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A systematic structural study of halogen bonding versus hydrogen bonding within competitive supramolecular systems.

Aakeröy CB, Spartz CL, Dembowski S, Dwyre S, Desper J - IUCrJ (2015)

Bottom Line: As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system.The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values.It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Kansas State University , Manhattan, KS 66506, USA.

ABSTRACT
As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system. As hydrogen and halogen bonds have several fundamental features in common, it is often difficult to predict which will be the primary interaction in a supramolecular system, especially as they have comparable strength and geometric requirements. To address this challenge, a series of molecules containing both hydrogen- and halogen-bond donors were co-crystallized with various monotopic, ditopic symmetric and ditopic asymmetric acceptor molecules. The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values. It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

No MeSH data available.


The main interaction in the crystal structure of IF4-OX – 3 (A = acceptor, H = hydrogen-bond donor).
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fig8: The main interaction in the crystal structure of IF4-OX – 3 (A = acceptor, H = hydrogen-bond donor).

Mentions: Five crystal structures were obtained with monotopic acceptors and the predominant outcome (4/5) was a co-crystal in a 1:1 stoichiometry assembled from hydrogen bonds with no discernable contributions from halogen bonds (Fig. 7 ▸). Three of the four representatives in this group (IF4-OX – 3, Br-OX – 5 and Br-COOH – 3) displayed near-identical behavior (as postulated in Fig. 1 ▸, bottom left) with the two reactants held together by near-linear hydrogen bonds resulting in 1:1 dimeric species with no evidence of proton transfer, Fig. 8 ▸.


A systematic structural study of halogen bonding versus hydrogen bonding within competitive supramolecular systems.

Aakeröy CB, Spartz CL, Dembowski S, Dwyre S, Desper J - IUCrJ (2015)

The main interaction in the crystal structure of IF4-OX – 3 (A = acceptor, H = hydrogen-bond donor).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4547818&req=5

fig8: The main interaction in the crystal structure of IF4-OX – 3 (A = acceptor, H = hydrogen-bond donor).
Mentions: Five crystal structures were obtained with monotopic acceptors and the predominant outcome (4/5) was a co-crystal in a 1:1 stoichiometry assembled from hydrogen bonds with no discernable contributions from halogen bonds (Fig. 7 ▸). Three of the four representatives in this group (IF4-OX – 3, Br-OX – 5 and Br-COOH – 3) displayed near-identical behavior (as postulated in Fig. 1 ▸, bottom left) with the two reactants held together by near-linear hydrogen bonds resulting in 1:1 dimeric species with no evidence of proton transfer, Fig. 8 ▸.

Bottom Line: As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system.The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values.It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Kansas State University , Manhattan, KS 66506, USA.

ABSTRACT
As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system. As hydrogen and halogen bonds have several fundamental features in common, it is often difficult to predict which will be the primary interaction in a supramolecular system, especially as they have comparable strength and geometric requirements. To address this challenge, a series of molecules containing both hydrogen- and halogen-bond donors were co-crystallized with various monotopic, ditopic symmetric and ditopic asymmetric acceptor molecules. The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values. It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

No MeSH data available.