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Journal articles on the topic 'Electronic circular dichroism (ECD)'

Author: Grafiati

Published: 24 April 2022

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1

Prabodh, Amrutha, Yichuan Wang, Stephan Sinn, et al. "Fluorescence detected circular dichroism (FDCD) for supramolecular host–guest complexes." Chemical Science 12, no. 27 (2021): 9420–31. http://dx.doi.org/10.1039/d1sc01411k.

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Fluorescence-detected circular dichroism (FDCD) spectroscopy is applied for the first time to supramolecular host–guest and host–protein systems and compared to the more known electronic circular dichroism (ECD).

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2

Górecki, Marcin. "A configurational and conformational study of (−)-Oseltamivir using a multi-chiroptical approach." Organic & Biomolecular Chemistry 13, no. 10 (2015): 2999–3010. http://dx.doi.org/10.1039/c4ob02369b.

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Four chiroptical methods, i.e. electronic circular dichroism (ECD), optical rotatory dispersion (ORD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) were employed to discover a set of the most probable conformations of (−)-Oseltamivir in solution.

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3

Halat, Monika, Magdalena Klimek-Chodacka, Jagoda Orleanska, Malgorzata Baranska, and Rafal Baranski. "Electronic Circular Dichroism of the Cas9 Protein and gRNA:Cas9 Ribonucleoprotein Complex." International Journal of Molecular Sciences 22, no. 6 (2021): 2937. http://dx.doi.org/10.3390/ijms22062937.

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The Streptococcus pyogenes Cas9 protein (SpCas9), a component of CRISPR-based immune system in microbes, has become commonly utilized for genome editing. This nuclease forms a ribonucleoprotein (RNP) complex with guide RNA (gRNA) which induces Cas9 structural changes and triggers its cleavage activity. Here, electronic circular dichroism (ECD) spectroscopy was used to confirm the RNP formation and to determine its individual components. The ECD spectra had characteristic features differentiating Cas9 and gRNA, the former showed a negative/positive profile with maxima located at 221, 209 and 19

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4

Muñoz, Marcelo A., María A. Bucio, and Pedro Joseph-Nathan. "Chiroptical Studies of Flavanone." Natural Product Communications 8, no. 8 (2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800810.

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Chiral HPLC coupled to electronic circular dichroism and laser optical rotation detection (HPLC-ECD-OR) permitted the on-line chiroptical characterization of both enantiomers of racemic flavanone (1) as ECD(-)310-OR(-)670-flavanone and ECD(+)310-OR(+)670-flavanone for the first and second eluted peaks, respectively. Calculation of the ECD spectrum of one enantiomer at the TD-DFT/DGTZVP level of theory yielded the ( S)-ECD(-)310-OR(-)670 and ( R)-ECD(+)310-OR(+)670-1 absolute configuration, in agreement with the use of empirical rules for stereochemical assignment. Vibrational circular dichrois

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5

Pescitelli, Gennaro, Lorenzo Di Bari, and Nina Berova. "Application of electronic circular dichroism in the study of supramolecular systems." Chem. Soc. Rev. 43, no. 15 (2014): 5211–33. http://dx.doi.org/10.1039/c4cs00104d.

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Electronic circular dichroism (ECD) is a choice technique for the analysis of chiral supramolecular systems, including their detection, determination of thermodynamic and kinetic quantities, and structural elucidation.

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6

Santoro, Ernesto, Giuseppe Mazzeo, Giulia Marsico, et al. "Assignment Through Chiroptical Methods of The Absolute Configuration of Fungal Dihydropyranpyran-4-5-Diones Phytotoxins, Potential Herbicides for Buffelgrass (Cenchrus ciliaris) Biocontrol." Molecules 24, no. 17 (2019): 3022. http://dx.doi.org/10.3390/molecules24173022.

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Radicinin and cochliotoxin (1 and 2) two phytotoxic pyranpyran-4,5-diones were isolated together with their close metabolites 3-epi-radicinin, radicinol, and its 3-epimer (3–5), from the culture filtrates of Cochliobolus australiensis, a fungus proposed as mycoherbcide for biocontrol of buffelgrass, a very noxious and dangerous weed. The absolute configuration of cochliotoxin was determined by chiroptical Optical Rotatory Dispersion (ORD), Electronic Circular Dichroism (ECD), and Vibrational Circular Dichroism (VCD)) and computational methods. The same methods were used to confirm that of radi

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7

Szymański, Marek P., Marcin Grajda, and Agnieszka Szumna. "Amplification of Electronic Circular Dichroism—A Tool to Follow Self-Assembly of Chiral Molecular Capsules." Molecules 26, no. 23 (2021): 7100. http://dx.doi.org/10.3390/molecules26237100.

