Inter- and intramolecular bonding in 1,3,5-triamino-2,4,6-trinitrobenzene: An experimental and theoretical quantum theory of atoms in molecules (QTAIM) analysis
Chemical bonding in the triclinic phase of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) has been analyzed based on the experimental electron density derived from X-ray diffraction data obtained at 20 K. The results have been compared with those from solid state theoretical calculations. The total electron density has been analyzed in terms of the Quantum Theory of Atoms in Molecules (QTAIM). Features of the covalent bonds demonstrate the presence of multiple bonds of various order. Strong intramolecular hydrogen bonds and weaker intermolecular bonds within the layer structure are characterized by the properties of their (3, −1) critical points. Weaker interactions, predominantly O···O, betwe…
Revised structure of trans-resveratrol: Implications for its proposed antioxidant mechanism
The crystal structure of trans-resveratrol has been redetermined by X-ray diffraction. The newly refined structure demonstrates that the previously reported, dynamically disordered hydrogen-bonding network is rather the superposition of two crystallographically independent molecules of trans-resveratrol. This latter arrangement possesses a well-defined hydrogen-bonding network in a unit cell of double the previously reported volume. While not meant as a criticism of the proposed antioxidant mechanism itself, the present studies clearly show that the X-ray diffraction data should no longer be used for its additional support.
X-ray, conformation and electronic structures of 1-nitropyrrolidine
Abstract The chemistry of pyrrolidine compounds has drawn much attention because of their biological activities. The crystal and molecular structure of 1-nitropyrrolidine (C4H8NNO2) at 150K, along with calculated structures (DFT and MP2), are reported herein. In the solid-state, the asymmetric part of the unit cell is composed of one quartermolecule at the position of two perpendicular mirror planes and the five-membered ring is disordered over a mirror plane, revealing the twisted conformation. Both geometries suggest slight sp3 hybridization of the amine nitrogen atom. The non-planar geometry suggests the lack of conjugation of the amine nitrogen lone pair with the nitro group, however th…
Experimental and Theoretical Electron Density Determination for Two Norbornene Derivatives: Topological Analysis Provides Insights on Reactivity
The electron density distribution of two substituted norbornene derivatives (cis-5-norbornene-endo-2,3-dicarboxylic anhydride (1) and 7-oxabicylo[2.2.1]hept-5-ene-exo-2,3-dicarboxylic anhydride (2) has been determined from low-temperature (20 K) X-ray diffraction data and from DFT calculations with periodic boundary conditions. Topological analysis of the electron density is discussed with respect to exo-selective additions, the partial retro-Diels-Alder (rDA) character of the ground state, and intermolecular interaction energies.
Self-assembly mechanism based on charge density topological interaction energies
The packing interactions have been evaluated in the context of the self-assembly mechanism of crystal growth and also for its impacts on the aromaticity of the trimesate anion. The structure of ethylammonium trimesate hydrate (1) measured at 100 K and a charge density model, derived in part from theoretical structures, is reported. Theoretical structure factors were obtained from the geometry-optimized periodic wave function. The trimesic acid portion of 1 is fully deprotonated and participates in a variety hydrogen bonding motifs. Topological analysis of the charge density model reveals the most significant packing interactions and is then compared to a complementary analysis performed by …
Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K
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 si…
CCDC 1508075: Experimental Crystal Structure Determination
Related Article: Christopher G. Gianopoulos, Bartosz Zarychta, Simone Cenedese, Vladimir V. Zhurov, A. Alan Pinkerton|2016|J.Phys.Chem.A|120|4059|doi:10.1021/acs.jpca.6b03787
CCDC 1549795: Experimental Crystal Structure Determination
Related Article: Zhijie Chua, Christopher G. Gianopoulos, Bartosz Zarychta, Elizabeth A. Zhurova, Vladimir V. Zhurov, and A. Alan Pinkerton|2017|Cryst.Growth Des.|17|5200|doi:10.1021/acs.cgd.7b00674
CCDC 1430837: Experimental Crystal Structure Determination
Related Article: Błażej Dziuk, Christopher G. Gianopoulos, Krzysztof Ejsmont, Bartosz Zarychta|2018|Struct.Chem.|29|703|doi:10.1007/s11224-017-1060-6
CCDC 1508074: Experimental Crystal Structure Determination
Related Article: Christopher G. Gianopoulos, Bartosz Zarychta, Simone Cenedese, Vladimir V. Zhurov, A. Alan Pinkerton|2016|J.Phys.Chem.A|120|4059|doi:10.1021/acs.jpca.6b03787
CCDC 1440764: Experimental Crystal Structure Determination
Related Article: Bartosz Zarychta, Christopher G. Gianopoulos, A. Alan Pinkerton|2016|Bioorg.Med.Chem.Lett.|26|1416|doi:10.1016/j.bmcl.2016.01.070
CCDC 1409554: Experimental Crystal Structure Determination
Related Article: Katarzyna Gajda, Krzysztof Ejsmont, Zdzisław Daszkiewicz, Christopher G. Gianopoulos, Bartosz Zarychta|2016|J.Mol.Struct.|1108|590|doi:10.1016/j.molstruc.2015.12.050