Search Results (331)

With the constant development of new polymer chemistry technologies, it is necessary to find modern synthetic pathways for the synthesis of polymers bearing numerous applicable characteristics, in an easy, efficient and environmentally friendly way. One such possibility is to present the use of metathesis type reactions and more specifically ring-opening metathesis polymerisation (ROMP), which provides the opportunity to produce linear unsaturated functionalised polymeric chains in a ‘living’ yet controlled manner with the use of ruthenium-based carbene (Ru=CHR) Grubbs’ catalysts (initiators: G1, G2, G3). In order to achieve satisfying results and obtain full conversion of the monomers, sterically hindered molecules are preferred, because the process of opening the ring results in simultaneous release of the energy that propagates the whole process. The incorporation of silicon-based substituents (such as silyl ethers) into the norbornene matrix can provide higher thermal stability of polymers, leading to the creation of flame-retardant materials. Other applications include gas separation membranes or biomedicine, upon further modification. This paper focusses on the development and optimisation of the synthetic method of previously not reported exo-norbornene silyl ethers along with their metathesis polymerisation to achieve linear unsaturated polymers with high isolation yields. Full article

A modular synthetic route has been developed to prepare a new series of cationic ruthenium(II) complexes with electron-withdrawing 1,2-diacylcyclopentadienyl ligands. The 2-acyl-6-hydroxyfulvenes were synthesized from cyclopentadienide and acyl chlorides and converted to Tl(I) cyclopentadienyl salts using Tl₂SO₄/KOH. Transmetalation with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ followed by PF₆⁻ metathesis gives the complexes [Ru{η⁵-1,2-C₅H₃(CO–R)₂}(η⁶-p-cymene)][PF₆] (R = t-Bu, p-Tol, p-ClC₆H₄, p-IC₆H₄) in moderate to high yields. The new compounds were characterized by NMR and IR spectroscopy; mass spectrometry and elemental analysis were performed where applicable. X-ray analysis of one of the complexes confirms that electron-deficient Cp ligands retain η⁵-coordination and structural planarity within Ru(II)–arene sandwich architectures, highlighting their potential utility in electronically tunable organometallic frameworks. Full article

1,4-Disubstituted 1,2,3-triazoles are readily obtained by copper(I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition (CuAAC)—the most widespread illustration of click chemistry to date. 1,2,3-Triazoles form a vast and easily accessible library of precursors for synthesizing 1,2,3-triazolium ionic liquids (TILs). A series of four 1,3,4-trisubstituted TILs with N-1-n-octyl, N-3-methyl and different C-4 substituents (i.e., aromatic, aliphatic, PEGylated and perfluorinated groups) is synthesized in two steps involving: (i) CuAAC to generate 1,2,3-triazole precursors and (ii) N-alkylation of the 1,2,3-triazole groups with methyl iodide to afford the corresponding 1,2,3-triazolium salts with iodide counter-anions. A thorough investigation of the correlations between structure and properties is carried out using NMR spectroscopy, high-resolution mass spectrometry, differential scanning calorimetry, thermogravimetric analysis and broadband dielectric spectroscopy. The PEGylated TIL has also undergone ion metathesis to produce the TIL analogue with a bis(trifluoromethylsulfonyl)imide counter-anion. Of all the synthesized TILs, this derivative exhibits the lowest glass transition temperature (T_g = −76 °C), the highest thermal stability (T_d10 = 345 °C) and the greatest ionic conductivity (σ_DC = 6.5 × 10⁻⁴ S cm⁻¹ at 30 °C under anhydrous conditions). Full article

Polydicyclopentadiene (PDCPD), an emerging environmentally friendly material, has been widely applied in lightweight structural shells; however, its extension to high-value electronic applications remains challenging. In this work, we developed a novel vinyl-SiO₂@NaNbO₃ (VSN) core–shell structure with a high surface vinyl concentration (1.26 mmol/g) and excellent thermal stability, making it highly suitable for co-polymerization with polymers. Through ring-opening metathesis polymerization, the influence of VSN on the mechanical, thermal, and dielectric properties of PDCPD composites was systematically investigated. The vinyl groups on the VSN surface provide strong interfacial compatibility with the PDCPD matrix. With only 1.0 wt% loading, the composites show significant performance improvements: the heat deflection temperature and glass transition temperature increased to 139.3 °C and 150.43 °C, respectively, while the dielectric constant at 1 kHz rises to 4.13 with an ultralow dielectric loss of 0.035%. Meanwhile, the composites maintain high mechanical strength and solvent resistance. This study not only establishes a facile strategy for fabricating highly compatible inorganic additives but also offers new opportunities for expanding PDCPD into advanced dielectric and electronic applications. Full article

