S Bond Research Articles

Arylthianthrenium Salts for Triplet Energy Transfer Catalysis.

Sigma bond cleavage through electronically excited states allows synthetically useful transformations with two radical species. Direct excitation of simple aryl halides to form both aryl and halogen radicals necessitates UV-C light, so undesired side reactions are often observed and specific equipment is required. Moreover, only aryl halides with extended π systems and comparatively low triplet energy are applicable to synthetically useful energy transfer catalysis. Here we show the conceptual advantages of arylthianthrenium salts (ArTTs) for energy transfer catalysis with high energy efficiency compared to conventional aryl (pseudo)halides and their utility in arylation reactions of ethylene. The fundamental advance is enabled by the low triplet energy of ArTTs that may originate in large part from the electronic interplay between the distinct sulfur atoms in the tricyclic thianthrene scaffold, which is not accessible in either simple (pseudo)halides or other conventional sulfonium salts.

Properties of Wedge Wire Bonded Connection Between a Composite Copper Core Aluminum Shell Wire and an 18650 Cylindrical Lithium-Ion Battery Cell.

Wedge wire bonding is a solid-state joining process that uses ultrasonic vibrations in combination with compression of the materials to establish an electrical connection. In the battery industry, this process is used to interconnect cylindrical battery cells due to its ease of implementation, high flexibility and ease of automation. Wire materials typically used in battery pack manufacturing are pure or alloyed aluminum and copper. While copper wires possess better electrical properties, the force used in the bonding process can lead to cell isolator damage and cell thermal runaway. This is an unacceptable result of the bonding process and has led to the development of new types of composite wires containing a copper core embedded in an aluminum shell. This material has the advantage of high copper electrical and thermal conductivity combined with less aggressive bonding parameters of the aluminum wire. The aim of this study was to establish a process window for the wedge wire bonding of 400 µm composite copper-aluminum Heraeus CucorAl Plus wire on the surface of a BAK 18650 battery cell. This study was conducted using a Hesse Bondjet BJ985 CNC wire bonder fitted with an RBK03 bond head designed for the bonding of copper wires. The methods used in this study included light and scanning electron microscopy of bond and battery cell cross-sections, shear testing on the XYZtec Sigma bond tester system, and energy dispersive spectroscopy. The results were compared with a previous study conducted using a wire of the same diameter and made out of high-purity aluminum.

Lattice defects and surface adsorption properties of gold-bearing chalcopyrite: A theoretical study based on DFT

Chalcopyrite (CuFeS2), as one of the carrier minerals of gold, undergoes significant alterations in lattice and surface properties upon doping with gold impurities. These changes markedly influence its separation and purification techniques, especially flotation. Using Density Functional Theory (DFT) based on first-principles, we analyze the influence of gold impurities on the lattice defects and surface properties of chalcopyrite. We developed an adsorption model using prop-2-yn-1-yl diethylcarbamodithioate (PDEC), a sulfur ester collector with an ethynyl group, on gold-infused chalcopyrite to elucidate the adsorption mechanism. Our findings indicate that the Au atom primarily occupies interstitial sites within the chalcopyrite lattice, resulting in an expanded lattice structure. Despite the doping, the lattice remains a p-type semiconductor with increased conductivity, facilitated by Au 6 s orbitals contributing to impurity levels within the conduction band from 2 to 4 eV. Additionally, there is a marked rise in spin-up electrons, with Integrated |Spin Density| results showing greater electron localization in Cu15Fe16S32Au and Cu16Fe16S32Au compared to ideal chalcopyrite crystal (Cu16Fe16S32). The Au atom exhibits maximum stability when adsorbed onto the S-Fe bonds on chalcopyrite surfaces, primarily forming covalent bonds through electron acceptance from Fe 3d orbitals. The presence of gold impurities decreases the collector's adsorption energy on the chalcopyrite (112) surface. However, PDEC exhibits enhanced adsorption performance relative to Al-DECDT and Z-200, primarily due to the chelation between thiocarbonyl and ethynyl groups of PDEC and the gold-bearing chalcopyrite (112) surface. Electron donation from Fe 4p orbitals of surface to the S 3 s and 3p orbitals of collector forms a sigma bond, while the ethynyl group undergoes hybridization with the Au 5d orbitals from −5 to −2.5 eV, fostering stable electron transfer.

