scholarly journals Accurate Lattice Energies for Molecular Crystals from Experimental Crystal Structures

2018 ◽  
Vol 14 (3) ◽  
pp. 1614-1623 ◽  
Author(s):  
Sajesh P. Thomas ◽  
Peter R. Spackman ◽  
Dylan Jayatilaka ◽  
Mark A. Spackman
Keyword(s):  
Crystal Structures ◽  
Molecular Crystals ◽  
Lattice Energies ◽  
Experimental Crystal

scholarly journals An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics

2016 ◽  
Vol 72 (4) ◽  
pp. 477-487 ◽  
Author(s):  
Edward O. Pyzer-Knapp ◽  
Hugh P. G. Thompson ◽  
Graeme M. Day
Keyword(s):  
Force Field ◽  
Crystal Structures ◽  
Force Fields ◽  
Molecular Crystals ◽  
Intermolecular Force ◽  
Organic Molecular Crystals ◽  
Organic Solid ◽  
Lattice Energies ◽  
Validation Set ◽  
Unit Cell Dimensions

We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%.

Crystal and molecular structures of boldenone and four boldenone steroid esters

2019 ◽  
Vol 234 (10) ◽  
pp. 671-683 ◽  
Author(s):  
Alexandru Turza ◽  
Maria O. Miclăuș ◽  
Aurel Pop ◽  
Gheorghe Borodi
Keyword(s):  
Crystal Structures ◽  
High Throughput ◽  
High Throughput Screening ◽  
Molecular Structures ◽  
Anabolic Androgenic Steroid ◽  
Crystal And Molecular Structures ◽  
Hirshfeld Surfaces ◽  
Intermolecular Contacts ◽  
Lattice Energies ◽  
Steroid Skeleton

Abstract Androsta-1,4-dien-17β-ol-3-one, also known as boldenone, is an anabolic-androgenic steroid derived from testosterone. The crystal structures of boldenone base, boldenone acetate, boldenone propionate, boldenone cypionate and a boldenone acetate polymorph obtained by high throughput screening were investigated. Hirshfeld surfaces and fingerprint plots breakdown revealed that the molecular packing in the crystals are driven by dominant H⋯H intermolecular contacts, followed by O⋯H/H⋯O contacts and to a lesser degree C⋯H/H⋯C contacts. The steroid skeleton rings, for all the reported compounds, adopt the following conformation: planar in A, chair in B and C, whereas C(13) envelope conformations are found for the five-membered D rings. The total lattice energies were calculated as a sum of four terms (Coulombic, polarization, dispersion, repulsion).

scholarly journals Revised values for the X23 benchmark set of molecular crystals

2019 ◽  
Vol 21 (44) ◽  
pp. 24333-24344 ◽  
Author(s):  
Grygoriy A. Dolgonos ◽  
Johannes Hoja ◽  
A. Daniel Boese
Keyword(s):  
Thermal Effects ◽  
Molecular Crystals ◽  
Reference Value ◽  
Zero Point ◽  
Zero Point Energy ◽  
Point Energy ◽  
Value Set ◽  
Volumetric Expansion ◽  
Lattice Energies ◽  
Cell Volumes

A revised reference value set for molecular crystals: X23b; new cell volumes and lattice energies including volumetric expansion due to zero-point energy and thermal effects.

scholarly journals Validation of experimental molecular crystal structures with dispersion-corrected density functional theory calculations

2010 ◽  
Vol 66 (5) ◽  
pp. 544-558 ◽  
Author(s):  
Jacco van de Streek ◽  
Marcus A. Neumann
Keyword(s):  
Density Functional Theory ◽  
Crystal Structures ◽  
Density Functional ◽  
Unit Cell ◽  
Organic Crystal ◽  
Large Temperature ◽  
Unit Cell Parameters ◽  
Functional Theory ◽  
Cell Parameters ◽  
Experimental Crystal

