Excited-State Symmetry Breaking in an Aza-Nanographene Dye

被引：15

作者：

Bardi, Brunella ^{[1
]}

Krzeszewski, Maciej ^{[2
]}

Gryko, Daniel T. ^{[2
]}

Painelli, Anna ^{[1
]}

Terenziani, Francesca ^{[1
]}

机构：

[1] Univ Parma, Dept Chem Life Sci & Environm Sustainabil, Parco Area Sci 17-A, I-43124 Parma, Italy

[2] Polish Acad Sci, Inst Organ Chem, Kasprzaka 44-52, PL-01224 Warsaw, Poland

来源：

CHEMISTRY-A EUROPEAN JOURNAL | 2019年 / 25卷 / 61期

基金：

欧盟地平线“2020”;

关键词：

charge transfer; computational chemistry; fused-ring systems; polarized spectroscopy; solvatochromism; DENSITY-FUNCTIONAL THEORY; NONLINEAR-OPTICAL PROPERTIES; CHARGE-TRANSFER; 2-PHOTON ABSORPTION; QUADRUPOLAR CHROMOPHORES; PUSH-PULL; EXCITATION-ENERGIES; MOLECULES; SOLVATOFLUOROCHROMISM; SOLVATOCHROMISM;

D O I：

10.1002/chem.201902554

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

The photophysics of a structurally unique aza-analogue of polycyclic aromatic hydrocarbons characterized by 12 conjugated rings and a curved architecture was studied in detail. The combined experimental and computational investigation reveals that the lowest excited state has charge-transfer character, in spite of the absence of any peripheral electron-withdrawing groups. The exceptionally electron-rich core comprised of two fused pyrrole rings is responsible for it. The observed strong solvatofluorochromism is related to symmetry breaking occurring in the emitting excited state, leading to a significant dipole moment (13.5 D) in the relaxed excited state. The anomalously small fluorescence anisotropy of this molecule, which is qualitatively different from what is observed in standard quadrupolar dyes, is explained as due to the presence of excited states that are close in energy but have different polarization directions.

引用

页码：13930 / 13938

页数：9