Transition from synchronous to asynchronous mechanisms in 1,3-dipolar cycloadditions: a polarizability perspective.

This study investigates the energetic and polarizability characteristics of three 1,3-dipolar cycloaddition reactions between diazene oxide and substituted ethylenes, focusing on the transition from synchronous to asynchronous mechanisms. Synchronicity analysis, using the reaction force constant, indicates that the bond evolution process becomes increasingly decoupled as the number of cyano groups increases. Polarizability analysis reveals that isotropic polarizability reaches its maximum near the transition state in all cases, while anisotropy of polarizability shifts from the transition state toward the product direction as asynchronicity increases. The larger the shift, the more asynchronous the mechanism, as reflected by the weight of the transition region. A detailed examination of the parallel and perpendicular polarizability components to the newly formed sigma bonds shows that the evolution of the parallel component is closely aligned with the energetic changes along the reaction coordinate, particularly in the synchronous reaction. We have also identified a relationship between the displacement in the maximum state of the parallel component from the transition state and the synchronicity of the mechanism. The larger the displacement, the more asynchronous the mechanism. These findings suggest that asynchronous 1,3-dipolar cycloaddition mechanisms are characterized by a decoupling of isotropic and anisotropic polarizabilities and a shift in the maximum polarizability state of the parallel component toward the product direction. Density functional theory calculations were performed at the B3LYP/6-311 + + G(d,p)//B3LYP/6-31G(d,p) level of theory. The polarizability was calculated at each point of the reaction path, obtained using the intrinsic reaction coordinate method, as implemented in Gaussian 16.

Lithiophilic Polymers of High Conjugation and Mesoporosity Enable Lean and Dendrite-Free Lithium Anode.

Lithiated Cu current collectors with a lean Li supply have been extensively explored as prospective composite anodes for constructing lithium metal batteries (LMBs) but suffer from low Coulombic efficiencies (CE) and uncontrollable dendrite growth. Herein, two hexaazanonaphthalene (HATN)-based compounds comprising rich conjugated aromatic rings and redox-active C═N groups are synthesized and exploited to modify the Cu surface for mediating smooth Li plating/stripping. Compared to the HATN compound interlinked through flexible sigma bonds, the one conjugated through dual sp2-carbon manifests a more rigid backbone, improved electric conductivity, and enhanced mesoporosity. As a result, Cu electrodes modified with the latter demonstrate enhanced CE and suppressed dendrites in both half and symmetric cells, apart from a stable operation over 250 cycles in the LiFePO4 full cells with a capacity retention of 94.9% at 1 C. This study signifies the tailoring of intramolecular conjugation and chain configuration of lithiophilic macromolecules to facilitate reversible Li deposition on Cu for achieving high-performance LMBs.

A molecular ground electronic state with an occupied 5g spinor-The superheavy (E125)F molecule.

Fully relativistic calculations, primarily at the 4-component coupled-cluster singles and doubles with perturbative triples [CCSD(T)] level of theory with the Dirac-Coulomb (DC) Hamiltonian, have been carried out for the superheavy (E125)F molecule using large Gaussian basis sets. The electronic ground state is determined to have an [Og]8s25g16f3 configuration on E125 with an Ω = 6 ground state and an 8p electron largely donated to F. A Mulliken population analysis indicates that the ground state is mainly ionic with a partial charge of +0.79 on E125 and a single sigma bond involving the F 2p and E125 8p spinors. The occupied g spinor is not involved in the bonding. With the largest basis set used in this work, the (0K) dissociation energy was calculated at the DC-CCSD(T) level of theory to be 7.02eV. Analogous calculations were also carried out for the E125 atom, both the neutral and its cation. The lowest energy electron configuration of E125+, [Og]8s1/225g7/216f5/23 with a J = 6 ground state, was found to be similar to that in (E125)F, while the neutral E125 atom has an [Og]8s1/225g7/216f5/227d3/218p1/21 ground state electron configuration with a J = 17/2 ground state. The ionization energy (IE) of E125 is reported for the first time and is calculated to be 4.70eV at the DC-CCSD(T) level of theory. Non-relativistic calculations were also carried out on the E125 atom and the (E125)F molecule. The non-relativistic ground state of the E125 atom was calculated to have a 5g5 ground state with an IE of just 3.4eV. The net effect of relativity on (E125)F is to stabilize its bonding.

