Palladium-catalyzed Suzuki Coupling Research Articles

Synthesis and photovoltaic properties of the polymers base on thiophene derivatives with electron-deficient 3-nitro-1,2,4-triazole side chains

Three soluble alternating conjugated copolymers PT-TZN, PF-TZN, and PBDT-TZN, composed of thiophene, fluorene, benzo[1,2-b:4,5-b′]dithiophene and thiophene derivatives with 3-nitro-1,2,4-triazole side chains, were synthesized via the palladium-catalyzed Suzuki coupling reaction and Stille coupling reaction. The effects of 3-nitro-1,2,4-triazole on the thermal, photophysical, electrochemical and photovoltaic properties were investigated. The introduction of the 3-nitro-1,2,4-triazole side chains is beneficial for lowering the bandgaps of the polymers. The bulk-heterojunction polymer solar cells were fabricated based on the blend of the as-synthesized polymers and the fullerene acceptor [6, 6]-phenyl-C61-butyric acid methyl ester. The maximum power conversion efficiency (1.13%) was obtained with PBDT-TZN as the electron donor under the illumination of Air Mass 1.5, 100mW/cm2.

Furan-Based Narrow-Band-Gap Copolymers for Red Light-Emitting Diodes and Bulk Heterojunction Photovoltaic Cells

A series of conjugated copolymers (PFO-DFQ) derived from 2,3-dimethyl-5,8-difuran-2-yl-quinoxalines (DFQ) and 9,9-dioctylfluorene (DOF) were prepared by the palladium-catalyzed Suzuki coupling reaction with molar feed ratios of DFQ around 1%, 5%, 15% 30% and 50% respectively. The obtained polymers were readily soluble in common organic solvents. The absorption spectra of the copolymers ranged from 300 nm to 560 nm, with two absorption peaks at around 390 nm and 480 nm, both in solution and thin film. The photoluminescence (PL) emission peaks were in the region from 465 nm to 611 nm in thin solid films. The electroluminescence (EL) emission peaks were from 550 nm to 712 nm, depending on the DFQ content. Bulk heterojunction photovoltaic cells fabricated from composite films of PFO-DFQ copolymers and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as electron donor and electron acceptor respectively, showed power conversion efficiencies 0.13% with open-circuit voltage (Voc) of 0.60V and short-circuit current density (Jsc) of 0.68 mA/cm2 under AM1.5 solar simulator (100 mW/cm2).

Palladium-Catalyzed Decarboxylative Suzuki and Heck Couplings of Azaindole-2-carboxylic Acids: Synthesis of 2-Aryl/Alkenyl-1-phenylsulfonyl-1 H-pyrrolo-[2,3 b]pyridines

A series of 2-aryl-1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridines 3 were obtained by a palladium-catalyzed decarboxylative Suzuki coupling of azaindole-2-carboxylic acid derivative 1. The synthesis of alkenyl-1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridines 9 by a related Heck coupling is also described. Protodecarboxylation operates in the case of azaindole-3-carboxylic acids under the reaction conditions.

Organic photovoltaics based on a crosslinkable PCPDTBT analogue; synthesis, morphological studies, solar cell performance and enhanced lifetime

A thermally crosslinkable poly(cyclopentadithiophene-alt-benzothiadiazole) (PCPDTBT) analogue copolymer with 2-ethylhexyl group and 5-hexenyl group on 4,4-positions of cyclopentadithiophene has been synthesised by palladium catalyzed Suzuki coupling reaction. Space-Charge Limited Current (SCLC) devices show hole mobility of up to 3 × 10−4 cm2 V−1 s−1. In addition, organic photovoltaics (OPVs) were fabricated using fullerene derivatives as acceptor materials. The best performing device exhibited Power Conversion Efficiency (PCE) at 2.0%, which could be improved to 3.7% after inclusion of dithiol additives. Most significantly, the lifetime of the OPV was enhanced by the crosslinking; when light soaked at 1 sun of irradiance, a half-life, t1/2 = 419 hours was measured, which is 51% improvement over an OPV using standard PCPDTBT. This higher stability is accounted for the crosslinkable structure of the polymer after annealing. The crosslinking reaction was confirmed by solubility tests, Fourier transform infrared spectroscopy and morphological analysis conducted by Atomic Force Microscopy and simultaneous synchrotron grazing-incidence small-/wide-angle X-ray scattering.

