Suzuki Coupling Reaction Research Articles

The effect of the number of cyanostilbene building blocks on the self-assembly and photophysical property of pyrene-based liquid crystals

The synthesis, self-assembly and physical properties of two series of di/tetra-substituted pyrene-based liquid crystals were reported. These compounds were synthesized by using Suzuki coupling and Knoevenagel reactions as key steps. The effects of the number of cyanostilbene arms connecting to central pyrene on the mesomorphic and emission behaviors with structurally related compounds were investigated. The lower pyrene-based homologue containing two cyanostilbene arms could self-assemble into rectangular columnar phase in which two molecules aggregated into a disc, whereas the higher pyrene-based homologues could self-assemble into hexagonal columnar phase in which four molecules aggregated into a disc. The pyrene-based liquid crystals containing four cyanostilbene arms could also self-assemble into hexagonal columnar phase in which two molecules aggregated into a disc. The self-assembly process and the models for arrangements within these columnar phases were proposed and discussed in detail. These compounds also exhibited distinct slovatochromism and strong fluorescence in both solution and aggregated states. Therefore, controlling molecular structures of functional liquid crystal materials was an efficient way to tune the self-assemblies and emission properties.

Controlling the light-induced structural isomerism of lipophilic azo-bridged porphyrin dimer via steric hindrance modulated functional linkers

Herein, two azo-bridged porphyrin dimers were synthesized via Sonogashira and Suzuki coupling reactions. The relationship between molecular structures and electronic structures was investigated by spectroscopic and electrochemical characterizations. In addition, the light-induced structural isomerism of lipophilic azo-Bridged porphyrin dimer could be controlled via steric hindrance modulated functional linkers, and it can only be succeeded in the case of expanded azo-bridged porphyrin dimer.

Palladium (Pd)-based Photocatalysts for Suzuki Coupling Reactions: An Overview

Abstract: Extensive research has been documented in the last few decades on the utilization of near IR, visible and UV light in organic chemical transformations. In this brief review, we provide an overview of the most noteworthy achievements in the area of photocatalytic Suzuki coupling reactions by palladium (Pd)-based catalytic systems. The works on different types of Pd-based photocatalysts for Suzuki coupling reaction and their characteristic as well as catalytic activity in terms of substrate scope, recyclability, TON or TOF are discussed herein.

Highly effective photoativation Pd catalyst for Suzuki coupling reaction

Suzuki coupling reaction is widely applied for constructing biaryl skeletons in various fields. Designing and developing highly effective catalysts are essential regarding the Suzuki coupling reaction. Here, we report a simple light irradiation approach to achieve the highly efficient Suzuki coupling reaction via the application of low valence Pd homogeneous catalyst. The catalyst exhibited a TOF value of 76,000 h−1. We systematically investigated the impact of various experimental conditions on catalytic performance and further clarify the evolution of Pd species during the light irradiation and catalytic reaction process. This work provides a facile strategy for designing highly effective catalysts for the Suzuki coupling reaction and understanding the detailed evolution process of Pd during the reaction process.

Catalytic activity of the two magnetic nanoparticles-supported palladium catalysts for Suzuki coupling reaction under green conditions

Two palladium Schiff base complexes supported on magnetic nanoparticles, namely, P,N-Pd-Fe3O4 and CPS-MNPs-NNN-Pd, were successfully used as efficient heterogeneous catalysts for the Suzuki coupling reaction under mild and green conditions. We compared the catalytic activity of these two catalysts and the results indicated that the CPS-MNPs-NNN-Pd catalyst promoted the reaction more efficiently due to its structure. Only 0.1 mol% of CPS-MNPs-NNN-Pd catalyst was required to promote the Suzuki reactions and these reactions were performed efficiently for aryl iodides, bromides, and also chlorides. Notably, this catalyst had higher TON and TOF numbers than most of the previously reported catalysts. Moreover, the catalyst could be easily separated from the reaction mixture under the outer or external magnetic field and reused at least for 4 times without appreciable loss of its catalytic activity.

