Near-infrared phosphorescence emission of three-fold interpenetrated MOF based on 1,4-bis(imidazole-1-ylmethyl)benzene: Syntheses, structure and photoelectron performance

Stable Nickel-Based Metal–Organic Framework Containing Thiophene/Diimidazole Units for Effective Near-Infrared Photothermal Conversion

Herein, a new Ni-based metal–organic framework (MOF, 1) bearing highly structural stability is synthesized by the reaction of utilizing a rigid and functionalized linker, 2,6-bis(pyridin-4-yl)-1,7-dihydrobenzo[1,2-d:4,5-d′]diimidazole (BBI4PY), in combination with Ni(NO3)2·6H2O and dibenzo[b,d]thiophene-3,7-dicarboxylic acid 5,5-dioxide (L1) under solvothermal conditions. The crystal structure of complex 1 is determined by single-crystal X-ray diffraction and is demonstrated to be a two-dimensional layered structure. In addition, PXRD, IR, TGA and UV/Vis-NIR spectra are also tested carefully to explore the solid structure of this complex. Remarkably, although no significant accumulation effect could be observed between the two-dimensional layers, a stacking interaction between DMF solvent molecules and ligand L1 could be found, which might promote non-radiative transitions and trigger obvious near-infrared photothermal conversion. Under 660 nm laser (0.6 W cm−2) illumination, the temperature of complex 1 increased rapidly from room temperature to 45.2 °C, with good thermal stability and cycle durability. Its photothermal conversion efficiency could reach 10.75%. This work provides an efficient way for assessing the promise of materials in the field of photothermal therapy.

Size-Induced Highly Selective Synthesis of Organometallic Rectangular Macrocycles and Heterometallic Cage Based on Half-Sandwich Rhodium Building Block

The controlled synthesis of organometallic supramolecular macrocycles cages remains interesting and challenging work in the field of supramolecular chemistry. Here, two tetranuclear rectangular macrocycles and an octuclear cage were designed and synthesized utilizing a rigid and functionalized pillar linker, 2,6-bis(pyridin-4-yl)-1,7-dihydrobenzo [1,2-d:4,5-d']diimidazole (BBI4PY) based on three half-sandwich rhodium building blocks bearing different sizes. X-ray crystallography in combination with 1H NMR spectroscopy elucidated that the two building blocks with shorter spacers only result in rectangular macrocycles. However, the building block of bulkier size to avoid the π-π stacking interactions between two ligands BBI4PY led to the formation of an octuclear cage complex. The latter cage contains two types of metal ions, namely Rh3+ and Cu2+, showing significant characteristics of heterogeneous metal-assembling compounds. In addition, the cage accommodates two free isopropyl ether solvent molecules, thus displaying host-guest behavior.

Synthesis and structure of a zinc(II) coordination polymer assembled with 5-(3-carboxybenzyloxy)isophthalic acid and 1,2-bis(4-pyridyl)ethane

A zinc(II) coordination polymer [Zn(cyip)(bpe)] n (1), (cyipH2 = 5-(3-carboxybenzyloxy)-isophthalic acid, bpe = 1,2-bis(4-pyridyl)ethane), has been synthesized under hydrothermal conditions. Its structure was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis and IR spectra. Complex 1 crystallizes in the monoclinic space group I2/a. In 1, the [cyip]2– ligand bridges the Zn(II) cations to form infinite chains, which are connected through O–H···O hydrogen bonds into layers in the form of 2-fold interpenetrated nets.

Stable Zinc-Based Metal-Organic Framework Photocatalyst for Effective Visible-Light-Driven Hydrogen Production

Herein, a new Zn-MOF material, [Zn(L1)(L2)], 1, was built successfully through a one-pot solvothermal method. The 3D MOF structure was determined by Single X-ray diffraction analysis, IR, and elemental analysis. A series of PXRD tests of 1 after being immersed in different solvents and pH solutions demonstrated the good stability of 1. Interestingly, this material displayed high catalytic activity for the visible-light-driven hydrogen generation under the illumination of white LED in pure water or a mixture of DMF and H₂O without additional photosensitizers and cocatalysts. Besides, the studies also showed that the catalytic activity changed constantly as well as the solvent ratio adjustment of DMF and H₂O from 4:6 to 2:8. Additionally, the catalytic activity reached the best value (743 μmol g^-1 h^-1) when the solvent ratio was 4:6. The heterogeneous nature and recyclability of the MOF catalyst, as well as several factors that affect the catalytic activity, were investigated and described in detail. Moreover, the photocatalytic mechanism for the hydrogen generation of 1 was also proposed based on the fluorescence spectra and UV-vis absorption.

A (4,4)-connected zinc(II) coordination polymer constructed with the flexible 2-carboxy phenoxyacetate ligand: synthesis, conformation alteration and fluorescent properties

A new binary ZnII coordination polymer, [Zn(2-cpa)(H2O)] n (2D-Zn) has been prepared by a 120 °C hydrothermal reaction of zinc(II) sulfate heptahydrate and 2-carboxy phenoxyacetic acid (2-H2cpa) in the presence of potassium hydroxide. Single-crystal X-ray diffraction analysis shows that the ZnII ion is located in a deformed ZnO6 octahedron bonded by one water and three 2-carboxy phenoxyacetate (2-cpa) ligands. The 2-cpa exhibits pentadentate double bridging chelate-μ 3 coordination mode and connects adjacent ZnII ions to generate a corrugated (4,4)-connected layer structure. The structures, conformation of 2-cpa and photoluminescence spectra for 2D-Zn have been carefully analyzed and compared with its two closely related compounds ̶ 1D [Zn(2-cpa)(H2O)] n (1D-Zn) and mononuclear [Zn(2-cpa)(H2O)3] (0D-Zn). The results showed that the conformation of 2-cpa in 2D-Zn has the maximum alteration and the corresponding fluorescence emission peak of 2D-Zn has the largest red-shift of 62 nm compared with that of free 2-H2cpa.