Molecular anchor Cu-S formed on a thiophene mediated Si(111)-(7x7) surface

Thiophene molecule selectively binds to the adjacent adatom-rest atom pair on the Si(111)-(7x7) surface through its alpha-carbon atoms, leading to the covalent attachment of a C-S-C linkage and remaining C=C (beta-carbon) bond onto the surface. Photoemission studies show that Cu atom readily adsorbs onto the S atom of the functional group to form the Cu-S molecular anchor in two forms: one points away from the thiophene C=C group; the other points toward the C=C group.     

LC–ESI-MS Determination of Hydroxycamptothecin in Rat Plasma

A rapid and sensitive method using liquid chromatography with electrospray ionization mass spectrometric detection (LC–ESI-MS) was developed and validated for the determination of hydroxycamptothecin in rat plasma. Plasma samples were extracted with ether and separated on a C₁₈ column interfaced with a single quadrupole mass spectrometer, with mobile phase consisting of 0.1% formic acid–methanol (45:55, v/v). Detection was carried out by positive electrospray ionization (ESI) in selected ion recording (SIR) mode at m/z 321 and 305 for hydroxycamptothecin and camptothecin (internal standard), respectively. The linearity was obtained ranged from 2.5 to 1,000 ng mL^?1 and the lower limit of quantification (LLOQ) was determined to be at 2.5 ng mL^?1. The intra- and inter-day precision (%RSD) was less than 5.5% and accuracy (% RE) ranged from 3.8 to 5.3%. This method was applied successfully to a preliminary pharmacokinetic study following the intravenous administration of hydroxycamptothecin to rats.     

Immobilization of penicillin G acylase on poly[(glycidyl methacrylate)-co-(glycerol monomethacrylate)]-grafted magnetic microspheres

Poly[(glycidyl methacrylate)-co-(glycerol monomethacrylate)]-grafted magnetic microspheres were prepared by graft random copolymerization via ATRP from polymer microspheres with dispersed Fe(3)O(4) nanoparticles. Penicillin G acylase (PGA) was immobilized onto the polymer brush-grafted magnetic microspheres. The immobilized PGA prepared with initial glycidyl methacrylate/glycerol monomethacrylate ratios of 40/60 to 60/40 possessed higher catalytic activity than that prepared with higher proportions of glycidyl methacrylate in the initial monomer mixture. The immobilized PGA showed high thermal stability and enhanced tolerability to the pH variance.     

Syntheses,Crystal Structures and Luminescent Properties of Three Inorganic‐Organic Hybrid Frameworks Constructed from 4,5‐Imidazoledicarboxylate

Three inorganic‐organic hybrid frameworks [Mn(HIMDC)(4,4′‐bipyo)_0.5(H₂O)]_n (1) , [Cd(H₂IMDC)₂(2,2′‐bipyo)] (2) and [Ca(HIMDC)(H₂O)₂·H₂O]_n (3) (H₃IMDC = 4,5‐imidazoledicarboxylate; 4,4′‐bipyo = 4,4′‐bipyridine‐N,N′‐dioxide; 2,2′‐bipyo= 2,2′‐bipyridine‐N,N′‐dioxide) have been hydrothermally synthesized and characterized by the elemental analyses, IR spectra, TG analysis and the single crystal diffraction. Both compounds 1 and 3 exhibit 2D layers while 2 is a monomer. It is noteworthy that compound 2 exhibits strong fluorescent emission in the solid state at room temperature.     

吡嗪类碳酰肼化合物与CT-DNA相互作用及体外抑菌

以5-氯吡嗪-2-羧酸甲酯和水合肼为原料,经亲核取代和脱水缩合反应合成了3种新型吡嗪类碳酰肼化合物C13H14N6O(a)、C13H14N6O2(b)和C12H12N6O2(c)。采用元素分析与核磁共振氢谱对化合物a~c进行了表征,结果表明合成的产物即为目标化合物。通过溶剂挥发法培养得到了化合物a的单晶并利用X-射线单晶衍射测定化合物a的晶体结构为单斜晶系。根据紫外-可见光谱可知,化合物a~c均以插入模式与CT-DNA作用。利用微量热实验测定了化合物a~c与CT-DNA的相互作用,发现反应过程放热,热效应ΔH依次为-5.77×103、 -5.50×103和-5.96×103 kJ·moL-1,反应时间均小于40 min。通过分子对接模拟计算明确了化合物a和b与DNA的具体结合位点包括A链DC4和DG5以及B链DC4、 DG5和DA6,化合物c与DNA的具体结合位点包括A链DC4和DG5以及B链DC4和DG5。采用牛津杯法测定了化合物a~c对枯草芽孢杆菌、金黄色葡萄球菌、铜绿假单胞菌以及大肠杆菌四种细菌的抑菌活性,结果表明化合物a~c均对铜绿假单胞菌表现出优于阳性对照组四环素的抑菌活性。     

Grain Boundary Electronic Insulation for High-Performance All-Solid-State Lithium Batteries

Sulfide electrolytes with high ionic conductivities are one of the most highly sought for all-solid-state lithium batteries (ASSLBs). However, the non-negligible electronic conductivities of sulfide electrolytes (≈10⁻⁸ S cm⁻¹) lead to electron smooth transport through the sulfide electrolyte pellets, resulting in Li dendrite directly depositing at the grain boundaries (GBs) and serious self-discharge. Here, a grain-boundary electronic insulation (GBEI) strategy is proposed to block electron transport across the GBs, enabling Li−Li symmetric cells with 30 times longer cycling life and Li−LiCoO₂ full cells with three times lower self-discharging rate than pristine sulfide electrolytes. The Li−LiCoO₂ ASSLBs deliver high capacity retention of 80 % at 650 cycles and stable cycling performance for over 2600 cycles at 0.5 mA cm⁻². The innovation of the GBEI strategy provides a new direction to pursue high-performance ASSLBs via tailoring the electronic conductivity.     

