Suzuki Miyaura Coupling Polymerization Research Articles

Intramolecular Palladium Catalyst Transfer on Benzoheterodiazoles as Acceptor Monomers and Discovery of Catalyst Transfer Inhibitors.

Intramolecular catalyst transfer on benzoheterodiazoles was investigated in Suzuki-Miyaura coupling reactions and polymerization reactions with tBu3PPd precatalyst. In the coupling reactions of dibromobenzotriazole, dibromobenzoxazole, and dibromobenzothiadiazole with pinacol phenylboronate, the product ratios of monosubstituted product to disubstituted product were 0/100, 27/73, and 89/11, respectively, indicating that the Pd catalyst undergoes intramolecular catalyst transfer on dibromobenzotriazole, whereas intermolecular transfer occurs in part in the case of dibromobenzoxazole and is predominant for dibromobenzothiadiazole. The polycondensation of 1.3 equivalents of dibromobenzotriazole with 1.0 equivalent of para- and meta-phenylenediboronates afforded high-molecular-weight polymer and cyclic polymer, respectively. In the case of dibromobenzoxazole, however, para- and meta-phenylenediboronates afforded moderate-molecular-weight polymer with bromine at both ends and cyclic polymer, respectively. In the case of dibromobenzothiadiazole, they afforded low-molecular-weight polymers with bromine at both ends. Addition of benzothiadiazole derivatives interfered with catalyst transfer in the coupling reactions.

Suzuki-Miyaura Coupling Polymerization: Synthesis, Characterization and Optical Properties

The new thiazole-based polymer was synthesized by the Suzuki-Miyaura crossing-coupling reaction of 5-bromo-N-(3-bromophenyl)thiazol-2-amine and 9,9-dioctyl-9H-fluorene-2,7-diboronic acid bis(pinacol) ester. The synthesized monomer and poly[N,N'(1,3-phenylene)bis(thiazol-2-amine)-co9,9’dioctylfluorene] (Poly[Tm]) were characterized by the Elemental analysis, Fourier Transform Infrared spectroscopy, Nuclear Magnetic Resonance spectroscopy, Thermogravimetric analysis and Gel Permission chromatography. Furthermore, the optical properties of the Poly[Tm] were studied at three concentrations of 0.625, 1.25 and 2.5 mM in solution. The absorption band edge values of Poly[Tm] decreased with the increasing concentration of the solutions. When the concentration of the Poly[Tm] solution was increased, transmittance values of the Poly[Tm] were increased, and its molar extinction coefficient was resulted in higher absorbance values. Synthesized Poly[Tm] could provide a novel concept for the design of transistors and photovoltaics.

Ultrastable carbazole-tethered conjugated microporous polymers for high-performance energy storage

Conjugated microporous polymers (CMPs) have considered as organic porous polymers featuring combination of p -conjugated skeletons with permanent micro-porosity. In the present study, we report the synthesis of carbazole-tethered conjugated microporous polymers, BC-Py-CMP and BC-BF-CMP, respectively, through the Suzuki-Miyaura coupling polymerization of the novel 3,3′,6,6′-tetraboronic-pinacolate-9,9′-bicarbazole (BC-4Bpin) with 1,3,6,8-tetrabromopyrene (Py-4Br) and 3,3′,6,6′-tetrabromo-9,9′-bifluorenylidene (BF-4Br). These CMPs exhibited extraordinary thermal stabilities (up to ca. 694 and 569 °C) and high surface areas (up to ca. 1030 m 2 g −1 ). Moreover, the as-prepared BC-BF-CMP exhibited a high specific capacitance of 260 F g −1 at 0.5 A g −1 and showed outstanding cycling stability, having 89.60% capacitance retention of its authentic capacitance over 6000 cycles. The excellent electrochemical capacitances of the BC-BF-CMP were presumably due to the 9,9′-BF could easily accept one electron, causing the reduced form acquiring greater aromaticity by meeting Huckel's requirements, as a result improving the electron transporting properties. Such CMPs tend to have tremendous potential to be used as a high-performance supercapacitors in energy storage systems. • Carbazole-tethered conjugated microporous polymers, CB-Py-CMP and CB-BF-CMP have been prepared. • CMPs exhibited extraordinary thermal stabilities (up to ca. 694 and 569 °C) and high surface areas (up to ca. 1030 m 2 g −1 ). • CB-BF-CMP showed a specific capacitance of 260 F g −1 at a current density of 0.5 A g −1 and an excellent cycling stability.

