Lanthanide-Based Metal–Organic Frameworks Containing “V-Shaped” Tetracarboxylate Ligands: Synthesis, Crystal Structures, “Naked-Eye” Luminescent Detection, and Catalytic Properties

Abstract

Three lanthanide-based metal–organic frameworks, [Tb­(HMDIA)­(H2O)3]·H2O (Tb-MDIA), [Ho­(HMDIA)­(H2O)3]·(H2O)2 (Ho-MDIA), and [Nd­(HMDIA)­(H2O)3]·(H2O)2 (Nd-MDIA) from the same V-shaped ligand 5,5′-methylenediisophthalic acid (H4MDIA), were prepared by mixing Ln3+ and H4MDIA under solvothermal conditions. The crystal structures of the three complexes were determined by single-crystal X-ray diffraction. The different coordination modes of the organic ligands resulted in different framework structures among the three complexes. The luminescent properties of Ln-MDIA in the ultraviolet–visible region were also studied. Interestingly, the bright-green emitter Tb-MDIA showed high selectivity and sensitivity to allow the naked-eye visualization of Fe3+ ions and picric acid (PA) explosive, and both sensing mechanisms were revealed. Finally, Ho-MDIA and Nd-MDIA were shown to work as heterogeneous catalysts for the cyanosilylation reaction of aromatic aldehydes, and the catalysts could be recycled at least three times without any decrease in activity.

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

“…The Tb−O bond distances are in the range of 2.284(13)−2.539(15) Å, which are comparable to those in the reported terbium−oxygen donor compounds in the literature. 19,38 All carboxylic groups in the deprotonated bcbp ligand take a bidentate bridging coordination mode, which is also called the Harris notation [4.1111] coordination mode (Figure S1). 66 The neighboring Tb1 and Tb2 ions are connected through three bidentate bridging carboxylate groups, forming a T-shaped Tb 2 (bcbp) 3 unit (Figure S2a).…”

“…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 .…”

“…However, the fast and quantitative detection of trace Cr 2 O 7 2– and ammonia is still under development in the field of environmental protection. Luminescent detection, which largely depends on sensors, has been proven to be an effective method because of the facile operation, rapid response, and easy detection in comparison with traditional methods. − Therefore, it is of great importance to rationally design and synthesize luminescent sensors which are qualified to detect Cr 2 O 7 2– and ammonia in a highly selective and sensitive way. Luminescent cationic MOFs are excellent candidates to be sensor materials owing to their high color purity and long fluorescence lifetime.…”

Viologen-Based Cationic Metal–Organic Framework for Efficient Cr2O72– Adsorption and Dye Separation

“…As a promising class of porous materials, metal–organic frameworks (MOFs) have caught considerable attention because of their tunability and diversity in structures and properties during the past decades. − High surface areas and tailorable pores of MOF materials endow them with many appealing applications, such as gas storage and separation, − catalysis, − in magnets, − luminescence and sensing, − and so forth. As a subclass of MOFs, cationic metal–organic frameworks (CMOFs), which possess positive networks, are advantageous in several particular applications including but not limited to colorimetric sensing, ion chromatography, water purification, and anionic pollutant removal. − Compared with neutral MOFs, CMOFs are rarely reported due to the formidable complexity and challenge for their syntheses.…”

Sodalite Cd66-Cage-Based Metal–Organic Framework Constructed by Cd9 and Cd5 Metal–Organic Clusters

“…Cage-based metal–organic frameworks (MOFs), also known as metal–organic polyhedral frameworks, which inherit the advantage of MOF materials, have gained significant popularity owing to their well-defined cavities and high stabilities, which endow cage-based MOFs with outstanding performances in the applications of gas storage/separation, heterogeneous catalysis, water purification, chemical sensing, chemical nanoreaction, drug delivery, and so on . By virtue of the relatively mature synthetic strategies, such as face- and edge-directed methods, multiple cage-based MOFs have been constructed by employing the well-defined molecular building blocks with appropriate geometries .…”