scholarly journals APPLICATION OF PIEZOSENSORS BASED ON THE MOLECULARLY IMPRINTED POLYIMIDE FOR DETERMI-NATION OF CAFFEINE IN TEA

2021 ◽  
pp. 173-180
Author(s):  
Nhat Linh Cao ◽  
Ol'ga Vasil'yevna Duvanova ◽  
Aleksandr Nikolayevich Zyablov ◽  
Anh Tien Nguyen
Keyword(s):  
Interaction Energy ◽  
Quantum Chemical ◽  
Dft Method ◽  
Basis Set ◽  
Molar Ratio ◽  
Polyamic Acid ◽  
Basis Set Superposition Error ◽  
Molecularly Imprinted ◽  
Relative Standard ◽  
Chemical Simulation

In this article the molecularly imprinted polymers (MIPs) have been synthesized on the surface of piezosensors. The starting polymer for MIPs production was polyamic acid, which is a copolymer of 1,2,4,5-benzenetetracarboxylic acid and 4,4′-diaminodiphenyl ether. The caffeine served as the template. The quantum-chemical simulation was performed by the Gaussian 09 software using the DFT method at the B3LYP/6-31G(d,p) level with the basis set superposition error (BSSE) at the preliminary stage of the synthesis of the MIP for caffeine. The prepolymerization complexes were calculated to establish intermolecular interactions and obtain the optimum molar ratio between the template and polyamiс acid. It is shown that the constitutional repeating units of polyamic acid interact with the caffeine by forming H-bonds via carboxyl groups. The interaction energy first increases and then decreases with increasing the molar ratio of imprinting. Based on the quantum-chemical calculations, the optimal ratio of the reagents in prepolymerization mixture was set to 1 : 3 with the highest interaction energy (96.7 kJ/mol). Applying thermal imidization of solution of polyamic acid in the presence of a template, the molecularly imprinted polyimide has been synthesized by the non-covalent imprinting method. The ability of the obtained piezosensors to recognize the tempalte in model mixtures was experimentally evaluated. It was found that the range of detectable concentrations of caffeine is 3.1.10-6-10-1 mol/dm3 and the detection limit is 10-6 mol/dm3. Correctness of the caffeine determination in model solutions was verified in the spike/recovery tests. Piezosensors based on MIP were approved for the determination of the caffeine in tea varieties. It is shown that the concentration of caffeine in the aqueous solution increases with increasing brewing time. The relative standard deviation is less than 8%.

About the overestimation of the basis set superposition error on interaction energy calculations for van der Waals systems

1986 ◽  
Vol 84 (9) ◽  
pp. 5077-5080 ◽  
Author(s):  
F. J. Olivares del Valle ◽  
S. Tolosa ◽  
J. J. Esperilla ◽  
E. A. Ojalvo ◽  
A. Requena
Keyword(s):  
Interaction Energy ◽  
Van Der Waals ◽  
Basis Set ◽  
Basis Set Superposition Error ◽  
Energy Calculations

scholarly journals Halogen Interactions in Halogenated Oxindoles: Crystallographic and Computational Investigations of Intermolecular Interactions

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5487
Author(s):  
Rodrigo A. Lemos Silva ◽  
Demetrio A. da Silva Filho ◽  
Megan E. Moberg ◽  
Ted M. Pappenfus ◽  
Daron E. Janzen
Keyword(s):  
Interaction Energy ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
Basis Set ◽  
Interaction Energies ◽  
Functional Theory ◽  
Basis Set Superposition Error ◽  
Reduced Density Gradient ◽  
Moller Plesset ◽  
Reduced Density

X-ray structural determinations and computational studies were used to investigate halogen interactions in two halogenated oxindoles. Comparative analyses of the interaction energy and the interaction properties were carried out for Br···Br, C-H···Br, C-H···O and N-H···O interactions. Employing Møller–Plesset second-order perturbation theory (MP2) and density functional theory (DFT), the basis set superposition error (BSSE) corrected interaction energy (Eint(BSSE)) was determined using a supramolecular approach. The Eint(BSSE) results were compared with interaction energies obtained by Quantum Theory of Atoms in Molecules (QTAIM)-based methods. Reduced Density Gradient (RDG), QTAIM and Natural bond orbital (NBO) calculations provided insight into possible pathways for the intermolecular interactions examined. Comparative analysis employing the electron density at the bond critical points (BCP) and molecular electrostatic potential (MEP) showed that the interaction energies and the relative orientations of the monomers in the dimers may in part be understood in light of charge redistribution in these two compounds.

