Theoretical study of the influence of cation-π and anion-π interactions on some NMR data of borazine complexes

Supramolecular Luminescent Sensors

“…The anion-π interaction is a relatively newly investigated intermolecular phenomenon, especially compared to many of the aforementioned noncovalent interactions, , and there was initially some controversy around the legitimacy of such interactions, due to their counterintuitive nature, when they were first introduced. , A crystal structure demonstrating a close-range interaction between an anion and aromatic ring, reported in 2004, unambiguously proved that anion-π interactions exist in the solid state . Following that report, evidence of solution-state anion-π interactions was discovered via spectroscopic methods, and computational methods were used to obtain significantly improved understanding of such forces. , In contrast to the negative electron density that exists over an unsubstituted benzene ring, a significant region of positive electron density exists over aromatic rings with highly electronegative substituents, such as hexafluorobenzene. , This positive region of electron density can, in turn, bind to a broad variety of anions in a phenomenon termed an “anion-π interaction” (Figure ).…”

“…266 Following that report, evidence of solutionstate anion-π interactions was discovered via spectroscopic methods, 267 and computational methods were used to obtain significantly improved understanding of such forces. 268,269 In contrast to the negative electron density that exists over an unsubstituted benzene ring, a significant region of positive electron density exists over aromatic rings with highly electronegative substituents, such as hexafluorobenzene. 270,271 This positive region of electron density can, in turn, bind to a broad variety of anions in a phenomenon termed an "anion-π interaction" (Figure 6).…”

Tuning supramolecular aurophilic structures: the effect of counterion, positive charge and solvent

“…The largest 1 H-NMR downfield shift of H α and H β protons of 4 together with the smaller calculated coupling constants, are in agreement with a possible anion-π stacking disposition. 48 Thus, the triflate counterion could interact with the aromatic pyridyl ring giving a red-shifted and unresolved absorption band. These interactions may be favoured for this counterion possibility because of hydrogen bonding and could be the reason for the different package observed by SEM.…”

“…The highest recorded extinction coefficient is in agreement with the lack of formation of aggregates. Nevertheless, the profile is not completely understood since it resembles the spectra of the methylated 48 Thus, triflate counterion could interact with the aromatic pyridyl ring giving to a red-shifted and unresolved absorption band.…”

Boron Nitride-Doped Polyphenylenic Organogels

“…24,25 In this case, the moisture-sensitive nature of the chloroborazole units limits the manipulation of these materials under normal ambient conditions and consequently limits the versatility of their applications. The presence of BN (or BO) bonds proved to increase the affinity of the materials toward polar or charged species, 24,26 which is particularly important when engineering materials for gas adsorption/storage applications 24,25 and solid-state electrolytes (SSEs). 27,28 Moreover, the insertion of the thermally stable BN bonds has frequently led to the use of BN polymers as pre-ceramic/ hybrid materials.…”