Molecular Systems Design & Engineering最新文献

Owing to their excellent fluorescence properties, coumarin derivatives have diverse applications in phototherapy and optoelectronics. Coumarin derivatives with a trifluoromethyl group at the 4-position have been extensively investigated; however, studies on the photophysical properties of fluorescent 3-trifluoromethylated coumarins in solution and in the solid state are rare. Hence, in this study, the photochemical properties of a coumarin derivative incorporating a promising electron-withdrawing fluoroalkyl group at the 3-position in solution and in the crystal form were investigated in detail by absorption and fluorescence spectral measurements, density functional theory and time-dependent density functional theory calculations, and single crystal X-ray structure analysis. The aim was to verify the reasons for its excellent fluorescence emission in solution and in the crystal form. These molecular compounds are expected to have potential applications as coumarin fluorophores in fluorescent emission probes and electronic light-emitting devices.

Recent progress in bone tissue engineering (BTE) has introduced alternative treatments for sizable and non-healing bone defects. Electrical stimulation (ES) has recently been shown to influence bone cells and foster processes such as adhesion, migration, proliferation, and differentiation, which can enhance the bone regeneration process. In this study, we synthesized molybdenum disulfide (MoS₂) nanoparticles (NPs) and incorporated them into a polycaprolactone (PCL) polymeric matrix to enhance the electrical conductivity of scaffolds. The PCL/MoS₂ nanocomposites were analysed using scanning electron microscopy (SEM), water contact angle measurement, electrical conductivity, and tensile strength assessments. In vitro studies evaluated the adhesion of mesenchymal stem cells (MSCs) and the biocompatibility of the fabricated scaffolds using the MTT assay. Biomineral crystal deposition was determined via in vitro simulated body fluid (SBF) biomineralization, and alizarin red S assays demonstrated enhanced calcium phosphate deposition on the PCL/MoS₂ composite scaffold. Additionally, qPCR analysis revealed that exposing MSCs cultured on PCL/MoS₂ to ES for two weeks transcriptionally upregulated osteogenic markers (osteocalcin (OC) and alkaline phosphatase (ALP)) in cells. Using either ES or a differentiation medium alone could enhance osteogenesis. However, when both stimuli were applied concurrently, improved levels of osteogenic markers were observed. Our findings suggest that ES plays a significant role in boosting osteogenic differentiation, particularly when combined with MoS₂NPs as an osteogenic enhancer. Therefore, PCL/MoS₂ nanofibrous scaffolds can be proposed as suitable candidates for BTE, and ES holds great potential as an effective tool along with commonly used biomaterial scaffolds.

Designing donor–acceptor polymers by incorporating additional donor or acceptor units in the polymer backbone has attracted significant interest for further tuning of physical and chemical properties for organic electronic applications. In this study, we design and synthesize random donor–acceptor–donor–acceptor (D–A–D–A′, P1) and acceptor–donor–acceptor–acceptor (A–D–A′–A, P2) polymers using direct heteroarylation polymerization. Polymer P1 has alternating donor and acceptor units, whereas polymer P2 has an additional acceptor unit. For comparison purposes with parent polymers, three donor–acceptor polymers (P3–5) were synthesized. All polymers P1–5 were synthesized from three precursor units, 5-fluoro-2,1,3-benzothiadiazole, 5-diethylhexyl-3,6-bis(thiophene-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione and 3-hexylthiophene, using different compositions and sequences. Structural characterization of polymers P1–5 was carried out by ¹H NMR, GPC and FTIR spectroscopy. The electrochemical, stability and optical properties of polymers P1–5 were investigated by cyclic voltammetry and UV-vis-NIR absorption spectroscopy. All polymers exhibited narrow optical band gaps. The absorption of these polymers was red-shifted (30–100 nm) in the solid state compared to in a solution. It was observed that copolymers have different optical and electrical properties from their parent donor–acceptor polymers. Therefore, it is an effective method for the synthesis of donor–acceptor polymers with additional donor or acceptor units to tune the properties of the polymers for flexible electronic applications.

