Four- and five-component molecular solids: crystal engineering strategies based on structural inequivalence

A synthetic strategy is described for the co-crystallization of four- and five-component molecular crystals, based on the fact that if any particular chemical constituent of a lower cocrystal is found in two different structural environments, these differences may be exploited to increase the number of components in the solid. 2-Methylresorcinol and tetramethylpyrazine are basic template molecules that allow for further supramolecular homologation. Ten stoichiometric quaternary cocrystals and one quintinary cocrystal with some solid solution character are reported. Cocrystals that do not lend themselves to such homologation are termed synthetic dead ends.

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Odd-Even Effect in the Elastic Modulii of α,ω-Alkanedicarboxylic Acids

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314094480 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C551-C551

Author(s):

Manish Mishra ◽

Sunil Varughese ◽

Upadrasta Ramamurty ◽

Gautam Desiraju

Keyword(s):

Elastic Modulus ◽

Melting Point ◽

Crystal Engineering ◽

Weak Interactions ◽

Molecular Crystals ◽

Relative Strength ◽

Molecular Solids ◽

Structure Property ◽

Depth Of Penetration ◽

Molecular Conformations

Nanoindentation is a probe used to quantitatively assess mechanical behavior of small volume materials. In this technique, load applied vs. the depth of penetration of the indenter into the specimen are measured simultaneously and with high precision and resolution. By analyzing the data, one can obtain the elastic modulus and hardness of crystals. Though this technique has been extensively used to characterize inorganic and engineering materials, we have recently extended its utility to study weak interactions and to establish structure-property relationships in molecular crystals. Being able to assess the relative strength of weak interactions such a technique has become relevant to the subject of crystal engineering which is concerned with the design of molecular solids with desired properties and functions. In our recent studies through nanoindentation on the alkanedicarboxylic acids reveals that the elastic modulus shows similar alternation property as the melting point alternation. Our results are endorsing the strained molecular conformations hypothesis for the melting point alternation of diacids, proposed by Thalladi et al. These results support the development of crystal engineering because nanoindentation may be used as a direct measure of molecular and crystal energies of molecular crystals.

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In situ nanoscale visualization of solvent effects on molecular crystal surfaces

CrystEngComm ◽

10.1039/d1ce00209k ◽

2021 ◽

Author(s):

Mikkel Herzberg ◽

Anders Støttrup Larsen ◽

Tue Hassenkam ◽

Anders Østergaard Madsen ◽

Jukka Rantanen

Keyword(s):

Solid Solution ◽

Solvent Effects ◽

Molecular Crystal ◽

Rational Design ◽

Molecular Level ◽

Molecular Crystals ◽

Crystal Surfaces ◽

Solution Interface ◽

Atomic Force

Solvents can dramatically affect molecular crystals. Obtaining favorable properties for these crystals requires rational design based on molecular level understanding of the solid-solution interface. Here we show how atomic force...

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Midway between Energetic Molecular Crystals and High-Density Energetic Salts: Crystal Engineering with Hydrogen Bonded Chains of Polynitro Bipyrazoles

Crystal Growth & Design ◽

10.1021/acs.cgd.9b01177 ◽

2020 ◽

Vol 20 (2) ◽

pp. 755-764 ◽

Cited By ~ 4

Author(s):

Ivan Gospodinov ◽

Kostiantyn V. Domasevitch ◽

Cornelia C. Unger ◽

Thomas M. Klapötke ◽

Jörg Stierstorfer

Keyword(s):

Crystal Engineering ◽

Molecular Crystals ◽

High Density ◽

Energetic Salts ◽

Hydrogen Bonded

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Associations of squaric acid and its anions as multiform building blocks of hydrogen-bonded molecular crystals

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768101014963 ◽

2001 ◽

Vol 57 (6) ◽

pp. 859-865 ◽

Cited By ~ 46

Author(s):

Gastone Gilli ◽

Valerio Bertolasi ◽

Paola Gilli ◽

Valeria Ferretti

Keyword(s):

Hydrogen Bonds ◽

Crystal Engineering ◽

Negative Charge ◽

Three Dimensional ◽

Molecular Crystals ◽

Building Blocks ◽

Squaric Acid ◽

Orthosilicic Acid ◽

Molecular Plane ◽

Dimensional Crystal

Squaric acid, H2C4O4 (H2SQ), is a completely flat diprotic acid that can crystallize as such, as well as in three different anionic forms, i.e. H2SQ·HSQ−, HSQ− and SQ2−. Its interest for crystal engineering studies arises from three notable factors: (i) its ability of donating and accepting hydrogen bonds strictly confined to the molecular plane; (ii) the remarkable strength of the O—H...O bonds it may form with itself which are either of resonance-assisted (RAHB) or negative-charge-assisted [(−)CAHB] types; (iii) the ease with which it may donate a proton to an aromatic base which, in turn, back-links to the anion by strong low-barrier N—H+...O1/2− charge-assisted hydrogen bonds. Analysis of all the structures so far known shows that, while H2SQ can only crystallize in an extended RAHB-linked planar arrangement and SQ2− tends to behave much as a monomeric dianion, the monoanion HSQ− displays a number of different supramolecular patterns that are classifiable as β-chains, α-chains, α-dimers and α-tetramers. Partial protonation of these motifs leads to H2SQ·HSQ− anions whose supramolecular patterns include ribbons of dimerized β-chains and chains of emiprotonated α-dimers. The topological similarities between the three-dimensional crystal chemistry of orthosilicic acid, H4SiO4, and the two-dimensional one of squaric acid, H2C4O4, are finally stressed.

