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Antisense medications treat diseases that cannot be treated using traditional pharmacological technologies. Nucleotide monomers of bare and phosphorothioate (PS)-modified LNA, N-MeO-amino-BNA, 2',4'-BNA NC [NH], 2',4'-BNA NC [NMe], and N-Me-aminooxy-BNA antisense modifications were considered for a detailed DFT-based quantum chemical study to estimate their molecular-level structural and electronic properties. Oligomer hybrid duplex stability is described by performing an elaborate MD simulation study by incorporating the PS-LNA and PS-BNA antisense modifications onto 14-mer ASO/RNA hybrid gapmer type duplexes targeting protein PTEN mRNA nucleic acid sequence (5'- CTTAGCACTGGCCT -3'/3'-GAAUCGUGACCGGA-5'). Replica sets of MD simulations were performed accounting to two data sets, each set simulated for 1 μs simulation time. Bulk properties of oligomers are regulated by the chemical properties of their monomers. As such, the primary goal of this work focused on establishing an organized connection between the monomeric BNA nucleotide's electronic effects observed in DFT studies and the macroscopic behavior of the BNA antisense oligomers, as observed in MD simulations. The results from this study predicted that spatial orientation of MO-isosurfaces of the BNA nucleotides are concentrated in the nucleobase region. These BNA nucleotides may become less accessible for various electronic interactions when coupled as ASOs forming duplexes with target RNAs and when the ASO/RNA duplexes further bind with the RNase H. Understanding such electronic interactions is crucial to design superior antisense modifications with specific electronic properties. Also, for the particular nucleic acid sequence solvation of the duplexes although were higher compared to the natural oligonucleotides, their binding energies being relatively lower may lead to decreased antisense activity compared to existing analogs such as the LNAs and MOEs. Fine tuning these BNAs to obtain superior binding affinity is thus a necessity.

To give a comprehensive account of the environmental acceptability of 1,1,2,3-tetrafluoropropene (CF 2 CF-CH 2 F) in the troposphere, we have examined the oxidation reaction pathways and kinetics of CF 2 CF-CH 2 F initiated by Cl-atoms using the second-order Møller-Plesset perturbation (MP2) theory along with the 6-31+G(d,p) basis set. We also performed single-point energy calculations to further refine the energies at the CCSD(T) level along with the basis sets 6-31+G(d,p) and 6-311++G(d,p). The estimation of the relative energies and thermodynamic parameters of the CF 2 CF-CH 2 F + Cl reaction clearly shows that Cl-atom addition reaction pathways are more dominant compared to H-abstraction reaction pathways. The value of the rate coefficient for each reaction channel is calculated using the conventional transition state theory (TST) over the temperature range of 200-1000 K at 1 atm. The estimated overall rate coefficients for the title reaction are found to be 1.10 × 10 -12 , 1.21 × 10 -10 , and 1.13 × 10 -8 cm 3 per molecule per s via the respective calculation methods viz. MP2/6-31+G(d,p), CCSD(T)//MP2/6-31+G(d,p), and CCSD(T)/6-311++G(d,p)//MP2/6-31+G(d,p), at 298.15 K. Moreover, the calculated rate coefficients and percentage branching ratio values suggest that the Cl-atom addition reaction at the β-carbon atom is more preferable to that of the α-carbon addition to CF 2 CF-CH 2 F. Based on the rate coefficient values calculated by the three different methods, the atmospheric lifetime for the title reaction at 298.15 K is estimated. The radiative efficiency (RE) and Global Warming Potential (GWP) results of the title molecule show that its GWP would be negligible. Further, we have explored the degradation of its product radicals in the presence of O 2 and NO. From the degradation results, we have found that CF 2 (Cl)COF, FCOCH 2 F, FCFO and FCOCl are formed as stable end products along with various radicals such as ˙CF 2 Cl and ˙CH 2 F. Therefore, these findings of kinetic and mechanistic data can be applied to the development and implementation of a novel CFC replacement.

