Bond In Side Chain Research Articles

Adaptation mechanism of clam Ruditapes philippinarum under polycyclic aromatic hydrocarbon stresses: accumulation and excretion

Persistent organic pollutants (POPs) are easily accumulated in organisms due to its high lipophilicity. Bivalves are still one of the marine invertebrates with high species diversity despite experiencing with environmental pollution. However, studies investigating the adaptation mechanisms of bivalves towards POPs have been lacking. In this study, we chose benzo[a]pyrene (B[a]P), a typical POPs, to investigate the accumulation and excretion mechanism of clam Ruditapes philippinarum towards B[a]P. Laser confocal microscopy images of ovaries and testes confirmed significant colocalization between lipid droplets and B[a]P. However, B[a]P in the testes might mainly excrete with the excretory fluid. Furthermore, lipidomics results indicated that the upregulated TGs were TGs with 48-58 total carbon atoms and 6-12 double bonds in acyl side chains in ovaries, while the upregulated TGs mainly distributed in 48-58 total carbon atoms and 4-14 double bonds in acyl side chains in testes. In ovaries, gene expression of lipid metabolism and phospholipid metabolism basically presented an upward trend at Pro and Mat stages, while entirely performed a downregulation trend at Gro stage. Testes had the opposite regulation with that. Additionally, B[a]P prompted the excretion ability of female clams, but exhibited a complex effect in the male. This study provides a scientific basis for bivalve toxicology and healthy aquaculture, which is of great significance for marine ecological environment protection and aquatic product safety of China. Environmental ImplicationBivalves are an ancient class of animals that appeared 500 million years ago, and are still one of the marine invertebrates with high species diversity despite experiencing with global climate change and environmental pollution. Thus, explore the adaptation mechanism of bivalves under contaminant stress can generate responses for biodiversity conservation. In this study, we investigate the accumulation and excretion mechanism of clam Ruditapes philipinarum towards B[a]P. The results will provide a scientific basis for the protection of germplasm resources and healthy aquaculture, which is of great significance for marine ecological environment protection and aquatic product safety of China.

Pd catalysts in the mild reductive depolymerization of Soda lignin: Support and Cu addition effects

This study pioneers the exploration of the structure-performance relationship of 5 wt% Pd and PdCu catalysts on 3 supports (γ-Al2O3, SiO2, and activated carbon (AC)) in the mild reductive depolymerization (MRD) of Soda lignin. While all catalysts achieve similar final weight average molecular weight (Mw) reduction (≈ 85 %), Pd/AC and PdCu/AC show significant differentiation from solvolysis already after 2 h and 3 h, compared to 6 h and 20 h for Pd and PdCu on oxide supports. This study also highlights the importance of hydrogenation of C=C bonds in monomer side-chains for maximizing monomer yields. Particularly PdCu/SiO2 is characterized by the lowest monomer yields (7 wt%) due to its low hydrogenation activity, while catalysts like Pd(Cu)/Al2O3, Pd/SiO2, and Pd/AC, with more expressed hydrogenation, achieve a total monomer yield of up to 14 wt%. Additional findings confirm that on γ-Al2O3, the co-impregnation of Cu and Pd leads to the formation of a chemical bond between Pd2+ and Cu1+, resulting in a new mixed metal oxide Pd-Cu–O phase. On SiO2, Pd2+ and Cu1+ do not form a chemical bond, however, the presence of Cu1+ in close proximity to Pd2+ significantly alters the selectivity of the PdCu/SiO2 catalyst due to synergetic effects. PdCu/AC maintains similar selectivity to Pd/AC, except for reduced hydrogenation over time, due to the lack of interaction between Pd and Cu on the AC surface. This research also delves into the MRD mechanism of Soda lignin over Pd and PdCu catalysts, focusing on the β-O-4 linkage cleavage and the subtle differences in reaction pathways depending on the catalyst. These findings bridge gaps in understanding the MRD of actual lignin feedstocks, offering valuable insights for catalyst development and process optimization.

7-Deazapurine and Pyrimidine Nucleoside and Oligonucleotide Cycloadducts Formed by Inverse Diels-Alder Reactions with 3,6-Di(pyrid-2-yl)-1,2,4,5-tetrazine: Ethynylated and Vinylated Nucleobases for Functionalization and Impact of Pyridazine Adducts on DNA Base Pair Stability and Mismatch Discrimination.

The manuscript reports on 7-deazapurine and pyrimidine nucleoside and oligonucleotide cycloadducts formed by the inverse electron demand Diels-Alder (iEDDA) reaction with 3,6-di(pyrid-2-yl)-1,2,4,5-tetrazine. Cycloadducts were constructed from ethynylated and vinylated nucleobases. Oligonucleotides were synthesized containing iEDDA modifications, and the impact on duplex stability was investigated. iEDDA reactions were performed on nucleoside triple bond side chains. Oxidation was not required in these cases as dihydropyridazine intermediates are not formed. In contrast, oxidation is necessary for reactions performed on alkenyl compounds. This was verified on 5-vinyl-2'-deoxyuridine. A diastereomeric mixture of 1,2-dihydropyridazine cycloadduct intermediates was isolated, characterized, and later oxidized. 12-mer oligonucleotides containing 1,2-pyridazine inverse Diels-Alder cycloadducts and their precursors were hybridized to short DNA duplexes. For that, a series of phosphoramidites was prepared. DNA duplexes with 7-functionalized 7-deazaadenines and 5-functionalized pyrimidines display high duplex stability when spacer units are present between nucleobases and pyridazine cycloadducts. A direct connectivity of the pyridazine moiety to nucleobases as reported for metabolic labeling of vinyl nucleosides reduced duplex stability strongly. Oligonucleotides bearing linkers with and without pyridazine cycloadducts attached to the 7-deazaadenine nucleobase significantly reduced mismatch formation with dC and dG.

Systematic Characterization of Triterpenoids in Ganoderma lucidum by UHPLC-Q/TOF MS

Background: Ganoderma lucidum, which is widely used as “Ganoderma” in China or other Asian countries (Japan, Korea, etc), exerts an important role in tonifying qi and calming the mind in clinical applications. Triterpenoids are the main active components in Ganoderma lucidum, with significant biological activities of hepatoprotective, anticancer, and anti-tumor, etc. However, the current analysis of triterpenoids in Ganoderma lucidum by mass spectrometry is limited, restricting its quality control and elucidation of its functional basis. Objective: This work aimed to systematically characterize the triterpenoids in Ganoderma lucidum. Methods: The Ganoderma lucidum powder was extracted by 50% ethanol/water and separated by Waters ACQUITY UPLC HSS T3 column (2.1 mm×100 mm, 1.8 μm). The data was obtained by Waters G2-Q-TOF mass spectrometry equipped with an electrospray ionization ion (ESI) source, and the MS data under positive and negative modes was acquired and analyzed. Results: A total of 43 triterpenoids were identified or tentatively characterized from the extracts of Ganoderma lucidum, including 32 known compounds and 11 potential new compounds. Among them, five triterpenoids were unambiguously identified by comparison with reference standards, including ganoderic acid A(28), ganoderic acid D(36), ganoderenic acid D(34), ganoderic acid F(43), and ganoderic acid G(16). The profiled triterpenoids could be divided into eight types according to the substituents at the C3, C7 and C15 positions of the parent structure. The mass fragmentation rules of Ganoderma lucidum triterpenoids were summarized. Under the positive ion mode, Ganoderma lucidum triterpenoids easily lost CH3 at the C10 position and H2O at C3, C7, and C15 positions, and the side chain bond at the C22(23) position was easily split. Under the negative ion mode, the split of the C and D rings was the characteristic feature. result: A total of 43 triterpenoids were identified or tentatively characterized from the extracts of Ganoderma lucidum, including 32 known compounds and 11 potential new compounds. Among them, five triterpenoids were unambitiously identified by comparison with reference standards, including ganoderic acid A(28), ganoderic acid D(36), ganoderenic acid D(34), ganoderic acid F(43), and ganoderic acid G(16). These triterpenoids could be divided into eight types according to the substituents at the C3, C7 and C15 positions of the parent structure. The mass fragmentation rules of Ganoderma lucidum triterpenoids were summarized. Under the positive ion mode, Ganoderma lucidum triterpenoids easily lost CH3 at the C10 position and H2O at C3, C7, C15 position, and the side chain bond at C22(23) position was easily cracked. Under the negative ion mode, the crack of the C and D rings was the characteristic feature. Conclusion: The mass fragmentation behaviors of Ganoderma lucidum triterpenoids under positive ion mode were summarized and emphasized, and reliable scientific data and methods for systematic characterization of Ganoderma lucidum triterpenoids were also supplied.

Acyclic nucleosides via allylic amination of 2-methylidenetrimethylene carbonate with N-heteroaromatics

A highly efficient Pd-catalyzed allylic amination reaction using N-heteroaromatics to react with 2-methylidenetrimethylene carbonate was achieved (24 examples, up to 95 % yield, up to >20:1 N9/N7 selectivities). The presented strategy offers an efficient and convenient approach to construct acyclic nucleosides with a double bond in side chain.

Principles for designing sustainable and high-strain rate stress wave dissipating materials.

Dynamic covalent networks serve as effective tools for dissipating high-strain rate mechanical energy throughout reversible bond exchange reactions. Despite their potential, a gap exists in understanding how polymer chain mobility and the kinetics of bond exchange reactions impact the energy dissipating capabilities of dynamic covalent networks. This study presents an optimal strategy to enhance energy dissipation by controlling the side chain structures and bond exchange rates of dynamic covalent networks. Lipoic acid-derived polymers are chosen as our model system due to their easily tunable side chains and disulfide-rich backbones. High-strain rate stress waves are subjected to the polymers using a laser-induced shock wave technique. A strong correlation is observed between the energy dissipation capability and the glass transition temperature of the poly(disulfide)s. Furthermore, the addition of a catalyst to accelerate the disulfide exchange reaction improves energy dissipation. Leveraging the inherent nature of cyclic disulfides, our polymers exhibit self-healing and chemical recycling to monomers. The principles observed in this study provide a rational framework for designing sustainable and efficient energy dissipating materials.

Physically crosslinked polyacrylates by quadruple hydrogen bonding side chains.

Dynamic polymer materials can be obtained by introducing supramolecular interactions between the polymer chains. Here we report on the preparation and mechanical properties of poly(methyl acrylate) (PMA) and poly(n-butyl acrylate) (PBA) funcionalized with ureidopyrimidinone (UPy) in the side chains. In contrast to the traditional UPy with a methyl group, the selected UPy motif contained a branched alkyl side chain, which enhances solubility, compatibility with the polymer matrix and potentially prevents stacking of UPy dimers. Low molar mass PMA and PBA were synthesized via Cu(0)-mediated radical polymerization and allyl bonds were introduced with different degrees of functionalization by stoichiometrically controlled transesterification with allyl alcohol. The allyl esters served as functional handles for UPy attachment via UV-initiated radical thiol-ene coupling. The PMA-UPy materials displayed a more glassy appearance, in contrast to the rubbery PBA-UPy polymer networks, associated to its higher glass transition temperature. The mechanical properties of the resulting hydrogen bonded polymer networks were assessed by thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical thermal analysis and tensile testing, followed by rheological analysis of the network dynamics. Furthermore, the effect of associative groups on the linear viscoelastic response is discussed based on a modified sticky Rouse model indicating the absence of significant aggregation or phase separation of the UPY units.

Influence mechanism of UVIV on DC surface flashover performances of silicone rubber: From molecule modification to macroscopic characteristics improvement

In surface science, surface flashover, which poses a severe danger to the safe operation of modern silicone rubber (SIR)-based electrical equipment, is a continuous discharge event that happens when an intense electric field is produced along the gas-solid interface. To improve the flashover performance, the ultraviolet irradiation in vacuum (UVIV) technique is proposed to modify the SIR surface and the DC flashover threshold increases approximately 14.8 % after 6 h UVIV treatment. Then, the influence mechanisms of UVIV are investigated from microscopic molecule modification to macroscopic flashover performance: The UVIV generates high-energy photons to break CH and SiC bonds in SIR chains, and atoms, group, side chains, and free radicals in chains recombine through the thermally dynamic, causing SIR chains to crosslink. The crosslink chain structure enhances the deep trap energy around the SiOSi bond and introduces large amounts of deep traps. The increment in surface deep trap energy and density captures electrons. It establishes a high electrostatic near the cathode barrier that impedes subsequent electron injection, causing surface charge density decreases far away from the cathode. The reduced surface charges restrict the collision ionization in gas, finally increasing the DC surface flashover voltage through UVIV treatment.

Effects of Side Chain and Peptide Bond Modifications on the Targeting Properties of Stabilized Minigastrin Analogs.

Different attempts have been made in the past two decades to develop radiolabeled peptide conjugates with enhanced pharmacokinetic properties in order to improve the application for tumor imaging and peptide receptor radionuclide therapy (PRRT), which targets the cholecystokinin-2 receptor (CCK2R). In this paper, the influence of different side chain and peptide bond modifications has been explored for the minigastrin analog DOTA-DGlu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1Nal-NH2 (DOTA-MGS5). Based on this lead structure, five new derivatives were synthesized for radiolabeling with trivalent radiometals. Different chemical and biological properties of the new derivatives were analyzed. Receptor interaction of the peptide derivatives and cell internalization of the radiolabeled peptides were studied in A431-CCK2R cells. The stability of the radiolabeled peptides in vivo was investigated using BALB/c mice. Tumor targeting of all 111In-labeled peptide conjugates, and of a selected compound radiolabeled with gallium-68 and lutetium-177, was evaluated in BALB/c nude mice xenografted with A431-CCK2R and A431-mock cells. All 111In-labeled conjugates, except [111In]In-DOTA-[Phe8]MGS5, showed a high resistance against enzymatic degradation. A high receptor affinity with IC50 values in the low nanomolar range was confirmed for most of the peptide derivatives. The specific cell internalization over time was 35.3-47.3% for all radiopeptides 4 h after incubation. Only [111In]In-DOTA-MGS5[NHCH3] exhibited a lower cell internalization of 6.6 ± 2.8%. An overall improved resistance against enzymatic degradation was confirmed in vivo. Of the radiopeptides studied, [111In]In-DOTA-[(N-Me)1Nal8]MGS5 showed the most promising targeting properties, with significantly increased accumulation of radioactivity in A431-CCK2R xenografts (48.1 ± 9.2% IA/g) and reduced accumulation of radioactivity in stomach (4.2 ± 0.5% IA/g). However, in comparison with DOTA-MGS5, a higher influence on the targeting properties was observed for the change of radiometal, resulting in a tumor uptake of 15.67 ± 2.21% IA/g for [68Ga]Ga-DOTA-[(N-Me)1Nal8]MGS5 and 35.13 ± 6.32% IA/g for [177Lu]Lu-DOTA-[(N-Me)1Nal8]MGS5.

Free energy landscape of wrapping of lipid nanocluster by polysaccharides

Wrapping of a 20-mer cholesterol nano-cluster (CHL-nanoC) by two widely different types of β-glucan polysaccharides (23–25 mers) having significantly varying glycosidic linkage patterns and side chains is studied by Well-Tempered MetaDynamics (WT-MetaD) simulations. The problem has its relevance in the faecal sterol and bile acid excretion in humans and the role of dietary fibres in aiding the process and combating dyslipidemia. Additionally, the distinctive collective variables studied here can be extended for modeling of polymer wrapped soft clusters/nano-particles in general. The wrapping ability is observed to be significantly correlated to the bending of the polysaccharide chain, an attribute of the glycosidic linkage type. By biasing two unique collective variables, the radius of gyration of the polysaccharide (Rg, poly) and the second order Legendre polynomial of the segment orientation parameter, θ, we could successfully observe the wrapping process. This work compares in detail the physical properties of the polysaccharide encapsulated CHL-nanoC by probing the radius of curvature (Rcurv, poly) of the polysaccharides, their coordination number with respect to the CHL-nanoC (CN), fractional CHL-nanoC surface coverage and the electrostatic surface potentials of the complex assembly. Results indicate that the β-glucan having 1–4 glycosidic linked monomers with intermittent 1–3 linkage is able to wrap the CHL-nanoC more effectively. The 1–3 glycosidic linked β-glucan with 1–6 glycosidic bonds in side chains is significantly curled up and appears to be less efficient in wrapping the nanoC. This work provides a comparative molecular level picture of mutual interaction between two major dietary polysaccharide variants and lipid globules as indicated by numerous clinical level studies involving mice and human models.

Co-pyrolytic performances, mechanisms, gases, oils, and chars of textile dyeing sludge and waste shared bike tires under varying conditions

The massive industrial wastes of textile dyeing sludge (TDS) and waste shared bike tires are becoming increasingly problematic environmentally and economically. Their co-pyrolysis maybe an affordable and eco-friendlier alternative so as to reduce their waste volumes and emissions, as well as recover value-added oils and chars. This study was the first to characterize the TDS co-pyrolysis with rubber (RT) versus polyurethane (PUT) tires and their performances, mechanisms, emissions, oils, and chars as a function of temperature and blend type and ratio. The co-pyrolysis increased the total weight loss from 51.76% with TDS to 55.30% with 50% TDS and 50% RT (TR55) and to 68.92% with TP55. TR55 and TP55 yielded the best performances, with the stronger synergistic effect with the TP than TR co-pyrolysis. The optimal reaction models were second-order (F2) and five-dimension diffusion (D5) for the two devolatilization sub-stages for TDS, two thirds-order (F1.5) for the TR55 and the second and fourth sub-stages of the TP55, and F2 for the first and third sub-stages of the TP55. The co-pyrolysis reduced emissions of CO, SO2, and nitrous compounds, did not change their temperature dependency, and produced more hydrocarbon products. The TR co-pyrolysis produced more D-limonene and isoprene and inhibited the isomerization of D-limonene. The TP co-pyrolysis further decomposed diaminodiphenylmethane into low-molecular weight benzene series such as toluene and styrene. The co-pyrolytic chars had higher branching degree of aliphatic side chain and bridge bond, with the TP ones having the enhanced char aromaticity.

The Influence of Polymer Composition on the Hydrolytic and Enzymatic Degradation of Polyesters and Their Block Copolymers with PDMAEMA.

Well-defined, semi-degradable polyester/polymethacrylate block copolymers, based on ε-caprolactone (CL), d,l-lactide (DLLA), glycolide (GA) and N,N′-dimethylaminoethyl methacrylate (DMAEMA), were synthesized by ring-opening polymerization (ROP) and atom transfer radical polymerization. Comprehensive degradation studies of poly(ε-caprolactone)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PCL-b-PDMAEMA) on hydrolytic degradation and enzymatic degradation were performed, and those results were compared with the corresponding aliphatic polyester (PCL). The solution pH did not affect the hydrolytic degradation rate of PCL (a 3% Mn loss after six weeks). The presence of a PDMAEMA component in the copolymer chain increased the hydrolysis rates and depended on the solution pH, as PCL-b-PDMAEMA degraded faster in an acidic environment (36% Mn loss determined) than in a slightly alkaline environment (27% Mn loss). Enzymatic degradation of PCL-b-PDMAEMA, poly(d,l-lactide)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PLA-b-PDMAEMA) and poly(lactide-co-glycolide-co-ε-caprolactone)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PLGC-b-PDMAEMA) and the corresponding aliphatic polyesters (PCL, PLA and PLGC) was performed by Novozyme 435. In enzymatic degradation, PLGC degraded almost completely after eleven days. For polyester-b-PDMAEMA copolymers, enzymatic degradation primarily involved the ester bonds in PDMAEMA side chains, and the rate of polyester degradation decreased with the increase in the chain length of PDMAEMA. Amphiphilic copolymers might be used for biomaterials with long-term or midterm applications such as nanoscale drug delivery systems with tunable degradation kinetics.

Deepening of lipidome annotation by associating cross-metathesis reaction with mass spectrometry: application to an in vitro model of corneal toxicity.

The in-depth knowledge of lipid biological functions needs a comprehensive structural annotation including a method to locate fatty acid unsaturations, which remains a thorny problem. For this purpose, we have associated Grubbs' cross-metathesis reaction and liquid chromatography hyphenated to tandem mass spectrometry to locate double bond positions in lipid species. The pretreatment of lipid-containing samples by Grubbs' catalyst and an appropriate alkene generates substituted lipids through cross-metathesis reaction under mild, chemoselective, and reproducible conditions. A systematic LC-MS/MS analysis of the reaction mixture allows locating unambiguously the double bonds in fatty acid side chains of phospholipids, glycerolipids, and sphingolipids. This method has been successfully applied at a nanomole scale to commercial standard mixtures consisting of 10 lipid subclasses as well as in lipid extracts of human corneal epithelial (HCE) cell line allowing to pinpoint double bond of more than 90 species. This method has also been useful to investigate the lipid homeostasis alteration in an in vitro model of corneal toxicity, i.e., HCE cells incubated with benzalkonium chloride. The association of cross-metathesis and tandem mass spectrometry appears suitable to locate double bond positions in lipids involved in relevant biological processes.

The interaction of rhodium compounds with proteins: A structural overview

• Structures of proteins containing Rh atoms have been summarized and described. • Structures of proteins containing Rh atoms reported in the PDB have been analyzed. • The effect of Rh binding on the protein structure has been discussed. • Main features of Rh binding sites in the structures of proteins containing Rh atoms have been highlighted. Rhodium compounds have been used as scaffold for enzyme inhibitors, modulators of protein/protein interactions and of protein aggregation. These compounds have been investigated in their reaction with peptides and proteins with the aim to create artificial metalloenzymes with enhanced catalytic features. Despite several studies have been carried out in this context, the interactions occurring between Rh compounds and these biological molecules and the mechanisms that are responsible for the formation of Rh/peptides and Rh/protein adducts are still largely unknown. This review describes and analyzes the known structures of complexes between protein and Rh compounds and of Rh/protein adducts deposited in the Protein Data Bank. Artificial metalloenzymes are frequently formed by anchoring Rh compounds to proteins via covalent linkage strategies. However, new biohybrids can also be formed by dative anchoring, since coordinative bonds of protein residue side chains with Rh centers (and non-covalent interactions between protein atoms and Rh ligands) can occur. In these adducts, Rh centers preferentially bind the side chains of His, Asp, Asn, Lys and the C-terminal carboxylate. Our analysis provides interesting implications for the design of Rh-based artificial metalloenzymes.

Biomineralization of Hydroxyethyl Cellulose/Sodium Alginate for Bone Tissue

The aim of this research is to synthesis biopolymeric materials from hydroxyethyl cellulose (HEC) (5 wt. %) blended with sodium alginate (SA) (10 wt. %) at 1:1 ratio fabricated by using freeze-drying technique. The HES/SA was treated with simulated body fluid (SBF) by immersion technique through the depositing of calcium phosphate on the scaffold’s surfaces. All scaffolds were characterizing by using field emission electron microscope (FESEM), attenuated total reflectance-Fourier infrared transform (ATR-FTIR), and thermogravimetric analysis (TGA). The FESEM images results displayed interconnected porous structure with diameter ranging from 40 to 400 μm with average apatite diameter in range of 95 nm – 148 nm. The ATR-FTIR results exhibit possible interactions between hydroxyl groups of HEC, SA and apatite groups of the scaffolds. The TGA results showed four different regions of mass losses, represents the amorphous transition temperature and water disposal, side-chain bond breaking, pyrolysis of SA and dihydroxylation behaviour of calcium phosphate, respectively. Cell-scaffolds interaction demonstrated that human fetal osteoblast (hFOB) cells differentiated and spread well on scaffolds with better cell proliferation and attachment was more prominent on HEC/SA treated with SBF. Since these biocompatible and biodegradable scaffolds showed promising results, these scaffolds could be adopted for the design of next-generation tissue-engineered bone grafts.

Disruption of the integrin-linked kinase (ILK) pseudokinase domain affects kidney development in mice

Disruption of the integrin-linked kinase (ILK) pseudokinase domain affects kidney development in mice

Side chain functional carbazole‐fluorene electroactive polymers: Optical, electrochemical properties, antimicrobial activity and thin film morphologies