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Electronic circular dichroism (ECD) can be used to study various aspects of self-assembly (definition of stoichiometric ratios, chirality amplification during self-assembly, host-guest complexation). In this work, we show that ECD is a valuable tool for monitoring the self-assembly of chiral peptide-based capsules. By analyzing the signs, intensities, and temperature dependences of ECD bands, the effects of the non-specific processes can be separated from the restriction of intramolecular motion (RIM) caused by discrete self-assembly. Analysis of experimental and theoretical ECD spectra show t

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8

McCann, Jennifer, Arvi Rauk, Gennadii V. Shustov, Hal Wieser та Danya Yang. "Electronic and Vibrational Circular Dichroism of Model β-Lactams: 3-Methyl- and 4-Methylazetidin-2-one". Applied Spectroscopy 50, № 5 (1996): 630–41. http://dx.doi.org/10.1366/0003702963905899.

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The chiroptical properties of the simplest chiral β-lactams, 3- and 4-methylazetidin-2-one, 1 and 2, respectively, were investigated. The experimental vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra were measured and compared with ab initio predictions. Both compounds were found to form dimers with calculated binding enthalpies and free energies of about −51 kJ/mol and −6 to −8 kJ/mol, respectively. The experimentally measured IR and VCD spectra were measured in concentrated nonpolar (CCl4) solution and are in agreement with the predicted IR and VCD spectra

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9

Lin, Jie, Renlei Wang, Guohua Xu, et al. "New cadinane sesquiterpenoids from the basidiomycetous fungus Pholiota sp." RSC Advances 6, no. 113 (2016): 112527–33. http://dx.doi.org/10.1039/c6ra22448b.

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The basidiomycetous fungus Pholiota sp. produced five new cadinane sesquiterpenoids pholiotins A–E (1–5). The absolute configurations were determined by X-ray diffraction, the Snatzke's method and electronic circular dichroism (ECD) calculations.

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10

Padula, Daniele, Fabrizio Santoro, and Gennaro Pescitelli. "A simple dimeric model accounts for the vibronic ECD spectra of chiral polythiophenes in their aggregated states." RSC Advances 6, no. 44 (2016): 37938–43. http://dx.doi.org/10.1039/c6ra05500a.

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Aggregates of chiral polythiophenes (PTs) show exciton-coupled electronic circular dichroism (ECD) spectra with a unique vibronic structure, which can be reproduced by quantum dynamical simulations on the coupled states of small dimeric models.

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11

Bai, Meng, Guo-Lei Huang, Rong-Qing Mei, et al. "Bioactive Lactones from the Mangrove-Derived Fungus Penicillium sp. TGM112." Marine Drugs 17, no. 8 (2019): 433. http://dx.doi.org/10.3390/md17080433.

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Three new lactones penicilactones A−C (1−3) were obtained from the mangrove-derived fungus Penicillium sp. TGM112. Their structures and absolute configurations were determined by detailed NMR, MS spectroscopic data, Mo2(OAc)4-induced electronic circular dichroism (ECD), and circular dichroism (CD) spectroscopy. Compound 1 showed antibacterial activity against Staphylococcus aureus with an MIC value of 6.25 μg/mL. Compound 2 showed insecticidal activity against newly hatched larvae of Culex quinquefasciatus with the LC50 value of 78.5 (±0.58) μg/mL.

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12

Górecki, Marcin, Valerio Zullo, Anna Iuliano, and Gennaro Pescitelli. "On the Absolute Stereochemistry of Tolterodine: A Circular Dichroism Study." Pharmaceuticals 12, no. 1 (2019): 21. http://dx.doi.org/10.3390/ph12010021.

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Tolterodine (1) is a potent muscarinic receptor antagonist used in the treatment of overactive urinary bladder (OAB) syndrome. Tolterodine is chiral and it was patented, and is currently marketed, as the l-tartrate salt of the (R)-enantiomer. However, the existing literature does not offer an ultimate proof of a stereoselective mode of action of 1. A second open stereochemical issue concerns the absolute configuration (AC) of 1. Neither the original patents nor subsequent studies have established the AC of 1 in an unambiguous way, although the AC of the l-tartrate salt of 1 was assigned by X-r

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13

Norman, Patrick, Joseph Parello, Prasad L. Polavarapu, and Mathieu Linares. "Predicting near-UV electronic circular dichroism in nucleosomal DNA by means of DFT response theory." Physical Chemistry Chemical Physics 17, no. 34 (2015): 21866–79. http://dx.doi.org/10.1039/c5cp02481a.

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It is demonstrated that time-dependent density functional theory (DFT) calculations can accurately predict changes in near-UV electronic circular dichroism (ECD) spectra of DNA as the structure is altered from the linear (free) B-DNA form to the supercoiled N-DNA form found in nucleosome core particles.

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14

Niemeyer, Niklas, Marco Caricato, and Johannes Neugebauer. "Origin invariant electronic circular dichroism in the length dipole gauge without London atomic orbitals." Journal of Chemical Physics 156, no. 15 (2022): 154114. http://dx.doi.org/10.1063/5.0088922.

