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Journal articles on the topic 'AM1 semiempirical calculation'

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Published: 3 June 2025

Last updated: 31 July 2025

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1

Iswanto, Ponco, Eva Vaulina Yulistia Delsy, Ely Setiawan, and Heny Ekowati. "Selection of semiempirical calculation methods for insecticide development." Acta Pharmaciae Indonesia : Acta Pharm Indo 11, no. 1 (2023): 7046. http://dx.doi.org/10.20884/1.api.2023.11.1.7046.

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Background: Insecticides are substances used to control, repel, or eradicate troublesome organisms, particularly insect-based plant pests. The discovery of new insecticide compounds fuels the ongoing development of insecticides. The integration of computational chemistry into the development of insecticidal chemicals was beneficial. Objective: This study aims to identify the most suitable method among 12 available semiempirical calculation methods in the Hyperchem application. Methods: The selection process involved comparing experimental data of the infra-red spectrum of chlorpyri

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2

Barrett, Rosemary A., and Robert J. Meier. "The calculation of molecular entropy using the semiempirical AM1 method." Journal of Molecular Structure: THEOCHEM 363, no. 2 (1996): 203–9. http://dx.doi.org/10.1016/0166-1280(95)04438-8.

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3

Jorge, N. L., L. C. A. Leiva, M. G. Castellanos, M. E. Gomez Vara, L. F. R. Cafferata, and E. A. Castro. "Experimental and Theoretical Study of the Enthalpy of Formation of 3,6-Diphenyl-1,2,4,5-Tetroxane Molecule." Scientific World JOURNAL 2 (2002): 455–60. http://dx.doi.org/10.1100/tsw.2002.126.

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We report the results obtained for the experimental determination and the theoretical calculation of the enthalpy of formation of 3,6-diphenyl-1,2,4,5-tetroxane molecule. The experimental work was performed using a macrocalorimeter to measure the combustion heat, and the sublimation enthalpy was determined via the measurement of the vapor pressure at equilibrium with the vapor phase at different temperatures resorting to the Clapeyron-Claussius equation. Theoretical calculations were performed using semiempirical AM1 and PM3 methods as well asab initiotechniques at the 3-21, 6-31G(d,p), and 6-

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Istyastono, Enade Perdana, Sudibyo Martono, Harno Dwi Pranowo, and Iqmal Tahir. "QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIP ANALYSIS OF CURCUMIN AND ITS DERIVATIVES AS GST INHIBITORS BASED ON COMPUTATIONAL CHEMISTRY CALCULATION." Indonesian Journal of Chemistry 3, no. 3 (2010): 179–86. http://dx.doi.org/10.22146/ijc.21886.

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The Quantitative Structure-Activity Relationship (QSAR) study was established on curcumin and its derivatives as glutathione S-transferase(s) (GSTs) inhibitors using atomic net charges as the descriptors. The charges were resulted by semiempirical AM1 and PM3 quantum-chemical calculations using computational chemistry approach. The inhibition activity was expressed as the concentration that gave 50% inhibition of GSTs activity (IC50). The selection of the best QSAR equation models was determined by multiple linear regression analysis. This research was related to the nature of GSTs as multifun

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Iswanto, Ponco, Irvan Maulana Firdaus, Ahmad Fawwaz Dafaulhaq, Ahmad Ghifari Ramadhani, Maylani Permata Saputri, and Heny Ekowati. "Quantitative Structure-Activity Relationship of 3-Thiocyanate-1H-Indoles Derived Compounds as Antileukemia by AM1, PM3, and RM1 Methods." Jurnal Kimia Sains dan Aplikasi 26, no. 3 (2023): 109–17. http://dx.doi.org/10.14710/jksa.26.3.109-117.

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Cancer is a disease with fatal consequences; thus, searching for innovative compounds with anticancer properties remains an active pursuit. One of the highly promising candidates is a compound derived from 3-thiocyanato-1H-indoles. However, the number of derivative compounds is currently limited. A quantitative structure and activity relationship (QSAR) study was conducted on derivate compounds 3-thiocyanato-1H-indoles to establish equations that predict the anticancer activity of more effective derivatives. This study aims to compare the effectiveness of the AM1 (Austin Model 1), PM3 (Paramet

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6

Tahir, Iqmal, Karna Wijaya, and Titik Subarni. "MODELING OF ALKYL SALICYLATE COMPOUNDS AS UV ABSORBER BASED ON ELECTRONIC TRANSITION BY USING SEMIEMPIRICAL QUANTUM MECHANICS ZINDO/s CALCULATION." Indonesian Journal of Chemistry 2, no. 1 (2010): 64–72. http://dx.doi.org/10.22146/ijc.21934.

