An auspicious thermoplastic polyurethane (TPU) monolith has been prepared by a facile and cost-effective method of thermally induced phase separation (TIPS). With superb porous structure, excellent hydrophobicity/oleophilicity, and superior elasticity, the obtained TPU monolith exhibits an outstanding adsorption capacity, high oil/water separation efficiency, and good recycling performance, achieving the goal of treating waste with waste.
A methylene group was introduced into the C–H bond of α-carbonyl aldonitrones by reaction with dimethylsulfoxonium methylide, producing one-carbon homologated C-methyl ketonitrones. This formal methylene insertion was applied to one-pot synthesis of quaternary C3-methyl isoxazolidines via successive 1,3-dipolar cycloaddition with alkenes bearing an electron withdrawing group.
Mixtures of the ionic liquids 1-methyl-3-octylimidazolium phenylazophenolate, abbreviated as [C8mim][AzoO] and 1-methyl-3-octylimidazolium hexafluorophosphate, abbreviated as [C8mim][PF6], have been known as smart materials with high moldability, electric conductivity, and self-healing properties. However, the structure and the phase behavior at low temperature are not well known in detail, which may change depending on the composition. Differential scanning calorimetry shows that a tiny amount of water is required for the crystallization of neat [C8mim][AzoO]. X-ray diffraction profiles indicate the coexistence of the crystalline phase and the liquid state for the one-component ionic liquid. Polarized optical microscopy indicates that the crystalline phase comprises needle-like microcrystals and coarse crystals. As a result, the phase diagram of the mixture [C8mim][AzoO]n[PF6]1−n is established. The mixture undergoes a complex phase behavior containing glass transition and crystallization, which drastically changes depending on the composition. Noteworthy, it is indicated that [C8mim][PF6] promotes the formation of microcrystals of [C8mim][AzoO], but not coarse crystals. On the other hand, [C8mim][AzoO] facilitates the supercooling of the liquid [C8mim][PF6]. These asymmetric effects enable [C8mim][AzoO]n[PF6]1−n to display moldable but electroconductive features.
The radical polymerization of methyl acrylate in the presence of a palladium dimer complex and ethyl iodoacetate as an initiator under photoirradiation conditions led to the formation of poly(methyl acrylate) having good Ð values. The polymerization could be controlled by switching the light on and off, exhibiting living characteristics. We propose that such α-Pd polyesters could function as dormant species, which would allow a pair of transient α-keto radicals and persistent Pd radicals to be generated upon photoirradiation.
To study the possibility of controlling molecular assemblies such as monolayers by using chirality, we synthesized 1-[1-(6-stearyl)pyrenyl]ethanol (SP6E), a novel amphiphilic molecule with a chiral center in the hydrophilic part and a pyrene ring in the long-chain alkyl backbone. The structures of racemic and optically active monolayers of SP6E were characterized using the π–A isotherm and analyzed by Brewster angle microscopy, surface fluorescence spectroscopy, and atomic force microscopy (AFM). The results showed that (±)-SP6E formed solid solution-like monolayers without any regular structure. By contrast, a one-dimensional columnar structure was observed in the (S)-(−)-SP6E monolayer by AFM, thereby confirming the formation of a relatively controlled monolayer structure. The successful structural control in (S)-(−)-SP6E is considered achieved through the cooperative effects of chirality and π–π stacking of the pyrene ring. Thus, this study demonstrates the possibility of controlling the structure and orientation of molecular assemblies by appropriately combining chirality and other intermolecular interactions based on molecular design. This approach is a promising strategy for developing surface materials and interfacial nanoarchitectonics with precisely controlled molecular orientations.
We found bursts of DNA double-strand breaks by a dicopper(II) complex with a p-cresol-2,6-bis(amide-tether-dpa) ligand (HL) [Cu2(μ-1,1-OAc)(μ-1,3-OAc)(L)]2+ (1) via reductive O2-activa-tion with sodium ascorbate (AscNa) under air, where 26% of supercoiled plasmid DNA was converted to linear form in 1 min. The reasons for bursts of DNA double-strand breaks by 1 were clarified in comparison with a Robson type dicopper complex [Cu2(μ-OH)(bpmp)]2+ (2) and an iron complex of N4Py ligand [Fe(MeCN)(N4Py)]2+ (3). Spectroscopic, electrochemical, and kinetic studies revealed that upon reaction with AscNa, 1 is rapidly reduced to Cu(I)Cu(II) and Cu(I)Cu(I) species, which are involved in rate-limiting three electron reduction of O2 to HO• responsible for the DNA cleavage. The HO• formation was monitored by emission spectral change of terephthalic acid (TA). DNA binding abilities of 1 and 3 were examined by isothermal titration calorimetry (ITC) and electronic absorption spectral and IR spectral changes. These revealed that the rapid HO• formation and the large binding number and rigid binding to DNA are key features of 1 to enable the burst of DNA double-strand breaks.
