Assembly of Zn-metal organic frameworks based on a N-rich ligand: selective sorption for CO₂ and luminescence sensing of nitro explosives

Abstract

Two novel Zn(II) coordination polymer compounds, namely, [Zn 3 (HL) 2 (fma) 2 ]$DMA$H 2 O (1) and [Zn 2 (m 3 -OH)(HL)(Br-bdc)]$0.5DMA$CH 3 OH$H 2 O (2) have been successfully obtained with 1-(5-tetrazolyl)-4-(1-imidazolyl) benzene ligand and dicarboxylic acids (fma ¼ fumaric acid; Br-bdc ¼ 2-bromoterephthalic acid). Compound 1 exhibits a 3D framework with a square aperture diameter for the channel is 8.8 Â 8.8Å 2 , and the framework can be simplified as a (3,4)-connected tfj network with the point symbol of {4.8 2 } 4 {4 2 .8 4 } 2 {8 4 .12 2 } topology. In compound 2, the HL ligand forms a 2D sheet of Zn(HL) by linking Zn ions along the c axis, which are further connected by double Br-bdc pillars resulting in unique bi-pillared-layer type 3D frameworks. The result, 1a, exhibits a certain degree of CO 2 uptake and selective CO 2 /N 2 adsorption capacity. Furthermore, luminescent properties of 1a well dispersed in different solvents have also been investigated systematically, which demonstrate distinct solventdependent luminescent spectra with emission intensities significantly quenched toward acetone and nitrobenzene.

Two Novel Lanthanide Metal–Organic Frameworks: Selective Luminescent Sensing for Nitrobenzene, Cu2+, and MnO4–

“…The probable causes for luminescence quenching by NB are discussed as follows: (1) The PXRD patterns of 2 in different solvents remained unchanged indicating the collapse of the framework is not the cause of fluorescence quenching (Figure S6); (2) the UV/vis spectra, NB has no absorption band (Figure S7), demonstrating the competing absorption is not the reason; (3) fluorescence intensity of Ln-MOFs largely depend on the energy transfer efficiency between the π conjugated ligand and the Ln 3+ center. Thus, a possible mechanism may be allied to the photoinduced electron transfer (PET) from an electron-rich excited MOF to the electron-deficient NB. − …”

Metal‐Organic Frameworks for Carbon Dioxide Capture and Methane Storage

“…In addition to the accessible N donors, the narrow but suitable channel was demonstrated to be the predominant factors for the remarkable CO 2 /N 2 selectivity. Some other MOFs with uncoordinated N atoms, such as Cd‐4TP‐1, [Zn 2 (CN 5 H 2 ) 3 (H 2 O) 3 ]·6H 2 O, and Zn 3 (HL) 2 (fma) 2 , also exhibit selective CO 2 over N 2 adsorption capacity. However, they have only moderate CO 2 uptakes (1–2.5 mmol g ‐1 ) at 1 bar and 298 K, due to the small surface areas (100–500 m 2 g ‐1 ).…”

A Polyhedral Metal–Organic Framework Based on Supramolecular Building Blocks: Catalysis and Luminescent Sensing of Solvent Molecules

“…Therefore, the photoinduced electron-transfer mechanism appears to provide a good explanation for the quenching effect. The nitrobenzene with the electron-deficient group can obtain an electron from an excited ligand, which has been demonstrated by molecular orbital theory . Therefore, the excited state electrons can transfer from the framework of Eu-PDC (as an electron donor) to nitrobenzene (as an electron acceptor).…”