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

1986 ◽  
Vol 17 (52) ◽  
Author(s):  
G. R. DESIRAJU
Keyword(s):  
Crystal Engineering ◽  
Chemical Reactivity ◽  
Molecular Solids

scholarly journals Chemical reactivity at high pressure: the ordered polymerization of oxalic acid

2014 ◽  
Vol 70 (a1) ◽  
pp. C898-C898 ◽  
Author(s):  
Nicola Casati ◽  
Andrew Jephcoat ◽  
Heribert Wilhelm ◽  
Piero Macchi
Keyword(s):  
High Pressure ◽  
Oxalic Acid ◽  
Proton Transfer ◽  
Single Crystal ◽  
Crystal Engineering ◽  
Energetic Materials ◽  
Chemical Reactivity ◽  
Molecular Solids ◽  
Two Phase ◽  
Single Crystal Study

Pressure is known to trigger unusual chemical reactivity in molecular solids. In particular, small molecules containing unsaturated bonds are subject to oligo- or polymerization, effectively synthesizing new compounds. These are tipically energetic materials which can be amorphous, as in the case of carbon monoxide,[1] or crystalline, as for carbon dioxide phase V.[2] In more complex molecular systems, where unsaturated bonds can be only one of the present moieties, stereo-controlled reactivity can be exploited to synthesize topo-tactic structures. We performed a synchrotron single crystal experiment on oxalic acid dihydrate up to 54.7 GPa, using He as pressure transmitting medium to ensure hydrostatic behavior. This is, to the best of our knowledge, the highest pressure ever achieved in a single crystal study on an organic molecule. It had been reported that the species undergoes a proton transfer at mild pressures,[3] and further compression confirms the major role played by hydrogen bonds. After the proton transfer, the species undergoes two phase transitions, caused mainly by a rearrangement of hydrogen bonding patterns, that does not demage the singly crystal nature of the sample. At ~40 GPa an initial bending of the flat oxalic molecule is observed, sign of an enhanced nucleophilic interaction between one oxygen and the carbon of a neighbor molecule. At the highest pressure achieved, a further phase transition is observed. Although the crystallinity is decreased, the new unit cell shows a drastic shrinking in one specific direction. Periodic DFT calculations reveal this metric is compatible with an ordered polymerization of the oxalic acid created by a nucleophilic addition: a monodimensional covalent organic framework is the resulting material (figure). This observation, unique up to now in its kind, is of high relevance for crystal engineering and highlights the potential of high pressure to stimulate new chemistry.

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

1999 ◽  
Vol 55 (6) ◽  
pp. 1075-1089 ◽  
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.

Crystal Engineering of Molecular Solids as Temporary Adhesives

2020 ◽  
Vol 32 (23) ◽  
pp. 9882-9896
Author(s):  
Nicholas D. Blelloch ◽  
Haydn T. Mitchell ◽  
Carly C. Tymm ◽  
Douglas W. Van Citters ◽  
Katherine A. Mirica
Keyword(s):  
Crystal Engineering ◽  
Molecular Solids

6-Propyl-2-thiouracilversus6-methoxymethyl-2-thiouracil: enhancing the hydrogen-bonded synthon motif by replacement of a methylene group with an O atom

2016 ◽  
Vol 72 (8) ◽  
pp. 634-646 ◽  
Author(s):  
Wilhelm Maximilian Hützler ◽  
Ernst Egert ◽  
Michael Bolte
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Engineering ◽  
Rational Design ◽  
Antithyroid Drug ◽  
Chemical Properties ◽  
Structural Similarity ◽  
Molecular Solids ◽  
Hydrogen Bond Acceptor ◽  
Methylene Group

The understanding of intermolecular interactions is a key objective of crystal engineering in order to exploit the derived knowledge for the rational design of new molecular solids with tailored physical and chemical properties. The tools and theories of crystal engineering are indispensable for the rational design of (pharmaceutical) cocrystals. The results of cocrystallization experiments of the antithyroid drug 6-propyl-2-thiouracil (PTU) with 2,4-diaminopyrimidine (DAPY), and of 6-methoxymethyl-2-thiouracil (MOMTU) with DAPY and 2,4,6-triaminopyrimidine (TAPY), respectively, are reported. PTU and MOMTU show a high structural similarity and differ only in the replacement of a methylene group (–CH2–) with an O atom in the side chain, thus introducing an additional hydrogen-bond acceptor in MOMTU. Both molecules contain anADAhydrogen-bonding site (A= acceptor andD= donor), while the coformers DAPY and TAPY both show complementaryDADsites and therefore should be capable of forming a mixedADA/DADsynthon with each other,i.e. N—H...O, N—H...N and N—H...S hydrogen bonds. The experiments yielded one solvated cocrystal salt of PTU with DAPY, four different solvates of MOMTU, one ionic cocrystal of MOMTU with DAPY and one cocrystal salt of MOMTU with TAPY, namely 2,4-diaminopyrimidinium 6-propyl-2-thiouracilate–2,4-diaminopyrimidine–N,N-dimethylacetamide–water (1/1/1/1) (the systematic name for 6-propyl-2-thiouracilate is 6-oxo-4-propyl-2-sulfanylidene-1,2,3,6-tetrahydropyrimidin-1-ide), C4H7N4+·C7H9N2OS−·C4H6N4·C4H9NO·H2O, (I), 6-methoxymethyl-2-thiouracil–N,N-dimethylformamide (1/1), C6H8N2O2S·C3H7NO, (II), 6-methoxymethyl-2-thiouracil–N,N-dimethylacetamide (1/1), C6H8N2O2S·C4H9NO, (III), 6-methoxymethyl-2-thiouracil–dimethyl sulfoxide (1/1), C6H8N2O2S·C2H6OS, (IV), 6-methoxymethyl-2-thiouracil–1-methylpyrrolidin-2-one (1/1), C6H8N2O2S·C5H9NO, (V), 2,4-diaminopyrimidinium 6-methoxymethyl-2-thiouracilate (the systematic name for 6-methoxymethyl-2-thiouracilate is 4-methoxymethyl-6-oxo-2-sulfanylidene-1,2,3,6-tetrahydropyrimidin-1-ide), C4H7N4+·C6H7N2O2S−, (VI), and 2,4,6-triaminopyrimidinium 6-methoxymethyl-2-thiouracilate–6-methoxymethyl-2-thiouracil (1/1), C4H8N5+·C6H7N2O2S−·C6H8N2O2S, (VII). Whereas in (I) only anAA/DDhydrogen-bonding interaction was formed, the structures of (VI) and (VII) both display the desiredADA/DADsynthon. Conformational studies on the side chains of PTU and MOMTU also revealed a significant deviation for cocrystals (VI) and (VII), leading to the desired enhancement of the hydrogen-bond pattern within the crystal.

