Luminescent Nanofibers Fabricated from Phenanthroimidazole Derivatives by Organogelation: Fluorescence Response towards Acid with High Performance

Nanofibers based on phenanthroimidazole derivatives PCC , PDC , and PSC were fabricated by organogelation processes, and their fluorescence sensory properties towards acid were investigated. It was found that the emission of PCC in the nanofiber‐based film could be quenched significantly upon exposure to gaseous TFA due to the formation of protonated PCC , in which ICT (intramolecular charge transfer) would occur. On the other hand, TFA vapor led to the emitting colors of PDC and PSC in the nanofiber‐based films to turn to yellow and green from sky blue and blue, respectively. Additionally, we found that the decay times of PCC were 0.1 s and 1.9 s in probing the saturated vapor of TFA in nanofiber‐based film and in spin‐coated film, respectively. The results suggested that the high surface‐to‐volume ratio and large interspace in the nanofiber‐based networks favored the enhanced adsorption, accumulation, and diffusion of gaseous molecules, resulting in such a high performance.     

Four Metal Complexes Based on Bulky Imidazole Ligands: Solvothermal Syntheses,Crystal Structures,and Fluorescence Properties

In order to explore the influences of (de‐)protonation of the imidazole ring on the structural diversity of the resulting complexes, the imidazole‐based ligands 4, 5‐diphenylimidazole (Hdpi) and 1H‐phenanthro[9, 10‐d]imidazole (Hpi) were utilized as bulky building blocks to construct four complexes by solvothermal reactions, i.e. [Ag(Hdpi)₂](NO₃) · (H₂O) ( 1 ), [Cu(dpi)]_∞ ( 2 ), [Cu(Hpi)(NO₃)]_∞ ( 3 ), and [(H₂pi)(NO₃)] · H₂O ( 4 ). In complex 1 , two Hdpi ligands adopt a monodentate pattern and coordinate with one Ag^I ion to form a mononuclear unit, which is further connected by hydrogen bonds into a 1D supramolecular helix. The deprotonated dpi ligand of 2 acts in bidentate mode, and bridges Cu^I ions to afford a 1D chain. In 3 , the NO₃^– ion, acts as a monodentate bridging ligand and joins Cu^I ions to generate a 1D chain. The Hpi ligand employs a monodentate mode to bond with Cu^I ions of the 1D chain. 4 is protonated and two H₂pi nitrogen atoms are free of coordination. Interestingly, hydrogen bonds among the NO₃^– ion, the H₂pi ligand, and the water molecule yield a macro ring R⁴₄(14). The resulting structural diversity reveals that the (de‐)protonation of imidazole ring directly steers the coordination number of ligand, and thus causes a significant effect on the structure, especially the dimensionality. Furthermore, the solid‐state fluorescence properties of the free ligands and compounds 1 – 4 were studied at room temperature.     

不同碱处理制备多级孔HZSM-5催化剂及噻吩烷基化性能研究

用Na₂CO₃、TPAOH和TPA⁺/CO₃^2-混合碱分别处理HZSM-5分子筛,采用FT-IR、XRD、XRF、N₂吸附脱附、SEM、NH₃-TPD及Py-FTIR表征手段对各类碱处理前后的HZSM-5分子筛进行表征。结果表明,3种类型的碱处理HZSM-5分子筛后,均能形成微孔-介孔多级孔道的HZSM-5(A)催化剂,并能调变催化剂的酸性,其中,TPA⁺/CO₃^2-混合碱处理得到的HZSM-5(TPA⁺/CO₃^2-)催化剂,比表面积最大,介孔数量最多。在小型固定床反应器上,考察了HZSM-5和HZSM-5(A)催化剂的噻吩烷基化性能,结果表明,HZSM-5(TPA⁺/CO₃^2-)催化剂因为具有适当的多级孔孔道和较多的B酸中心而表现出较高的噻吩转化率和1-己烯对噻吩的选择性。     

激光烧蚀-多接收电感耦合等离子体质谱测定铀颗粒物中铀全同位素比值

建立了铀颗粒物中铀全同位素比值的分析方法,采用双面胶带装载铀颗粒物样品,优化激光烧蚀-多接收电感耦合等离子体质谱的运行参数,用标准样品交叉法校正质量分馏和探测器检测效率,测定了粒径几十微米的铀标准物质CRM124-1、GBW04234和GBW04238中铀全同位素比值.本方法对铀颗粒物中235U/238U、234 U/235U和236 U/235U测量的相对实验标准不确定度分别小于0.050％,1.7％和1.8％,测量结果与参考值在不确定度范围内符合.研究表明,本方法可快速、准确、高精度地测定铀颗粒物中铀全同位素比值.     

