Synthesis,characterization, and photophysics of electroluminescent fluorene/dibenzothiophene- and fluorene/dibenzothiophene-S,S-dioxide-based main-chain copolymers bearing benzimidazole-based iridium complexes as backbones or dopants

A series of electroluminescent copolymers containing fluorene-2,8-disubstituted dibenzothiophene (PFD), fluorene-2,8-disubstituted dibenzothiophene-S,S-dioxide (PFDo) and phosphorescent benzimidazole-based iridium (Ir) complexes in the backbones were synthesized by the Suzuki coupling reaction. The thermal stabilities, HOMO/LUMO levels and triplet energy gap (E_T) values were enhanced with increasing contents of dibenzothiophene (D) or dibenzothiophene-S,S-dioxide (Do) segments in the copolymers. The relative intensities of phosphorescence and fluorescence were affected by the energy transfer and back transfer efficiencies between the polymer backbones and iridium units as evidenced by solid state PL and EL spectra. PLED devices with a configuration of ITO/PEDOT:PSS (50 nm)/metal-free copolymers (P1–P5), Ir-copolymers (P7–P13) and Ir-doped copolymers (P3 doped with Ir-complexes 6 and 8) (60–80 nm)/TPBI (40 nm)/LiF (1 nm)/Al (120 nm) were fabricated, and the electroluminescence (EL) efficiencies depended on the chemical constituents and triplet energies of the copolymers. The space-charge-limited current (SCLC) flow technique was used to measure the charge carrier mobilities of these copolymers, where both hole and electron mobilities were in the following order: the metal-free copolymers (P2, P3 and P5) > Ir-doped copolymers (P3 + 3 or 10 mol% Ir-complex 6) > Ir-copolymers (P7, P8, P12 and P13).     

Synthesis,structure, and catalytic activity of a new chiral NHC–iridium(III) complex

The new chiral NHC–iridium complex 3 has been prepared in CH₃CN from the reaction between [Ir(COD)Cl]₂, NaOAc, KI, and dibenzimidazolium salt 2 which is derived from (S)-2,2′-diamino-6,6′-dimethyl-1,1′-biphenyl. Complex 3 has been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analysis. It has a distorted-octahedral IrC₂N₂IH core structure, and shows good catalytic activity for the asymmetric hydrosilylation of arylmethyl ketones, leading to 1-arylethanol with moderate ee values.     

In situ Cu(II)-containing chiral polymer complex sensor for enantioselective recognition of phenylglycinol

A chiral polymer P1 was synthesized by the polymerization of 2,5-dibutoxy-1,4-di(benzaldehyde)-1,4-diethynylbenzene (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via Schiff's base formation, and the chiral polymer P2 could be obtained by the reduction reaction of P1 with NaBH₄. P2 can serve as a “turn-off” fluorescent sensor toward Cu²⁺ and Ni²⁺. The in situ generated Cu(II)-containing polymer complex of P2 (Cu(II)-P2) can exhibit remarkable “turn-on” fluorescence enhancement response and considerable enantioselectivity toward unmodified phenylglycinol via a ligand displacement mechanism. More importantly, (R,R)-Cu(II)-P2 solution can turn on bright blue fluorescence color change again upon addition of l-phenylglycinol under a commercially available UV lamp, which can be clearly observed by the naked eyes for direct visual discrimination at low concentration. The simple, rapid and sensitive benign process makes this protocol promising for recognition of phenylglycinol enantiomers.     

Heterobimetallic MIr (M=Pt or Pd) dithiolato bridge complexes

New palladium–iridium and platinum–iridium heterobimetallic bridged dithiolato complexes of general formula [(P-P)M(μ-S-S)Ir(COD)]PF₆ (COD=1,5-cyclooctadiene; M=Pt; P-P=(PPh₃)₂ and S-S=EDT (1,2-ethanedithiolato) (1), PDT (1,3-propanedithiolato) (2) and BDT (1,4-buthanedithiolato) (3); M=Pd; P-P=dppb and S-S=EDT (4), P-P=dppp and S-S=EDT (5) have been prepared.     

The synthesis and single-crystal X-ray structure of the first mononuclear iridium carbonyl hydride with two orthometallated phosphite ligands,cis-[IrHCO{P(O-o-tBuC6H3) (O-o-tBuC6H4)2}2]

[Ir(μ-OMe)(COD)]₂ reacts with tris-ortho-tert-butylphenylphosphite in the presence of carbon monoxide to give the first example of a mononuclear iridium carbonyl hydride complex with two orthometallated phosphite ligands cis-[IrHCO{P(O-o-^tBuC₆H₃) (O-o-^tBuC₆H₄)₂}₂]. The complex shows great stability even under high pressures of hydrogen and carbon monoxide.     

