Comparative study of diradical characters and third‐order nonlinear optical properties of linear/cyclic acenes versus phenylenes

Abstract

A long‐range corrected spin‐unrestricted density functional theory (LC‐UDFT) approach has been used to investigate the diradical character (yi) and third‐order nonlinear optical properties of linear/cyclic [N]acenes and [N]phenylenes in their ground states, where N is the number of benzene rings in each linear and cyclic configuration. It has been found that linear and cyclic acenes with N = 5–10 show singlet diradical characters, while linear and cyclic phenylenes with equivalent number of benzene rings have closed‐shell configurations. The amplitudes of third‐order nonlinear optical polarizability (γzzzz) for open‐shell linear/cyclic acenes are larger especially in intermediate range of diradical character than those of closed‐shell phenylene counterparts. For example, the γzzzz values of [5]cyclic acene (y0 = y1 = 0.320) is 4.89 × 103 a.u. which is about 6 times larger than those of 0.80 × 103 a.u. for closed‐shell [5]cyclophenylene. Similarly, γzzzz value of [5]linear acene is also about 9 times larger than its closed‐shell [5]linear phenylene counterpart. Our results show interesting insights into the relationship among the architectures, diradical characters and γzzzz values of different acenes and phenylenes. © 2012 Wiley Periodicals, Inc.

Application of Multifunctional X-Doped Sumanene (X= Si, Ge, O, S and Se) for Concave–Convex Supramolecular Assembly with C60 and Their Nonlinear Optical Properties

“…In the present study, we design and investigate the concave–convex complexes 1 ⊃ C 60 , 2 ⊃ C 60 , 3 ⊃ C 60 , 4 ⊃ C 60 , and 6 ⊃ C 60 formed between the heteroatom-doped buckybowls and fullerene spheres on the basis of the synthesized crystalline structure of 5 ⊃ C 60 . Continuing previous studies on the structures and properties of D–A systems, organic classes, − and fullerenes, − we investigate the structures, binding interactions, and electronic absorption spectra of the complexes formed by X-doped sumanene (X = Si, Ge, O, S, and Se) and C 60 , with the aim to investigate the influence of the bowl depth of the buckybowl on binding interactions and transition energies of complexes. Significantly, the donor–acceptor charge transfer between buckybowls and fullerene aroused our interests to investigate their first hyperpolarizabilities and reveal the relationship between intermolecular interaction and nonlinear optical (NLO) property.…”

Multilithiation Effect on the First Hyperpolarizability of Carbon–Boron–Nitride Heteronanotubes: Activating Segment versus Connecting Pattern

“…Up to now, great efforts have been devoted to design and synthesize high-performance NLO molecules due to their potential applications in laser devices. − It is worthy of note that the static first hyperpolarizability (β 0 ) is the microscopic parameter of the macroscopic second NLO response of materials, which could be effectively adjusted by many strategies. , For example, the reported strategies to enhance β 0 include the use of molecules with abundant π-electrons, − the introduction of donor/acceptor groups, − and incorporation of a transition metal atom with organic compounds, ,, etc. Recently, the lithiation effect on the β 0 of the acene system and supershort single-walled carbon nanotubes has been investigated by our group.…”

Cycloparaphenylenes and related nanohoops

“…On the same day, Nakano and co-workers published a computational study contrasting CPPs with linear oligophenylenes, as well as cyclic and linear acenes. 52 They employed long-range corrected spin-unrestricted density functional theory (LC-UDFT) to investigate the diradical character of the species under study, finding that CPPs and linear oligophenylenes have closed shell configurations, whereas both linear and cyclic acenes have singlet diradical character. The group also calculated the various third-order non-linear optical polarisabilities.…”