Search

Five stable tautomer and rotamers of the 2-(2-Mercaptophenyl)-1-azaazulene (thiol, thione, R1, R2, and R3) molecules were studied using density functional theory (DFT). The geometries of the studied tautomer and rotamers were fully optimized at the B3LYP/6-31G(d,p) level. Thermodynamic calculations were performed at M06-2X/6-311G++(2d,2p) and ωB97XD/6-311G++(2d,2p) in the gas phase and ethanol solution conditions modeled by the solvation model based on density (SMD). The kinetic constant of tautomer and rotamers conversion was calculated in the temperature range 270–320 K using variational transition state theory (VTST) accompanied by one-dimensional wigner tunneling correction. Energy refinement at CCSD(T)/6–311++G(2d,2p) in the gas phase has been calculated. All the studied DFT methods qualitatively give similar tautomer stability orders in the gas phase. The ethanol solvent causes some reordering of the relative stability of 2-(2-Mercaptophenyl)-1-azaazulene conformers. The transition states for the 2-(2-Mercaptophenyl)-1-azaazulene tautomerization and rotamerization processes were also determined. The reactivity, electric dipole moment, and spectroscopic properties of the studied tautomer and rotamers were computed. The hyper-Rayleigh scattering (βHRS), and depolarization ratio (DR) exhibited promising optical properties when nonlinear optical properties were calculated. [ABSTRACT FROM AUTHOR]

Five stable tautomer and rotamers of the 2-(2-Mercaptophenyl)-1-azaazulene (thiol, thione, R1, R2, and R3) molecules were studied using density functional theory (DFT). The geometries of the studied tautomer and rotamers were fully optimized at the B3LYP/6-31G(d,p) level. Thermodynamic calculations were performed at M06-2X/6-311G++(2d,2p) and ωB97XD/6-311G++(2d,2p) in the gas phase and ethanol solution conditions modeled by the solvation model based on density (SMD). The kinetic constant of tautomer and rotamers conversion was calculated in the temperature range 270–320 K using variational transition state theory (VTST) accompanied by one-dimensional wigner tunneling correction. Energy refinement at CCSD(T)/6–311++G(2d,2p) in the gas phase has been calculated. All the studied DFT methods qualitatively give similar tautomer stability orders in the gas phase. The ethanol solvent causes some reordering of the relative stability of 2-(2-Mercaptophenyl)-1-azaazulene conformers. The transition states for the 2-(2-Mercaptophenyl)-1-azaazulene tautomerization and rotamerization processes were also determined. The reactivity, electric dipole moment, and spectroscopic properties of the studied tautomer and rotamers were computed. The hyper-Rayleigh scattering (βHRS), and depolarization ratio (DR) exhibited promising optical properties when nonlinear optical properties were calculated. [ABSTRACT FROM AUTHOR]

The intriguing properties of polycyclic structure known as benzenoid hydrocarbons, which are unsaturated and totally conjugated molecules with hexagonal rings, continue to entice researchers to investigate their chemical and physical molecular structure with reference to aromaticity. To correlate important molecular structural attributes such as enthalpy, melting, boiling point, and cyclicity, numerical descriptors or topological indices which have been used for decades, for variety of two and three dimensional chemical structures networks or graphs with vital physicochemical properties. To determine the degree‐based topological indices, in this study, the degrees of the chemical structure or graph of the molecule under examination are utilized. In molecular graph theory, M‐polynomial is a relatively recent approach for investigating chemical networks and structures. It shows numerical descriptors in algebraic form and highlights molecular properties as a polynomial function. In this study, we propose a polynomials presentation of two‐dimensional coronene fractal structures and compute numerous M‐polynomials, including the M‐polynomials of the first and second Zagreb indexes, as well as the Randic index. [ABSTRACT FROM AUTHOR]

Recently, the upper bounds on the static time-reversal (T) and spatial parity (P)-violating electron electric dipole moment (eEDM) and dimensionless constant, characterizing the strength of the T , P -violating scalar–pseudoscalar nucleus–electron interaction, have been updated in the JILA experiment using the HfF+ cations. We considered two other sources of the T , P -violation in HfF+–axion-like-particle (ALP)-mediated scalar–pseudoscalar electron–electron and nucleus–electron interactions. To estimate the magnitude of effects, induced by such interactions in HfF+ we have developed and applied a method which implies the direct use of the ab initio relativistic coupled cluster theory to calculate molecular parameters that characterize the interactions. Using these parameters, we showed that an order of magnitude updated laboratory constraints on the ALP-mediated electron–electron and nucleus–electron interactions can be derived from the experimental data on T , P -violating effects in HfF+ for a wide range of ALP masses. [ABSTRACT FROM AUTHOR]

