Self-Assembly of Biarsenate Capped Keggin Arsenomolybdates with Tetravanadium Substitution for Photocatalytic Degradation of Organic Dyes

Abstract

Four new POMs biarsenate­(III) capped Keggin arsenomolybdates with tetravanadium­(IV) substituted (bix)­[H3As2 IIIAsVMo8V4 IVO40]­[Cu­(bix)]2·3H2O­(1), [{HAs2 IIIAsV Mo8V4 IVO40}­{Cu­(bib)}2]­[Cu­(bib)]2(2), [{As2 IIIAsVMo8V4 IVO40}­{Cu3(tib)2(H2O)2}] [Cu­(tib)­(H2O)]2·4H2O­(3), and [HAs2 IIIAsVMo8V4 IVO40]­[Cu2(bih)]2(4) (bix = 1,4-bis­(imidazol-1-ylmethyl) benzene; bib = 1,3-bis (imidazol-1-ylmethyl)­benzene; tib = 1,3,5-tris­(1-imidazolyl)­benzene; bih = 1,6-bis­(imidazol-1-ylmethyl)­hexane) were prepared. Compound 1 contains a {Cu­(bix)}2 fragment and [H3As2 IIIAsVMo8V4 IVO40]2– cluster, which form a 1D chain by Cu1···O6 3.215 Å. The {Cu­(bib)}2 chain threads the rectangular loop of other {Cu­(bib)}2 connected with the [HAs2 IIIAsVMo8V4 IVO40]4– cluster, resulting in 1D+1D extended into 3D frameworks in 2. Compound 3 contains two types of 1D chains based on [As2 IIIAsVMo8V4 IVO40]5– cluster and copper-tib complexes. The feature of 4 is that the [HAs2 IIIAsVMo8V4 IVO40]4– cluster as a hexa-node is surrounded by {Cu2(bih)}2 units by terminal and bridging oxygen atoms (Ot and Ob) forming 3D POMOFs with Schläfli symbol of {4.64.8}2{42.613}­{44.64.82}2. Additionally, the photocatalytic properties of 1–4 exhibit excellent degradation activity for methylene blue (MB) under UV light, which were ascribed to main active component in generating ·O2 –. The photocatalytic reaction kinetics and mechanism of 1–4 were investigated in detail. Furthermore, luminescence properties of 1–4 were also studied.

Highly Stable Polyoxovanadate-Based Zn–MOF with Dual Active Sites as a Solvent-free Catalyst for C–C Bond Formation

“…31 The apparent absorption bands in the 1200−1600 cm −1 region are assigned to CC and CN of ligand bix. 32 The bond valence sum (BVS) 33 calculations of the V-Zn-MOF reveal that the oxidation states of all V atoms and Zn atoms are +5 and +2, respectively (Table S3). In addition, the XPS experiment of the V-Zn-MOF is carried out to further determine the oxidation states of V and Zn atoms.…”

Arsenomolybdates for Photocatalytic Degradation of Organic Dyes

“…Experimental and theoretical studies of arsenomolybdates photocatalysis have revealed that it typically proceeds based on the following mechanism [41,42,48,52]: Irradiated of arsenomolybdates by UV light with energy equal to or greater than the E g value of itself, which induces intramolecular charge-transfer from the HOMO of O to the LUMO of Mo, leading to the formation of photoexcited states, subsequently photogenerated electron-hole pairs were generated. The O 2 captures electron to form • O 2ˉa nd the hole reacts with H 2 OorOH À ions to form • OH.…”

“…Some research data show that the samples were washed and dried after the arsenomolybdates as photocatalysis several cycles, and the infrared or X-ray diffraction test were carried out, the infrared spectra or X-ray diffraction data of arsenomolybdates demonstrate that there are almost unchanged before and after photocatalytic reaction [44][45][46][47][48], which indicate that arsenomolybdates photocatalysis have excellent structural stability.…”

“…The absorption peaks of MB reduced obviously after 120 min in the presence of four Keggin arsenomolybdates, the degradation rates for MB are 92.9%, 95.8%, 96.6%, and 97.7%, respectively[48].Thephotocatalytic decomposition rate of MB is about 96% for [{Cu (btp) 2 } 3 {As 2 Mo 18 O 62 }] after 40 min [26], and the photocatalytic decomposition rates were 96.32% and 95.57% for [Cu(pyr) 2 ] 6 [As 2 Mo 18 O 62 ] and [Ag (pyr) 2 ] 6 [As 2 Mo 18 O 62 ] after irradiation for 45 min [25]. Yu reported that (H 2 bimyb) 3 (As 2 Mo 18 O 62 ) exhibits high-efficient degradation ability for MB under UV light.…”

Three new POM-based coordination polymers with 1,3,5-tris(1-imidazolyl)benzene ligand: syntheses, structures and proton conductivity

“…As far as we know, only a few cases have been reported with the timb ligand utilized for building POMbased framework materials. [30][31][32] Based on the above considerations, 1,3,5-tris(1-imidazolyl) benzene and Na 2 WO (3). The different structures are discussed, of which compound 1 exhibits a rare 3,6-connected pyr topology, compound 2 displays a rare 3D structure accumulated via two different 2D layers in the BBABB mode and a variety of hydrogen bonding interactions link 1D chains into a 3D network in compound 3.…”