A nickel(II) complex of methyl pyropheophorbide-a bearing a vinyl group at the 3-position was treated with methanesulfonic acid in refluxing benzene to give smoothly the corresponding 3-devinylated product. The 7- and 8-vinyl groups in the related chlorophyll-a/b derivatives were readily removed under the same conditions, while the 12-vinyl group neighboring the electron-withdrawing 13-keto carbonyl moiety was hardly defunctionalized. The devinylations blue-shifted all the visible absorption bands in dichloromethane. The deethylation at the 3-position bathochromically moved the redmost Qy maximum, and the dealkylations at the 7-, 8-, and 12-positions hypsochromically moved the Qy(0,0) maxima, which were reproduced by time-dependent density functional theory calculation. Since no vinyl periphery in the free base counterparts was removed under the mild conditions, nickel 3-unsubstituted deoxophylloerythroporphyrin in geological samples would be produced via the nickel metalation of chlorophylls-a/b/c from ancient phototrophs or their derivatives followed by the acidic 3-devinylation.
The conversion of cisplatin Pt(II) into a Pt(IV) complex is a strategy that can be used to overcome cisplatin resistance and side effects, and this involves the functionalization of the axial positions of cisplatin. Using ligands with bioactivity to target specific cancer cell species could lead to targeted treatment and mitigate severe side effects. Furthermore, enhanced cellular uptake could be used to overcome cisplatin resistance. Anchoring the “dual-acting” prodrug in self-assembled hybrid porous metal-organic frameworks (MOFs) has revealed an even more advanced treatment. The exceptional porosity allows high loading of the drug, and the easily tuned functional groups within the frameworks enable various interactions between the drug and the cargo material to optimize controlled release and prevent premature release. Some MOFs have also demonstrated cytotoxicity against several cancer lines. It is expected that the combination of the prodrug and active MOFs could generate a “triple-acting” anticancer agent for more enhanced cancer treatment. This review discusses the development of cisplatin modified with several prodrugs and its anticancer activity in several cancer cell lines. Furthermore, the review summarizes the involvement of cisplatin derivatives in MOFs, highlighting the slow, controlled, and targeted delivery of the drug and its anticancer activity.
In the early 2000s, an epoch-making discovery of phosphorothioated DNA (PS-DNA, also as medicines) was made to show that sulfur atoms are present on the DNA backbone in microorganisms. However, its reaction activity and mechanism have not been well clarified. We show that PS-DNA is cleaved efficiently via oxidation, but not previously believed alkylation; this sulfur modification can be repaired by desulphurization once the sulfhydryl is further oxidized. When Tris or other ethanolamine derivatives are present, the cleavage becomes extremely efficient. Analyzed by enzymatic digestion, ligation, and mass spectroscopy, a mechanism is proposed to explain effects of ethanolamine derivatives and the competition between repair and breakage. Tris favors cleavage by keeping and utilizing the oxidation at –S(O)OH (sulfinic group) stage. The hydroxyl group on ethanolamine derivatives attacks the activated phosphor atom for cleavage with an intramolecular-like mode to form simultaneously a phosphoester bond. Desulphurization is dominant once the PS-DNA is oxidized to –S(O2)OH (sulfonic group). We believe that the biological significance of PS-DNA is protection of DNA nucleobases from weak oxidants by direct repairing or cleavage-repairing approach, which is affected by amines. Besides understanding the biological significance of PS-DNA, our findings will contribute greatly to developing new bio-techniques and nucleic acid medicines.
A Negishi coupling based synthesis of 1,2,4,5-tetra(9-anthryl)benzene derivatives, possessing X-shaped molecular structures, is described. The results of X-ray crystallographic analysis show that two-dimensional highly ordered packing structure of the crystalline state of the unsubstituted derivative is a consequence of intermolecular π-π and CH-π interactions between anthracene units. Photoirradiation of the unsubstituted derivative as a precipitated solution promotes intramolecular [4+4] photocycloaddition reactions between both adjacent pairs of anthracene units to produce a crystalline polycyclic product having a unique 1.700 Å long carbon-carbon single bond. Furthermore, charge-transfer complexes, displaying near-infrared absorption and emission, are generated by co-crystallization of the X-shaped unsubstituted member of the group with electron-acceptor molecules.
