@article {48067, title = {Coordination flexibility aided CO2-specific gating in an iron isonicotinate MOF}, journal = {Chemistry-an Asian Journal}, volume = {17}, year = {2022}, month = {FEB}, pages = {e202101305}, type = {Article}, abstract = {

Coordination flexibility assisted porosity has been introduced into an Iron-isonicotinate metal-organic framework (MOF), (Fe(4-PyC)(2) . (OH). The framework showed CO2-specific gate opening behavior, which gets tuned as a function of temperature and pressure. The MOF {\textquoteleft} s physisorptive porosity towards CO2, CH4, and N-2 was investigated; it adsorbed only CO2 via a gate opening phenomenon. The isonicotinate, representing a borderline soft base, is bound to the hard Fe3+ centre through monodentate carboxylate and pyridyl nitrogen. This moderately weak binding enables isonicotinate to spin like a spindle under the CO2 pressure opening the gate for a sharp increase in CO2 uptake at 333 mmHg (At 298 K, the CO2 uptake increases from 0.70 to 1.57 mmol/g). We investigated the MOF {\textquoteleft} s potential for CO2/N-2 and CO2/CH4 gas separation aided by this gating. IAST model reveals that the CO2/N-2 selectivity jumps from 325 to 3131 when the gate opens, while the CO2/CH4 selectivity increases three times. Interestingly, this Fe-isonicotinate MOF did not follow the trend set by our earlier reported Hard-Soft Gate Control (established for isostructural M2+-isonicotinate MOFs (M=Mg, Mn)). However, we account for this discrepancy using the different oxidation state of metals confirmed by X-ray photoelectron spectroscopy and magnetism.

}, keywords = {CO2 capture, flexible MOF, gating, Isonicotinic}, issn = {1861-4728}, doi = {10.1002/asia.202101305}, author = {Singh, Himan Dev and Nandi, Shyamapada and Chakraborty, Debanjan and Singh, Kirandeep and Vinod, Chathakudath P. and Vaidhyanathan, Ramanathan} } @article {48070, title = {Covalent organic framework with electrodeposited copper nanoparticles - a desirable catalyst for the Ullmann coupling reaction}, journal = {Journal of Materials Chemistry A}, volume = {10}, year = {2022}, month = {JUL}, pages = {15647-15656}, type = {Article}, abstract = {

A covalent organic framework is a porous covalently-linked polymeric assembly built from molecular lego blocks, the monomers. A COF{\textquoteright}s high surface area, ordered pores, and intrinsic low density makes it a perfect heterogeneous catalyst component. Dispersing catalytic metal nanoparticles into the porous COF matrix in a {\textquoteleft}capping-agent-free{\textquoteright} manner can aid the maximal utilization of the active sites. To generate single-site catalysts, metals have been anchored to dense supports, or metal ions have been coordinated to the porous organic framework. The latter has superior atom efficiency and a substrate diffusion advantage. Stably nestling neutral metallic clusters into open-framework supports with no specifically strong binding groups requires a different approach. If infused from extremely dilute electrolytes, metal clusters can be nanoconfined into electrically activated COFs. At low-loadings, it can resemble a single-site catalyst with high atom efficiency. Herein, we report the larger scale synthesis of IISERP-COF15 and electrochemical loading of copper nanoparticles into its pores at loadings as low as 3.34 wt\%. We employed classical Ullmann reactions to adjudge its activity. Typical turnover numbers for the catalysts reported in the literature are approximately 50-100. A Cu@COF shows high activity with a very low catalyst loading of 0.25 mol\% (TON around similar to 300-350 vs. 4 for neat CuCl2 center dot 2H(2)O (homogeneous catalyst) and turnover frequency (similar to 15-17 h(-1))). We recycled it for up to 3 cycles. Furthermore, we report a multi-fold Ullmann reaction producing an unreported hexaaldehyde to demonstrate the latitude of the catalyst. Our work points to the potential of a dilutely loaded metal@COF as a mimic of the single-site catalyst for synthesizing valuable C-O linked molecules. Our findings from computational modeling shed light on the role of the COF as an active nanoporous support for Ullmann C-O coupling.

}, issn = {2050-7488}, doi = {10.1039/d2ta01326f}, author = {Chandran, Chandana and Singh, Himan Dev and Leo, Liya S. and Shekhar, Pragalbh and Rase, Deepak and Chakraborty, Debanjan and Vinod, Chathakudath P. and Vaidhyanathan, Ramanathan} } @article {48795, title = {COF-supported zirconium oxyhydroxide as a versatile heterogeneous catalyst for Knoevenagel condensation and nerve agent hydrolysis}, journal = {iScience}, volume = {26}, year = {2023}, month = {NOV}, pages = {108088}, type = {Article}, abstract = {

A composite of catalytic Lewis acidic zirconium oxyhydroxides (8 wt \%) and a covalent organic framework (COF) was synthesized. X-ray diffraction and infrared (IR) spectroscopy reveal that COF{\textquoteright}s structure is pre-served after loading with zirconium oxyhydroxides. Electron microscopy confirms a homogeneous distri-bution of nano-to sub-micron-sized zirconium clusters in the COF. 3D X-ray tomography captures the micron-sized channels connecting the well-dispersed zirconium clusters on the COF. The crystalline ZrOx(OH)(y)@COF{\textquoteright}s nanostructure was model-optimized via simulated annealing methods. Using 0.8 mol \% of the catalyst yielded a turnover number of 100-120 and a turnover frequency of 160-360 h(-1) for Knoevenagel condensation in aqueous medium. Additionally, 2.2 mol \% of catalyst catalyzes the hy-drolysis of dimethyl nitrophenyl phosphate, a simulant of nerve agent Soman, with a conversion rate of 37\% in 180 min. The hydrolytic detoxification of the live agent Soman is also achieved. Our study unveils COF-stabilized ZrOx(OH)(y) as a new class of zirconium-based Lewis + Bronsted-acid catalysts.

}, doi = {10.1016/j.isci.2023.108088}, author = {Shekhar, Pragalbh and Devulapalli, Venkata Swaroopa Datta and Reji, Reshma and Singh, Himan Dev and Jose, Aleena and Singh, Piyush and Torris, Arun and Vinod, Chatakudath P. and Tokarz III, John A. and Mahle, John J. and Peterson, Gregory W. and Borguet, Eric and Vaidhyanathan, Ramanathan} }