Search results

Search for "quantum chemical calculations" in Full Text gives 98 result(s) in Beilstein Journal of Organic Chemistry.

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

  • Thanh-Tuân Bui,
  • Fabrice Goubard,
  • Malika Ibrahim-Ouali,
  • Didier Gigmes and
  • Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

Graphical Abstract
  • ° between the donor unit and the nearby phenylene linker for T29 and T30 was confirmed by quantum chemical calculations. Resulting from the almost perfect orthogonality, a good confinement of the electronic density of the two orbitals was obtained with a HOMO level predominantly located on the donor and a
PDF
Album
Review
Published 30 Jan 2018

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

  • Aleksey A. Vasilev,
  • Meglena I. Kandinska,
  • Stanimir S. Stoyanov,
  • Stanislava B. Yordanova,
  • David Sucunza,
  • Juan J. Vaquero,
  • Obis D. Castaño,
  • Stanislav Baluschev and
  • Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

Graphical Abstract
  • the newly synthesized dyes as DNA fluorogenic binders. A further study of several aspects (including quantum chemical calculations and experimental studies on the DNA binding mechanism) should be carried out on these dyes in order to exploit in details their promising properties. Experimental
PDF
Album
Supp Info
Full Research Paper
Published 28 Dec 2017

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

  • Jan Podlesný,
  • Lenka Dokládalová,
  • Oldřich Pytela,
  • Adam Urbanec,
  • Milan Klikar,
  • Numan Almonasy,
  • Tomáš Mikysek,
  • Jaroslav Jedryka,
  • Iwan V. Kityk and
  • Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

Graphical Abstract
  • generation. The experimental data were completed by quantum-chemical calculations and structure–property relationships were elucidated. Keywords: calculations; diketopyrrolopyrrole; electrochemistry; electronic spectra; push–pull; third-harmonic generation; Introduction Known for more than 40 years
PDF
Album
Supp Info
Full Research Paper
Published 08 Nov 2017

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

  • Yaroslav D. Boyko,
  • Valentin S. Dorokhov,
  • Alexey Yu. Sukhorukov and
  • Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

Graphical Abstract
  • phosphinyl nitrosoalkenes NSA15 (derived from the corresponding α-bromooximes) with electron-rich nitrogen heterocycles to give adducts 69 is described and the comparison of electrophilic aromatic substitution (1) and cycloaddition (2) routes is discussed [59] (Scheme 24). Quantum-chemical calculations
PDF
Album
Review
Published 23 Oct 2017

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

  • Leonid S. Kikot',
  • Catherine Yu. Kulygina,
  • Alexander Yu. Lyapunov,
  • Svetlana V. Shishkina,
  • Roman I. Zubatyuk,
  • Tatiana Yu. Bogaschenko and
  • Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

Graphical Abstract
  • paraquat (7) in solution is well correlated with the data for these complexes in the crystalline state revealed by quantum chemical calculations [41] except complexes with paraquat derivative 10 (Table 4). The calculated data show that the main contribution to the stabilization of the complexes in the
  • with clips 1–6. Complex stability constants of molecular clips 1–5 with guests 7–10 in acetonitrile at 20 °C. Contribution of polyether oxygen atoms of molecular clips 1–5 to the binding of paraquat. The host–guest interaction energies are estimated by quantum chemical calculations (b97-D3/def2-tzvp
  • (Figure 7). Within the row molecules are arranged by π–π stacking interactions between the side aromatic fragments of the clips with a centroid–centroid distance in the range of 3.51–3.71 Å. There are acetonitrile solvate molecules and hexafluorophosphate anions between neighboring rows. Quantum chemical
PDF
Album
Supp Info
Full Research Paper
Published 04 Oct 2017

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

  • Daria G. Selivanova,
  • Alexei A. Gorbunov,
  • Olga A. Mayorova,
  • Alexander N. Vasyanin,
  • Igor V. Lunegov,
  • Elena V. Shklyaeva and
  • Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