Synthesis and Optical Properties of Conjugated Copolymers based on Phenoxazine and Fluorene for an Activated Layer in Polymeric Solar Cell Applications

In this research, a conjugated copolymer based on phenoxazine and fluorene units was synthesized via palladium-catalyzed Suzuki–Miyaura coupling polymerization in the presence of a Pd catalyst and K2CO3 as the base. The number-average molecular weight of conjugated polymers was obtained to be approximately 2616 g/mol with a polydispersity index of 1.65. The yield of polymerization was established to be approximately 29%. The chemical structure, average molecular weights and optical properties of the conjugated polymer were characterized via proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR) spectroscopies, gel permeation chromatography (GPC), UV−vis and fluorescence spectroscopies. The conjugated polymer showed an optical band gap of 2.09 eV. The obtained conjugated polymers displayed fluorescence properties under an excitation wavelength of 400 nm. The conjugated polymers exhibit potential as activated layers in organic solar cells, proving the analysis results.

Synthesis of folded H-stacking skipped π polymers consisting of different 2-substituted trimethylene tethering units and their optical and conductive property

A series of polymers P1–P4 ([–CH2CH(Z)CH2–(π conjugated unit)–]n, where Z = a bulky substituent) were synthesized via the Suzuki–Miyaura coupling polymerization and predominantly existed in their folded H-stacking form in the solution and film, which was evidenced by ultraviolet absorption, fluorescent behavior, and X-ray diffraction analysis. The morphology of the polymers in the solid states was dependent on the structure of the Z group present. The conductive nature of P1–P4 was preliminarily demonstrated on hole-only devices. Moreover, a similar onset voltage was observed for P1–P3, which all contained the same π units; however, their current–voltage characteristics were highly dependent on the Z structure. P4, which contained cross-conjugated π units, exhibited a relatively high conductivity with a lower onset requirement.

Precision synthesis of a fluorene-thiophene alternating copolymer by means of the Suzuki–Miyaura catalyst-transfer condensation polymerization: the importance of the position of an alkyl substituent on thiophene of the biaryl monomer to suppress disproportionation

The Suzuki–Miyaura coupling polymerization of PinB-F8T(3)-Br was accompanied by disproportionation, whereas that of PinB-F8T(4)-Br proceeded in a chain-growth polymerization manner to afford a well-defined fluorene-thiophene alternating copolymer.

Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron-Electron Resonance.

Synthetic polymers are mixtures of chains with different lengths, and their chain length and chain conformation are often experimentally characterized by ensemble averages. We demonstrate that double electron-electron resonance (DEER) spectroscopy can reveal the chain length distribution and the chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura coupling polymerization. The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain-terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation, and flexibility can also be accessed within poly(fluorene) nanoparticles.

Synthesis of molecular‐weight‐controlled polyfluorene with boronate at one end

ABSTRACTWe investigated the synthesis of polyfluorene with a pinacol boronate (PinB) moiety at one end and with controlled molecular weight by means of Suzuki–Miyaura coupling polymerization of pinacol (7‐bromo‐9,9‐dioctyl‐9H‐fluoren‐2‐yl)boronate (1) with a palladium(0) precatalyst in the presence of pinacol 4‐trifluoromethylphenylboronate (2) as a chain terminator and CsF/18‐crown‐6 as a base. When we used AmPhos Pd G2, which has a propensity for intramolecular catalyst transfer on a π‐electron face, polyfluorene with the PinB moiety at one end and PhCF3 (derived from 2) at the other end was obtained, and the molecular weight increased in proportion to the feed ratio of [1]0/[catalyst]0, though the molecular weight distribution was broad. Since the molecular weight also linearly increased with respect to the conversion of 1 until the middle stage of polymerization, the polymerization appears to involve chain‐growth polymerization through intramolecular catalyst transfer from the Pd catalyst inserted into the CBr bond of 1. The broad molecular weight distribution might be mainly due to slow initiation and slow termination with 2, rather than polymer–polymer coupling. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2498–2504

Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization of Stilbene Monomer: Different Polymerization Behavior Depending on Halide and Aryl Group of ArPd(tBu3P)X Initiator