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Modeling of several alkyl salicylates based on electronic transition by using semiempriical mechanical quantum ZINDO/s calculation has been done. Object of these research were assumed only alkyl salicylates of C4 (butyl) until C8 (octyl) homologue with 4-7 example structures of each homologue. All of the computation have been performed using quantum chemistry - package software Hyperchem 6.0. The research covered about drawing each of the structure, geometry optimization using semiempirical AM1 algorithm and followed with single point calculation using semiempirical ZINDO/s technique. ZINDO/s

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7

Böhm, Stanislav, Pavel Šebek, Stanislav Nešpůrek, and Josef Kuthan. "Photocolouration of 2,4,4,6-Tetraaryl-4H-thiopyrans: A Semiempirical Quantum Chemical Study." Collection of Czechoslovak Chemical Communications 59, no. 5 (1994): 1115–25. http://dx.doi.org/10.1135/cccc19941115.

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Molecular geometries of 4H-thiopyrans Ia, Ib and their possible photoisomers IVa - VIIa and IVb - VIIb were optimized by the AM1 and PM3 method and used for the calculation of electronic absorption spectra by the CNDO/S-CI procedure. Comparison of the theoretical data with experimental UV-VIS absorption spectra made it possible to postulate two probable mechanisms of the photocolouration of Ia, Ib caused by sunlight or UV-illumination.

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8

El-Shamy, Omnia A. A. "Semiempirical Theoretical Studies of 1,3-Benzodioxole Derivatives as Corrosion Inhibitors." International Journal of Corrosion 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/8915967.

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The efficiency of 1,3-benzodioxole derivatives as corrosion inhibitors is theoretically studied using quantum chemical calculation and Quantitative Structure Activity Relationship (QSAR). Different semiempirical methods (AM1, PM3, MNDO, MINDO/3, and INDO) are applied in order to determine the relationship between molecular structure and their corrosion protection efficiencies. Different quantum parameters are obtained as the energy of highest occupied molecular orbitalEHOMO, the energy of the lowest unoccupied molecular orbitalELUMO, energy gapΔEg, dipole momentμ, and Mulliken charge on the at

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9

Raabe, Gerhard. "The Use of Quantum-Chemical Semiempirical Methods to Calculate the Lattice Energies of Organic Molecular Crystals. Part III: The Lattice Energy of Borazine (B3N3H6) and its Packing in the Solid State*." Zeitschrift für Naturforschung A 59, no. 9 (2004): 609–14. http://dx.doi.org/10.1515/zna-2004-0911.

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A previously presented quantum-chemical scheme has been used to calculate the lattice energies of borazine (B3N3H6), the low pressure polymorph of benzene (C6H6), and of borazine in the lowpressure benzene lattice utilizing some frequently used semiempirical methods (CNDO/2, INDO, MINDO/3, MNDO, AM1, PM3, MSINDO). With all methods the lattice energy of the title compound was found to be less favourable than that of isoelectronic benzene, which offers an explanation of the significantly lower melting point of B3N3H6. Calculation of the lattice energy of borazine in the crystal lattice of the lo

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10

Nomozov, A. K., Kh S. Beknazarov, Y. A. Geldiev, B. E. Babamurodov, N. Sh Muzaffarova, and S. G. Yuldashova. "SYNTHESIS OF PFG BRAND CORROSION INHIBITOR AND ITS QUANTUM CHEMICAL CALCULATION RESULTS." Chemical Problems 23, no. 3 (2025): 297–309. https://doi.org/10.32737/2221-8688-2025-3-297-309.

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This article examines the optimal conditions for synthesizing a new type of corrosion inhibitor based on p-paraphenylenediamine, formalin, and glycine. It was determined that the ideal mole ratio of the initial substances is 1:2:2 mol, and the optimal temperature range is between 40 and 65 degrees Celsius. The reaction efficiency under these optimal conditions was found to be 89.4%. The structure of the synthesized corrosion inhibitor was analyzed using IR spectra. Additionally, the Avogadro, Hyper Chem 8.01, Asselrys MS Modeling 3.0.1 software was used to perform quantum chemical calculations

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11

Fausto, Rui. "Calculation of vibrational frequencies of sulphur compounds using semiempirical molecular orbital methods (AM1, PM3, MNDO)." Journal of Molecular Structure 323 (July 1994): 267–77. http://dx.doi.org/10.1016/0022-2860(94)07989-7.

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12

Mudasir, Mudasir, Iqmal Tahir, and Ida Puji Astuti Maryono Putri. "QUANTITATIVE STRUCTURE AND ACTIVITY RELATIONSHIP ANALYSIS OF 1,2,4-THIADIAZOLINE FUNGICIDES BASED ON MOLECULAR STRUCTURE CALCULATED BY AM1 METHOD." Indonesian Journal of Chemistry 3, no. 1 (2010): 39–47. http://dx.doi.org/10.22146/ijc.21904.

