Efficient approach to allylated quinolines via palladium-catalyzed cyclization–allylation of 1-azido-2-(2-propynyl) benzenes with allyl methyl carbonate

The palladium-catalyzed cyclization–allylation reaction of ortho-azido propynylbenzenes 1 and allyl methyl carbonate 2d gives the corresponding allylated quinolines in moderate to good yields. The reaction of 1-azido-2-(2-propynyl)benzene 1a proceeds smoothly with 10 mol % Pd(PPh₃)₄ and 5 equiv K₃PO₄ or NaOAc in DMF at 100 °C to afford 3,4-diallylquinoline 3a in 69% yield in the case of R² = H and 3-allylquinoline 4 in 67% yield in the case of R² ≠ H.     

Synthesis of cholate-based pyridinium receptor and its recognition toward l-tryptophan

Four cholate-based pyridinium compounds were synthesized and their binding abilities toward unmodified amino acids were investigated by UV spectroscopy and fluorescence emission spectroscopy. Studies revealed that the recognition process involved hydrogen bonding, electrostatic force, and π–π interaction. The receptor 4a was found to recognize l-tryptophan specifically, and the complex was studied by ¹H NMR spectroscopy. The receptors 4b and 4c showed very little recognition ability toward l-tryptophan, indicating the important role of the benzyl group at pyridinium ring.     

Self‐Assembly of Five 8‐Hydroxyquinolinate‐Based Complexes: Tunable Core,Supramolecular Structure,and Photoluminescence Properties

Five new Zn^II complexes, namely [Zn₃(L)₆] ( 1 ), [Zn₂(Cl)₂(L)₂(py)₂] ( 2 ), [Zn₂(Br)₂(L)₂(py)₂] ( 3 ), [Zn(L)₂(py)] ( 4 ), and [Zn₂(OAc)₂(L)₂(py)₂] ( 5 ), were prepared by the solvothermal reaction of ZnX₂ (X^?=Cl^?, Br^?, F^?, and OAc^?) salts with a 8‐hydroxyquinolinate ligand (HL) that contained a trifluorophenyl group. All of the complexes were characterized by elemental analysis, IR spectroscopy, and powder and single‐crystal X‐ray crystallography. The building blocks exhibited unprecedented structural diversification and their self‐assembly afforded one mononuclear, three binuclear, and one trinuclear Zn^II structures in response to different anions and solvent systems. Complexes 1 – 5 featured four types of supramolecular network controlled by non‐covalent interactions, such as π???π‐stacking, C? H???π, hydrogen‐bonding, and halogen‐related interactions. Investigation of their photoluminescence properties exhibited disparate emission wavelengths, lifetimes, and quantum yields in the solid state.     

Synthesis and Chromatographic Evaluation of Perfluorooctyl Stationary Phase for Separation of Basic Compounds

Fluorinated stationary phases provide unique separation effect on basic compounds, due to the fluorine atoms, and pentafluorophenyl stationary phases (PFPs) are the most widely used. Considering that some fluoroalkyls have higher fluorine contents than PFPs do, it is speculated that fluoroalkyl stationary phases should have potential new applications. Herein, we synthesized a silica-based stationary phase bonding perfluoroctyl (FC8) proved by characterization through elemental analysis and solid-state ¹³C cross-polarization/magic-anglespinning nuclear magnetic resonance. The chromatographic behavior of the stationary phase was evaluated with test compounds. In addition, to further study the applicability of FC8 materials, Corydalis decumbens (Thunb.) Pers. fraction, considered as a challenging medicine on reversed-phase chromatography columns, was chosen as a test sample. Results demonstrated that the FC8 stationary phase had better and more satisfactory separation performance than the PFP stationary phase on basic compounds.

     

嵌段共聚物薄膜快速自组装方法

嵌段共聚物 (BCP) 薄膜可通过不同的退火方法诱导其微相分离,从而获得大面积圆柱状、层状和球状等纳米图案。这些长程有序的纳米结构形态,已经广泛应用在纳米光刻和电子器件等多个领域中。目前,有效且快速的退火方法仍然是BCP薄膜自组装技术中的研究热点。本文首先介绍了制备BCP薄膜纳米结构图案常用的退火技术,然后综述了三种新型快速退火技术,最后分析总结了这些退火技术的优缺点。     

Single-crystal structure of two-dimensional organic framework based on donor-acceptor interactions with charge-transfer effect

Two charge-transfer single crystals induced by donor-acceptor interactions were obtained. The presence of different solvent molecules led to 1D(linear) or 2D self-assembly modes. More interestingly, the 2 D organic framework, a layer-by-layer 2D organic framework single crystal, showed a stronger charge-transfer effect than the 1D cocrystal.     

