A strategy of designed anionic metal–organic framework adsorbent based on reticular chemistry for rapid selective capture of carcinogenic dyes

Exploitation of green synthesized chromium doped zinc oxide nanorods (NRs) mediated by flower extract of Rhododendron arboreum for highly efficient photocatalytic degradation of cationic dyes Malachite green (MG) and Fuchsin basic (FB)

In this work, green method to synthesize chromium-doped zinc oxide (ZnO) nanorods (NRs) using an aqueous flower extract from Rhododendron arboretum is explored. Herein, chromium-doped ZnO NRs were prepared with different amount of chromium doping, varied as 2-10%. The green synthesized products underwent substantial analysis through X-ray diffraction (XRD), spectroscopic such as ultraviolet spectroscopy(UV-Vis) and scanning electron microscopy (SEM) methods. All samples were found to have hexagonal wurtzite ZnO, with average particle sizes of 52.41, 56.6, 54.44, 53.05, and 56.99 nm, respectively, for 2, 4, 6, 8, and 10% chromium doping in ZnO NRs. The Cr-doped ZnO NRs exhibited remarkable photocatalytic degradation activity of cationic dyes under UV-light, i.e., Malachite Green and Fuchsin Basic with degradation of 99.604 and 99.881%, respectively in 90 min. The reusability tests for these green synthesized Cr-doped ZnO NRs have also been carried out, showed 9-11 cycles with 85% of degradation efficiency. In addition, the Cr-doped ZnO NRs exhibited high selectivity for cationic dyes when experiments against mixture of dyes were performed. Photodegradation kinetics followed the pseudo-first-order model. The flower-extract-stabilized chromium-doped ZnO NRs demonstrated high photocatalytic activity toward malachite green and fuchsin basic dyes, potential material for pollution remediation.

Two Solvent-Induced In(III)-Based Metal-Organic Frameworks with Controllable Topology Performing High-Efficiency Separation of C2H2/CH4 and CO2/CH4

For pure acetylene manufacturing and natural gas purification, the development of porous materials displaying highly selective C₂H₂/CH₄ and CO₂/CH₄ separation is greatly important but remains a major challenge. In this work, a plausible strategy involving solvent-induced effects and using the flexibility of the ligand conformation to make two In(III) metal-organic frameworks (MOFs) is developed, showing topological diversity and different stability. The X-shaped tetracarboxylic ligand H₄TPTA ([1,1':3',1″-terphenyl]-4,4',4″,6'-tetracarboxylic acid) was selected to construct two new heteroid In MOFs, namely, {[CH₃NH₃][In(TPTA)]·2(NMF)} (MOF 1) and {[In₂(TPTA)(OH)₂]·2(H₂O)·(DMF)} (MOF 2). MOF 1 is a (4, 4)-connected net showing a pts topology with a large channel that is not conducive to fine gas separation. By contrast, with the reduction of SBU from uninucleated In to an {In-OH-In}_n chain, MOF 2 has a (4, 6)-connected net with the fsc topology with an ∼5 Å suitable micropore to confine matching small gas. The permanent porosity of MOF 2 leads to the preferential adsorption of C₂H₂ over CO₂ with superior C₂H₂/CH₄ (332.3) and CO₂/CH₄ (31.2) separation selectivities. Meanwhile, the cycling dynamic breakthrough experiments showed that the high-purity C₂H₂ (>99.8%) capture capacities of MOF 2 were >1.92 mmol g^-1 from a binary C₂H₂/CH₄ mixture, and its separation factor reached 10.