Synthesis and photovoltaic properties of novel 3,4-ethylenedithiathiophene-based copolymers for organic solar cells

Two novel conjugated polymers based on 3,4-ethylenedithiathiophene (EDTT) were designed and synthesized through the palladium-catalyzed Suzuki coupling method and Stille cross-coupling reactions. Conventional and inverted cells were fabricated and device processing conditions were optimized, respectively. The maximum power conversion efficiency (PCE) of 2.4% was obtained with an open-circuit voltage (Voc) of 0.69 V, a short circuit current (Jsc) of 6.62 mA cm−2, and a fill factor (FF) of 53%, respectively.

Synthesis of a terpolymer containing fluorene, side chain conjugated thiophene and benzothiadiazole and its applications in photovoltaic devices

AbstractA terpolymer (POTVTh‐8FO‐DBT) containing fluorene, side chain conjugated thiophene and 4,7‐dithieny‐2,1,3‐benzothiadiazole was synthesized by palladium‐catalyzed Suzuki coupling method. The polymer is soluble in common organic solvents. The thermal, absorption, and electrochemical properties of the polymer were examined. Photovoltaic properties of POTVTh‐8FO‐DBT were studied by fabricating the polymer solar cells (PSCs) based on POTVTh‐8FO‐DBT as donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as acceptor. With the weight ratio of POTVTh‐8FO‐DBT : PC61BM of 1 : 1 and the active layer thickness of 80 nm, the power conversion efficiency (PCE) of the device reached 0.47% with Voc = 0.61 V, Jsc = 1.61 mA/cm2, and filled factor (FF) = 0.49 under the illumination of AM 1.5, 100 mW/cm2. The results indicated that this polymer was promising donor candidates in the application of PSCs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

2,2′:3′,2′′‐Terthiophene‐Based all‐Thiophene Dendrons and Dendrimers: Synthesis, Structural Characterization, and Properties

The synthesis of generational dendritic oligothiophenes (DOTs) has been successfully achieved by a divergent/convergent approach that involves halogenation, boronation, and palladium-catalyzed Suzuki coupling reactions. The key point in the presented synthetic approach is the use of trimethylsilyl (TMS) protecting groups, which allow for the core-lithiation and subsequent boronation of the dendrons and for the peripheral ipso-substitution with iodine monochloride or N-bromosuccimide. In addition, the TMS protecting groups can be completely removed by using tetrabutylammonium fluoride, thus yielding only-thiophene-based dendrons and dendrimers. Due to their highly branched structure, all these synthesized DOTs are soluble in organic solvents. Chemical structures were confirmed by NMR spectroscopic, mass spectrometric, and elemental analysis. Concentration-dependent (1)H NMR spectroscopic investigations revealed that the higher generation compounds tend to aggregate in solution. Such an aggregation behavior was further confirmed by measuring with MALDI-TOF MS. Both MALDI-TOF MS and gel-permeation chromatography (GPC) analyses confirmed the monodispersity of the DOTs. Furthermore, GPC results revealed that these DOT molecules adopt a condensed globular molecular shape. Their optical and electronic properties were also investigated. The results indicated that these DOTs comprise various conjugated α-oligothiophenes with different chain lengths, which results in the higher generation compounds showing broad and featureless UV/Vis absorption spectra and ill-defined redox waves.