The application of single-atom catalysts offers an auspicious resolution to the obstacles introduced by the polysulfide shuttle phenomenon and the sluggish sulfur conversion kinetics in lithium–sulfur batteries (LSBs). This research presents results regarding a sulfur host that demonstrates redox activity and resistance to polymeric sulfur species (PSS). High-curvature carbon nanotubes are utilized in the construction of a single atom CoN₄ catalyst through a series of steps including pyrolysis, surface processing, electrostatic adsorption, and polymerization. Undoubtedly, the presence of cobalt (Co) atoms as discrete entities was revealed by X-ray absorption spectroscopy and transmission electron microscopy, as these atoms showed dimensions consistent with the sulfur components on the cathode side. This configuration enables catalytic activity with a remarkable 100% atomic utilization functionality. Furthermore, the DFT calculation of free energy values indicates that the reduction of LiPSs on the carbon nanotube with surface curvature is more advantageous compared to the planar carbon surface. The obtained data suggest that the sulfur cathode, which was fabricated utilizing CoSAC/CNT, demonstrates electrocatalytic capability in the transformation of soluble polysulfides to insoluble Li₂S. As a consequence, the detrimental effects of the polysulfide shuttle effect are mitigated. The recently introduced sulfur host in the LSB exhibits consistent performance over 1000 cycles. It sustains a capacity of 990 mA h g⁻¹ at a rate of 1C, with a sulfur loading of 2.0 mg cm⁻². An impressive area-specific power of 4.1 mA h cm⁻² is achieved with a considerable sulfur loading of 7 mg cm⁻². This single-atom cobalt catalyst shows significant potential as a next-generation cathode material for LSBs.

Creation of imprinted proteins (IPs) as a synthetic alternative to natural recognition systems is an important task for chemical engineering. However, the knowledge available on the theoretical study of IPs as recognition systems is limited. In this study, combined molecular docking and molecular dynamics methods were applied for the first time to study the albumin-based IPs against foodborne toxins. Changes in protein structure and intermolecular interactions between protein and foodborne toxin molecules were evaluated. Based on these theoretical computations, insights into the rational design for IPs were submitted. This approach is extremely promising for demonstrating the IP formation mechanism, identifying their properties, and introducing new concepts of IP creation based on controlling the synthesis conditions.

We study a coarse-grained model of a nanocomposite consisting of a symmetric AB diblock copolymer and a planar nanoparticle (NP) using dissipative particle dynamics. The NP size exceeds the period of the lamellar domains formed by microphase separation of the copolymer blocks. The model predicts that the NP has two stable orientations due to its anisotropic nature and the difference between the NP size and the period of the matrix domains. In the case of good or poor compatibility of the NP with both copolymer blocks, the NP plane is oriented perpendicular to the plane of the matrix domains. In the case of selective interaction with the copolymer, the NP will be incorporated into the domain formed by the blocks with which it has the greatest compatibility. The appearance of the orientational ordering effect is explained by the imbalance in the distribution of copolymer blocks along the NP surface in the early stages of the microphase separation. This result allows us to consider this system as a two-state nanocomposite. It is also observed that the introduction of the NP reduces the incompatibility threshold of the copolymer blocks above which microphase separation occurs. We hope that the reported effect will be useful for the design of smart nanomaterials with switchable properties.

Singlet fission has the potential to significantly improve the efficiency of photovoltaic devices by harnessing high-energy sunlight to double the photocurrent that can be generated in standard semiconductors. The challenge is identifying materials capable of undergoing this process efficiently. Herein, we present the results of a systematic search for novel intermolecular singlet fission materials based on the recently synthesized 6,6′-biphenanthridine (biphe) framework utilizing a straightforward computational approach. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were employed to study the photophysics of various structural analogues of biphe. These analogues were generated in silico by utilizing an extensive range of transformations, including planarization, protonation, symmetric and asymmetric alkylation, electron-donating and electron-withdrawing group substitution, N-oxide substitution, and symmetric and asymmetric π-extension and contraction. Analysis of the effects of these structural modifications on the energies of the lowest singlet and triplet excited states revealed that (2,2′,10,10′-tetra-N-oxide) planar biphe has an E(S₁)/E(T₁) ratio of 2.12 and an E(T₂)/E(T₁) of 2.05, suggesting its potential for intermolecular singlet fission. Additionally, N-methylated biphe emerged as a promising contender for thermally activated delayed fluorescence. The effects of solvation are also discussed.