Energy band gap modulation and photoinduced electron transfer fluorescence sensing properties of D–A conjugated polymers containing benzotriazole

AbstractTwo new conjugated polymers containing benzotriazole were synthesized via Suzuki coupling reaction, and the polymer with lower energy band gap was created by designing the structure of the acceptor unit by introducing thiophene unit at both ends of the benzotriazole. Surprisingly, the fluorescence emission of D–A conjugated polymer with modified unit shifted from blue to yellow light, and the polymer had a higher fluorescence quantum efficiency. In addition, thiophen benzimidazole was introduced as the side chain unit for the study of photoinduced electron transfer (PET) mechanism. The addition of Fe3+ and Cu2+ caused significant quenching of fluorescence of polymers, and the polymer with high energy band gap exhibited higher fluorescence quenching ability. Moreover, when exploring the fluorescence sensing of [P‐Fe3+] complex in the presence of anion, it was observed that the PO43− competed with [P‐Fe3+] complex for Fe3+, interrupting the fluorescence sensing mechanism eventually leading to the recovery of fluorescence. The design approach utilized in this survey for D–A conjugated polymer paves the way for a novel mean of functional control of fluorescence sensor based on PET fluorescence sensing.

Benzothiadiazolyl‐pyridine and ‐2,2′‐bipyridine Ligands for Luminescent and Magnetic Complexes

AbstractTwo new luminescent ligands, 4‐(2‐pyridine)‐7‐methyl‐2,1,3‐benzothiadiazole (L1) and 4‐(2,2‐bipyridine)‐7‐methyl‐2,1,3‐benzothiadiazole (L2), based on 2,1,3‐benzothiadiazole and pyridine or bipyridine were obtained by Suzuki coupling reactions. DFT and TD‐DFT type calculations have been performed on L1 and L2 in order to assign their experimental UV‐visible and emission bands. Reaction of L1 and L2 with metal(II) chlorides (M=Zn, Mn, Cu) provided the neutral complexes of formulas [ZnL1Cl2] (1), [Zn(L1)2Cl2] (2), [ZnL2Cl2] (3), [MnL2Cl2] ⋅ 0,5CH2Cl2 (4) and [CuL2Cl2] ⋅ H2O (5) which have been structurally characterized. The Zn(II) ions in 1 and 2 are four‐coordinate in somewhat distorted tetrahedral N2Cl2 surroundings with L1 adopting bidentate (1) and monodentate (2) coordination modes. Complexes 3–5 are isostructural and their metal atoms are five‐coordinate in distorted square pyramidal environments with three nitrogen atoms from the tridentate L2 ligand and a chlorine building the basal plane and another chlorine atom occupying the apical position. The three Zn(II) complexes are strongly luminescent in solution and the solid state, while the cryomagnetic study of the paramagnetic compounds 4 and 5 in the temperature range 2.9–300 K shows a Curie‐Weiss behaviour typical of small antiferromagnetic interactions which are mediated by weak intermolecular contacts.

Synthesis, structures, electrochemical characterizations, theoretical and anticancer studies of Pd(II)-, Pt(II)- NHC complexes

We present the synthesis of two novel cationic Pd(II)- and Pt(II)- complexes ligated to a new C ∩ N donor N-heterocyclic carbene (NHC) ligand 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolin-2-ylidene, (1). Capitalizing 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolium hexafluorophosphate (1.HPF6), two novel isoelectronic and isostructural [Pd(1)2][PF6]2 (2), and [Pt(1)2][PF6]2 (3) complexes were synthesized. All the compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR, UV–Vis, mass spectroscopic studies, and finally single-crystal X-ray studies. X-ray crystallographic studies revealed both complexes 2 and 3 adopted square planar geometry. Electrochemical studies revealed Pt(II)/Pt(IV) reversible redox potential at 0.52 V. The catalytic activity of Pd(II)–NHC complex, 2 was tested for Suzuki coupling reactions. The structural assignments were further supported by DFT calculations. Molecular docking studies show a better binding affinity of 3 with Human-DNA Topoisomerase and BCL-2 protein compared to 2 and the scope of the complex 2 and 3 may be used as a drug. Cytotoxicity studies revealed that Pt(II)–NHC complex 3 is more potent than Pd(II)–NHC complex 2 against the breast cancer cell line (MCF-7) (IC50,7.9 ± 0.84 vs 6.0 ± 0.72 μM).

Fluorinated aldosterone synthase (CYP11B2)-inhibitors for differential diagnosis between bilateral and unilateral conditions of primary aldosteronism

The enzyme aldosterone synthase (CYP11B2) is specifically expressed in aldosterone-producing tissue of the adrenal cortex and is overexpressed in aldosterone-producing adenomas (APA). It therefore represents an ideal target for molecular imaging, particularly for the differential diagnosis between bilateral hyperplasia and unilateral APA in primary aldosteronism. However, the presence of the cortisol-producing enzyme 11β-hydroxylase (CYP11B1) in the adrenal cortex remains very challenging owing to its high homology to CYP11B2. Within this study, we efficiently synthesized a variety of disubstituted fluorinated pyridines and pyrazines by Suzuki coupling reactions. These compounds were evaluated for their ability to inhibit CYP11B1 and CYP11B2 in transfected Y1 cells and in NCI-h295 cells. Several compounds were found to exhibit excellent affinity (IC50 < 10 nM) to CYP11B2 as well as strong selectivity (up to 125-fold) over CYP11B1. These findings support the further development of an analogous 18F-labelled PET tracer.