Synthesis, experimental and theoretical spectra, electronic and medicinal properties of 3-(3-(4-chlorophenyl)-1-phenyl-1H-pyrazol-4-yl)-5-ethoxy-4H-1,2,4-triazole

In this work, 3-(3-(4-Chlorophenyl)-1-phenyl-1H-pyrazol-4-yl)-5-ethoxy-4H-1,2,4-triazole compound has been synthesized and experimentally (FT-IR and 1H and 13CNMR) evaluated. .Density Functional Theory (DFT) is applied to investigate solvent solutes using a variety of solvents. The computed frequencies have been scaled. In global reactive parameters solvents significantly altered the molecule's characteristics behaviour, gas and water has high electrophilicity index which trigger its biological activity. The description focuses on how electron fragments influence the stimulation of electron states. From p*(C23-C24) to p*(C20-C25) and p*(C21-C22), the energy stabilised is 246.13 and 170.28 kcal/mol it is a significant stabilizing energy. Molecular Electrostatic Potential (MEP) shows that vast majority of each positive domain is near hydrogen atoms; almost all of the negative domain is close to NN atoms in both the gas and solvent phases. TDM (Transition Density Matrices) analysis presents graphical representations that depict the ability to transmit charges. Average local Ionization Energy (ALIE) scrutiny uses the colour blue to symbolize the stable sigma bonds, commonly linked to hydrogen atoms that generate protons. The choice of solvent significantly impacts its overall characteristics and chemical activity. In the topological aspect (with solvents), the most fragile acquaintances, binding zones, or the density of electron variations were all detected. Furthermore, a significant relationship exists between the electrical features of solvents and their polarization. According to Lipinski's rule of five, using a pill-sized quantity of such chemicals is generally safe. We also examined the molecule's biological activity by docking an adenogenic receptor. The anti-adenosine replicating protein (1Y56) binds most strongly (-7.10 kcal/mol) and interacts with other molecules in the most non-covalent ways.

Uncatalyzed Diboron Activation by a Strained Hydrocarbon: Experimental and Theoretical Study of [1.1.1]Propellane Diborylation.

The synthesis of strained carbocyclic building blocks is relevant for Medicinal Chemistry, and methylenecyclobutanes are particularly challenging with current synthetic technology. Careful inspection of the reactivity of [1.1.1]propellane and diboron reagents has revealed that bis(catecholato)diboron (B2cat2) can produce a bis(borylated) methylenecyclobutane in a few minutes at room temperature. This reaction constitutes the first example of B-B bond activation by a special apolar hydrocarbon and also the first time that propellane is electrophilically activated by boron. Mechanistic studies including in situ NMR kinetics and DFT calculations demonstrate that the diboron moiety can be directly activated through coordination with the inverted sigma bond of propellane, and reveal that DMF is involved in the stabilization of diboronate ylide intermediates rather than the activation of the B-B bond. These results enable new possibilities for both diboron and propellane chemistry, and for further developments in the synthesis of methylenecyclobutanes based on propellane strain release.

Conductive Gels for Energy Storage, Conversion, and Generation: Materials Design Strategies, Properties, and Applications.

