Yun-Shan Xue

A new Ni coordination polymer [Ni(MIP)(BMIOPE)]_n (1) was constructed (BMIOPE = 4,4′-bis(2-methylimidazol-1-yl)diphenyl ether, and H₂MIP = 5-methylisophthalic acid), possessing two-dimensional (2D) twofold parallel interwoven net structure with a 4⁴∙6² point symbol. Complex 1 has been successfully obtained based on mixed-ligand strategy. The fluorescence titration experiments revealed that complex 1 could act as multifunctional luminescent sensor to simultaneously detect UO₂²⁺, Cr₂O₇²⁻ and CrO₄²⁻, and NFT (nitrofurantoin). The limit of detection (LOD) values for complex 1 are 2.86 × 10⁻⁵, 4.09 × 10⁻⁵, 3.79 × 10⁻⁵ and 9.32 × 10⁻⁵ M for UO₂²⁺, Cr₂O₇²⁻, CrO₄²⁻ and NFT. The K_sv values are 6.18 × 10³, 1.44 × 10⁴, 1.27 × 10⁴ and 1.51 × 10⁴ M⁻¹ for NFT, CrO₄²⁻, Cr₂O₇²⁻ and UO₂²⁺. Finally, the mechanism of its luminescence sensing is studied in detail. These results manifest that complex 1 is a multifunctional sensor for sensitive fluorescent UO₂²⁺, Cr₂O₇²⁻, CrO₄²⁻ and NFT detection.

The flipped class model is applied to the teaching process of carbon group elements, which fully reflects the effective teaching of "student-oriented and teacher-led". The students complete the "learning first" according to their self-study task list before class. The class's QQ group, wechat group and other social softwares communicate and interact with teachers and students online, and the cloud class topic database is used to detect the feedback effect of learning first. In class, teachers collect the feedback information of students' "learning first", carefully design the teaching process of "fixed teaching" problem inquiry, and encourage students to participate actively. After class, teachers and students can further communicate and interact online. Students can conduct self-awareness, self-reflection, self-evaluation and self-regulation of the learned knowledge unit, complete knowledge construction and improve students' metacognitive ability. Keywords: Flipping class model; Mindmap; Elemental compounds; Inorganic chemistry DOI: 10.7176/JEP/14-18-05 Publication date:June 30^th 2023

By using a semi-rigid tripodal ligand 5-(4-carboxybenzyloxy)isophthalic acid (H₃L) and lanthanide metal ions (Nd³⁺, Tb³⁺), two novel lanthanide metal–organic frameworks, namely, {[Nd₂L₂(DMF)4] DMF}_n (1), and {TbL(DMF)(H₂O)}_n (2), were synthesized under mild solvothermal conditions and structurally characterized by X-ray single crystal diffraction. Compounds 1 and 2 are isostructural, in which L^3– ligands linked dinuclear lanthanide metal–carboxylate units to form non-interpenetrated 3D network with (3,6)-connected topology. Luminescent investigations reveal that compound 1 displays the near-infrared emission at room temperature, and compound 2 can be employed as selective probe for Cr₂O₇²⁻ anion in aqueous solution based on luminescence quenching. Moreover, compound 2 exhibits catalytic activity for cyclo-addition of CO₂ and epoxides under relatively mild conditions.