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Quantitative structure-Activity relationship (QSAR) analysis of fungicides having 1,2,4-thiadiazoline structure based on theoretical molecular properties have been done. Calculation of the properties was conducted by semiempirical method AM1 and the activity of the compounds was taken from literature. Relationship analysis between fungicides activity (pEC50) and molecular properties was done using SPSS program. The QSAR analysis gave the best model as follows: pEC50 = 3.842 + (1.807x10-4) ET + (5.841x10-3) Eb - (5.689x10-2) DHf -0.770 log P + 1.144 a - 0.671 m + 9.568 GLOB - (5.54x10-2) MR. n=

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13

Maafi, Mounir, Jean-Jacques Aaron, Maria Carmen Mahedero та Francisco Salinas. "Evidence for the Formation of a Benzo[a]phenothiazine/2-Hydroxypropyl-β-Cyclodextrin Inclusion Complex Using a Fluorescence Method*". Applied Spectroscopy 52, № 1 (1998): 91–95. http://dx.doi.org/10.1366/0003702981942375.

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The inclusion complex of benzo[ a]-12H-phenothiazine (BPHT) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) was investigated in an aqueous solution containing 1% ethanol. It was found that the fluorescence emission intensity of the complexed fluorophore is six times larger than that of un complexed species and 1.5 times higher than that in pure ethanol. BPHT forms a 1:1 complex when included in the HP-β-CD. An association constant of the complex of 100±20 M−1 was calculated by using the Benesi–Hildebrand treatment of fluorescence emission data. A discussion based on AM1 semiempirical calculation

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14

Banerjee, Debashis, Asit Kumar Chandra, Manas Banerjee, and Sanjib Bagchi. "AM1 semiempirical MO calculation of specific solvation interaction: a scale for hydrogen bond donation ability of solvents." Journal of Molecular Structure: THEOCHEM 343 (November 1995): 167–71. http://dx.doi.org/10.1016/0166-1280(95)90549-9.

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15

Utomo, Suryadi Budi, Fajar Sanubari, Budi Utami, and Nanik Dwi Nurhayati. "Analysis of a Quantitative Relationship Between the Structure and Analgesic Activity of Meperidin Derivatives Using Semi-Empirical AM1 Method." JKPK (Jurnal Kimia dan Pendidikan Kimia) 2, no. 3 (2018): 158. http://dx.doi.org/10.20961/jkpk.v2i3.12092.

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<p>This research aims were to analize a quantitative relationship between the structure and analgesic activity of meperidine derivatives and to determine the Hansch equation between meperidine derivatives and their analgesic activity. The study was done by computer calculation (in sillico) using semiempirical method of AM1. The first stage was molecules modelling of meperidine derivative compounds, followed with performing the process of geometric optimization. The second step was to determine the descriptor value in the form of electronic, steric, and hydrophobic descriptors. The last s

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16

Mustofa, Mustofa, Iqmal Tahir, and Jumina Jumina. "QSAR STUDY OF 1,10-PHENANTHROLINE DERIVATIVES AS THE ANTIMALARIAL COMPOUNDS USING ELECTRONIC DESCRIPTORS BASED ON SEMIEMPIRICAL AM1 CALCULATION." Indonesian Journal of Chemistry 2, no. 2 (2010): 91–96. http://dx.doi.org/10.22146/ijc.21919.

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Quantitative Structure-Activity Relationship (QSAR) analysis of 1,10-phenantroline analogs as antimalarial drug has been conducted using atomic net charges (q) as predictors of their activity. Data of predictors are obtained from computational chemistry method using semi-empirical molecular orbital AM1 calculation. Antimalarial activities are taken as the activity of the drugs against plasmodium falciparum (FcM29-Cameroun) strain and are presented as the value of ln(1/IC50) where IC50 is an effective concentration inhibiting 50 % of the parasite growth. The results show that there is correlati

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17

Iswanto, Ponco, Mochammad Chasani, Harjono Harjono, Iqmal Tahir, Muhammad Hanafi, and Eva Vaulina YD. "NOVEL DESIGN OF CALANONE DERIVATIVES AS ANTI-LEUKEMIA COMPOUNDS BASED ON QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIP ANALYSIS." Indonesian Journal of Chemistry 11, no. 1 (2011): 31–36. http://dx.doi.org/10.22146/ijc.21416.

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Leukemia drug discovery based on calanone compound was conducted in previous research and produced 6 calanone derivatives. Most of them have lower activities against leukemia cell L1210 than pure calanone. A Quantitative Structure-Activity Relationship (QSAR) analysis is conducted in this work to find more active calanone derivatives. Six compounds were used as the material of the research because they already have anti-leukemia activity data expressed in Inhibitory Concentration of Fifty Percent Cell Lethal (IC50, in mg/mL). Calculation of predictors was performed by AM1 semiempirical method.

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18

Maksić, Z. B., D. Kovaček, and T. Šuste. "Semiempirical calculation of ESCA shifts in oxygen, nitrogen, fluorine and silicon inner core levels by the AM1-AMEP model." Journal of Molecular Structure 247 (July 1991): 305–12. http://dx.doi.org/10.1016/0022-2860(91)87080-2.

