Shyamapada Nandi

Pd loaded amphiphilic COF as catalyst for multi-fold Heck reactions, C-C couplings and CO oxidation.

COFs represent a class of polymers with designable crystalline structures capable of interacting with active metal nanoparticles to form excellent heterogeneous catalysts. Many valuable ligands/monomers employed in making coordination/organic polymers are prepared via Heck and C-C couplings. Here, we report an amphiphilic triazine COF and the facile single-step loading of Pd0 nanoparticles into it. An 18–20% nano-Pd loading gives highly active composite working in open air at low concentrations (Conc. Pd(0) <0.05u2009mol%, average TON 1500) catalyzing simultaneous multiple site Heck couplings and C-C couplings using ‘non-boronic acid’ substrates, and exhibits good recyclability with no sign of catalyst leaching. As an oxidation catalyst, it shows 100% conversion of CO to CO2 at 150u2009°C with no loss of activity with time and between cycles. Both vapor sorptions and contact angle measurements confirm the amphiphilic character of the COF. DFT-TB studies showed the presence of Pd-triazine and Pd-Schiff bond interactions as being favorable.

Ultralow Parasitic Energy for Postcombustion CO2 Capture Realized in a Nickel Isonicotinate Metal–Organic Framework with Excellent Moisture Stability

Metal-organic frameworks (MOFs) have attracted significant attention as solid sorbents in gas separation processes for low-energy postcombustion CO2 capture. The parasitic energy (PE) has been put forward as a holistic parameter that measures how energy efficient (and therefore cost-effective) the CO2 capture process will be using the material. In this work, we present a nickel isonicotinate based ultramicroporous MOF, 1 [Ni-(4PyC)2·DMF], that has the lowest PE for postcombustion CO2 capture reported to date. We calculate a PE of 655 kJ/kg CO2, which is lower than that of the best performing material previously reported, Mg-MOF-74. Further, 1 exhibits exceptional hydrolytic stability with the CO2 adsorption isotherm being unchanged following 7 days of steam-treatment (>85% RH) or 6 months of exposure to the atmosphere. The diffusion coefficient of CO2 in 1 is also 2 orders of magnitude higher than in zeolites currently used in industrial scrubbers. Breakthrough experiments show that 1 only loses 7% of its maximum CO2 capacity under humid conditions.

Hypervalent iodine mediated synthesis of C-2 deoxy glycosides and amino acid glycoconjugates.

A simple, efficient, and practical method for the synthesis of C-2 deoxy-2-iodo glycoconjugates in self-assembled structures was found using PhI(OCOR)2. 2-Iodo glycoserinyl esters were intramolecularly converted into 2-iodo serinyl glycosides which upon dehalogenation gave C-2 deoxy amino acid glycoconjugates.

Bulky Isopropyl Group Loaded Tetraaryl Pyrene Based Azo-Linked Covalent Organic Polymer for Nitroaromatics Sensing and CO2 Adsorption

An azo-linked covalent organic polymer, Py-azo-COP, was synthesized by employing a highly blue-fluorescent pyrene derivative that is multiply substituted with bulky isopropyl groups. Py-azo-COP was investigated for its sensing and gas adsorption properties. Py-azo-COP shows selective sensing toward the electron-deficient polynitroaromatic compound picric acid among the many other competing analogs that were investigated. Apart from its chemosensing ability, Py-azo-COP (surface area 700 m2 g–1) exhibits moderate selectivity toward adsorption of CO2 and stores up to 8.5 wt % of CO2 at 1 bar and 18.2 wt % at 15.5 bar at 273 K, although this is limited due to the electron-rich −N=N– linkages being flanked by isopropyl groups. Furthermore, the presence of a large number of isopropyl groups imparts hydrophobicity to Py-azo-COP, as confirmed by the increased adsorption of toluene compared to that of water in the pores of the COP.

Secondary Interactions Arrest the Hemiaminal Intermediate To Invert the Modus Operandi of Schiff Base Reaction: A Route to Benzoxazinones

Discovered by Hugo Schiff, condensation between amine and aldehyde represents one of the most ubiquitous reactions in chemistry. This classical reaction is widely used to manufacture pharmaceuticals and fine chemicals. However, the rapid and reversible formation of Schiff base prohibits formation of alternative products, of which benzoxazinones are an important class. Therefore, manipulating the reactivity of two partners to invert the course of this reaction is an elusive target. Presented here is a synthetic strategy that regulates the sequence of Schiff base reaction via weak secondary interactions. Guided by the computational models, reaction between 2,3,4,5,6-pentafluoro-benzaldehyde with 2-amino-6-methylbenzoic acid revealed quantitative (99%) formation of 5-methyl-2-(perfluorophenyl)-1,2-dihydro-4H-benzo[d][1,3]oxazin-4-one (15). Electron donating and electron withdrawing ortho-substituents on 2-aminobenzoic acid resulted in the production of benzoxazinones 9-36. The mode of action was tracked using low temperature NMR, UV-vis spectroscopy, and isotopic (18O) labeling experiments. These spectroscopic mechanistic investigations revealed that the hemiaminal intermediate is arrested by the hydrogen-bonding motif to yield benzoxazinone. Thus, the mechanistic investigations and DFT calculations categorically rule out the possibility of in situ imine formation followed by ring-closing, but support instead hydrogen-bond assisted ring-closing to prodrugs. This unprecedented reaction represents an interesting and competitive alternative to metal catalyzed and classical methods of preparing benzoxazinone.