A straightforward and convenient approach for producing AgCN at room temperature using acetonitrile as a source has been developed, employing various iron salts. To date, there have been no prior studies documenting the synthesis of AgCN by cleaving the C-CN bond in acetonitrile with the use of iron salts. The resulting highly crystalline material was subjected to characterization through XRD and FT-IR analysis. Additionally, the same process was used for C-CN bond breaking using Ag 2 S or via the formation of an AgS x O y composite. Consequently, this report is primarily dedicated to exploring the efficacy of different iron salts in breaking the C-CN bond in CH 3 CN. A theoretical investigation of the proposed experimental scheme has also been performed to confer the feasibility of the reaction., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

With the rapid growth of industrialization, deforestation, and burning of fossil fuels, undeniably there has been an incredible escalation of the CO 2 concentration in the atmosphere. In order to mitigate the problem, the capture and utilization of CO 2 in different value-added chemicals have thus remained topics of concerned research for more than a decade. Accordingly, we have performed molecular -level catalytic hydrogenation of CO 2 to formic acid using bare [Cu 2 ] 0,±1 dimers as catalysts. The entire investigation has been performed using a density functional theory (DFT) method employing the Perdew-Burke-Ernzerhof (PBE) functional with the def2TZVPP basis set to explore the different possible routes and efficiency of the catalysts. Results reveal the feasibility of H 2 dissociation on all three Cu 2 , Cu 2 + , and Cu 2 - dimers. The negatively charged hydride formed during H 2 dissociation on Cu 2 and Cu 2 + dimers facilitates the formation of the HCOO* intermediate over COOH*, thereby providing product selectivity for HCOOH above CO. However, the reaction on the Cu 2 - dimer forms both HCOO* and COOH* intermediates, but HCOO*, being kinetically more favorable, results in HCOOH production. The free-energy change suggests that the complete reaction on Cu 2 and Cu 2 + dimers forms a stable product compared to the Cu 2 - dimer. Furthermore, H 3 COH production is studied using the title catalysts via the obtained HCOOH* intermediate from the reaction channel. Transition state theory (TST) has been considered to evaluate the rate constants for each step of the reaction. Overall results suggest Cu 2 to be better compared to Cu 2 + and Cu 2 - dimers for HCOOH formation and Cu 2 + over Cu 2 and Cu 2 - dimers to be more efficient for H 3 COH formation. This work opens the way for further investigation of the reaction mechanism and development of an efficient catalyst for CO 2 hydrogenation.

The cobalt oxide-vanadium oxide (Co 3 O 4 -V 2 O 5 ) combined with reduced graphene oxide (rGO) having band gap of ∼ 3.3 eV appeared as a suitable photocatalyst for selective oxidation of 2-naphthol to BINOL. C2-symmetric BINOL was achieved with good yield using hydrogen peroxide as the oxidant under UV-light irradiation. The same catalyst was chirally modified with cinchonidine and a newly synthesized chiral Schiff base ligand having a sigma-hole center. The strong interaction of the chiral modifiers with the cobalt-vanadium oxide was truly evident from various spectroscopic studies and DFT calculations. The chirally modified mixed metal oxide transformed the oxidative CC coupling reaction with high enantioselectivity. High enantiomeric excess upto 92 % of R-BINOL was obtained in acetonitrile solvent and hydrogen peroxide as the oxidant. A significant achievement was the formation of S-BINOL in the case of the cinchonidine modified catalyst and R-BINOL with the Schiff base ligand anchored chiral catalyst. The UV-light induced catalytic reaction was found to involve hydroxyl radical as the active reactive species. The spin trapping ESR and fluorescence experiment provided relevant evidence for the formation of such species through photodecomposition of hydrogen peroxide on the catalyst surface. The chiral induction to the resultant product was found to induce through supramolecular interaction like OH…π, H…Br interaction. The presence of sigma hole center was believed to play significant role in naphtholate ion recognition during the catalytic cycle., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The present work describes the first visible light-assisted, metal-free and organic base 1,1,3,3-tetramethyl guanidine (TMG) mediated synthesis of unsymmetrical methyl aryl/alkyl carbonates from the reaction of alcohols, methanol, and CO 2 in high to excellent yields under atmospheric pressure and ambient temperature conditions.