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19

Abu-Awwad, Fakhr M. "QSAR Study of the Biologically Active Organosulfurs in Natural Products." E-Journal of Chemistry 7, s1 (2010): S335—S343. http://dx.doi.org/10.1155/2010/763452.

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The biological activities of two sets of a total of 30 different polysulfides were investigated using QSAR. The semiempirical AM1 in Gaussian 2003 for windows was used to optimize the structures whereas a subsequent calculation of hundreds of various types of descriptors at the density functional (B3LYP/6-31G*) using CODESSA package was employed. The known 15-lipoxygenase inhibitory activity data (IC50) of 19 polysulfides out of the whole data set were correlated in a multiple linear regression procedures with the computed descriptors. Statistically, the most significant overall correlations w

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20

Miladiyah, Isnatin, Iqmal Tahir, Jumina Jumina, Sofia Mubarika, and Mustofa Mustofa. "Quantitative Structure-Activity Relationship Analysis of Xanthone Derivates as Cytotoxic Agents in Liver Cancer Cell Line HepG2." Molekul 11, no. 1 (2016): 143. http://dx.doi.org/10.20884/1.jm.2016.11.1.203.

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The study of xanthone derivatives as cytotoxic agents in cancer is increasing. This study was conducted to explore the Quantitative Structure-Activity Relationship (QSAR) of xanthones as cytotoxic agents in HepG2 cells, to find compounds with better potency. The data set were taken from the previous study, involving 26 xanthone derivates and their cytotoxic activities in Inhibitory Concentration 50% (IC50). The parameters (descriptors) were obtained from quantum mechanics calculation using semiempirical AM1 method and QSAR models determined with principle component regression, with log (1/IC50

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Öğretir, C., E. Açı́kkalp, and T. Güray. "Investigation of the acidity constants and Hammett relations of some oxazolo[4,5-b]pyridin derivatives using semiempirical AM1 quantum chemical calculation method." Journal of Molecular Structure: THEOCHEM 538, no. 1-3 (2001): 107–16. http://dx.doi.org/10.1016/s0166-1280(00)00653-9.

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22

Vaulina, Eva, and Ponco Iswanto. "MODEL QSAR SENYAWA FLUOROKUINOLON BARU SEBAGAI ZAT ANTIBAKTERI Salmonella thypimurium Eva Vaulina, Ponco Iswanto." Molekul 1, no. 1 (2006): 10. http://dx.doi.org/10.20884/1.jm.2006.1.1.17.

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Modelling of novel Fluoroquinolone derivates as antibacterial compund of Salmonella thypimurium was conducted. The research was done as an initial step in discovering some new Fluoroquinolone compounds which have higher activity to Salmonella thypimurium. There are 16 compunds that use as the material of the research and they already have antibacterial activity data that expressed in Minimal Inhibitory Concentration (MIC, mg/mL). Calculation was performed by semiempirical AM1 method. The QSAR model was determined by multilinear regression analysis, with Log MIC as dependent variable and the in

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23

Ford, George P., and Bingze Wang. "New approach to the rapid semiempirical calculation of molecular electrostatic potentials based on the am1 wave function: Comparison withab initio hf/6-31g* results." Journal of Computational Chemistry 14, no. 9 (1993): 1101–11. http://dx.doi.org/10.1002/jcc.540140911.

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24

J., K. Jain, and Gupta N. "Theoretical analysis of thermal isomerisation barrier of isocyanides into cyanides : A semiempirical approach." Journal of Indian Chemical Society Vol. 89, Jan 2012 (2012): 97—IOO. https://doi.org/10.5281/zenodo.5751751.

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Department of Chemistry, Agrawal Post Graduate College, Jaipur, Rajasthan, India <em>E-mail </em>: jkjain8962@yahoo.co.in Department of Chemistry, University of Rajasthan, Jaipur-302 004, Rajasthan, India <em>Manuscript received 25 June 2010, revised 18 May 2011, accepted 25 May 2011</em> AM1 semiempirical calculations for reactions have been performed and the effect of different substituents on thermal isomerisation barrier has been studied. As AM1 semiempirical calculations need much less time as compared to <em>ab initio</em> calculations, they have been employed to study the thermal rearra

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Buncel, Erwin, Richard M. Tarkka та Julian M. Dust. "AM1 studies on the stabilities of anionic σ-complex regioisomers: thermodynamics of regioselectivity in the reaction of methide, methoxide, and hydroxide anions with electron-deficient aromatics". Canadian Journal of Chemistry 72, № 7 (1994): 1709–21. http://dx.doi.org/10.1139/v94-216.

