Cyclic Olefin Research Articles

PHYSICOCHEMICAL PROPERTIES AND BIOFLOCCULATING EFFICIENCY OF POLAR RESIDUE OF PARTITIONED EXTRACT OF TELFAIRIA OCCIDENTALIS LEAF

Water contamination has become more pronounced as a result of human economic growth all over the world. This study investigated the physicochemical properties and bioflocculating activity of the polar residue of partitioned extract (PRPE) of Telfairia occidentalis leaf. The bioflocculating activity of the extract was evaluated for optimum dosage, pH, temperature, and metal ion using Kaolin clay suspension; the optimum activities obtained were used in wastewater treatment. The optimum flocculating activity of the PRPE was obtained at the dose of 1 mg/mL, pH of 4, the temperature of 50°C, and divalent cation (Ca2+). The physicochemical characteristics of removal of turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and heavy metals were determined before and after treatment. Upon treatment of two different domestic wastewaters (DW1 & DW2), the physicochemical parameters were reduced except for nitrate and turbidity, which increased for DW2. The bioflocculant displayed the highest activity in DW1 with turbidity removal of 74%, TSS removal of 48%, nitrate removal of 24%, BOD and COD removal of 87.5% and 50% respectively. Heavy metals were also removed effectively in DW1 compared to DW2. The FTIR characterization revealed the presence of primary amine (N-H), cyclic alkene (C=C), phenol (O-H), sulfoxide (S=O) and, halo compound (C-Br) groups present in the bioflocculant which are essential as they promote the flocculation process. The findings from this study attest to the ability of PRPE of Telfairia occidentalis to act as a flocculant.

The role of monomer geometry on the properties of polyolefins: A numerical study

AbstractWe explore the role of monomer geometry on the structural, dynamic, and thermodynamic properties of polyolefis by employing all‐atom molecular dynamic simulations. Specifically, we compare properties of atactic polyolefins in the molten state including polypropylene (aPP), a short‐chain branched polymer: poy(1‐hexene) (aPH), and a polymer having cyclic olefins: poly(vinyl cyclobutane) (aPVCB). We find polymers having the same chain mass and atom composition (hydrocarbon‐based molecules), but having different monomer architecture differ strongly in material properties. In particular, the polymer glass transition () and bulk modulus () show higher values for aPVCB in comparison to aPP and aPH. This increase is caused by having the carbon atoms in a cyclic structure, making aPVCB achieve higher mass and energy densities. By contrast, adding linear short side chains to polymer backbones causes a reduction in and , since side chains make backbones displace each other reducing their packing and thus their mass and energy densities. More broadly, our numerical results suggest that the incorporation of VCB monomers to linear polyolefins will enhance their properties, opening the possibility for designing a new set of materials.

Enhancing fabrication of hybrid microfluidic devices through silane‐based bonding: A focus on polydimethylsiloxane‐cyclic olefin copolymer and PDMS‐lithium niobate

AbstractEffective manipulation and control of fluids in microfluidic channels requires robust bonding between the different components. Polydimethylsiloxane (PDMS) is widely employed in microchannel fabrication due to its affordability, biocompatibility, and straightforward fabrication process. However, PDMS's low surface energy poses challenges in bonding with many organic and inorganic substrates, hindering the development of hybrid microfluidic devices. In this study, a simple and versatile three step process is presented for bonding PDMS microchannels with organic (cyclic olefin copolymer (COC)) and inorganic substrates (lithium niobate (LiNbO3)) using plasma activation and a silane coupling agent. Initially, the PDMS surface undergoes oxygen/argon plasma activation, followed by functionalization with (3‐aminopropyl) triethoxysilane (APTES). Subsequently, the COC or LiNbO3 is plasma activated and brought into contact with PDMS under a load at a specific temperature. Characterization by Fourier transform infrared, scanning electron microscopy, atomic force microscopy, and contact angle measurements confirmed the successful treatment of the substrates. In addition, bonding strength of the fabricated hybrid devices was assessed through leakage and tensile tests. Under optimized conditions (100°C and 4% v/v APTES), PDMS‐COC hybrid microchannels achieved a flow rate of 600 mL/h without leakage and a tensile strength of 562 kPa. Conversely, the PDMS‐ LiNbO3 assembly demonstrated a flow rate of 216 mL/h before leakage, with a tensile strength of 334 kPa. This bonding method exhibits significant potential and versatility for various materials in microfluidic applications, ranging from biomedical research to enhanced oil recovery.