Graphical Abstract
  • comparison with the ground state takes place, as evidenced by the quantum-chemical calculations carried out with the help of the Fire Fly package [30][31] on a PGU Tesla supercomputer. All calculations of the dipole moments, HOMO and LUMO energies were performed on the B3LYP/6-31G* level for the gas phase
PDF
Album
Supp Info
Full Research Paper
Published 10 Aug 2017

Conformational study of L-methionine and L-cysteine derivatives through quantum chemical calculations and 3JHH coupling constant analyses

  • Weslley G. D. P. Silva,
  • Carolyne B. Braga and
  • Roberto Rittner

Beilstein J. Org. Chem. 2017, 13, 925–937, doi:10.3762/bjoc.13.94

Graphical Abstract
  • analysis; cysteine; methionine; NMR spectroscopy; quantum chemical calculations; Introduction Amino acids constitute the building blocks of proteins and peptides, which play an important role in numerous biological processes [1][2]. However, their studies in both isolated and condensed phases have been
  • quantum chemical calculations [16][17][18][19]. In spite of these many studies performed, there is still a lack of information about the effects that rule their conformational isomerism. Additionally, the conformational flexibility of both amino acids leads to a variety of low energy geometries, which
  • insights about the main conformers and the operating effects in the compounds, both in isolated phase and in various aprotic solvents, 1H NMR spectroscopy and quantum chemical calculations, including natural bond orbitals (NBO), quantum theory of atoms in molecules (QTAIM), and noncovalent interactions
PDF
Album
Supp Info
Full Research Paper
Published 17 May 2017

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

  • Anna S. Zalivatskaya,
  • Dmitry S. Ryabukhin,
  • Marina V. Tarasenko,
  • Alexander Yu. Ivanov,
  • Irina A. Boyarskaya,
  • Elena V. Grinenko,
  • Ludmila V. Osetrova,
  • Eugeniy R. Kofanov and
  • Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

Graphical Abstract
  • nitrogen may be protonated depending on the substituents attached to the heterocyclic system [50]. To investigate this issue in more detail we undertook a theoretical study on the protonation of 5-(2-phenylethenyl)-3-phenyl-1,2,4-oxadiazole (1a) by quantum-chemical calculations. Table 1 contains data
PDF
Album
Supp Info
Full Research Paper
Published 11 May 2017

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

  • Anastasia S. Kostyuchenko,
  • Tatyana Yu. Zheleznova,
  • Anton J. Stasyuk,
  • Aleksandra Kurowska,
  • Wojciech Domagala,
  • Adam Pron and
  • Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

Graphical Abstract
  • induce non-planarity due to steric hindrance, which lowers the effective conjugation. This problem will be discussed in detail in the section devoted to quantum chemical calculations. When excited by UV light, all studied compounds emit blue (468, 473 nm) or bluish-green (499, 501) light (Table 2
  • observed in D–A–D-type conjugated molecules [28]. DFT calculations To gain a deeper understanding of the electronic and photophysical properties of the synthesized 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles we have performed quantum-chemical calculations for four
PDF
Album
Supp Info
Full Research Paper
Published 17 Feb 2017

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

  • Patrick T. Campos,
  • Leticia V. Rodrigues,
  • Andrei L. Belladona,
  • Caroline R. Bender,
  • Juliana S. Bitencurt,
  • Fernanda A. Rosa,
  • Davi F. Back,
  • Helio G. Bonacorso,
  • Nilo Zanatta,
  • Clarissa P. Frizzo and
  • Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

Graphical Abstract
  • quantum-chemical calculations were used to understand the regiochemistry of the obtained products. Results and Discussion β-Enaminodiketone 1, which is a key precursor for the synthesis of polyazaheterocyclic compounds, was synthesized by methods previously described by our research group [17][18][19][20
PDF
Album
Supp Info
Full Research Paper
Published 10 Feb 2017