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We present a method for obtaining origin-independent electronic circular dichroism (ECD) in the length-gauge representation LG(OI) without the usage of London atomic orbitals. This approach builds upon the work by Caricato [J. Chem. Phys. 153, 151101 (2020)] and is applied to rotatory strengths and ECD spectra from damped response theory. Numerical results are presented for time-dependent Hartree–Fock and density-functional theory, the second-order algebraic diagrammatic construction method, and linear-response coupled-cluster theory with singles and approximate doubles. We can support the fin

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15

de Moura, Patrícia Homobono Brito, Wolfgang Brandt, Andrea Porzel, Roberto Carlos Campos Martins, Ivana Correa Ramos Leal та Ludger A. Wessjohann. "Structural Elucidation of an Atropisomeric Entcassiflavan-(4β→8)-Epicatechin Isolated from Dalbergia monetaria L.f. Based on NMR and ECD Calculations in Comparison to Experimental Data". Molecules 27, № 8 (2022): 2512. http://dx.doi.org/10.3390/molecules27082512.

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A rare dihydoxyflavan-epicatechin proanthocyanidin, entcassiflavan-(4β→8)-epicatechin, was isolated from Dalbergia monetaria, a plant widely used by traditional people from the Amazon to treat urinary tract infections. The constitution and relative configuration of the compound were elucidated by HR-MS and detailed 1D- and 2D-NMR measurements. By comparing the experimental electronic circular dichroism (ECD) spectrum with the calculated ECD spectra of all 16 possible isomers, the absolute configuration, the interflavan linkage, and the atropisomers could be determined.

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16

Evans, Amanda C., Andrew S. Petit, Steven G. Guillen, Amanda J. Neukirch, Søren V. Hoffmann, and Nykola C. Jones. "Chiroptical characterization tools for asymmetric small molecules – experimental and computational approaches for electronic circular dichroism (ECD) and anisotropy spectroscopy." RSC Advances 11, no. 3 (2021): 1635–43. http://dx.doi.org/10.1039/d0ra06832b.

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Experimental and computational electronic circular dichroism spectra are used in conjunction with anisotropy spectra to chiroptically characterize mandelic acid and its derivatives into the vacuum UV.

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17

Okuom, Macduff O., Raychelle Burks, Crysta Naylor, and Andrea E. Holmes. "Applied Circular Dichroism: A Facile Spectroscopic Tool for Configurational Assignment and Determination of Enantiopurity." Journal of Analytical Methods in Chemistry 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/865605.

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In order to determine if electronic circular dichroism (ECD) is a good tool for the qualitative evaluation of absolute configuration and enantiopurity in the absence of chiral high performance liquid chromatography (HPLC), ECD studies were performed on several prescriptions and over-the-counter drugs. Cotton effects (CE) were observed for both S and R isomers between 200 and 300 nm. For the drugs examined in this study, the S isomers showed a negative CE, while the R isomers displayed a positive CE. The ECD spectra of both enantiomers were nearly mirror images, with the amplitude proportional

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18

Marsico, Giulia, Umberto Calice, Patrizia Scafato, Sandra Belviso, Antonio Evidente, and Stefano Superchi. "Computational Approaches and Use of Chiroptical Probes in the Absolute Configuration Assignment to Natural Products by ECD Spectroscopy: A 1,2,3-Trihydroxy-p-menthane as a Case Study." Biomolecules 12, no. 3 (2022): 421. http://dx.doi.org/10.3390/biom12030421.

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In this study, the computational analysis of electronic circular dichroism (ECD) spectra and the employment of biphenyl chiroptical probes were compared in the absolute configuration assignment of (-)-1α,2α,3β-trihydroxy-p-menthane (1), taken as a representative example of a UV-transparent chiral natural product. The usefulness of chiroptical probes in the configurational assignments of natural products and their complementarity to the computational protocols is herein highlighted. The biphenyl probe approach proves to be straightforward, reliable, and suitable for conformationally mobile and

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19

Xing, Cui-Ping, Chun-Lan Xie, Jin-Mei Xia, et al. "Penigrisacids A–D, Four New Sesquiterpenes from the Deep-Sea-Derived Penicillium griseofulvum." Marine Drugs 17, no. 9 (2019): 507. http://dx.doi.org/10.3390/md17090507.

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Four new (penigrisacids A–D, 1–4) and one known (5) carotane sesquiterpenoids were isolated from the deep-sea-derived fungus Penicillium griseofulvum, along with four known compounds (6–9). The planar structures and relative configurations of the new compounds were determined by extensive analysis of the NMR and HRESIMS data. The absolute configurations were established by comparison of the experimental and calculated ECD (electronic circular dichroism) spectra or OR (optical rotation) value. Compound 9 exhibited potent anti-food allergic activity with IC50 value of 28.7 μM, while 4 showed wea

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20

Zanchi, Chiara, Giovanna Longhi, Sergio Abbate, Giovanni Pellegrini, Paolo Biagioni, and Matteo Tommasini. "Evaluation of Molecular Polarizability and of Intensity Carrying Modes Contributions in Circular Dichroism Spectroscopies." Applied Sciences 9, no. 21 (2019): 4691. http://dx.doi.org/10.3390/app9214691.