AbstractA new electroactive polymer based on fluorene and carbazole moieties with double bond side chain (MP25) was synthesized and then double bond at the side chain was functionalized with COOH and Si(OEt)3 as ITO/glass compatible groups. Electrochemical and optical properties of the polymers were elucidated with cyclic voltammetry (CV), ultraviolet–visible absorption (UV–Vis), and photoluminescence (PL) spectroscopy. It was observed that all polymers absorbed only the UV region and emitted blue light. By using CV, HOMO values were found as approximately 5.45 eV. According to AFM results, when the rough MP25 polymer thin film was modified with ITO/glass compatible groups, more uniform and smoother polymer thin films were obtained. Thermogravimetry analyses (TGA) shown that the MP25‐Si and MP25‐COOH were stable against thermo‐oxidative decomposition. The weight loss of MP‐25‐Si was found to be only %23 at 700°C. Additionally, antimicrobial activity of MP25 polymers was also investigated. According to test results, all polymers were found to have antimicrobial activity against C.albicans.

An ultraviolet-assisted electrospinning procedure of polyimide ultrafine fibrous membranes fabricated by ester-type negative photosensitive polyimide

An ultraviolet-assisted electrospinning (UVAES) procedure was performed using in situ photopolymerization during the electrospinning process to enhance the solvent resistance of polyimide (PI) ultrafine fibrous membranes (UFMs). The resultant PI UFMs were fabricated via solution electrospinning using photosensitive poly(amic acid ester) (PSPAE) modified with unsaturated double bond side chains as the main fiber-forming agent, diethylene glycol diacrylate as the crosslinker, and titanocene as the photoinitiator. The precursor PSPAE UFMs were prepared via both of normal electrospinning and UVAES procedures and then were converted to PI using thermal imidization at 350 °C in a nitrogen imidization. The physical and chemical properties of the obtained PI UFMs were subsequently studied. The fibers exposed to ultraviolet irradiation possessed a smooth surface morphology and maintained their fibrous structure after thermal imidization at elevated temperature as high as 350 °C in nitrogen, whereas the crosslink-free PSPAE fibers lost their fibrous structure after heating. Furthermore, as well as providing enhanced thermal decomposition stability, the introduction of a crosslinked structure via ultraviolet irradiation also protected the molecular chains from organic solvents, resulting in excellent solvent resistance of the PI UFMs.

A-D-A Type Semiconducting Small Molecules with Bis(alkylsulfanyl)methylene Substituents and Control of Charge Polarity for Organic Field-Effect Transistors.

In this study, we synthesize four different kinds of bis(alkylsulfanyl)methylene-substituted 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene (IDT)-based acceptor-donor-acceptor (A-D-A) type small molecules (IDSIC, IDSIC-4F, IDSIC-4Cl, and IDSTIC) by incorporating electron-withdrawing halogen atoms or electron-releasing thiophene spacers. Herein, enhanced structural planarity and crystalline intermolecular packing are induced by the sp2-hybridized C═C double bond side chains and sulfur-sulfur chalcogen interactions. The fine control of intramolecular charge transfer modulates the electrochemical characteristics and the resulting carrier polarity in organic field-effect transistors (OFETs). Well-balanced ambipolar, n-dominant, and p-dominant charge transport properties are successfully demonstrated in OFETs by modulating the electron-donating or withdrawing strength based on the A-D-A structural motif, resulting in hole/electron mobilities of 0.599/0.553, 0.003/0.019, 0.092/0.897, and 0.683/0.103 cm2/V·s for IDSIC, IDSIC-4F, IDSIC-4Cl, and IDSTIC respectively, after thermal annealing at 200 °C. Thermal annealing of the as-cast films improves the intermolecular packing in an edge-on fashion, which is investigated in detail by grazing incidence X-ray scattering. Finally, complementary logic circuits, i.e., NOT, NAND, and NOR, are fabricated by assembling p-dominant IDSTIC and n-dominant IDSIC-4Cl OFETs. Therefore, a simple and efficient molecular design strategy for fine tuning the charge polarity and charge transport properties of OFET devices is presented.

Construction of Cyclophane-Braced Peptide Macrocycles via Palladium-Catalyzed Picolinamide-Directed Intramolecular C(sp2)-H Arylation.

A versatile method for the construction of C(sp2)-linked cyclophane peptide macrocycles via Pd-catalyzed picolinamide-directed intramolecular arylation of aryl and alkenyl C-H bonds of amino acid side chains with aryl iodides is developed. This method provides simple and efficient access to a variety of cyclophane-braced structures from readily accessible linear peptide precursors.