Gel-based materials have garnered significant interest in recent years, primarily due to their remarkable structural flexibility, ease of modulation, and cost-effective synthesis methodologies. Specifically, polymer-based conductive gels, characterized by their unique conjugated structures incorporating both localized sigma and pi bonds, have emerged as materials of choice for a wide range of applications. These gels demonstrate an exceptional integration of solid and liquid phases within a three-dimensional matrix, further enhanced by the incorporation of conductive nanofillers. This unique composition endows them with a versatility that finds application across a diverse array of fields, including wearable energy devices, health monitoring systems, robotics, and devices designed for interactive human-body integration. The multifunctional nature of gel materials is evidenced by their inherent stretchability, self-healing capabilities, and conductivity (both ionic and electrical), alongside their multidimensional properties. However, the integration of these multidimensional properties into a single gel material, tailored to meet specific mechanical and chemical requirements across various applications, presents a significant challenge. This review aims to shed light on the current advancements in gel materials, with a particular focus on their application in various devices. Additionally, it critically assesses the limitations inherent in current material design strategies and proposes potential avenues for future research, particularly in the realm of conductive gels for energy applications.

Microscopic solvent-solute interactions, reactivity studies, structure properties and anti cancer activity of 1-(1-benzofuran-5-yl)-N-methylbutan-2-amine

Cancer continues to be a major threat to mankind, as seen by the 19.3 million people who received treatment for the disease in 2020. The study employed quantum mechanical calculations utilising (DFT) B3LYP, using a 6–311++ G(d,p) basis set, to analyse structural characteristics and intramolecular interactions and pharmaceutical aspect of anti-cancer. The study utilised various spectroscopy techniques, including FT-IR, FT-Raman and UV–Vis to examine the molecular arrangements of 1-(1-benzofuran-5-yl)-N-methylbutan-2-amine (1BF5MB).Significant interactions were seen because of the electron-density shift of nitrogen atom's lone pair (LP (O1)) to its antibonding orbital (σ ∗ ) (C13-H30), with an E(2) of 8.51 Kcal/mol. This indicates a substantial degree of electron delocalization. TDM analysis displays graphs that illustrate the capacity to transmit charges. ALIE analysis utilises the colour blue to represent the stable sigma bonds, namely those associated with hydrogen atoms that produce protons. Evaluating the drug-likeness and ADMET assessment enabled the biological features of (1BF5MB). This compound may be deemed a strong anti-tubercular treatment agent due to its relatively low binding affinities for the specific receptors.These results indicate that the drugs block these receptors.

Fungicide compound 2, 3-dichloronaphthalene-1, 4-dione: Non-covalent interactions (QTAIM, RDG and ELF), combined vibrational spectroscopic investigations using DFT approach with experimental analysis, electronic, molecular docking scrutiny in-vitro assay and thermodynamic property analysis

Structural features and intramolecular interactions have been investigated with quantum mechanical calculations using DFT at the B3LYP level using a 6-311G(d,p) basis set. The study employed several spectroscopic techniques, such as FT-IR, FT-Raman, and UV–Vis, to investigate the molecular structure of 2,3-dichloronaphthalene-1,4-dione (DCND). An energy of 14.82 kJ/mol is required to stabilize the connection between the LP(Cl13) and the antibonding C8-C7, which suggests significant delocalization. The TDM analysis reveals plots demonstrating the ability to transmit charges. In ALIE analysis blue is employed to depict the stable sigma bonds, which tend to be tied to hydrogen atoms that generate protons. Achieving drug-likeness and ADMET assessment allowed for the biological characteristics of DCND to be evaluated. For docking analysis, the most potent inhibitor, 4YNU, is particularly remarkable since it can form up to five C–H–O hydrogen bonds yielding a binding energy of −6.4 kcal/mol.

