The experimental charge-density approach in the evaluation of intermolecular interactions. Application of a new module of theXDprogramming package to several solids including a pentapeptide

Experimental charge density analysis combined with the quantum crystallographic technique of X-ray wavefunction refinement (XWR) provides quantitative insights into the intra- and intermolecular interactions formed by acetazolamide, a diuretic drug.

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Trans-cinnamic acid and coumarin-3-carboxylic acid: experimental charge-density studies to shed light on [2 + 2] cycloaddition reactions

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768109001566 ◽

2009 ◽

Vol 65 (2) ◽

pp. 230-237 ◽

Cited By ~ 25

Author(s):

Judith A. K. Howard ◽

Mary F. Mahon ◽

Paul R. Raithby ◽

Hazel A. Sparkes

Keyword(s):

Solid State ◽

Carboxylic Acid ◽

Charge Density ◽

Intermolecular Interactions ◽

Cinnamic Acid ◽

Cycloaddition Reactions ◽

X Ray Diffraction ◽

Resolution Single ◽

Experimental Charge Density ◽

Shed Light

As part of an ongoing series of experimental charge-density investigations into the intra- and intermolecular interactions present in compounds which undergo solid-state [2 + 2] cycloaddition reactions, the charge-density analyses of trans-cinnamic acid and coumarin-3-carboxylic acid are reported. Thus, high-resolution single-crystal X-ray diffraction data were recorded at 100 K for trans-cinnamic acid (sin θ/λmax = 1.03 Å−1) and coumarin-3-carboxylic acid (sin θ/λmax = 1.19 Å−1). In addition to the anticipated O—H...O hydrogen bonds weak C—H...O interactions were identified in both structures along with very weak intermolecular interactions between pairs of molecules that undergo solid-state [2 + 2] cycloaddition reactions upon irradiation.

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Is there a future for topological analysis in experimental charge-density research?

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520617006680 ◽

2017 ◽

Vol 73 (3) ◽

pp. 325-329 ◽

Cited By ~ 6

Author(s):

Birger Dittrich

Keyword(s):

Charge Density ◽

Intermolecular Interaction ◽

Intermolecular Interactions ◽

Chemical Bonding ◽

Topological Analysis ◽

Theoretical Chemistry ◽

Research Tool ◽

Interaction Energies ◽

Research Focus ◽

Experimental Charge Density

Topological analysis using Bader and co-worker'sAtoms in Moleculestheory has seen many applications in theoretical chemistry and experimental charge-density research. A brief overview of successful early developments, establishing topological analysis as a research tool for characterizing intramolecular chemical bonding, is provided. A lack of vision in many `descriptive but not predictive' subsequent studies is discussed. Limitations of topology for providing accurate energetic estimates of intermolecular interaction energies are put into perspective. It is recommended that topological analyses of well understood bonding situations are phased out and are only reported for unusual bonding. Descriptive studies of intermolecular interactions should have a clear research focus.

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Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520617007363 ◽

2017 ◽

Vol 73 (4) ◽

pp. 654-659 ◽

Cited By ~ 3

Author(s):

Zhijie Chua ◽

Bartosz Zarychta ◽

Christopher G. Gianopoulos ◽

Vladimir V. Zhurov ◽

A. Alan Pinkerton

Keyword(s):

Charge Density ◽

Electron Density ◽

Topological Analysis ◽

Diffraction Measurement ◽

X Ray Diffraction ◽

Total Electron Density ◽

Total Electron ◽

Structure Factors ◽

Density Analysis ◽

Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

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