Details

Autor(en) / Beteiligte

• Minamida, Yuka
• Kishi, Ryohei
• Fukuda, Kotaro
• Matsui, Hiroshi
• Takamuku, Shota
• Yamane, Masaki
• Tonami, Takayoshi
• Nakano, Masayoshi

Titel

Tunability of Open‐Shell Character, Charge Asymmetry, and Third‐Order Nonlinear Optical Properties of Covalently Linked (Hetero)Phenalenyl Dimers

Ist Teil von

• Chemistry : a European journal, 2018-02, Vol.24 (8), p.1913-1921

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2018

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Tunability of the open‐shell character, charge asymmetry, and third‐order nonlinear optical (NLO) properties of covalently linked (hetero)phenalenyl dimers are investigated by using the density functional theory method. By changing the molecular species X and substitution position (i, j) for the linker part, a variety of intermonomer distances R and relative alignments between the phenalenyl dimers can be realized from the geometry optimizations, resulting in a wide‐range tuning of diradical character y and charge asymmetry. It is found that the static second hyperpolarizabilities along the stacking direction, γyyyy, are one‐order enhanced for phenalenyl dimer systems exhibiting intermediate y, a feature that is in good agreement with the “y–γ correlation”. By replacing the central carbon atoms of the phenalenyl rings with a boron or a nitrogen, we have also designed covalently linked heterophenalenyl dimers. The introduction of such a charge asymmetry to the open‐shell systems, which leads to closed‐shell ionic ground states, is found to further enhance the γyyyy values of the systems having longer intermonomer distance R with intermediate ionic character, that is, charge asymmetry. The present results demonstrate a promising potential of covalently linked NLO dimers with intermediate open‐shell/ionic characters as a new building block of highly efficient NLO systems. Tuning nonlinear optical dimers: Open‐shell characters, charge asymmetry, and third‐order nonlinear optical properties of covalently linked (hetero)phenalenyl dimers are investigated by density functional calculations. By changing the linker species, the diradical/ionic characters can be finely tuned to achieve significantly enhanced second hyperpolarizability (see scheme).