Selenophene and fluorene based narrow band gap copolymers with Eg = 1.41 eV for near infrared polymer light emitting diodes

A series of random low band-gap conjugated copolymers (PFO-DDSTQ) derived from 9,9-dioctylfluorene (DOF) and 6,7-dimethyl-4,9-di(selenophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (DDSTQ) are prepared by the palladium-catalyzed Suzuki coupling reaction. The obtained polymers are readily soluble in common organic solvents. The polymers absorb light from 300 to 880nm with two absorbance peaks at around 370 and 740nm. The optical band gaps of the resulting polymers with 15 or 30% narrow band-gap units in the polymer backbone calculated from the absorption onset are around 1.41eV. The electroluminescent properties of the polymers were investigated and it was found that with 5% DDSTQ copolymerized on the main chain, the resulting polymer PFO-DDSTQ5 exhibited an exclusively near-infrared emission at 860nm.

Purified polar polyfluorene for light-emitting diodes and light-emitting electrochemical cells

Conjugated ployfluorene with 2-(2-(2-methoxyethoxy)ethoxy)ethyl groups (EO-PF) is prepared by the palladium-catalyzed Suzuki coupling reaction. The polymer is purified carefully by a simple chemical procedure. The inductively coupled plasma (ICP) test shows palladium-catalyst in the polymer can be removed by this procedure. The thermal properties, electrochemical properties, UV-Vis absorption properties, photoluminescence properties and electroluminescent properties of the polymer without (EO-PF1) or with purification (EO-PF2) are studied. EO-PF2 shows better PL CIE coordinates in THF solutions as blue light-emitting materials and better photoluminescence stability in thin solid films. Polymer light emitting diodes and electrochemical cells based on EO-PF2 exhibit somewhat improved optoelectronic performance than control devices of EO-PF1.

Combining Gold and Palladium Catalysis: One‐Pot Access to Pentasubstituted Arenes from Furan–Yne and En–Diyne Substrates

A series of furan-yne systems was transformed into the corresponding tetrasubstituted annelated phenol derivatives that bear one bromo group. The two-step procedure consisted of a phenol synthesis and a subsequent electrophilic bromination with N-bromosuccinimide (NBS). The reactions can be performed in a one-pot procedure with the same precatalyst. The halogenation reaction is highly selective only in the presence of the gold catalyst. En-diyne substrates were also suitable starting materials; then the pentasubstituted aromatic core showed a completely different substitution pattern for the phenolic products. Furthermore, a one-pot protocol that consisted of a gold-catalyzed phenol synthesis, a gold-catalyzed halogenation reaction, and a palladium-catalyzed Suzuki coupling was established. The overall efficiency of this procedure was excellent and the substrate scope of the reaction was broad.

P,N-Type benzimidazolyl phosphine ligands for the palladium-catalyzed Suzuki coupling of potassium aryltrifluoroborates and aryl chlorides

This study describes the efficacy of P,N-type benzimidazolyl phosphine ligands, which can be easily synthesized from commercially available and inexpensive starting materials. The application of this ligand array in palladium-catalyzed Suzuki–Miyaura coupling reaction of aryl chlorides with potassium aryltrifluoroborates is described. The air stable benzimidazolyl phosphines in combination with a palladium metal precursor provides highly effective catalysts for the Suzuki–Miyaura coupling of unactivated aryl chlorides and can achieve a catalyst loading of only 0.05mol%.

Fluorescent sensor based on a novel conjugated polyfluorene derivative

A novel water-soluble polyfluorene derivative, poly[(9,9-bis(3′-((N,N-dimethylamino)N-ethylammonium)propyl)-2,7-fluorene)-alt-2,7-(9,9-p-divinylbenzene)]dibromide (P-2) was synthesized by the palladium-catalyzed Suzuki coupling reaction and it’s quaternized ammonium polyelectrolyte derivatives was obtained through a postpolymerization treatment on the terminal amino groups. The electrochemical and optical properties of the copolymers was fully investigated. The results showed that the new polyfluorene derivative had high electronic conductivity and strong fluorescence, therefore it had good potential to be used in chemical and biological sensors, as shown in optical sensing of bovine albumin (BSA) in this study.

