School Of Basic And Applied Sciences

Permanent URI for this communityhttps://kr.cup.edu.in/handle/32116/17

Browse

Subject: search.filters.subject.Molecules

Search Results

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Two-dimensional ?-PdX2 (X = S, Te) monolayers for efficient solar energy conversion applications
    (Royal Society of Chemistry, 2022-02-09T00:00:00) Jakhar, Mukesh; Kumar, Ashok
    The search for highly effective and environmentally safe photocatalysts for water splitting and photovoltaic solar cells is essential for renewable solar energy conversion and storage. Based on first-principle calculations, we show that novel 2D ?-PdX2 (X = S, Te) monolayer possesses excellent stability and great potential in solar energy conversion applications. Comprehensive studies show that the ?-PdS2 monolayer exhibits semiconductor characteristics with an indirect gap, suitable band alignment, efficient carrier separation, and high solar to hydrogen (STH) efficiency, supporting its good photoelectronic performance. The surface catalytic and adsorption/intercalation energy calculation reveals that the photogenerated electrons have adequate driving forces to render hydrogen reduction half-reactions to proceed spontaneously and the ability to cover and incorporate water molecules on the ?-PdS2 monolayer. Besides, the ?-PdTe2 monolayer is a promising donor material for excitonic solar cells with high photovoltaic performance. More importantly, due to suitable donor band gap and small conduction band offset in the proposed type-II heterostructure, the power conversion efficiencies (PCE) were calculated up to ?23% (?-PdTe2/WTe2), ?21% (?-PdTe2/MoTe2) and ?18% (?-PdTe2/?-PdS2), making it a promising candidate for solar energy conversion applications. � 2022 The Royal Society of Chemistry
  • No Thumbnail Available
    Item
    Ab Initio Modeling of the ZnO-Cu(111) Interface
    (American Chemical Society, 2021-12-31T00:00:00) Mondal, Krishnakanta; Megha; Banerjee, Arup; Fortunelli, Alessandro; Walter, Michael; Moseler, Michael
    The morphology at the catalytically active interfacial site of ZnO/Cu in the commercial ZnO/Cu/Al2O3 catalyst for CO2 hydrogenation to methanol is still an open question. In the present study, we employ ab initio density functional theory based methods to gain insight into the structure of the ZnO-Cu interface by investigating the morphology of supported ZnO nano-ribbons at the interface with the Cu(111) surface in the presence of hydrogen and water molecules. We find that the stabilities of free-standing ZnO nano-ribbons get enhanced when they are supported on the Cu(111) surface. These supported nano-ribbons are further stabilized by the adsorption of hydrogen atoms on the top of O atoms of the nano-ribbons. Interestingly, the hydrogenated nano-ribbons are found to be equally stable and they appear to be an array of independent chains of ZnOH motifs, suggesting that the hydrogenated nano-ribbons are structurally fluxional. The edge of these fluxional nano-ribbons is stabilized via a triangular reconstruction with a basic composition of Zn6O7H7 in the presence of water molecules. Such a triangular structure gets further stabilized when it is attached to a bulk-like part of the ZnO/Cu(111) system. Furthermore, we find that the triangular reconstruction is energetically favorable even at the methanol synthesis conditions. Therefore, we propose that, under methanol synthesis conditions, the motif Zn6O7H7 represents a stable form at the interface between the bulk-like part of ZnO and the Cu(111) surface in the ZnO/Cu/Al2O3 based commercial catalyst. � 2021 American Chemical Society
  • No Thumbnail Available
    Item
    Adsorption and Activation of CO2on Small-Sized Cu-Zr Bimetallic Clusters
    (American Chemical Society, 2021-03-17T00:00:00) Megha; Mondal, Krishnakanta; Ghanty, Tapan K.; Banerjee, Arup
    Adsorption and activation of CO2 is a key step in any chemical reaction, which aims to convert it to other useful chemicals. Therefore, it is important to understand the factors that drive the activation process and also search for materials that promote the process. We employ the density functional theory to explore the possibility of using small-sized bimetallic Cu-Zr clusters, Cu4-nZrn, with n = 1-3 for the above-mentioned key step. Our results suggest that after adsorption, a CO2 molecule preferably resides on Zr atoms or at the bridge and triangular faces formed by Zr atoms in bimetallic Cu-Zr clusters accompanied with its high degree of activation. Importantly, maximum activation occurs when CO2 is adsorbed on the CuZr3 cluster. Interestingly, we find that the adsorption energy of CO2 can be tuned by varying the extent of the Zr atom in Cu-Zr clusters. We rationalize the high adsorption of CO2 with the increase in the number of Zr atoms using the d-band center model and the concept of chemical hardness. The strong chemisorption and high activation of CO2 are ascribed to charge migration between Cu-Zr clusters and the CO2 molecule. We find an additional band in the infrared vibrational spectra of CO2 chemisorbed on all of the clusters, which is absent in the case of free CO2. We also observe that the energy barriers for the direct dissociation of the CO2 molecule to CO and O decrease significantly on bimetallic Cu-Zr clusters as compared to that on pure Cu4. In particular, the barrier heights are considerably small for Cu3Zr and CuZr3 clusters. This study demonstrates that Cu3Zr and CuZr3 clusters may serve as good candidates for activation and dissociation of the CO2 molecule. � 2021 American Chemical Society.