This paper describes the validation of a dispersion-corrected density functional theory (d-DFT) method for the purpose of assessing the correctness of experimental organic crystal structures and enhancing the information content of purely experimental data. 241 experimental organic crystal structures from the August 2008 issue of Acta Cryst. Section E were energy-minimized in full, including unit-cell parameters. The differences between the experimental and the minimized crystal structures were subjected to statistical analysis. The r.m.s. Cartesian displacement excluding H atoms upon energy minimization with flexible unit-cell parameters is selected as a pertinent indicator of the correctness of a crystal structure. All 241 experimental crystal structures are reproduced very well: the average r.m.s. Cartesian displacement for the 241 crystal structures, including 16 disordered structures, is only 0.095 Å (0.084 Å for the 225 ordered structures). R.m.s. Cartesian displacements above 0.25 Å either indicate incorrect experimental crystal structures or reveal interesting structural features such as exceptionally large temperature effects, incorrectly modelled disorder or symmetry breaking H atoms. After validation, the method is applied to nine examples that are known to be ambiguous or subtly incorrect.

Predicted and experimental crystal structures of ethyl-tert-butyl ether

2011 ◽  
Vol 67 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Sonja M. Hammer ◽  
Edith Alig ◽  
Lothar Fink ◽  
Martin U. Schmidt
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Global Minimum ◽  
Lattice Energy ◽  
Real Space ◽  
Energy Structure ◽  
Butyl Ether ◽  
Crystallization Experiments ◽  
Rank 2 ◽  
Experimental Crystal

Possible crystal structures of ethyl-tert-butyl ether (ETBE) were predicted by global lattice-energy minimizations using the force-field approach. 33 structures were found within an energy range of 2 kJ mol−1 above the global minimum. Low-temperature crystallization experiments were carried out at 80–160 K. The crystal structure was determined from X-ray powder data. ETBE crystallizes in C2/m, Z = 4, with molecules on mirror planes. The ETBE molecule adopts a trans conformation with a (CH3)3C—O—C—C torsion angle of 180°. The experimental structure corresponds with high accuracy to the predicted structure with energy rank 2, which has an energy of 0.54 kJ mol−1 above the global minimum and is the most dense low-energy structure. In some crystallization experiments a second polymorph was observed, but the quality of the powder data did not allow the determination of the crystal structure. Possibilities and limitations are discussed for solving crystal structures from powder diffraction data by real-space methods and lattice-energy minimizations.

Adamantane derivatives of sulfonamide molecular crystals: structure, sublimation thermodynamic characteristics, molecular packing, and hydrogen bond networks

CrystEngComm ◽  
2015 ◽  
Vol 17 (4) ◽  
pp. 753-763 ◽  
Author(s):  
German L. Perlovich ◽  
Alex M. Ryzhakov ◽  
Valery V. Tkachev ◽  
Alexey N. Proshin
Keyword(s):  
Hydrogen Bond ◽  
Crystal Structures ◽  
Molecular Crystals ◽  
Thermodynamic Characteristics ◽  
Molecular Packing ◽  
Adamantane Derivatives ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Bond Networks ◽  
Derivatives Of

The crystal structures of six adamantane derivatives of sulfonamides have been determined by X-ray diffraction and their sublimation and fusion processes have been studied.

Predicted crystal structures of tetramethylsilane and tetramethylgermane and an experimental low-temperature structure of tetramethylsilane

2010 ◽  
Vol 66 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Alexandra K. Wolf ◽  
Jürgen Glinnemann ◽  
Lothar Fink ◽  
Edith Alig ◽  
Michael Bolte ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Crystal Structures ◽  
Ambient Pressure ◽  
Lattice Energy ◽  
Energy Structure ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Field Methods ◽  
Experimental Crystal

