Concomitant Metal Organic Frameworks of Cobalt(II) and 3-(4-Pyridyl)benzoate: Optimized Synthetic Conditions of Solvatochromic and Thermochromic Systems

Two coordination networks, {[Co-(34pba)(2)]center dot DMF}(n) (1 and 2), where 34pba is 3-(4-pyridy1)benzoate, were prepared by solvothermal methods. 1 is a three-dimensional metal organic framework formed by linking [Co-2(34pba)(8)] clusters in a bcu net. 2 consists of single [Co(34pba)(4)] units in a tetragonal plane net of sql topology. The thermal conditions leading to their selective synthesis were established: 120 degrees C for 1 and 75 degrees C for 2. Their structures were solved and their thermal behavior was investigated. Further experiments established the activation energy for the desorption of the DMF molecules entrapped in their framework: 76(6)-106(16) kJ mol(-1) for 1 and 49(3)-58(3) kJ mol(-1) for 2. For 1, sorption experiments were carried out to demonstrate the ability of the coordination network to absorb different solvents, and the framework solvatochromic response was also ascertained

Cyclometalation of lanthanum(iii) based MOF for catalytic hydrogenation of carbon dioxide to formate

The hydrogenation of carbon dioxide (CO2) to formic acid is of great importance due to its useful properties in the chemical industry. In this work, we have prepared a novel metal-organic framework (MOF), JMS-1, using bipyridyl dicarboxylate linkers, with molecular formula [La2(bpdc)3(DMF)3]n. Network analysis of JMS-1 revealed a new 7-connected topology (zaz). The MOF backbone of the activated phase (JMS-1a) was functionalized by cyclometalation using [RuCl2(p-cymene)]2 to produce Ru(ii)@JMS-1a. Both JMS-1a and Ru(ii)@JMS-1a were able to convert CO2 in the presence of hydrogen to formate. Ru(ii)@JMS-1a displayed outstanding conversion evidenced by a yield of 98% of formate under optimized conditions of total pressure 50 bar (CO2/H2 = 1 : 4, temperature 110 \ub0C, time 24 h, 5 mmol KOH, 8 mL ethanol). This work is significant in providing new strategies of incorporating active catalytic centres in MOFs for efficient and selective conversion of CO2 to formate

Inclusion propensity of new wheel-and-axle complexes based on Ru(II) half-sandwich units

In this contribution we present the rationalization of the solid-state packing of new organometallic materials with flexible dynamic frameworks, able to create pores on demand in order to accommodate small guest mols. Wheel-and-axle (WAA) systems are known to be good candidates to generate inclusion compds.: they are constituted by two bulky groups (wheels) connected by a rigid linear spacer (axle). Among the complexes synthesized, [(p-cymene)Ru(3-amino-4-hydroxybenzoic acid)I2] and {[(P-Cymene)RuCl2]2[4,4'-bis-(diphenylphosphino)biphenylene]} showed an interesting propension to generate solvate forms through solid-vapor processes; the flexibility of their cryst. networks and the robustness of the supramol. synthons involved are here analyzed

Chiral “doped” MOFs: an electrochemical and theoretical integrated study

This work reports on the electrochemical behaviour of Fe and Zn based metal-organic framework (MOF) compounds, which are “doped” with chiral molecules, namely: cysteine and camphor sulfonic acid. Their electrochemical behaviour was thoroughly investigated via “solid-state” electrochemical measurements, exploiting an “ad hoc” tailored experimental set-up: a paste obtained by carefully mixing the MOF with graphite powder is deposited on a glassy carbon (GC) surface. The latter serves as the working electrode (WE) in cyclic voltammetry (CV) measurements. Infrared (IR), X-ray diffraction (XRD) and absorbance (UV-Vis) techniques are exploited for a further characterization of the MOFs’ structural and electronic properties. The experimental results are then compared with DFT based quantum mechanical calculations. The electronic and structural properties of the MOFs synthesized in this study depend mainly on the type of metal center, and to a minor extent on the chemical nature of the dopant

Synthesis and characterisation of neodymium-based MOFs for application in carbon dioxide reduction to syngas [Elektronisk resurs]

Two new neodymium-based metal-organic frameworks, JMS-10 and JMS-11, were synthesised using a 2,2′-bipypridine-5,5′-dicarboxylic acid (bpdc) linker. Both MOFs were solvothermally synthesised in DMF under different conditions. JMS-10 was synthesised at 120 °C while JMS-11 was synthesised at 100 °C in the presence of a modulator. Both the MOFs possessed very similar crystallographic parameters but were found to be structurally diverse. Their structures were built by secondary building units (SBUs) made up of carboxylates binding in sets of four and two to the straight rod, thus forming two types of alternating nodes that are 6- and 4-connected. Both JMS-10 and JMS-11 were functionalized using the ruthenium p-cymene complex. The functionalized MOFs were applied in the photocatalytic reduction of carbon dioxide to syngas where they produced both hydrogen and carbon monoxide (CO : H2) in the ratio of 1 : 2. The amount of CO to H2 produced varied depending on the additives used in the reaction medium, highlighting the importance of water, triethanolamine and acetonitrile in tuning the syngas ratio for different industrial applications

Tuning the topology of a 2D metal-organic framework from 2D to 3D using modulator assisted synthesis

