Molecular Systems Design & Engineering最新文献

The growing demand for solute selective separations necessitates the development of materials and processes capable of separating species of similar charge and size. Polymeric ion pumps, which are composite membranes composed of a gate layer situated on top of a sorbent layer, have the potential to address this opportunity. The gate and sorbent layers are designed to undergo changes in permeability and affinity, respectively, in response to an external stimulus. Subsequently, cyclic changes in the stimulus promote the selective transport of a target solute. Within this study, a mathematical model and numerical solver were developed to investigate the effect of the gate layer resistance on the performance of polymeric ion pumps. Notably, imperfect gate layers lead to solute diffusing back into the feed solution, reducing but not irrevocably hindering membrane performance. In the limit of high sorbent densities, the fraction of solute diffusing into the receiving solution is determined by the relative resistances of the gate and sorbent layers while the total flux of the target solute increases in proportion to the sorbent density. The analysis highlights that current materials possess the necessary properties to fabricate polymeric ions pumps with performances that exceed conventional membrane systems. Enhancing the performance of polymeric ion pumps will rely on identifying material combinations that respond coherently to rapidly changing stimuli.

Coordination polymers (CPs) are a scientifically compelling and evolving class of highly crystalline materials. Owing to their controllable structures and morphologies, CPs can be used as a type of uniformly and periodically atom-distributed precursor and efficient self-sacrificial template to fabricate porous-carbon-related functional materials. In this work, we have used CuCl₂·2H₂O or Cu(NO₃)₂·3H₂O to combine with N,N′-bis(3-pyridinecarboxamide)-1,2-cyclohexane (3-bpah) to construct Cu(I)-based CPs, namely [Cu(3-bpah)Cl]·H₂O (1) and [Cu(3-bpah)(NO₃)] (2), respectively. We have studied the effect of anions on the structure of the compound in detail. Moreover, the two Cu(I)-based CPs were used as precursors for the preparation of derived materials; then foreign elements were doped into the intrinsic CP-based derived materials and their properties were explored. The adsorption capacities and photocatalytic activities were studied in detail.

Multiple ring-closing metathesis of oligomeric bithiophene smoothly formed a winding vine-shaped oligomer with molecular asymmetry. Stereochemical studies suggested that the dimeric 1 : 1 meso and racemic stereochemical mixture showed the conversion to a meso-enriched product upon standing in the solid state, while the obtained meso compound reverted to the meso and racemic mixture upon heating the solution in chloroform at 50 °C for 30 min. On the other hand, heating of the meso isomer in the solid state at 80 °C for 3 days did not lead to isomerization.

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Post-synthetic modification (PSM) is a powerful tool for introducing complex functionalities into metal–organic frameworks (MOFs). Aldehyde-tagged MOFs are particularly appealing platforms for covalent PSM due to the high reactivity of aldehyde groups, but the same feature also makes their solvothermal synthesis challenging. In this work, we show that while lowering the temperature during the synthesis of aldehyde-tagged UiO-68 avoids aldehyde group degradation and yields a highly porous and crystalline material, the resulting UiO-68–CHO contains a large fraction of missing linker defects and, as a result, its PSM is both inefficient and non-repeatable. However, we also show that this problem could be solved by 1) using an excess of linker during the synthesis of the MOF and 2) by soaking the crude material in the solution of the linker, which together reduce the density of defects enough to yield an excellent substrate for PSM. Treatment of the ‘healed’ material with model amines gives nearly quantitative conversions of aldehydes into imines, even if no excess of reagents is used. Importantly, the PSM of the ‘healed’ UiO-68–CHO gives repeatable results over many days, unlike the PSM of the highly defective MOF. Owing to these developments, various functionalities, such as new coordination sites, drug cargo, chirality, and hydrophobicity, were successfully introduced into the UiO-68 framework. The deleterious influence of defects on the PSM of MOFs and the solution to this problem proposed herein are likely to be of general nature and hence might help in developing new and versatile platforms for covalent PSMs.

The state of proteins in aqueous solution is determined by weak, nonspecific interactions affected by pH, solvent composition, and ionic strength. Protein–protein interactions play a crucial role in determining protein stability and solubility. The second osmotic coefficient (B₂₂) provides insight into effective interactions between proteins in solution. Models for calculating B₂₂ are valuable for estimating interactions, explaining measured phenomena, and reducing experimental time. However, existing models, like the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, assume a simple spherical shape for proteins. Owing to the fact that proteins exhibit diverse shapes and charge distributions, influencing their electrostatic properties and overall interactions, DLVO accuracy is significantly reduced for nonspherical proteins. To address this limitation, we introduce the xDLVO-CGhybr model, which combines Poisson–Boltzmann (PB) and Debye–Hückel (DH) theories to account for electrostatic interactions between proteins. PB is used for short intermolecular distances (<2 nm) with an all-atom resolution, while DH is employed for longer distances on a coarse-grained level. Additionally, xDLVO-CGhybr incorporates an improved coarse-grained Lennard-Jones (LJ) potential derived directly from the all-atom potential to capture dispersion interactions. This model improves the calculated B₂₂ values compared to existing models and can be applied to proteins with arbitrary shape and charge under various solvent conditions (up to 1 M monovalent salt concentration). We demonstrate the application of xDLVO-CGhybr to bovine trypsin inhibitor, ribonuclease A, chymotrypsinogen, concanavalin A, bovine serum albumin, and human immunoglobulin type I proteins, validating the model against experimental data.

