@article {48490, title = {Can Li atoms anchored on boron- and nitrogen-doped graphene catalyze dinitrogen molecules to ammonia? a DFT study}, journal = {ChemPhysChem}, volume = {24}, year = {2023}, month = {JUN}, type = {Article}, abstract = {

The most successful electrochemical conversion of ammonia from dinitrogen molecule reported to date is through a Li mediated mechanism. In the framework of the above fact and that Li anchored graphene is an experimentally feasible system, the present work is a computational experiment to identify the potential of Li anchored graphene as a catalyst for N-2 to NH3 conversion as a function of (a) minimum number of Li atoms needed for anchoring on graphene sheets and (b) the role of chemical modification of graphene surfaces. The studies bring forth an understanding that Li anchored graphene sheets are potential catalysts for ammonia conversion with preferential adsorption of N-2 through end-on configuration on Li atoms anchored on doped and pristine graphene surfaces. This mode of adsorption being characteristic of Nitrogen Reduction Reaction (NRR) through enzymatic pathway, examination of the same followed by analysis of electronic properties demonstrates that tri-Li atoms (Tri Atom Catalysts, TACs) are more efficient as catalysts for NRR as compared to two Li atoms (Di Atom Catalysts, DACs). Either way, the rate determining step was found to be *NH2 -\>*NH3 step (mixed pathway) with Delta G(max)=1.02 eV and *NH2-*NH3 -\>*NH2 step (enzymatic pathway) with Delta G(max)=1.11 eV for 1B doped TAC and DAC on graphene sheet, respectively. Consequently, this work identifies the viability of Li anchored graphene based 2-D sheets as hetero-atom catalyst for NRR.

}, keywords = {computational chemistry, Graphene Sheet, heterogeneous catalysis, Li Nanoparticles, Nitrogen Reduction Reaction}, issn = {1439-4235}, doi = {10.1002/cphc.202200750}, author = {Verma, Tushar Singh and Samal, Pragnya Paramita and Selvaraj, Kaliaperumal and Krishnamurty, Sailaja} } @article {48678, title = {Catalyst-assisted selective vinylation and methylallylation of a quaternary carbon center using tert-butyl acetate}, journal = {Journal of Organic Chemistry}, volume = {88}, year = {2023}, month = {JUL}, pages = {9686-9703}, type = {Article}, abstract = {

The In-(OTf)(3)-catalyzed \& alpha;-vinylationof varioushydroxy-functionalized quaternary carbon centers using in situ generatedisobutylene from tert-butyl acetate is presentedas a novel synthetic methodology. Moreover, tert-butylacetate is a nonflammable feed stock and is a readily available sourcefor the in situ production of vinyl substituents, as demonstratedby the vinylation reaction with quaternary hydroxy/methoxy compounds.Moreover, an excellent selectivity for methylallylation over vinylationwas obtained with Ni-(OTf)(2) as a catalyst. In the case ofperoxyoxindole, methylallyl-functionalized 1,4-benzoxazin-3-one derivativeswere formed through the sequential rearrangement of peroxyoxindolefollowed by the nucleophilic attack by isobutylene. The detailed mechanismfor this reaction and rationalization for the selectivity are providedusing kinetics and density functional theory studies.

}, issn = {0022-3263}, doi = {10.1021/acs.joc.2c03072}, author = {Mohanta, Nirmala and Samal, Pragnya Paramita and Pandey, Akanksha M. and Mondal, Shankhajit and Krishnamurty, Sailaja and Gnanaprakasam, Boopathy} } @article {50055, title = {CO2, N2 and H2 adsorption in Zn2+-containing zeolites and metal-organic frameworks}, journal = {Physical Chemistry Chemical Physics}, volume = {28}, year = {2026}, month = {FEB}, pages = {5161-5174}, type = {Article}, abstract = {

We employ a chemically accurate (+/- 4 kJ mol-1) embedding approach to calculate enthalpies for CO2, N2, and H2 adsorption in the Zn2+-containing zeolites FAU and CHA, and for CO2 and H2 in the metal-organic frameworks (MOFs) Zn-MOF-74 and CALF-20. Using MP2 as the high-level method and PBE+D4 as the periodic low-level method (MP2:PBE+D4), we obtain CO2 adsorption enthalpies of -46, -34, and -36 kJ mol-1 for Zn-CHA, Zn-MOF-74, and CALF-20, respectively, all within chemical accuracy limits of the experimental values of -42, -30, and -39 kJ mol-1. For CO2 in Zn-FAU, where no experimental data exist, we provide an MP2:PBE+D4 prediction of -49 kJ mol-1. For N2, we predict MP2:PBE+D4 adsorption enthalpies of -41 and -39 kJ mol-1 in Zn-CHA and Zn-FAU, respectively. CO2 adsorption is stronger in the zeolites than in the studied MOFs. Across all systems, CO2 adsorption tends to be stronger than N2 adsorption and both are largely favoured over H2. We observe inconsistent accuracy of PBE+D4 for the two MOFs, despite their similar characteristics, underscoring the need for high-level approaches in predictive screening. Additionally, we conclude that Zn2+ cations with open coordination sites act as the primary binding sites and that these cations preferentially occupy 6-membered rings in zeolites.

}, issn = {1463-9076}, doi = {10.1039/d5cp04169d}, author = {Samal, Pragnya Paramita and Berger, Fabian and Krishnamurty, Sailaja and Sauer, Joachim} }