Function‐Oriented: The Construction of Lanthanide MOF Luminescent Sensors Containing Dual‐Function Urea Hydrogen‐Bond Sites for Efficient Detection of Picric Acid

Abstract

Two novel lanthanide metal–organic framework (Ln‐MOF) luminescent sensors for the detection of picric acid have been successfully assembled. Following a function‐oriented strategy, urea hydrogen‐bonding functional sites were introduced into two MOF frameworks. A structural analysis indicated that the two MOFs have the exact same structure, namely 2D layers with diamond‐shaped holes that are accumulated into a 3D framework through the hydrogen‐bonding interactions between urea and carboxylate groups. Interestingly, only half of the urea units are involved in supporting the MOF framework through N−H⋅⋅⋅O hydrogen‐bonding interactions, whereas the other half are located in the pore channel and act as empty recognition sites. Abundant N−H urea bonds are present in the inner walls of three types of interpenetrating 1D channels. Luminescence studies revealed that the two Ln‐MOFs exhibit high sensitivity, good selectivity, and a fast luminescence quenching response towards picric acid. In particular, the two Ln‐MOFs can be simply and quickly regenerated, and exhibit excellent recyclability. In summary, we have successfully used a function‐oriented strategy to achieve multiple functions in a ligand to construct lanthanide MOF luminescent sensors for the detection of picric acid, thereby providing a potential strategy for the future development of MOF luminescent sensors with a specific target.

Noncovalent Interactions at Lanthanide Complexes

“…The combination of hydrogen bond donor or acceptor sites with a RAHB synthon into metal‐organic frameworks (MOFs) can have an additional advantage on their application in adsorption/separation, [109] catalysis, [110] molecular recognition, [111] etc. For example, the role of hydrogen bonding in lanthanide MOFs for the luminescence response, [112] picric acid detection and fluorescent dyes encapsulation, [113] etc.…”

Mechanistic Insight into Charge and Energy Transfers of Luminescent Metal–Organic Frameworks Based Sensors for Toxic Chemicals

“…The “turn‐off” mechanism and N@H···O hydrogen‐bonding were observed in the detection of picric acid using two novel lanthanide MOFs. [ 171 ] The presence of triazole–CH 2 –anthracene functionalities in the sensor caused quenching of the luminescence spectra, with a “turn‐off” response in the detection of 2,4,6‐trinitrophenol molecules owing to electron transfer from the conduction band (CB) of the sensor to the valence band (VB) of 2,4,6‐trinitrophenol. [ 172 ] Functional groups present in the MOF sensors determine the possible sensing mechanisms.…”

Novel mixed ligand coordination compounds of some rare earth metal cations containing acesulfamato/N,N-diethylnicotinamide

“…Today, in biological applications, clinical studies, NLO (nonlinear optics) applications, OLED (organic light-emitting diode) applications, MOF (metal-organic framework) compounds [17][18][19] and even corrosion inhibitors with traditional and toxic chromate-based compounds demonstrated potential for use [20]. On the other hand, the increasing use of rare earth metal compounds in clinical treatments and medicines may raise some negative concerns about their long-and short-term effects in humans and animals.…”

“…Due to their characteristic photophysical and magnetic properties, their use in magnetic and optical devices [1-6], sensor systems [7], biological analysis applications [8-10], and medical diagnostic devices [11][12][13][14] is increasing.Rare earth metal cations prefer to form metal complexes with high coordination numbers with hard Lewis-based donors such as F, O, and N due to their strong Lewis acid character and large ionic radii. The carboxylic acids containing strong Lewis donor atoms, such as O and N, and polyaminopolycarboxylic acids are among the most suitable coordination ligands for rare earth metal cations with 3+ oxidation steps and meet the high coordination numbers needed [15,16].Today, in biological applications, clinical studies, NLO (nonlinear optics) applications, OLED (organic light-emitting diode) applications, MOF (metal-organic framework) compounds [17][18][19] and even corrosion inhibitors with traditional and toxic chromate-based compounds demonstrated potential for use [20]. On the other hand, the increasing use of rare earth metal compounds in clinical treatments and medicines may raise some negative concerns about their long-and short-term effects in humans and animals.…”