Fluorescent oligomers of dibenzothiophene-S,S-dioxide derivatives: the interplay of crystal conformations and photo-physical properties

Fluorescent oligomers where the backbone of dibenzothiophene-S,S-dioxide acts as the acceptor and side chains of aryl methoxy, fluorene, and arylamine act as the donors have been effectively synthesized by the palladium-catalyzed Suzuki coupling reactions, and the photo-physical properties of the compounds were investigated. From the single-crystal XRD patterns the compounds reveal a twisted conformation with an intramolecular structure and show close relationship between intramolecular or intermolecular charge transfer and their photo-physical properties. These patterns provide more comprehensive information, which is unattainable from 1H NMR and 2D-COSY spectra. The emission spectrum in the range of 450–510nm can be finely tuned by systematically altering the position of substitution on the donor units of side chains connected with the backbone acceptor. The fabricated devices displayed a sky blue to deep green in terms of color and performed the CIE (x,y) coordinates with values of (0.18–0.21, 0.25–0.46), respectively.

ChemInform Abstract: Substituted Functional Olefins Through Lateral Sequential Lithiation/Silylation/Condensation of Tertiary Aromatic Amides: A Ligand for Phosphane‐Free Palladium‐Catalyzed Suzuki Coupling Reactions.

An unprecedented lateral sequential lithiation/silylation/condensation of tertiary aromatic amides has been developed that provides an efficient method to build up functional olefins in good yields. In addition, we have established an efficient and simple method that involves UV/Vis, fluorescence, and NMR analyses, to detect the interaction between transition-metal salts and functional olefins containing tertiary amides. This has enabled a highly efficient palladium-catalyzed Suzuki coupling reaction in the presence of tertiary aromatic amide-derived olefin ligands to be developed. The best results were obtained by employing 2 mol-% Pd(OAc)2, 2 equiv. Cs2CO3, a reaction temperature of 80 °C, dioxane as the solvent, and phosphane-free olefin 2d as ligand.

Palladium-catalyzed Suzuki couplings using a novel diaminophosphine oxide as ligand

Abstract A novel diaminophosphine oxide was synthesized and applied as ligand in palladium-catalyzed Suzuki couplings reaction of aryl bromides and chlorides. The coupling reaction proceeded smoothly at mild conditions using 2 mol% Pd2(dba)3 in the presence of tBuOK.

Cross-Linked Core–Shell Nanoparticles Based on Amphiphilic Block Copolymers by RAFT Polymerization and Palladium-Catalyzed Suzuki Coupling Reaction

Well-defined amphiphilic block copolymers, poly[poly(ethylene glycol) methyl ether methacrylate]-block-poly(2,5-dibromo-3-vinylthiophene) poly(PEGMA)-b-poly(DB3VT), were synthesized by reversible addition–fragmentation chain transfer polymerization. A facile bottom-up modification was developed for preparing cross-linked core–shell nanoparticles from the amphiphilic block copolymers, in which an in situ Suzuki coupling reaction was carried out between 2,5-dibromide groups in the block copolymers and various diboronic acid compounds in the presence of a palladium catalyst after micelle formation in THF/H2O solution. The stable and uniform core–shell structure was confirmed by scanning force microscopy and dynamic light scattering observations. Furthermore, the size of the cross-linked core–shell nanoparticles could be controlled by adjusting the compositions of each segment in the block copolymers and Suzuki coupling reaction conditions. The relationship between the optical properties and chemical structur...

Fluorene- and benzimidazole-based blue light-emitting copolymers: Synthesis, photophysical properties, and PLED applications