An Aristotelian philosophy of nature offers an alternative to reduction for the conception of the inter-theoretical relationships between molecular chemistry and quantum mechanics. A basic ingredient for such an approach is an ontology of fundamental causal powers, and this work aims to develop such an ontology by drawing on quantum-chemical entities, particularly, the electron density. This notion is central to the Quantum Theory of Atoms in Molecules, a theory of molecular structure developed by Richard F. W. Bader, which describes molecules and atoms in terms precisely of the electron density. Then, by identifying a philosophical tension in Bader's discourse about the nature of electron density, the work will analyze this central notion in terms of the categorical/dispositional distinction regarding properties. The central idea is that electron density can be conceived as categorical and dispositional at once, and this very characterization can avoid Bader's philosophical tension. [ABSTRACT FROM AUTHOR]

Theoretical frames for analyzing information in biological and molecular multicomponent structures are proposed. The mathematical foundations of the proposal are presented. Both the information encoded in structures is defined and the method of calculating the amount of this information is introduced. The proposed approach is applied to the operation of a molecular multicomponent machine. [ABSTRACT FROM AUTHOR]

Nanoscience has progressed exponentially during the previous few decades, moving from bench science to complex applied technologies. Nanomaterials found their application in large number of industrial products which includes filters, paints, insulation, electronic components, lubricant additives, biomedical applications, etc. One such important nanomaterial is lead sulphide, an inorganic compound with the chemical formula PbS, and is one of the most common ore of Galena. The graphical depiction of the molecular structure determines how the atoms are organised in real three-dimensional space. Graphical representation encloses a detailed study of the physical and chemical properties of molecules for the calculation of degree and distance-based graph parameters. Such parameters are termed as topological indices of graph and are usually numerical parameters. The resolvability parameters of a graph are a highly innovative topic in which the entire structure is molded to obtain each atom's unique position. In this work, we consider some degree and distance-based graph parameters of an inorganic compound, namely, lead sulphide. In particular, we study its metric dimension and fault-tolerant metric dimension. We also obtain first, second, and third Zagreb index for PbS. [ABSTRACT FROM AUTHOR]

We propose a molecular theory for fluids of structured molecules based on the Born-Bogoliubov-Green-Kirkwood-Yvon (BBGKY) hierarchy for classical fluids. We treat the polyatomic molecules as an N-body mixture of its constituent moieties. The reassembly of these chemical units into the original molecules is achieved via the site-site interaction potentials. To find the usual total correlations and direct correlations, we incorporate the Lebowitz-Percus functional derivatives, i.e. the 'fluctuation-compressibility' derivatives into the first member of the BBGKY. This enables us to construct a generalised Ornstein-Zernike equation for the system of dimeric molecules. We are able to separate out from the resulting equation a part that is identified as the direct correlation functions. This equation involves higher order correlations, namely the triplet correlation functions. We contrast this direct correlation with those from the earlier reference interaction site model (RISM) and exhibit the differences between the two approaches. A new theoretical framework is established, as an alternative to other current theories for polyatomic molecular fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] The previously observed effects of nonpolar additives on the scission energy and rheological properties of surfactant wormlike micelles can be explained in terms of the spatial distribution of the additive within the micelles. The dependence of the scission energy with the molecular organization of the system can be analyzed with a molecular theory capable of describing the thermodynamics and structure of the micelles. A new theoretical method to determine the scission energy of surfactant wormlike micelles is introduced. This methodology is based on a molecular theory that explicitly considers molecular details of all components of the micelles, and their inter- and intramolecular interactions without the use of fitting and/or empirical macroscopic parameters. The predicted effects of the concentration, molecular structure and hydrophobicity of the additive on the scission energy of cetyltrimethylammonium bromide (CTAB) wormlike micelles are found to be in qualitative agreement with previous experimental observations. In particular, our theory captures the decrease of micellar length with increasing content of highly hydrophobic additives and the non-monotonic dependence of the viscosity with additive hydrophobicity. The latter effect arises because highly and mildly hydrophobic additives affect the scission energy of wormlike micelles via markedly different molecular mechanisms. [ABSTRACT FROM AUTHOR]

