authors |
Mateus, P; Delgado, R; Brandao, P; Carvalho, S; Felix, V |
nationality |
International |
journal |
ORGANIC & BIOMOLECULAR CHEMISTRY |
keywords |
ANION COORDINATION CHEMISTRY; MOLECULAR-DYNAMICS; BINDING CONSTANTS; SPECIAL-ISSUE; FLUORIDE; MACROCYCLES; EQUILIBRIA; CYCLOPHANE; POLYAZA; WATER |
abstract |
A hexaamine cage was synthesised in good yield by a [2+3] Schiff-base condensation followed by sodium borohydride reduction to be used as a receptor for the selective binding of anionic species. The protonation constants of the receptor, as well as its association constants with Cl(-), I(-), NO(3)(-), AcO(-), ClO(4)(-), H(2)PO(4)(-), SO(4)(2-), SeO(4)(2-) and S(2)O(3)(2-) were determined by potentiometry at 298.2 +/- 0.1 K in H(2)O-MeOH (50 : 50 v/v) and at ionic strength 0.10 +/- 0.01 mol dm(-3) in KTsO. These studies revealed a remarkable selectivity for dianionic tetrahedral anions by the protonated receptor, with association constants ranging 5.03-5.30 log units for the dianionic species and 1.49-2.97 log units for monoanionic ones. Single crystal X-ray determination of [(H(6)xyl)(SO(4))(H(2)O)(6)](SO(4))(2)center dot 9.5H(2)O showed that one sulfate anion is encapsulated into the receptor cage sited between the two 2,4,6-triethylbenzene caps establishing three N-H center dot center dot center dot O hydrogen bonds with two adjacent N-H binding sites and additional O-H center dot center dot center dot O hydrogen bonding interactions with six water of crystallization molecules. Four water molecules of the (SO(4))(H(2)O)(6) cluster interact with [H(6)xyl](6+) through N-H center dot center dot center dot O hydrogen bonds. Molecular dynamics simulations (MD) carried out with SO(4)(2-) and Cl-anions in H(2)O-MeOH (50 : 50 v/v) allowed the full understanding of anion molecular recognition, the selectivity of the protonated receptor for SO(4)(2-) and the role played by the methanol and water solvent molecules. |
publisher |
ROYAL SOC CHEMISTRY |
issn |
1477-0520 |
year published |
2009 |
volume |
7 |
issue |
22 |
beginning page |
4661 |
ending page |
4673 |
digital object identifier (doi) |
10.1039/b912940e |
web of science category |
Chemistry, Organic |
subject category |
Chemistry |
unique article identifier |
WOS:000271432300014
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ciceco authors
impact metrics
journal analysis (jcr 2019):
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journal impact factor |
3.412 |
5 year journal impact factor |
3.134 |
category normalized journal impact factor percentile |
78.07 |
dimensions (citation analysis):
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altmetrics (social interaction):
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