Silver Natural Asphalt Sulfonate (NA-SO3Ag): Fabrication and Utilization as a New Heterogeneous, Carbonaceous, and Retrievable Nanocatalyst for C(sp2)-X (X = C, S, and Se) Bond Formation.

Silver-based catalysts are valuable catalysts in various areas of the chemical industry, organic syntheses, and transformations, and from a chemical and industrial point of view, their recycling is very important. Herein, silver natural asphalt sulfonate (NA-SO3Ag) was fabricated via the grafting of Ag(I) on the surface of the solid natural asphalt sulfonate as a novel and efficient recoverable sliver nanocatalyst. Natural asphalt is one of the hydrocarbons that are found in mineral veins. The structure of NA-SO3Ag was characterized by diverse microscopic and spectroscopic techniques including Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and inductively coupled plasma optical emission spectroscopy (ICP-OES) techniques. The NA-SO3Ag nanocatalyst was utilized for C-Se and C-S bond formation via coupling reactions of aryl halides and organic disulfides/diselenides to afford a wide variety of diaryl sulfides/selenides in good to excellent yields. Additionally, the utilization of NA-SO3Ag in C-C bond formation was examined in Suzuki coupling reactions successfully. For at least 6 trials, this heterogeneous catalyst can be separated and reused without any activity reduction.

One-Step Synthesis of 7-Bromobenzo[c]chromeno[4,3,2-gh]phenanthridines through a Sequential Bromination/Cyclization/Aromatization Reaction Using N-Bromosuccinimide (NBS).

Herein, metal- and oxidant-free synthesis of 7-bromobenzo[c]chromeno[4,3,2-gh]phenanthridines is reported using N-bromosuccinimide. Sequential regioselective bromination, intramolecular ring cyclization, and aromatization reactions occur in a single step through a successive radical-catalyzed pathway. The mechanistic pathway for the cyclization is supported by a DFT study. Selective bromination in the fully aromatic skeleton is accomplished without involving additional aromatic electrophilic ring bromination. As a synthetic application, the Suzuki coupling reaction of compound 5a with boronic acid is reported to get compound 8a. Aggregation-induced emission of one of the synthesized compounds (5h) is also investigated in THF/hexane solvent along with concentration-dependent emission spectroscopy.

Efficient non-doped sky-blue fluorescent organic light emitting devices based on cyanopyridine-containing anthracene derivatives

Two new cyanopyridine-containing anthracene derivatives with asymmetrical donor-π-acceptor (D-π-A) molecule structure have been successfully synthesized by Suzuki coupling reaction, namely 4-(10-(9-phenyl-9H-carbazol-3-yl)anthracen -9-yl)benzonitrile (3CzAnPyCN) and 4-(10-(4-(9H-carbazol-9-yl)phenyl)anthracen -9-yl)benzonitrile (pCzAnPyCN). The non-doped organic light emitting devices (OLEDs) using 3CzAnPyCN and pCzAnPyCN as emitters simultaneously achieved high efficiency stable sky-blue luminescence, corresponding to the maximum external quantum efficiency (EQE) of 8.07% and 8.13% with the Commission International de L'Eclairage (CIE) coordinates of (0.18, 0.35) and (0.16, 0.24), respectively. In addition, extremely low efficiency roll-offs were also evaluated in this work. The EQE values remained as high as 7.80% and 7.88% at the luminance of 1000 cd/m2, 7.31% and 6.95% at the luminance of 10000 cd/m2 for 3CzAnPyCN and pCzAnPyCN, respectively. It is found, by photophysical experiments and density functional theory analysis, that the excited state property of the luminogens revealed that the “hot excitons” induced reverse intersystem crossing (RISC) played a crucial role in improving efficiency. Such an excellent electroluminescence (EL) performance achieved in these non-doped OLEDs is among the highest values based on sky-blue fluorescent materials, potential for future optical applications.