The reactive double dividing-wall distillation column (R-DDWDC) can simultaneously integrate and effectively coordinate reaction–separation coupling (RSC) and separation–separation coupling (SSC), thereby offering greater technical advantages and development potential than the conventional reactive distillation column and the reactive single dividing-wall distillation column. However, the application of two dividing walls and the introduction of external recycle flows inevitably lead to multiple candidate configurations of the R-DDWDC, and this significantly adds complexity and computational burden to its synthesis and design. To address the issue, we propose an effective methodology for developing the R-DDWDC, which involves a two-step strategy: the first step is to determine the configuration of external recycle flows by searching for the RSC from non-sharp separation to sharp separation of reaction mixtures, and the second step is to adjust the arrangement of the dividing walls to intensify the SSC. The former serves to provide the greatest flexibility for the inclusion of the SSC, and the latter helps to achieve full coordination with the RSC, thereby allowing the determination of the optimal design with low complexity and computational intensity. The methodology is fundamentally a conceptual design and structural optimization framework that can be implemented using either generic process simulation platforms or custom computational programs. Four representative examples, including the metathesis of 2-pentene; the acetalization of ethanol with butanal; the transesterification of propylene glycol monomethyl ether with methyl acetate; and the esterification of lactic acid with methanol, are selected to assess the derived procedure, and the obtained results confirm its simplicity and efficiency. Because the procedure proposed in this work is independent of the number of components contained in reaction mixtures and their relative volatility rankings, it can be regarded as a general methodology for developing other complicated reactive dividing-wall distillation columns. Full article

We herein demonstrate that the thiosemicarbazone (TSC) ligand N′-(di(pyridin-2-yl)methylene)-4-(thiazol-2-yl)piperazine-1-carbothiohydrazide (HL) can coordinate with Ga³⁺ to give cationic complex [Ga(L)₂]NO₃ featuring an octahedral Ga(III) center. [Ga(L)₂]NO₃ undergoes metathesis with both Fe²⁺ and Fe³⁺, resulting in the formation of respective Fe²⁺- and Fe³⁺ complexes. [Ga(L)₂]NO₃ is also susceptible to anion exchange with sodium hyaluronate (NaA) to produce the nanoformulation [Ga(L)₂]A with boosted aqueous solubility and cell targeting. [Ga(L)₂]A demonstrated remarkable in vitro cytotoxicity against NCI-H82 and A549 (lung cancer), as well as KYSE-510 and Te-1 (esophageal cancer) cell lines, featuring half maximal inhibitory concentration (IC₅₀) values in the range 0.102–2.616 μmol L⁻¹. This work highlights the potential of using non-toxic and biocompatible Ga³⁺ as the central ion to prepare TSC-based nanomedicines for combating cancer. Full article

A computational study of the mechanism of asymmetric hydrogenation of γ-keto acids with the Ni(S,S)-QuinoxP* system was conducted. The main steps of the reaction mechanism were determined, including the formation of the NiH(S,S-QuinoxP*)⁺ complex starting from a γ-keto acid molecule and the involvement of the hydrogen “metathesis” step. The rate-limiting and stereo-determining step of the reaction was identified as the transfer of a hydrogen atom from the catalytic particle to the carbonyl group of the substrate molecule. The stereochemical outcome of the process was calculated. The influence of weak interactions on the stereoselectivity of the process was demonstrated using NCI and sobEDAw analyses. Full article

The ruthenium-catalysed silylative coupling (SC) reaction is a useful method for obtaining selectively functionalised organosilicon compounds, which have a wide range of applications in organometallic and organic chemistry. It is possible to prepare such compounds with norbornene matrices, which can be used for ring-opening metathesis polymerisation (ROMP) in the synthesis of linear-type polymers. Herein, we present a method for the synthesis of the aforementioned matrices by a condensation reaction between diol and vinylphenylboronic acids. Furthermore, these compounds were subsequently modified by SC reaction and polymerised by ROMP. To assess the possibility of using styryl-based silyl-derived monomers as building blocks in further organic transformations, the process of bromodesilylation was also investigated. We would also like to perform a comparative study on the selectivity of hydrosilylation and silylative coupling processes in the case of discovered materials. Full article

