Nitro aromatics are the principal components of explosives used in acts of terrorism and within improvised explosive devices, among others. Although high sensitivity towards nitro aromatic explosives has been demonstrated, selective detection and discrimination are critical for practical applications. Fluorescence quenching of metal-organic frameworks (MOFs) is sufficiently sensitive to detect any nitro explosives, but discriminative detection with different numbers of -NO 2 groups is rare. Here we report a stable fluorescent MOF, [Zn 2 (NDC) 2 (bpy)]$G x , 1 (where NDC ¼ 2,6-naphthalenedicarboxylic acid, bpy ¼ 4,4 0bipyridine, and G ¼ guest solvent molecules), whose fluorescence is quenched by trace amounts of nitro aromatics introduced from solution or in vapor phase. The steady-state and time-resolved experiments show that the quenching process is dynamic in nature and the interactions (dipole-dipole, p-stacking) between the MOF and nitro explosives play a crucial role in the discriminative detection of nitro aromatics with different numbers of -NO 2 groups.
A complete transmetalation has been achieved on a barium metal-organic framework (MOF), leading to the isolation of a new Tb-MOF in a single-crystal (SC) to single-crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core-shell metal exchange through dissociation of metal-ligand bonds. This Tb-MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF.
Ac omplete transmetalation has been achieved on ab arium metal-organic framework (MOF), leading to the isolation of an ew Tb-MOF in as ingle-crystal (SC) to singlecrystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed ac ore-shell metal exchange through dissociation of metal-ligand bonds.This Tb-MOF exhibits enhanced photoluminescence and acts as as elective sensor for phosphate anion in aqueous medium. Thus,t his work not only provides am ethod to functionalize aMOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF.
A series of metal-organic frameworks based on alkaline earth metal ions (Ca, Sr and Ba) and 1,3,5benzenetribenzoic acid (BTB) have been synthesized and characterized. These are [H 2 NIJCH 3 ) 2 ]ijCa 7 IJBTB) 5 - 3). All the structures are three-dimensional in nature with different secondary building units. Compound 1 contains one-dimensional Ca-O-Ca zigzag chains while compound 2 contains Sr 5 O 28 pentameric clusters and compound 3 contains one-dimensional Ba-O-Ba chains. Both compounds 1 and 3 form (3,6)-net connectivity while compound 2 forms (3,12)-net connectivity. Optical band gap energy measurements show that compound 1 (2.65 eV) has low band gap energy compared to 2 (3.22 eV) and 3 (3.32 eV). This variation in band gap energy may be due to the difference in structural arrangement. Compound 3 crystallizes in a non-centrosymmetric space group (Pna2 1 ), which belongs to the polar point group C 2v . This compound displays a strong SHG response and good ferroelectric and piezoelectric properties.
Smarter and minimization of devices are consistently substantial to shape the energy landscape. Significant amounts of endeavours have come forward as promising steps to surmount this formidable challenge. It is undeniable that material scientists were contemplating smarter material beyond purely inorganic or organic materials. To our delight, metal‐organic frameworks (MOFs), an inorganic‐organic hybrid scaffold with unprecedented tunability and smart functionalities, have recently started their journey as an alternative. In this review, we focus on such propitious potential of MOFs that was untapped over a long time. We cover the synthetic strategies and (or) post‐synthetic modifications towards the formation of conductive MOFs and their underlying concepts of charge transfer with structural aspects. We addressed theoretical calculations with the experimental outcomes and spectroelectrochemistry, which will trigger vigorous impetus about intrinsic electronic behaviour of the conductive frameworks. Finally, we discussed electrocatalysts and energy storage devices stemming from conductive MOFs to meet energy demand in the near future.
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