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Showing 1 to 20 of 56 for “"Quantum Chemical Calculations"”.
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Quantum Chemical Calculations of Fermi Contact Coupling Constants In Large Organic Radicals
… designed for conventional electronic structure calculations, serves as a a efficient and reliable method for the calculation of spin densities of large organic radicals when the Rassolov-Chipman operator is utilized, while the method based on delta-function operator may lead to much less …
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Vibrational spectroscopic techniques (Raman, FT-IR and FT-NIR spectroscopy) as a means for the solid-state structural analysis of pharmaceuticals
… certain respiratory disorders and from different chemical and pharmacological entities along with some pharmaceutical excipients. Conventional visual examination is not sufficient to identify and differentiate spectra between different pharmaceuticals. To confirm the assignment of key molecular …
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Noncovalent Interactions Between Alkali Metal Cation And Aza/thia-Crown Macrocycles: Mass Spectrometric Techniques And Theoretical Studies
… with theoretical electronic structure calculations to characterize the structures, binding interactions, and stability of cation-aza-crown ether interactions. Quantum chemical calculations at several levels of theory were employed to characterize the structures and stabilities of the …
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Quantum mechanical study of molecular switches : electronic structure, kinetics and dynamical aspects
… reaction can be induced optically or thermally. Quantum chemical calculations, mostly based on density functional theory, on the AB molecule, AB derivatives and related systems are presented. All the calculations were done for isolated species, however, with implications for latest experimental …
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Coinage Metal Chalcogenide Clusters with N-Heterocyclic Carbene Ancillary Ligands
… transfer energy, for which M = Ag > Cu > Au. Quantum yield of emission is increased in a cluster of high nuclearity and connectivity because of increased molecular rigidity and thermally activated delayed fluorescence. Quantum chemical calculations point to a common mode of emission from all …
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Automatic Generation of Chemical Kinetic Models for Biofuel Oxidation and Pyrolysis
… biofuel combustion and pyrolysis chemistry with chemical kinetic models allows for high-throughput evaluation of their performance under various conditions. These models, typically comprising hundreds of species and thousands of elementary reactions, provide quantitative predictions for the …
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Synthesis, Linear and Nonlinear Photophysical Characterization of Two Symmetrical Pyrene-terminated Squaraine Derivatives in Solution
… and compare them with results obtained through quantum chemical calculations. Both compounds presented high photochemical stability in THF, and the linear spectroscopic characterization revealed high extinction coefficients, large fluorescence quantum yields and relatively low tendency of …
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Aminodiboranates: syntheses, structures, and applications for chemical vapor deposition
… but only one bridges the long Th•••B contact. Quantum chemical calculations suggest that Th(H₃BNMe₂BH₃)₄ is 16-coordinate in the gas phase and that the 15-coordinate solid-state structure can be attributed to packing effects. Compound 1 reacts at elevated temperatures (80–110 °C) to produce …
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Automated Parsing of Flexible Molecular Systems using Principal Component Analysis and K-Means Clustering Techniques
… in each molecular state for meaningful chemical information and subjecting the ensemble to costly quantum chemical calculations. The current status quo typically involves a manual process where the investigator must look at each conformation, separating each into structural families. …
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Accelerating Catalyst Discovery via Ab Initio Machine Learning
… attributed to the fastgrowing development of quantum-chemical methods and learning algorithms. Nevertheless, machine learning for catalysis is still at its initial stage due to our insufficient knowledge of the structure-property relationships. In this regard, we demonstrate a holistic …
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Theoretical studies of the bonding, energetics and spectra of sulfur and phosphorus halides, and reactivity of divalent sulfur compounds: impact of recoupled pair bonding
High-level ab initio, quantum chemical calculations on a number of hypervalent compounds—SFn-1Cl (n=1-6), SCln (n=1-6), PFnCl (n=2-4)—are presented in this dissertation. The bonding in the ground and excited states of these species was analyzed using generalized valence bond theory. These (and …
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Chemical and biochemical applications of vibrational spectroscopy
… into two parts: the first half involves the chemical application of vibrational spectroscopy in determining molecular symmetry and structure, and the second part incorporates these techniques in monitoring protein-substrate binding. To demonstrate some of the chemical applications of …
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Towards the Understanding of Fluorescence Quenching Mechanisms : Molecular Dynamics Simulations of Dye-Quencher Interactions in Biomolecular Systems
… using reference data from high level ab initio quantum chemical calculations. Using this method CHARMM force field parameters for the two dyes were derived. The parameters were then used to perform MD simulations on two simplified, but realistic dye quencher systems: MR121/TRP and R6G/TRP. …
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Multinuclear Solid-State Nuclear Magnetic Resonance Spectroscopy of Microporous Materials
… SSNMR spectroscopy in combination with quantum chemical calculations for computational modeling. Multinuclear SSNMR investigations of two prototypical MOFs with potential industrial applications, CPO-27-M (M = Mg, Zn, Co, Ni), and a-Mg3(HCOO)6, are carried out. The results demonstrate …
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A tale of two small oxygenated molecules as told by photoelectron photoion coincidence spectroscopy
… which is indispensable to derive accurate thermochemical information on large ions. The experimental data on the fragmentation of ions of interest are then examined through modeling the experimental ion fractional abundances (breakdown curves, BDCs) and reaction rates, in a modeling framework …
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Molecular Structure-nonlinear Optical Property Relationships For A Series Of Polymethine And Squaraine Molecules
… to fit the measured 2PA spectra and detailed quantum chemical calculations revealed the reasons for the squaraine to exhibit strong 2PA. In addition, two-photon excitation fluorescence anisotropy spectra were measured through multiple 2PA transitions. A theoretical model based on four-levels …
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Excited state intramolecular proton transfer (ESIPT) to nitrogen in heterocyclic compounds
… temperature and pH conditions. Lifetimes, quantum yields and pKa data were determined under these various conditions and semi-empirical quantum chemical calculations were performed on each system.
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Excited state proton transfer in 2-substituted benzothiazoles
… conditions have been combined with theoretical calculations to arrive at an understanding of the excited state behaviour of HBT and derivatives. An investigation has been made into the protonation and deprotonation of 2-phenylbenzothiazole, 2-(2'-methoxyphenyl)benzothiazole), HBT and derivatives …
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Energetic and kinetic folding mechanisms of the parallel β-helix protein pectate lyase C
… leads to a large increase in the fluorescence quantum yield. This results from the induction of a partially folded protein species upon binding ANS. Thus, ANS does not act as a probe to detect partially folded species, but induces them. The mechanism of ANS binding and structure induction was …
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