Diradicalology in third‐order nonlinear optical systems: Second hyperpolarizabilities of acetylene‐linked phenalenyl‐based superpolyenes. Issue 4 (23rd February 2012)

• Record Type: Journal Article
• Authors: Nakano, Masayoshi; Kishi, Ryohei; Fukui, Hitoshi; Minami, Takuya; Yoneda, Kyohei; Minamide, Shu; Inoue, Yudai; Yamada, Taishi; Ito, Soichi; Muhammad, Shabbir; Shigeta, Yasuteru; Kubo, Takashi; Champagne, Benoît; Nakai, Hiromi; Yoshizawa, Kazunari; Ando, Koji; Nakajima, Takahito; Brändas, Erkki J.
• Is Part Of: International journal of quantum chemistry. Volume 113:Issue 4(2013:Feb. 15)
• Page Start: 585
• Page End: 591
• Publication Date: 2012-02-23
• Subjects: Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.24035
• Languages: English
• ISSNs: 0020-7608

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>From the viewpoint of "diradical character, " referred to as "diradicalology, " we investigate the second hyperpolarizability γ—the molecular third‐order nonlinear optical (NLO) property—of one‐dimensional supermolecular systems composed of acetylene‐linked phenalenyl/pyrene rings using long‐range corrected spin‐unrestricted density functional theory. It turns out that the pyrene‐based superpolyenes (Py‐<italic>n</italic>) behave like closed‐shell systems, whereas phenalenyl‐based superpolyenes (Ph1‐<italic>n</italic> and Ph2‐<italic>n</italic>) have different diradical characters depending on the linked form, that is, Ph1‐<italic>n</italic> and Ph2‐<italic>n</italic> have intermediate and pure diradical characters, respectively. In comparison with Py‐<italic>n</italic> and Ph2‐<italic>n</italic>, the longitudinal γ of Ph1‐<italic>n</italic> is significantly larger, and it displays larger enhancement as a function of system size. Substitutions to the terminal rings by donor (NH<sub>2</sub>) and acceptor (NO<sub>2</sub>) groups further enhance γ in Ph1‐<italic>n</italic>, more than in Ph2‐<italic>n</italic> and Py‐<italic>n</italic>. These results are in agreement with the structure–property relationships derived for open‐shell NLO systems with symmetric and asymmetric charge distributions (Nakano et al., <italic>J. Chem. Phys</italic>. 2010, <italic>133</italic>, 154302). © 2012 Wiley Periodicals, Inc.</p> </abstract>