Impact of the Chirality and Curvature of Carbon Nanostructures on Their Interaction with Aromatics and Amino Acids

Abstract

Understanding noncovalent interactions on the surfaces of carbon nanostructures (CNSs) is of fundamental importance and also has implications in nano- and biotechnology. The interactions of aromatic compounds such as benzene, naphthalene, and aromatic amino acids with CNSs of varying diameter, chirality, and curvature were systematically explored by using density functional theory. Planar graphene exhibits stronger binding affinity than curved carbon nanotubes (CNTs), whereas zigzag CNTs appear to show stronger binding affinity than armchair CNTs. For hydrocarbons, there exist two competing modes, namely, π-π stacking interactions and CH···π interactions, which bring the aromatic motifs into parallel and perpendicular dispositions with respect to the CNSs, respectively. Our results reveal that π-π stacking interactions override CH···π interactions in such cases. However, in the case of aromatic amino acids, π-π interactions can exist simultaneously along with a range of other interactions, including CH···π. The polarizability and HOMO energy of the CNSs were found to be the key factors that determine the binding energies. The HOMO-LUMO energy gaps of the CNSs were found to be undisturbed by the noncovalent functionalization of the aromatic molecules.

Protein functionalized carbon nanomaterials for biomedical applications

“…The relative alignment of the carbon atoms along the SWNT lattice is known to influence their electronic properties and interfacial interactions, hence it influences protein conjugates and the eventual application of the SWNT-protein conjugate. Researchers have begun to undertake the task of examining the role of carbon nanotube chirality, curvature, and structure in its non-covalent interactions with the nanotube corona and the protein corona [152]. In addition, nanotoxicity concerns need to be addressed when aiming for applications involving biological cells, tissues, or animal models [153,154].…”

Functional molecules and materials by π‐Interaction based quantum theoretical design

“…[90] They also mentioned that the interaction energy of aromatic amino acids such as Phe, Tyr, Trp, and His (at the M06-2X/6-311G**//ONIOM level) on the surfaces of carbon nanostructures is controlled by interplay between p-p stacking and CH-p interactions which is stronger in planar graphene than curved CNTs. [90] Sensors based on noncovalent p-interactions recognize anions via three modes of interactions: (1) r-interaction with partially positively-charged CH or NH of arenes (C-H 1 ÁÁÁX 2 and (2) anion-p interaction between anion and arenes with large, positive quadrupole moment (Q zz ), [21] and (3) C-H hydrogen bond with carbon atom of electron-deficient arene (Lewis acidic aromatic rings). [67,91] The r/p-anion interactions can be significantly enhanced by increasing the magnitude of electron deficiency in arene.…”

Saturated vs. unsaturated hydrocarbon interactions with carbon nanostructures

“…The noncovalent interactions of CNSs such as cation−π, π − π, and CH···π with various metal ions, bio-molecules, and small molecules have been analyzed in several theoretical studies (Umadevi and Sastry, 2011a,b, 2012, 2013, 2014). Noncovalent interactions are ubiquitous and central in several areas of contemporary scientific interest.…”

“…The extended π-network in the 2D graphene is the basic building block for CNSs of various dimensions, for instance 3D graphite, which is formed from the stacked layers of graphene, 1D CNTs which is basically the rolled graphene sheet and the 0D fullerene is formed by wrapping the graphene sheet. We have shown by a series of studies that the planar graphene shows stronger binding affinity than the curved CNTs toward noncovalent interactions (Umadevi and Sastry, 2011b, 2013, 2014). Besides, comparing and contrasting the binding affinity of CNTs of different chirality and curvature is interesting in its own right.…”