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Heats of formation (ΔHf) for a series of aromatics that are progressively more electron deficient (benzene, 6; nitrobenzene, 7; 4-fluoronitrobenzene, 8; 1,3-dinitrobenzene, 9; 2,4,6-trinitroanisole, 2; and 1,3,5-trinitrobenzene, 1) were determined by semiempirical AM1 calculations. As a probe of the factors that govern the regioselectivity exhibited in the formation of anionic σ-adducts (Meisenheimer complexes), experimental gas-phase ΔHf values for the prototypical oxygen and carbon nucleophiles (hydroxide, methoxide, and methide anions) were used in a thermochemical calculation along with th

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26

Mahboub, Radia. "Structural Conformational Study of Eugenol Derivatives Using Semiempirical Methods." Advances in Chemistry 2014 (October 20, 2014): 1–5. http://dx.doi.org/10.1155/2014/490358.

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We investigated the conformational structure of eugenol and eugenyl acetate under torsional angle effect by performing semiempirical calculations using AM1 and PM3 methods. From these calculations, we have evaluated the strain energy of conformational interconversion. To provide a better estimate of stable conformations, we have plotted the strain energy versus dihedral angle. So, we have determined five geometries of eugenol (three energy minima and two transition states) and three geometries of eugenyl acetate (two energy minima and one transition state). From the molecular orbital calculati

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27

LUKEŠ, VLADIMÍR, ROLAND ŠOLC, MARIO BARBATTI, HANS LISCHKA, and HARALD-FRIEDRICH KAUFFMANN. "TORSIONAL POTENTIALS AND FULL-DIMENSIONAL SIMULATION OF ELECTRONIC ABSORPTION SPECTRA OF para-PHENYLENEVINYLENE OLIGOMERS USING SEMIEMPIRICAL HAMILTONIANS." Journal of Theoretical and Computational Chemistry 09, no. 01 (2010): 249–63. http://dx.doi.org/10.1142/s0219633610005645.

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A systematic study of torsional potential curves in electronic ground state based on second-order Møller–Plesset energy (MP2), density functional theory (DFT), and Austin mode 1 (AM1) methods is presented for para-phenylenevinylene oligomers constructed from two to four aromatic rings. The semiempirical AM1 approach gives the correct location of potential energy minima in comparison with the reference MP2 calculations and literature data. However, the semiempirical AM1 energy barriers at perpendicular orientation are ca. 30% smaller than the MP2 ones. The DFT calculations indicate optimal plan

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Labidi, N. S. "Nonlinear Optical Properties of Novel Mono-O-Hydroxy Bidentate Schiff Base: Quantum Chemical Calculations." International Journal of Metals 2013 (December 17, 2013): 1–5. http://dx.doi.org/10.1155/2013/964328.

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The semiempirical AM1 SCF method is used to study the first static hyperpolarizabilities β of some novel mono-O-Hydroxy bidentate Schiff base in which electron donating (D) and electron accepting (A) groups were introduced on either side of the Schiff base ring system. Geometries of all molecules were optimized at the semiempirical AM1. The first static hyperpolarizabilities of these molecules were calculated using Hyperchem package. To understand this phenomenon in the context of molecular orbital picture, we examined the molecular HOMO and molecular LUMO generated via Hyperchem. The study re

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Pranowo, Harno Dwi, Iqmal Tahir, and Ajidarma Widiatmoko. "QUANTITATIVE RELATIONSHIP OF ELECTRONIC STRUCTURE AND INHIBITION ACTIVITY OF CURCUMIN ANALOGS ON ETHOXYRESORUFIN o-DEALKYLATION (EROD) REACTION." Indonesian Journal of Chemistry 7, no. 1 (2010): 78–82. http://dx.doi.org/10.22146/ijc.21717.

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Electronic structure and inhibition activity relationship study of curcumin analogs has been established for 29 curcumin analogs on Ethoxyresorufin O-Dealkylation (EROD) reaction using atomic net charge descriptor based on AM1 semiempirical calculations. The QSAR (Quantitative Structure and Activities Relationships) equation model was determined by statistical parameter from multiple regression analysis and leave-one-out cross validation method. The best QSAR equation was described: Keywords: curcumin, QSAR, descriptor, atomic net charge, semiempirical methods.

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Das, Gourab Kanti, Bijali Choudhury, Kalpita Das, and Basudeb Prasad Das. "Vilsmeier Reaction on Carbazole: Theoretical and Experimental Aspects." Journal of Chemical Research 23, no. 3 (1999): 244–45. http://dx.doi.org/10.1177/174751989902300337.

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The pathway of the Vilsmeier reaction on carbazole has been studied by AM1 semiempirical MO calculations, which includes the characterization of the various transition structures; an experimental study of the actual reaction shows the formation of diformyl derivative along with a monoformyl derivative.

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Azizian, Javad, Hossain Fallah-Bagher-Shaidaei, and Hassan Kefayati. "AM1 Study of the Conformational Properties of Bicyclo[3.3.3]Undecane and its N-Bridgehead Derivatives." Journal of Chemical Research 2003, no. 4 (2003): 228–29. http://dx.doi.org/10.3184/030823403103173570.

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AM1 semiempirical SCF MO calculations show that the BC conformation is the most stable form of bicyclo[3.3.3]undecane (1) and its N-bridgehead derivatives (2 and 3), whereas the corresponding BB conformations are calculated to be from 4.3 kcal/mol in (3) to 7.1 kcal/mol in (1) higher in energy.