Structure formation and rheological properties of amphiphilic patchy nanocubes in equilibrium and under shear were investigated using hybrid molecular dynamics simulations combined with multiparticle collision dynamics that consider hydrodynamic interactions. The relationship between complex self-assembled structures and the resulting macroscopic properties has not yet been examined because of the computational complexity these multiscale problems present. The number and location of solvophobic patches on the amphiphilic nanocubes were varied at several colloid volume fractions in the liquid regime. For a pure suspension of one-patch cubes, the nanocubes self-assemble into dimers in the equilibrium state because bonded one-patch cubes have no exposed solvophobic surfaces. At low shear rates, small dimers undergo shear-induced alignment along the flow direction. This results in shear-thinning accompanied by slightly higher shear viscosity (≈15%) than homoparticle dispersions of the same concentration. As the shear rate increases further, the suspensions exhibit Newtonian-like behavior until the cluster disintegrates, followed by shear thinning with breakdown into individual cubes. For binary mixtures of one- and two-patch nanocubes, the resulting cluster shapes, which include elongated rods and fractal objects, can be controlled by the patch arrangements on the two-patch cubes. Interestingly, despite the differences in the shape and resistance of the clusters, two different mixtures undergo a similar increase in the shear viscosity (≈35%) compared to the homoparticle dispersions, to essentially exhibit rheological behavior similar that of a pure suspension of one-patch cubes. Our findings provide new insights into the correlation between microscopic (design of patchy cubes), mesoscopic (self-assembled structures), and macroscopic (viscosity) properties, and are also valuable for identifying the synthesis conditions required to realize novel materials with the desired properties and functionalities.

Optoelectronic properties of organic photovoltaics, including light absorption, intramolecular and intermolecular charge transfer, depend on the energetics of the frontier molecular orbitals of constituent organic materials. We develop a tight-binding model for an indacenodithiophene-based small molecule non-fullerene acceptor – IDTBR, which gives a high-efficiency organic photovoltaic cell in combination with poly(3-hexylthiophene) as donor. By choosing stiff conjugated ring moieties as sites, we obtain tight-binding parameters that are local to each moiety, and transferable to other chain architectures. In particular, parameters from homo-oligomers and alternating co-oligomers of constituent moieties can be used, without adjustment, to define the tight-binding model for IDTBR, which reasonably predicts the energies and wavefunctions of its frontier molecular orbitals. Transferability of model parameters will enable efficient screening and selection of molecular architectures with desirable optoelectronic properties.

The sustainable synthesis of porous polymer monoliths has significant advantages over powdered porous polymers and is capable of adsorbing multiple types of pollutants efficiently from water. They are important as an easily affordable material for water purification. Herein, we report the synthesis of mesoporous chitosan, PEG monoliths, via the crosslinking of chitosan with PEG-diacrylate macro-crosslinkers using aza-Michael reactions in water. The surface area and pore volume are tuned by varying the crosslinking density and length of the macro-crosslinker. The materials show very good thermal and chemical stability against organic and aqueous (within pH 2–9) solvents. The monolith is capable of removing a wide range of both organic and inorganic pollutants, such as anionic dyes, metal ions, iodine, and pharmaceuticals, from contaminated water. The reusability of the monolith after it is regeneration by releasing the adsorbed pollutant is important for its affordable practical application. In addition, the monolith can be completely degraded in a strong alkaline solution to quantitatively recycle the chitosan derivative.