Solvothermal synthesis,structure and photoluminescent properties of europium complex based on fluorene derivatives

A novel coordination polymer, {[Eu₂(L)₃(CH₃OH)(H₂O)]·(CH₃OH)(H₂O)}_n (1), has been synthesized by solvothermal reaction of Eu(NO₃)₃·6H₂O and 9,9-diethylfluorene-2,7-dicarboxylic acid in a mixture solution of CH₃OH and H₂O. Single crystal X-ray structural analysis reveals that complex 1 crystallizes in an orthorhombic, space group P2(1)2(1)2(1), holding the unusual (2,3,8)-connected 3D topological network. Thermogravimetric analysis shows remarkable thermal stability of the structural framework of compound 1, the photoluminescence properties are also discussed.     

One-pot synthesis of molecular dumbbell, [AgL(μ-bpy)AgL]2+ (L = S2O2-macrocycle; bpy = 4,4′-bipyridine)

One-pot reaction of S₂O₂-macrocyclic ligand L with AgClO₄ together with 4,4′-bipyridine (bpy) afforded a unique dumbbell-shaped complex 1, [(AgL)₂(μ-bpy)](ClO₄)₂. The macrocyclic dinuclear silver(I) complex 1 was structurally characterized by X-ray crystallography and MALDI-TOF-MS spectrometry. The crystal structure of 1 shows the silver(I) in a distorted square pyramidal environment formed by two sulfur and two oxygen donors from L and one nitrogen donor from bpy. Comparative NMR studies suggest the existence of the complex 1 in solution.     

Synthesis and structure of vaulted trans-Bis[1-(2-phenoxy)-imidazol-2-ylidene-C2,O]platinum(II) complex

trans-Bis[1-(2-phenoxy)-imidazol-2-ylidene-C²,O]platinum(II) complex bearing a dodecamethylene bridge (1) was synthesized and characterized by ¹H, ¹³C NMR, COSY, NOESY, FT-IR, high-resolution mass spectroscopy, and single crystal X-ray diffraction. X-ray and 2D-NMR analyses revealed that complex 1 has a characteristic syn-conformation in both the solid and solution states, where cofacial phenoxy-NHC ligands are folded and fixed under strong restriction by the vaulted structure. A crystal of 1 obtained from EtOH exhibits weak blue phosphorescence under UV excitation at 320 nm.     

Electron-withdrawing groups and strong-field ligands containing iridium(III) complexes and their efficient blue light-emitting

Two new heteroleptic iridium(III) complexes [Ir(4,6-dfppy)₂(PPh₃)L] (4,6-dfppy = 2-(4,6-difluorophenyl)pyridyl, PPh₃ = triphenylphosphine, L = NCS^?, 1; NCO^?, 2) have been synthesized and fully characterized. By introduction of electron-withdrawing groups such as fluorine atoms on the 4- and 6-positions of 2-phenylpyridyl (ppy) and using strong-field ligands for instance PPh₃ and pseudohalogen as ancillary ligands, the HOMO–LUMO electronic energy gaps of 1 and 2 have been increased sufficiently. The photoluminescence (PL) spectra of 1 and 2 in solution show emission maxima at 456 and 458 nm, respectively, corresponding to efficient blue light-emitting. X-ray analyses show that intra- and intermolecular π–π interactions exist in the solid state of 1 and 2. The PL spectra of 1 and 2 in solid state exhibit about 30 nm spectral red shifts compared with those in solution.     

Synthesis,spectroscopic properties and DFT calculations of a novel multipolar azo dye and its zinc(II) complex

The synthesis and photophysical properties of 5-(diethylamino)-4-[(E)-(4-nitrophenyl)diazenyl]-2-(1,3-benzoxazol-2-yl)phenol (AB-HBO) and its zinc complex were examined. The organic molecule acts as a pH sensitive chromophore and as mononegative ligand for zinc(II) ion. Structural features and photophysical properties of AB-HBO were studied. The solvatochromic blue shift, shown by the ligand in its neutral form, is widely enhanced in its deprotonated form. The color solution ranges from red-orange to violet and blue-green as function of the electronic density deformation. Fluorescence spectra were recorded on both ligand and zinc complex solutions. (TD)DFT calculations have been performed to rationalize the absorbance of chromophore and complex.     