Studies on primary gas-phase reactions of emitted saturated and unsaturated ethers with oxidants and subsequent secondary reactions of product radicals with O 2 in the presence of NO are important in their atmospheric chemical processes. To accomplish these findings, we have examined the chemistry of OH-initiated oxidation of isopropenyl methyl ether (i-PME) CH 3 C(CH 2 )OCH 3 by electronic structure ca using density functional theory. Our energetic calculations show that OH additions to carbon-carbon double bonds of i-PME are more favorable reaction pathways than H-abstraction reactions from the various CH sites of the titled molecule. The rate constant values which are obtained from the transition state theory also signify that OH-addition reactions have faster reaction rates than H-abstraction reactions. Our calculated total rate constant of the reaction is found 9.90 × 10 -11 cm 3 molecule -1 s -1 . The percentage branching ratio calculations imply that OH-addition reactions have 98.09% contribution in the total rate constant. The atmospheric lifetime of i-PME is found to be 2.8 h. Further, we have identified 2-hydroxy-2-methoxypropanol, methyl acetate, methy-1,2-hydroxyacetate and 1-hydroxypropane-2-one, 1,2-dihydroxypropan-2-yl format, 2-hydroxyacetic acid, acetic acid, and formaldehyde from the secondary oxidation of product radicals., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Density functional theory method combined with docking and molecular dynamics simulations are used to understand the interaction of carmustine with human glutathione reductase enzyme. The active site of the enzyme is evaluated by docking simulation is used for molecular dynamics simulation to deliver the carmustine molecule by (5,5) single walled carbon nanotube (SWCNT). Our model of carmustine in the active site of GR gives a negative binding energy that is further refined by QM/MM study in gas phase and solvent phase to confirm the stability of the drug molecule inside the active site. Once released from SWCNT, carmustine forms multiple polar and non-polar hydrogen bonding interactions with Tyr180, Phe209, Lys318, Ala319, Leu320, Leu321, Ile350, Thr352 and Val354 in the range of 2-4 Å. The SWCNT vehicle itself is held fix at its place due to multiple pi-pi stacking, pi-amide, pi-sigma interactions with the neighboring residues. These interactions in the range of 3-5 Å are crucial in holding the nanotube outside the drug binding region, hence, making an effective delivery. This study can be extended to envisage the potential applications of computational studies in the modification of known drugs to find newer targets and designing new and improved controlled drug delivery systems.

A density functional theory study has been performed to investigate cation-doped Sn2O4 clusters for selective catalytic reduction of CO2. We study the influence of Si and Ti dopants on the height of the H2 dissociation barrier for the doped systems, and then the subsequent mechanism for the conversion of CO2 into formic acid (FA) via a hydride pinning pathway. The lowest barrier height for H2 dissociation is observed across the 'Ti-O' bond of the Ti-doped Sn2O4 cluster, with a negatively charged hydride (Ti-H) formed during the heterolytic H2 dissociation, bringing selectivity towards the desired FA product. The formation of a formate intermediate is identified as the rate-determining step (RDS) for the whole pathway, but the barrier height is substantially reduced for the Ti-doped system when compared to the same steps on the undoped Sn2O4 cluster. The free energy of formate formation in the RDS is calculated to be negative, which reveals that the hydride transfer would occur spontaneously. Overall, our results show that the small-sized Ti-doped Sn2O4 clusters exhibit better catalytic activity than undoped clusters in the important process of reducing CO2 to FA when proceeding via the hydride pinning pathway.

To understand the atmospheric chemistry of hydrofluoroethers, we have studied the oxidation of a highly fluorinated compound n-C 2 F 5 CF(OCH 3 )CF(CF 3 ) 2 (HFE-7300) by OH/Cl oxidants. Here, we have employed M06-2X functional along with a 6-31 + G(d,p) basis set to obtain the optimized structures, various forms of energies, and different modes of frequencies for all species. We have characterized energies of all species on the potential energy surface, and it indicates that H-abstraction from n-C 2 F 5 CF(OCH 3 )CF(CF 3 ) 2 by Cl atom is kinetically more dominant than the H-abstraction reaction initiated by OH radical. In contrast, the calculated energy change (Δ r H° 298 and Δ r G° 298 ) results govern that OH-initiated H-abstraction reaction is highly exothermic and spontaneous compared to the Cl-initiated H-abstraction reaction. Rate constants are estimated using transition state theory as well as canonical variation transition state theory at the temperature range 200-1000 K and 1 atm pressure. The calculated rate constants of the H-abstraction channels are found to be in good agreement with the reported experimental rate constant at 298 K. Moreover, we have estimated the atmospheric lifetimes of HFE-7300 for the reaction with OH radical and Cl atom and are found to be 1.75 and 153.93 years, respectively. Additionally, the global warming potentials for HFE-7300 molecule are also estimated for 20-, 100-, and 500-year time horizons. Further, subsequent aerial oxidation of product radical (n-C 2 F 5 CF(OCH 2 )CF(CF 3 ) 2 ) in the presence of NO radical is performed, and it produced alkoxy radical via formation of peroxy radical. This alkoxy radical undergoes unimolecular decompositions via two different ways and formed n-C 2 F 5 CF(OCHO)CF(CF 3 ) 2 and n-C 2 F 5 CF(OH) CF(CF 3 ) 2 products.

