A new hexaaminomacrocycle for ditopic binding of bromide

Gibson, Don; Dey, Kalpana R.; Fronczek, Frank R.; Hossain, Md. Alamgir

doi:10.1016/j.tetlet.2009.09.041

Cited by 12 publications

(11 citation statements)

References 28 publications

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“…Although, the attachment of dansyl groups makes the secondary amines unavailable for protonation, the ligand binds an anion strongly. As reported previously, the parent ligand 1 in its tertraprotonated form was found to show moderate binding affinity ( K = 500 M −1 ) for bromide in CDCl 3 , that was determined by 1 H NMR titrations 20. In the present case, the observed high binding constants measured at much dilute conditions (1 × 10 −6 M compared with 5 × 10 −3 M) can be attributed to the decreased salt effect25 as well as the involvement of CH…anion interactions 26,27.…”

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confidence: 72%

“…Herein, we use a simple strategy of making an anion sensor L using a macrocycle and dansyl groups as fluorophore units. We choose a macrocyclic precursor ligand 1 consisting of both secondary and tertiary amines, which by itself is an effective anion receptor 20. This particular combination of two different amines allows the ligand to add dansyl groups at the secondary amines leaving two tertiary amines unreacted that are available for protonation.…”

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confidence: 99%

“…The synthesis of precursor 1 was accomplished from the reaction of N -methyl-2,2'-diaminodiethylamine with terephthaldehyde in CH 3 OH under high dilution condensation and the subsequent reduction of the resulting imine with NaBH 4 (Scheme 1) following the procedure previously reported by us 20. The reaction of neutral 1 with four equivalents of dansyl chloride in the presence of K 2 CO 3 in CH 3 CN afforded the target chemosensor L .…”

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confidence: 99%

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Rational design of a macrocycle-based chemosensor for anions

Dey

Wong

Hossain

2010

Tetrahedron Letters

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A macrocyclic-based fluorescence chemosensor has been designed and synthesized from the reaction of dansyl chloride and a hexaaminomacrocycle containing four secondary and two tertiary amines. The new chemosensor has been examined for its binding ability toward phosphate, sulfate, nitrate, iodide, bromide, chloride, and fluoride by fluorescence spectroscopy in DMSO. The results indicate that the compound binds each of the anions with a 1:1 stoichiometry, showing high affinity for the oxoanions, chloride and iodide with the binding constants up to four orders of magnitude. Ab initio calculations based on density functional theory (DFT) suggest that the ligand is deformed in order to encapsulate an anion, and each anion, except fluoride, is bonded to the macrocycle through two NH…X− and four CH…X− interactions.

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confidence: 72%

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confidence: 99%

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Rational design of a macrocycle-based chemosensor for anions

Dey

Wong

Hossain

2010

Tetrahedron Letters

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“…The obtained 1:1 binding mode, however, is not consistent with the results observed in crystal structure. This inconsistency is most likely due to the effect of polar solvent used in the titration which tends to highly solvate the ligand, resulting in reduced populations of binding sites 14,16. We were, therefore, interested in examining the binding studies in a non-polar solvent like CDCl 3 .…”

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Charge-Assisted Encapsulation of Two Chlorides by a Hexaprotonated Azamacrocycle

Hossain

Saeed

Fronczek

et al. 2010

Crystal Growth & Design

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A chloride complex of a hexaprotonated azamacrocycle has been isolated, and its structure has been determined by X-ray crystallography showing two encapsulated chloride anions in the cavity. The two internal guests are coordinated at two binding sites on the opposite side of the macrocycle through trigonal recognition by hydrogen-bonding interactions. The other four chlorides are located outside the cavity, each with a single hydrogen bond from secondary amines. Ab initio calculations based on density functional theory (DFT) suggest that the encapsulation of two chlorides inside the cavity leads to a significant charge transfer from the anions to the protonated amines.

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“…In an effort to achieve selective anion receptors, we decided to examine the anion binding ability of L that was synthesized from the condensation of N -methyl-2,2′-diaminodiethylamine and terephthalaldehyde in methanol followed by the reduction with NaBH 4 17. X-Ray quality crystals of the sulfate complex were grown from a slow evaporation of the solution of L in water in presence of H 2 SO 4 at pH 2.0.…”

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Encapsulation and selective recognition of sulfate anion in an azamacrocycle in water

et al. 2010

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Structural characterization of a sulfate complex with an azamacrocycle suggests that one sulfate is encapsulated in the macrocyclic cavity with eight hydrogen bonds; a significant selectivity of the host was observed for sulfate over halides, nitrate and perchlorate as evaluated by 1 H NMR studies in water.Sulfate is present in the biological system and plays a crucial role in many biochemical processes, 1 such as in biosynthesis 2 and sulfate binding proteins. 3 Sulfate is also a known inorganic pollutant in the environment. 4 For example, contamination of the Hanford nuclear waste site by this anion has been a matter of increased concern, hampering the vitrification process. 5 However, as compared to other oxoanions, such as phosphate and nitrate, this anion has been less studied with synthetic hosts. 6 Therefore, the design of suitable hosts for selective recognition of sulfate remains a challenge in the area of anion binding chemistry. 7 Encapsulated sulfate was crystallographically characterized in self-assembled metal-organic cage hosts, polyamides, 8 ureas 9 or indoles. 10 In these cases, an encapsulation occurred within the crystal lattices formed by a host matrix or between hosts. Based on the theoretical † Electronic supplementary information (ESI) available: One crystallographic data in CIF format, the synthetic procedure in pdf format. CCDC 777812. For ESI and crystallographic data in CIF or other electronic format see

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A new hexaaminomacrocycle for ditopic binding of bromide

Cited by 12 publications

References 28 publications

Rational design of a macrocycle-based chemosensor for anions

Rational design of a macrocycle-based chemosensor for anions

Charge-Assisted Encapsulation of Two Chlorides by a Hexaprotonated Azamacrocycle

Encapsulation and selective recognition of sulfate anion in an azamacrocycle in water

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