Enhanced Four-Electron Oxygen Reduction Selectivity of Clamp-Shaped Cobalt(II) Porphyrin(2.1.2.1) Complexes

The molecular structure, electrochemistry, spectroelectrochemistry and electrocatalytic oxygen reduction reaction (ORR) features of two Co^II porphyrin(2.1.2.1) complexes bearing Ph or F₅Ph groups at the two meso-positions of the macrocycle are examined. Single crystal X-ray analysis reveal a highly bent, nonplanar macrocyclic conformation of the complex resulting in clamp-shaped molecular structures. Cyclic voltammetry paired with UV/Vis spectroelectrochemistry in PhCN/0.1 M TBAP suggest that the first electron addition corresponds to a macrocyclic-centered reduction while spectral changes observed during the first oxidation are consistent with a metal-centered Co^II/Co^III process. The activity of the clamp-shaped complexes towards heterogeneous ORR in 0.1 M KOH show selectivity towards the 4e⁻ ORR pathway giving H₂O. DFT first-principle calculations on the porphyrin catalyst indicates a lower overpotential for 4e⁻ ORR as compared to the 2e⁻ pathway, consistent with experimental data.     

Precision Graphene Nanoribbon Heterojunctions by Chain-Growth Polymerization

Graphene nanoribbons (GNRs) are considered promising candidates for next-generation nanoelectronics. In particular, GNR heterojunctions have received considerable attention due to their exotic topological electronic phases at the heterointerface. However, strategies for their precision synthesis remain at a nascent stage. Here, we report a novel chain-growth polymerization strategy that allows for constructing GNR heterojunction with N=9 armchair and chevron GNRs segments ( 9-AGNR/cGNR ). The synthesis involves a controlled Suzuki–Miyaura catalyst-transfer polymerization (SCTP) between 2-(6′-bromo-4,4′′-ditetradecyl-[1,1′:2′,1′′-terphenyl]-3′-yl) boronic ester ( M1 ) and 2-(7-bromo-9,12-diphenyl-10,11-bis(4-tetradecylphenyl)-triphenylene-2-yl) boronic ester ( M2 ), followed by the Scholl reaction of the obtained block copolymer ( poly-M1/M2 ) with controlled M_n (18 kDa) and narrow Đ (1.45). NMR and SEC analysis of poly-M1/M2 confirm the successful block copolymerization. The solution-mediated cyclodehydrogenation of poly-M1/M2 toward 9-AGNR/cGNR is unambiguously validated by FT-IR, Raman, and UV/Vis spectroscopies. Moreover, we also demonstrate the on-surface formation of pristine 9-AGNR/cGNR from the unsubstituted copolymer precursor, which is unambiguously characterized by scanning tunneling microscopy (STM).     

Didepside Formation by the Nonreducing Polyketide Synthase Preu6 of Preussia isomera Requires Interaction of Starter Acyl Transferase and Thioesterase Domains

Orsellinic acid (OA) derivatives are produced by filamentous fungi using nonreducing polyketide synthases (nrPKSs). The chain-releasing thioesterase (TE) domains of such nrPKSs were proposed to also catalyze dimerization to yield didepsides, such as lecanoric acid. Here, we use combinatorial domain exchanges, domain dissections and reconstitutions to reveal that the TE domain of the lecanoric acid synthase Preu6 of Preussia isomera must collaborate with the starter acyl transferase (SAT) domain from the same nrPKS. We show that artificial SAT-TE fusion proteins are highly effective catalysts and reprogram the ketide homologation chassis to form didepsides. We also demonstrate that dissected SAT and TE domains of Preu6 physically interact, and SAT and TE domains of OA-synthesizing nrPKSs may co-evolve. Our work highlights an unexpected domain–domain interaction in nrPKSs that must be considered for the combinatorial biosynthesis of unnatural didepsides, depsidones, and diphenyl ethers.     

Chemical Communication and Protocell-Matrix Dynamics in Segregated Colloidosome Micro-Colonies

Despite an emerging catalogue of collective behaviours in communities of homogeneously distributed cell-like objects, microscale protocell colonies with spatially segregated populations have received minimal attention. Here, we use microfluidics to fabricate Janus-like calcium alginate hydrogel microspheres with spatially partitioned populations of enzyme-containing inorganic colloidosomes and investigate their potential as integrated platforms for domain-mediated chemical communication and programmable protocell-matrix dynamics. Diffusive chemical signalling within the segregated communities gives rise to increased initial enzyme kinetics compared with a homogeneous distribution of protocells. We employ competing enzyme-mediated hydrogel crosslinking and decrosslinking reactions in different domains of the partitioned colonies to undertake selective expulsion of a specific protocell population from the community. Our results offer new possibilities for the design and construction of spatially organized cytomimetic consortia capable of endogenous chemical processing and protocell-environment interactivity.