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We re-examine the theory of electronic and vibrational circular dichroism spectroscopy in terms of the formalism of frequency-dependent molecular polarizabilities. We show the link between Fermi’s gold rule in circular dichroism and the trace of the complex electric dipole–magnetic dipole polarizability. We introduce the C++ code polar to compute the molecular polarizability complex tensors from quantum chemistry outputs, thus simulating straightforwardly UV-visible absorption (UV-Vis)/electronic circular dichroism (ECD) spectra, and infrared (IR)/vibrational circular dichroism (VCD) spectra.

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21

Li, Jing, Yi-sheng Zhong, Jie Yuan, et al. "A New Terminal Cyano Group-containing Benzodiazepine Alkaloid from the Mangrove Endophytic Fungus Penicillium sp." Natural Product Communications 10, no. 9 (2015): 1934578X1501000. http://dx.doi.org/10.1177/1934578x1501000916.

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A new benzodiazepine alkaloid containing terminal cyano group has been isolated from a mangrove endophytic fungus, Penicillium 299#. Structure elucidation was determined by 1D and 2D NMR spectroscopy and the absolute configuration was determined by electronic circular dichroism (ECD). The new compound showed no cytotoxic activities in vitro against human cancer lines MDA-MB-435, HepG2, HCT-116, and Calu-3.

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22

Yuan, Wen-Juan, Wen-Fen Gao, Jia-Hui Zhang, et al. "(±)-Perforison A, A Pair of New Chromone Enantiomers from Harrisonia perforata." Natural Product Communications 12, no. 1 (2017): 1934578X1701200. http://dx.doi.org/10.1177/1934578x1701200118.

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(+)-Perforison A and (-)-perforison A, a new pair of chromone enantiomers, along with four known compounds, were isolated from the leaves and stems of Harrisonia perforata. Their structures and absolute configurations were determined on the basis of extensive analysis of spectroscopic data and electronic circular dichroism (ECD) calculations. The cytotoxic activities in vitro of these compounds were evaluated, but none showed significant activity.

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23

Superchi, Stefano, Patrizia Scafato, Marcin Gorecki, and Gennaro Pescitelli. "Absolute Configuration Determination by Quantum Mechanical Calculation of Chiroptical Spectra: Basics and Applications to Fungal Metabolites." Current Medicinal Chemistry 25, no. 2 (2018): 287–320. http://dx.doi.org/10.2174/0929867324666170310112009.

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Background: Quantum mechanical simulations of chiroptical properties, such as electronic circular dichroism (ECD), optical rotation (OR), and vibrational circular dichroism (VCD), have rapidly become very popular to assign the absolute configuration of novel natural products. Objective: We review the application of the ECD/OR/VCD computational methodology to chiral metabolites of fungal origin. First, we summarize the fundamentals of the three spectroscopies; then, we focus on the specific experimental and computational issues allied to the application of their calculations. Methods: We survey

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24

Polyanichko, Alexander, and Helmut Wieser. "Structural organization of DNA–protein complexes of chromatin studied by vibrational and electronic circular dichroism." Spectroscopy 24, no. 3-4 (2010): 239–44. http://dx.doi.org/10.1155/2010/658374.

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Structure and functioning of chromatin is determined by interactions of DNA with numerous nuclear proteins. The most abundant and yet not completely understood non-histone chromosomal proteins are those belonging to a High Mobility Group (HMG) namely HMGB1. The interplay of this protein on DNA with linker histone H1 and other proteins determines both structure and functioning of the chromatin. A combination of UV and IR absorption and circular dichroism (CD) spectroscopy was applied to investigate the structure and formation of large supramolecular DNA–protein complexes. This combination of te

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25

Hu, Yalin, Li Heng, Rong Xu, et al. "Meliacarpinin-Type Limonoids from the Bark of Melia toosendan." Molecules 23, no. 10 (2018): 2590. http://dx.doi.org/10.3390/molecules23102590.

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Three new meliacarpinin-type limonoids, toosendanes A–C (1–3), along with three, known meliacarpinins (4–6) were isolated from the bark of Melia toosendan. Their structures, along with their absolute configurations, were elucidated, based on detailed analyses. These included HRESIMS and 1D/2D-NMR, modified Mosher’s method, and electronic circular dichroism (ECD). Limonoids 2 and 3 showed moderate inhibitory activity on LPS-activated, RAW 264.7 macrophages.

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26

Dai, Yu, Kunlong Li, Jianglian She, et al. "Lipopeptide Epimers and a Phthalide Glycerol Ether with AChE Inhibitory Activities from the Marine-Derived Fungus Cochliobolus Lunatus SCSIO41401." Marine Drugs 18, no. 11 (2020): 547. http://dx.doi.org/10.3390/md18110547.

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A pair of novel lipopeptide epimers, sinulariapeptides A (1) and B (2), and a new phthalide glycerol ether (3) were isolated from the marine algal-associated fungus Cochliobolus lunatus SCSIO41401, together with three known chromanone derivates (4–6). The structures of the new compounds, including the absolute configurations, were determined by comprehensive spectroscopic methods, experimental and calculated electronic circular dichroism (ECD), and Mo2 (OAc)4-induced ECD methods. The new compounds 1–3 showed moderate inhibitory activity against acetylcholinesterase (AChE), with IC50 values of

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27

Mazzeo, Giuseppe, Sergio Abbate, Stefan E. Boiadjiev, David A. Lightner, and Giovanna Longhi. "Vibrational Circular Dichroism Detects Symmetry Breaking due to Conformational Mobility in C2-Symmetry Chiral Molecules and Provides Further Insight into Inter-Chromophoric Interactions." Symmetry 12, no. 11 (2020): 1752. http://dx.doi.org/10.3390/sym12111752.