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Chmielewski, Dietmar, Nick Henry Werstiuk, and Timothy A. Wildman. "Conformational preferences and barriers to internal rotation in fluorothioanisoles from long-range spin–spin couplings, photoelectron spectroscopy, and semiempirical molecular orbital calculations." Canadian Journal of Chemistry 71, no. 10 (1993): 1741–50. http://dx.doi.org/10.1139/v93-217.

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The conformational preferences and barriers to internal rotation about the S—C(phenyl) bond have been investigated for thioanisole and its 2-fluoro, 2,6- and 3,5-difluoro, and 2,3,5,6-tetrafluoro derivatives. Measurements of long-range spin–spin couplings between the methyl carbon and the para ring proton indicate that the 2-fluoro and 3,5-difluoro compounds prefer conformations with all heavy atoms coplanar. The 2,6-difluoro and 2,3,5,6-tetrafluoro compounds prefer conformations in which the methyl carbon lies in or near the plane perpendicular to the aromatic ring. Semiempirical molecular or

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Karaman, Rafik. "Accelerations in the Lactonization of Trimethyl Lock Systems Are due to Proximity Orientation and not to Strain Effects." Research Letters in Organic Chemistry 2009 (March 26, 2009): 1–5. http://dx.doi.org/10.1155/2009/240253.

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DFT at B3LYP/6-31G(d,p) and HF at 6-31G and AM1 semiempirical calculations of thermodynamc and kinetic parameters for the trimethyl lock system (an important enzyme model) indicate that the remarkable enhancement in the lactonizations is largely the result of a proximity orientation as opposed to the currently advanced strain effect.

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Margheritis, C., та C. Sinistri. "β-cyclodextrine and Water: Semiempirical Calculations". Zeitschrift für Naturforschung A 51, № 8 (1996): 950–56. http://dx.doi.org/10.1515/zna-1996-0810.

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Abstract AM1 and PM3 calculations were carried out on ß-cyclodextrine (ß-CD) undecahydrate in the experimental conformation at 120 K. The calculated ß-CD/water interaction energies are very small and indicative for each water molecule of an unfavorable condition in respect to that of pure water. The conformationally optimized system was also studied: ß-CD appears highly symmetrical with negligible dipole moment, mainly because of the circular arrangement of the single vectors. Primary hydroxyls can easily rotate, while the secondary ones are stabilized by heteroannular hydrogen bonds and homoa

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35

Esser, Josef, Jörg Fleischhauer, Herbert Frauenrath, Christoph Jansen, Bernd Kramer, and Jan Runsink. "Semiempirische Rechnungen zur Bestimmung der Konformation des 4,5-Dihydro-1,3-dioxepins und seines 2-Methyl-Derivats." Zeitschrift für Naturforschung A 49, no. 6 (1994): 714–18. http://dx.doi.org/10.1515/zna-1994-0610.

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Abstract Semiempirical Calculations for the Determination of the Conformation of 4,5-dihydro-1,3-dioxepine and its 2-methyl derivative The possible conformations of the title compounds have been studied with the semiempirical methods MNDO and AM1. In the local minima, the vibration frequencies have been calculated to get the free enthalpy of each conformer and its equilibrium concentration. The energy minimized structures and the calculated thermodynamical values are compared with experimental results. From our investigations we conclude that the chair conformation is preferred. In the case of

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36

Fabian, Walter M. F., and Gert Kollenz. "Semiempirical AM1 calculations of the substituent effect on acetylketene dimerizations." Journal of Molecular Structure: THEOCHEM 313, no. 2 (1994): 219–30. http://dx.doi.org/10.1016/0166-1280(94)85004-6.

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37

Davis, Larry P., Larry W. Burggraf, and Donn M. Storch. "Hydration of small anions: Calculations by the AM1 semiempirical method." Journal of Computational Chemistry 12, no. 3 (1991): 350–58. http://dx.doi.org/10.1002/jcc.540120308.

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38

Chen, Zhongfang, Keqin Ma, Yinming Pan, Xuezhuang Zhao, and Auchin Tang. "Theoretical studies of heterofullerenes C68X2 (X = N, B)." Canadian Journal of Chemistry 77, no. 3 (1999): 291–98. http://dx.doi.org/10.1139/v99-016.

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A systematic investigation on the molecular structures of the possible energetically favored isomers of C68X2 (X = N, B) has been performed using the semiempirical MNDO, AM1, and PM3 methods. The most stable isomer of C68X2 was computed, and the static properties such as heats of atomization, ionization potentials, electron affinities, absolute electronegativities, and global hardness have been predicted theoretically. The proposition that the changes of hybridization from sp2 to sp3 are the predominant factors of the regiochemistry for both C60X2 and C58X2 are supported by the calculations, a

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39

Ouédraogo, Jean Claude W., Edouard Tapsoba, Sié Faustin Sib, and Yvonne Libona Bonzi-Coulibaly. "Styrylpyrylium Salts: and NMR High-Resolution Spectroscopy (1D and 2D)." International Journal of Spectroscopy 2010 (June 29, 2010): 1–6. http://dx.doi.org/10.1155/2010/246821.