Synthesis of Fluorescent Carbon Dots and Their Application in Ascorbic Acid Detection

Water-soluble fluorescent carbon dots (CDs) were synthesized by a hydrothermal method using citric acid as the carbon source and ethylenediamine as the nitrogen source. The repeated and scale-up synthetic experiments were carried out to explore the feasibility of macroscopic preparation of CDs. The CDs/Fe³⁺ composite was prepared by the interaction of the CDs solution and Fe³⁺ solution. The optical properties, pH dependence and stability behavior of CDs or the CDs/Fe³⁺ composite were studied by ultraviolet spectroscopy and fluorescence spectroscopy. Following the principles of fluorescence quenching after the addition of Fe³⁺ and then the fluorescence recovery after the addition of asorbic acid, the fluorescence intensity of the carbon dots was measured at λex = 360 nm, λem = 460 nm. The content of ascorbic acid was calculated by quantitative analysis of the changing fluorescence intensity. The CDs/Fe³⁺ composite was applied to the determination of different active molecules, and it was found that the composite had specific recognition of ascorbic acid and showed an excellent linear relationship in 5.0–350.0 μmol·L⁻¹. Moreover, the detection limit was 3.11 μmol·L⁻¹. Satisfactory results were achieved when the method was applied to the ascorbic acid determination in jujube fruit. The fluorescent carbon dots composites prepared in this study may have broad application prospects in a rapid, sensitive and trace determination of ascorbic acid content during food processing.     

Methane adsorption properties of N-doped graphdiyne: a first-principles study

Structural Chemistry - N-doped graphdiyne (N-graphdiyne) is a new kind of alkynyl carbon material whose structure resembles graphdiyne. This study describes the Mn-modified N-graphdiyne...     

Effect of Protective Measures on Eye Exposure to Solar Ultraviolet Radiation

In this study, ocular biologically effective exposure to solar ultraviolet radiation (UVBE) is investigated with six kinds of sun protective measures (spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol). Ocular UV exposure measurements were performed on manikins during the summer period in Shenyang city (41.64° N, 123.50° E, 66 m a.s.l.), China. The measurements include the ocular UV exposure of an unprotected eye and the ambient UV as a control concurrently. Based on the relative spectral weighting factors of the International Commission on Non‐Ionizing Radiation Protection (ICNIRP), the ocular biologically effective UV is calculated and compared with the 8‐h exposure limits of ICNIRP (30 J m^?2). The UV index (UVI) of the measurement days is 0–8, and the 8‐h (8:00–16:00 China Standard Time, CST) cumulated UVBE of the unprotected eye is 452.0 J m^?2. The 8‐h cumulated UVBE of the eye with spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol are 364.2, 69.1, 51.4, 49.0, 56.8 and 110.2 J m^?2, respectively. Importantly, it should be noted that the eye could be exposed to risk despite protective measures. The 8‐h cumulated UVBE of the eye with protection is ca 1.6–15.1 times the exposure limit, respectively. As indicated in the present study, during summer months, high exposure to the sun for more than 30 min without eye protection and more than 1 h with eye protection is not advisable. The protection measures could effectively reduce the UVBE reaching the eye, yet there is still a high degree of risk when compared with the ICNIRP 8‐h exposure limits.     

Determination of PEGylation homogeneity of polyethylene glycol-modified canine uricase

Polyethylene glycol-modified canine uricase (PEG-UHC) was prepared by modifying the ε-amino group of lysine residues on the canine uricase (UHC) protein to near-saturation with 5 kDa monomethoxyl-polyethylene glycol succinimide (mPEG-SPA-5k). In order to accurately determine the PEGylation uniformity of PEG-UHC, CZE, 3–8% gradient gel SDS-PAGE, and imaging CIEF (iCIEF) analyses were compared. CZE could not effectively separate PEG-UHC proteins with different degrees of modification, 3–8% gradient gel SDS-PAGE could separate PEG-UHC into seven gel bands; however, most of the gel bands were smeared or blurred, and the separation of PEG-UHC samples by iCIEF was significantly better than that by 3–8% gradient gel SDS-PAGE. Under denatured conditions, iCIEF separated 12 pI peaks, and could also accurately quantify the relative monomer PEG-UHC content. More than 85% of the total monomeric PEG-UHC was conjugated with 7–12 PEG molecules; of this 85%, approximately 40% was conjugated with 9–10 PEG molecules. These results demonstrated that iCIEF exhibits good potential for determining the PEGylation homogeneity of PEGylated protein drugs.