Synthesis and Crystal Structure of Sm Cu7.73In3.27: a New 3D Framework Based on [Cu5In4M4]（M=Cu/In） Cluster

A new intermetallic compound, SmC u7.73In3.27, has been synthesized by solid-state reaction of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction study. SmC u7.73In3.27 crystallizes in tetragonal space group P4/mbm with a = 8.6213(4), c = 10.2538(9), V = 762.13(8) A3, Z = 4, Mr = 1018.90, Dc = 8.880 g/cm3, μ =38.244 mm-1, F(000) = 1789, and the final R = 0.0374 and w R = 0.0836 for 514 observed reflections with I 2σ(I). The structure of SmC u7.69In3.31 belongs to a new structure type and features a three-dimensional(3D) [Cu5In2M4](M = Cu/In) framework composed of [Cu5In4M4] clusters interconnected via sharing In atoms as well as Cu–In and In–In bonds. The Sm atoms are located in the one-dimensional(1D) tunnels along the c-axis. The structural relationship of the title compound with other similar Sm-Cu-In phases was also studied. Band structure calculations based on Density Functional Theory(DFT) method indicate that SmC u7.69In3.31 is metallic.     

Structure Modification Function of g‐C3N4 for Al2O3 in the In Situ Hydrothermal Process for Enhanced Photocatalytic Activity

Heterojunctions of g‐C₃N₄/Al₂O₃ (g‐C₃N₄=graphitic carbon nitride) are constructed by an in situ one‐pot hydrothermal route based on the development of photoactive γ‐Al₂O₃ semiconductor with a mesoporous structure and a high surface area (188 m²g^?1) acting as electron acceptor. A structure modification function of g‐C₃N₄ for Al₂O₃ in the hydrothermal process is found, which can be attributed to the coordination between unoccupied orbitals of the Al ions and lone‐pair electrons of the N atoms. The as‐synthesized heterojunctions exhibit much higher photocatalytic activity than pure g‐C₃N₄. The hydrogen generation rate and the reaction rate constant for the degradation of methyl orange over 50 % g‐C₃N₄/Al₂O₃ under visible‐light irradiation (λ>420 nm) are 2.5 and 7.3 times, respectively, higher than those over pristine g‐C₃N₄. The enhanced activity of the heterojunctions is attributed to their large specific surface areas, their close contact, and the high interfacial areas between the components as well as their excellent adsorption performance, and efficient charge transfer ability.     

A Highly Efficient Chirality Switchable Synthesis of Dihydropyran‐Fused Benzofurans by Fine‐Tuning the Phenolic Proton of β‐Isocupreidine (β‐ICD) Catalyst with Methyl

A highly enantioselective β‐isocupreidine (β‐ICD) catalyzed synthesis of dihydropyran‐fused benzofurans through [4+2] cycloaddition of allenoates and benzofuranone alkenes was developed. Switchable chirality inversion of cycloaddition products was achieved by replacing the phenolic proton of the catalyst with a methyl, demonstrating an amazing effect of minimal structural variation on inverting enantioselectivity. DFT calculations were utilized to elucidate the origin of the observed phenomena. Computation also provided a clue for a rational design in which the multi‐hydrogen bond with the alcohol additive was found to improve the enantioselectivity of the cycloaddition. Finally, the substrate scope was examined, in which a number of functionalized dihydropyran‐fused benzofurans could be obtained in high yields (up to 97 %) with very good regio‐ (>20:1) and enantioselectivities (up to 98:2 e.r.).     

Strong Fluorescent Smart Organogel as a Dual Sensing Material for Volatile Acid and Organic Amine Vapors

An L ‐phenylalanine derivative ( C12PhBPCP ) consisting of a strong emission fluorophore with benzoxazole and cyano groups is designed and synthesized to realize dual responses to volatile acid and organic amine vapors. The photophysical properties and self‐assembly of the said derivative in the gel phase are also studied. C12PhBPCP can gelate organic solvents and self‐assemble into 1 D nanofibers in the gels. UV/Vis absorption spectral results show H‐aggregate formation during gelation, which indicates strong exciton coupling between fluorophores. Both wet gel and xerogel emit strong green fluorescence because the cyano group suppresses fluorescence quenching in the self‐assemblies. Moreover, the xerogel film with strong green fluorescence can be used as a dual chemosensor for quantitative detection of volatile acid and organic amine vapors with fast response times and low detection limits owing to its large surface area and amplified fluorescence quenching. The detection limits are 796 ppt and 25 ppb for gaseous aniline and trifluoroacetic acid (TFA), respectively.