π-Stacked supramolecular contact ion pairs prohibit quenching and provide control of symmetry in fluorescent dyes
- 1Nano-Science Center & Department of Chemistry, University of Copenhagen Universitetsparken 5 Copenhagen 2100 Denmark
- 2Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington 47405 Indiana USA
Abstract
Cationic chromophores like cyanines and xantheniums are prevalent fluorescent dyes used for imaging and as probes. In non-polar environments, however, electrostatic interactions drive formation of ion pairs with the accompanying anions that may assemble further into aggregates of ion-pairs, strongly affecting and deteriorating photophysical properties. Here, we investigate contact ion pairs and higher order aggregates of cationic fluorophores by leveraging a symmetry-sensitive amino-triangulenium dye (ATOTA+) and its combination with anion-binding macrocycle cyanostar (CS). Absorption, fluorescence, and NMR titrations in non-polar solvents show that cyanostar binds the dye's counter ions (X−) in a stable 2 : 1 sandwich-like anion complex (CS2X−) that prohibits dye aggregation. Fluorescence anisotropy and energy transfer measurements show that ATOTA+ and the CS2X− anion complex form well-defined and tightly π-stacked contact ion pairs resulting in highly increased fluorescence quantum yield and lifetime. These effects are found to be general. Addition of cyanostar to six cationic dyes (rhodamine, cyanine, oxazine, triangulenium and styryl type chromophores) in benzene solutions and polystyrene thin films improves photophysical properties assigned to the supramolecular contact ion-pairs formed between dyes and the cyanostar–anion complex.
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BibTeX
@article{kacenauskaite2026πstacked,
title = {{π-Stacked supramolecular contact ion pairs prohibit quenching and provide control of symmetry in fluorescent dyes}},
author = {Laura Kacenauskaite and Andrew H. Olsson and Tumpa Sadhukhan and Krishnan Raghavachari and Amar H. Flood and Bo W. Laursen},
journal = {Chemical Science},
year = {2026},
month = sep,
doi = {10.1039/d6sc04162k},
url = {https://doi.org/10.1039/d6sc04162k},
note = {CC BY-NC 3.0},
}
RIS
TY - JOUR
TI - π-Stacked supramolecular contact ion pairs prohibit quenching and provide control of symmetry in fluorescent dyes
AU - Laura Kacenauskaite
AU - Andrew H. Olsson
AU - Tumpa Sadhukhan
AU - Krishnan Raghavachari
AU - Amar H. Flood
AU - Bo W. Laursen
PY - 2026
DA - 2026/09/08
JO - Chemical Science
DO - 10.1039/d6sc04162k
UR - https://doi.org/10.1039/d6sc04162k
AB - Cationic chromophores like cyanines and xantheniums are prevalent fluorescent dyes used for imaging and as probes. In non-polar environments, however, electrostatic interactions drive formation of ion pairs with the accompanying anions that may assemble further into aggregates of ion-pairs, strongly affecting and deteriorating photophysical properties. Here, we investigate contact ion pairs and higher order aggregates of cationic fluorophores by leveraging a symmetry-sensitive amino-triangulenium dye (ATOTA+) and its combination with anion-binding macrocycle cyanostar (CS). Absorption, fluorescence, and NMR titrations in non-polar solvents show that cyanostar binds the dye's counter ions (X−) in a stable 2 : 1 sandwich-like anion complex (CS2X−) that prohibits dye aggregation. Fluorescence anisotropy and energy transfer measurements show that ATOTA+ and the CS2X− anion complex form well-defined and tightly π-stacked contact ion pairs resulting in highly increased fluorescence quantum yield and lifetime. These effects are found to be general. Addition of cyanostar to six cationic dyes (rhodamine, cyanine, oxazine, triangulenium and styryl type chromophores) in benzene solutions and polystyrene thin films improves photophysical properties assigned to the supramolecular contact ion-pairs formed between dyes and the cyanostar–anion complex.
SN - 2041-6520
SN - 2041-6539
ER -