Cadmium-based Metal-organic Framework Research Articles

A luminescent cadmium based MOF as selective and sensitive iodide sensor in aqueous medium

A highly luminescent three–dimensional cadmium based metal–organic framework (Cd-MOF), 1, has been employed for the luminescence-based aqueous phase detection of iodide ion. Emission at 290 nm upon excitation at 226 nm was used for the sensing of iodide ions in aqueous medium through very high luminescence quenching. It was also observed that in presence of other common anions such as NO3−, H2PO4−, CH3COO−, Br−, SO42−, B4O72−, Cl−, CO32−, HPO42− and F− in aqueous medium it shows negligible luminescence quenching. The selectivity of iodide sensing has also been performed in the presence of other halide ions (F−, Cl− and Br−) and the quenching efficiency of iodide remains unaffected by the presence of halide ions. The compound 1 shows high sensitivity even in very low concentration regions towards the sensing of iodide with KSV (quenching constant based on linear Stern–Volmer plot) value of 1.8 × 104 M−1 and with detection limit of iodide of 0.63 μM (80 ppb), which is among the best value known for any luminescence based selective iodide sensor reported to date.

Combining Polycarboxylate and Bipyridyl-like Ligands in the Design of Luminescent Zinc and Cadmium Based Metal–Organic Frameworks

Detailed structural characterization and photoluminescence properties of four new metal–organic frameworks (MOFs) based on zinc(II) or cadmium(II) metal ions, di- or tricarboxylic aromatic ligands, and bipyridyl-like elongated ancillary linkers, namely, {[Zn2(μ4-bdc)2(μ-pbptz)]·2DMF·3H2O}n (1), {[Cd(μ3-bdc)(μ-pbptz)]·3DMF}n (2), {[Cd3(μ5-btc)2(μ-pbptz)]·2DMF}n (3), and {[Zn2(μ-dhbdc)2(μ-pbptz)(DMF)4]·2DMF·H2O}n (4) (where bdc = benzene-1,4-dicarboxylato, btc = benzene-1,3,5-tricarboxylato, dhbdc = 2,5-dihydroxobenzene-1,4-dicarboxylato, pbptz = 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine, DMF = N,N-dimethylformamide) are reported. The occurrence of large accessible volumes and structural and topological diversity are a constant for crystal structures of these compounds, which is a result of the connectivity established among the metal-carboxylato building units formed in each case. Three-dimensional (3D) pcu frameworks of compounds 1 and 2 are built from the linkage of dimeric cores (established by the coordinat...

Cobalt- and Cadmium-Based Metal-Organic Frameworks as High-Performance Anodes for Sodium Ion Batteries and Lithium Ion Batteries.

Two multifunctional metal-organic frameworks (MOFs) with the same coordination mode, [Co(L)(H2O)]n·2nH2O [defined as "Co(L) MOF"] and [Cd(L)(H2O)]n·2nH2O [defined as "Cd(L) MOF"] (L = 5-aminoisophthalic acid) have been fabricated via a simple and versatile scalable solvothermal approach at 85 °C for 24 h. The relationship between the structure of the electrode materials (especially the coordination water and different metal ions) and the electrochemical properties of MOFs have been investigated for the first time. And then the possible electrochemical mechanisms of the electrodes have been studied and proposed. In addition, MOFs/RGO hybrid materials were prepared via ball milling, which demonstrated better electrochemical performances than those of individual Co(L) MOF and Cd(L) MOF. For example, when Co(L) MOF/RGO was applied as anode for sodium ion batteries (SIBs), it retained 206 mA h g-1 after 330 cycles at 500 mA g-1 and 1185 mA h g-1 could be obtained after 50 cycles at 100 mA g-1 for lithium-ion batteries (LIBs). The high-discharge capacity, excellent cyclic stability combined with the facile synthesis procedure enable Co(L) MOF- and Cd(L) MOF-based materials to be prospective anode materials for SIBs and LIBs.

