Strengthening N⋯X halogen bonding via nitrogen substitution in the aromatic framework of halogen-substituted arylpyrazinamides

Khavasi, Hamid Reza; Hosseini, Mahdieh; Tehrani, Alireza Azhdari; Naderi, Soheila

doi:10.1039/c3ce41856a

Cited by 15 publications

(16 citation statements)

References 35 publications

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“…Comparing the C–I stretching frequency of NMI-Py+TEG-I (1482 cm –1 ) with that of TEG-I (1485 cm –1 ) in water (Figure S9) confirmed the presence of X-bonding between NMI-Py and TEG-I in the construction of the supra-π-amphiphile. DFT optimized geometry of NMI-Py+TEG-I monomer revealed a N–I halogen bonding distance of 2.9 Å (Figure S10), which is comparable with the reported crystal structure data for N–I based halogen bonds . Unlike fibrillar morphology of NMI-Py+PEG-I , TEM images (Figure a, Figure S11) from an aqueous solution of NMI-Py+TEG-I revealed nearly spherical hollow structures, reminiscent of vesicle-like morphology with diameter in the range of 200–400 nm.…”

Section: Resultssupporting

confidence: 80%

“…DFT optimized geometry of NMI-Py+TEG-I monomer revealed a N−I halogen bonding distance of 2.9 Å (Figure S10), which is comparable with the reported crystal structure data for N−I based halogen bonds. 50 Unlike fibrillar morphology of NMI-Py +PEG-I, TEM images (Figure 2a, Figure S11) from an aqueous solution of NMI-Py+TEG-I revealed nearly spherical hollow structures, reminiscent of vesicle-like morphology with diameter in the range of 200−400 nm. The particle size (D ∼ 350 nm) from variable-temperature (VT) dynamic light scattering (DLS) experiment (Figure S12) corroborated with the TEM results.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

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Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles

et al. 2020

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Supra-amphiphiles constituted of noncovalent bonds have emerged as attractive systems for fabrication of stimuli-responsive self-assembled nanostructures. A unique supramolecular strategy utilizing halogen (X)-bonding interaction has been demonstrated for constructing emissive supra-π-amphiphiles in water from a hydrophobic pyridyl functionalized naphthalene monoimide (NMI-Py) based X-bond acceptor and hydrophilic iodotetrafluorophenyl functionalized polyethylene glycol (PEG-I) or triethylene glycol (TEG-I) based X-bond donors, while their luminescent higher ordered assemblies were governed by orthogonal dipole−dipole interaction and π-stacking of the NMI-Py fluorophore as probed by SCXRD and DFT calculations. Control molecules lacking iodotetrafluorophenyl moiety at the polyethylene glycol chain end failed to create any defined morphology from the NMI-Py, suggesting X-bonding is prerequisite for the nanostructure formation. Variation in the chain length of the X-bond donors leads to different morphologies (fiber vs vesicle) for PEG-I and TEG-I. Acid triggered denaturing of the X-bonds caused pH responsive disassembly of the thermally robust nanostructures. This strategy paves the way for facile fabrication of structurally diverse smart and adaptive luminescent functional materials with tunable morphology.

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Section: Resultssupporting

confidence: 80%

Section: ■ Results and Discussionmentioning

confidence: 96%

Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles

et al. 2020

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“…The alternative approach is to increase the electron density of the halogen bond acceptor by the introduction of electron donating substituents. 63 A stronger halogen bond is often presumed to be reflected by a shorter distance between the halogen bond donor and the acceptor. 48 , 64 , 65 Computational studies revealed that the Hammett substituent constants of pyridine-based halogen bond acceptors correlate to the strength of their halogen bond.…”