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

  • Lukas J. Patalag and
  • Daniel B. Werz

Beilstein J. Org. Chem. 2016, 12, 2739–2747, doi:10.3762/bjoc.12.270

Graphical Abstract
  • a Wittig salt with a longer alkyl chain the synthesis of the fatty acid 11d with a chain of 21 carbon atoms in addition to the BTD unit was equally feasible. Spectroscopic properties and quantum chemical calculations If one follows the oligoene chain and includes the two s-cis-shaped double bonds of
PDF
Album
Supp Info
Full Research Paper
Published 14 Dec 2016

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

  • Ilya V. Efimov,
  • Marsel Z. Shafikov,
  • Nikolai A. Beliaev,
  • Natalia N. Volkova,
  • Tetyana V. Beryozkina,
  • Wim Dehaen,
  • Zhijin Fan,
  • Viktoria V. Grishko,
  • Gert Lubec,
  • Pavel A. Slepukhin and
  • Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

Graphical Abstract
  • with inverse electron demand, similarly to the reaction of enamines with azides [37]. To gain deeper insights into the mechanism of the cycloaddition between nitrile oxides and enamines, quantum chemical calculations were carried out using the Gaussian 09 [38] programs package at B3LYP/def2-TZVP [39
PDF
Album
Supp Info
Full Research Paper
Published 15 Nov 2016

Organometallic chemistry

  • Bernd F. Straub,
  • Rolf Gleiter,
  • Claudia Meier and
  • Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 2216–2221, doi:10.3762/bjoc.12.213

Graphical Abstract
  • improved understanding of this industrially important process was achieved by a combination of ligand design for the rhodium catalysts, kinetic studies, and high-level quantum-chemical calculations [126][135][142][145][146][152][155]. In 2006, he initiated the foundation of the “Catalysis Research
PDF
Album
Editorial
Published 19 Oct 2016

Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

  • Dmitry S. Ryabukhin,
  • Dmitry N. Zakusilo,
  • Mikhail O. Kompanets,
  • Anton A.Tarakanov,
  • Irina A. Boyarskaya,
  • Tatiana O. Artamonova,
  • Mikhail A. Khohodorkovskiy,
  • Iosyp O. Opeida and
  • Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

Graphical Abstract
  • (Scheme 1). All species A, B, C, and D may play a role as reactive intermediates derived from 1a and 2 in superacids. To estimate the electrophilic properties of cations A, B, C, and D we performed quantum chemical calculations by the DFT method (Table 1). HOMO and LUMO energies, global electrophilicity
PDF
Album
Supp Info
Full Research Paper
Published 05 Oct 2016

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

  • Valeria Corne,
  • Ariel M. Sarotti,
  • Carmen Ramirez de Arellano,
  • Rolando A. Spanevello and
  • Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

Graphical Abstract
  • , Universidad de Valencia, Valencia 46100, Spain 10.3762/bjoc.12.158 Abstract Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl–vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence
PDF
Album
Supp Info
Full Research Paper
Published 28 Jul 2016

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

  • Daria Yu. Dzhons and
  • Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

Graphical Abstract
  • to quantum-chemical calculations, the energy barrier of this rearrangement is approximately 40 kJ mol−1 [51], with the limiting step being the formation of B. Therefore, the direction of this reaction solely depends on the conversion of A and formation of C. Dyall et al. [52][53] have proposed a
PDF
Album
Supp Info
Full Research Paper
Published 04 May 2016

Recent highlights in biosynthesis research using stable isotopes

  • Jan Rinkel and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

Graphical Abstract
  • subsequent 1,2-hydride migration to 63 followed by ring closure gives 64, which is deprotonated to give pentalenene (65). Quantum chemical calculations led to the suggestion of the protoilludyl cation 66 as central intermediate between 61 and 64 (pathway B), which is directly formed from 61 [72
PDF
Album
Review
Published 09 Dec 2015