Two new metal-organic frameworks based on 2,2′-bipyridine-4,4′-dicarboxylate and La(iii) ions were prepared under solvothermal conditions. [La(bpda)3/2(dmf)2]\ub7dmf\ub7H2O, MSU-10, was isolated as a 2D network structure. By introducing a modulator, 1,10-phenanthroline, the 3D network [La(bpda)3/2(dmf)(H2O)2]\ub7dmf MSU-11 could be isolated with the unusual rod-MOF topology zbj. Both the 2D and 3D networks are stable upon guest removal and the activated phases of MSU-10 and MSU-11 exhibit some phase change when soaked in solvents for 24 h. Network analysis allowed the identification of MSU-11 as isoreticular with MOF-80 built from different linkers and metal ions

Hydrogenation of Carbon Dioxide to Formate by Noble Metal Catalysts Supported on a Chemically Stable Lanthanum Rod-Metal-Organic Framework

Cyclometalated with platinum-groupmetals, the La-MOF JMS-5with a bipyridyl dicarboxylate linker gave a TON of over 5000 forIr-(III) and over 4000 for Rh-(III) in the catalytic hydrogenation ofcarbon dioxide to formate without any signs of nanoparticles. Fullcharacterization was performed including XPS, TEM, PXRD, and gas sorption.Single crystal diffraction revealed an unusual rod-MOF topology. The conversion of carbon dioxide to formate is of greatimportancefor hydrogen storage as well as being a step to access an array ofolefins. Herein, we have prepared a JMS-5 metal-organic framework(MOF) using a bipyridyl dicarboxylate linker, with the molecular formula[La-2(bpdc)(3/2)(dmf)(2)(OAc)(3)]center dot dmf. The MOF was functionalized by cyclometalation using Pd-(II),Pt-(II), Ru-(II), Rh-(III), and Ir-(III) complexes. All metal catalystssupported on JMS-5 showed activity for CO2 hydrogenationto formate, with Rh-(III)@JMS-5a and Ir-(III)@JMS-5a yielding 4319 and5473 TON, respectively. X-ray photoelectron spectroscopy of the mostactive catalyst Ir-(III)@JMS-5a revealed that the iridium binding energiesshifted to lower values, consistent with formation of Ir-Hactive species during catalysis. The transmission electron microscopyimages of the recovered catalysts of Ir-(III)@JMS-5a and Rh-(III)@JMS-5adid not show any nanoparticles. This suggests that the catalytic activityobserved was due to Ir-(III) and Rh-(III). The high activity displayedby Ir-(III)@JMS-5a and Rh-(III)@JMS-5a compared to using the Ir-(III)and Rh-(III) complexes on their own is attributed to the stabilizationof the Ir-(III) and Rh-(III) on the nitrogen and carbon atom of theMOF backbone

A single site catalyst supported in mesoporous UiO-66 for catalytic conversion of carbon dioxide to formate

Carbon dioxide utilisation strategies are of paramount importance, yielding various products such as methanol and formate. Formate is an excellent hydrogen carrier in fuel cells, making it a highly exploitable chemical on the hydrogen energy storage front. Formate has an energy content that is at least five times greater than that of commercially available lithium-ion batteries. Herein, we have prepared mesoporous metal-organic frameworks (MOFs) (m-UiO-66 and m-UiO-66-NH2), using a Zr-based secondary building unit (SBU) and terephthalate linkers. The MOFs were used to support the half-sandwich (tetrazolylpyridyl)iridium(iii) complex to make single-site catalyst (Ir(iii)@m-UiO-66 and Ir(iii)@m-UiO-66-NH2) for CO2 conversion to formate. Both Ir(iii)@m-UiO-66 and Ir(iii)@m-UiO-66-NH2 exhibited improved activity for CO2 hydrogenation to formate in a heterogeneous system. Ir(iii)@m-UiO-66-NH2 and Ir(iii)@m-UiO-66 had turnover numbers of 3313 and 3076 TON, respectively, under optimized conditions. X-ray photoelectron spectroscopy (XPS) showed possible interaction of the complex with the MOF as evidenced by a downfield shift in the binding energies of the Ir 4f electronic environment. The catalysts showed post-catalysis stability, as confirmed by PXRD, FTIR, and XPS. The Ir 4f binding energies of the materials after catalysis showed an up-field shift confirming the presence of Ir-H species which are the active species for catalysis

A Co-Crystallised Cobalt(II) Cluster of Pyridinedicarboxylic Acid (PDC) as a Luminescent Material for Selective Sensing of Methanol

A luminescent Cobalt(II) co-crystal [Co13(PDC)16(H2O)24.7H2O] 1 (where H2PDC = 2,6-pyridinedicarboxylic acid) have been prepared by oven-heating and slow evaporation of solvent. Single crystal X-ray diffraction (SCXRD) analysis revealed that 1 is a mixture of complexes that crystallizes in the triclinic space group P-1 and the geometry around the Co(II) ions is octahedral. The structure is extensively imbued with hydrogen bonding that helps in stabilizing the complex. Thermogravimetric analysis indicates that 1 is thermally stable up to 364 οC. The luminescence properties of 1 revealed a strong emission centered at 437 nm (λex = 345 nm) assigned to ligand to metal charge transfer (LMCT). The luminescence sensing of 1 towards volatile organicmolecules were also examined. However, 1 displayed a turn off towards methanol compared to othermolecules with high quenching efficiency and low limit of detection (3.5 × 10−4 vol%). The results show excellent selectively and high sensitivity. Powder X-ray diffraction studies revealed that the structural integrity of the complex was maintained after exposure to methanol vapour. Theoretical studies also revealed small binding energy (−413.2 au) and low energy gap (1.19) for 1-CH3OH adduct