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Origin and structure of polar domains in doped molecular crystals

Nature Communications ◽

10.1038/ncomms13351 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 18

Author(s):

E. Meirzadeh ◽

I. Azuri ◽

Y. Qi ◽

D. Ehre ◽

A. M. Rappe ◽

...

Keyword(s):

Crystal Engineering ◽

Density Functional ◽

Molecular Crystals ◽

Strong Support ◽

Functional Theory ◽

Guest Molecules ◽

Molecular Dynamics Calculations ◽

Different Temperatures ◽

Global Understanding

Abstract Doping is a primary tool for the modification of the properties of materials. Occlusion of guest molecules in crystals generally reduces their symmetry by the creation of polar domains, which engender polarization and pyroelectricity in the doped crystals. Here we describe a molecular-level determination of the structure of such polar domains, as created by low dopant concentrations (<0.5%). The approach comprises crystal engineering and pyroelectric measurements, together with dispersion-corrected density functional theory and classical molecular dynamics calculations of the doped crystals, using neutron diffraction data of the host at different temperatures. This approach is illustrated using centrosymmetric α-glycine crystals doped with minute amounts of different L-amino acids. The experimentally determined pyroelectric coefficients are explained by the structure and polarization calculations, thus providing strong support for the local and global understanding of how different dopants influence the properties of molecular crystals.

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ChemInform Abstract: Crystal Engineering and Chemical Reactivity of Organic Molecular Solids

Chemischer Informationsdienst ◽

10.1002/chin.198652356 ◽

1986 ◽

Vol 17 (52) ◽

Author(s):

G. R. DESIRAJU

Keyword(s):

Crystal Engineering ◽

Chemical Reactivity ◽

Molecular Solids

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Local similarity in organic crystals and the non-uniqueness of X-ray powder patterns

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768199006114 ◽

1999 ◽

Vol 55 (6) ◽

pp. 1075-1089 ◽

Cited By ~ 9

Author(s):

Heinrich Karfunkel ◽

Heike Wilts ◽

Zhimin Hao ◽

Abul Iqbal ◽

Jin Mizuguchi ◽

...

Keyword(s):

Crystal Engineering ◽

Molecular Solids ◽

Local Similarity ◽

Organic Crystals ◽

Mathematical Operation ◽

Predictive Tool ◽

Theoretical Concepts ◽

X Ray ◽

New Concepts ◽

Structural Database

Two new concepts for molecular solids, `local similarity' and `boundary-preserving isometry', are defined mathematically and a theorem which relates these concepts is formulated. `Locally similar' solids possess an identical short-range structure and a `boundary-preserving isometry' is a new mathematical operation on a finite region of a solid that transforms mathematically a given solid to a locally similar one. It is shown further that the existence of such a `boundary-preserving isometry' in a given solid has infinitely many `locally similar' solids as a consequence. Chemical implications, referring to the similarity of X-ray powder patterns and patent registration, are discussed as well. These theoretical concepts, which are first introduced in a schematic manner, are proved to exist in nature by the elucidation of the crystal structure of some diketopyrrolopyrrole (DPP) derivatives with surprisingly similar powder patterns. Although the available powder patterns were not indexable, the underlying crystals could be elucidated by using the new technique of ab initio prediction of possible polymorphs and a subsequent Rietveld refinement. Further ab initio packing calculations on other molecules reveal that `local crystal similarity' is not restricted to DPP derivatives and should also be exhibited by other molecules such as quinacridones. The `boundary-preserving isometry' is presented as a predictive tool for crystal engineering purposes and attempts to detect it in crystals of the Cambridge Structural Database (CSD) are reported.

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Plasticity in zwitterionic drugs: the bending properties of Pregabalin and Gabapentin and their hydrates

IUCrJ ◽

10.1107/s2052252519004755 ◽

2019 ◽

Vol 6 (4) ◽

pp. 630-634 ◽

Cited By ~ 5

Author(s):

U. B. Rao Khandavilli ◽

Matteo Lusi ◽

Patrick J. Frawley

Keyword(s):

Mechanical Properties ◽

Crystal Engineering ◽

Weak Interactions ◽

Molecular Crystals ◽

Structural Features ◽

Microscopic Structure ◽

Bending Properties ◽

Crystalline Materials ◽

Area Of Interest ◽

Macroscopic Plasticity

The investigation of mechanical properties in molecular crystals is emerging as a novel area of interest in crystal engineering. Indeed, good mechanical properties are required to manufacture pharmaceutical and technologically relevant substances into usable products. In such endeavour, bendable single crystals help to correlate microscopic structure to macroscopic properties for potential design. The hydrate forms of two anticonvulsant zwitterionic drugs, Pregabalin and Gabapentin, are two examples of crystalline materials that show macroscopic plasticity. The direct comparison of these structures with those of their anhydrous counterparts, which are brittle, suggests that the presence of water is critical for plasticity. In contrast, structural features such as molecular packing and anisotropic distribution of strong and weak interactions seem less important.

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