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

  • Mohamed Yacine Ameur Messaoud,
  • Ghenia Bentabed-Ababsa,
  • Madani Hedidi,
  • Aïcha Derdour,
  • Floris Chevallier,
  • Yury S. Halauko,
  • Oleg A. Ivashkevich,
  • Vadim E. Matulis,
  • Laurent Picot,
  • Valérie Thiéry,
  • Thierry Roisnel,
  • Vincent Dorcet and
  • Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

Graphical Abstract
  • recently [42][52]. The results of quantum chemical calculations on CH acidity of the different N-arylated pyrroles 1 and indoles 2, obtained both for THF solution (Figure 5) and gas phase (see Supporting Information File 1), are presented in the current paper. A potential acidity of the methoxy groups in
PDF
Album
Supp Info
Full Research Paper
Published 24 Aug 2015

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

  • Adriana K. Slavova-Kazakova,
  • Silvia E. Angelova,
  • Timur L. Veprintsev,
  • Petko Denev,
  • Davide Fabbri,
  • Maria Antonietta Dettori,
  • Maria Kratchanova,
  • Vladimir V. Naumov,
  • Aleksei V. Trofimov,
  • Rostislav F. Vasil’ev,
  • Giovanna Delogu and
  • Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

Graphical Abstract
  • quantum chemical calculations (see section “Model 4: DFT calculations”) for BDE of 13 and studied compounds in water medium confirm our hypothesis. It is noteworthy that the literature data for individual phenolic compounds acquired with ORAC as a model system are rather poor in comparison with the data
  • to act as chain-breaking antioxidants. The experimental results (models 1–3) obtained are qualitatively supported by quantum chemical calculations (model 4). Dimers showed higher activity than the corresponding monomers in the experiments in homogeneous solutions (models 1 and 2) and similar activity
PDF
Album
Supp Info
Full Research Paper
Published 11 Aug 2015

On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation

  • Andrey S. Mereshchenko,
  • Alexey V. Ivanov,
  • Viktor I. Baranovskii,
  • Grzegorz Mloston,
  • Ludmila L. Rodina and
  • Valerij A. Nikolaev

Beilstein J. Org. Chem. 2015, 11, 504–513, doi:10.3762/bjoc.11.57

Graphical Abstract
  • -oxathiole 3 and alkene 5 (4:1) was formed, whereas at 80 °C, product 5 was formed exclusively (81%) [20]. In order to explain the obtained results and to elucidate the reaction pathway (which governs reactions of DDC 1 with aromatic and aliphatic thioketones 2), detailed quantum-chemical calculations of the
  • transient thiirane S-sulfide 8’d (step d), it is most likely that it follows the pathway proposed for the spontaneous desulfurization of matrix-isolated oxathiiranes [32]. Conclusion The quantum-chemical calculations show that the initial step of the 1,3-dipolar cycloaddition of acyclic 2-diazo-1,3
  • relative energy of the reagents, reaction intermediates, transition states, and reaction products on the potential energy surfaces were carried out. The results of the performed study are summarized and discussed in the present publication. Results and Discussion The subjects of the quantum-chemical
PDF
Album
Supp Info
Full Research Paper
Published 20 Apr 2015

Synthesis and characterization of a new photoinduced switchable β-cyclodextrin dimer

  • Florian Hamon,
  • Claire Blaszkiewicz,
  • Marie Buchotte,
  • Estelle Banaszak-Léonard,
  • Hervé Bricout,
  • Sébastien Tilloy,
  • Eric Monflier,
  • Christine Cézard,
  • Laurent Bouteiller,
  • Christophe Len and
  • Florence Djedaini-Pilard

Beilstein J. Org. Chem. 2014, 10, 2874–2885, doi:10.3762/bjoc.10.304

Graphical Abstract
  • of 1 atm and a temperature of 300 K. In order to obtain representative ensembles of conformations for the two bis-CD systems, molecular configurations from MD trajectories were clustered. Ab initio calculations were performed with the Gaussian 09 program [50] to perform quantum chemical calculations
PDF
Album
Full Research Paper
Published 04 Dec 2014