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

IUCrJ ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. 96-101 ◽  
Author(s):  
Niyaz A. Mir ◽  
Ritesh Dubey ◽  
Gautam R. Desiraju
Keyword(s):  
Solid Solution ◽  
Crystal Engineering ◽  
Molecular Crystals ◽  
Chemical Constituent ◽  
Molecular Solids ◽  
Number Of Components ◽  
Synthetic Strategy

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.

scholarly journals 21st century developments in the understanding and control of molecular solids

2018 ◽  
Vol 54 (94) ◽  
pp. 13175-13182 ◽  
Author(s):  
Jonathan W. Steed
Keyword(s):  
21St Century ◽  
Crystal Engineering ◽  
Amorphous Materials ◽  
Molecular Solids ◽  
Recent Advances ◽  
And Control

This highlight article surveys some of the key recent advances in crystallization techniques, polymorphism, co-crystals, amorphous materials and crystal engineering.

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

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.

Shape and size mimicry in the design of ternary molecular solids: towards a robust strategy for crystal engineering

2011 ◽  
Vol 47 (44) ◽  
pp. 12080 ◽  
Author(s):  
Srinu Tothadi ◽  
Arijit Mukherjee ◽  
Gautam R. Desiraju
Keyword(s):  
Crystal Engineering ◽  
Molecular Solids ◽  
Shape And Size

Understanding Supramolecular Interactions Provides Clues for Building Molecules into Minerals and Materials: a Retrosynthetic Analysis of Copper-Based Solids

2010 ◽  
Vol 63 (4) ◽  
pp. 565 ◽  
Author(s):  
Monika Singh ◽  
Jency Thomas ◽  
Arunachalam Ramanan
Keyword(s):  
Crystal Engineering ◽  
Crystal Packing ◽  
Ionic Species ◽  
Supramolecular Interactions ◽  
Molecular Solids ◽  
Mechanistic Approach ◽  
Retrosynthetic Analysis ◽  
First Time ◽  
Covalent Interactions

The influence of non-covalent interactions on the crystal packing of molecules is well documented in the literature. Unlike molecular solids, crystal engineering of non-molecular solids is difficult to interpret as aggregation is complicated by the presence of neutral as well as ionic species and a range of forces operating, from weak hydrogen bonding to strong covalent interactions. In this perspective, we demonstrate for the first time the role of non-bonding interactions in the occurrence of oxide, hydroxide, or chloride linkages in oxides, hydroxychlorides, and chlorides of copper-based minerals and coordination polymers in terms of a mechanistic approach based on supramolecular retrosynthesis. The model proposed here visualizes the crystal nucleus as a supramolecular analogue of a transition state wherein appropriate tectons (chemically reasonable molecules) aggregate through non-bonding forces that can be perceived through well-known supramolecular synthons. The mechanistic approach provides chemical insights into the occurrence of different topologies and solid-state phenomena like polymorphism.

Spatially Resolved Photoelectron Spectroscopy: Recent Progress and Future Plans

1990 ◽  
Vol 48 (2) ◽  
pp. 388-389
Author(s):  
A. M. Bradshaw
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Reactivity ◽  
Target Material ◽  
Orbital Energy ◽  
Light Sources ◽  
Analytical Technique ◽  
Hartree Fock ◽  
Spatially Resolved ◽  
Koopmans Theorem ◽  
Surface Analytical Technique

X-ray photoelectron spectroscopy (XPS or ESCA) was not developed by Siegbahn and co-workers as a surface analytical technique, but rather as a general probe of electronic structure and chemical reactivity. The method is based on the phenomenon of photoionisation: The absorption of monochromatic radiation in the target material (free atoms, molecules, solids or liquids) causes electrons to be injected into the vacuum continuum. Pseudo-monochromatic laboratory light sources (e.g. AlKα) have mostly been used hitherto for this excitation; in recent years synchrotron radiation has become increasingly important. A kinetic energy analysis of the so-called photoelectrons gives rise to a spectrum which consists of a series of lines corresponding to each discrete core and valence level of the system. The measured binding energy, EB, given by EB = hv−EK, where EK is the kineticenergy relative to the vacuum level, may be equated with the orbital energy derived from a Hartree-Fock SCF calculation of the system under consideration (Koopmans theorem).

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