Crystal engineering and <b>IUCrJ</b>

Desiraju, Gautam R.

doi:10.1107/s2052252515024100

Cited by 16 publications

(11 citation statements)

References 5 publications

(4 reference statements)

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“…In an answer, Lecomte et al [171] argued that individual atom-atom pair interactions (of atoms in a crystal) are structure determining, and thus are responsible for the entire structure of the chemical system being examined. In our view, which may be in accord with that of Desiraju [173], the packing between molecular domains in crystals is closely related with the atom-atom contact distances; this, together with the directionalities involved, collectively determine the energies of these contacts. Clearly, these three features, together with lattice forces, and sometimes solvation, are often examined to determine the way and the extent to which an intermolecular interaction drives packing of molecules in a crystal.…”

Section: Is An Atom-atom Contact a Bond (Or An Interaction)?supporting

confidence: 79%

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

2019

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In addition to the underlying basic concepts and early recognition of halogen bonding, this paper reviews the conflicting views that consistently appear in the area of noncovalent interactions and the ability of covalently bonded halogen atoms in molecules to participate in noncovalent interactions that contribute to packing in the solid-state. It may be relatively straightforward to identify Type-II halogen bonding between atoms using the conceptual framework of σ-hole theory, especially when the interaction is linear and is formed between the axial positive region (σ-hole) on the halogen in one monomer and a negative site on a second interacting monomer. A σ-hole is an electron density deficient region on the halogen atom X opposite to the R–X covalent bond, where R is the remainder part of the molecule. However, it is not trivial to do so when secondary interactions are involved as the directionality of the interaction is significantly affected. We show, by providing some specific examples, that halogen bonds do not always follow the strict Type-II topology, and the occurrence of Type-I and -III halogen-centered contacts in crystals is very difficult to predict. In many instances, Type-I halogen-centered contacts appear simultaneously with Type-II halogen bonds. We employed the Independent Gradient Model, a recently proposed electron density approach for probing strong and weak interactions in molecular domains, to show that this is a very useful tool in unraveling the chemistry of halogen-assisted noncovalent interactions, especially in the weak bonding regime. Wherever possible, we have attempted to connect some of these results with those reported previously. Though useful for studying interactions of reasonable strength, IUPAC’s proposed “less than the sum of the van der Waals radii” criterion should not always be assumed as a necessary and sufficient feature to reveal weakly bound interactions, since in many crystals the attractive interaction happens to occur between the midpoint of a bond, or the junction region, and a positive or negative site.

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Section: Is An Atom-atom Contact a Bond (Or An Interaction)?supporting

confidence: 79%

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

2019

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“…It involves rational design (functionalization) of simple molecular building blocks, and their self‐assembly into attractive crystalline architectures. It is based on understanding of the strength and directionality of non‐covalent intermolecular interactions that operate between molecular building units . Co‐crystals represent another example of supramolecular materials characterizable in the solid state .…”

Section: Introductionmentioning

confidence: 99%

“…It is based on understanding of the strength and directionality of non-covalent intermolecular interactions that operate between molecular building units. [6] Co-crystals represent another example of supramolecular materials characterizable in the solid state. [7] These are of a particular interest to pharmaceutical chemists in their search after the most potent forms of compounds with therapeutic activity.…”

Section: Introductionmentioning

confidence: 99%

Scalable Synthesis and Supramolecular Assembly of trans‐A₂B₂ Porphyrins with Pendant Carboxylic Functional Groups

2017

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This article deals with facile synthesis of A2B2 porphyrins bearing carboxylate groups at 5,15‐ positions and different functional groups at 10,20‐ positions viz. 4‐iodophenyl (a), 4‐tert‐butylphenyl (b), 3,5‐dimethoxyphenyl (c) 3‐carboxyphenyl (d), 2‐thienyl (e) 4‐nitrophenyl (f), 4‐methoxy‐2,3,5,6‐tetrafluorophenyl (g) and 2‐pyrenyl (h) as single major component in scalable yields. It relates also to the supramolecular assembly modes of these species. The use of stoichiometric amounts of trifluoroacetic acid in condensation of 5‐(4‐methoxycarbonylphenyl)dipyrromethane and different aldehydes led to the formation of trans‐porphyrins as di‐esters (1 a‐1 h). These were transformed by hydrolysis to the corresponding di‐acids (2 a‐2 h). (1 a‐1 h) and (2 a‐2 h) were then core‐metalated to afford the corresponding metalloporphyrin species (3 a‐3 h) and (4 a‐4 h). The absorption and emission spectra of the free base (2 a‐2 h) and metallated porphyrins (4 a‐4 h) were found greatly influenced by the substituents at 10,20‐positions. SEM studies of solids deposited on surfaces from solution exhibited hydrogen‐bonded block‐shaped structures of 2 e and fibrous sheets of 2 f. Co‐crystallization of 2 a and 2 g with 4,4′‐bipyridyl yielded hetero‐molecular structures stabilized by both hydrogen O−H⋅⋅⋅N, and halogen N⋅⋅⋅I bonds in 2 a, and by O−H⋅⋅⋅N hydrogen bonds and C−F⋅⋅⋅π interactions in 2 g.

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“…2 O grande interesse pela química das RCs surgiu a partir da década de 1990 como uma vertente da química supramolecular e da engenharia de cristais. A química supramolecular busca entender as interações não covalentes envolvidas no processo de automontagem de estruturas supramoleculares, 3 enquanto que e a engenharia de cristais, utiliza esse mesmo princípio para entender o empacotamento das moléculas no estado sólido. 4…”

Section: Introductionunclassified

Coordination Networks: Design, Synthesis, Topology and Photophysical Properties

Ronconi

Martins²

2017

Rev. Virtual Quim.

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Coordination networks (CNs) are crystalline solids constructed via self-assembly of metal cations or metal clusters and organic ligands, forming one, two, or three-dimensional frameworks. The rational choice and assemble of both inorganic and organic counterparts can provide materials for optical applications, such as optical sensors, light-emitting devices, biomedical imaging and targeting devices and drug delivery systems. The aim of this Review is to provide an introductory overview on coordination networks with luminescent properties. Herein, we will give a description of the terms, definitions, topologies and classifications of CNs. Also, the photophysical processes and the origin of the luminescence in CNs are presented as well as some recent examples of the applications of these materials.

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Crystal engineering and IUCrJ

Abstract: Crystal engineering is discussed, along with its three key concepts: crystal packing; the design of solids; and physical and chemical properties.

Cited by 16 publications

References 5 publications

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

Scalable Synthesis and Supramolecular Assembly of trans‐A₂B₂ Porphyrins with Pendant Carboxylic Functional Groups

Coordination Networks: Design, Synthesis, Topology and Photophysical Properties

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Crystal engineering and IUCrJ

Abstract: Crystal engineering is discussed, along with its three key concepts: crystal packing; the design of solids; and physical and chemical properties.

Cited by 16 publications

References 5 publications

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

Halogen Bonding: A Halogen-Centered Noncovalent Interaction Yet to Be Understood

Scalable Synthesis and Supramolecular Assembly of trans‐A2B2 Porphyrins with Pendant Carboxylic Functional Groups

Coordination Networks: Design, Synthesis, Topology and Photophysical Properties

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Product

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Scalable Synthesis and Supramolecular Assembly of trans‐A₂B₂ Porphyrins with Pendant Carboxylic Functional Groups