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

  • Alexander F. Khlebnikov,
  • Mikhail S. Novikov,
  • Yelizaveta G. Gorbunova,
  • Ekaterina E. Galenko,
  • Kirill I. Mikhailov,
  • Viktoriia V. Pakalnis and
  • Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

Graphical Abstract
  • really formed in this reaction?” and “What is their reactivity?” To this end, we carried out quantum-chemical calculations of the formation and the ring opening of isoxazolium N-ylides. Probing the type of the mechanistic scheme of the 2H-1,3-oxazine formation was also conducted by searching for the
PDF
Album
Supp Info
Full Research Paper
Published 14 Aug 2014

Substitution effect and effect of axle’s flexibility at (pseudo-)rotaxanes

  • Friedrich Malberg,
  • Jan Gerit Brandenburg,
  • Werner Reckien,
  • Oldamur Hollóczki,
  • Stefan Grimme and
  • Barbara Kirchner

Beilstein J. Org. Chem. 2014, 10, 1299–1307, doi:10.3762/bjoc.10.131

Graphical Abstract
  • substitution with different functional groups and of molecular flexibility by changing within the axle from a single C–C bond to a double C=C bond. Therefore, we present static quantum chemical calculations at the dispersion-corrected density functional level (DFT-D3) for several Leigh-type rotaxanes. The
  • from a more bowed axle with respect to the wheel. Conclusion We investigated several rotaxanes by static quantum chemical calculations in order to gain insight into the interplay of different non-covalent interactions. Therefore, we studied the substitution of the rotaxanes with different functional
PDF
Album
Supp Info
Full Research Paper
Published 05 Jun 2014

cistrans Isomerization of silybins A and B

  • Michaela Novotná,
  • Radek Gažák,
  • David Biedermann,
  • Florent Di Meo,
  • Petr Marhol,
  • Marek Kuzma,
  • Lucie Bednárová,
  • Kateřina Fuksová,
  • Patrick Trouillas and
  • Vladimír Křen

Beilstein J. Org. Chem. 2014, 10, 1047–1063, doi:10.3762/bjoc.10.105

Graphical Abstract
  • isomerization can be initiated by the formation of coordination complexes at either C-4=O or O-1 (see Scheme 5). Nevertheless, based on the quantum chemical calculations (Table 3 and Table 4) together with the representation of cis-isomers in the isomerization mixture, the most stable coordination complex IIa
  • of taxifolin isomerization [34]. A deuterium incorporation NMR study supported by quantum chemical calculations showed that the intermediate of taxifolin with an open benzopyranone ring (α-hydroxychalcone related to IIc in our study) is very short-lived and the energy barrier for its formation is
PDF
Album
Supp Info
Full Research Paper
Published 08 May 2014

Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism

  • Denisa Tarabová,
  • Stanislava Šoralová,
  • Martin Breza,
  • Marek Fronc,
  • Wolfgang Holzer and
  • Viktor Milata

Beilstein J. Org. Chem. 2014, 10, 752–760, doi:10.3762/bjoc.10.70

Graphical Abstract
  • ). Quantum-chemical calculations To support the experimental results were also performed DFT (Density Functional Theory method) calculations by using the B3LYP hybrid functional [31][32][33] and 6-311++G** basis sets of the Gaussian basis set library [34]. The SCRF theory via the IEFPCM (Integral Equation
  • unsymmetrical structures of the ethylene substituent. This structure has been established by X-ray analysis. The tautomeric behavior of these materials has been modelled by using DFT quantum-chemical calculations. The most stable structural forms are 5aA1, 5aA2, 5bE1, 5bE2, 5cE1, 5cE2, 5dA1 and 5dA2. As
PDF
Album
Supp Info
Full Research Paper
Published 01 Apr 2014
Other Beilstein-Institut Open Science Activities