Yne Chemistry Research Articles

Thiol-yne chemistry of diferrocenylacetylene: from synthesis and electrochemistry to theoretical studies.

The thiol-yne coupling chemistry of diferrocenylacetylene (FcCCFc) 1, bearing two electron rich and redox-active ferrocenyl units (Fc = Fe(η5-C5H4)(η5-C5H5)) and an internal triple bond, has been investigated for the first time. In order to determine whether steric limitations might affect hydrothiolation, a model reaction using a functionalized monothiol was tested, namely 2-mercaptoethanol I. The thiol-diferrocenylacetylene reactions were initiated either thermally (in toluene with AIBN) or by UV light irradiation (in THF and in the presence of DMPA as the photoinitiator). The outcomes of these thiol-yne reactions showed a strong dependence on the initiation method used, with the thermally initiated one being the most efficient. These thiol-diferrocenylacetylene reactions mainly afforded the (Z)-stereoisomer of the newly obtained vinyl thioether sulfide FcCHC(Fc)S-(CH2)2OH (2), unlike the more common (E)-vinyl sulfides found in other additions to alkynes. The hydrothiolation of the internal -CC- bond in 1 was successfully extended to dithiol 2,2'-(ethylenedioxy)diethanethiol II, leading to the formation of the (ZZ)-isomer, with four ferrocenyl units, as the major product. According to the electrochemical studies, the new asymmetrical ferrocenyl-vinyl sulfides show iron-iron electronic and electrostatic interactions. Theoretical results for the (Z)-stereoisomer (2) suggest that adiabatic oxidation would lead to the loss of almost one electron on the ferrocenyl subunit closer to the thioether chain. Furthermore, the thiol-yne chemistry of the internal -CC- bond in diferrocenylacetylene has been compared to the external triple bond in ethynylferrocene, the theoretical results of which helped us to rationalize the very different reactivities observed in both metallocenes.

Diselenide–yne chemistry for selenium-containing linear polymer modification

Selenium-containing brush polymers with diverse functional segments were easily prepared through diselenide–yne chemistry.

Hyperbranched poly(ethylenimine-co-oxazoline) by thiol–yne chemistry for non-viral gene delivery: investigating the role of polymer architecture

Synthesis of long-chain hyperbranched poly(ethylenimine-co-oxazoline)s by AB2thiol–yne chemistry is reported, and their application as pDNA transfection agents studied.

Molecularly imprinted polymers by thiol–yne chemistry: making imprinting even easier

Molecularly imprinted polymers (MIPs) are synthetic, bio-mimetic materials with recognition properties on a par with those of antibodies, which feature superior physical and chemical stability.

Thiol–yne chemistry for 3D printing: exploiting an off-stoichiometric route for selective functionalization of 3D objects

An alkyne monomer, bis(propargyl) fumarate, is synthesized and mixed to a thiol monomer to produce DLP-3D printable formulations. Using off-stoichiometric formulations it is possible to print functionalizable objects.

Selective Functionalization with PNA of Silicon Nanowires on Silicon Oxide Substrates.

Silicon nanowire chips can function as sensors for cancer DNA detection, whereby selective functionalization of the Si sensing areas over the surrounding silicon oxide would prevent loss of analyte and thus increase the sensitivity. The thermal hydrosilylation of unsaturated carbon–carbon bonds onto H-terminated Si has been studied here to selectively functionalize the Si nanowires with a monolayer of 1,8-nonadiyne. The silicon oxide areas, however, appeared to be functionalized as well. The selectivity toward the Si–H regions was increased by introducing an extra HF treatment after the 1,8-nonadiyne monolayer formation. This step (partly) removed the monolayer from the silicon oxide regions, whereas the Si–C bonds at the Si areas remained intact. The alkyne headgroups of immobilized 1,8-nonadiyne were functionalized with PNA probes by coupling azido-PNA and thiol-PNA by click chemistry and thiol–yne chemistry, respectively. Although both functionalization routes were successful, hybridization could only be detected on the samples with thiol-PNA. No fluorescence was observed when introducing dye-labeled noncomplementary DNA, which indicates specific DNA hybridization. These results open up the possibilities for creating Si nanowire-based DNA sensors with improved selectivity and sensitivity.

Fabrication of Photoluminescent Quantum Dot Thiol-yne Nanocomposites via Thermal Curing or Photopolymerization.