  • No Thumbnail Available
    Item
    Gaussian field-based 3D-QSAR and molecular simulation studies to design potent pyrimidine-sulfonamide hybrids as selective BRAFV600E inhibitors
    (Royal Society of Chemistry, 2022-10-21T00:00:00) Singh, Ankit Kumar; Novak, Jurica; Kumar, Adarsh; Singh, Harshwardhan; Thareja, Suresh; Pathak, Prateek; Grishina, Maria; Verma, Amita; Yadav, Jagat Pal; Khalilullah, Habibullah; Pathania, Vikas; Nandanwar, Hemraj; Jaremko, Mariusz; Emwas, Abdul-Hamid; Kumar, Pradeep
    The �RAS-RAF-MEK-ERK� pathway is an important signaling pathway in melanoma. BRAFV600E (70-90%) is the most common mutation in this pathway. BRAF inhibitors have four types of conformers: type I (?C-IN/DFG-IN), type II (?C-IN/DFG-OUT), type I1/2 (?C-OUT/DFG-IN), and type I/II (?C-OUT/DFG-OUT). First- and second-generation BRAF inhibitors show resistance to BRAFV600E and are ineffective against malignancies induced by dimer BRAF mutants causing �paradoxical� activation. In the present study, we performed molecular modeling of pyrimidine-sulfonamide hybrids inhibitors using 3D-QSAR, molecular docking, and molecular dynamics simulations. Previous reports reveal the importance of pyrimidine and sulfonamide moieties in the development of BRAFV600E inhibitors. Analysis of 3D-QSAR models provided novel pyrimidine sulfonamide hybrid BRAFV600E inhibitors. The designed compounds share similarities with several structural moieties present in first- and second-generation BRAF inhibitors. A total library of 88 designed compounds was generated and molecular docking studies were performed with them. Four molecules (T109, T183, T160, and T126) were identified as hits and selected for detailed studies. Molecular dynamics simulations were performed at 900 ns and binding was calculated. Based on molecular docking and simulation studies, it was found that the designed compounds have better interactions with the core active site [the nucleotide (ADP or ATP) binding site, DFG motif, and the phospho-acceptor site (activation segment) of BRAFV600E protein than previous inhibitors. Similar to the FDA-approved BRAFV600E inhibitors the developed compounds have [?C-OUT/DFG-IN] conformation. Compounds T126, T160 and T183 interacted with DIF (Leu505), making them potentially useful against BRAFV600E resistance and malignancies induced by dimer BRAF mutants. The synthesis and biological evaluation of the designed molecules is in progress, which may lead to some potent BRAFV600E selective inhibitors. � 2022 The Royal Society of Chemistry.
  • No Thumbnail Available
    Item
    HeH+Collisions with H2: Rotationally Inelastic Cross Sections and Rate Coefficients from Quantum Dynamics at Interstellar Temperatures
    (American Chemical Society, 2022-04-01T00:00:00) Giri, K.; Gonz�lez-S�nchez, L.; Biswas, Rupayan; Yurtsever, E.; Gianturco, F.A.; Sathyamurthy, N.; Lourderaj, U.; Wester, R.
    We report for the first time an accurate ab initio potential energy surface for the HeH+-H2system in four dimensions (4D) treating both diatomic species as rigid rotors. The computed ab initio potential energy point values are fitted using an artificial neural network method and used in quantum close coupling calculations for different initial states of both rotors, in their ground electronic states, over a range of collision energies. The state-to-state cross section results are used to compute the rate coefficients over a range of temperatures relevant to interstellar conditions. By comparing the four dimensional quantum results with those obtained by a reduced-dimensions approach that treats the H2molecule as an averaged, nonrotating target, it is shown that the reduced dimensionality results are in good accord with the four dimensional results as long as the HeH+molecule is not initially rotationally excited. By further comparing the present rate coefficients with those for HeH+-H and for HeH+-He, we demonstrate that H2molecules are the most effective collision partners in inducing rotational excitation in HeH+cation at interstellar temperatures. The rotationally inelastic rates involving o-H2and p-H2excitations are also obtained and they turn out to be, as in previous systems, orders of magnitude smaller than those involving the cation. The results for the H2molecular partner clearly indicate its large energy-transfer efficiency to the HeH+system, thereby confirming its expected importance within the kinetics networks involving HeH+in interstellar environments. � 2022 American Chemical Society. All rights reserved.