Degradation of hydrofluoro-olefins (HFOs) with oxidants plays a significant role in the troposphere. Thus, we have investigated detail theoretical calculations of hydroxyl radical ( • OH) initiated oxidation of 2-fluoropropene (CH 3 CFCH 2 ) using M06-2X/6-311++G(d,p) level of theory. Here, we have considered different possible H-abstraction and OH addition for the degradation of CH 3 CFCH 2 molecule. The potential energy analysis shows that OH-addition channels are more dominant than H-abstraction channels. The calculated reaction enthalpies (Δ r H°) and Gibbs free energies (Δ r G°) also suggest that OH-addition reaction channels are more favourable than H-abstraction channels. The overall rate coefficients for CH 3 CFCH 2  +  • OH reaction is calculated within the temperature range of 250-450 K. The observed overall rate coefficient (2.01 × 10 -11  cm 3 molecule -1 s -1 ) at 298 K for the titled reaction is found to be in good agreement with the earlier reported experimental rate coefficient. The calculated percentage branching ratio shows that the contribution of OH-addition to α-carbon and β-carbon of CH 3 CFCH 2 molecule are 85.10% and 14.20% to the overall rate coefficient while H-abstractions have a negligible contribution. Based on the kinetics calculations, the atmospheric lifetime of the titled molecule is found to be 0.6 days. Further, we have also explored the degradation pathways of OH-addition product radicals and found acetyl fluoride (CH 3 CFO) and formaldehyde (HCHO) are the end degradation products., (Copyright © 2019. Published by Elsevier Ltd.)

The OH-initiated oxidation reactions of chloromethyl ethyl ether (CH2ClOCH2CH3) have been presented by using quantum calculation methods. The Minnesota functional (M06-2X) of the density functional theory method along with a polarization and diffuse 6-311++G(d,p) basis set is chosen for optimization and frequency calculations for H-abstractions from CH2ClOCH2CH3 molecules by OH radicals. Furthermore, the CCSD(T) method along with the same basis set is used for energy refinement of all optimized structures to obtain more accurate energies of the species. Our thermo-chemical calculation results show that the C˙HClOCH2CH3 product radical is more stable, corresponding to hydrogen atom abstraction from the -CH2Cl site, than others while the energy profile results indicate that the H-atom abstracted from the -OCH2 site follows the minimum energy path compared to other channels. The rate constants are computed using canonical transition state theory (CTST) within the temperature range of 250-450 K at 1 atm. The overall rate constant (at 298 K) for the abstraction reactions is found to be consistent with the earlier reported rate constant. The percentage branching ratios of different abstraction channels and the lifetime of chloromethyl ethyl ether are also given herein. We further investigated the unimolecular decomposition pathways of the CH2ClOCH(O˙)CH3 radical and found that unimolecular C-C bond scission is the kinetically and thermodynamically more feasible pathway compared to other unimolecular decomposition reactions.

The oxidation of bis(2-chloroethyl) ether (ClCH 2 CH 2 OCH 2 CH 2 Cl) in the atmosphere, as initiated by various oxidants (OH and NO 3 radicals and Cl atoms), was examined using the functional M06-2X in conjunction with the basis set 6-31 + G(d,p). We explored the oxidation pathways and reaction energies (enthalpies and Gibb's free energies) for the abstraction of H from the -CH 2 Cl and -OCH 2 sites of ClCH 2 CH 2 OCH 2 CH 2 Cl by oxidants. The energy profile shows that H abstraction from the -OCH 2 site of the title molecule by each atmospheric oxidant is more likely than H abstraction from the other site. The resulting radical ClCH 2 C • HOCH 2 CH 2 Cl was found to more stable than any other product, as shown by their reaction energies. The rate constants of the oxidation reactions were also calculated using canonical transition state theory in the temperature range 298-400 K. The calculated total rate constant at 298 K is consistent with the reported experimental rate constant. The branching ratio percentages and global atmospheric lifetime of the title molecule are also reported herein.

Oxidation of ethyl vinyl ketone (CH2CHCOCH2CH3) by an OH radical was carried out using the M06-2X/6-311++G(d,p) level of theory. For the OH-initiated oxidation of ethyl vinyl ketone (EVK), we have considered six H-atom abstractions and three addition reactions. From the energetic calculation of the species involved therein, the potential energy surface (PES) of all the reaction channels was constructed. From the energy profile, we found that the H-atom abstraction from the methylene group (-CH2-) of CH2CHCOCH2CH3 is energetically more favourable than the other H-abstraction channels. Moreover, we also observed that OH-addition to the α-carbon of the carbon-carbon double bond of the title molecule is energetically and thermodynamically more dominant than β-carbon and carbonyl carbon. The rate coefficients for all the reaction channels were calculated using the canonical transition state theory at the temperature range of 250-450 K and it reveals that among all the reaction channels, OH-addition to α-carbon is kinetically more dominant to the total rate constant. The total rate coefficient for the reaction at 298 K is found to be in good agreement with the reported experimental rate constant. Finally, we have determined the atmospheric lifetime of the title molecule.