Single Step Isolation of Extracellular Vesicles from Large-Volume Samples with a Bifurcated A4F Microfluidic Device.

Extracellular vesicles (EVs) hold immense potential for various biomedical applications, including diagnostics, drug delivery, and regenerative medicine. Nevertheless, the current methodologies for isolating EVs present significant challenges, such as complexity, time consumption, and the need for bulky equipment, which hinders their clinical translation. To address these limitations, we aimed to develop an innovative microfluidic system based on cyclic olefin copolymer-off-stoichiometry thiol-ene (COC-OSTE) for the efficient isolation of EVs from large-volume samples in a continuous manner. By utilizing size and buoyancy-based separation, the technology used in this study achieved a significantly narrower size distribution compared to existing approaches from urine and cell media samples, enabling the targeting of specific EV size fractions in future applications. Our innovative COC-OSTE microfluidic device design, utilizing bifurcated asymmetric flow field-flow fractionation technology, offers a straightforward and continuous EV isolation approach for large-volume samples. Furthermore, the potential for mass manufacturing of this microfluidic device offers scalability and consistency, making it feasible to integrate EV isolation into routine clinical diagnostics and industrial processes, where high consistency and throughput are essential requirements.

Diazene-Catalyzed Oxidative Alkyl Halide-Olefin Metathesis.

The first platform for oxidative alkyl halide-olefin metathesis is described. The procedure employs diazenes as catalysts, which effect the cyclization of alkenyl alkyl halides to generate cyclic olefins and carbonyl products. The synthesis of phenanthrene, coumarin, and quinolone derivatives is demonstrated as well as the potential to apply this strategy to other electrophiles.

Investigation on discoloration mechanism of cyclic olefin copolymer under ionizing irradiation sterilization

Cyclic olefin copolymer (COC) is a material used in various aspects of medical and health fields due to its excellent comprehensive properties. When sterilized by ionizing irradiation, COC is typically exposed to an absorbed dose <25 kGy, yet noticeable discoloration still occurs. In this study, the COC with norbornene content of 52 mol.% was taken as the research subject to investigate the discoloration mechanism of the COC upon irradiation. After γ-ray irradiation, the transparent and colorless COC changed to varying degrees of yellowish-green. However, after 24 days of storage at room temperature, this color significantly diminished. The color change in COC after gamma irradiation primarily results from the presence of free radicals, which gradually fade through recombination. By employing time-dependent density functional theory simulations to analyze the UV–vis absorption spectrum of free radicals, the cause for the color change was illustrated. Additionally, it is worth noting that the faded sample can be recolored through re-irradiation, indicating a ``reversible change'' in coloration caused by gamma irradiation.

Ruthenium catalyzed efficient hydroformylation regulated by thiazolinyl-based phosphine

A catalytic system comprised of Ru3(CO)12, thiazolinyl-based phosphine (L1), and HBF4 enables the efficient hydroformylation, which the tautomer L1b is more favorable for the occurrence of the reaction as well as the additive HBF4 is beneficial for the formation of ruthenium hydrogen active species. The formation and stabilization of the critical Ru-complex intermediates were verified by the DFT calculations. The hydroformylation proceeds with high chemical selectivity especially for the linear, internal and cyclic olefins (conversion up to 99 %, selectivity of aldehysdes up to 92 %).

Cyclic Olefin Copolymer Based Photonic Crystal Fiber as Single Mode THz Waveguide

Cyclic Olefin Copolymer Based Photonic Crystal Fiber as Single Mode THz Waveguide

Catalytic C[sbnd]H activation-initiated transdiannulation: An oxygen transfer route to ring-fluorinated tricyclic γ-lactones

Catalytic CH activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry. Herein, we describe a new Rh(III)-catalyzed CH activation-initiated transdiannulation reaction of N,N-dimethyl enaminones with gem-difluorocyclopropenes in the presence of H2O, enabling a facile and oxygen transfer access to ring-fluorinated tricyclic γ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter. This approach features bond-forming/annulation efficiency, good functional group tolerance and complete regioselectivity, which may include a complex process consisting of Rh(III)-catalyzed C(sp2)H activation, cyclic alkene insertion, defluorinated ring-opening of gem-difluorocyclopropane, intramolecular oxygen transfer, intramolecular cyclization and oxidative hydration.