A donor–π–acceptor type photoinitiator, composed of boron–thienothiophene–triphenylamine (DMB–TT–TPA) to be used as a synthesizer under white LED irradiation, was studied for cationic and radical polymerization of mono and difunctional monomers. The monomers methyl methacrylate (MMA), styrene (Sty), cyclohexene oxide (CHO), isobutyl vinyl ether (IBVE), triethylene glycol dimethacrylate (TEGDMA) and bisphenol A diglycidyl ether (BADGE) were exposed to irradiation under a white LED source in CH₂Cl₂ with DMB–TT–TPA, in the presence of diphenyliodonium hexafluorophosphate (DPI). Of the spectroscopic techniques, fluorescence was used to investigate the photophysical characteristics of DMB–TT–TPA to gather data that would be helpful in affirming the initiation process. The presence of the synthesizer in all the polymer structures was proved by NMR spectroscopy studies. The importance of the described photoinduced electron transfer process with respect to the initiation of radical and cationic polymerizations and formation of conjugated polymers was demonstrated.

Ring-opening metathesis polymerisation (ROMP) has become a popular method for synthesising complex functional polymers owing to the high functional group tolerance of metathesis catalysts. In recent years, ROMP has emerged as an indispensable approach for the design and synthesis of polymeric biomaterials, allowing for precise control of polymer structure and introduction of complex polar functional groups that are challenging to access through conventional polymerisation methods. In this review, we present examples of precision polymer synthesis with polar functional groups and their utilisation as soft-biomaterials in biotechnology and biomedical fields. Specifically, we focus on two approaches: the underexplored ROMP of functionalised monocyclic alkenes and the dominant methods of synthesising biomaterials using functionalised norbornene.

The production of ordered mesoporous carbons (OMCs) can be achieved by direct pyrolysis of self-assembled polymers. Typically, these systems require a majority phase capable of producing carbon, and a minority phase to form pores through a thermal decomposition step. While polyacrylonitrile (PAN)-based block copolymers (BCPs) have been broadly reported as OMC precursors, these materials have a relatively narrow processing window for developing ordered nanostructures and often require sophisticated chemistry for BCP synthesis, followed by long crosslinking times at high temperatures. Alternatively, olefinic thermoplastic elastomers (TPEs) can be convered to large-pore OMCs after two steps of sulfonation-induced crosslinking and carbonization. Building on this platform, this work focuses on the precursor design concept for the efficient synthesis of OMCs through employing low-cost and widely available polystyrene-block-polybutadiene-block-polystyrene (SBS), which contains unsaturated bonds along the polymer backbone. As a result, the presence of alkene groups greatly enhances the kinetics of sulfonation-induced crosslinking reaction, which can be completed within only 20 min at 150 °C, nearly an order of magnitude faster than a recently reported TPE system containing a fully saturated polymer backbone. The crosslinking reaction enables the production of OMCs with pore sizes (∼9.5 nm) larger than most conventional soft-templating systems, while also doping sulfur heteroatoms into the carbon framework of the final products. This work demonstrates efficient synthesis of OMCs from TPE precursors which have a great potential for scaled production, and the resulting products may have broad applications such as for drug delivery and energy storage.

One of the cancer treatment methods is the use of doxorubicin as a chemotherapy drug. Despite its effectiveness, it has low specificity and high toxicity, thus affecting healthy cells in the body. One approach to reducing toxicity to healthy cells is the delivery of the active compound by a nanoparticulate system. The proposed doxorubicin transport system by polyamidoamine (PAMAM) dendrimer molecules was carried out experimentally, but the mechanism involved in this interaction has not yet been demonstrated. In this contribution, the interactions that occur in a nanoparticulate system with potential for a controlled drug release were described using density functional theory, as implemented in the SIESTA code. The delivery system is formed by a PAMAM dendritic molecule, the drug doxorubicin and two targeting molecules, namely folic acid and cis-aconitic anhydride. The results show that there is a hydrogen bonding interaction between PAMAM and doxorubicin, and the influence of targeting molecules is promising. An increase in the stability was observed when the cis-aconitic anhydride interacts with PAMAM. For all the configurations tested, the presence of a doxorubicin molecule changes the electronic properties of the PAMAM dendrimer, showing that the adsorption occurs for all the systems proposed.