Three's company: co-crystallization of a self-assembled S4 metallacyclophane with two diastereomeric metallacycle intermediates

Lindquist, Nathan R.; Carter, Timothy G.; Cangelosi, Virginia M.; Zakharov, Lev N.; Johnson, Darren W.

doi:10.1039/b927034e

Cited by 22 publications

(16 citation statements)

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“…12 This unusual S 4 -symmetric coordination complex co-crystallizes with two cis- and trans- As 2 L tet Cl 2 intermediates in a single crystal. The S 4 -symmetry complex houses four As-π interactions per aryl ring (As-C aryl range: 3.24 and 3.45 Å) with the four As(III) metalloids pointing their lone pairs directly into the cavity, in an endo configuration.…”

Section: Pnictogen-π Interactions and “Supramolecular” Ligand Designmentioning

confidence: 91%

Ion−π Interactions in Ligand Design for Anions and Main Group Cations

2012

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Conspectus Interactions between ions and aromatic rings are now a mainstay in the field of supramolecular chemistry. The prototypical cation-π interaction, first characterized in the gas phase, is now well known as an important contributor to protein structure, enzyme function, and as a noncovalent force found in many synthetic systems. The complementary “anion-π interaction” – defined as an electrostatic attraction between an anion positioned over the centroid of an aromatic ring – has recently emerged as another reversible ion-π interaction in supramolecular systems. This type of interaction could offer new selectivity in binding poorly basic, strongly solvated anions and may also affect structure, biological function, and anion transport. This Account describes our group’s efforts in ion-π interactions in two areas. We first describe a series of self-assembled Group 15 (pnictogen)-thiolate complexes, all featuring prominent cation-π interactions between the trivalent pnictogen and an aromatic ring of the ligand. This structural feature appears to stabilize a variety of self-assembled dinuclear macrocycles, dinuclear M2L3 cryptand-analogs, and a tetranuclear As4L2 metallocyclophane. These complexes are all remarkably robust and feature intramolecular cation-π interactions, which suggest that these interactions could be an important feature in ligand design for the Group 15 elements. We also highlight our efforts to characterize the interaction between anions and electron-deficient aromatic rings in solution. Complementary crystallographic and computational studies suggest that off-center weak-σ interactions play the dominant role in stabilizing the anion-arene adducts unless an acidic CH bond is present to participate in favorable CH···anion hydrogen bonds. In solution the weak-σ complexes show downfield shifts of the proton resonances in their NMR spectra. With more polarizable anions such as bromide and iodide, we also observe anion binding by UV/Vis spectroscopy. Initial solution studies suggest these reversible interactions are weak in organic solvents, but the Hofmeister bias in anion binding could be mitigated, if not reversed, in the halides using these anion-π type interactions.

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Section: Pnictogen-π Interactions and “Supramolecular” Ligand Designmentioning

confidence: 91%

Ion−π Interactions in Ligand Design for Anions and Main Group Cations

2012

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“…Our method allows a route to tune the composition of such libraries to form specific, discrete assemblies that can then be isolated using recirculating gel permeation chromatography or crystallization, and ultimately captured by sulfur extrusion to provide a remarkable array of kinetically stable, diverse two-dimensional and three-dimensional (3D) cyclophanes (see experimental details in Supplementary Information ). The use of a pnictogen trichloride additive (for example, SbCl 3 ) is critical during the self-assembly step to encourage the formation of discrete disulfide species, perhaps serving an organizational role in bringing together multiple thiolates to form a discrete assembly through a combination of Sb-S and Sb-π interactions 28 29 30 31 32 33 34 . This two-step self-assembly and capture process appears to be general and occurs in high yield.…”

Section: Resultsmentioning

confidence: 99%

A facile route to old and new cyclophanes via self-assembly and capture

et al. 2016

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Cyclophanes are a venerable class of macrocyclic and/or cage compounds that often feature high strain, unusual conformations and quite surprising properties, many of which are legendary in physical organic chemistry. However, the discovery of new, diverse cyclophanes and derivatives has been hindered by syntheses that are traditionally low-yielding, requiring long reaction times, laborious purification steps and often extreme conditions. Herein, we demonstrate a new self-assembly route to a variety of discrete cyclic and caged disulfide structures, which can then be kinetically captured upon sulfur extrusion at room temperature to give a diversity of new thioether (hetera)cyclophanes in high yield. In addition to the synthesis of novel macrocycles (dimers through hexamers), this process provides an improved route to a known macrobicyclic trithiacyclophane. This technique also enables the facile isolation of a tetrahedral macrotricyclic tetrathiacyclophane in two steps at an ambient temperature.