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and NMR high-resolution spectroscopy (1D and 2D) (, -COSY, HSQC, HMBC) for four styrylpyrylium perchlorates were carried out and signal attributions are reported. Chemical shifts observed on NMR spectra for the styrylpyrylium salts were compared with net atomic charge for carbon obtained by AM1 semiempirical calculations. The position of the styryl group present low effect on chemical shifts for carbon atoms, while the presence of methyl group led to the unshielding of the substituted carbon.

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Rasimas, J. P., and G. J. Blanchard. "Understanding the Electronic Properties of Glycosylated Chromophores Using AM1 Semiempirical Calculations." Journal of Physical Chemistry 98, no. 49 (1994): 12949–57. http://dx.doi.org/10.1021/j100100a023.

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41

Werstiuk, N. H., R. S. Brown, and Q. Wang. "An AM1 calculational study of the protonation and reactions of 3,4-dihydro-2-oxo-1,4-ethanoquinoline, 3,4-dihydro-2-oxo-1,4-propanoquinoline, 3,3,4,5-tetrahydro-2-oxo-1,5-ethanobenzazepine, 3,3,4,5-tetrahydro-2-oxo-1,5-propanobenzazepine, and N-methyl-4-bromo-2-methylacetanilide." Canadian Journal of Chemistry 74, no. 4 (1996): 524–32. http://dx.doi.org/10.1139/v96-057.

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The gas phase N- and O-protonation of distorted amides 3,4-dihydro-2-oxo-1,4-ethanoquinoline (1a), 3,4-dihydro-2-oxo-1,4-propanoquinoline (1b), 3,3,4,5-tetrahydro-2-oxo-1,5-ethanobenzazepine (1c), and 3,3,4,5-tetrahydro-2-oxo-1,5-propanobenzazepine (1d) and normal amides 4-bromo-2,N-dimethylacetanilide (5a) and 2,N-dimethylacetanilide (5b), along with the N-protonation of benzoquinuclidine (7), has been studied calculationally at the semiempirical level of theory with AM1. Calculated enthalpies of N- and O-protonation (proton affinities) indicate that 1a, 1b, and 1c should protonate on nitroge

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42

Marques, Marcelo Volpatto, Denis Russowsky, and L. M. A. Fontoura. "ANÁLISE CONFORMACIONAL DE COMPOSTOS DE BIGINELLI COM ATIVIDADE ANTINEOPLÁSICA." Eclética Química Journal 35, no. 4 (2018): 33. http://dx.doi.org/10.26850/1678-4618eqj.v35.4.2010.p33-38.

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Dihydropyrimidinones, such as monastrol and analogues, are heterocycles with known antineoplastic activity. Conformational analysis represents an important preliminary step in structure-activity correlation studies. Herein we describe the conformational analysis of monastrol and analogues by AM1 semiempirical and ab initio HF/6-31G* calculations. Four equilibrium geometries were found (s-cis/ap, s-cis/sp, strans/ap and s-trans/sp), and the important internal rotations were those of the ab-unsaturated carbonyl system and of the aryl group connected to the heterocycle

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43

Posokhov, Yevgen, Sule Erten, Ömer Koz, H. AnIl, Süheyla KIrmIzIgül, and SIddIk Içli. "UV/VIS spectral properties of novel natural products from Turkish lichens." International Journal of Photoenergy 7, no. 1 (2005): 27–35. http://dx.doi.org/10.1155/s1110662x0500005x.

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UV/VIS spectral characteristics of three new biologically active natural products, isolated from Turkish lichens, have been investigated in solvents of various polarity and proton donating ability. The effect of the solvent on spectral characteristics has been estimated. Quantum chemical calculations with the optimization of molecular geometry were done with the full-valent semiempirical methods AM1 and PM3 for conformational analysis and in order to discuss the charge distributions and dipole moments in the ground and in the excited states.

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Jefferson, E. A., A. J. Kresge, and S. W. Paine. "Acid-catalyzed hydrolysis of 4-diazo-isothiochroman-3-one. Comparison with the acyclic analog and the corresponding oxygen system." Canadian Journal of Chemistry 75, no. 1 (1997): 56–59. http://dx.doi.org/10.1139/v97-008.

