TY - JOUR
T1 - Circularly Polarized Luminescence of Chiral Pt(pppb)Cl (pppbH=1-pyridyl-3-(4,5-pinenopyridyl)benzene) Aggregate in the Excited State
AU - Tanaka, Saori
AU - Sato, Kyohei
AU - Ichida, Kyoko
AU - Abe, Taichi
AU - Tsubomura, Taro
AU - Suzuki, Takayoshi
AU - Shinozaki, Kazuteru
N1 - Funding Information:
This work was supported by JSPS KAKENHI Grant No. 122455008882.
Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2016/1/20
Y1 - 2016/1/20
N2 - We prepared enantiomers of chiral PtII 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.
AB - We prepared enantiomers of chiral PtII 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.
KW - circularly polarized luminescence
KW - excimer
KW - excited-state structure
KW - metal-metal interaction
KW - platinum complex
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U2 - 10.1002/asia.201500985
DO - 10.1002/asia.201500985
M3 - Article
C2 - 26450766
AN - SCOPUS:84958831935
SN - 1861-4728
VL - 11
SP - 265
EP - 273
JO - Chemistry - An Asian Journal
JF - Chemistry - An Asian Journal
IS - 2
ER -