In the present investigation, the oxidation of HFO-1234yf (2,3,3,3-tetrafluoropropene) with O 3 molecule and NO 3 radical is studied by quantum chemical methods. The possible reaction pathways of the titled molecule with O 3 molecule and NO 3 radical are analyzed using M06-2X meta-hybrid density functional with the 6-311++G(d,p) basis set. We have further employed a series of single-point energy calculations by using a potentially high-level couple cluster method with single and double excitations, including perturbative corrections ((CCSD(T)) at the same basis set. The addition reaction of HFO-1234yf with O 3 molecule is initiated by the formation of primary ozonide complex, which leads to the formation of various carbonyl compounds and Criegee intermediates. The calculated energy barriers and thermochemical parameters inferred that decomposition of C˙H 2 OO˙ and CF 3 CFO is slightly more preferred over the formation of CF 3 C˙FOO˙ and CH 2 O. Further, the NO 3 radical addition at α- and β-sits of CF 3 CF〓CH 2 molecule is analyzed in details. The individual and overall rate constants for each reaction pathways are calculated by using canonical transition state theory over the temperature range of 250-450 K. We have observed that the computed rate constants are in good agreement with the available experimental data. Atmospheric lifetimes and global warming potentials of the HFO-1234yf are also reported in this manuscript.

Kinetics and mechanistic pathways for atmospheric oxidation of HFE-7500 ( n-C 3 F 7 CF(OCH 2 CH 3 )CF(CF 3 ) 2 ) initiated by Cl atom and NO 3 radical have been studied using density functional theory. Oxidative degradation pathways facilitated by H-abstraction from the -OCH 2 or -CH 3 groups in HFE-7500 have been considered. It has been shown that H-abstraction from the α-site (-OCH 2 ) is favored over other reaction pathways. The rate constants were computed employing transition-state theory and canonical variation transition-state theory incorporating small curvature tunnelling correction, over the temperature range of 250-450 K at atmospheric pressure. Calculated rate constants at 298 K and 1 atm compare well with earlier experiments. Temperature dependence of the rate constants and branching ratios for these pathways contributing to overall reaction are described. It has been shown that the rate constants over the studied temperature range was found to fit well to the modified Arrhenius equation (in cm 3 molecule -1 s -1 ) k Cl = 1.10 × 10 -14   T 0.04 exp(-69.87 ± 1.41/T) and k NO 3 = 7.66 × 10 -26 T 3.30 exp(596.40 ± 1.22/T). Standard enthalpies of formation for the reactant (C 3 F 7 CF(OCH 2 CH 3 )CF(CF 3 ) 2 ) and the products [C 3 F 7 CF(OC • HCH 3 )CF(CF 3 ) 2 and C 3 F 7 CF(OCH 2 C • H 2 )CF(CF 3 ) 2 ] during H-abstraction are derived using the isodesmic approach. Atmospheric implications of the titled molecule are presented.

Present manuscript represents the DFT studies on the oxidation reaction of camphene initiated by OH radical and fate of product radicals using M06-2X functional along with 6-31+G(d,p) basis set. Intrinsic reaction calculation is done for transition states involving OH-addition reactions which proceed via reaction complexes proceeding to the formation of transition states. The rate constant calculated by using canonical transition state theory at 298 K and 1 atm is found to be 5.67 × 10 -11  cm 3  molecule -1  s -1 which is in good agreement with the experimental rate constant. The atmospheric lifetime of the titled molecule has also been reported in our work.

The present work deals with the theoretical investigation on the Cl initiated H-atom abstraction reaction of sevoflurane, (CF3)2CHOCH2F. A dual-level procedure has been adopted for studying the kinetics of the reaction. Geometrical optimization and frequency calculation were performed at DFT(BHandHLYP)/6-311G(d,p) while single-point energy calculation was made at CCSD(T)/6-311G(d,p) level of theory. The intrinsic reaction coordinate (IRC) calculation has also been performed to confirm the smooth transition from the reactant to product through the respective transition state. The rate constants were calculated using conventional transition state theory (TST). It has been found that 99 % of the reaction proceeded via the H-atom abstraction from the –CH2F end of the sevoflurane. The rate constant of the dominant path is found to be 1.13 × 10⁻¹³ cm³ molecule⁻¹ s⁻¹. This is in excellent agreement with the reported experimental rate constant of 1.10 × 10⁻¹³ cm³ molecule⁻¹ s⁻¹ obtained by relative rate method using FTIR/Smog chamber and LP/LIF techniques.