Recently, A. Kovalenko et al. reported the computational study of molecular structure and energetics of CO2 + H2 reduction reaction on Cu-, Cu2O-, Fe-, and Fe3O4-based nanocatalysts in the J. Mol. Model., 26, 267 (2020). The authors claim that they developed and tested the multiscale modeling description of this process by combining the periodical boundary condition density functional theory (PBC DFT) and molecular theory of solvation. However, due to inappropriate selection of intermediate strictures, in particular, the unfavorite structure of CO* adsorbed on Cu-, Cu2O-, Fe-, and Fe3O4-nanoparticles, and some inconsistency in preparation of initial structures by DFT approach, there are serious concerns about the correctness and quality of the presented results. In addition, by this comment, I would like to help other researchers working on the development of new catalysts for electrochemical reduction of CO2 to avoid further misunderstandings following this study. [ABSTRACT FROM AUTHOR]

[Display omitted] • Enhanced thermal conductivity by tuning the polymer intrinsic structure. • Enhancement of polymer thermal conductivity using external conditions. • Analysis of thermal conductivity contribution factors by bonding cooperation. • Modulation of polymer thermal conductivity by cross-linking degree. The inherent thermal transport properties of epoxy resin are vital factors to be studied in applications. In the present work, we constructed the amorphous crosslinking structure, the step crosslinking structure and the ordered crosslinking structure based on molecular dynamics theory, and used the reverse nonequilibrium molecular dynamics (RNEMD) method to calculate the thermal conductivity (TC) of different structures. Based on the numerical verification of the reliability of the method, the contribution of bonding to the TC was enhanced by increasing the molecular arrangement orderliness to reduce phonon scattering, taking the composition of the TC contribution as the guide. Meanwhile, the contribution of non-bonding interaction to the TC was enhanced by using compression process to achieve TC increase in the epoxy resin intrinsic structure, followed by exploring the effect of cross-linking degree on the TC of different structures. The results showed that the TC of amorphous epoxy resin decreased with the increase of crosslinking degree, and the relative high-frequency VDOS increased, but the influence of crosslinking degree on TC was minor in the range. For amorphous epoxy resin four-sided pressurization varied in the range of 0–7 Gpa, the non-bond energy percentage increased in the range of 0–60%, and the increase of non-bond energy made its contribution to TC increased significantly. The epoxy resin achieved 215% improvement in intrinsic TC by changing the molecular arrangement orderliness. The ordered structure TC varied from 0.3 to 3.5 W/(m⋅K) in the pressure variation range of 0–7 GPa. As the structure becomes more ordered, the TC increased significantly with the degree of cross-linking. The study provided the theoretical basis for the realization of resin preparation and resin thermal property evaluation with regulated intrinsic TC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Benzothiazole based Schiff bases showed excellent anticorrosive property in 1 M HCl. • Electrochemical study unveiled corrosion inhibition efficiency of the studied inhibitors. • Heteroatoms and molecular structure effecting corrosion inhibition has been explained. • FESEM, AFM and contact angle confirmed inhibitors' adsorption on mild steel surface. • DFT, Fukui indices, NCI-RDG, MD simulation and RDF analysis validated experimental findings. Synthesis of challenging corrosion inhibitors is of prime importance to inhibit hydrogen-induced and localised metallic corrosion occur in the corrosive acidic solution. In this regard, the present research has been focused on the development of functionalised Schiff bases, namely, 1-(benzo[ d ]thiazol-2-yl)-2-((furan-2-yl)methylene)hydrazine (BTFMH), 1-(benzo[ d ]thiazol-2-yl)-2-((thiophen-2-yl)methylene)hydrazine (BTTMH), 1-(benzo[ d ]thiazol-2-yl)-2-((5-methylthiophen-2-yl)methylene)hydrazine (BTMMH) with an aim of effectively curtailing the issues associated to hydrogen-induced cracking and subsequent inhibition of metallic corrosion taking place in the corrosive acidic solution. The corrosion inhibiting performances of the synthesized inhibitors have been assessed for mild steel surfaces exposed in 1 M HCl medium using gravimetric measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization study revealed that the synthesized inhibitor molecules retarded the cathodic hydrogen evolution reaction at cathodic site and subsequently minimized the oxidation of metals at anode; thereby, these Schiff bases acted as the mixed type inhibitors. The EIS study revealed that the corrosion inhibition phenomenon is being controlled through charge transfer processes. All of these three synthesized inhibitor molecules showed approximately 96–98 % corrosion inhibiting efficiency at exceedingly low concentration (0.5 mM). The inhibition efficacy obtained for these synthesized inhibitor molecules follows the order: BTMMH > BTTMH > BTFMH. The adsorption nature of these inhibitor molecules on mild steel surfaces have been revealed through surface morphology, topography and water contact angle studies. Thereafter, the insight of corrosion inhibition mechanism at atomic level have been explored by density functional theory (DFT). The optimized geometrical structure, electron density distribution of frontier molecular orbitals and their corresponding energy parameters obtained from DFT as well as Fukui indices analysis have been explored to unveil the plausible modes of adsorption or the reactive sites present within the inhibitor molecules which facilitate their interactions with surface atoms of metals. The non-covalent interaction based on reduced density gradient have been explored to study intrinsic feeble interaction acting with the molecules. Afterwards, molecular dynamics simulation has been employed to validate the spontaneity along with the nature of interaction at the metal inhibitor interface. Furthermore, the equilibrium adsorption configuration of the synthesized inhibitor molecules on the targeted metal surface atoms have been envisaged and the interfacial phenomenon has been explained. [ABSTRACT FROM AUTHOR]