ABSTRACTWe report Suzuki–Miyaura coupling polymerization of tetraalkoxy‐substituted 4‐bromostilbene‐4′‐boronic acid 1 with several t‐Bu3P‐ligated Pd initiators; this is the first example of catalyst‐transfer condensation polymerization (CTCP) of a monomer containing a carbon–carbon double bond. When o‐tolylPd(tBu3P)Br was used as the initiator, the o‐tolyl group was not introduced at the polymer end, but polymer with boronic acid at one end and bromine at the other was obtained. However, when we employed stilbenePd(tBu3P)I generated in situ from iodostilbene and Pd(tBu3P)G2 precatalyst, or isolated ArPd(tBu3P)X (Ar, X = Ph, I; o‐tolyl, I; and Ph, Br), the aryl group was introduced at the polymer end, indicating that CTCP of 1 proceeded. Therefore, the iodide and aryl group of the Pd initiator complex is crucial for CTCP of 1. However, the molecular weight distribution of the obtained polymer was broad, possibly because coordination of the carbon–carbon double bond of 1 to ArPd(tBu3P)I resulted in slow initiation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 297–304

Importance of the Balance of Interaction between Palladium Catalyst and Aromatic π-Face for Unstoichiometric Suzuki-Miyaura Coupling Polymerization: Effective Pd cataCXium A Catalyst for Fluorene and Cyclopentadithiophene Monomers

Palladium cataCXium A catalyst was more effective than t-Bu3PPd catalyst for unstoichiometric Suzuki-Miyaura coupling polymerization of excess dibromofluorene with pinacol fluorenediboronate or pin...

Poly(N-alkyl-3,6-carbazole)s via Suzuki–Miyaura Polymerization: From Macrocyclization toward End Functionalization

The metal-catalyzed polymerization of 3,6-carbazoles is explored with emphasis of end-group fidelity of the telechelic polymers. The Suzuki–Miyaura coupling polymerization using asymmetric bifunctional (AB-type) monomers was selected to circumvent the inherent polycondensation character of symmetric (AA/BB-type) monomers. Common synthetic protocols were screened to facilitate the chain growth vs step growth character during the polymerization, e.g., several activation reagents for the boronic ester and various catalytic systems and their associated reaction conditions. The reactions were analyzed in detail by size exclusion chromatography (SEC), 1H NMR spectroscopy, and mass spectrometry including isotope analysis for end-group determination. It was found that the intermediate oligomers are susceptible for macrocycle formation, particularly at low concentration, while longer polymer chains continue to polymerize. The synthetic methodology was extended to utilize functionalized precatalysts and functional terminating agents in order to explore the scope of chain growth vs step growth. The concomitant formation of macrocycles was observed, which indicates the catalyst dissociation and, thus, also the polycondensation pathway. Importantly, the applied low concentration leads to trapping of the undesired nonfunctionalized chains as macrocycles, which can be readily removed from the telechelic linear polymer. In summary, the developed protocols demonstrate the versatility to prepare telechelic poly(3,6-carbazole)s via Suzuki–Miyaura coupling. The azide-decorated poly(carbazole) exemplifies the potential to serve as building blocks for further copper-mediated azide–alkyne cycloaddition reactions.

Synthesis of polyfluorene containing simple functional end group with aryl palladium(II) complexes as initiators

A series of aryl Pd(II) complexes of the formula PdL2(Ar)Br (L = PPh3, 1–8; L = PCy3, 9–11; L = PEt3, 12) and [Pd(P(o-tol)3)(Ar)(μ-Br)]2 (13–18; Ar = substituted phenyl with simple functional group, Cy = cyclohexyl, o-tol = o-tolyl) has been synthesized by direct oxidative addition of Pd(0) precursor and excess aryl bromide. In contrast, the corresponding Pd(II) bromide coordinated with partly aryl-aryl exchanged phosphine was isolated for the bidentate 1,2-bis(diphenylphosphino)ethane (dppe) or 1,3-bis(diphenylphosphino)propane (dppp) ligand, indicating that the aryl-aryl exchange occurs more easily probably because of the chelate effect of the bidentate ligand and the intramolecular π-π interaction between neighboring phenyl rings. Suzuki-Miyaura coupling polymerization of AB-type fluorene monomer with these Pd(II) complexes as initiators was carried out. The aryl Pd(II) complexes with P(o-tol)3 exhibit the catalyst-transfer polymerization at room temperature. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) characterization and end group analysis reveal that the functional group is anchored at the end of polymer backbone. Furthermore, the groups can be transferred to other more useful active groups via simple organic reaction.

Mechanistic Investigation of Catalyst-Transfer Suzuki-Miyaura Condensation Polymerization of Thiophene-Pyridine Biaryl Monomers with the Aid of Model Reactions.

