Synthesis, isolation and characterization of a stable lithium stannenolate. A keto or an enol tautomer?

2021 ◽  
Vol 50 (39) ◽  
pp. 13651-13655
Author(s):  
Roman Bashkurov ◽  
Natalia Fridman ◽  
Dmitry Bravo-Zhivotovskii ◽  
Yitzhak Apeloig
Keyword(s):  
Spectroscopic Data ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Isolation And Characterization ◽  
Enol Tautomer

The synthesis and isolation of the first stable lithium stannenolate is reported. Structural and spectroscopic data, in combination with DFT quantum-mechanical calculations, indicate that the stannenolate adopts the keto tautomeric structure.

N2 positively charged defects in diamond. A quantum mechanical investigation of the structural, electronic, EPR and vibrational properties

2020 ◽  
Vol 8 (15) ◽  
pp. 5239-5247 ◽  
Author(s):  
Giulio Di Palma ◽  
Francesco Silvio Gentile ◽  
Valentina Lacivita ◽  
William C. Mackrodt ◽  
Mauro Causà ◽  
...  
Keyword(s):  
Ab Initio ◽  
Quantum Mechanical ◽  
Vibrational Properties ◽  
Quantum Mechanical Calculations ◽  
Mechanical Investigation ◽  
Crystal Code ◽  
Charged Defects ◽  
Positively Charged ◽  
Vibrational Characterization

Structural, EPR and vibrational characterization of the N2, N+2 and N++2 defects in diamond from ab initio quantum-mechanical calculations with the CRYSTAL code.

scholarly journals Isolation and Characterization of Crotosparsamide, a New Cyclic Nonapeptide from Croton sparsiflorus

2010 ◽  
Vol 5 (12) ◽  
pp. 1934578X1000501 ◽  
Author(s):  
Rashad Mehmood ◽  
Abdul Malik
Keyword(s):  
Spectroscopic Data ◽  
2D Nmr ◽  
Spectral Studies ◽  
Isolation And Characterization ◽  
First Time

Crotosparsamide (1), a new cyclic nonapeptide, has been isolated from the n-butanol soluble sub-fraction of Croton sparsiflorus along with p-hydroxy methylcinnamate and kaempferol, which are reported for the first time from this species. Their structures were determined by chemical and spectral studies including ESIMS, and 1D and 2D NMR spectroscopic data.

scholarly journals Three New Spongian Diterpenes from the Fijian Marine Sponge Spongia sp

2009 ◽  
Vol 4 (3) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Harald Gross ◽  
Anthony D. Wright ◽  
Uwe Reinscheid ◽  
Gabriele M. König
Keyword(s):  
Molecular Modeling ◽  
Marine Sponge ◽  
Spectroscopic Data ◽  
Chemical Investigation ◽  
Complete Analysis ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Fiji Islands ◽  
Combined Strategy ◽  
Spongian Diterpene

Chemical investigation of the marine sponge Spongia sp., collected from the Fiji Islands resulted in the isolation of three new furanoditerpenoids 1-3, along with the known compounds epispongiatriol (4) and 17,19-dihydroxyspongia-13(16),14-dien-2,3-dione (5) While 1 is a new spongian diterpene with a modified oxidation pattern, compounds 2 and 3 represent two new ring A-contracted spongians, displaying a novel and unprecedented nor-spongian carbon skeleton. Despite their labile nature the structures could be established through a combined strategy including complete analysis of spectroscopic data (NMR, MS), molecular modeling and quantum-mechanical calculations.