No crystal structure at ambient pressure is known for tetramethylsilane, Si(CH3)4, which is used as a standard in NMR spectroscopy. Possible crystal structures were predicted by global lattice-energy minimizations using force-field methods. The lowest-energy structure corresponds to the high-pressure room-temperature phase (Pa\overline{3}, Z = 8). Low-temperature crystallization at 100 K resulted in a single crystal, and its crystal structure has been determined. The structure corresponds to the predicted structure with the second lowest energy rank. In X-ray powder analyses this is the only observed phase between 80 and 159 K. For tetramethylgermane, Ge(CH_3)_4, no experimental crystal structure is known. Global lattice-energy minimizations resulted in 47 possible crystal structures within an energy range of 5 kJ mol−1. The lowest-energy structure was found in Pa\overline{3}, Z = 8.

Engineering crystals that facilitate the acyl-transfer reaction: insight from a comparison of the crystal structures ofmyo-inositol-1,3,5-orthoformate-derived benzoates and carbonates

2016 ◽  
Vol 72 (11) ◽  
pp. 875-881 ◽  
Author(s):  
Majid I. Tamboli ◽  
Shobhana Krishanaswamy ◽  
Rajesh G. Gonnade ◽  
Mysore S. Shashidhar
Keyword(s):  
Molecular Structure ◽  
Crystal Structures ◽  
Transfer Reaction ◽  
Molecular Crystals ◽  
Considerable Change ◽  
Chemical Processes ◽  
Acyl Transfer ◽  
The Relationship ◽  
Reactivity Insertion ◽  
Orientation Of Molecules

Minor variations in the molecular structure of constituent molecules of reactive crystals often yield crystals with significantly different properties due to altered modes of molecular association in the solid state. Hence, these studies could provide a better understanding of the complex chemical processes occurring in the crystalline state. However, reactions that proceed efficiently in molecular crystals are only a small fraction of the reactions that are known to proceed (with comparable efficiency) in the solution state. Hence, for consistent progress in this area of research, investigation of newer reactive molecular crystals which support different kinds of reactions and their related systems is essential. The crystal structures and acyl-transfer reactivity of amyo-inositol-1,3,5-orthoformate-derived dibenzoate and its carbonate (4-O-benzoyl-2-O-phenoxycarbonyl-myo-inositol 1,3,5-orthoformate, C21H18O9) and thiocarbonate (4-O-benzoyl-2-O-phenoxythiocarbonyl-myo-inositol 1,3,5-orthoformate, C21H18O8S) analogs are compared with the aim of understanding the relationship between crystal structure and acyl-transfer reactivity. Insertion of an O atom in the acyl (or thioacyl) group of an ester gives the corresponding carbonate (or thiocarbonate). This seemingly minor change in molecular structure results in a considerable change in the packing of the molecules in the crystals ofmyo-inositol-1,3,5-orthoformate-derived benzoates and the corresponding carbonates. These differences result in a lack of intermolecular acyl-transfer reactivity in crystals ofmyo-inositol-1,3,5-orthoformate-derived carbonates. Hence, this study illustrates the sensitivity of the relative orientation of molecules, their packing and ensuing changes in the reactivity of resulting crystals to minor changes in molecular structure.

A combined experimental and theoretical study of miconazole salts and cocrystals: crystal structures, DFT computations, formation thermodynamics and solubility improvement

2021 ◽  
Author(s):  
Ksenia V. Drozd ◽  
Alex N. Manin ◽  
Alexander P. Voronin ◽  
Denis Boycov ◽  
Churakov Andrei ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Theoretical Study ◽  
Molecular Crystals ◽  
Dicarboxylic Acids ◽  
Antifungal Drug ◽  
Crystal Forms ◽  
Dft Computations ◽  
Solubility Improvement ◽  
Aliphatic Dicarboxylic Acids ◽  
Formation Thermodynamics

Experimental and theoretical screening of multi-component crystal forms of miconazole (MCL), an antifungal drug, with ten aliphatic dicarboxylic acids was performed. Seven multi-component molecular crystals were isolated and identified by...

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