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The acid-catalyzed hydrolysis of the cyclic diazothiolactone, 4-diazoisochroman-3-one (3) was found to occur with the hydronium-ion isotope effect, [Formula: see text] and to give the ring-contracted product, 1,3-dihydrobenzo[c]thiophene-1-carboxylic acid (4). This shows that protonation of the diazo carbon atom occurs in the rate-determining step and that the reaction also involves migration of the thio group. The hydronium-ion catalytic coefficient for this reaction, [Formula: see text], is 45 times less than that for hydrolysis of its acyclic thio ester analog, S-methyl phenyldiazothioaceta

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45

Ishida, Hiroyuki, Yoshihiro Kubozono, Setsuo Kashino, and Ryuichi Ikeda. "Structural Parameters and Internal Rotational Barriers of tert-Butylammonium Ion: AM1 and ab initio Calculations." Zeitschrift für Naturforschung A 47, no. 12 (1992): 1255–56. http://dx.doi.org/10.1515/zna-1992-1215.

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Semiempirical and ab initio MO calculations were performed to estimate the structural parameters of tert-butylammonium ion and its potential energies for the internal rotation of the CH3 and NH3+ groups. The barrier height for the rotation of NH3+ was found to be lower than for that of CH3 , corresponding to the C - N bond being longer than the C - C bond.

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Janoschek, Rudolf, Walter M. F. Fabian, Gert Kollenz, and C. Oliver Kappe. "Conformation and reactivity of ?-oxo-ketenes:Ab initio and semiempirical (AM1, PM3) calculations." Journal of Computational Chemistry 15, no. 2 (1994): 132–43. http://dx.doi.org/10.1002/jcc.540150203.

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47

ERKOÇ, ŞAKIR. "STRUCTURAL AND ELECTRONIC PROPERTIES OF CARBON NANOTUBES." International Journal of Modern Physics C 11, no. 01 (2000): 175–82. http://dx.doi.org/10.1142/s0129183100000158.

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The structural and electronic properties of optimized open-ended single-wall carbon nanotubes with zigzag geometry have been investigated. The calculations were performed using molecular mechanics, extended Hückel, and AM1–RHF semiempirical molecular orbital methods. It has been found that the density of states of the zigzag model is sensitive to the tube size and changes as the tube length increases. On the other hand the energetics of the tube shows an almost linear dependence to the tube length, and a converging characteristics with respect to the number of hexagons forming the tube.

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48

Miron, Neculai Doru, Patrice Woisel, Georgiana G. Surpateanu, Gérard Vergoten, Ludovic Depature, and Gheorghe Surpateanu. "Benzotriazolium ylides: Experimental and theoretical study on the tautomeric equilibrium of monosubstituted benzotriazolium ylides." Canadian Journal of Chemistry 81, no. 5 (2003): 350–56. http://dx.doi.org/10.1139/v03-050.

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The biphenacyl benzotriazolium salts 12 give a tautomeric equilibrium 13[Formula: see text]14 in the presence of triethylamine (TEA) or NaOH. The evaluation of this tautomeric equilibrium has been studied using a dynamic NMR analysis and a new synthetic procedure of disubstituted benzotriazolium ylides 15 and 16, which have in their structures a picryl fragment. This study also includes a theoretical analysis on the reactivity of salts 12ac and the thermodynamical stability of tautomeric forms 13 and 14 by AM1 and PM3 procedure methods.Key words: synthesis, salts, ylides, semiempirical calcul

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49

Shephard, MJ, and MN Paddonrow. "A Caveat Concerning the Use of the AM1 and PM3 Semiempirical Methods in Calculating Conformational Preferences in Acyclic Amines and Saturated Azaheterocycles." Australian Journal of Chemistry 46, no. 4 (1993): 547. http://dx.doi.org/10.1071/ch9930547.

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A theoretical investigation of the conformational analysis of several acyclic amines, N- alkylated saturated azaheterocycles and alkylcyclohexanes (alkyl = Me, Et, isopropyl, t-butyl) has been carried out by using the MNDO, AM1 and PM3 semiempirical methods. It is found that all three methods correctly predict, qualitatively, the conformational preferences in alkylcyclohexanes, although the PM3 method underestimates the conformational energy for the t-butyl group by as much as 13 kJ/mol. Both AM1 and PM3 overestimate the conformational energy of the nitrogen lone pair to the extent that it exc

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50

Gajanan, Pandey, Shrivastava Snehika, and K. Sharma Harendra. "Theoretical investigations of synthesized Schiff base ligand derived from S-alkyldithiocarbazate." Journal of Indian Chemical Society Vol. 91, Nov 2014 (2014): 2009–18. https://doi.org/10.5281/zenodo.5734240.

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Department of Applied Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow-226 025, Uttar Pradesh, India <em>E-mail</em> : pandeygajanan@rediffmail.com Department of Chemistry, I.P.S. College of Technology and Management, Gwalior-474 001, Madhya Pradesh, India Indira Gandhi Academy of Environmental Education, Research and Ecoplanning, Jiwaji University, Gwalior-474 011, Madhya Pradesh, India <em>E-mail</em> : drsharmahk@yahoo.com <em>Manuscript received online 26 March 2014, accepted 03 June 2014</em> 4-Hydroxy-3-methoxy Schiff base derived from S-methyldithiocarbazate was prepared adopti

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