New main-chain hyperbranched polymers: Facile synthesis,structural control,and second-order nonlinear optical properties

In this paper, two new series of hyperbranched main-chain polymers, P1–P6, with chromophore moieties as the core were successfully prepared through “A₃+B₂” approach via simple Sonogashira coupling reaction. By changing the bulky size of comonomers, the structure-property relationship has been investigated according to the concept of “suitable isolation group”. The second harmonic generation (SHG) experiments demonstrated that the hyperbranched structure might be very good architecture for the development of NLO materials with high performance. The benzene ring (Bz) could act as suitable isolation groups in these polymers, while the d₃₃ values of the corresponding polymers P1 and P4, were 152.6 and 86.2 pm/V, respectively, much higher than their linear analog polymers bearing the same chromophore moieties. In addition, these hyperbranched main-chain polymers could combine the large nonlinearities of hyperbranched polymers and high stability of main-chain polymers, providing a new solution to solve the “nonlinearity-stability” trade off existing in the main-chain polymers to some degree.     

Characterization of rigid endo- and exo-η3-allyl carbonyl diethyldithiophosphate molybdenum complexes: crystal structure of endo-Mo(η3-allyl)(CO){η2-S2P(OEt)2}(Dppe)

The stereochemical rigid complexes endo-Mo(η³-allyl)(CO){η²-S₂P(OEt)₂}(η²-dppm) (2a) and exo-Mo(η³-allyl)(CO){η²-S₂P(OEt)₂}(η²-dppm) (2b) are accessible by the reaction of complex Mo(η³-allyl)(CO)₂{η²-S₂P(OEt)₂}(CH₃CN) (1) with dppm in refluxing acetonitrile. Treatment of 1 with dppe in the similar reactive conditions of 2 affords the sole complex endo-Mo(η³-allyl)(CO){η²-S₂P(OEt)₂}(η²-dppe) (3). Complex 3 is characterized by X-ray diffraction analysis.     

Intramolecular hydrogen bond controlled coordination of N-thiophosphorylated thiourea 2,6-Me2C6H3NHC(S)NHP(S)(OiPr)2 with Ni(II)

Reaction of O,O′-diisopropylthiophosphoric acid isothiocyanate (iPrO)₂P(S)NCS with 2,6-dimethylaniline 2,6-Me₂C₆H₃NH₂ leads to the new N-thiophosphorylated thiourea 2,6-Me₂C₆H₃NHC(S)NHP(S)(OiPr)₂ (HL). Reaction of the potassium salt of HL with Ni(II) in aqueous EtOH leads to the complex of formula [Ni(L-N,S)₂]. The molecular structures of the thiourea HL and the complex [Ni(L-N,S)₂] were elucidated by single crystal X-ray diffraction analysis, ¹H and ³¹P NMR spectroscopy and microanalysis. In the complex [Ni(L-N,S)₂], the metal center is found to be in a square-planar N₂S₂ environment formed by the CS sulfur atoms and the P–N nitrogen atoms of two deprotonated L ligands. The ligands are in a trans-configuration.     

Complexation-induced distortion of a naphthalene unit symmetrically-substituted by two (N,N,P) ligands

Binuclear complexes [M₂(μ-BPNNNa)] [${\text{BF}}_4^{-}$]₂ (M = Cu^I, 1; M = Ag^I, 2) were prepared by reaction of 1,5-bis [{6-(diphenylphosphanyl)-2-pyridylmethyl}n-propylamino methyl]naphthalene (BPNNNa) with M(CH₃CN)₄ BF₄ in CH₂Cl₂ and were structurally characterized by single crystal X-ray diffraction studies. In complexes 1and 2, BPNNNa acts as a chelating ligand and two dppy (2-(diphenylphosphino) pyridine) units with two metal atoms are linked together in head-to-tail mode to form an eight-membered ring, which exhibits an eclipsed conformation. A significant feature in complexes 1 and 2 is the deformation of the flat naphthalene unit, in which the two aryl moieties make an angle of 10.3° (1) and 7.2° (2), respectively. A weak Ag⋯Ag interaction is present in the complex 2.     

