Visible-Light-Driven Photocatalysts of Metal–Organic Frameworks Derived from Multi-Carboxylic Acid and Imidazole-Based Spacer

Abstract

Five new metal−organic frameworks [M-(btec) 0.5 (bimb)] n (1) (M = Co (1), Ni (2), Cu (3), Zn (4)) and [Cd(btec) 0.5 (bimb) 0.5 ] n (5), were obtained by reactions of the conjugated 1,2,4,5-benzenetetracarboxylic acid (H 4 btec) and 4,4′-bis(1-imidazolyl)biphenyl (bimb) with corresponding metal salts under hydrothermal conditions, respectively. MOFs 1-5 show different structures and topologies: compounds 1 and 4 are isomorphic, which possess typical PtS 3D nets; compound 2, 3 and 5 exhibit 2D layer structure, NbO 3D network and (4,6)-connected 3D binodal topology, respectively. Notably, compounds 1, 2, and 5 represent the rare example of MOFsbased visible-light-driven photocatalysts and show good stability toward photocatalysis. Furthermore, compound 5 is photocatalytically more active than 1 and 2 because of the relatively narrower band gap calculated from LMCT transitions. In addition, the formation rate of •OH radicals on compound 5/H 2 O interface via photocatalytic reactions is much higher than that of 1 and 2, implying that the formation rate of •OH radicals during photocatalysis is in agreement with photocatalytic activity and the formation rate of •OH radicals is an important factor influencing photocatalytic performance.

Syntheses and Crystal Structures of Three Cu(II) Coordination Polymers Based on 1,3,5-Tris(imidazol-1-yl)benzene and Benzene Carboxylate Ligands

“…Cu2 is four-coordinated, completed by two oxygen atoms from two different L2 3-anions, and two nitrogen atoms from the timb ligands, leaving a distorted squareplanar coordination geometry. Besides, the bond lengths and bond angles around Cu(II) ions all span in the normal range [42][43][44]. L3 4-anions adopt monodentate coordination mode and connect Cu ions to generate a two-dimensional layer structure (Fig.…”

Visible‐Light‐Driven Photocatalysts of Two Copper(II) Coordination Polymers with Rare Sulfonate and Imidazole Co‐Ligand System

“…For CPs 1 and 2 the absorption wavelengths emerged at 323 and 350 nm with one common broad band roughly at 567 nm, respectively, which can be attributed to ligand-to-metal charge transfer. [11] Photocatalytic Activities CPs 1 and 2 exhibit additional clear absorption bands in the visible region observed at 460-730 nm (peaks at 567 nm), which indicate CPs 1 and 2 may undergo photochemical processes and exhibit responses upon visible-light excitation. [11] Further, to obtain the precise values of bandgap (E g ) from UVvisible absorbance spectra.…”

“…[11] Photocatalytic Activities CPs 1 and 2 exhibit additional clear absorption bands in the visible region observed at 460-730 nm (peaks at 567 nm), which indicate CPs 1 and 2 may undergo photochemical processes and exhibit responses upon visible-light excitation. [11] Further, to obtain the precise values of bandgap (E g ) from UVvisible absorbance spectra. The E g of CPs 1 and 2 were confirmed as the intersection point between the energy axis and the line extrapolated from the linear portion of the adsorption edge in a plot of the Kubelka-Munk function.…”

UiO66–NH2 AS A NEW PHOTOCATALYST FOR THE DEGRADATION OF p–XYLENE IN GASEOUS PHASE

“…With outstanding properties including high surface area, high pore volume, and flexibly tunable structure, MOFs were found to have a wide range of applications in gas adsorption [8,9], separation [10,11], chemical sensing devices [12], and catalysis [13]. Recently, MOFs have been discussed on its potential as a new class of photocatalysts such as MOF-5, isoreticular MOFs (IRMOF-1, IRMOF-2, IRMOF-7, IRMOF-8, IRMOF-9), MIL-53 (M = Al, Cr, Fe), UiO66 and UiO67 [14][15][16][17][18]. However, in the photocatalytic processes, all of the above photocatalysts had a limitation that was the assistance of a sacrificial agent, a co-photocatalyst (Ir, Re), or UV-light as the energy source, which made them underdeveloped compared to inorganic oxide materials.…”