Premium
Triangular Rhodamine Triads and Their Intrinsic Photophysics Revealed from Gas‐Phase Ion Fluorescence Experiments
Author(s) -
Zhao Ying,
Sørensen Emma Rostal,
Lindkvist Thomas Toft,
Kjær Christina,
Brøndsted Nielsen Mogens,
Chen Li,
Brøndsted Nielsen Steen
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202101322
Subject(s) - chemistry , excited state , polarizability , photochemistry , chromophore , dipole , ion , rhodamine , fluorescence anisotropy , fluorescence , emission spectrum , electric field , molecular physics , spectral line , atomic physics , molecule , optics , physics , organic chemistry , astronomy , quantum mechanics
When ionic dyes are close together, the internal Coulomb interaction may affect their photophysics and the energy‐transfer efficiency. To explore this, we have prepared triangular architectures of three rhodamines connected to a central triethynylbenzene unit (1,3,5‐tris(buta‐1,3‐diyn‐1‐yl)benzene) based on acetylenic coupling reactions and measured fluorescence spectra of the isolated, triply charged ions in vacuo. We find from comparisons with previously reported monomer and dimer spectra that while polarization of the π‐system causes redshifted emission, the separation between the rhodamines is too large for a Stark shift. This picture is supported by electrostatic calculations on model systems composed of three linear and polarizable ionic dyes in D 3h configuration: The electric field that each dye experiences from the other two is too small to induce a dipole moment, both in the ground and the excited state. In the case of heterotrimers that contain either two rhodamine 575 (R575) and one R640 or one R575 and two R640, emission is almost purely from R640 although the polarization of the π‐system expectedly diminishes the dipole‐dipole interaction.