 (3) angstrom3, and Z=1. The structure was refined by least-squares method with R=0.0365; R(w)=0.0451 for 6321 reflections with F0 greater-than-or-equal-to 3 sigma (F0). The CP/MAS P-31 and IR spectra of the complexes have been analysed in the light of available crystallographic data. IR spectroscopy is particularly helpful in identifying the presence of chelating dppe. P-31 chemical shifts observed in solid state are very different from those observed in solution, and change significantly with slight changes in structure. In solution, complex 1 remains undissociated but complexes 2 and 3 undergo extensive dissociation. With a combination of room temperature H-1, Cu-63, and variable temperature P-31 NMR spectra, it is possible to understand the various processes occurring in solution.

Schiff base oxovanadium(IV) complexes of phenanthroline bases showing DNA photocleavage activity at near-IR light and photocytotoxicity

Oxovanadium(IV) complexes VO(L)(B)](ClO4) (1-3) of N-2-pyridylmethylidine-2-hydroxyphenylamine (HL) Schiff base and phenanthroline bases (B), viz. 1,10-phenanthroline (phen in 1), dipyrido3,2-d: 2',3'-f] quinoxaline (dpq in 2) or dipyrido3,2-a: 2',3'-c] phenazine (dppz in 3), were prepared, characterized and their DNA binding property, photo-induced DNA cleavage activity and photocytotoxicity in HeLa cells studied. The crystal structure of 1 shows the presence of a VO2+ moiety in VO2N4 coordination geometry. The complexes show a d-d band at similar to 830 nm in DMF. The complexes display an oxidative V(V)-V(IV) response near 0.5 V versus SCE and a reductive V(IV)/V(III) response near -0.65 V in DMF -0.1 M TBAP. The complexes that are avid binders to CT DNA giving K-b values within 7.1 x 10(4) to 3.2 x 10(5) M-1, do not show any significant chemical nuclease activity in presence of 3-mercaptopropionic acid or glutathione. The dpq and dppz complexes are photocleavers of pUC19 DNA in UV-A light of 365 nm forming both O-1(2) and (OH)-O-center dot radicals and in near-IR light of 785 nm forming (OH)-O-center dot radicals. The dppz complex exhibits photocytotoxicity in visible light in HeLa cells (IC50 = 6.8 mu M). Flow-cytometric study on this complex shows a high sub-G1 phase in light compared to dark indicating PDT effect. (C) 2011 Elsevier B. V. All rights reserved.

Cyclometalated complexes derived from calix[4] arene bisphosphites and their catalytic applications in cross-coupling reactions

Palladium and platinum dichloride complexes of a series of symmetrically and unsymmetrically substituted 25,26;27,28-dibridged p-tert-butyl-calix[4]arene bisphosphites in which two proximal phenolic oxygen atoms of p-tert-butyl-or p-H-calix[4]arene are connected to a P(OR) ( R = substituted phenyl) moiety have been synthesized. The palladium dichloride complexes of calix[4]arene bisphosphites bearing sterically bulky aryl substituents undergo cyclometalation by C-C or C-H bond scission. An example of cycloplatinated complex is also reported. The complexes have been characterized by NMR spectroscopic and single crystal X-ray diffraction studies. During crystallization of the palladium dichloride complex of a symmetrically substituted calix[4]arene bisphosphite in dichloromethane, insertion of oxygen occurs into the Pd-P bond to give a P,O-coordinated palladium dichloride complex. The calix[4]arene framework in these bisphosphites and their metal complexes adopt distorted cone conformation; the cone conformation is more flattened in the metal complexes than in the free calix[4]arene bisphosphites. Some of these cyclometalated complexes proved to be active catalysts for Heck and Suzuki C-C cross-coupling reactions but, on an average, the yields are only modest. (C) 2011 Elsevier B.V. All rights reserved.

Ferrocene-Conjugated Oxidovanadium(IV) Complexes as Potent Near-IR Light Photocytotoxic Agents

Ferrocene-conjugated oxidovanadium(IV) complexes [VO(Fc-tpy)(B)](ClO4)(2) (1-4) and [VO(Ph-tpy)(dppz)](ClO4)(2) (5) as a control [Fc = (eta(5)-C5H4)Fe-II(eta(5)-C5H5), Fc-tpy = 4'-ferrocenyl-2,2':6',2 `'-terpyridine, Ph-tpy = 4'-phenyl-2,2':6',2 `'-terpyridine, B = heterocyclic base: 2,2'-bipyridine (bpy in 1), 1,10-phenanthroline (phen in 2), dipyridoquinoxaline (dpq in 3), dipyridophenazine (dppz in 4)] were prepared and their DNA binding, DNA photocleavage activity and photocytotoxicity studied. The crystal structure of [VO(Fc-tpy)(bpy)](PF6)(2)center dot 3Me(2)CO shows a vanadyl group in six-coordinate (VON5)-O-IV coordination geometry, in which Fc-tpy and bpy display tridentate meridional and bidentate N-donor axial-equatorial binding modes, respectively. The one-electron paramagnetic complexes exhibit a charge-transfer band near 590 nm in DMF. The V-IV/V-III redox couple in 1-4 appears near -0.7 V, whereas the Fc moiety shows a response near 0.6 V vs. SCE in DMF/0.1 M TBAP. The complexes are good binders to calf thymus DNA with K-b values of 10(4)-10(6) M-1. DNA melting and viscometric data suggest groove and/or partial intercalative DNA binding of the complexes. Complexes 3-5 display DNA photocleavage activity in nearIR light of 785 nm. Complex 4 shows significant photocytotoxicity in visible light (400-700 nm) in HeLa cells with low dark toxicity.

Photocytotoxic Oxidovanadium(IV) Complexes of Polypyridyl Ligands Showing DNA-Cleavage Activity in Near-IR Light

Oxidovanadium(IV) complexes VO(pyphen)(L)]Cl2 (1, 2) and VO(pydppz)(L)]Cl2 (3, 4), where L is 1,10-phenanthroline (phen in 1 and 3) and dipyrido3,2-a:2',3'-c]phenazine (dppz in 2 and 4) are prepared and characterized. The crystal structure of VO(pyphen)(phen)](ClO4)2 (1a) shows a six-coordinate VN5O geometry with a VO2+ moiety in which the polypyridyl ligand binds in a meridional fashion and the phen ligand displays a chelating binding mode with an N-donor site trans to the oxidovanadyl group. The complexes show a dd band within 720-750 nm in DMF. The one-electron paramagnetic complexes are 1:2 electrolytes in DMF. The complexes exhibit an irreversible VIV/VIII redox response near -0.85 V vs. SCE in DMF/0.1 M TBAP. The complexes bind to calf thymus (ct) DNA giving Kb values within 7.5 x 104 to 1.1 x 106 M1. The complexes show poor chemical nuclease activity in the dark and exhibit significant DNA-photocleaving activity in near-IR light of 705 and 785 nm forming .OH radicals. Complexes 2-4 show remarkable photocytotoxicity in HeLa cancer cells. FACS analysis of the HeLa cells treated with complex 4 shows cell death as highlighted by the sub G1 peak. Propidium iodide staining data indicate apoptosis as the primary mode of cell death.

Red-light-emitting iridium complexes with hole-transporting 9-arylcarbazole moieties for electrophosphorescence efficiency/color purity trade-off optimizationE

The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations