Introduction Of Side Chains Research Articles

Current Status and Applications of Gamma Radiation-induced Graft Copolymerized Chitosan

Chitosan (CS) is a natural polymer obtained by removing acetyl groups from chitin through alkaline hydrolysis. It possesses biodegradable properties and exhibits immunological, antibacterial, and wound-healing activities. This polysaccharide has undergone modification through radiation-induced graft copolymerization to broaden its application scope. The potential applications of CS can be expanded by introducing side chains through grafting. This article aims to review the innovative alternatives of gamma-graft-copolymerized CS and, for the first time, comprehensively examines the current applications of CS derivatives in dye removal, metal adsorption, antibacterial interventions, biomedical practices, drug delivery systems, and tissue engineering.

Towards Tailored Dialdehyde Cellulose Derivatives: A Strategy for Tuning the Glass Transition Temperature.

The derivatization of dialdehyde cellulose (DAC) has received increasing attention in the development of sustainable thermoplastics. In this study, a series of dialcohol celluloses were generated by borohydride reduction, which exhibited glass transition temperature (Tg ) values ranging from 23 to 109 °C, depending on the initial degree of oxidation (DO) of the DAC intermediate. However, the DAC derivatives did not exhibit thermoplastic behavior when the DO of the modified DAC was below 26 %. The influence of introduced side chains was highlighted by comparing DAC-based thermoplastic materials obtained by either oximation or borohydride reduction. Our results provide insights into the generation of DAC-based thermoplastics and highlight a strategy for tailoring the Tg by adjusting the DO during the periodate oxidation step and selecting appropriate substituents in subsequent modifications.

Unveiling the adsorption and inhibition mechanism of thiadiazole derivatives for mild steel corrosion in hydrochloric acid based on experimental approaches and first-principles calculations

In this work, two eco-friendly thiadiazole derivatives, 5-amino-1,2,3-thiadiazole (AT) and N-phenyl-N-1,2,3-thiadiazol-5-yluree (thidiazuron, TDZ), were employed to alleviate the corrosion of mild steel in hydrochloric acid medium. Electrochemical tests show that compared to AT, TDZ exhibits a much better inhibitive effect with an inhibition efficiency of 98.95% at 0.6 mM. The introduced side chain with phenyl ring in TDZ molecule endues it with more adsorption sites, which facilitates the strong absorption of TDZ by the extra bonding of O atom and phenyl ring with steel surface. The DFT-based first-principles calculations indicate that AT and TDZ could adsorb on the steel surface through the thiadiazole ring, O atom and phenyl ring by forming Fe–S, Fe–N, Fe–O, and Fe–C bonds. The parallel adsorptions of AT and TDZ are more stable with more negative adsorption energy than their perpendicular adsorptions. Furthermore, the non-covalent interaction between AT/TDZ and H2O solvent molecules deteriorates their adsorptions on steel surface.

Reducing the dielectric loss of poly(aryl ether)s by grafting

AbstractLimiting molecules' polarized motion effectively reduces the dielectric loss of materials. This article synthesized side chains with different lengths using p‐ethoxyphenol, p‐hydroxybenzoic acid, and long‐chain halohydrins through a two‐step process. These chains' movement was almost unaffected by the main chain of polymers, so they can fill up the free volume of polymers under certain conditions. 1,2‐dihydro‐4‐(4‐hydroxyphenyl)phthalazine‐1‐(2H)‐one(DHPZ), 4,4'‐Difluorophenyl sulfone(DFS), and 4,4‐Bis(4‐hydroxyphenyl) valeric acid(HPV) obtained three polymers with different carboxyl groups (10%, 30%, and 50%) through nucleophilic substitution. They were then grafted and treated with hot‐pressing. The introduction of side chains could reduce the free volume of polymers under hot‐pressing conditions, so further reducing the dielectric loss of materials. Polymer with the shortest and least (10%) side chains showed the most obvious dielectric loss tangent, the reduction rate of the film's dielectric loss tangent was 13.11% (at Tg + 15°C, while the non‐grafted one was only 3.69%) and 20.70% (at Tg + 80°C, while the non‐grafted one was only 8.35%), respectively. In addition, WXRD and DMA tests showed that films' intermolecular chain spacing (“d”) and Tg changed after the hot‐pressing process, respectively. The change law of both was consistent with that of dielectric loss tangent. Confirm that grafting high‐motility side chains can significantly reduce polymer's dielectric loss by enhancing the free volume reduction effect after hot‐pressing.

Novel p.G250A Mutation Associated with Chronic Pancreatitis Highlights Misfolding-Prone Region in Carboxypeptidase A1 (CPA1).

Inborn mutations in the digestive protease carboxypeptidase A1 (CPA1) gene may be associated with hereditary and idiopathic chronic pancreatitis (CP). Pathogenic mutations, such as p.N256K, cause intracellular retention and reduced secretion of CPA1, accompanied by endoplasmic reticulum (ER) stress, suggesting that mutation-induced misfolding underlies the phenotype. Here, we report the novel p.G250A CPA1 mutation found in a young patient with CP. Functional properties of the p.G250A mutation were identical to those of the p.N256K mutation, confirming its pathogenic nature. We noted that both mutations are in a catalytically important loop of CPA1 that is stabilized by the Cys248-Cys271 disulfide bond. Mutation of either or both Cys residues to Ala resulted in misfolding, as judged by the loss of CPA1 secretion and intracellular retention. We re-analyzed seven previously reported CPA1 mutations that affect this loop and found that all exhibited reduced secretion and caused ER stress of varying degrees. The magnitude of ER stress was proportional to the secretion defect. Replacing the naturally occurring mutations with Ala (e.g., p.V251A for p.V251M) restored secretion, with the notable exception of p.N256A. We conclude that the disulfide-stabilized loop of CPA1 is prone to mutation-induced misfolding, in most cases due to the disruptive nature of the newly introduced side chain. We propose that disease-causing CPA1 mutations exhibit abolished or markedly reduced secretion with pronounced ER stress, whereas CPA1 mutations with milder misfolding phenotypes may be associated with lower disease risk or may not be pathogenic at all.

Enhancing side chain swing ability by novel all-carbon twisted backbone for high performance anion exchange membrane at relatively low IEC level

A novel all-carbon backbone-based membrane is designed by introducing side chains at the non-coplanar site of twisted “ether-free” main chain via Suzuki coupling reaction. The twisted backbone reduces the hindrance effect, providing broader mobile space for the side chains and enhancing the swing ability of the side chains to facilitate the formation of ion channels and the transportation of OH−. As a result, the high conductivity is obtained at a relatively low IEC level. The QPS-PB-4 membrane exhibits a superior OH− conductivity of 50.1 to 94.4 mS cm−1 at 30 ℃ to 80 ℃ with an IEC of only 1.48 mmol g−1, and a low swelling ratio of less than 10%. Which show significant advantage among the traditional side-chain-type AEMs reported in recent years. Moreover, the as-prepared membranes have good mechanical and thermal stability, as well as excellent chemical stability because of the all-carbon backbone designed without any sensitive sites that can be attacked by hydroxide. The conductivity of the QPS-PB-4 membrane decrease by only 8% after treatment at 80 ℃ in 1 M NaOH for 1800 h. The fuel cell assembled with the as-prepared membrane has a peak power density of up to 558.8 mW cm−², indicating the promising application potential of the membranes.

Insight into the mechanism of asphaltene disaggregation by alkylated treatment: An experimental and theoretical investigation

Mechanism of asphaltene disaggregation by alkylated treatment was revealed experimentally and theoretically. Significant increases both in inter-sheet distance and critical aggregation concentration were clearly observed after alkylation reaction of asphaltenes, indicating that alkylated treatment could well disaggregate asphaltenes and retard them reaggregating, further confirmed by molecular dynamics (MD) simulations. MD results indicate that grafting side-chains with moderate chain lengths, introducing isoalkyl side-chains with larger steric hindrance, or increasing the number of grafted side-chains, is more readily to achieve better disaggregation effect on asphaltene aggregate. Furthermore, a series of non-covalent interactions (NCIs) analyses was performed to elucidate diverse driving forces for disaggregating asphaltenes. Especially via the van der Waals potential analysis, newly developed in recent years, it was found that aside from enhancing exchange-repulsion, the introduction of side-chains brings additional dispersion attraction orthogonal to π-π stacking, thus disrupting the regularity of accumulation of asphaltenes; moreover, through averaged reduced density gradient (aRDG) analysis and adjuvant MD simulations, the role of solvents in affecting the disaggregation behavior was elucidated. This research provides an effective method to disaggregate asphaltenes and contributes to solving the problems caused by asphaltenes aggregation.

Gelation of a Pentapeptide in Alcohols.

Properties of solvents such as polarity and H-bond-forming ability are critical for the formation of an organogel and have a significant impact on the gel behavior, as solvents are the majority of organogel systems. However, so far, there is still a lack of systematic studies regarding the effects of molecular structures of solvents on the characteristics of organogels. Motivated by revealing such a relationship, in this paper, we studied the morphologies of assemblies, gelation behaviors, and secondary structures of a pentapeptide termed EAF-5 in a wide variety of alcohols. The side chains and lengths of carbon chains of the solvent molecules were found to play a critical role in the self-assembly and gelation of EAF-5. EAF-5 was capable of self-assembling into fibers and entangling into a network in alcohols including ethanol, propanol, butanol, n-pentanol, and n-hexanol, which further immobilized the corresponding alcohols to form gels. In these organogels, increasing β-sheet secondary structures of the peptides were formed by introducing side chains and extending the length of primary alcohol molecules. We hypothesized that alcohol molecules with extended lengths and side chains reduced the gelator-solvent interactions and promoted the gelator-gelator interactions, resulting in the self-assembly of EAF-5 into fibril structures and development of gels. These findings provide a new sight into the interactions between gelators and solvents and are helpful for designing peptide-based organogelators.

Synthesis and performance of flexible epoxy resin with long alkyl side chains via click reaction

AbstractEpoxy resin is a thermosetting polymer with excellent performance and wide application. However, it suffers from low toughness and high brittleness because of its high crosslink density. To overcome these disadvantages, this study synthesizes a toughened, flexible, and hydrophobic epoxy resin (DGEBDBP) by introducing a flexible segment into the polymer network via a thiol‐ene click reaction. The cured flexible epoxy resin is obtained by mixing E44, DGEBDBP, and polyamide curing agents of varying contents. The long alkyl side chains significantly improve the mechanical properties and hydrophobicity of the cured epoxy resin. The sample containing 75% DGEBDBP and 25% E44 achieve the highest breaking elongation that was nine times that of pure E44, the highest compressive strength of 112.8 MPa, and the highest contact angle of 101.4°. The introduction of side chains through the thiol‐ene click reaction can provide a simple and effective method for designing and preparing multifunctional epoxy resins.

Study on the Characteristics of Photovoltaic and Field Effect of Small Molecule Donors

Two benzothiadiazole (BT) small molecule donors (namely D1 and D2) were designed and synthesized. We studied their photovoltaics properties and filed effect properties. It is found that the best power conversion efficiency (PCE) of the organic solar cells (OSCs) was 6.87% based on the D2: IDIC-4F (the donor/acceptor(D/A) ratio is 1:1). In contrast, the device of D1: IDIC-4F (the D/A ratio is 1:1) only shows PCE value of 2.41%. This is because that the crystallization property of the material is improved by the changing of side chain group, which is beneficial to the improvement of the morphology of the donor material. Moreover, the introduction of side chain greatly improves the external quantum efficiency (EQE) of D2 based solar cell. Also, we fabricated the organic field effect transistors (OFETs) with D1 and D2 as semiconductor layer, and n-octadecylphosphonic acid (ODPA) as self-assembled monolayers (SAMs), as a result, the hole motilities of the devices are ${1.21}\times {10} ^{-{2}}$ cm $^{{2}}\text{v}^{-{1}}\text{s}^{-{1}}$ for D1 and ${1.25}\times {10} ^{-{2}}$ cm $^{{2}}\text{v}^{-{1}}\text{s}^{-{1}}$ for D2, respectively.

Low-Modulus Elastomeric Matrices for Magnetoactive Composites with a High Magnetic Field Response

Magnetoactive elastomers based on polydimethylsiloxane functional oligomers with a concentration of magnetic iron microparticles of 70, 75, and 80 wt % are synthesized. Soft samples with low (about 2 kPa) elastic moduli are obtained by introducing side chains into the polymer network without using a low molecular weight oil. It is shown that the rigidity of the matrix can be controlled by varying the concentration of only the crosslinking agent. The obtained magnetoactive elastomers have a high magnetic field response: the relative growth of the real part of the dynamic shear modulus of soft samples exceeds two orders of magnitude and reaches 400 in a magnetic field of 1 T. The contact angle of water with the surface of the composites increases to 140° in a magnetic field of the order of 400 mT.

Electrochromic polymers with multiple redox couples applied to monitor energy storage states of supercapacitors.

Two electrochromic polymers based on thiophene-benzene derivatives were prepared using an electrochemical method and exhibited multiple separate redox couples due to the introduction of side chains. The energy storage states of electrochromic supercapacitors based on the resulting polymers could be monitored by their appearance colour.

N-Type Thin-Film Transistors Based on Diketopyrrolopyrrole Derivatives: Role of Siloxane Side Chains and Electron-Withdrawing Substituents.

The physical properties, packing, morphology, and semiconducting performance of a planar π-conjugated system can be effectively modified by introducing side chains and substituent groups, both of which can be complementary to the π framework in changing the intermolecular association, frontier molecular orbital energy, optical band gap, and others. We herein show that installation of end-capped electron-withdrawing groups (EWGs), such as dicyanovinyl (-DCV), 3-ethylrhodanine (-RD), and 2-(3-oxo-indan-1-ylidene)-malononitrile (-INCN), together with siloxane side chains to the backbones of dithienyldiketopyrrolopyrrole (DPPT), such as DPPT-Si-DCV, DPPT-Si-RD, and DPPT-Si-INCN, can greatly improve its solubility, air stability, and film morphology to serve as an n-channel in thin-film transistor fabrication. The EWGs attached to the DPPT core narrowed the optical band gap (Egopt) and changed the highest occupied molecular orbital and the lowest unoccupied molecular orbital energies (EHOMO and ELUMO), making them suitable for n-channel field-effect transistor (FET) applications. The benefits of introducing siloxane side chains to the DPPT core include enhanced solubility, low crystallization barrier, enantiotropic phase behavior, and much improved FET performance. The DPPT-Si-INCN film displayed low-lying HOMO (-5.82 eV) and LUMO (-4.60 eV) energy levels and an optical band gap as low as 1.22 eV, all of which suggest that this derivative can be quite resistant toward aerial oxidation. Thin films of these derivatives were prepared by the solution-shear method. A comparison of the solution-sheared films indicated that the molecular packing motif of DPPT-Si-INCN film was somehow different from that of DPPT-Si-DCV and DPPT-Si-RD, in which the π-π stacking tended to align orthogonally to the shearing direction. This specific π-π stacking alignment could have an impact on the electron mobility (μe) values in transistors based on the solution-sheared films.

Preparation of multifunctional glycopolymers using double orthogonal reactions and the effect of electrostatic groups on the glycopolymer–lectin interaction

We investigated synthetic biomacromolecules to control molecular interactions. Multifunctional glycopolymers for molecular recognition were prepared via living radical polymerization and post-click chemistry with orthogonal Huisgen and thiol-epoxy reactions. The synthesis of the polymer backbone and the subsequent side-chain introduction successfully proceeded in high yield. The multifunctional glycopolymers had a tri-block structure: the first and third blocks contained mannose, and the second block contained either a positively or negatively charged group or a neutral hydrophilic group. The molecular recognition of the glycopolymers toward lectin was evaluated via fluorescence quenching measurements. Because of the electrostatic interaction, the binding constant varied in the following order: positively charged glycopolymer (PT110) > negatively charged glycopolymer (NT110). The effect of the electrostatic interactions was modest compared with the effect of the carbohydrate–lectin binding. These results suggested that the carbohydrate–lectin interaction was an important factor in the molecular recognition of glycopolymers. This study provides guidelines for the preparation of multifunctional polymers, such as biomaterials. The block glycopolymers with specific arrangement of sugar ligand and electric charges were synthesized via RAFT living radical polymerization, where the block polymers were efficiently obtained using two orthogonal reactions of Huisgen and thiol-epoxy ring opening reactions. The molecular recognition abilities of the block glycopolymers was examined.

Synthesis of Para (-)-Δ8-THC Triflate as a Building Block for the Preparation of THC Derivatives Bearing Different Side Chains.

A two-step synthesis of para (-)-Δ8-THC-OTf that can be used as building block for late-stage introduction of side chains to the tetrahydrodibenzopyran core of THC by cross-coupling chemistry is presented. No protecting groups are needed, and (-)-Δ8-THC-OTf can be cross-coupled to access derivatives bearing pharmacologically interesting side chains such as benzoyl units, sterically demanding groups, aromatic chains, and alkenyl groups. This approach allowed an efficient four-step synthesis of (-)-Δ8-THC from commercial materials.

Synthesis of 3β-tert-Butyldimethylsiloxy-22-phenylthio-23,24-bisnorchola-5,9(11)-diene and Reductive Nucleophilic Attack on a Branched Aliphatic Aldehyde.

3β-tert-Butyldimethylsiloxy-22-phenylthio-23,24-bisnorchola-5,9(11)-diene, which has a double bond between C-9 and C-11 and a phenylsulfenyl group on the terminus of the side chain, is a potential synthetic intermediate for steroids with 9,11-unsaturation or 9,11-seco skeletons. We describe here the synthesis of the title compound from 17-ethylenedioxy-3-acetoxyandrosta-3,5-dien-11-one. The introduction of an ethylene unit to 3β-tert-butyldimethylsiloxyandrosta-5,9(11)-dien-17-one by the action of ethyltriphenylphosphonium bromide under basic conditions resulted in an inseparable mixture of two stereoisomeric products (5 : 1). However, in the subsequent step, only the (Z)-isomer was susceptible to the Lewis acid-catalyzed ene reaction with formaldehyde, giving a stereochemically pure product with the desired configuration. Within three steps, the ene-product was derivatized to the title compound, with a total yield of 53% over seven steps. Reductive terminal anion formation by treatment with lithium di-tert-butylbiphenyl (LiDBB) and subsequent nucleophilic attack on a branched aliphatic aldehyde was demonstrated, with an eye toward the introduction of side chains, especially for steroids with oxygen functionality at C-23.

Effect of chemical structure and deposition method on optical properties of polyazomethines with alkyloxy side groups

Three (two novel) conjugated, thiophene phenylene based polyazomethines have been obtained parallel, by chemical vapour deposition (CVD) and by chemical synthesis. They were subsequently identified and characterised by an X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry and detailed UV–Vis-NIR spectroscopy. Absorption spectra of the polymers' solutions and thin films have been examined. The spectra of polyazomethines without, with methoxy and with octyloxy side chains attached to the polymer backbone showed a conjugation-improving effect of alkyloxy side chain introduction. A comparison of spectra of the same polyazomethine's thin films deposited separately by spin-on and CVD methods revealed decrease in conjugation of compounds obtained during CVD. Additionally, amorphous character of the investigated thin films allowed to calculate the absorption edge parameters, in a way typical for amorphous semiconductor and to discuss their values in the context of chemical structure and deposition method. Surface imaging with atomic force microscope revealed different character of thin films deposited by spin-on and CVD methods.

Quantitative investigations of xylose and arabinose substituents in hydroxypropylated and hydroxyvinylethylated arabinoxylans

The chemical structures obtained by the modification of arabinoxylans with the cyclic carbonates propylene carbonate (PC) and 4‐vinyl-1,3-dioxolan-2-one (VEC) with varying degrees of substitution were investigated. Therefore, a new analytical method was developed that is based on a microwave-assisted hydrolysis of the polysaccharides with trifluoroacetic acid and the reductive amination with 2-aminobenzoic acid. The peak assignment was achieved by HPLC–MS and the carbohydrate derivatives were quantified by HPLC-fluorescence. The obtained maximum molar substitution of PC-derivatized xylan (XHP) was 1.8; the molar substitution of VEC-derivatized xylan (XHVE) was 2.3. Investigations of xylose and arabinose based mono- and disubstituted derivatives revealed a preferred reaction of the cyclic carbonates with arabinose. Conversion rates were up to 2.4 times higher for monosubstitution and up to 3.0 times for disubstitution compared to xylose. Furthermore, the reaction with VEC was preferred due to higher reactivity of the newly introduced side chains.

Side-Chain Influence of Wide-Bandgap Copolymers Based on Naphtho[1,2-b:5,6-b]bispyrazine and Benzo[1,2-b:4,5-b']dithiophene for Efficient Photovoltaic Applications.

In this work, we reported new types of wide-bandgap copolymers, PBDTA-NPz, PBDTT-NPz, PBDTF-NPz, and PBDTP-NPz, on the basis of the naphtho[1,2-b:5,6-b]bispyrazine (NPz) acceptor building block for efficient photovoltaic applications. The influencing factors of the introduced side chains, including alkoxyl, alkylthienyl, alkylfuryl, and alkoxylphenyl, were investigated in detail. These copolymers possessed wide bandgaps ranging from 1.79 to 1.88 eV with different nonconjugated or conjugated side chains. They also possessed deep highest-occupied molecular orbital levels of less than -5.25 eV, which allowed the achievement of high Voc's from their polymer solar cells (PSCs). The X-ray diffraction results indicated their excellent crystallinity and molecular stacking features, especially for PBDTF-NPz containing alkylfuryl side chains. Their photovoltaic performances were measured using bulk-heterojunction single-junction PSCs with a configuration of ITO/PEDOT:PSS/copolymer:PC71BM/Ca/Al under the same processing conditions. Different side chains of NPz-based copolymers induced largely different device performances. Without the additive, 1,8-diiodooctane (DIO), the primary PBDTA-NPz, PBDTT-NPz, PBDTF-NPz, and PBDTP-NPz devices showed power conversion efficiencies (PCEs) of 4.53, 6.09, 7.06, and 3.49%, respectively. On adding 3 vol % DIO, the device performances were elevated to a higher level. The PBDTF-NPz devices exhibited the highest PCE of 8.63%, which resulted in improved Voc, Jsc, and FF values caused by their inherent properties. Our results indicated that NPz is a potential acceptor unit to construct high-powered wide-bandgap copolymers for efficient PSCs in the future.

Identification of Residues Important for Ion and Lipid Transport in a TMEM16 Scramblase

The TMEM16 family comprises Ca2+-activated Cl- channels and phospholipid scramblases. The recent crystal structure of a fungal homologue, nhTMEM16, revealed an important architectural feature of this protein family in the form of a bilayer-spanning hydrophilic groove that is directly exposed to the membrane and provides a possible pathway for lipid translocation. Mutations that alter ion channel activity of the TMEM16 proteins localize around the groove, suggesting that the ion and lipid pathways coincide. However, an initial report suggested that nhTMEM16, unlike other TMEM16 scramblases, does not mediate ion transport. Here, we show that nhTMEM16 mediates simultaneous ion and lipid transport and that its properties closely resemble those of afTMEM16.To test the hypothesis the hydrophilic groove forms a shared pathway for ions and lipids we mutated residues facing the groove to tryptophan (Trp), as its bulky and hydrophobic side chain should impair transport. We then investigated how these mutations affect scrambling and ion transport. Of the 17 Trp-mutants tested, 40% had little to no effect on scrambling ( 50% reduction). Interestingly, the impact on ion transport closely mirrored that on scrambling, consistent with the idea that these two functions are tightly coupled. We identify a set of 3 residues which define a constriction in the groove, which when mutated to Trp cause a dramatic reduction in the rate of scrambling. Unexpectedly however, this effect is independent of the size of the introduced side chain as mutations to Alanine (Ala) has a comparably adverse impact on scrambling. Taken together our results indicate that the specific chemico-physical properties of these 3 residues lining the groove is crucial to lipid and ion transport of nhTMEM16.