We have investigated the requirements for efficient Pd-catalyzed Suzuki-Miyaura catalyst-transfer condensation polymerization (Pd-CTCP) reactions of 2-alkoxypropyl-6-(5-bromothiophen-2-yl)-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (12) as a donor-acceptor (D-A) biaryl monomer. As model reactions, we first carried out the Suzuki-Miyaura coupling reaction of X-Py-Th-X' (Th=thiophene, Py=pyridine, X, X'=Br or I) 1 with phenylboronic acid ester 2 by using tBu3 PPd0 as the catalyst. Monosubstitution with a phenyl group at Th-I mainly took place in the reaction of Br-Py-Th-I (1 b) with 2, whereas disubstitution selectively occurred in the reaction of I-Py-Th-Br (1 c) with 2, indicating that the Pd catalyst is intramolecularly transferred from acceptor Py to donor Th. Therefore, we synthesized monomer 12 by introduction of a boronate moiety and bromine into Py and Th, respectively. However, examination of the relationship between monomer conversion and the Mn of the obtained polymer, as well as the matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectra, indicated that Suzuki-Miyaura coupling polymerization of 12 with (o-tolyl)tBu3 PPdBr initiator 13 proceeded in a step-growth polymerization manner through intermolecular transfer of the Pd catalyst. To understand the discrepancy between the model reactions and polymerization reaction, Suzuki-Miyaura coupling reactions of 1 c with thiopheneboronic acid ester instead of 2 were carried out. This resulted in a decrease of the disubstitution product. Therefore, step-growth polymerization appears to be due to intermolecular transfer of the Pd catalyst from Th after reductive elimination of the Th-Pd-Py complex formed by transmetalation of polymer Th-Br with (Pin)B-Py-Th-Br monomer 12 (Pin=pinacol). Catalysts with similar stabilization energies of metal-arene η2 -coordination for D and A monomers may be needed for CTCP reactions of biaryl D-A monomers.

Alternating Intramolecular and Intermolecular Catalyst-Transfer Suzuki-Miyaura Condensation Polymerization: Synthesis of Boronate-Terminated π-Conjugated Polymers Using Excess Dibromo Monomers.

The Suzuki-Miyaura coupling polymerization of dibromoarene 1 and arylenediboronic acid (ester) 2 with a Pd catalyst having a high propensity for intramolecular catalyst transfer is reported. The polymerization of excess 1 with 2 affords high-molecular-weight π-conjugated polymer having boronic acid (ester) moieties at both ends, contrary to Flory's principle. This unstoichiometric polycondensation behavior is accounted for by intramolecular transfer of the Pd catalyst on 1. In the polymerization of 1 and 2 having different aryl residues, high-molecular-weight polymer is obtained when the stronger donor aromatic is used as the dibromo monomer and the weaker donor or acceptor aromatic is used as diboronic acid (ester) monomer. The pinacol boronate moieties at both ends of the obtained poly(p-phenylene) (PPP) can be converted to benzoic acid ester, hydroxyl group, and bromine. Furthermore, the reaction of the pinacol boronate-terminated PPP with poly(3-hexylthiophene) (P3HT) having bromine at one end yields a triblock copolymer of P3HT-b-PPP-b-P3HT.

Synthesis of organosoluble and fluorescent aromatic polyketones bearing 1,1′-binaphthyl units through Suzuki–Miyaura coupling polymerization

Nanosized palladium cluster-catalyzed Suzuki–Miyaura coupling polymerization of 1,1′-binaphthyldiyl-bearing diiodides with expanded π-conjugated aromatic diboronic acid pinacol diesters affords aromatic polyketones, which have blue-emitting fluorescent properties (λ em 450–489 nm) in addition to high thermal stability (T g 190–297 °C) and excellent solubility in common organic solvents such as DMSO and NMP.

Investigation of Suzuki–Miyaura catalyst‐transfer polycondensation of AB‐type fluorene monomer using coordination‐saturated aryl Pd(II) halide complexes as initiators

ABSTRACTNovel triarylamine‐based coordination‐saturated aryl Pd(II) halide complexes ligated by PEt3, PCy3, and P(o‐tol)3 were successfully synthesized by direct oxidative addition of aryl halide to the corresponding Pd(0) precursors. Suzuki–Miyaura coupling polymerization of 2‐(7‐halide‐9,9‐dioctylfluoren‐2‐yl)−1,3,2‐dioxaborinane with these Pd(II) complexes as initiators was investigated for the synthesis of poly(fluorene)s with triarylamine end group. Pd(II) complexes with PCy3 or P(o‐tol)3 exhibited catalytic activity and realized the catalyst‐transfer polycondensation at 75 °C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt3 did not proceed, which indicated that the bulky phosphine ligands could facilitate the reductive elimination and further promote the polymerization. In addition, the dimeric Pd(II) complex with P(o‐tol)3 can convert into monomeric Pd(II) intermediate with an open coordination site, which had a higher activity. The end groups of the afforded polyfluorene were analyzed by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry, in which the Ar/H end groups are indicative of the catalyst‐transfer polymerization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1457–1463

