Related Experiment Video
Updated: Aug 11, 2026
08:44
Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene
Published on: August 22, 2017
Electrostatic properties of beta-cytidine and cytosine monohydrate from Bragg diffraction
1Department of Crystallography, University of Pittsburgh, PA 15260, USA.
Acta Crystallographica. Section B, Structural Science
|December 1, 1995
Summary
Charge-density distribution in beta-cytidine was determined using X-ray diffraction. Electrostatic potential maps reveal similarities to cytosine monohydrate, with implications for molecular properties and charge distributions.
Area of Science:
- Crystallography
- Quantum Chemistry
- Molecular Modeling
Background:
- Accurate charge-density distribution is crucial for understanding molecular interactions and properties.
- Previous studies on cytosine derivatives provided foundational data for electrostatic potential mapping.
Purpose of the Study:
- To determine the charge-density distribution in beta-cytidine at 123 K.
- To compare electrostatic potential maps of cytidine with related cytosine compounds.
- To refine structure determination methods using pseudoatom multipole refinements.
Main Methods:
- X-ray diffraction data collection (Ag K alpha, lambda = 0.5608 A).
- Pseudoatom multipole refinements, including kappa as a variable.
- Structure refinement of beta-cytidine and cytosine monohydrate.
Main Results:
- Electrostatic potential maps for the cytosine base in cytidine are comparable to those of cytosine monohydrate and 1-beta-D-arabinosyl-cytosine.
- The kappa value for hydrogen is not well-determined experimentally and affects population parameters.
- Calculated molecular dipole moments for cytidine and cytosine monohydrate were 17(4) and 8.2(15) Debye, respectively, using an average theoretical kappa H.
Conclusions:
- The charge-density distribution in beta-cytidine is consistent with related cytosine structures.
- Experimental determination of kappa values for hydrogen requires careful consideration due to their variability.
- Atomic point charge systems provide satisfactory reproduction of experimental electrostatic potentials and dipole moments.
Related Concept Videos
02:18X-ray Crystallography
The size of the unit cell and the arrangement of atoms in a crystal may be determined from measurements of the diffraction of X-rays by the crystal, termed X-ray crystallography.
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
01:10X-ray Diffraction of Biological Samples
X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...