2632-99-7Relevant articles and documents
A “Thermodynamically Stable” 2D Nickel Metal–Organic Framework over a Wide pH Range with Scalable Preparation for Efficient C2s over C1 Hydrocarbon Separations
Sahoo, Rupam,Chand, Santanu,Mondal, Manas,Pal, Arun,Pal, Shyam Chand,Rana, Malay Kumar,Das, Madhab C.
, p. 12624 - 12631 (2020)
The design and construction of “thermodynamically stable” metal–organic frameworks (MOFs) that can survive in liquid water, boiling water, and acidic/basic solutions over a wide pH range is highly desirable for many practical applications, especially adsorption-based gas separations with obvious scalable preparations. Herein, a new thermodynamically stable Ni MOF, {[Ni(L)(1,4-NDC)(H2O)2]}n (IITKGP-20; L=4,4′-azobispyridine; 1,4-NDC=1,4-naphthalene dicarboxylic acid; IITKGP stands for the Indian Institute of Technology Kharagpur), has been designed that displays moderate porosity with a BET surface area of 218 m2 g?1 and micropores along the [10?1] direction. As an alternative to a cost-intensive, cryogenic, high-pressure distillation process for the separation of hydrocarbons, MOFs have recently shown promise for such separations. Thus, towards an application standpoint, this MOF exhibits a higher uptake of C2 hydrocarbons over that of C1 hydrocarbon under ambient conditions, with one of the highest selectivities based on the ideal adsorbed solution theory (IAST) method. A combination of two strategies (the presence of stronger metal–N coordination of the spacer and the hydrophobicity of the aromatic moiety of the organic ligand) possibly makes the framework highly robust, even stable in boiling water and over a wide range of pH 2–10, and represents the first example of a thermodynamically stable MOF displaying a 2D structural network. Moreover, this material is easily scalable by heating the reaction mixture at reflux overnight. Because such separations are performed in the presence of water vapor and acidic gases, there is a great need to explore thermodynamically stable MOFs that retain not only structural integrity, but also the porosity of the frameworks.
Control over catenation in metal-organic frameworks via rational design of the organic building block
Farha, Omar K.,Malliakas, Christos D.,Kanatzidis, Mercouri G.,Hupp, Joseph T.
, p. 950 - 952 (2010)
(Chemical Equation Presented) Metal-organic frameworks (MOFs), a hybrid class of materials comprising inorganic nodes and organic struts, have potential application in many areas due to their high surface areas and uniform pores and channels. One of the key challenges to be overcome in MOF synthesis is the strong propensity for catenation (growth of multiple independent networks within a given crystal), as catenation reduces cavity sizes and diminishes porosity. Here we demonstrate that rational design of organic building blocks, which act as strut-impervious scaffolds, can be exploited to generate highly desired noncatenated materials in a controlled fashion.
Synthesis and characterization of four novel manganese(II) chains formed by 4,4′-azobis(pyridine) and benzoate or nitrobenzoates: Stabilization of unusual ladder structures
Kar, Paramita,Drew, Michael G.B.,Gómez-García, Carlos J.,Ghosh, Ashutosh
, p. 229 - 239 (2013)
Four new manganese(II) coordination polymers: [Mn(4,4′-azpy)(C 6H5COO)2](4,4′-azpy)0.5 (1), [Mn(4,4′-azpy)(p-(NO2)C6H4COO) 2] (2), [Mn(4,4′-azpy)(m-(NO2)C6H 4COO)2] (3) and [Mn(4,4′-azpy)(o-(NO 2)C6H4COO)2(H2O) 2] (4), where 4,4′-azpy = 4,4′-azobis(pyridine), have been synthesized by self-assembly of MnX2 (X = benzoate, p-, m-, or o-nitrobenzoates) together with 4,4′-azpy. All four complexes were characterized by elemental analyses, IR spectroscopy, thermal analyses, single-crystal X-ray diffraction analyses and variable-temperature magnetic measurements. The structural analyses reveal that complexes 1, 2 and 3 feature a 1D molecular ladder formed by syn-syn (complex 1) or syn-anti (complexes 2 and 3) carboxylate-bridged dimeric Mn(II) units which are joined together by 4,4′-azpy ligands. In complex 1, these ladders assemble with the help of π-π and C-H?π interactions to form a nanoporous framework that incorporates non coordinated 4,4′-azpy molecules by exploiting host-guest C-H?π and hydrogen bonding interactions. Complex 2 presents a 3D supramolecular framework by π-π and CH?π interactions, whereas, complex 3 having a similar ladder structure to 1 and 2, forms a 2D grid through π-π interactions. On the other hand, complex 4 is a 4,4′-azpy bridged fish-bone chain of carboxylate-coordinated mononuclear manganese(II) units, which are linked together by strong hydrogen bonds to form a 2D structure. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of weak antiferromagnetic interactions within the discrete Mn-(OCO)2-Mn dimers for complexes 1, 2 and 3 that have been fitted with a S = 5/2 dimer model (J = -0.8, -0.5 and -0.4 cm-1 respectively). The magnetic data of complex 4 can be reproduced with a S = 5/2 monomer model including a Zero Field Splitting (|D| = 1.7 cm-1).