Conjugated Star Polymers from Multidirectional Suzuki–Miyaura Polymerization for Live Cell Imaging

Comparative Suzuki–Miyaura coupling polymerization (SMCP) studies with initiators generated in situ from 4-iododiphenylether (1), 4,4′-diiododiphenylether (2), 1,6-bis(4-iodophenoxy)hexane (3) and 1,4-bis(4-iodophenoxy)cyclohexane (4) result in bidirectional growth for 2, versus preferred monodirectional growth for 3 and 4 with their aliphatic spacers, in agreement with a “chain walking” of the metal along the aromatic system. Multidirectional controlled SMCP was initiated on a 1,6,9,14-tetra(4-iodophenoxy)-N,N′-(2,6-diisopropylphenyl) terrylene-3,4:11,12-tetracarboxidiimide (TDI-ArI4) near-infrared fluorescent dye as a tetrafunctional core. MALDI–TOF characterization and end group analysis reveal that four-armed polyfluorene-star-terrylenediimide (PF-star-TDI) polymers are formed with narrow molecular weight distributions (e.g., Mw/Mn = 1.29 at Mn = 1.8 × 104 g mol–1 from GPC). An efficient energy transfer results in a virtually exclusive NIR emission from the core upon excitation of the stars’ polyfluor...

Synthesis of thermally stable, wholly aromatic polyketones with 2,2′-dimethoxy-1,1′-binaphthyl-6,6′-diyl units through nanosized-palladium-cluster-catalyzed Suzuki–Miyaura coupling polymerization

Wholly aromatic polyketones with 2,2′-dimethoxy-1,1′-binaphthyl-6,6′-diyl units in the main chains were synthesized through Suzuki–Miyaura coupling polymerization catalyzed by nanosized palladium clusters, which were easily prepared from Pd(OAc)2, PPh3, K2CO3, and Bu4NOAc in 1,4-dioxane. The resulting polyketones have both high thermal stability (high Tg) and solubility in common organic solvents, such as CHCl3 and N,N-dimethylformamide (DMF). Flexible and pale brown films were obtained by casting from a CHCl3 solution.

A Direct Approach to Organic/Inorganic Semiconductor Hybrid Particles via Functionalized Polyfluorene Ligands

Controlled Suzuki–Miyaura coupling polymerization of 7′‐bromo‐9′,9′‐dioctyl‐fluoren‐2′‐yl‐4,4,5,5‐tetramethyl‐[1,3,2]dioxaborolane initiated by bromo(4‐tert‐butoxycarbonylamino‐phenyl)(tri‐tert‐butylphosphine)palladium (1) or bromo(4‐diethoxyphosphoryl‐phenyl)(tri‐tert‐butylphosphine)palladium (2) yields functionalized polyfluorenes (Mn = 4 × 103 g mol−1, Mw/Mn < 1.2) with a single amine or phosphonic acid, respectively, end‐group. High temperature synthesis of cadmium selenide quantum dots with these functionalized polyfluorenes as stabilizing ligands yields hybrid particles consisting of good quality (e.g. emission full width at half maximum of 30 nm; size distribution σ < 10%) inorganic nanocrystals with polyfluorene attached to the surface, as corroborated by transmission electron microscopy analysis and analytical ultracentrifugation. Sedimentation studies on particle dispersions show that a substantial portion (ca. half) of the phosphonic acid terminated polyfluorene ligands is bound to the inorganic nanocrystals, versus ca. 5% for the amino‐functionalized polyfluorene ligands. Single particle micro‐photoluminescence spectroscopy shows an efficient and complete energy transfer from the polyfluorene layer to the inorganic quantum dot.

Facile synthesis of a variety of triarylamine-based conjugated polymers and tuning of their optoelectronic properties

An alternating copolymer of fluorene and aniline (P1) was prepared by Suzuki–Miyaura coupling polymerization. P1 was used as a precursor for post-functionalization of the aniline moiety by Buchwald–Hartwig amination to give successfully P2–P4, having triarylamine units with a variety of substituents at the para-position of the aromatic ring introduced. The optical properties of P1–P4 were studied by UV–vis and photoluminescence (PL) analyses both in solution and in the film state, showing characteristic absorption and emission behaviors depending on their structures. The electrochemical behavior of the polymers in the thin-film state was also investigated by cyclic voltammetry to exhibit the reversible oxidation/re-reduction couples.