scholarly journals Study Of Energy And Structure On Intermolecular Interactions In Organic Solvents Using Computational Chemistry Method

2021 ◽  
Vol 4 (2) ◽  
pp. 79
Author(s):  
Nur Aisah Malau ◽  
Asep Wahyu Nugraha
Keyword(s):  
Organic Solvent ◽  
Computational Chemistry ◽  
Interaction Energy ◽  
Dft Method ◽  
Basis Set ◽  
Hybrid Function ◽  
Calculation Results ◽  
The Difference ◽  
Solvent Molecules ◽  
The Relationship

This study aims to determine the amount of energy, the difference in energy, the relationship between the amount of energy and the distance between compounds, and the interactions that occur in organic solvent molecules using computational chemistry methods. In determining the amount of energy and interactions that occur, computational chemistry calculations are used using NWChem software version 6.6 with the DFT method with the B3LYP hybrid function/basis set 6-31G, the calculation results are visualized using Jmol software. The results of calculations with large computations of energy for benzene are -230.62447487 KJ/mol, ethanol -154.01322923 KJ/mol, methanol -114.98816558 KJ/mol, hexane are -235.27001385 KJ/mol. Mixture of benzene and ethanol in a ratio of 1 : 1 -384.63823964 KJ/mol, 1 : 2 538.66009762 KJ/mol , and 2 : 1 - 615.26607558 KJ/mol. A mixture of benzene and methanol in a ratio of 1 : 1 -345.61255299 KJ/mol, 1 : 2 - 460.60826254 KJ/mol, and 2 : 1 -576.24044425 KJ/mol, a mixture of hexane and ethanol in a ratio of 1 : 1 - 389.28477268 KJ/mol, 1 : 2 -543.29869234 KJ/mol and 2 : 1 -624.55723290 KJ/mol. A mixture of hexane and methanol at a ratio of 1 : 1 -350.25984691 KJ/mol, 1 : 2 -465.26041654 KJ/mol and 2 : 1 -585.53373886 KJ/mole. The difference in energy is the most in a mixture of benzene and ethanol in a ratio of 1 : 2 -0.00916429 K /mol, in a mixture of benzene and methanol in a ratio of 1 : 2 - 0.00745651 KJ/mol, a mixture of hexane and ethanol in a ratio of 2 : 1 -0.00397597 KJ/mol, and a mixture of hexane and methanol in a ratio of 1 : 2 - 0.01407153 KJ/mol. and there is no relationship between the magnitude of the interaction energy of the mixture with the distance between the molecules.

A theoretical study on acetylene dimer, acetylene-s-tetrazine and acetylene-benzene associates

1988 ◽  
Vol 53 (11) ◽  
pp. 2495-2502 ◽  
Author(s):  
Helena Petrusová ◽  
Zdeněk Havlas ◽  
Pavel Hobza ◽  
Rudolf Zahradník
Keyword(s):  
Potential Energy ◽  
Interaction Energy ◽  
Theoretical Study ◽  
Van Der Waals ◽  
Basis Set ◽  
Dispersion Energy ◽  
Basis Set Superposition Error ◽  
Van Der Waals Molecules ◽  
Hartree Fock ◽  
Stabilization Energies

Stabilization energies for the title van der Waals molecules were calculated for various mutual orientations of the subsystems. The interaction energy was expressed as a sum of three contributions: the Hartree-Fock interaction energy, the basis set superposition error and the dispersion energy. The potential energy minima represent reasonably good estimates of the structures of the van der Waals molecules.

scholarly journals Quantum chemical simulation of MoO3 dispergation on hydroxylated SiO2 surface