Visible-Light-Mediated Selective Allylic C–H Oxygenation of Cycloalkenes

AbstractA visible-light-mediated selective allylic C–H bond oxygenation of cyclic olefins is presented. Hence, the selective, mild monooxygenation of simple cycloalkenes has been achieved using an acridinium photoredox catalyst in combination with a phosphate base and a disulfide HAT reagent under air atmosphere at room temperature. The combination of both photocatalyst and HAT reagent, which can operate through a single or two different concurrent mechanistic pathways for the formation of the allyl radical, proved highly efficient, while the reaction with exclusively one or the other mediator performs in significantly lower yields. The formed allyl radical further reacts with a molecule of oxygen to build the corresponding peroxyradical that can abstract a hydrogen atom of another cycloalkene substrate, generating the known hydroperoxide intermediate in the formation of the ketone moiety. The advantages of this method rely on the easy use of air as oxygen source, as well as the selective monooxygenation of cycloalkenes without substitution in one of the allylic positions. Besides simple cyclic olefins, the method was also successfully applied in the oxidation of natural products such as the terpene valencene or cholesterol derivatives.

Birefringence in Injection-Molded Cyclic Olefin Copolymer Substrates and Its Impact on Integrated Photonic Structures.

This contribution quantifies the birefringence within injection-molded cyclic olefin copolymer plates and discusses its impact on the mechanical properties of the plates. It also focuses on the impact of birefringence on integrated waveguides and Bragg gratings and provides fabrication guidelines for such structures. The anisotropy in all three dimensions of the workpiece is examined by means of polarimetry and a prism coupler. It is found that the birefringence is inhomogenously distributed within the workpieces, whereas the maximum birefringence not only varies locally, but also depends on the observation direction. Overall, a maximum birefringence of 10 × 10-4 is found at the plate's surface near the injection gate. The anisotropy then reduces exponentially towards the center of the workpiece and saturates at 1.8 × 10-4, in a depth of 0.4 mm. Thus, the birefringence strongly affects near-surface photonic structures. It is found that, depending on their orientation and the local birefringence of the substrate, waveguides and Bragg gratings fabricated with comparable parameters behave completely differently in terms of polarization-dependent optical attenuation, cross-sectional intensity distribution and Bragg reflection signal. For example, the support of the TM mode can vary between total loss and an optical attenuation of 0.9 dB × cm-1. In consequence, this study underlines the importance of quantifying the birefringent state of an injection-molded cyclic olefin copolymer workpiece if it is supposed to serve as a substrate for integrated photonic structures. The study furthermore demonstrates that birefringence effects can be omitted by burying the photonic structures deeper into the volume of the thermoplastic.

Melt‐reprocessable linear low‐density polyethylene/cyclic olefin copolymer blends with low dielectric constant and low thermal expansion

AbstractInsulation materials with low dielectric constants, low coefficients of thermal expansion (CTE), low densities, renewability, and low cost are urgently needed in the fields of communication, control and signal cables. Here we report that combining cyclic olefin copolymer (COC) with linear low‐density polyethylene (LLDPE) by melt blending achieves the above goals. The dielectric constant and CTE of LLDPE/COC blends are minimized at 20 wt% COC content, reaching a value of 2.23 at 1000 Hz and 1.21 × 10−4 K−1, respectively. The density of the blend increases by only 1.6% compared with LLDPE, whereas the tensile modulus increases by 56%, which is conducive to the blends to improve mechanical strength while preserving lightweight. The rheological tests show that the zero‐shear viscosity, storage modulus, and loss modulus of the LLDPE/COC blends do not change much compared with pristine LLDPE, maintaining their good melt processability at 160°C. The cyclic rigid structure of COC causes a decrease in CTE, and the increase in free volume between molecular chains is responsible for the reduced dielectric constant. The present work provides a promising route to the design and fabrication of melt‐reprocessable polymer composites with low dielectric constant and low thermal expansion.

Photo-induced 1,2-alkylarylation/cyclization of alkenes, alkyl halides and N-alkylindoles via an EDA-complex

Herein, we developed a photo-induced 1,2-alkylarylation and 1,2-alkylarylation cyclization of alkenes, alkyl halides and N-alkylindoles to synthesize indoles derivatives and polysubstituted tetrahydrofuran under mild conditions without the use of external redox reagents and photosensitizers.

Advances in photoinduced radical–polar crossover cyclization (RPCC) of bifunctional alkenes

Photoinduced radical–polar crossover cyclization (RPCC) of bifunctional alkenes is of high synthetic utility to produce cyclic products with precise alkene design. This review summarizes the recent representative advances in the field of RPC.

