Structural extension of 2D complexes to 3D complexes and their applications

Abstract

Two-dimensional (2D) Cu-CP (Cu-CP = [Cu(pca) 2 • Hpca] n ) (1) with an interpenetrating double-layer structure was prepared using a hydrothermal method based on 4-picolinic acid (Hpca) ligand. Because 3d-4f metal-incorporated polyoxometalate (POM) materials have received increasing attention, the extension of Cu-CP from a 2D to a three-dimensional (3D) structure was achieved by adding H 4 SiW 12 O 40 and rare earth metal. Three isostructural 3D 3d-4f metal-incorporated POMs were obtained: Cu-Ln-CPs (Cu-Ln-CPs = [Ln 2 Cu (SiW 12 O 40 ) (Hpca) 4 (pca) 4 (H 2 O) 2 ]• (Hpca) 2 •(I 2 ) 0.5 , Ln = Sm (2), Gd (3), La (4)). The applications of these complexes in the fields of fluorescence and electrochemistry were explored. The results showed that the expanded structure of the complexes can realize the fluorescent sensing of Ni 2+ and Cr 3+ and the electrochemical sensing of nitrite.

3D Porous Metal–Organic Skeleton Based on Polyoxometalate Nanoclusters as an Anode in a Lithium-Ion Battery

“…Compared with the initial discharge capacity, the charge capacity of both of them is significantly reduced (812.5 and 501.8 mA h g –1 ), and this loss is irreversible, essentially owing to the generation of the SEI film. First, the Coulombic efficiencies of the two materials are 62.90 and 59.17%, respectively, which are higher than those of other reported lithium-ion battery materials. − It is noteworthy that the 0D basket POM ( BAS-11 ) has a higher reversible capacity than the Keggin and Dawson matrix, , which may be related to the more redox centers (Mo) in the basket skeleton and its unique cage structure. Therefore, the good electrochemical storage capacity of BAS-MOF-1 can be attributed to the strong redox ability of the basket POM, special interlayer structure, and multichannel stable structure. , The redox mechanism and XPS evidence are shown in Figure , S11.…”

“…19−27 Lan and co-workers develop diamondoid and zeolite-like POMOFs for LIBs with reversible capacities of 640 and 780 mAh g −1 after 100 and 200 cycles, respectively. 19−21 Sha and co-workers assembled many POMOFs with fancy structures, such as nanocage, calixarene, pillararene, cantane, carbene, and multifold helical cathode materials, 22−27 in which the capacity of the multifold helical POMOF, H 3 [Ag 27 (trz) 16 (H 2 O) 6 ][SiW 12 O 40 ] 2 •5H 2 O, is up to 1356 mAh g −1 . 25 Different types of POMs and diverse spatial structures of MOF determine their LIB performance.…”

“…Polyoxometalates (POMs) are suitable candidates for energy storage due to their electronic sponge characteristics, structural diversity, and electrochemical stability. − Since the Sonoyama group first attempted to use Keggin phosphomolybdate as the anode material for Li-ion batteries (LIBs), the related properties of many POM-based compounds have been intensively reported. − However, most POMs suffer from limited specific surface area, high solubility in electrolytes, and relatively weak conductivity, restricting their practical utilization in LIBs. Integration of POM units with metal–organic frameworks (MOFs) to form POM-based MOFs (POMOFs) is an effective method to get over the above defects. − POMOF materials possess improved specific surface area, enhanced stability, and accelerated electron conversion efficiency and exhibit excellent electrochemical storage performance due to their combination of the merits of MOF and POMs. Recently, several typical success examples have been reported in the field. − Lan and co-workers develop diamondoid and zeolite-like POMOFs for LIBs with reversible capacities of 640 and 780 mAh g –1 after 100 and 200 cycles, respectively. − Sha and co-workers assembled many POMOFs with fancy structures, such as nanocage, calixarene, pillararene, cantane, carbene, and multifold helical cathode materials, − in which the capacity of the multifold helical POMOF, H 3 [Ag 27 (trz) 16 (H 2 O) 6 ]­[SiW 12 O 40 ] 2 ·5H 2 O, is up to 1356 mAh g –1 .…”

One-Step Synthesis of Hollow CoS2 Spheres Derived from Polyoxometalate-Based Metal–Organic Frameworks with Peroxidase-like Activity

“…POMs have been used together with surfactants as a precursor to prepare materials with hollow morphologies . The introduction of POMs into the structure of MOFs generates polyoxometalate-based MOF materials (POMOFs). − POMOFs − act as precursors, providing a rich metal source, and the POMs are uniformly distributed in the framework to provide morphology modification. Thus, POMOFs are good candidates to be used as precursors and templates for the one-step preparation of hollow pure-phase CoS 2 .…”