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“…All the calculations were performed at the MP2/aug-cc-pVDZ level of theory, which can obtain reasonable results and has been used in several studies of noncovalent interactions (Lindquist et al, 2010;Chudzinski et al, 2011;Scheiner, 2013). Also results obtained from this method are found to be comparable with results obtained using the computationally more expensive CCSD(T) level of theory using a higher basis set (Hauchecorne & Herrebout, 2013;Nziko & Scheiner, 2016).…”

Section: Theoretical Methodsmentioning

confidence: 98%

Theoretical insights into the π-hole interactions in the complexes containing triphosphorus hydride (P₃H₃) and its derivatives

Wang

Zeng

et al. 2017

Acta Crystallogr B Struct Sci Cryst Eng Mater

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The π-hole of triphosphorus hydride (PH) and its derivatives ZX (Z = P, As; X = H, F, Cl, Br) was discovered and analyzed. MP2/aug-cc-pVDZ calculations were performed on the π-hole interactions in the HCN...ZX complexes and the mutual influence between π-hole interactions and the hydrogen bond in the HCN...HCN...ZX and HCN...ZX...HCN complexes studied. The π-hole interaction belongs to the typical closed-shell noncovalent interaction. The linear relationship was found between the most positive electrostatic potential of the π-hole (V) and the interaction energy. Moreover, the V of the π-hole was also found to be linearly correlated to the electrostatic energy term, indicating the important contribution of the electrostatic energy term to the π-hole interaction. There is positive cooperativity between the π-hole interaction and the hydrogen bond in the termolecular complexes. The π-hole interaction has a greater influence on the hydrogen bond than vice versa. The mutual enhancing effect between the π-hole interaction and the hydrogen bond in the HCN...HCN...ZX complexes is greater than that in the HCN...ZX...HCN complexes.

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Three's company: co-crystallization of a self-assembled S4 metallacyclophane with two diastereomeric metallacycle intermediates

Abstract: Three discrete supramolecular self-assembled arsenic(iii) complexes including an unusual S(4)-symmetric tetranuclear [As(4)L(2)Cl(4)] metallacyclophane and two diastereomeric cis/trans-[As(2)LCl(2)] metallacycle intermediates co-crystallize within a single crystal lattice.

Cited by 22 publications

References 41 publications

Ion−π Interactions in Ligand Design for Anions and Main Group Cations

Ion−π Interactions in Ligand Design for Anions and Main Group Cations

A facile route to old and new cyclophanes via self-assembly and capture

Theoretical insights into the π-hole interactions in the complexes containing triphosphorus hydride (P₃H₃) and its derivatives

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Three's company: co-crystallization of a self-assembled S4 metallacyclophane with two diastereomeric metallacycle intermediates

Abstract: Three discrete supramolecular self-assembled arsenic(iii) complexes including an unusual S(4)-symmetric tetranuclear [As(4)L(2)Cl(4)] metallacyclophane and two diastereomeric cis/trans-[As(2)LCl(2)] metallacycle intermediates co-crystallize within a single crystal lattice.

Cited by 22 publications

References 41 publications

Ion−π Interactions in Ligand Design for Anions and Main Group Cations

Ion−π Interactions in Ligand Design for Anions and Main Group Cations

A facile route to old and new cyclophanes via self-assembly and capture

Theoretical insights into the π-hole interactions in the complexes containing triphosphorus hydride (P3H3) and its derivatives

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Theoretical insights into the π-hole interactions in the complexes containing triphosphorus hydride (P₃H₃) and its derivatives