A Tripyrrolylmethane-Based Macrobicyclic Triazacryptand: X-ray Structure, Size-Selective Anion Binding, and Fluoride-Ion-Mediated Proton–Deuterium Exchange Studies

Guchhait, Tapas; Mani, Ganesan; Schulzke, Carola; Anoop, Anakuthil

doi:10.1021/ic301546v

Cited by 24 publications

(20 citation statements)

References 96 publications

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“…Of particular interest to us is a burgeoning field of ingeniously designed, supramolecular fluoride receptors (21)(22)(23)(24)(25). The binding energies of these are just as large, and sometimes larger than that of the D4R box.…”

Section: Discussionmentioning

confidence: 99%

Eight-coordinate fluoride in a silicate double-four-ring

Goesten

Hoffmann

Bickelhaupt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Fluoride, nature's smallest anion, is capable of covalently coordinating to eight silicon atoms. The setting is a simple and common motif in zeolite chemistry: the box-shaped silicate double-four-ring (D4R). Fluoride seeks its center. It is the strain of box deformation that keeps fluoride in the middle of the box, and freezes what would be a transition state in its absence. Hypervalent bonding ensues. Fluoride's compactness works to its advantage in stabilizing the cage; chloride, bromide, and iodide do not bring about stabilization due to greater steric repulsion with the box frame. The combination of strain and hypervalent bonding, and the way they work in concert to yield this unusual case of multiple hypervalence, has potential for extension to a broader range of solidstate compounds.hat is the maximum number of atoms to which a maingroup element may bond? Four, one would normally think. But, hypervalence and delocalized bonding enlarge the upper range--no one bats an eyelid at silicon binding 6 ligands, and there exist cases of arguably 10-coordinate Si (1, 2). Much thinking on high coordination focuses on atomic or ionic radii, and packing considerations. Or, one can approach the problem from a quantum-chemical perspective. In this paper, we follow the latter course, and operate at the crossing point between molecular and extended systems. We explore how the upper bound for coordination number is determined by attractive and repulsive forces, adding in a factor of strain, associated with deforming a molecular cage that entraps an element in its center.The stage for this work is set by a simple and common motif in catalysis and separation: the silicate double-four-ring (D4R), one of the archetypal building blocks in large-pore zeolites. By use of relativistic density-functional theory (DFT) calculations and Kohn-Sham molecular orbital theory (3-6), we will see that within this box-like environment, fluoride coordinates, actually binds, to eight silicon atoms.

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Section: Discussionmentioning

confidence: 99%

Eight-coordinate fluoride in a silicate double-four-ring

Goesten

Hoffmann

Bickelhaupt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…In 2012, Guchhait et al 125 reported the tripyrrolylmethane-based triazacryptand 84 containing bridgehead carbon atoms. This cryptand as well as several acyclic molecules were obtained via a Mannich reaction involving a formylated tripyrrolylmethane, a secondary amine hydrochloride, and formaldehyde.…”

Section: Bicyclic Anion Receptorsmentioning

confidence: 99%

Supramolecular Chemistry of Anionic Dimers, Trimers, Tetramers, and Clusters

Sessler

2018

Chem

142

108

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Two or more anions constrained in close proximity within a single pocket are found in a number of natural systems but a less common motif in artificial systems. This review summarizes work on anion receptors capable of stabilizing anionic dimers, trimers, tetramers and clusters in a well-defined fashion. These systems may provide insights into the fundamental chemistry of anion-anion interactions and provide a guide for understanding in greater detail a number of biological and environmental processes, as well as key tenants of relevance to supramolecular chemistry, extraction, transport, crystal engineering, and the like. The primary goal of this review is to provide a general introduction into multi-anion recognition chemistry for the benefit of supramolecular and non-supramolecular chemists alike.

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“…These AEHBs can act as “bridges” between the complexed anions, further offsetting the unfavorable like-charge repulsive interactions that would be otherwise expected. Receptor-stabilized anion–anion complexes, including dimers, − trimers, − clusters, − and polymers, ,, have recently been reviewed independently by Sessler and Flood . It is noteworthy that, almost all of these reported examples involve homo-anion complexes, i.e., the cobound species consist of identical anions.…”

Section: Introductionmentioning

confidence: 99%

Constraining Homo- and Heteroanion Dimers in Ultraclose Proximity within a Self-Assembled Hexacationic Cage

Wang

Fang

et al. 2020

J. Am. Chem. Soc.

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A hexacationic cage 3 6+ was synthesized via hydrazone condensation in aqueous acid. Cage 3 6+ bears three biscationic arms, each of which contains four relatively acidic protons, including one NH and three CH protons. These hydrogen bond donors, as well as its intrinsic cationic nature, enable cage 3 6+ to encapsulate two anions concurrently within its cavity. The axial asymmetrical nature of the biscationic arms allow the cage to recognize two different anions in a selective manner, to encompass bound heteroanion dimers, such as Cl − •NO3 − and Cl − • Br − . Single crystal X-ray diffraction analyses reveal that in the solid state the two anions are constrained in ultraclose proximity within the cage; e.g., the Cl − •••Cl − and Cl − •••Br − distances are 3.2 and 2.9 Å, respectively, which are shorter than the sum of their van der Waals radii. Evidence consistent with the sequential binding of two identical or disparate anions in CD 3 CN is also presented.

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A Tripyrrolylmethane-Based Macrobicyclic Triazacryptand: X-ray Structure, Size-Selective Anion Binding, and Fluoride-Ion-Mediated Proton–Deuterium Exchange Studies

Cited by 24 publications

References 96 publications

Eight-coordinate fluoride in a silicate double-four-ring

Eight-coordinate fluoride in a silicate double-four-ring

Supramolecular Chemistry of Anionic Dimers, Trimers, Tetramers, and Clusters

Constraining Homo- and Heteroanion Dimers in Ultraclose Proximity within a Self-Assembled Hexacationic Cage

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