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Bicyclo[3.3.1]nonane-2,6-dione (1) and bicyclo[3.3.1]nona-3,7-diene-2,6-dione (2) have been examined by vibrational circular dichroism (VCD), which, as for most C2-symmetric systems, exhibits strong VCD signals. In the case of 2, VCD signals are stronger and sharper with several bisignate doublets; for 1, signals are less intense and broader. The VCD and IR spectra are excellently predicted by DFT calculations: only one conformer is present for 2, while for 1, three main conformers, related through concerted skeleton torsional motions are present (two of them being interchanged by C2-rotation)

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28

Lee, Jin Su, Miran Jeong, Sangsu Park, et al. "Chemical Constituents of the Leaves of Butterbur (Petasites japonicus) and Their Anti-Inflammatory Effects." Biomolecules 9, no. 12 (2019): 806. http://dx.doi.org/10.3390/biom9120806.

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Two new aryltetralin lactone lignans, petasitesins A and B were isolated from the hot water extract of the leaves of butterbur (Petasites japonicus) along with six known compounds. The chemical structures of lignans 1 and 2 were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data, electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectra. Petasitesin A and cimicifugic acid D showed significant inhibitory effects on the production of both prostaglandin E2 (PGE2) and NO in RAW264.7 macrophages. The expressions of inducible nitric ox

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29

Karabencheva-Christova, Tatyana G., Warispreet Singh, and Christo Z. Christov. "Computational Study of the Structure, the Flexibility, and the Electronic Circular Dichroism of Staurosporine – a Powerful Protein Kinase Inhibitor." Zeitschrift für Naturforschung A 69, no. 7 (2014): 331–38. http://dx.doi.org/10.5560/zna.2014-0021.

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Staurosporine (STU) is a microbial alkaloid which is an universal kinase inhibitor. In order to understand its mechanism of action it is important to explore its structure-properties relationships. In this paper we provide the results of a computational study of the structure, the chiroptical properties, the conformational flexibility of STU as well as the correlation between the electronic circular dichroism (ECD) spectra and the structure of its complex with anaplastic lymphoma kinase.

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30

Tang, Yu, Juan Xiong, and Jin-Feng Hu. "Lycopodium Alkaloids from Diphasiastrum complanatum." Natural Product Communications 10, no. 12 (2015): 1934578X1501001. http://dx.doi.org/10.1177/1934578x1501001219.

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One new lycopodine-type Lycopodium alkaloid, dehydroisofawcettiine N-oxide (1) and eleven known analogues (2–12) were isolated from the whole plant of Diphasiastrum complanatum. The new structure was established on the basis of spectroscopic methods, including 2D NMR techniques. The absolute configurations of 2 and its new N-oxide derivative (1) were deduced by chemical transformation combined with Cotton effects in their electronic circular dichroism (ECD) spectra.

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31

Li, Tian-Yi, You-Xuan Zheng, and Yong-Hui Zhou. "Iridium(iii) phosphorescent complexes with dual stereogenic centers: single crystal, electronic circular dichroism evidence and circularly polarized luminescence properties." Dalton Transactions 45, no. 48 (2016): 19234–37. http://dx.doi.org/10.1039/c6dt04030f.

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Two iridium complexes with a chiral metal center and chiral carbons were separated as four isomers termed Λ/Δ-(dfppy)<sub>2</sub>Ir(chty-R) and Λ/Δ-(dfppy)<sub>2</sub>Ir(chty-S). Each enantiomeric couple shows mirror-image crystal structures, and ECD/CPL spectra highlight both the chiral sources.

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32

Zhang, Dongdong, Yanhong Shi, Rui Xu, et al. "Alkaloid Enantiomers from the Roots of Isatis indigotica." Molecules 24, no. 17 (2019): 3140. http://dx.doi.org/10.3390/molecules24173140.

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Five pairs of alkaloid enantiomers (1a/1b–5a/5b) were obtained from Isatis indigotica (I. indigotica) roots. Among them, 1a/1b, 2a/2b and 3a/3b were determined as three pairs of new alkaloid enantiomers. Their structures were elucidated by physicochemical properties and spectroscopic methods. The absolute configurations were deduced by comparison of their experimental circular dichroism (CD) and calculated electronic circular dichroism (ECD) spectra, as well as by single-crystal X-ray crystallography using anomalous scattering of Cu Kα radiation. Alkaloids 1a and 1b possess an unpresented carb

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33

Walaszek, Dominika J., Magdalena Jawiczuk, Jakub Durka, Olga Drapała та Dorota Gryko. "α-Photooxygenation of chiral aldehydes with singlet oxygen". Beilstein Journal of Organic Chemistry 15 (30 серпня 2019): 2076–84. http://dx.doi.org/10.3762/bjoc.15.205.

