Halogen Bonds (N---I) at Work: Supramolecular Catemeric Architectures of 2,7-Dipyridylfluorene with ortho-, meta-, or para-Diiodotetrafluorobenzene Isomers

Grosu, Ioana Georgeta; Pop, Lucian Cristian; Miclăuş, Maria; Hădade, Niculina D.; Terec, Anamaria; Bende, Attila; Socaci, Crina; Barboiu, Mihail; Grosu, Ion

doi:10.1021/acs.cgd.0c00205

Cited by 17 publications

(13 citation statements)

References 66 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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“…[44] Quantum chemistry calculations Calculations were carried out to estimate the contributions of the different fragments of the lattice to the stabilization of the crystal structures. [55] The selected interaction units and their geometry parameters for calculating interaction energies were extracted from the crystal structure data, as shown in Figures 1-3 and S3-S4. The results are listed in Table S2.…”

Section: Ternary Per@ditfb • Bpno Cocrystalmentioning

confidence: 99%

Ternary Cocrystals with Large Soft Cavities: A 1,4‐diiodotetrafluorobenzene (DITFB)⋅4‐Biphenylpyridine N‐oxide (BPNO) Host Assembled by Inclusion of Planar Aromatic Guests

et al. 2021

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A large soft-cavity host composed of 1,4-diiodotetrafluorobenzene (DITFB) and 4-biphenylpyridine N-oxide (BPNO) is assembled under the mediation of a planar aromatic guest molecule (pyrene or perylene) through CÀ I••• À OÀ N + halogen bonds and π-hole•••π bonds. Single-crystal X-ray diffraction reveals that guest molecules can be completely encapsulated in the four-layer host cavity to assemble ternary host-guest cocrystals; namely, Pyr@DITFB • BPNO and Per@DITFB • BPNO. The luminescence of these ternary cocrystals originates from their discrete guest molecules, which exhibit pure-blue and yellow emissions, respectively, that are localized at 425 nm and in the range of 485 to 578 nm, respectively. In addition, the contribution of different fragments to the stabilization of the crystal structure is estimated by computational chemistry. These cocrystals have significant potential for use in optical applications or materials, such as photonics or organic light-emitting diodes, respectively, that require to avoid the aggregation between luminophores.

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“…In the context of our previous experience with correlating experimental solution and solid-state structural data with computational studies (Grosu et al, 2017;Grosu et al, 2020), we were interested in elaborating a computational work to access information about the behavior of both the ether oxime units and the bridge in the racemization process and how complexation of our ethyleneoxide bridged banisters (1-3) with different alkali metal ions (Li + , Na + , K + ) and diethylammonium ion as organic cation would influence the stability of the enantiomers, aiming to increase the barrier to rotation of these atropisomers. Moreover, as we managed to grow single crystals of 4, a thorough investigation of the crystal molecular structure and corroboration of calculations based on the solid-state data are expected to offer insight into the role of various contacts to the stabilization of the supramolecular architecture.…”

Section: Introductionmentioning

confidence: 99%

Solid-State and Theoretical Investigations of Some Banister-Type Macrocycles with 2,2’-Aldoxime-1,1’-Biphenyl Units

et al. 2021

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In the context of helical chirality, bridging of biphenyl units leads to banister-type compounds and the stability of the resulted atropisomers may increase dramatically if suitable changes are performed in the linker unit that coils around the biphenyl moiety. A rigorous density functional theory (DFT) study was conducted for macrocycles containing rigid oxime ether segments connected to the biphenyl backbone in order to determine how the rotation barriers are influenced by the presence of either a flexible oligoethyleneoxide or a more rigid m–xylylene component in the macrocycle. The calculated values for the racemization barrier were in good agreement with those obtained experimentally and confirm the benefit of introducing a more rigid unit in the macrocycle on the stability of atropisomers. Solid-state data were obtained and computed data were used to assess the contribution brought by supramolecular associations observed in the lattice to the stabilization of the crystal structure. Beside introducing rigidity in the linker, complexation of flexible macrocycles with alkali metal ions is also contributing to the stability of atropisomers, leading to values for the racemization barrier matching that of the rigid macrocycle. Using diethylammonium cation as guest for the macrocycle, a spectacular increase in the barrier to rotation was observed for the resulted pseudo[2]rotaxane.

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Halogen Bonds (N---I) at Work: Supramolecular Catemeric Architectures of 2,7-Dipyridylfluorene with ortho-, meta-, or para-Diiodotetrafluorobenzene Isomers

Cited by 17 publications

References 66 publications

Proximity Effects of Substituents on Halogen Bond Strength

Proximity Effects of Substituents on Halogen Bond Strength

Ternary Cocrystals with Large Soft Cavities: A 1,4‐diiodotetrafluorobenzene (DITFB)⋅4‐Biphenylpyridine N‐oxide (BPNO) Host Assembled by Inclusion of Planar Aromatic Guests

Solid-State and Theoretical Investigations of Some Banister-Type Macrocycles with 2,2’-Aldoxime-1,1’-Biphenyl Units

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