title: Circularly Polarized Luminescence of Chiral Pt(pppb)Cl (pppbH=1-pyridyl-3-(4,5-pinenopyridyl)benzene) Aggregate in the Excited State.
abstract: We prepared enantiomers of chiral Pt(II) complexes, Pt(pppb)Cl and Pt(pppb)CN (pppbH=1-pyridyl-3-(4,5-pinenopyridyl)benzene), and measured their CPL (circularly polarized luminescence) spectra for excimer and trimer emission. The contribution of the pinene moiety to CPL was considerably low for the π-π* emission of the monomer but large for MMLCT (metal-metal-to-ligand charge-transfer) of the excimer and trimer which had a helical structure induced in a face-to-face stacking fashion. The trimer CPL for (+)-Pt(pppb)Cl was larger in intensity than that of excimer CPL; on the other hand, that for (+)-Pt(pppb)CN was opposite in sign compared with that of excimer CPL. We conclude that differences in the excited-state structure of the aggregate between Pt(pppb)Cl and Pt(pppb)CN account for the variation in the CPL spectra. By the aid of TD-DFT calculations it was predicted that the dihedral angle θ(Cl-Pt-Pt-Cl) was 50-60° or 110-140° for Pt(pppb)Cl aggregates and 160° for Pt(pppb)CN aggregates.
authors.affiliation: Department of Materials System Science, Graduate School of Nanobiosystem Sciences, Yokohama City University, 22-2 Seto, Yokohama, 236-0027, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Materials System Science, Graduate School of Nanobiosystem Sciences, Yokohama City University, 22-2 Seto, Yokohama, 236-0027, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Sato
authors.affiliation: Department of Materials System Science, Graduate School of Nanobiosystem Sciences, Yokohama City University, 22-2 Seto, Yokohama, 236-0027, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ichida
authors.affiliation: Sumitomo Chemical Co. Ltd., 6 Kitahara, Tsukuba, Ibaraki, 300-3294, Japan.
authors.forename: Taichi
authors.initials: T
authors.lastname: Abe
authors.affiliation: Department of Materials and Life Science, Seikei University, Kichijoji-kitamachi, Musashino, Tokyo, 180-8633, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Tsubomura
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-3-1 Tsushimanaka, Okayama, 700-8530, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Materials System Science, Graduate School of Nanobiosystem Sciences, Yokohama City University, 22-2 Seto, Yokohama, 236-0027, Japan. shino@yokohama-cu.ac.jp.
authors.forename: Kazuteru
authors.initials: K
authors.lastname: Shinozaki
mesh_terms: D049449:Luminescence; D008958:Models, Molecular; D015394:Molecular Structure; D017671:Platinum Compounds / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D017671:Platinum Compounds
keywords: circularly polarized luminescence; excimer; excited-state structure; metal-metal interaction; platinum complex