This work reports on the synthesis and ring-opening metathesis polymerization (ROMP) of two novel homologous sulfonyl-containing norbornene dicarboximide monomers, specifically, N-4-(trifluoromethylsulfonyl)phenyl-norbornene-5,6-dicarboximide (1a) and N-4-(trifluoromethylsulfonyl)phenyl-7-oxanorbornene-5,6-dicarboximide (1b) using the Grubbs 2nd generation catalyst (I). The polymers are thoroughly characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermomechanical analysis (TMA), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and X-ray diffraction (XRD), among other techniques. A comparative study of gas transport in membranes based on these ROMP-prepared polymers is performed and the gases studied are hydrogen, oxygen, nitrogen, carbon dioxide, methane, ethylene and propylene. It is found that the presence of sulfonyl pendant groups in the polymer backbone increases the gas permselectivity in slight detriment of the gas permeability compared to a polynorbornene dicarboximide lacking sulfonyl groups. The membrane of the sulfonyl-containing polymer with an oxygen heteroatom in the cyclopentane ring, 2b, is also found to have one of the largest permselectivity coefficients reported to date for the separation of H₂/C₃H₆ in glassy polynorbornene dicarboximides. Full article

A series of poly(5-n-butyl-2-norbornene) oils with controlled molecular weights was synthesized via metathesis polymerization, fully hydrogenated, and characterized in terms of viscosity and tribological performance. In contrast to established lubricant base stocks—such as poly(α-olefins) and multiply alkylated cyclopentanes—these novel norbornene-based polymers remain underexplored, despite their promising anti-wear activity. Based on differential scanning calorimetry (DSC) data, all the synthesized products are amorphous compounds whose thermograms show a single glass transition temperature. The effect of molecular weight and temperature on the viscosity of poly(5-n-butyl-2-norbornene) oils was quantified over an extended temperature range, including extra-cold conditions down to −80 °C. The pour points of the oils were determined and can be as low as −66 °C, indicating excellent low-temperature fluidity. The tribological performance of the synthesized oils was evaluated using the four-ball test, with friction coefficient and wear scar diameter measured to assess anti-wear and antifriction properties. The tribological results were benchmarked against commercially available polyalphaolefin (PAO) oils (PAO-4, PAO-20, and PAO-80). Metathesis and hydrogenated poly(5-n-butyl-2-norbornene) oils outperform conventional PAOs by up to 67% in wear protection and 30% in friction reduction. These findings establish alicyclic molecular strain as a viable design parameter for next-generation lubricating oils, thereby expanding the toolbox for material development beyond conventional chemical functionalization. Full article

This study explores a disulfide-selective cross-linking strategy for natural rubber (NR) to formulate elastomeric materials with engineering-relevant mechanical properties. A disulfide-containing bismaleimide (BIS) cross-linker was synthesized from cystamine and maleic anhydride and compounded with NR. Three formulations were prepared: control (no inhibitor), CuCl₂-based, and copper(II) methacrylate (CuMA) based compounds, with BIS concentrations ranging from 3.55 to 8.88 phr. Rheological and mechanical testing revealed that CuCl₂ formulations suffered from molecular degradation, poor thermal stability, and mechanical brittleness due to oxidative reactions in the absence of antioxidants. In contrast, CuMA-based compounds exhibited intermediate molecular weights prior to curing, stable thermal behavior, and improved mechanical properties, including enhanced torque and tensile strength, indicating effective cross-linking and partial recyclability. The control formulations also performed reasonably well but did not match the mechanical strength of conventional sulfur-vulcanized NR. The results demonstrate that metal coordination, particularly with CuMA, can modulate disulfide metathesis kinetics and offer a pathway to thermally triggered network rearrangement. Overall, CuMA emerges as a promising candidate for developing high-performance, recyclable rubber materials, while CuCl₂ requires further stabilization strategies. This work establishes a baseline for future recyclability studies and advances the design of dynamic covalent networks in elastomers. Full article

Dynamic covalent bonds within polymer materials have been the subject of ongoing research. These bonds impart polymers, particularly thermosets, with capabilities for self-healing and reprocessing. Concurrently, three-dimensional (3D) printing techniques have undergone rapid advancement and widespread adoption. Since polymers are among the primary materials used in 3D printing, networks featuring dynamic covalent bonds have emerged as a prominent research area. This review outlines approaches for incorporating dynamic covalent bonds into polymers suitable for 3D printing and examines representative studies that leverage these chemistries in material design. Polymers produced using these strategies demonstrate both self-healing and reprocessability, primarily via bond-exchange (metathesis) reactions. In addition, we discuss how the type and amount of dynamic bonds in the network affect the resulting material properties, with particular emphasis on their mechanical, physical, and thermal performance. In particular, the introduction of dynamic covalent bonds seems to significantly improve the degree of anisotropy, which has been the limitation of 3D printing techniques. Finally, we compile recent applications for objects printed from polymers that include dynamic covalent bonds. Full article