Modelling photophysical properties of metal-organic frameworks: a density functional theory based approach.

Design of optical properties within metal-organic frameworks (MOFs) is a subject of ever increasing attention in recent years with theoretical approaches poised to play a key role alongside experiment in both the understanding of fundamental mechanisms and the further development of high performance materials. We have developed and applied a simple and computationally affordable protocol rooted in density functional theory (DFT) and its time dependent counterpart (TD-DFT) to two isostructural MOFs based on a 4,4'-bis((3,5-dimethyl-1H-pyrazol-4-yl)methyl)-biphenyl (H2DMPMB) linker. These systems show a remarkable dependence of photoluminescence properties on the interchange of zinc and cadmium cations as building units. Our investigation was able to successfully rationalize the subtle change in the photoluminescence mechanism experimentally observed responsible for the large (0.88 eV) red shift (from 335 nm to 441 nm) observed when going from the cadmium to the zinc based structure. More generally, this computational protocol seems well adapted for the characterization and rationalization of the absorption and emission behaviour of such complex extended materials.

Cadmium-Based Metal-Organic Framework as a Highly Selective and Sensitive Ratiometric Luminescent Sensor for Mercury(II).

A novel cadmium-based metal-organic framework (MOF) material with dual-emission signals has been constructed that can act as the first example of MOF-implicated ratiometric sensor for mercury(II) in pure water with a fast response, high selectivity, and sensitivity. The sensing mechanism is also discussed.

Solvent-induced generation of two cadmium-based metal–organic frameworks from 1, 3, 5-benzenetricarboxylic acid ligand

Two cadmium-based metal–organic frameworks (MOFs), namely [Cd5(BTC)4(DMAc)2(H2O)2DMF]·2[H2N(CH3)2]·4DMAc (JUC-133) and [Cd3(BTC)2(DMSO)4] (JUC-134) (JUC=Jilin University, China), based on 1, 3, 5-benzenetricarboxylic acid ligand (H3BTC) were synthesized by solvent-induced strategy under solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, luminescent spectroscopy, TGA analysis, and powder X-ray diffraction. The ligand is connected to cadmium metals to form different cores with distinctive coordination modes to generate different structures. JUC-133 displays a new three-dimensional (3D) topology with the point symbol (4·62)4(4·82)4(42·65·83)4(86) based on Cd2(COO)5 and Cd2(COO)4 as secondary building units (SBUs), which is unknown in previously reported MOFs. JUC-134 can be symbolized as a rutile (rtl) topology with the point symbol (4·62)2(42·610·83) based on Cd3(COO)6 as SBUs. Furthermore, the luminescent of the ligand H3BTC and compounds were measured at room temperature. It is worth noting that the solvent could play an important role in the structural assembly process.

Two cationic metal–organic frameworks based on cadmium and α,ω-alkanedisulfonate anions and their photoluminescent properties

We have successfully synthesized three cadmium-based metal-organic frameworks by utilizing two separate organic linkers to direct the structure. The first material is a three-dimensional neutral framework based on 2D cadmium ethanedisulfonate layers pillared by a 4,4'-bipyridine linker. The other two materials are 3D cationic frameworks and are the first with propanedisulfonate and butanedisulfonate as extraframework charge balancing anions. Both structures occupy a high symmetry hexagonal crystal system where Cd-bipy chains are arranged into three crystallographically distinct layers that stack spirally along [001]. The framework is stabilized by alkanesulfonate anions that are electrostatically and hydrogen bonded to the framework. Each material was characterized by single-crystal and powder X-ray diffraction. The thermal and luminescent properties were also investigated by thermogravimetric analysis and photoluminescence spectroscopy, respectively. All three materials exhibit high thermal stability to above 300 °C and efficient blue emissive photoluminescence centered at 425 nm to 450 nm upon 350 nm excitation.