Strong, flexible, and transparent materials have garnered tremendous interest in recent years as materials and electronics manufacturers pursue devices that are bright, flexible, durable, tailorable, and lightweight. Depending on the starting components, polymers fabricated using thiol–yne chemistry have been shown to be exceptionally strong and/or flexible, while also being amenable to modification by the incorporation of nanoparticles. In the present work, novel ligands were synthesized and used to functionalize quantum dots (QDs) of various diameters. The functionalized QDs were then incorporated into thiol–yne prepolymer matrices. These matrices were subsequently polymerized to form QD thiol–yne nanocomposite polymers. To demonstrate the versatility of the fabrication process, the prepolymers were either thermally cured or photopolymerized. The resulting transparent nanocomposites expressed the size-specific color of the QDs within them when exposed to ultraviolet irradiation, demonstrating that QDs can be incorporated into thiol–yne polymers without significantly altering QD expression. With the inclusion of QDs, thiol–yne nanocomposite polymers are promising candidates for use in numerous applications including as device display materials, optical lens materials, and/or sensor materials.

Well-defined hyperstar copolymers based on a thiol–yne hyperbranched core and a poly(2-oxazoline) shell for biomedical applications

Well defined ‘hyperstar’ copolymers were synthesized by combining hyperbranched polymers produced by thiol–yne chemistry with poly(oxazoline)s.

An efficient approach to synthesize glycerol dendrimers via thiol–yne “click” chemistry and their application in stabilization of gold nanoparticles with X-ray attenuation properties

We report an efficient synthesis of glycerol dendrimers via thiol–yne chemistry for stabilization of AuNPs with X-ray attenuation properties.

Hyperbranched Polymers with High Degrees of Branching and Low Dispersity Values: Pushing the Limits of Thiol–Yne Chemistry

We propose a versatile approach to the production of hyperbranched polymers with high degrees of branching and low dispersity values (Đ), involving slow monomer addition of a thiol/yne monomer to multifunctional core molecules in the presence of photoinitiator and under UV irradiation. The small thiol/yne monomer was synthesized via 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC·HCl) esterification, and batch polymerizations were performed at varying concentrations. The batch thiol–yne polymerizations had fast reaction kinetics and large dispersity values that increased with increasing concentration. Introduction of monomer by slow addition to a multifunctional alkyne core (tri(prop-2-yn-1-yl) 1,3,5-benzenetricarboxylate) or alkene core (triallyl 1,3,5-benzenetricarboxylate) was found to lower dispersity at monomer concentrations of 0.5–2.0 M. Degrees of branching were determined by 1H NMR spectroscopy to be greater than 0.8 in most cases. Increasing the fraction of core molecule was f...

Facile synthesis of a conjugated microporous polymeric monolith via copper-free Sonogashira–Hagihara cross-coupling in water under aerobic conditions

Facile thiol–yne chemistry on a porous polymer monolith: the sulfur donors thus installed effectively take up Ag(i) ions, allowing for the catalysis of heterocyclization reaction in the solid phase.

Synthesis of Polystyrene-Based Hyperbranched Polymers by Thiol–Yne Chemistry: A Detailed Investigation

This contribution reports on the preparation of hyperbranched polymers via thiol–yne photopolymerization of macromolecules bearing a thiol group at one of their chain end and an alkyne moiety at the other. These thiol/yne macromonomers were produced by the reversible addition–fragmentation chain transfer (RAFT) polymerization of styrene mediated by an alkyne-containing chain transfer agent, followed by the aminolysis of the trithiocarbonate groups into thiol moieties. The first part of this report concentrates on studying the effects upon the thiol–yne photopolymerization process caused by the variation of several experimental conditions, such as the size of the thiol/yne macromonomer utilized, the amount of photoinitiator added, or the initial concentration of macromonomer used. Among the various parameters investigated, the latter was demonstrated to be the leading factor that contributes to the final size of the hyperbranched structures. The second part of this article discusses the multidetector size-exclusion chromatography (SEC) analysis of the materials obtained by thiol–yne photopolymerization. This analytical technique allows the molecular weight of the hyperbranched polymers to be determined and the hyperbranched topology to be confirmed, as highlighted by the increased density of the materials compared to that of linear equivalents of the same chemical composition and identical molar masses.

High refractive index polyvinylsulfide materials prepared by selective radical mono-addition thiol–yne chemistry

Linear and hyperbranched polyvinylsulfides with a high refractive index (nD = 1.68–1.76) have been synthesized by selective mono-addition thiol–yne chemistry employing dithiols and di- and trialkynes.

