Selection of Planar Chiral Conformations between Pillar[5,6]arenes Induced by Amino Acid Derivatives in Aqueous Media

Chiral α-amino acids play critical roles in the metabolic process in nearly all life forms. So far, chiral recognition of α-amino acids has mainly focused on the determination of l /d enantiomers. Herein, selection of planar chiral conformations between water-soluble pillar[5]arene WP5 and pillar[6]arene WP6 was observed due to α-side chain or ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides binding with WP5 and WP6 , respectively. Therefore, α-side chain and ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides were recognized by observing the induced CD signal and its inversion. This is a rare example of being able to detect the chiral region around α-carbon of a chiral α-amino acid molecule.     

A fluorescent chemosensor for Cu2+ ions and its application in cell imaging

A new on-off fluorescent probe 1 for Cu²⁺ based on Schiff base compound was designed and synthesized by one-step reaction. The single probe 1 exhibited strong green fluorescence emission. A fluorescence quenching effect and faint color change were observed as soon as the Cu²⁺ was added to the probe system in H₂O/EtOH (v/v = 8:2, HEPES buffer, 0.05 M, pH = 7.4) solution. Other common metal cations did not cause the changes in the fluorescence and color of the probe 1. The optical properties were studied by the fluorescence emission and UV–Vis spectra. Meanwhile, the geometry optimizations of probe 1 and the [1-Cu²⁺] coordination complexes were also carried out by DFT using the Gaussian 09 program, in which the B3LYP function was used. Based on experimental measurement and theoretical analysis, we can know that the combination ratio of the probe and Cu²⁺ is 2:1 and the limit of detection (LOD) is as low as 5.3 × 10^?9 M Besides, the probe 1 was also used to analyze the Cu²⁺ in living cells.     

Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

In this letter, we discuss the increase in the average cluster size by lowering the stagnation temperature of the methane （CH4） gas. The Coulomb explosion experiments are conducted to estimate the cluster size and the size distribution. The average CH4 cluster sizes Nay of 6 230 and 6 580 are acquired with the source conditions of 30 bars at 240 K and 60 bars at 296 K, respectively. Empirical estimation suggests a five-fold increase in the average size of the CH4 clusters at 240 K compared with that at room temperature under a backing pressure of 30 bars. A strong nonlinear Hagena parameter relation （Г^＊∝ T0^-3.3） for the CH4 clusters is revealed. The results may be favorable for the production of large-sized clusters by using gases at low temperature and high back pressures.     

Difluorocarbene-Induced Ring-Opening Difluoromethylation-Halogenation of Cyclic (Thio)Ethers with TMSCF2X (X=Br,Cl)**

The ring-opening difluoromethylation-halogenation of cyclic (thio)ethers is reported through a simple strategy relying on carbon-chalcogen bond activation with difluorocarbene. The reaction proceeds through in situ protonation of the previously little-known difluoromethylene oxonium or sulfonium ylide intermediate followed by ring-opening with halide ion to afford halogenated acyclic difluoromethyl (thio)ethers that can then be employed for further elaboration. TMSCF₂X (X=Br, Cl) are unique reagents to achieve this synthetic purpose, which serve as both the difluorocarbene source and the halide ion source.     

Aggregation-Induced Generation of Reactive Oxygen Species: Mechanism and Photosensitizer Construction

Luminogens with aggregation-induced emission (AIEgens) have been widely applied in the field of photodynamic therapy. Among them, aggregation-induced emission photosensitizers (AIE–PSs) are demonstrated with high capability in fluorescence and photoacoustic bimodal imaging, as well as in fluorescence imaging-guided photodynamic therapy. They not only improve diagnosis accuracy but also provide an efficient theranostic platform to accelerate preclinical translation as well. In this short review, we divide AIE–PSs into three categories. Through the analysis of such classification and construction methods, it will be helpful for scientists to further develop various types of AIE–PSs with superior performance.     

Crosslinked polyaniline nanorods coupled with molybdenum disulfide on functionalized carbon cloth for excellent electrochemical performance

Journal of Solid State Electrochemistry - In this work, the binary nanocomposite of crosslinked polyaniline nanorods (CPANINRs) and molybdenum disulfide (MoS2) is first synthesized by in situ...     

Heterobimetallic Cluster-Based Coordination Polymers: Assembly,Structures and Third-Order Nonlinear Optical Properties

Reactions of (NH₄)₂WS₄ with CuCN, CuCN/1,2-bis(4-pyridyl)propane (bppa) or [Cu(MeCN)₄]PF₆/bppa under different reaction conditions afforded a set of two- or three-dimensional W/Cu/S cluster-based coordination polymers including {[Et₄N]₂[WS₄Cu₄(μ-CN)₂(μ-I)₂]}_n ( 1 ), [WS₄Cu₄(μ-CN)₂(bppa)₂]_n ( 2 ) and {[WS₄Cu₄(bppa)₄](PF₆)₂}_n ( 3 ), respectively. Compound 2 can be readily formed from reaction of 1 with bppa under solvothermal conditions. Compounds 1 and 2 feature two-dimensional networks with a “sql” topology, while 3 possesses a two-fold interpenetrated three-dimensional net with a rare “reo” topology. Compounds 1 – 3 in DMF exhibited different third-order nonlinear optical responses, and they all showed a reverse saturable absorption while 2 held a strong self-focusing effect.     

Potential Role of Melatonin as an Adjuvant for Atherosclerotic Carotid Arterial Stenosis

Carotid artery stenosis (CAS) is an atherosclerotic disease characterized by a narrowing of the artery lumen and a high risk of ischemic stroke. Risk factors of atherosclerosis, including smoking, hypertension, hyperglycemia, hyperlipidemia, aging, and disrupted circadian rhythm, may potentiate atherosclerosis in the carotid artery and further reduce the arterial lumen. Ischemic stroke due to severe CAS and cerebral ischemic/reperfusion (I/R) injury after the revascularization of CAS also adversely affect clinical outcomes. Melatonin is a pluripotent agent with potent anti-inflammatory, anti-oxidative, and neuroprotective properties. Although there is a shortage of direct clinical evidence demonstrating the benefits of melatonin in CAS patients, previous studies have shown that melatonin may be beneficial for patients with CAS in terms of reducing endothelial damage, stabilizing arterial plaque, mitigating the harm from CAS-related ischemic stroke and cerebral I/R injury, and alleviating the adverse effects of the related risk factors. Additional pre-clinical and clinical are required to confirm this speculation.