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Organocatalytic α-oxygenation of chiral aldehydes with photochemically generated singlet oxygen allows synthesizing chiral 3-substituted 1,2-diols. Stereochemical results indicate that the reaction in the presence of diarylprolinol silyl ethers is highly diastereoselective and that the configuration of a newly created stereocenter at the α-position depends predominantly on the catalyst structure. The absolute configuration of chiral 1,2-diols has been unambiguously established based on electronic circular dichroism (ECD) and TD-DFT methods.

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34

Yang, Meng-Yue, Jian-Kun Yang, Jin-Kai Yang, Lian-Dong Hu, Hua-Jie Zhu, and Fei Cao. "New Oxygenated Steroid from the Marine-Derived Fungus Aspergillus flavus." Natural Product Communications 13, no. 8 (2018): 1934578X1801300. http://dx.doi.org/10.1177/1934578x1801300807.

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One new oxygenated steroid, named aspersteroid A (1), and three known analogues (2–4) were isolated from the marine-derived fungus Aspergillus flavus collected from the Bohai Sea. Their structures were elucidated by spectroscopic analyses and by comparison with previously reported data. The absolute configuration of tetracyclic nucleus in 1 was assigned by quantum chemical calculation of the electronic circular dichroism (ECD) spectrum. All the compounds were evaluated for their cytotoxic and antibacterial activities.

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35

Sato, Hisako, Fumi Sato, and Akihiko Yamagishi. "Chiral Tectonics: VCD and ECD Application for Epimerization of a Star-Burst Tetranuclear Complex with a Labile Central Core." Inorganics 6, no. 3 (2018): 70. http://dx.doi.org/10.3390/inorganics6030070.

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The present article reports the application of vibrational circular dichroism (VCD) and temperature-dependent electronic circular dichroism (ECD) methods to reveal the dynamical aspects of a star-burst tetranuclear metal complex with a labile central core in a solution. One-handed chiral inert tecton, ∆- or Λ-[Ru(III)(acac)2(taetH)] (acacH = acetylacetone, taetH2 = tetraacetylethane), was prepared by reacting [Ru(acac)3] with taetH2 in solid at 120 °C. The ∆Λ-pair of pure enantiomers was obtained chromatographically. On adding Al(ClO4)3 to its enantiopure solution, three units of one-handed te

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Asha, Haritha, James A. Green, Lara Martinez-Fernandez, Luciana Esposito, and Roberto Improta. "Electronic Circular Dichroism Spectra of DNA Quadruple Helices Studied by Molecular Dynamics Simulations and Excitonic Calculations including Charge Transfer States." Molecules 26, no. 16 (2021): 4789. http://dx.doi.org/10.3390/molecules26164789.

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We here investigate the Electronic Circular Dichroism (ECD) Spectra of two representative Guanine-rich sequences folded in a Quadruple helix (GQ), by using a recently developed fragment diabatisation based excitonic model (FrDEx). FrDEx can include charge transfer (CT) excited states and consider the effect of the surrounding monomers on the local excitations (LEs). When applied to different structures generated by molecular dynamics simulations on a fragment of the human telomeric sequence (Tel21/22), FrDEx provides spectra fully consistent with the experimental one and in good agreement with

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37

Feng, Guipeng, Guoyang Ma, Wenyan Chen, Shaohong Xu, Kaikai Wang, and Shaoyan Wang. "Asymmetric Synthesis of Tetrahydroisoquinoline Derivatives through 1,3-Dipolar Cycloaddition of C,N-Cyclic Azomethine Imines with Allyl Alkyl Ketones." Molecules 26, no. 10 (2021): 2969. http://dx.doi.org/10.3390/molecules26102969.

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A [3 + 2] 1,3-Dipolar cycloaddition of C,N-cyclic azomethine imines with allyl alkyl ketones has been achieved. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. An array of tetrahydroisoquinoline derivatives is generally constructed with good diastereoselectivities and enantioselectivities (up to >25:1 dr, >95% ee). Moreover, the absolute configuration of the product was previously determined by using the quantum electronic circular dichroism calculation and ECD spectrum method.

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Cheng, Zhongbin, Wei Xu, Lijun Liu, et al. "Peniginsengins B–E, New Farnesylcyclohexenones from the Deep Sea-Derived Fungus Penicillium sp. YPGA11." Marine Drugs 16, no. 10 (2018): 358. http://dx.doi.org/10.3390/md16100358.

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Chemical examination of the EtOAc extract of the deep sea-derived fungus Penicillium sp. YPGA11 resulted in the isolation of four new farnesylcyclohexenones, peniginsengins B–E (1–4), and a known analog peniginsengin A (5). The structures of compounds 1–4 were determined on the basis of comprehensive analyses of the nuclear magnetic resonance (NMR) and mass spectroscopy (MS) data, and the absolute configurations of 1, 2, and 4 were determined by comparisons of experimental electronic circular dichroism (ECD) with calculated ECD spectra. Compounds 1–5, characterized by a highly oxygenated 1-met

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Pearce, A., Brent Copp, and Tadeusz Molinski. "Enantiomeric Variability of Distaminolyne A. Refinement of ECD and NMR Methods for Determining Optical Purity of 1-Amino-2-Alkanols." Molecules 24, no. 1 (2018): 90. http://dx.doi.org/10.3390/molecules24010090.