Magnetic nanomaterial-based electrochemical cytosensor holds great promise to tackle the challenges in isolation and detection of circulating tumor cells (CTCs) by the combination of the selectivity of magnetic cell separation with high sensitivity of electrochemical sensing platforms. Herein, by leveraging nanomaterials with L -cysteine and folic acid, we design innovative biomaterials for electrochemical cell detection, with minimal materials and materials manufacturing steps. Folic acid- L -cysteine-capped CoFe 2 O 4 nanoparticles (CCF) are developed to magnetically capture folate-overexpressed tumor cells. Hybrids of L -cysteine-folic acid and silver nanowires (FAgNWs) are synthesized using a green, convenient and template-free approach without any surfactant. Direct immobilization of L -cysteine and folic into silver nanowires hybrids facilitates the electrode preparation and cell detection. The density functional theory and molecular dynamics simulations were also used to provide deep insight into the interaction of silver nanowires with L -cysteine coupled with folic acid (LCFA). An affordable nanocytosensor is proposed for the detection of CTCs by sandwiching the MCF-7 cells captured between CCF and FAgNWs. This nanocytosensor has the low detection limit of 5 MCF-7 cells/mL with the wide dynamic range of 50–106 cells/mL. The presented nanomaterial-based sensing platform is promising for convenient cell isolation and detection. [Display omitted] • Magnetic isolation of circulating tumor cells were carried out using functional CoFe 2 O 4 magnetic nanoparticles. • Hybrids of L -cysteine-folic acid and silver-nanowires (FAgNWs) were deveoped for cell sensing. • The presented sandwich-like electrochemical platform successfully detected MCF-7 cells with the low detection limit of 5 cells/mL. • The deep insight into the FAGNWs molecular structures provided by the density functional theory and molecular dynamic simulations. [ABSTRACT FROM AUTHOR]

Liquid-crystalline D-A dyads and A-D-A triads, based on the chemical association of electron-donor (D) triphenylene discogens and electron-acceptor (A) perylene/benzoperylene diimides, have been synthesized by the Pd-catalyzed Sonogashira coupling/DBU-promoted cyclization reactions tandem. These molecular heterojunctions spontaneously self-organize into columnar hexagonal (Col hex) or/and rectangular (Col rec) mesophases, over broad temperature ranges including room temperature, with the antagonist moieties segregated into alternated homo-molecular (homolithic) stacks within mixed columns. Their intramolecular electron and energy transfers have been studied by UV/Vis absorption and fluorescence emission spectroscopies. Due to photo-induced electron transfer between donor and acceptor units, fluorescence quenching is systematically observed for all the dyads and triads. This study further reveals that perylenediimide is a stronger electron acceptor than the larger benzoperylenediimide building block. Density function theory calculations of their molecular structures and HOMO-LUMO energy levels and gaps support the experimental results and demonstrate that these donor-acceptor systems have potential applications in various optoelectronic devices. • Dyad and triad discotic mesogens were synthesized by Sonogashira coupling/DBU-promoted cyclization reactions tandem. • Fluorescence quenching is observed for all compounds due to photo-induced electron transfer between donors and acceptors. • The compounds exhibit hexagonal and rectangular columnar mesophases over broad temperature ranges. [ABSTRACT FROM AUTHOR]