Synthesis of a Water‐Soluble Pd‐Based Catalyst with a Thymine‐Modified β‐Cyclodextrin Ligand for Suzuki Coupling Reactions

AbstractHerein, the synthesis and crystal structure identification of thymine‐modified β‐cyclodextrin (mono‐(6‐Thymine‐6‐deoxy)‐β‐CD, Thy‐CD) are reported. The catalyst system (Pd@Thy‐CD) was prepared by using the thymine‐modified β‐cyclodextrin as ligand and palladium acetate (Pd(OAc)2) as palladium source. The as‐obtained Pd@Thy‐CD catalyst was characterized by NMR, IR, SEM, and XPS analysis. The catalyst can efficiently catalyze the aqueous phase Suzuki coupling reaction in situ. Under mild reaction conditions, the catalyst system provides excellent yields for the Suzuki coupling reaction of aryl halides, including with aryl chlorides and aryl boronic acids in water. The major advantages of this technique are the ease of preparation of the palladium catalyst, the aqueous phase coupling reaction, the broad functional group tolerance, and the easy recyclability.

Double-bounded diphenyl-contained fluorene polymers for Sc-SWCNTs composite to ammonia gas sensors: Diphenylethene or diphenylmethanimine

Semiconductor-type carbon nanotubes, renowned for their exceptional optoelectronic properties, are considered as the most promising candidates to replace conventional silicon-based semiconductors. However, the obtaining high purity of semiconductor-type single-walled carbon nanotubes (sc-SWCNTs) is a challenging task. In this study, the Suzuki coupling reaction was employed to synthesize two structurally similar alternating copolymers, which effectively separated the sc-SWCNTs from commercially plasma single-walled carbon nanotubes. As result, the copolymers exhibited outstanding selectivity for sc-SWCNTs with 99.9% of purity. Generation of a complex film at the surface. Employing these polymer/sc-SWCNTs composite materials, the ammonia gas sensing devices were fabricated. The results showed that both devices demonstrated rapid and exceptional response towards ammonia gas vapor. Test results revealed that when the ammonia gas vapor concentration of 20 ppm, the two polymer/sc-SWCNTs-based sensors exhibited response values of 5.0% and 3.3%, respectively, and the calculated limits of detection (LOD) of the sensors were 64.5 ppb and 53.5 ppb. These sensors demonstrated significant advantages in response and selectivity towards ammonia gas vapor compared to previous studies.

The Influence of Positional Isomerism of Terminal Alkyl Chains on Mesomorphic and Photophysical Behavior of Unsymmetric α-cyanostilbene-based Tetracatenars.

Two series of unsymmetric α-cyanostilbene-based tetracatenars containing three hexadecyl chains at one end and one alkyl chain with varying lengths at the other end were prepared by using Suzuki coupling and Knoevenagel reactions. These tetracatenars with the terminal three hexadecyl chains, which are adjacent to the cyano group are non-mesogens, whereas the isomers with one alkyl chain, which is adjacent to the cyano group display transition from non-mesogens to monotropic hexagonal columnar liquid crystal upon elongation of the alkyl chain. This transition could be attributed to that the three hexadecyl chains which are adjacent to the cyano group decrease the interactions between π-conjugated rigid cores, hindering the formation of mesophase. In addition, weak slovatochromism implies weak ICT in both series tetracatenars. Both series isomers exhibit distinct AIE characteristics attributing to the presence of α-cyanostilbene, which could induce stereoisomerism and restricted intermolecular rotation in the aggregated state. Different mechanochromism behaviors could be achieved due to the positional isomerism of terminal alkyl chains. Therefore, tuning the position of terminal alkyl chains could give rise to distinct changes in the molecular aggregate, which provides a scheme to build multifunctional materials with diverse potentials.

High-efficiency PdNi single-atom alloy catalyst toward cross-coupling reaction

The preparation of Pd-based catalysts with rich electrons and a high atom dispersion rate is of great significance for improving the reactivity of cross-coupling reactions, which is a powerful tool for pharmaceutical and fine chemical synthesis. Here, we report a PdNi single-atom alloy (SAA) catalyst in which isolated Pd single atoms are anchored onto the surface of Ni nanoparticles (NPs) applied for Suzuki coupling reactions and Heck coupling reactions. The 0.1% PdNi SAA exhibits extraordinary catalytic activity (reaction rate: 17,032.25 mmol h−1 gPd−1) toward the Suzuki cross-coupling reaction between 4-bromoanisole and phenylboronic acid at 80 °C for 1 h. The excellent activity is supposed to attribute to the 100 percent utilization rate of Pd atoms and the highly stable surface zero-valance Pd atoms, which provides abundant sites and electrons for the adsorption and fracture of the C-X (X = Cl, Br, I) bond. Moreover, our work demonstrates the excellent application prospect of SAAs for cross-coupling reactions.