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Sample configurations of distaminolyne A (1a); isolated from the ascidians Pseudodistoma opacum and P. cereum, and collected at different sites in New Zealand, were investigated by two methods: Exciton coupled electronic circular dichroism (EC ECD) of the corresponding N,O-dibenzoyl derivative 1b; and chiral reagent derivatization of 1a with (S)- and (R)-α-methoxyphenylacetic acid (MPA), followed by 1H-NMR analysis. Configuration and optical purity of 1a (%ee) was found to vary depending on the geographic distribution of ascidian colonies. An improved method for preparing N,O-diarenoyl derivat

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Abdel-Wahab, Nada, Sebastian Scharf, Ferhat Özkaya, et al. "Induction of Secondary Metabolites from the Marine-Derived Fungus Aspergillus versicolor through Co-cultivation with Bacillus subtilis." Planta Medica 85, no. 06 (2019): 503–12. http://dx.doi.org/10.1055/a-0835-2332.

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AbstractA new cyclic pentapeptide, cotteslosin C (1), a new aflaquinolone, 22-epi-aflaquinolone B (3), and two new anthraquinones (9 and 10), along with thirty known compounds (2, 4 – 8, 11 – 34) were isolated from a co-culture of the sponge-associated fungus Aspergillus versicolor with Bacillus subtilis. The new metabolites were only detected in the co-culture extract, but not when the fungus was grown under axenic conditions. Furthermore, the co-culture extract exhibited an enhanced accumulation of the known constituents versicolorin B (14), averufin (16), and sterigmatocyctin (19) by factor

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Xu, Mao, Xue, et al. "Structures and Absolute Configurations of Diketopiperazine Alkaloids Chrysopiperazines A–C from the Gorgonian-Derived Penicillium chrysogenum Fungus." Marine Drugs 17, no. 5 (2019): 250. http://dx.doi.org/10.3390/md17050250.

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Three new diketopiperazine alkaloids, including two oxepine‐containing diketopiperazines, chrysopiperazines A and B (1 and 2), and one quinazoline‐containing diketopiperazine, chrysopiperazine C (5), together with three known analogues (3, 4, and 6), were isolated from the gorgonian-derived Penicillium chrysogenum fungus. The relative and absolute configurations of C-3 and C-15 in 1 and 2, C-3 and C-14 in 5 were established by NOE modified Marfey’s analysis and electronic circular dichroism (ECD) calculations. Particularly, the absolute configurations of C-19 in 1 and 3, which was very challen

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Makkonen, Esko, Patrick Rinke, Olga Lopez-Acevedo, and Xi Chen. "Optical Properties of Silver-Mediated DNA from Molecular Dynamics and Time Dependent Density Functional Theory." International Journal of Molecular Sciences 19, no. 8 (2018): 2346. http://dx.doi.org/10.3390/ijms19082346.

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We report a combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics and time-dependent density functional (TDDFT) study of metal-mediated deoxyribonucleic acid (M-DNA) nanostructures. For the Ag + -mediated guanine tetramer, we found the maug-cc-pvdz basis set to be sufficient for calculating electronic circular dichroism (ECD) spectra. Our calculations further show that the B3LYP, CAM-B3LYP, B3LYP*, and PBE exchange-correlation functionals are all able to predict negative peaks in the measured ECD spectra within a 20 nm range. However, a spurious positive peak is present in

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Pancoska, Petr, Vit Janota, and Timothy A. Keiderling. "Interconvertibility of Electronic and Vibrational Circular Dichroism Spectra of Proteins: A Test of Principle Using Neural Network Mapping." Applied Spectroscopy 50, no. 5 (1996): 658–68. http://dx.doi.org/10.1366/0003702963905916.

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Electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) are compared with respect to their interconvertibility for protein structural studies. ECD and amide I' VCD spectra of 28 proteins were used with a backpropagation projection neural network with one hidden layer to develop a mapping between the two spectral types. After the network converged, the number of neurons in the hidden layer was optimized by principal component analysis of the synaptic weights of the pilot network topology with redundant hidden neurons. Actual prediction of one spectrum from the other for ind

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Xu, Dongbo, Erli Tian, Fandong Kong, and Kui Hong. "Bioactive Molecules from Mangrove Streptomyces qinglanensis 172205." Marine Drugs 18, no. 5 (2020): 255. http://dx.doi.org/10.3390/md18050255.