Functionalization of polyurethanes by incorporation of alkyne side-groups to oligodiols and subsequent thiol–yne post-modification

A versatile and upscalable method for the synthesis of polyurethanes (PUs) bearing pendant functionalities at the hard–soft segment interface from easily accessible commercial oligodiols is described. Reactive alkyne groups were introduced to polytetrahydrofuran (PTHF), poly(ε-caprolactone) (PCL) and polydimethylsiloxane (PDMS) diols by cationic ring-opening polymerization of glycidyl propargyl ether using these oligodiols as macroinitiators. The resulting oligodiols, with alkyne side groups located at both chain ends, were subsequently reacted with 1,4-butanediol and hexamethylene diisocyanate for the synthesis of PUs, containing several pendant alkyne groups between the soft and hard segments. The functionalized PUs based on different soft segments (PTHF, PCL or PDMS) have been further modified via metal-free thiol–yne chemistry. Proper reaction conditions were found for quantitative radical thiol–yne coupling reactions with benzyl mercaptan and thioglycerol.

A Facile Route to Functional Hyperbranched Polymers by Combining Reversible Addition-Fragmentation Chain Transfer Polymerization, Thiol-Yne Chemistry, and Postpolymerization Modification Strategies.

This contribution reports on the preparation of functional hyperbranched polystyrene-based materials via a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization, thiol-yne chemistry, and postpolymerization modification reactions. The thiol-yne approach allows the rapid preparation of hyperbranched polymers under mild reaction conditions from polymeric chains bearing a thiol group at one chain end and an alkyne moiety at the other. Postpolymerization modifications of the focal thiol and peripheral alkyne functionalities present within the hyperbranched structures were conducted using two highly efficient strategies, i.e., phosphine-catalyzed thiol-ene reaction and copper-catalyzed azide-alkyne cycloaddition (CuAAC), respectively. In addition to introducing functionalities by postpolymerization modification onto the periphery of the hyperbranched polymers, the interior of the globular structure could also be functionalized by taking advantage of the isocyanate chemical handle of a poly(styrene-co-3-isopropenyl-α,α-dimethylbenzyl isocyanate) (P(S-co-TMI)) copolymer. The combination of these strategies provides an elegant tool for the elaboration of a wide variety of multifunctional hyperbranched structures.

Synthesis of S-Linked N-Acetylneuraminic Acid Derivatives via Photoinduced Thiol-ene and Thiol-yne Couplings

Thio-linked mono- and bivalent mimetics of α(2→3) and α(2→6)-linked sialosides were prepared by photoinduced hydrothiolation of alkenes and alkynes with the 2-mercapto sialic acid. Thiosialylation of 6-O-allyl- or 3-O-allyl-substituted galactose derivatives has been carried out by the thiol–ene click reaction. Double thiosialylation has also been achieved via thiol–yne chemistry using propargylated galactose derivatives as the alkyne components and the peracetylated 2-mercapto sialic acid as the thiol.

ChemInform Abstract: Recent Applications of Thiol—Ene Coupling as a Click Process for Glycoconjugation

AbstractReview: 56 refs.

Thiol–yne ‘click’ chemistry as a route to functional lipid mimetics

Thiol–alkyne ‘click’ chemistry is a modular, efficient mechanism to synthesize complex A2B 3-arm star polymers. This general motif is similar to a phospholipid where the A blocks correspond to lypophilic chains and the B block represents the polar head group. In this communication we employ thiol–yne chemistry to produce polypeptide-based A2B lipid mimetics. The utility of the thiol–yne reaction is demonstrated by using a divergent and a convergent approach in the synthesis. These polymers self-assemble in aqueous solution into spherical vesicles with a relatively narrow size distribution independent of block composition over the range studied. Using the thiol–yne convergent synthesis, we envision a modular approach to functionalize proteins or oligopeptides with lipophilic chains that can imbed seamlessly into a cell membrane.

Hyperbranched alternating block copolymers using thiol–yne chemistry: materials with tuneable properties

Alternating-block hyperbranched polymers were synthesized using the highly versatile thiol-yne reaction. Dimethyl acrylamide-styrene and tert-butyl acrylate-styrene polymers were prepared, with subsequent hydrolysis of the tert-butyl ester to acrylic acid. The dimethyl acrylamide-styrene hyperbranched polymers self-assembled into large aggregates, as did the acrylic acid-styrene system at low pH. However, high pH triggers the formation of very well defined small particles in the latter system.

Preparation of emulsion-templated porous polymers using thiol–ene and thiol–yne chemistry

Highly porous polymeric materials are prepared by thiol–ene and thiol–yne mediated network formation using high internal phase emulsion templates. The efficiency of network formation is between 80 and 90% for all materials while the thiol–yne materials display enhanced strength and toughness due to their higher degree of crosslinking.