Two Closely Related Zn(II)-MOFs for Their Large Difference in CO2 Uptake Capacities and Selective CO2 Sorption
Chand, Santanu,Chattaraj, Pratim K.,Das, Madhab C.,Das, Prasenjit,Pal, Arun,Saha, Ranajit,Sahoo, Rupam
, (2020)
Two azo functionalized Zn(II)-based MOFs, {[Zn(SDB)(3,3′-L)0.5]·xG}n, IITKGP-13A, and {[Zn2(SDB)2(4,4′-L)]·xG}n, IITKGP-13B (IITKGP stands for Indian Institute of Technology Kharagpur), have been constructed through the self-assembly of isomeric N,N′-donor spacers (3,3′-L = 3,3′-azobispyridine and 4,4′-L = 4,4′-azobispyridine) with organic ligand 4,4′-sulfonyldibenzoic acid (SDBH2) and Zn(NO3)2·6H2O (G represents disordered solvent molecules). Single-crystal X-ray diffraction studies reveal the 2D structure with sql topology for both MOFs. However, the subtle change in positions of coordinating N atoms of spacers makes IITKGP-13A noninterpenetrated, while IITKGP-13B bears a 2-fold interpenetrated structure. IITKGP-13A exhibits higher uptake of CO2 over CH4 and N2 with high IAST selectivities for mixed CO2/CH4 (50:50, biogas) and CO2/N2 (15:85, flue gas) gas systems. In contrast, IITKGP-13B takes up very low amount of CO2 gas (0.4 mmol g-1) compared to IITKGP-13A (1.65 mmol g-1) at 295 K. Density functional theory (DFT)-based electronic structure calculations have been performed to explain the origin of the large differences in CO2 uptake capacity between the two MOFs at the atomistic level. The results show that the value of the change in enthalpy (ΔH) at 298 K temperature and 1 bar pressure for the CO2 adsorption is more negative in IITKGP-13A as compared to that in IITKGP-13B, thus indicating that CO2 molecules are more favored to get adsorbed in IITKGP-13A than in IITKGP-13B. The computed values for the Gibbs' free energy change (ΔG) for the CO2 adsorption are positive for both of the MOFs, but a higher value is observed for the IITKGP-13B. The noncovalent types of interactions are the main contribution toward the attractive energies between the host MOF frameworks and guest CO2 molecules, which has been studied with the help of energy decomposition analysis (EDA).
4-Pyridylnitrene and 2-pyrazinylcarbene
Wentrup, Curt,Reisinger, Ales,Kvaskoff, David
, p. 754 - 760 (2013)
Both flash vacuum thermolysis (FVT) and matrix photolysis generate 2-diazomethylpyrazine (22) from 1,2,3-triazolo[1,5- a]pyrazine (24). FVT of 4-azidopyridine (18) as well as of 24 or 2-(5-tetrazolyl)pyrazine (23) affords the products expected from the nitrene, i.e., 4,4'-azopyridine and 2- and 3-cyanopyrroles. Matrix photolyses of both 18 and 24 result in ring expansion of 4-pyridylnitrene/2-pyrazinylcarbene to 1,5-diazacyclohepta-1,2,4,6-tetraene (20). Further photolysis causes ring opening to the ketenimine 27.