Surface ◽  
2021 ◽  
Vol 13(28) ◽  
pp. 75-83
Author(s):  
D. B. Nasiedkin ◽  
◽  
M. O. Nazarchuk ◽  
A. G. Grebenyuk ◽  
L. F. Sharanda ◽  
...  
Keyword(s):  
Temperature Interval ◽  
Quantum Chemical ◽  
Basis Set ◽  
Structural Fragment ◽  
Thermally Induced ◽  
Sio2 Surface ◽  
Silanol Groups ◽  
Hartree Fock ◽  
Lcao Approximation ◽  
Chemical Simulation

Метою даної роботи є оцінка енергетичної сприятливості утворення різних молібдатних груп (≡Si‑O‑)2Mo(=O)2 та =Si(‑O‑)2Mo(=O)2 під час термічно ініційованого диспергування MoO3 на гідроксильованій поверхні SiO2. Для цього було здійснено квантовохімічне моделювання реакції O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O в температурному інтервалі 300–1100 K із використанням обмеженого методу Хартрі-Фока (наближення ЛКАО) з валентним базисом SBKJC (Stevens-Basch-Krauss-Jasien-Cundari). Кластер O12Si10(OH)16, який являє собою структурний фрагмент кристала β‑кристобаліту, був використаний як модель високогідроксильованої поверхні кремнезему. Ми розглянули дві структури молібдатних груп (≡Si‑O‑)2Mo(=O)2, прикріплених до кремнеземного кластера O12Si10(OH)16 через силанольні групи. Молібдатні групи (Etot ‑584.60147 Hartree), прикріплені до кремнеземного кластера через віддалені силанольні групи, виявляються більш енергетично вигідними, ніж молібдатні групи (Etot ‑584.56565 Hartree), прикріплені до кремнеземного кластера через сусідні силанольні групи. Енергія молібдатних груп =Si(‑O‑)2Mo(=O)2 (Etot ‑584.48399 Hartree), прикріплених до кремнеземного кластера O12Si10(OH)16 через силандіольні групи, менш енергетично вигідні в порівнянні з подібними групами, прикріпленими через силанольні групи, через більше напруження кута між зв’язками. Знайдено, що реакція O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O в температурному інтервалі 300–1100 K, змодельована шляхом квантовохімічних розрахунків, свідчить, що процес диспергування MoO3 на гідроксильованій поверхні SiO2 є енергетично вигідним. Експ The aim of the present work is to evaluate the energetic favourability of the formation of different molybdate species (≡Si‑O‑)2Mo(=O)2 and =Si(‑O‑)2Mo(=O)2 during the thermally induced MoO3 dispergation on hydroxylated SiO2 surface. In order to do this a quantum chemical modelling of the reaction O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O within the temperature interval of 300–1100 K was undertaken using the Restricted Hartree-Fock method (the LCAO approximation) with the SBKJC (Stevens-Basch-Krauss-Jasien-Cundari) valence basis set. The cluster O12Si10(OH)16 which represents a structural fragment of a β‑cristobalite crystal was used in this work as a model of highly hydroxylated silica surface. We considered two structures of molybdate (≡Si‑O‑)2Mo(=O)2 species attached to O12Si10(OH)16 silica cluster via silanol groups. Molybdate species (Etot ‑584.60147 Hartree) attached to silica cluster via distant silanols appeared more energetically favourable than molybdate species (Etot ‑584.56565 Hartree) attached to silica cluster via nearby silanols. The energy of molybdate =Si(‑O‑)2Mo(=O)2 species (Etot ‑584.48399 Hartree) attached to O12Si10(OH)16 silica cluster via silanediol group is less favourable energetically in comparison with those attached via silanol groups because of higher bond angle straining. The reaction O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O in the temperature interval of 300–1100 K which simulates by quantum chemical calculations the dispergation of MoO3 on hydroxylated SiO2 surface was found to be energetically favourable. The experimentally optimised temperature of ca. 800 K required for dispergation of MoO3 on hydroxylated SiO2 surface is determined by MoO3 evaporation and transportation via the gas phase. ериментальна оптимальна температура (близько 800 K), потрібна для диспергування MoO3 на гідроксильованій поверхні SiO2, визначається випаровуванням та перенесенням MoO3 в газовій фазі.

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