Aromatic hydrocarbons are indispensable components of functional organic materials. An sp2-hybridized carbon atom can form a nonplanar structure through an appropriate molecular design, and this structural flexibility enables the construction of a wide variety of nonplanar aromatic hydrocarbons. We have studied the chemistry of nonplanar aromatic hydrocarbons and succeeded in synthesizing highly strained structures. The key to this series of studies is the development of innovative strain-release methods. This account introduces our 10-year research campaign on the synthesis of highly strained nonplanar aromatic hydrocarbons, categorized into (i) ring-shaped arenes (e.g., cycloparaphenylenes), (ii) belt-shaped arenes (e.g., carbon nanobelts), (iii) warped arenes (e.g., warped nanographenes), (iv) helical arenes, and (v) topologically unique arenes.
We performed molecular dynamics (MD) simulations (57 µs in total) to examine the formation of a typical antigen–antibody complex, that of hen egg-white lysozyme (HEL) and its antibody, HyHEL-10. We observed that HEL and HyHEL-10 successfully formed native complexes in several MD simulations. Energetic analyses showed that native complexes tend to have lower interaction energies than most of the other encounter complexes, which is a useful feature for computational complex structure prediction. In the stabilization process, we found that the N32L residue underwent a characteristic conformational change (structural locking), which significantly enhanced the interaction energy. In addition, we performed MD simulations for the N32LD mutein. The results showed that the N32LD mutation enhanced the electrostatic interaction and accelerated the encounter dynamics. However, in the stabilization process, the N32LD mutation deteriorated the structural locking role of N32L, and therefore we could not find any specific conformational change to stabilize the complex structure. The resultant loose feature of the N32LD complex is consistent with experimental observations that the N32LD mutation decreases binding affinity but leads to a large entropic gain.
Dielectric properties of co-extruded triple-layered films consisting of polymethyl methacrylate (PMMA) sandwiched between polyvinylidene fluoride (PVDF) layers were evaluated. The triple-layered films showed a higher dielectric breakdown strength and a higher energy density than each single-layer film, and the enhancement depended on the volume ratio of the PMMA layer, which has a lower relative dielectric constant than PVDF. The simulation of dielectric breakdown paths using the phase-field model revealed that the middle layer with a lower dielectric constant shares a higher voltage until its dielectric breakdown, resulting in an enhancement of the dielectric breakdown strength in the triple-layered film. The simulation results well matched the experimental data, indicating that controlling the volume ratio and relative dielectric constant of each layer in the triple-layered film is an effective approach to enhancing dielectric breakdown strength. This concept is considered promising for developing dielectric materials that enable a size reduction of film capacitors.
LFP batteries are widely used in energy storage stations and electric vehicles, but their related fire incidents have not been remediated. In this paper, the TR/TRP characteristics of LFP batteries/modules under different heat dissipation conditions are investigated through experiments and simulations. In addition, the TRP behaviour of large-capacity prismatic LFP modules under different SOCs and TR trigger modes is investigated in detail. It is found that the heat dissipation significantly affects the maximum TR temperature of the LFP single battery under overheating and whether TR occurs under overcharging. Besides, whether improving the convection coefficient can prolong the TRP time of the LFP module under overheating is influenced by the thermal resistance value between adjacent batteries. Furthermore, the TRP behaviour of the LFP module is significantly influenced by the SOC and TR trigger mode. 100% SOC LFP modules have the most intense TRP behaviour under overheating, with the TRP time increasing from 140 s to 644 s as the battery SOC drops from 100% to 80%, and TRP being blocked as the battery SOC drops to 50%. The LFP module however does not undergo TRP under overcharging even in an open environment at 80 °C.
Environmental degradation and energy shortages are becoming increasingly important as science and technology advance. Here, we review the photocatalytic approach of functionalized carbon quantum dots (CQDs) along with their up-converted photoluminescence behaviour, as well as their photoinduced electron transfer capabilities, opening a new path to effective metal-free photocatalyst. In this article, we are focusing on the recent invention of CQDs and CQD-based photocatalyst for environmental remediation such as dye degradation, CO2 conversion, and water splitting along with the categorization and synthesis of CQDs-derived photocatalysts, and applications for environmental concerns. Although it is essential to incorporate multiple perspectives, since CQDs and CQD-derived photocatalysts have varied perspectives to tackle unique environmental applications, our analysis is expected to offer additional details on CQD synthesis methods, tuning photocatalytic properties of CQDs with surface groups, and the mechanism of degradation of CQDs and CQD-based photocatalysts.