Blue light-emitting materials are receiving considerable academic and industrial interest due to their potential applications in optoelectronic devices. In this study, blue light-emitting copolymers based on 9,9'-dioctylfluorene and 2,2'-(1,4-phenylene)-bis(benzimidazole) moieties were synthesized through palladium-catalyzed Suzuki coupling reaction. While the copolymer consisting of unsubstituted benzimidazoles (PFBI0) is insoluble in common organic solvents, its counterpart with N-octyl substituted benzimidazoles (PFBI8) enjoys good solubility in toluene, tetrahydrofuran, dichloromethane (DCM), and chloroform. The PFBI8 copolymer shows good thermal stability, whose glass transition temperature and onset decomposition temperature are 103 and 428 degrees C, respectively. Its solutions emit blue light efficiently, with the quantum yield up to 99% in chloroform. The electroluminescence (EL) device of PFBI8 with the configuration of indium-tin oxide/poly(ethylenedioxythiophene):poly( styrene sulfonic acid)/PFBI8/1,3,5-tris(1-phenyl-1H-benzimidazole-2-yl) benzene/LiF/Al emits blue light with the maximum at 448 nm. Such unoptimized polymer light-emitting diode (PLED) exhibits a maximum luminance of 1534 cd/m(2) with the current efficiency and power efficiency of 0.67 cd/A and 0.20 lm/W, respectively. The efficient blue emission and good EL performance make PFBI8 promising for optoelectronic applications. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 2172-2181, 2012

Synthesis of a novel fluorene-based conjugated polymer with pendent bulky caged adamantane moieties and its application in the detection of trace DNT explosives

A novel fluorene-based conjugated polymer with phenylene spacers and steric bulky adamantane moieties in side chains has been synthesized by palladium-catalyzed Suzuki coupling reactions. This design strategy offers several advantages for the detection of trace 2,4-dinitrotoluene (DNT) vapor. The incorporation of the two groups into polymer side chains could retain an effective conjugation length and prevent the π-stacking of polymer chains. The detection of DNT vapor indicated that the polymer displayed higher fluorescence quenching sensitivity toward the explosives in films compared to reference polymers. The fluorescence quenching efficiency of the fluorescent polymer achieved 33.3% in 10s and 71.1% in 60s. The pathways or cavities generated by the two spacers are beneficial for the rapid diffusion of explosive vapor into the film interiors and increase the fluorescence quenching efficiency of the film.

Synthesis, photophysics, and photovoltaic properties of low-band gap conjugated polymers based on thieno[3,4-c]pyrrole-4,6-dione: a combined experimental and computational study

Four novel donor–acceptor (D–A) alternating copolymers were designed and successfully synthesized by the palladium-catalyzed Stille coupling and Suzuki coupling reactions. Utilizing thieno[3,4-c]pyrrole-4,6-dione (TPD) as an acceptor comonomer coupled with dialkoxybithiophene or cyclopentadithiophene as the donor gave polymers PTBT and PTCT. Employing carbazole as the donor and the dithiophene-substituted TPD serving as the acceptor monomers yielded polymers PTC1 and PTC2. Owing to the various strengths of electronic coupling between the donors and the acceptor unit, the band gaps of these polymers can be adjusted from 1.57 to 1.90 eV. Due to the different electron-donor ability of dialkoxybithiophene, cyclopentadithiophene, and carbazole, the HOMO energy levels of polymers were tuned from −5.34 to −5.67 eV, while LUMO levels remained relatively unchanged. The theoretical calculations provided insight to the observed photophysical properties of these polymers. Theoretically estimated band gaps and oxidation potentials correlate well with the experimental data. Carrier mobility and photovoltaic properties of TPD polymers were also investigated for which 1.3% power conversion efficiency was obtained from a blend of PTCT:PC71BM (1:2) bulk-heterojunction device.

Homogenization of inorganic material-supported palladium catalysts in Suzuki coupling reaction at room temperature

Novel and homogeneous zirconium phosphonate-supported Pd catalysts with modest BET surface areas (25.6 and 24.7 m2 g−1), high pore volumes (0.39 and 0.73 cc g−1) and nano-sized pores (1–10 nm) were prepared by embedding Na2PdCl4 particles in an organosoluble, porous and layered zirconium phosphonate with a filiform architecture structure for the first time. In the homogeneous palladium-catalyzed Suzuki coupling reaction at room temperature, various substituted benzene bromides with phenylboronic acids were smoothly converted into corresponding biphenyl compounds (82–97% yields), even in cases of electron–rich derivatives. These supported homogeneous Pd catalysts could be quantitatively recovered by using a solid/liquid separation technique and be highly active without loss of catalytic activity in three consecutive runs.