Isomerization pathway of a C–C sigma bond in a bis(octaazamacrocycle)dinickel(II) complex activated by deprotonation: a DFT study

The anti (a) to syn (s) isomerization pathway of the deprotonated form of the dimer with two nickel(II) 15-membered octaazamacrocyclic units connected via a carbon–carbon (C–C) σ bond was investigated. For the initial anti (a) structure, a deprotonation of one of the bridging (sp3 hybridized) carbon atoms is suggested to allow for an a to s geometry twist. A 360° scan around the bridging C–C dihedral angle was performed first to find an intermediate geometry. Subsequently, the isomerization pathway was explored via individual steps using a series of mode redundant geometry optimizations (internal coordinates potential energy surface scans) and geometry relaxations leading to the s structure. The prominent geometries (intermediates) of the isomerization pathway are chosen and compared to the a and s structures, and geometry relaxations of the protonated forms of selected intermediates are considered.

XUV Absorption Spectroscopy and Photoconversion of a Tin-Oxo Cage Photoresist.

Extreme ultraviolet lithography has recently been introduced in high-volume production of integrated circuits for manufacturing the smallest features in high-end computer chips. Hybrid organic/inorganic materials are considered as the next generation of photoresists for this technology, but detailed knowledge about the response of such materials to the ionizing radiation used (13.5 nm, 92 eV) is still scarce. In the present work, we use broadband high-harmonic radiation in the energy range 22-70 eV for absorption spectroscopy and photobleaching (that is, the decrease of absorbance) of thin films of an n-butyltin oxo-cage, a representative of the class of metal-based EUV photoresist. The shape of the absorption spectrum in the range 22-92 eV matches well with the spectrum predicted using tabulated atomic cross sections. The photobleaching results are consistent with loss of the butyl side groups due to the breaking of Sn-C bonds following photoionization. Bleaching is strongest in the low-energy range (<40 eV), where the absorption is largely due to the carbon atoms in the organic groups. At higher energies (42-70 eV), absorption is dominated by the tin atoms, and since these remain in the film after photoconversion, the absorption change in this region is smaller. It is estimated that after prolonged irradiation (up to ∼3 J cm-2 in the range 22-40 eV) about 70% of the hydrocarbon groups are removed from the film. The rate of bleaching is high at the beginning of exposure, but it rapidly decreases with increasing conversion. We rationalize this using density functional theory calculations: the first Sn-C bonds are efficiently cleaved (quantum yield Φ ≈ 0.9), because the highest occupied molecular orbitals (HOMOs) (from which an electron is removed after photoionization) are located on Sn-C sigma bonds. In the photoproducts, the HOMO is localized on tin atoms that have lost their hydrocarbon group (formally reduced to the Sn(II) oxidation state), and holes formed on those tin atoms lead to less efficient cleavage reactions. Our results reveal the primary reaction steps following excitation with ionizing radiation of tin-oxo cages. Our methodology represents a systematic approach of studying and quantitatively assessing the performance of new photoresists and as such enables the development of future EUV photoresists.

Bioinformatics study of selective inhibitor from &lt;i&gt;Garcinia mangostana&lt;/i&gt; L. tackle HIV‑1 infection

HIV has a host cell, T‑cell lymphocytes with CD4+ receptors. HIV drugs have the inhibitory activity on HIV‑1 protease by producing chemical bonding interactions such as hydrogen and hydrophobic. However, some cases show long-term side effects that may be harmful from the use of synthetic antiretrovirals. This requires new innovations to make drugs based on natural resources or alternative medicine for handling these cases. Natural-based drugs are claimed to reduce the side effects produced. Garcinia mangostana L. or queen of fruit is widely found in Southeast Asia. Many parts of this plant, such as fruits, are used for traditional medicine. Research with in vitro and in vivo approaches reveals that mangostin compounds from Garcinia mangostana L. can be an antiviral candidate. Garcinia mangostana L. has the main chemical compounds of garciniaxanthone, garcinone A, and mangostin. This study uses garciniaxanthone, garcinone A, and mangostin compounds to reveal the molecular mechanism of the antiviral activity in Garcinia mangostana L. through inhibition of HIV‑1 protease with a bioinformatics approach. In silico methods used in this study are druglikeness, molecular docking, interactions, visualization, and dynamic simulation. Garciniaxanthon B, garcinone B, and beta-mangostin from Garcinia mangostana L. have potential as antiretroviral agents for the treatment of HIV‑1 infection. The three compounds are predicted to inhibit the protease activity in HIV‑1 with a more negative binding affinity score, form ligand-protein molecular complexes with van der Waals, hydrogen, pi/alkyl/anion/ sigma bonds, form stable bonds and drug-like molecules.