Bifunctional Cs?Au/Co3O4 (Basic and Redox)-Catalyzed Oxidative Synthesis of Aromatic Azo Compounds from Anilines
Oseghale, Charles O.,Fapojuwo, Dele Peter,Alimi, Oyekunle Azeez,Akinnawo, Christianah Aarinola,Mogudi, Batsile M.,Onisuru, Oluwatayo Racheal,Meijboom, Reinout
supporting information, p. 5063 - 5073 (2021/09/30)
An eco-friendly alkali-promoted (Cs?Au/Co3O4) catalyst, with redox and basic properties for the oxidative dehydrogenative coupling of anilines to symmetrical and unsymmetrical aromatic azo compounds, was developed. We realized a base additive- and molecular O2 oxidant-free process (using air), with reasonable reusability of the catalyst achieved under milder reaction conditions. Notably, the enhanced catalytic activity was also linked to the increased basic site concentration, low reduction temperatures, and the effect of lattice oxygen on the nanomaterials. The increased basic strength of the cation-promoted catalyst improved the electron density of the active Au species, resulting in higher yields of the desired aromatic azo compounds.
Electrochemical dehydrogenation of hydrazines to azo compounds
Du, Ke-Si,Huang, Jing-Mei
supporting information, p. 1680 - 1685 (2019/04/08)
A strategy for the electrochemical dehydrogenation of hydrazine compounds is disclosed under ambient conditions. This protocol proceeded smoothly in ethanol by employing electrons as clean oxidants. Its synthetic value is well demonstrated by the highly efficient synthesis of symmetric and unsymmetric azo compounds. It is an environmentally friendly transformation and the present protocol was effective on a large scale.
Reversing Chemoselectivity: Simultaneous Positive and Negative Catalysis by Chemically Equivalent Rims of a Cucurbit[7]uril Host
Rad, Nazar,Danylyuk, Oksana,Sashuk, Volodymyr
supporting information, p. 11340 - 11343 (2019/07/16)
Enzyme catalysis has always been an inspiration and an unattainable goal for chemists due to features such as high specificity, selectivity, and efficiency. Here, we disclose a feature neither common in enzymes nor ever described for enzyme mimics, but one that could prove crucial for the catalytic performance of the latter, namely the ability to catalyze and inhibit two different reactions at the same time. Remarkably, this can be realized by two identical, spatially resolved catalytic sites. In the future, such a synchronized catalyst action could be used not only for controlling chemoselectivity, as in the present case, but also for regulating other types of chemical reactivity.
Induction of chirality in 4,4′-azopyridine by halogen-bonding interaction with optically active ditopic donors
Alfuth, Jan,Chojnacki, Jaros?aw,Po?oński, Tadeusz,Olszewska, Teresa
, p. 5512 - 5517 (2019/04/04)
Optically active ditopic halogen bond donors bearing two 4-iodotetrafluorophenyl groups were obtained by reaction of chiral diols with iodopentafluorobenzene. Co-crystallization of these donors with anti-4,4′-azopyridine afforded binary complexes containing infinite chains of the alternating component molecules connected by halogen bonds. The solid state CD measurements confirmed that complexation induces optical activity of the azo chromophore due to the twisting of the aryl-N═N system or external chiral perturbation exerted by host molecules.
Thermally Twistable, Photobendable, Elastically Deformable, and Self-Healable Soft Crystals
Gupta, Poonam,Karothu, Durga Prasad,Ahmed, Ejaz,Naumov, Pan?e,Nath, Naba K.
supporting information, p. 8498 - 8502 (2018/07/14)
The first example of a smart crystalline material, the 2:1 cocrystal of probenecid and 4,4′-azopyridine, which responds reversibly to multiple external stimuli (heat, UV light, and mechanical pressure) by twisting, bending, and elastic deformation without fracture is reported. This material is also able to self-heal on heating and cooling, thereby overcoming the main setbacks of molecular crystals for future applications as crystal actuators. The photo- and thermomechanical effects and self-healing capabilities of the material are rooted in reversible trans–cis isomerization of the azopyridine unit and crystal-to-crystal phase transition. Fairly isotropic intermolecular interactions and interlocked crisscrossed molecular packing secure high elasticity of the crystals.