Section: Resultsmentioning

confidence: 99%

Substituent Effects on the [N–I–N]⁺ Halogen Bond

et al. 2016

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We have investigated the influence of electron density on the three-center [N–I–N]+ halogen bond. A series of [bis(pyridine)iodine]+ and [1,2-bis((pyridine-2-ylethynyl)benzene)iodine]+ BF4– complexes substituted with electron withdrawing and donating functionalities in the para-position of their pyridine nitrogen were synthesized and studied by spectroscopic and computational methods. The systematic change of electron density of the pyridine nitrogens upon alteration of the para-substituent (NO2, CF3, H, F, Me, OMe, NMe2) was confirmed by 15N NMR and by computation of the natural atomic population and the π electron population of the nitrogen atoms. Formation of the [N–I–N]+ halogen bond resulted in >100 ppm 15N NMR coordination shifts. Substituent effects on the 15N NMR chemical shift are governed by the π population rather than the total electron population at the nitrogens. Isotopic perturbation of equilibrium NMR studies along with computation on the DFT level indicate that all studied systems possess static, symmetric [N–I–N]+ halogen bonds, independent of their electron density. This was further confirmed by single crystal X-ray diffraction data of 4-substituted [bis(pyridine)iodine]+ complexes. An increased electron density of the halogen bond acceptor stabilizes the [N···I···N]+ bond, whereas electron deficiency reduces the stability of the complexes, as demonstrated by UV-kinetics and computation. In contrast, the N–I bond length is virtually unaffected by changes of the electron density. The understanding of electronic effects on the [N–X–N]+ halogen bond is expected to provide a useful handle for the modulation of the reactivity of [bis(pyridine)halogen]+-type synthetic reagents.

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“…A comparison of the structures of N-(4-halophenyl)pyrazine-2-carboxamide and N-(5-halo-2-pyridinyl)pyrazine-2carboxamide suggests that the intramolecular N-HÁ Á ÁN(py) (py is pyridine) hydrogen-bonding interaction generates better coplanarity between the aromatic rings (Khavasi et al, 2014). In 6-fluoro-3-hydroxypyrazine-2-carboxamide, intramolecular O-HÁ Á ÁO hydrogen bonding, in addition to preventing keto-enol tautomerism of the hydroxy group, forms a six-membered ring motif.…”

Section: Pyrazine Derivatives and Their Available Donoracceptor Sitesmentioning

confidence: 99%

A survey of interactions in crystal structures of pyrazine-based compounds

Taghipour

Mirzaei

2019

Acta Crystallogr C

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The important role of pyrazine (pz) and its derivatives in fields such as biochemistry and pharmacology, as well as in the study of magnetic properties, is surveyed. Recognition of these properties without extensive investigations into their structural properties is not possible. This review summarizes interactions that exist between these organic compounds by themselves in the solid state, as well as those in coordination polymers with metal ions and in polyoxometalatebased hybrids. Complexes based on pyrazine ligands can generate metal-organic framework (MOF) structures that bind polyoxometalates (POMs) through covalent and noncovalent interactions. Some biological and magnetic properties involving these compounds are considered and the effect of hydrogen bonding on their supramolecular architectures is highlighted. feature articles 232 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds Acta Cryst. (2019). C75, 231-247 feature articles 234 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds Acta Cryst. (2019). C75, 231-247 feature articles Acta Cryst. (2019). C75, 231-247 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds 237 Figure 9Structure of [Cu 2 (PZOAPZ-H)Br 3 (H 2 O) 2 ]. Reproduced from Grove et al. (2004) with permission. feature articles Acta Cryst. (2019). C75, 231-247 Taghipour and Mirzaei A survey of interactions of pyrazine-based compounds 245

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Strengthening N⋯X halogen bonding via nitrogen substitution in the aromatic framework of halogen-substituted arylpyrazinamides

Abstract: The importance of N⋯X halogen bonding in a series of N-(5-halo-2-pyridinyl)pyrazine-2-carboxamides has been investigated by different methods.

Cited by 15 publications

References 35 publications

Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles

Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles

Substituent Effects on the [N–I–N]⁺ Halogen Bond

A survey of interactions in crystal structures of pyrazine-based compounds

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Strengthening N⋯X halogen bonding via nitrogen substitution in the aromatic framework of halogen-substituted arylpyrazinamides

Abstract: The importance of N⋯X halogen bonding in a series of N-(5-halo-2-pyridinyl)pyrazine-2-carboxamides has been investigated by different methods.

Cited by 15 publications

References 35 publications

Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles

Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles

Substituent Effects on the [N–I–N]+ Halogen Bond

A survey of interactions in crystal structures of pyrazine-based compounds

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Substituent Effects on the [N–I–N]⁺ Halogen Bond