DFT study, and natural bond orbital (NBO) population analysis of 2-(2-Hydroxyphenyl)-1-azaazulene tautomers and their mercapto analouges

Theoretical research on the keto-enol tautomerization of 2-(2-Hydroxyphenyl)-1-aza azulene (2HPhAZ) and its thiol-thione (2MPhAZ) analouge has been performed using the density functional B3LYP method with the 6–311 + + G(2d,2p) basis set in gas and ethanol phases. The findings of the MO computation on the energy scale and the prediction of the frontier molecular orbital (FMO) energies demonstrate that the tautomeric structures exist in a static mixture in the ground state, with the enol and thiol structure being more stable than the keto and thione structures in gas phase. The ethanol solvent causes some reordering of the relative stability of 2HPhAZ and 2MPhAZ conformers. The geometries created at the B3LYP/6–311 + + G(2d,2p) level of theory were used for NBO analysis. In the tautomerization of 2HPhAZ and its mercapto analogue 2-(2-Mercaptophenyl)-1-azaazulene (2MPhAZ), it has been found that the O(S)-C sigma bond is weak due to nO(S)—> σ*C25-O26(S26) and nO(S)—> σ*C15-N16 delocalization. It is also noted that the resulting p character of the corresponding oxygen (sulfur) natural hybrid orbital (NHO) of σO(S)-C bond orbital is related to the decreased occupancy of the localized σO(S)-C orbital in the idealized Lewis structure or the increased occupancy of σ*O(S)-C of the non-Lewis orbital and their subsequent impact on molecular stability and geometry (bond lengths) in gas phase and ethanol. Additionally, the energy of charge transfer decreases as the potential rotamers' Hammett constants (R1–R3 for O(S) atoms) increase. The partial charge distribution on the skeleton atoms demonstrates that the intra- and intermolecular interactions can be significantly influenced by the electrostatic attraction or repulsion between atoms. Lastly, the currently applied NBO-based HB strength indicator enables a fair prediction of the frequency of the proton donor NH stretching mode, but this simple picture is hidden by abundant hype conjugative effects.

Accidental triplet harvesting in donor-acceptor dyads with low spin-orbit coupling.

We present an accidental mechanism for efficient intersystem crossing (ISC) between singlet and triplet states with low spin-orbit coupling (SOC) in molecules having donor-acceptor (D-A) moieties separated by a Sigma bond. Our study shows that SOC between the lowest singlet excited state and the higher-lying triplet states, together with nuclear motion-driven coupling of this triplet state with lower-lying triplet states during the free rotation about a Sigma bond, is one of the possible ways to achieve the experimentally observed ISC rate for a class of D-A type photoredox catalysts. This mechanism is found to be the dominant contributor to the ISC process with the corresponding rate reaching a maximum at a dihedral angle in the range of 72°-78° between the D-A moieties of 10-(naphthalen-1-yl)-3,7-diphenyl-10H-phenoxazine and other molecules included in the study. We have further demonstrated that the same mechanism is operative in a specific spirobis[anthracene]dione molecule, where the D and A moieties are interlocked near to the optimal dihedral angle, indicating the plausible effectiveness of the proposed mechanism. The present finding is expected to have implications in strategies for the synthesis of new generations of triplet-harvesting organic molecules.

An ab initio journey into the electronic structure of Be3

In the present study, we concisely report on Be3’s ground and several excited states of singlet, triplet, quintet, and septet spin symmetry at the MRCI/aug−cc−pV5Z computational level. We have constructed potential energy cuts along the bending coordinate under both C2v and C s symmetry constraints. Both linear and bent configurations have been calculated that span an energy range of nearly 160 kcal/mol. The excited states result by promoting one, two or three valence electrons from the ground state’s electronic configuration. This electronic promotion destroys its sigma (2center – 2e−) bond(s) and the resulting asymmetry is at the very heart of the Jahn–Teller distortion.

