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Structures of the lattice inclusion hosts 1-3 and their 0-dimensional self-assemblies with void spaces occupied by guest species.
Source publication
The macroscopic properties of organic solids are largely dictated by organization of the constituent molecules in the crystal lattice. It is thus possible to control bulk properties of organic solids in a bottom-up approach by programming the constituent molecules to undergo self assembly in a specific fashion. Molecular recognition lies at the hea...
Contexts in source publication
Context 1
... benzoic acid with the triphenyl- methyl group at the para position was shown to self assemble with adoption of the dimer synthon to yield a wheel-and-axle type supermolecule, which crystallizes out with inclusion of a variety of aromatic guests such as o-, m-and p-xylenes, chlorobenzene, bromobenzene, mesitylene, ani- sole and nitrobenzene. In Figure 2 is shown the assembly observed in which the dimeric asso- ciation of 4-tritylbenzoic acid leads to the inclu- sion of one of the guest molecules, i.e., p-xylene. Clearly, the dimeric association of 4-tritylbenzoic acid to mimic the lattice inclusion phenomenon of a unique class of inclusion host compounds should constitute a brilliant example of crystal engineering, whereby the solid state behavior, namely lattice inclusion, is achieved by a rational design of molecular module that exploits the acid dimer motif. ...
Context 2
... The bulky and twisted aromatic rings restrict the molecules from undergoing close packing leading to looser aggregation of molecules, while the COOH groups act as binding sites that aid in the propaga- tion of the network via acid dimer motif forming a host matrix for inclusion of suitable guest mol- ecules. In its inclusion compound with dioxane, four molecules of the diacid 2 are found to form a hydrogen-bonded tetramer via the acid dimer synthon, Figure 2. The resultant supramolecular macrocycles are filled by the disordered dioxane guests. ...
Context 3
... The third constitutes the case of an isophthalic acid derivative 3. Although the preferred self-assem- bly of isophthalic acid in the solid state should lead to a zigzag ribbon (vide infra), it has been demon- strated that insulated hexagonal honeycomb cages formed by acid dimer-mediated aggregation of six building blocks have been shown to be engineered with 5-hydroxyisophthalic acid; in the cavities of the resultant aggregates, hydrated 18-crown-6 guests species are shown to be nested (Figure 2). 24 The water is found to be a decameric cluster that is centrosymmetric and fully ordered with the con- nectivity resembling that of the carbon skeleton of a bishomocubane with the methylene bridges replacing opposite C-C bonds of cubane. ...
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Citations
It is particularly appropriate that the Journal of the Indian Institute of Science is bringing out a commemorative issue to mark the International Year of Crystallography 2014 (IYCr2014). India has had a strong crystallographic tradition, and the earliest work in what may be described as structural crystallography from this country is the work of K. Banerjee on the determination of the crystal structure of naphthalene in 1930.1 The Indian Institute of Science itself has played no small part in establishing and sustaining the subject of crystallography in this country. A large number of papers in this special issue are written by authors who have either have been trained in the Institute or who have some kindof professional association with this organization. In this article I will tryto capture some unique features that characterize the intersection of the crystallographic and the chemical domains, mostly as they pertain to the Indian contribution to this subject. Crystallography is of course is as old as chemistry itself, and some would say it is even older. The relationships between chemistry and crystallography go back to much before the discovery of diffraction of X-rays by crystals. 2 The discovery of polymorphism by Mitscherlisch in 1822,3 Haüy's formulation of the molecule integrante,4 and the work of Fedorov5 and Groth6 on the identification of crystals from their morphology alone, are well known examples of such relationships.A very early article by Tutton speaks of "crystallo-chemical analysis".7 In this article, I shall, however, be dealing with the interplay of chemistry and crystallography only in the post diffraction era, that is, after 1912. Much had been written and said about chemical crystallography, and even within the context of the present special issue, there is a review of chemical crystallography in India including some futuristic trends.8 This topic was also reviewed by Nangia in a special publication brought out by Indian Academy of Sciences in 2009,9 and by Desiraju in a special publication10 brought out by the Indian National Science Academy in 2010. Arather detailed account of crystallography in India appeared in 2007 inthe newsletter of the International Union of Crystallography (IUCr) in whichchemical crystallography was detailed. 11 Since all these publications are fairly recent there is little need for me to attempt a comprehensive coverage of chemical crystallography in India in this short review.
Self-assembly of sterically-rigidified 3-connecting benzenetribenzoic acid into (6,3) and (3,3) nets and stabilization of water channel in the crystal lattice a A rigid 3-connecting triacid MeBTB was designed and synthesized in the quest of guest inclusion in the pores of honeycomb network structures generated based on the acid dimer-mediated self-assembly. Crystallization of MeBTB is indeed found to lead to a (6,3) net that is 3-fold interpenetrated. Charge-assisted hydrogen bond-mediated self-assembly in the presence of KX/dibenzo-18-crown-6 is likewise found to lead to a (3,3) honeycomb net, which is also 3-fold interpenetrated. When contrasted with the results of self-assembly of sterically-unhindered 1,3,5-benzenetribenzoic acid 2 and those of analogous tribenzoic acid based on mesitylene, that is MTB, the sterics built into the structure of MeBTB allow engineering of ordered assemblies with reduced interpenetration and higher solvent-accessible volumes. A limited, yet meaningful number of structures demonstrates the fact that the rigid building blocks, while responding to the expectations based on aggregation via acid dimer synthon, are most likely to present rich diversity in terms of synthon adoptions and bring up surprises in the self-assembly through inclusion of adventitious water. Crystallization of MeBTB in MeOH–DME led to a disappearing solvate form in which the helically organized acids are found to sustain a water channel.