Detection and identification of single ribonucleotide monophosphates using a dual in-plane nanopore sensor made in a thermoplastic via replication.

We report the generation of ∼8 nm dual in-plane pores fabricated in a thermoplastic via nanoimprint lithography (NIL). These pores were connected in series with nanochannels, one of which served as a flight tube to allow the identification of single molecules based on their molecular-dependent apparent mobilities (i.e., dual in-plane nanopore sensor). Two different thermoplastics were investigated including poly(methyl methacrylate), PMMA, and cyclic olefin polymer, COP, as the substrate for the sensor both of which were sealed using a low glass transition cover plate (cyclic olefin co-polymer, COC) that could be thermally fusion bonded to the PMMA or COP substrate at a temperature minimizing nanostructure deformation. Unique to these dual in-plane nanopore sensors was two pores flanking each side of the nanometer flight tube (50 × 50 nm, width × depth) that was 10 μm in length. The utility of this dual in-plane nanopore sensor was evaluated to not only detect, but also identify single ribonucleotide monophosphates (rNMPs) by using the travel time (time-of-flight, ToF), the resistive pulse event amplitude, and the dwell time. In spite of the relatively large size of these in-plane pores (∼8 nm effective diameter), we could detect via resistive pulse sensing (RPS) single rNMP molecules at a mass load of 3.9 fg, which was ascribed to the unique structural features of the nanofluidic network and the use of a thermoplastic with low relative dielectric constants, which resulted in a low RMS noise level in the open pore current. Our data indicated that the identification accuracy of individual rNMPs was high, which was ascribed to an improved chromatographic contribution to the nano-electrophoresis apparent mobility. With the ToF data only, the identification accuracy was 98.3%. However, when incorporating the resistive pulse sensing event amplitude and dwell time in conjunction with the ToF and analyzed via principal component analysis (PCA), the identification accuracy reached 100%. These findings pave the way for the realization of a novel chip-based single-molecule RNA sequencing technology.

Copolymerization of tricyclopentadiene and ethylene catalyzed by thiophene-fused-heterocyclic cyclopentadienyl scandium complexes

Tricyclopentadiene–ethylene copolymerization catalysed by scandium complexes and post-hydrogenation of the resultant copolymers with H2 were achieved. The hydrogenated polymers show high glass-transition temperatures and high transparency.

Fine-tuning of organic optical double-donor NLO chromophores with DA-supported functional groups.

New strategic chromophores with updated fine-tuning of previously reported BLD1 and BLD3 chromophores were designed. BLD1 and BLD3 have silicon functional groups on the donor unit, and the bridge has a good chance of self-assembling, so in the present study we fine-tuned the isolating groups to the bulky cyclic alkene to improve their dipole moment and organic electro-optic (OEO) properties as well. To demonstrate the impact of cyclic alkenes on the electron-donating groups in sensible NLO chromophore designs, a thorough analysis and comparison of the chromophore synthesis, UV-Vis calculations, solvatochromic behavior of the chromophore, DFT quantum mechanical calculations, thermal stabilities, and much lower dipole moments was conducted.

Regioselective tandem sulfonylation/cyclization of unsaturated N-substituted enamides with sulfonyl chlorides by copper catalysis

The radical cascade cyclization of vinyl-tethered alkenes has become a promising tool for rapidly assembling nonbenzene-fused cyclic skeletons via the cracking of alkenyl C–H bonds, but this approach has been limited to generate five-membered rings.

Iridium-catalysed hydroamination of internal homoallylic amines.

An Ir-catalysed regioselective hydroamination of internal homoallylic amines is reported. Both cyclic and acyclic internal olefins undergo directed hydroamination reactions with both aromatic and cyclic aliphatic amines to afford a variety of 1,4-diamines in fair to excellent yields. Diastereoselectivity and mechanistic investigations support that for cyclic substrates the reactions are proceeding via trans-aminoiridation to form a 5-membered metalacyclic intermediate.

Metal-free phosphine-catalyzed visible-light-induced radical cyclization of alkenes: access to cyclic gem-difluoroacyl scaffolds

Visible-light-induced phosphine-catalyzed radical cyclization of bromodifluoroacyl arenes with diverse alkenes, affording a variety of cyclic gem-difluoroacyl scaffolds in good to excellent yields.