Well-Balanced Ambipolar Charge Transport of Diketopyrrolepyrrole-Based Copolymers: Organic Field-Effect Transistors and High-Voltage Logic Applications.

A poly (3,6-bis(thiophen-2-yl)-2,5-bis(2-decyltetradecyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione-co-(2,3-bis(phenyl)acrylonitrile)) (PDPADPP) copolymer, composed of diketopyrrolopyrrole (DPP) and a cyano (nitrile) group with a vinylene spacer linking two benzene rings, is synthesized via a palladium-catalyzed Suzuki coupling reaction. The electrical performance of PDPADPP in organic field-effect transistors (OFETs) and circuits is investigated. The OFETs based on PDPADPP exhibit typical ambipolar transport characteristics, with the as-cast OFETs demonstrating low field-effect hole and electron mobility values of 0.016 and 0.004cm2 V-1 s-1 , respectively. However, after thermal annealing at 240°C, the OFETs exhibit improved transport characteristics with highly balanced ambipolar transport, showing average hole and electron mobility values of 0.065 and 0.116cm2 V-1 s-1 , respectively. To verify the application of the PDPADPP OFETs in high-voltage logic circuits, compact modeling using the industry-standard small-signal Berkeley short-channel IGFET model (BSIM) is performed, and the logic application characteristics are evaluated. The circuit simulation results demonstrate excellent logic application performance of the PDPADPP-based ambipolar transistor and illustrate that the device annealed at 240°C exhibits ideal circuit characteristics.

Synthesis of Chiral Tertiary Allylic- and Propargylic Fluorides from Nonaflates of Chiral α-Fluorinated β-Keto Dicarbonyl Compounds.

The acetyl group of chiral α-fluorinated dicarbonyl compounds was transformed to nonaflates through a reaction with perfluorobutanesulfonyl fluoride in the presence of DBU in 82-95% yield. These nonaflates were used in Suzuki and Sonogashira coupling reactions to afford chiral tertiary allylic fluorides bearing gem-disubstituted terminal alkenes with excellent optical purities (45-91%, ≥94% ee). In addition, chiral tertiary propargylic fluorides were obtained from the reaction of nonaflates with DBU (73-86%, ≥94% ee).

Synthesis of lysiformine, a marine-derived 3-hydroxypyridine alkaloid

A synthesis of the bisindole alkaloid lysiformine is reported. The heterocyclic skeleton of the natural product was assembled from a kojic acid-derived pyridine using iterative Suzuki coupling and reductive alkylation reactions. The NMR spectroscopic data of the synthetic sample was in excellent agreement to the natural product, confirming that lysiformine is a rare example of a marine natural product harbouring a 3-hydroxypyridine.

Highly efficient color mixing system for the fine-tuning of white light–PLEDs using blue and red poly-chromophores

The fine tuning of color and white light emission was achieved from the simple blending of two different types of polychromophores. The π-conjugated polymeric chromophores (blue and red) were synthesized and characterized for white light polymer emitting diode (WPLED) applications. The binary luminescent materials, Blue polymeric chromophore (BPy) and (Red polymeric chromophore (RPy), were obtained from the respective monomers via a standard Suzuki coupling reaction. The tuning of colors and white light emission were attained directly mixing of two polymeric chromophores (blue, red) in different ratio. The prepared polymer materials were confirmed using standard tehniques such as, Fourier transform infrared (FT-IR) and 13C and 1H-nuclear magnetic resonance (NMR) spectroscopy, while the gel-permeation chromatography result revealed the polymeric properties of the materials. The polymeric materials surfaces morphologies were analysed throught the FE-SEM and AFM analysis. The TGA (Thermogravymetric analysis) used to study the thermal property of the two prepared polymeric materials. The UV–visible and fluorescence spectrophotometry was applied to examine the optical features of the materials. The BPy and RPy polymers shows absorption peaks at 375 nm and 426 nm, respectively. The obatined emission peaks of BPy and RPy are at 426 nm and 603 nm, respectively. These results show that BPy and RPy belong to the blue and red emissive categories, and the white light emission was obtained with the mixing ratio of BPy(80%)-RPy(20%). The bandgap of these materials was calculated by cyclic voltammetry, and the theoretical bandgap of the materials was calculated by density functional theory analysis. Finely structured devices were fabricated, and the efficiencies of the BPy, RPy, and BPy-RPy were analyzed to assess the luminance productivity of the materials. In summary, this paper proposes a simple method to achieve white color emission by mixing polymeric chromophores at different ratios.