Redox and catalytic properties of new polypyrrole modified electrodes functionalized by [Ru(bpea)(bpy)H2O] complexes; bpea=N,N′-bis(2-pyridylmethyl)ethylamine, bpy=2,2′-bipyridine

New ruthenium(II) complexes containing one or two pyrrole-functionalized polypyridylic ligands have been prepared in order to study their electrochemical behaviour in heterogeneous phase, after anodic polymerization from CH₂Cl₂ solution on an electrode surface. Complexes containing one pyrrole unit have general formula [Ru(bpea-pyr)(bpy)(L)]²⁺ (bpea-pyr=N-[3-bis(2-pyridylmethyl)aminopropyl]pyrrole, bpy=2,2′-bipyridine, L=Cl, complex 3, or L=H₂O, complex 1), whereas compounds having two pyrrole units correspond to [Ru(bpea-pyr)(bpy-pyr)(L)]²⁺ (bpy-pyr=4-methyl-4′-pyrrolylbutyl-2,2′-bipyridine, L=Cl, complex 4, or L=H₂O, complex 2). Upon oxidative polymerization, all complexes form highly stable polypyrrolic films on a graphite disk electrode surface. An electrode modified with complex 2 polypyrrole coating film, C/poly-2, has been tested as heterogeneous catalyst for the oxidation of benzyl alcohol, showing a remarkably high efficiency and notably improving the results obtained with analogous complexes in homogeneous phase.     

Synthesis and X-ray crystal structure of a bis-cyclometalated phosphorescent red-emitting iridium(III) complex

The synthesis of the bis-cyclometalated complex [{Ir(μ-Cl)(ccpz)₂}₂] (1, cppz = 1-chloro-4-(4-chlorophenyl)-phthalazine) from hydrated iridium(III) chloride and the ligand ccpz in refluxing ethoxyethanol is described. Compound 1 was characterized by spectroscopic means and the crystal structure was determined by X-ray crystallography. The absorption and emission spectra exhibit the new compound as a red-emitting phosphorescent complex.     

Cyclometallated iridium(III) complexes with dicyanamide or tricyanomethanide

Reaction of cyclometallated iridium(III) complex Ir(ppy)₂(PPh₃)Cl (2, ppy = 2-phenylpyridine) with dicyanamide or tricyanomethanide gave neutral mononuclear complexes Ir(ppy)₂(PPh₃)N(CN)₂ (3a) or Ir(ppy)₂(PPh₃)C(CN)₃ (3b), and dicyanamide/tricyanomethanide-linked binuclear iridium(III) complexes [{Ir(ppy)₂(PPh₃)}₂N(CN)₂]⁺ (4a) or [{Ir(ppy)₂(PPh₃)}₂C(CN)₃]⁺ (4b). Substitution of coordinated chloride in the precursor 2 with dicyanamide or tricyanomethanide improved significantly the luminescence properties of 3a–4b. Compared with that in the precursor 2 (1.6%), 2.2 to 9.3-fold enhancement of emission quantum yields was detected in 3a–4b.     

Catalytic hydroboration of vinylarenes using a zwitterionic arylspiroboronate ester iridium complex

Addition of B₂cat₃ (cat = 1,2-O₂C₆H₄) to Ir(acac)(dppb) (1; where dppb = 1,4-bis(diphenylphosphino)butane) gave the novel arylspiroboronate ester iridium complex Ir(η⁶-catBcat)(dppb) (2), the first example of an iridium compound containing a coordinating [Bcat₂]^? anion. Complex 2 is a remarkably selective catalyst precursor for the hydroboration of unhindered vinylarenes using pinacolborane.     

Synthesis and characterization of iron(II) and iron(III) complexes with a tridentate O,N,O′-ligand

The coordination chemistry of the ligand precursor 1-benzoyl-4,5-dihydro-3,5-bis(trifluoromethyl)-1H-pyrazol-5-ol (1a) to iron(II) acetate was studied. In dependence of the added co-ligand different complex geometries were observed. In case of 4-dimethylaminopyridine (DMAP) as co-ligand an octahedral iron(II) complex was found with an O,N,O′-coordination of the tridentate ligand (1a-2H), in which the ligand is planar, the oxygen donors are trans to each other, and the nitrogen donor is in a cis position. The other coordination sites on the iron center are occupied by DMAP ligands. In contrast to that, with triphenylphosphane as the co-ligand an oxidation process took place, which revealed an octahedral iron(III) complex with a comparable geometry for the tridentate ligand (O,N,O′-coordination, 1a-2H) demonstrating the usefulness of 1a-2H to stabilize different oxidation states. The additional coordination sites are occupied by one triphenylphosphane oxide and ethoxide ligands. Interestingly, the ethoxide ligands act as bridging ligands to form a bimetallic complex.