Electrochemical Reduction of C-O Bonds

Reductive activation and transformation of C-O bonds in alcohols have been a challenge for many decades, yet is still considered an important step in the process of converting biomass into biofuel and chemicals. The challenge arises from the cleavage of the carbon-oxygen bond which generally requires forcing conditions and is reflected in the high bond dissociation energy compared to other polarised sigma bonds.[1] Our project focuses on electroreductive cleavage of alcohols in the presence of a hydrogen donor in an undivided cell with up to 95% of the corresponding alkane. C-O transformation is also accomplished through carboxylation with carbon dioxide, resulting in yield up to 43%.[2][1] Villo, P.; Shatskiy, A.; Kärkäs, M. D.; Lundberg, H. Electrosynthetic C−O Bond Activation in Alcohols and Alcohol Derivatives. Angewandte Chemie International Edition 2023, 62 (4), e202211952. https://doi.org/10.1002/anie.202211952.[2] Villo, P.; Lill, M.; Alsaman, Z.; Kronberg, A. S.; Chu, V.; Ahumada, G.; Agarwala, H.; Ahlquist, M.; Lundberg, H. Electroreductive Deoxygenative C–H and C–C Bond Formation from Non-Derivatized Alcohols Fueled by Borohydride Oxidation. ChemRxiv August 2, 2023. https://doi.org/10.26434/chemrxiv-2023-tw9l1-v2. Figure 1

Densely crosslinked protein bioplastics with superior stretchability and desirable wet stability via quality protein restoration

We have demonstrated that dithiol-based crosslinkers are most suitable for protein materials with high contents of cysteine. Crosslinking is always the effective approach to improvement in properties of protein materials. However, most crosslinking technologies damage structures of protein materials due to harsh crosslinking conditions, or form uncontrollable and unstable crosslinkages. In this work, we selected dithiols with different chain lengths and flexibility to form disulfide crosslinkages via reduction and oxidation at room temperature. Sustainable dithiols were screened by computational simulation for bioplastic uses. Since the reactions were performed at room temperature, keratin backbone structures were intact. Our developed model indicates that number of sigma bonds in crosslinkages and retention of crosslinking, dominated by sigma bonds in crosslinkages, quantitatively controlled mechanical properties of regenerated keratin films. Wet-stable keratin films with excellent stretchability were developed without any plasticizers and secondary polymers. Some properties of our bioplastics via quality restoration were similar to some petroleum-based products. For example, feather-derived bioplastics had dry stress, wet stress, dry breaking elongation, and wet elongation of 35 MPa, 10.2 MPa, 70%, and 105%, respectively. After seven days in water, the stress retention of films was as high as 85%. This work promoted the application of keratin bioplastics in food, pharmaceutical and cosmetic industries.

Synthesis, Characteristics and Applications of Graphene Composites: A Survey

Graphene is the name for a monolayer sheet of carbon atoms that are bonded together in a repeating pattern of hexagons. This sheet is only one atom thick. Monolayers of graphene stacked on top of each other. In this article, we have compared the characterization results of graphene and graphene oxide along with synthesis via different methods. A sigma bond connects each atom in a graphene sheet to its three closest neighbours and each atom also contributes one electron to a conduction band that covers the entire graphene sheet. Graphene when oxidized is called graphene oxide (GO) and is mostly used in photoelectric, materialistic, catalyst and energy fields due to its thermal, electrical and mechanical characteristics. It is also used in the field of medical science, drug delivery and biomedical applications. Graphene have been improved due to import of 3D printing technology. In last few years, graphene has taken the attention of most material science researchers due to its various applications. Graphene based polymers and nanocomposites are widely used in sensors, optoelectronics, magneto transport, automotive, biosensors, electronics and aerospace fields.