Conformational stability, molecular structure, intramolecular hydrogen bonding, and vibrational spectra of 5,5-dimethylhexane-2,4-dione

2011 ◽  
Vol 998 (1-3) ◽  
pp. 99-109 ◽  
Author(s):  
M. Vakili ◽  
S.F. Tayyari ◽  
A. Kanaani ◽  
A.-R. Nekoei ◽  
S. Salemi ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonding ◽  
Vibrational Spectra ◽  
Conformational Stability ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

Molecular and crystal structure of azadirachtin-H

1996 ◽  
Vol 52 (1) ◽  
pp. 145-150 ◽  
Author(s):  
T. R. Govindachari ◽  
Geetha Gopalakrishnan ◽  
S. S. Rajan ◽  
V. Kabaleeswaran ◽  
L. Lessinger
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Hydroxyl Group ◽  
Inhibiting Activity ◽  
Nmr Studies ◽  
Rotation Axes ◽  
Intramolecular Hydrogen ◽  
Azadirachtin A

Azadirachtin-H, isolated from the seed kernels of Azadirachta indica (neem), crystallizes in space group I4, Z = 8, with disordered ethyl acetate solvent filling channels along the fourfold rotation axes. The crystal structure determination showed that the previously reported molecular structure deduced from NMR studies was correct except for the stereochemistry at C(11). Azadirachtin-H, which belongs to a group of C-seco-tetranortriterpenoids (C-seco-limonoids) of great interest for their insect antifeedant and ecdysis-inhibiting activity, has some unusual features: the absence of a carbomethoxy group at C(11); the presence of a cyclic hemiacetal function at C(11); the α-orientation of the hydroxyl group on C(11), opposite to that in all other known azadirachtins with a hydroxyl group on C(11), except azadirachtin-I. There is no intramolecular hydrogen bonding. In this crystal the rotation of the two major moieties of the azadirachtin-H molecule about the single connecting C(8)—C(14) bond is quite different from that in azadirachtin-A, whose crystal structure has recently been determined.

Molecular Structure and Photoinduced Intramolecular Hydrogen Bonding in 2-Pyrrolylmethylidene Cycloalkanones

2015 ◽  
Vol 80 (21) ◽  
pp. 10521-10535 ◽  
Author(s):  
Mark Sigalov ◽  
Bagrat Shainyan ◽  
Nina Chipanina ◽  
Larisa Oznobikhina ◽  
Natalia Strashnikova ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

scholarly journals Intramolecular hydrogen bonding and conformational preferences on 2-fluoro-phenylaminocyclohexanol

2018 ◽  
Author(s):  
Cassia Chiari ◽  
Claudio Francisco Tormena ◽  
Kahlil Schwanka Salome ◽  
Laiza Bruzadelle Loureiro ◽  
Renan Vidal Viesser
Keyword(s):  
Hydrogen Bonding ◽  
Driving Force ◽  
Conformational Stability ◽  
Intramolecular Hydrogen Bonding ◽  
Quantum Mechanical ◽  
Resonance Spectroscopy ◽  
Quantum Mechanical Calculations ◽  
Conformational Preferences ◽  
Intramolecular Hydrogen ◽  
Theoretical Results

The aim of this study is to evaluate the influence and strength of possible intramolecular hydrogen bonding (IntraHB) involving N-H--O, O-H--N, O-H--F and N-H--F molecular moieties as a driving force on the conformational preferences of 2-fluoro-phenylaminocyclohexanol. To achieve our purpose we synthesized the compound and performed it's characterization using Nuclear Magnetic Resonance Spectroscopy (NMR). Quantum mechanical calculations were carried out to evaluate the effect of IntraHB on the conformational stability. Experimental and theoretical results showed that N-H--F and O-H--N IntraHB have a greater influence on the conformacional preferably adopted by the molecule.

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