Anion Influence on the Packing of 1,3-Bis(4-Ethynyl-3-Iodopyridinium)-Benzene Halogen Bond Receptors

Decato, Daniel A.; Riel, Asia Marie S.; Berryman, Orion B.

doi:10.3390/cryst9100522

Cited by 5 publications

(4 citation statements)

References 63 publications

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“…Aromatic CI··N XBs have been the subject of a slightly more extensive study, for example, with regard to azobenzenes, 4-iodotetrafluorophenylalanine, C 6 F 5 I, or the architecture of the crystals formed between ortho-, meta-, or para-diiodotetrafluorobenzene and 2,7-dipyridylfluorene . Also, the ability of these aromatic C–I groups to engage in strong XBs forms the basis of an innovative class of highly selective anion-binding agents currently under development. − Unsubstituted iodobenzene is capable of forming a CI··N XB with quinuclidine, with a R(C··N) separation of 2.93 Å.…”

Section: Discussionmentioning

confidence: 99%

Proximity Effects of Substituents on Halogen Bond Strength

Lapp

Scheiner

2021

J. Phys. Chem. A

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It is well known that the presence of an electron-withdrawing substituent (EWS) placed near the halogen (X) atom on a Lewis acid molecule amplifies the ability of this unit to engage in a halogen bond with a base. Quantum calculations are applied to examine how quickly these effects fade as the EWS is moved further and further from the X atom. Conjugated alkene and alkyne chains of varying lengths with a terminal C−I first facilitate analysis as to how the number of these multiple bonds affects the strength of CI••N XB to NH 3 . Then, electron-withdrawing F and CN substituents are placed on the opposite end of the chain, and their effects on the XB properties are monitored as a function of their distance from I. These same EWSs are added to the ortho, meta, and para positions of aromatic iodobenzene. It is found that the XB grows in strength as more triple bonds are added to the alkyne, but there is little change caused by elongating an alkene. The cyano group has a much stronger effect than does F. While F strengthens the XB, its effects are quickly attenuated as it is moved further from I. The consequences of CN substitution are stronger and extend over a longer distance. Placement of an EWS on the phenyl ring diminishes with distance: o > m > p, and the effects of disubstitution are nearly additive. These trends apply not only to energetics but also to geometries, properties of the wave function, σ-hole depth, and NMR shielding.

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Section: Discussionmentioning

confidence: 99%

Proximity Effects of Substituents on Halogen Bond Strength

Lapp

Scheiner

2021

J. Phys. Chem. A

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“…Selective binding of anions is one example. Whereas some of the earlier ditopic receptors made use of H-bonds, more recent work has taken advantage of various sorts of σ-hole bonds to improve on the binding strength and selectivity. − The σ-hole bonds have grown in terms of their impact on synthesis and catalysis, − crystal and polymer design, − ionic liquids, biological activity, − chromatography, and electronic materials …”

Section: Introductionmentioning

confidence: 99%

Dissection of the Origin of π-Holes and the Noncovalent Bonds in Which They Engage

Scheiner

2021

J. Phys. Chem. A

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Accompanying the rapidly growing list of σ-hole bonds has come the acknowledgment of parallel sorts of noncovalent bonds which owe their stability in large part to a deficiency of electron density in the area above the molecular plane, known as a π-hole. The origins of these π-holes are probed for a wide series of molecules, comprising halogen, chalcogen, pnicogen, tetrel, aerogen, and spodium bonds. Much like in the case of their σ-hole counterparts, formation of the internal covalent π-bond in the Lewis acid molecule pulls density toward the bond midpoint and away from its extremities. This depletion of density above the central atom is amplified by an electron-withdrawing substituent. At the same time, the amplitude of the π*-orbital is enhanced in the region of the density-depleted π-hole, facilitating a better overlap with the nucleophile’s lone pair orbital and a stabilizing n → π* charge transfer. The presence of lone pairs on the central atom acts to attenuate the π-hole and shift its position somewhat, resulting in an overall weakening of the π-hole bond. There is a tendency for π-hole bonds to include a higher fraction of induction energy than σ-bonds with proportionately smaller electrostatic and dispersion components, but this distinction is less a product of the σ- or π-character and more a function of the overall bond strength.

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“…There are many papers related to charge transfer cocrystals published in several special issues of the journal Crystals covering different aspects, including donor-acceptor packing type of co-crystals [43,44], hydrogen-bonded co-crystals [45,46], conducting and superconducting co-crystals [47,48], etc. However, it is still worth discussing the role of stoichiometry between donor and acceptor in co-crystals.…”

Section: Of 18mentioning

confidence: 99%

The Stoichiometry of TCNQ-Based Organic Charge-Transfer Cocrystals

Gao

Zhai

et al. 2020

Crystals

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Organic charge-transfer cocrystals (CTCs) have attracted significant research attention due to their wide range of potential applications in organic optoelectronic devices, organic magnetic devices, organic energy devices, pharmaceutical industry, etc. The physical properties of organic charge transfer cocrystals can be tuned not only by changing the donor and acceptor molecules, but also by varying the stoichiometry between the donor and the acceptor. However, the importance of the stoichiometry on tuning the properties of CTCs has still been underestimated. In this review, single-crystal growth methods of organic CTCs with different stoichiometries are first introduced, and their physical properties, including the degree of charge transfer, electrical conductivity, and field-effect mobility, are then discussed. Finally, a perspective of this research direction is provided to give the readers a general understanding of the concept.

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Anion Influence on the Packing of 1,3-Bis(4-Ethynyl-3-Iodopyridinium)-Benzene Halogen Bond Receptors

Cited by 5 publications

References 63 publications

Proximity Effects of Substituents on Halogen Bond Strength

Proximity Effects of Substituents on Halogen Bond Strength

Dissection of the Origin of π-Holes and the Noncovalent Bonds in Which They Engage

The Stoichiometry of TCNQ-Based Organic Charge-Transfer Cocrystals

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