A novel sustainable metal organic framework as the ultimate aqueous phase sensor for natural hazards: detection of nitrobenzene and F at the ppb level and rapid and selective adsorption of methylene blue

• Published in: CrystEngComm Vol. 22; no. 22; pp. 3891 - 399
• Main Authors: Shahid, M, Saleh, Hatem A. M, Qasem, Khalil M. A, Ahmad, Musheer
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 08.06.2020
• Subjects: Adsorption; Aqueous solutions; Aromatic compounds; Copper; Crystal structure; Crystallography; Dyes; Electron transfer; Energy transfer; Fluorescence; Fluorides; Fourier transforms; Infrared analysis; Magnetic properties; Metal-organic frameworks; Methylene blue; Microporosity; Nitrobenzene; Recyclability; Rhodamine; Selective adsorption; Single crystals; Thermogravimetric analysis; Vapor pressure; Water stability; X ray powder diffraction; X-ray diffraction
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/d0ce00356e

Herein, a new cationic Cu( ii )-based porous and water stable metal-organic framework (MOF), [{Cu(bipy) 1.5 (H 2 pdm)}·2NO 3 ·H 2 O] n ( Cu-MOF-1 ), is synthesised via a slow evaporation process using pyridine-2,6-dimethanol (H 2 pdm) and 4,4′-bipyridine (bipy). The MOF is characterized using Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), magnetic analysis and single-crystal X-ray diffraction analysis. The structural unit of Cu-MOF-1 consists of two Cu( ii ) ions bridged by bipy and supported by H 2 pdm. This material exhibits excellent sensing ability for nitrobenzene (NB) and fluoride ions (F − ) in 100% aqueous medium with an ultra-low limit of detection of 0.093 and 1.203 ppb for NB and F − , respectively. The detection of nitro aromatic compounds (NACs) was found to be governed by photo-induced electron transfer (PET) and fluorescence resonance energy transfer (FRET) mechanisms, while vapour pressure played a major role in NB detection, with a high fluorescence quenching of 96.4%. Moreover, the MOF showed high water stability, significant recyclability and microporosity. The MOF was also employed for the adsorption and separation of methylene blue (MB) from a mixture of three dyes (MB, rhodamine-B and methyl orange). At equilibrium, the removal percentage of Cu-MOF-1 for MB was 98.23% and the mechanism of dye adsorption was also explored. Thus, the present MOF was determined to be a sustainable multifunctional material for the aqueous phase sensing of hazardous NB and fluoride ions, as well as an excellent dye adsorbent. A novel metal organic framework (MOF) exhibits good aqueous phase sensing properties towards nitrobenzene and fluoride anions and selective adsorption/separation ability for methylene blue.