Metathesis reactions of Ag[C(CN)₃] with anhydrous YbCl₃ dissolved in water combined with stoichiometric amounts of the alkali-metal salts A[C(CN)₃] (A = Na or K) yield the non-isotypic tetragonal compounds NaYb[C(CN)₃]₄ (P4/nnc with a = 1188.37(9) pm, c = 1232.41(9) pm) and KYb[C(CN)₃]₄ (P4/nbm with a = 1179.26(9) pm, c = 668.73(5) pm). Both crystal structures contain a three-dimensional framework (Niggli formula: $\begin{array}{c}3\\ \infty \end{array}${(Yb[C(CN)₃]_8/2)⁻}) with Yb³⁺ in square antiprismatic coordination of terminal nitrogen atoms (d(Yb–N) = 241–242 pm) from eight planar star-shaped tricyanomethanide anions [C(CN)₃]⁻. The Na⁺ or K⁺ cations occupy vacancies, which provide them with a tetrahedral coordination sphere of nitrogen (d(Na–N) = 239 pm vs. d(K–N) = 276 pm) from four [C(CN)₃]⁻ anions. This difference results from secondary contacts with the central carbon atoms (d(Na–C) = 361 pm vs. d(K–C) = 367 pm) of four different [C(CN)₃]⁻ units, which do not contribute to NaYb[C(CN)₃]₄, but effectuate a lot in the case of KYb[C(CN)₃]₄. The Raman spectrum recorded for NaYb[C(CN)₃]₄ corroborates the presence of a pseudo-D_3h-symmetric tricyanomethanide anion [C(CN)₃]⁻ and the absence of water. Full article

The rare earth (RE) aqua 4-nitrophenylacetate (4npa) complexes {[RE(4npa)₃(H₂O)₂]·2H₂O}_n (RE = La (1La), Nd (2Nd)), [Ce(4npa)₃(H₂O)₂]_n (3Ce), and {[RE₂(4npa)₆(H₂O)]·2H₂O}_n (RE = Gd (4Gd), Dy (5Dy), Y (6Y), Er (7Er), Yb (8Yb)) were synthesised by salt metathesis reactions of RE^III chlorides or nitrates with sodium 4-nitrophenylacetate Na(4npa) in aqueous ethanol. The structures of all the complexes were determined by single-crystal X-ray diffraction (SCXRD) except for RE = 4Gd, which was determined to be isomorphous with the 5Dy and 7Er complexes by X-ray powder diffraction (XRPD). All the complexes crystallise as one-dimensional polymers linked by bridging carboxylates. Complexes (1La–3Ce) have mononuclear repeating units with two coordinated waters and ten coordinate RE ions, 1La and 2Nd also have two waters of crystallization, but 3Ce has none. By contrast, complexes (4Gd–8Yb) have binuclear repeating units with a single coordinated water. Isomorphous 5Dy and 7Er have one nine coordinate and one eight coordinate metal ion, whilst isomorphous 6Y and 8Yb have two eight coordinate RE ions. In some cases, bulk powders have structures different from the corresponding single crystals. For example, bulk 1La is isomorphous with 3Ce owing to the loss of water of crystallization, and 8Yb exhibits coordination isomerism between single crystals and microcrystalline powder. Weight loss corrosion tests revealed that {[Dy₂(4npa)₆(H₂O)]·2H₂O}_n (5Dy) has the greatest inhibition efficiency (89%) of the complexes (1La–8Yb). The activities are comparable to those of the corresponding 4-hydroxyphenylacetates (4hpa) and far superior to those of 2-hydroxyphenylacetates (2hpa) and the unsubstituted phenylacetates. Whilst the coordination numbers generally decline with the lanthanoid contraction, there are deviations around 5Dy, 6Y, 7Er, and 8Yb, and the corrosion inhibition is optimised with a midrange size. Full article

Within recent years, the interest in tools to investigate carbohydrate-protein (CPI) and carbohydrate-carbohydrate interactions (CCI) has increased significantly. For the investigation of CPI and CCI, several techniques employing different linking methods are available. For mimicking the glycocalyx self-assembled monolayer (SAM) formation of carbohydrate derivatives on gold nanoparticles is most appropriate. In contrast to methods for glyco-SAM formation used previously to analyze CPI/CCI, the novel approach allows for a facile and rapid synthesis to link spacers and carbohydrate derivatives and enhances the binding event by controlling the amount and orientation of ligand. For immobilization on biorepulsive aminooxy functionalized gold nanoparticles by oxime coupling, diverse aldehyde-functionalized glycan structures of mono-, di-, and complex trisaccharides were synthesized, employing several facile steps including olefin metathesis. Effective immobilization and first binding studies are presented for the lectin concanavalin A. This novel and advantageous immobilization method is presently employed in various biomimetic studies of carbohydrates and carbohydrate-based array development for diagnostics and screening. Full article