Vibration Frequencies and Normal Coordinates of Benzo(c)phenanthrene

2001 ◽  
Vol 56 (6-7) ◽  
pp. 499-504
Author(s):  
Rehab M. Kubba ◽  
Muthana Shanshal
Keyword(s):  
Spectroscopic Data ◽  
Normal Coordinate Analysis ◽  
Quantum Mechanical ◽  
Ir Absorption ◽  
Quantum Mechanical Calculations ◽  
Vibration Frequencies ◽  
Normal Coordinate ◽  
Normal Coordinates ◽  
Comparative Relations

Abstract MINDO/3-FORCES quantum mechanical calculations yielded non-planar (C2) geometry of Ben-zo(c)phenanthrene. The result agrees with the majority of published results but disagrees with others in which a planar (C2 V) structure was accepted in order to simplify the analysis of certain spectroscopic data. Vibration frequencies and IR absorption intensities were calculated then, applying the non-planar (C2) structure. A complete normal coordinate analysis for the molecule is reported. Inspection of these coordinates allowed the discovery of some useful comparative relations between them, which are re­ ported in the paper.

scholarly journals Isolation and characterization of Stigmasta-7, 22-dien-3-ol (α-Spinasterol) from Entada africana stem bark crude extract

2019 ◽  
Vol 4 (3) ◽  
pp. 85
Author(s):  
A. Kwajia ◽  
H.M. Adamub ◽  
I.Y. Chindob
Keyword(s):  
Crude Extract ◽  
Spectroscopic Data ◽  
Soluble Fraction ◽  
Stem Bark ◽  
Literature Analysis ◽  
Bark Sample ◽  
Isolation And Characterization ◽  
Nmr Data ◽  
Phytochemical Investigation

The phytochemical  investigation of the stem bark extracts of Entada africana led to the isolation and characterization of Stigmasta-7,22-dien-3-ol from the dichloromethane soluble portion of acetone/methanol (1:1v/v) crude extract. The powdered stem bark sample of Entada africana was defatted with hexane and extracted with acetone/methanol (1:1v/v) mixture. The dichloromethane soluble fraction was purified on a low pressure column containing silica gel 60 (60-200 mesh). The purification afforded an isolate coded Enac3 (85 mg) with Rf value of 0.404 in hexane/ethyl acetate (4:1). The isolate was characterized using IR, NMR data and in comparison with literature. Analysis of spectroscopic data and literature comparison suggests Enac3 as stigmasta-7, 22-dien-3-ol. The isolation of stigmasta-7, 22-dien-3-ol from the stem bark of Entada africana suggests the presence of useful bioactive principles which could be exploited for medicinal purposes.

Structure and Function of NzeB, a Versatile C–C and C–N Bond Forming Diketopiperazine Dimerase

2020 ◽  
Author(s):  
Vikram V. Shende ◽  
Yogan Khatri ◽  
Sean A. Newmister ◽  
Jacob N. Sanders ◽  
Petra Lindovska ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cytochrome P450 ◽  
Active Site ◽  
Structure And Function ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Bond Forming ◽  
And Function ◽  
Insight Into

This report details the discovery and characterization of a versatile bacterial cytochrome P450, NzeB, which catalyzes the dimerization of diketopiperazines via enzymatic C–H functionalization. This includes the first high-resolution crystal structure of a diketopiperazine dimerase, which along with active site via mutagenesis and quantum mechanical calculations, provides insight into the selectivity and mechanism of these enzymes.

scholarly journals Structure and Function of NzeB, a Versatile C–C and C–N Bond Forming Diketopiperazine Dimerase

2020 ◽  
Author(s):  
Vikram V. Shende ◽  
Yogan Khatri ◽  
Sean A. Newmister ◽  
Jacob N. Sanders ◽  
Petra Lindovska ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cytochrome P450 ◽  
Active Site ◽  
Structure And Function ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Bond Forming ◽  
And Function ◽  
Insight Into

This report details the discovery and characterization of a versatile bacterial cytochrome P450, NzeB, which catalyzes the dimerization of diketopiperazines via enzymatic C–H functionalization. This includes the first high-resolution crystal structure of a diketopiperazine dimerase, which along with active site via mutagenesis and quantum mechanical calculations, provides insight into the selectivity and mechanism of these enzymes.

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