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Five new compounds 15R-17,18-dehydroxantholipin (1), (3E,5E,7E)-3-methyldeca-3,5,7-triene-2,9-dione (2) and qinlactone A–C (3–5) were identified from mangrove Streptomyces qinglanensis 172205 with “genetic dereplication,” which deleted the highly expressed secondary metabolite-enterocin biosynthetic gene cluster. The chemical structures were established by spectroscopic methods, and the absolute configurations were determined by electronic circular dichroism (ECD). Compound 1 exhibited strong anti-microbial and antiproliferative bioactivities, while compounds 2–4 showed weak antiproliferative

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Guo, Da-Le, Xiao-Hua Li, Dan Feng, et al. "Novel Polyketides Produced by the Endophytic Fungus Aspergillus Fumigatus from Cordyceps Sinensis." Molecules 23, no. 7 (2018): 1709. http://dx.doi.org/10.3390/molecules23071709.

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Five new polyketides, including two pairs of enantiomers and a racemate, were isolated from the fermentation broth of Aspergillus fumigatus, an endophytic fungus isolated from Cordyceps sinensis. Their structures were identified using one-dimensional (1D) and two-dimensional (2D) NMR experiments, and the absolute configurations of the enantiomers were confirmed using electronic circular dichroism (ECD) calculations. Compounds 1a and 2a exhibited inhibitory activity against the MV4-11 cell line in vitro, with IC50 values of 23.95 µM and 32.70 µM, respectively.

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Kawabe, Hiroshi, Riyo Suzuki, Hiroshi Hirota, Keiichi Matsuzaki, Xun Gong, and Ayumi Ohsaki. "A New Diterpenoid with a Rearranged Skeleton from Salvia prattii." Natural Product Communications 12, no. 8 (2017): 1934578X1701200. http://dx.doi.org/10.1177/1934578x1701200807.

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A new diterpenoid with a rearranged skeleton, prattinin A (1), was isolated along with five known compounds (2–6) from the roots of Salvia prattii. The structure of 1 bearing a methyl group at the C-5 position was established by extensive spectroscopic analyses and the absolute configuration of 1 was elucidated by comparing the calculated and experimental electronic circular dichroism (ECD) spectra. Compounds 1, 3, 4, and 5 exhibited moderate or weak cytotoxicity against HL-60 and HeLa cell lines.

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Li, Tantan, Yun Wang, Li Li, et al. "New Cytotoxic Cytochalasans from a Plant-Associated Fungus Chaetomium globosum kz-19." Marine Drugs 19, no. 8 (2021): 438. http://dx.doi.org/10.3390/md19080438.

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Four new cytochalasans, phychaetoglobins A–D (1–4), together with twelve known cytochalasans (5–16), were isolated from a mangrove-associated fungus Chaetomium globosum kz-19. The new structures were elucidated on the basis of extensive 1D and 2D NMR, HR ESIMS spectroscopic analyses, and electronic circular dichroism (ECD) calculations. The absolute configuration of 2 was established by application of Mosher’s method. Compounds 4–8 exhibited moderate cytotoxicities against A549 and HeLa cell lines with the IC50 values less than 20 μM.

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Guo, Yin, Zhang, et al. "Chaetomadrasins A and B, Two New Cytotoxic Cytochalasans from Desert Soil-Derived Fungus Chaetomium madrasense 375." Molecules 24, no. 18 (2019): 3240. http://dx.doi.org/10.3390/molecules24183240.

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Two new cytochalasans, Chaetomadrasins A (1) and B (2), along with six known analogues (3–8), were isolated from the solid-state fermented culture of desert soil-derived Chaetomium madrasense 375. Their structures were clarified by comprehensive spectroscopic analyses, and the absolute configurations of Compounds 1 and 2 were confirmed by electronic circular dichroism (ECD) and calculated ECD. For the first time, Chaetomadrasins A (1), which belongs to the chaetoglobosin family, is characterized by the presence of all oxygen atoms in the form of Carbonyl. Chaetomadrasin B (2) represents the fi

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Padula, Daniele, Javier Cerezo, Gennaro Pescitelli, and Fabrizio Santoro. "The shape of the electronic circular dichroism spectrum of (2,6-dimethylphenyl)(phenyl)methanol: interplay between conformational equilibria and vibronic effects." Physical Chemistry Chemical Physics 19, no. 48 (2017): 32349–60. http://dx.doi.org/10.1039/c7cp06369e.

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Domzalski, Alison, Liliana Margent, Valeria Vigo, et al. "Unambiguous Stereochemical Assignment of Cyclo(Phe-Pro), Cyclo(Leu-Pro), and Cyclo(Val-Pro) by Electronic Circular Dichroic Spectroscopy." Molecules 26, no. 19 (2021): 5981. http://dx.doi.org/10.3390/molecules26195981.

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2,5-diketopiperazines (DKPs) are cyclic dipeptides ubiquitously found in nature. In particular, cyclo(Phe-Pro), cyclo(Leu-Pro), and cyclo(Val-Pro) are frequently detected in many microbial cultures. Each of these DKPs has four possible stereoisomers due to the presence of two chirality centers. However, absolute configurations of natural DKPs are often ambiguous due to the lack of a simple, sensitive, and reproducible method for stereochemical assignment. This is an important problem because stereochemistry is a key determinant of biological activity. Here, we report a synthetic DKP library co

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