Cobalt(II)-Based Metal–Organic Framework as Bifunctional Materials for Ag(I) Detection and Proton Reduction Catalysis for Hydrogen Production

Abstract

A novel cobalt(II)-based metal−organic framework, Co−MB, was prepared by hydrothermal reaction of Co(NO 3 ) 2 •6H 2 O, 3,3′-methylenediphthalic acid (H 4 mda), and 1,4-bis(imidazol-1-ylmethyl)-benzene in sodium hydroxide aqueous solution and structurally characterized. It shows a high stability in water within the pH range from 2.2 to 11.6, which could be used as a highly selective and sensitive luminescent sensor for Ag(I) detection in a luminescent enhancement manner, with LOD about 23 nM. Importantly, such stable Co−MB could also work as proton reduction catalyst for photodriven hydrogen production coupled with visible-light organic dyes as photosensitizer. The influence factors of hydrogen production including pH, TEA (triethylamine) contents, and kinds of organic dyes are studied in detail. Under optimal condition, the TON value was up to 5133 per cycle, and this Co−MB could also be reused at least 3 times.

Turn-On Luminescent Sensor toward Fe3+, Cr3+, and Al3+ Based on a Co(II) Metal–Organic Framework with Open Functional Sites

“…After being immersed in DMA, it shows green fluorescence with an emission peak at 530 nm, which may be attributed to the excited-state intramolecular proton transfer process resulting from the intramolecular hydrogen bond between adjacent −OH and −COOH. − Moreover, the emission spectra of JXUST-2 and BIBT were obtained in DMA solution at RT. Upon excitation at 394 nm, JXUST-2 reveals an emission peak at 530 nm, which could be mainly on account of the intraligand charge transfer (ILCT) because BIBT also exhibits a similar emission (Figure S6).…”

“…50−52 Moreover, the emission spectra of JXUST-2 and BIBT were obtained in DMA solution at RT. Upon excitation at 394 nm, JXUST-2 reveals an emission peak at 530 nm, which could be mainly on account of the intraligand charge transfer (ILCT) 53 because BIBT also exhibits a similar emission (Figure S6).…”

Cationic Metal–Organic Frameworks Based on Linear Zwitterionic Ligands for Cr2O72– and Ammonia Sensing

“…During the past several decades, metal–organic frameworks (MOFs) based on metal nodes and organic linkers have attracted much attention owing to their fascinating and tailorable structures and properties. − MOFs have shown numerous potential applications including gas sorption and separation, − energy storage and conversion, , luminescent sensors, − catalysis, biomedicine, carbon dioxide capture and fixation, − and so on. − As a subclass of MOFs, cationic MOFs featuring positively charged frameworks are capable of some specific applications such as gas adsorption and separation, colorimetric sensing, and pollutant sensing and removal, including inorganic oxo anions and organic anionic dyes. − However, cationic MOFs have been rarely reported, because the design and synthesis of cationic MOFs are still difficult and challenging. Usually, the choice of metal ions, counteranions, organic ligands, and solvents plays an important role in the construction of cationic MOFs .…”

A {Zn5} cluster‐based metal–organic framework: Multifunctional detection of Ag+, Cr2O72−, and 2,4,6‐trinitrophenol (TNP)

“…Subsequently, we studied the quenching mechanism of 1 in the presence of Ag + , Cr 2 O 7 2− , and TNP. It has been reported that [ 41,44,63–65 ] there are four main mechanisms of fluorescence quenching: (a) exchange between the central cations of the frameworks and the targeted cations; (b) collapse of the crystal structure; (c) interactions between target ions and organic ligands in the structure; and (d) overlap between the absorption spectrum of the analytes and the fluorescence emission spectrum of the host frameworks.…”