Investigation of Porous Ni-Based Metal–Organic Frameworks Containing Paddle-Wheel Type Inorganic Building Units via High-Throughput Methods

Abstract

In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4'',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2, 3a, 3b, and 3c. All compounds were structurally characterized. In addition to IR, elemental and TG analyses, gas and vapor sorption experiments were carried out.

SCOPE OF VARIOUS SOLVENTS AND THEIR EFFECTS ON SOLVOTHERMAL SYNTHESIS OF Ni-BTC

“…Interestingly, all of the XRD patterns show different diffraction patterns meaning they are formed with different crystal structures. The XRD patterns from the products in this synthesis are quite different from those reported in various studies, [31][32][33][34] since each and every process has been accomplished with variety of solvents, reaction conditions, metal precursors and reaction modes. Thus every aspect of chemical reaction, whether it is the nature of solvent and precursor, base solution, reaction temperature, synthesis route and reactant concentration, has a strong bearing on the final structure of the product.…”

“…[23][24][25][26][27][28][29] A huge variety of MOFs have been synthesized and reported so far with synthesis techniques such as hydrothermal, solvothermal, microwave assisted heating, mechanochemical, electrochemical and, more recently, ultrasonic processes. 30 Ni-BTC, as a part of this long chain of MOFs, has been initially reported by Yaghi. 31 constructed by btb linkers (btb = benzene 1,3,5-tribenzoate) and {Ni 5 (µ 3 -O) 2 (O 2 C) 6 }, porous paddle-wheel structures using different combination of metal/organic linker/base/solvents via high throughput synthesis 33 and CPO-27(Ni) 34 are few other noticeable contributions to Ni based porous solids.…”

New Group 13 MIL‐53 Derivates based on 2,5‐Thiophenedicarboxylic Acid

“…This whole set-up was placed in a microwave reaction system Synthos3000 by Anton Paar ( Figure S1). [12,54,55] In order to scale-up the reactions, glass vials with a maximum volume of 20 mL were used and the reaction was performed in a Biotage Initiator microwave oven.…”

Discovery of New Calcium Etidronates Employing Ultrasound Adapted High-Throughput Methods

“…15,28,29 The synthesis of inorganic−organic hybrid compounds has been explored with high-throughput methods in solvothermal reactions using conventional electric, and recently microwave assisted dielectric heating has also been employed. 14,27,30 Syntheses applying ultrasound (US) make often use of the high temperatures (5000 K) and high pressures (>1000 atm) that occur in local "hot spots" which are due to cavitation. With fast heating and cooling rates (>10 10 K s −1 ) the energy is rapidly transferred to the reaction mixture.…”