Ultra-low parasitic energy for post-combustion CO2 capture realized in a nickel isonicotinate MOF with excellent moisture stability

Metal-organic frameworks (MOFs) have attracted significant attention as solid sorbents in gas separation processes for low-energy postcombustion CO2 capture. The parasitic energy (PE) has been put forward as a holistic parameter that measures how energy efficient (and therefore cost-effective) the CO2 capture process will be using the material. In this work, we present a nickel isonicotinate based ultramicroporous MOF, 1 [Ni-(4PyC)2·DMF], that has the lowest PE for postcombustion CO2 capture reported to date. We calculate a PE of 655 kJ/kg CO2, which is lower than that of the best performing material previously reported, Mg-MOF-74. Further, 1 exhibits exceptional hydrolytic stability with the CO2 adsorption isotherm being unchanged following 7 days of steam-treatment (>85% RH) or 6 months of exposure to the atmosphere. The diffusion coefficient of CO2 in 1 is also 2 orders of magnitude higher than in zeolites currently used in industrial scrubbers. Breakthrough experiments show that 1 only loses 7% of its maximum CO2 capacity under humid conditions.

A Microporous Mixed Metal-Mixed Ligand Metal Organic Framework for Selective CO2 Capture

A microporous mixed-ligand-based metal–organic framework has been synthesized using two different dicarboxylic acid-based ligands (4,4′-biphenyldicarboxylate (BPDC) and imino diacetate (IMDA)) and two different metal ions (Ce3+ and Na+), namely Ce3Na3(BPDC)3(IMDA)3·(DMF)2(H2O)9. The framework built from Ce–Na–carboxylate layers and BPDC pillars consists of 2D slit-shaped pores occupied by extra-framework Na+ ions. The desolvated framework is permanently porous with a BET surface area of ∼771 m2 g−1 and displays moderate CO2 uptake of 2.0 mmol g−1 with a CO2/N2 selectivity (S) of 68 at room temperature and 1 bar. A modest heat of adsorption (23 kJ mol−1) and smooth diffusion kinetics are observed, as reflected in the facile CO2 cycling. Using GCMC methods, the CO2 adsorption isotherm at 298 K was simulated, which matches the experimental isotherm well. The CO2 positions observed from the simulations showed that Na+ ions in the channels serve as favorable adsorption sites for the oxygen atoms in CO2 pointing toward the Na+ ions (OCO⋯Na+ = 3.34–5.87 A), while some CO2 molecules sit flat on the phenyl rings of the BPDC at a CO2⋯centroid distance of 3.6–3.7 A.

Potentials of Ultramicroporous Metal Organic Frameworks in CO2 Clean-up

This article explains the need for energy-efficient large-scale CO2 capture and briefly mentions the requirements for optimal solid sorbents for this application. It illustrates the potential of ultra-microporous metal-organic frameworks (MOFs, pore size: <7.0 Å) for the separation of CO2 from industrially abundant greenhouse gas mixtures. Some high-performing and well-studied MOFs are discussed to communicate the present status of the field. From their structural features, some successful design principles for creating such ultra-microporous MOFs are derived. Towards the close, favorable CO2 diffusion in many of these small pore MOFs is highlighted.

Ultralow Parasitic Energy for Postcombustion CO 2 Capture Realized in a Nickel Isonicotinate Metal–Organic Framework with Excellent Moisture Stability

Metal-organic frameworks (MOFs) have attracted significant attention as solid sorbents in gas separation processes for low-energy postcombustion CO2 capture. The parasitic energy (PE) has been put forward as a holistic parameter that measures how energy efficient (and therefore cost-effective) the CO2 capture process will be using the material. In this work, we present a nickel isonicotinate based ultramicroporous MOF, 1 [Ni-(4PyC)2·DMF], that has the lowest PE for postcombustion CO2 capture reported to date. We calculate a PE of 655 kJ/kg CO2, which is lower than that of the best performing material previously reported, Mg-MOF-74. Further, 1 exhibits exceptional hydrolytic stability with the CO2 adsorption isotherm being unchanged following 7 days of steam-treatment (>85% RH) or 6 months of exposure to the atmosphere. The diffusion coefficient of CO2 in 1 is also 2 orders of magnitude higher than in zeolites currently used in industrial scrubbers. Breakthrough experiments show that 1 only loses 7% of its maximum CO2 capacity under humid conditions.