Nanoscale Saturn Systems Based on C60/70 Bucky Ball and a Newly Designed [4]Cyclopara-1,2-diphenylethylene Hoop: A Strategy for Fullerene Encapsulation Release and Selective Recognition for C70

A new carbonaceous nanohoop, [4]cyclopara-1,2-diphenylethylene ([4]CPDPE, composed by four 1,2-diphenylethylene units linked via the para of the phenyls), is designed together with two rational synthesis paths being proposed. The Saturn-like host-guest systems formed with the [4]CPDPE nanoring and fullerene C_60/70 are explored using density functional theory calculations. The results evidence that the geometry mutual matching between [4]CPDPE and C_60/70 is perfect, and the [4]CPDPE⊃C_60/70 complexes could be formed spontaneously with high binding energies. Thermodynamic calculation results show that it essentially prefers to selectively recognize C₇₀ over its smaller cousin C₆₀. More interestingly, the [4]CPDPE nanoring could present the regular ring cylinder and the saddle shapes via configuration transformation between its all-trans form and all-cis form, so as to theoretically realize the fullerene encapsulation and release under photoirradiation. Furthermore, the 2:1 interaction structure ([4]CPDPE₂⊃Dimer-C₆₀) and properties are investigated. Additionally, the ultraviolet-visible (UV-vis) spectra are simulated, and host-guest noncovalent interaction (NCI) regions are investigated based on the electron density and reduced density gradient (RDG), which may be helpful for a deep understanding of the present designed systems in future.

Grape bunches of novel conjugated chain bonded fullerene oligomers: design of a potential electron trap carbonaceous molecular material

Developing π electron conjugated groups as covalent bonded bridges between fullerenes in their oligomers is key to optimizing and maximizing functions of the fullerene-based materials. In this work, a series of novel conjugated chain bonded fullerene C₆₀ oligomers (CBFOs) with a well-defined nano-architecture and "grape bunches" shapes are rationally designed and viably constructed based on fullerene-carbenes by means of DFT calculations. The results show that the presently designed CBFOs present a much better electron-accepting ability together with a much lower reorganization energy than the isolated fullerene C₆₀, and characterized as the potential ideal candidate for electron acceptors. The frontier molecular orbital and electron density analysis can well support the results of diabatic electron affinity (EA_a) and vertical electron affinity (EA_v) calculations. Moreover, these CBFOs exhibit strong absorption in the visible region but no obvious absorption in the ultraviolet region. In addition, the optical properties of the CBFOs and two dimensional structure are also simulated and explored theoretically. We hope that the present study would be helpful for developing covalent-bonded-fullerene based electron trap molecular materials, building blocks of nano-devices and nano-machinery applications.