Synthesis of Terpolymers by Click Reactions

Construction of Stable Metal-Organic Framework Platforms Embedding N-Heterocyclic Carbene Metal Complexes for Selective Catalysis

We report a bottom-up approach to immobilize catalysts into MOFs, including copper halides and gold chloride in a predictable manner. Interestingly, the structures of MOFs bearing NHC metal complexes maintained a similar 4-fold interpenetrated cube. They exhibited exceptionally high porosity despite the interpenetrated structure and showed good stability in various solvents. Moreover, these MOFs possess high size activity depending on the size of the substrates in various reactions, compared to homogeneous catalysis. Also, the high catalytic activity of MOFs can be preserved 4 times without significant loss of crystallinity. Incorporation of the various metal complexes into MOFs allows for the preparation of functional MOFs for practical applications.

One-Pot Synthesis of Polypyrazoles by Click Reactions

We developed an efficient one-pot metal-free click polymerization procedure for the synthesis of 3,5-disubstituted polypyrazoles with high yields, high molecular weights, and narrow molecular weight distribution. The method involved two click reactions in a one-pot synthesis. The first reaction was the carbonyl chemistry of “non-aldol” type (condensation reaction of aldehydes with p-toluenesulfonylhydrazide), and the second was a click polymerization reaction of diazo compounds with alkynes. The reactions occurred sequentially by adding the reactants step by step. The diazo compound needed for the second click reaction was generated in situ by the first click reaction. The structures of the polypyrazoles were characterized by IR and ¹H NMR analyses. And their thermal properties and solubility were also tested.

Photocatalytic copper-catalyzed azide–alkyne cycloaddition click reaction with Cu(ii) coordination polymer

Cu(ii) coordination polymers as photocatalysts for the copper-catalyzed azide–alkyne cycloaddition click reaction under household light irradiation in air.

Synthesis and properties of couplable ABCDE star copolymers by orthogonal CuAAC and Diels–Alder click reactions

Well-defined ABCDE star quintopolymers generated by a modular and orthogonal strategy could self-assemble into intriguing nanoobjects sensitive to thermal and pH stimuli.

When CuAAC 'Click Chemistry' goes heterogeneous

Within the green chemistry context, heterogeneous catalysis is more and more applied to organic synthesis. The well known ‘click chemistry’ and especially its flagship, the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC), is now catch up by such heterogenisation process and copper ions or metals have been grafted or deposited on or into various solids, such as (bio)polymers, charcoal, silica, zeolites, POM or MOF.

Synthesis of Miktoarm Branched Conjugated Copolymers by ROMPing In and Out

Architecture represents an underutilized yet promising control element in polymer design due to the challenging synthesis of compositionally varied branched copolymers. We report the one-pot synthesis of miktoarm branched polymers by ring-opening metathesis polymerization. In this work, we graft to and from telechelic poly(3-hexylthiophene), which is end-capped by oxime click chemistry, using various norbornene monomers. The self-assembly of the resulting miktoarm H-shaped conjugated polymers is studied in solution and in the solid state. A dual stimuli-responsive miktoarm polymer is prepared which displays pH-switchable lower critical solution temperature and fluorescence.

Silanized aryl layers through thiol-yne photo-click reaction

Nanometer-scale multilayered coatings were prepared by sequential surface reactions on gold plates. First 4-ethynylphenyl organic layer was electrografted from the parent diazonium tetrafluoroborate salt providing reactive alkynylated gold plate (Au-Y). The latter served for clicking mercaptosilane via a thiol-yne photo-triggered reaction to obtain alkoxysilane-functionalized surface. The trialkoxysilane top groups in turn served as anchor sites for the final sol-gel coating resulting from the surface reaction between aminopropylsilane and tetraethoxysilane (TEOS). It is demonstrated that two coupling agents, namely, aryl diazonium salt and silane, can be coupled using photo-triggered thiol-yne click reaction, resulting in robust multilayered coatings. In addition, the process is versatile in that it offers the possibility to design patterned surfaces. The top sol-gel layer can in turn be reacted with aminosilane, therefore providing a reactive and functional surface that can be used for different applications given the reactivity of amine groups. This approach opens new avenues for photo-triggered click reactions of aryl layers from diazonium salts. It shows that the new class of surface modifiers and coupling agents has much to offer and continues to be renewed for achieving tightly bound, reactive top coatings.

Poly(ethylene oxide) (PEO)-based ABC triblock terpolymers – synthetic complexity vs. application benefits

This review presents a short summary of possible synthetic routes for the synthesis of poly(ethylene oxide) (PEO) containing triblock terpolymers, as well as different applications in the bulk or in solution – including the preparation of porous materials, hybrid systems, and carriers for controlled drug delivery.

Facile Preparation of Supramolecular H-Shaped (Ter)polymers via Multiple Hydrogen Bonding

A well-defined Hamilton wedge (HW) midchain functionalized block copolymer, i.e., polyethylene glycol-b-polystyrene (PEG-HW-PS, M_n,GPC = 5600 Da, PDI = 1.03), was successfully synthesized via a combination of atom transfer radical polymerization (ATRP) and copper-catalyzed azide alkyne cycloaddition (CuAAC). An α,ω-cyanuric acid (CA) difunctional linear homopolymer poly(n-butylacrylate) (CA-PnBA-CA, M_n,GPC = 8100 Da, PDI = 1.09) was concomitantly prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Supramolecular H-shaped macromolecules were-for the first time-prepared through supramolecular self-assembly between HW and CA recognition motifs to generate (PS-b-PEG)·PnBA·(PS-b-PEG) and (PS-b-PS)·PnBA·(PS-b-PS) in CH₂Cl₂ or dichloromethane-d₂ at ambient temperature. The self-assembly process (at a total concentration of the two species of close to 4.5 mM) was evidenced by proton nuclear magnetic resonance (¹H NMR) spectroscopy, diffusion-ordered NMR spectroscopy (DOSY), and dynamic light scattering (DLS) analyses. The results derived via DOSY NMR experiments and DLS combined with a Job plot analysis and in-depth NMR titration experiments indicate that the formation of supramolecular H-shaped macromolecules in 2:1 stoichiometry is efficiently occurring via the employed complementary recognition motifs with high binding constants (between 1.2 and 1.5 × 10⁵ L mol^-1 at ambient temperature).