Nature of Noncovalent Interactions in the [n]Cycloparaphenylene⊃C₇₀ (n = 10, 11, and 12) Host–Guest Complexes: A Theoretical Insight into the Shortest C₇₀–Carbon Nanotube Peapod

Abstract

The encapsulations of fullerene C 70 by carbon-nanorings are of great interest because, unlike the spheroidal C 60 , several distinct geometrical orientations are possible. Additionally, due to experimental difficulties, there is a great deal of opportunity for the computational efforts to deeply explore the intrinsic nature of π−π noncovalent interactions of the CPP carbon-nanoring⊃fullerene host−guest systems. In this paper, the structures and properties of the host−guest complexes formed with nanoring host [n]cycloparaphenylene (n =10, 11, and 12) ([n]CPP) and guest fullerene C 70 were detailed and explored by theoretical calculations. The results showed that three different kinds of quasi-inclusion configurations can be obtained for [10]CPP⊃C 70 and [11]CPP⊃C 70 host−guest complexes in which C 70 is lying, half-lying, and standing in the cavities of the hosts, respectively. However, there are only two kinds of stable configurations for [12]CPP⊃C 70 host−guest complexes in which C 70 is half-lying and standing in the cavities of the host [12]CPP, respectively. According to the relative values of the binding energies and thermodynamic information, the guest C 70 is apt to adopt lying, standing, and half-lying orientations in the cavities of [10]CPP, [11]CPP, and [12]CPP, respectively. The host−guest interaction regions were detected and visualized in real space based on the electron density and reduced density gradient (RDG). Additionally, IR, UV−visible−NIR, and 1 H NMR spectra of the hosts before and after the formations of the complexes have been simulated and discussed qualitatively, which may be helpful for further experimental investigations in the future.

Perspective: Found in translation: Quantum chemical tools for grasping non-covalent interactions

“…As a result, they capably identify the spatial extent and the underlying nature of interactions present in molecular systems and complexes. The relevance of NCI for studying large systems has been demonstrated on DNA, proteins, as well as nanotubes, 205,206 polymers, 207 and crystals under high pressure. 208 Moreover, this tool has also been used to explore reactivity, 114,184,209,210 dynamics, 191 and solvation 211 effects.…”

Dissecting the concave–convex π‐π interaction in corannulene and sumanene dimers: SAPT(DFT) analysis and performance of DFT dispersion‐corrected methods

“…Given the low polarity of most fullerenes, noncovalent interactions involving fullerenes are often dominated by dispersion, so most fullerene receptors are designed trying to maximize the fullerene‐receptor contact surface . In this way, different fullerene receptors have been proposed such as cycloparaphenylenes, porphyrins, and others . For this purpose, an interesting opportunity is to exploit the so‐called concave–convex π‐π interaction using buckybowls as receptors .…”

Charge transport and optical properties of the complexes of indigo wrapped over carbon nanotubes

“…9 The surface modified non-covalent complexes of CNTs are stabilized by van der Waals, electrostatic, p-p stacking, C-HÁ Á Áp and charge transfer interactions. [10][11][12][13][14][15] The developments made in the field of functionalized CNTs have been summarized in a review by Meng et al 16 Both experimental and theoretical studies have revealed that the complexes of single-walled carbon nanotubes (SWCNTs) possess enhanced electronic properties compared to free carbon nanotubes and can be used in electronic devices. 5,[17][18][19] The functionalization of CNTs alters their optical properties to a large extent as noticed in the CNT-squarylium complex in which the squarylium dye has been reported as a photosensitizer.…”