Topic
Conformational isomerism
About: Conformational isomerism is a research topic. Over the lifetime, 11563 publications have been published within this topic receiving 199312 citations.
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TL;DR: In this article, the crystal and molecular structure of two 3-(2-benzyloxy-6-hydroxyphenyl)-5-styryl pyrazoles were determined by X-ray analysis.
53 citations
TL;DR: The synthesis, characterization and fundamental of the dual excited-state proton-transfer properties of 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one (1a) are reported and the interplay between two HB conformers with on(1a(O))/off(1 a(N)) character in tautomer emission may find future applications such as the recognition of organic Lewis acid/base in organic solvents
Abstract: The synthesis, characterization and fundamental of the dual excited-state proton-transfer properties of 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one (1a) are reported. In the electronic ground state, there exist two competitive hydrogen bonding (HB) isomers for 1a. Conformer 1a(O) reveals a five-membered ring HB structure between O−H and carbonyl oxygen, while conformer 1a(N) possesses a six-membered ring HB formation between O−H and pyridyl nitrogen. In a single crystal, the X-ray crystallography unveils an exclusive formation of conformer 1a(N). In solution such as CH2Cl2, 1a(O) and 1a(N) are in equilibrium, and their respective absorption chromophores are significantly different due to different degrees of hydrogen-bond induced π electron delocalization. Upon excitation, both conformers 1a(O) and 1a(N) undergo excited-state intramolecular proton transfer (ESIPT) reaction. Following ESIPT, 1a(O) gives rise to a tautomer emission maximized at 534 nm in CH2Cl2. Conversely, due to dominant radiationless que...
53 citations
TL;DR: A three dimensional structure of the antamanide·Na+ complex has been proposed containing four intramolecular hydrogen bonds formed by the amide CO and NH groups, which explains the efficiency and selectivity of theantamanide complexation reaction.
53 citations
TL;DR: It is demonstrated that the VCD technique can be used as a powerful tool for structural investigation of intermolecular interactions of chiral molecules and can yield information complementary to data obtained through other molecular spectroscopy methods.
Abstract: This paper presents a discussion of the interaction energies, conformations, vibrational absorption (VA, harmonic and anharmonic) and vibrational circular dichroism (VCD) spectra for conformers of monomeric chiral d(-)-lactic acid and their complexes with water at the DFT(B3LYP)/aug-cc-pVDZ and DFT(B3LYP)/aug-cc-pVTZ levels. A detailed analysis has been performed principally for the two most stable complexes with water, differing by lactic acid conformation. The VCD spectra were found to be sensitive to conformational changes of both free and complexed molecules, and to be especially useful for discriminating between different chiral forms of intermolecular hydrogen bonding complexes. In particular, we show that the VCD modes of an achiral water molecule after complex formation acquire significant rotational strengths whose signs change in line with the geometry of the complex. Using the theoretical prediction, we demonstrate that the VCD technique can be used as a powerful tool for structural investigation of intermolecular interactions of chiral molecules and can yield information complementary to data obtained through other molecular spectroscopy methods.
53 citations
TL;DR: In this paper, the geometry and energy of styrene have been calculated using the 6-31G basis set as a function of the C β C 2 C 1 C 2 dihedral angle.
52 citations