J-aggregation in indolenine dyes drives fluorescent crystals with large Stokes shifts and two-photon excited emission
Journal article, 2026
Organic fluorescent solids are highly demanded for applications such as sensing and bioimaging, yet most of these systems require co-crystallization with additional components to avoid aggregation-caused quenching. Here, the intermolecular assembly and resulting photophysical properties of a series of indolenine-based dyes are described. These dipolar donor-π-acceptor (D-π-A) structures are composed to favor head-to-tail interactions, rendering most of them with an exceptional ability for J -aggregate formation. Due to their tailored molecular architecture, J -aggregation features pair with unusually large Stokes shifts in both concentrated solutions and solid state (up to 3,272 cm−1 in aggregates and 6,135 cm−1 in solid state), enabling two-photon excited fluorescence (2PEF). Unlike most 2PEF-active condensed organic systems, these dyes spontaneously form single-component fluorescent crystals upon solvent evaporation, i.e., without requiring co-crystallization with additional components. The resulting crystals exhibit a pronounced and fully reversible vapochromic response, readily allowing the development of simple and robust sensing devices.
J-aggregation
solid-state fluorescence
two-photon absorption
sensors
non-linear optics
Author
Carlos Benitez Martin
University of Gothenburg
University of Malaga
Instituto de Investigación Biomédica de Málaga (IBIMA)
Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry
Yolanda Vida
University of Malaga
Instituto de Investigación Biomédica de Málaga (IBIMA)
Enrique R. Losilla
University of Malaga
Aurelio Cabeza
University of Malaga
Francisco Najera
University of Malaga
Instituto de Investigación Biomédica de Málaga (IBIMA)
E. Perez-Inestrosa
Instituto de Investigación Biomédica de Málaga (IBIMA)
University of Malaga
Cell Reports Physical Science
26663864 (eISSN)
Vol. 7 9 103509Subject Categories (SSIF 2025)
Condensed Matter Physics
Organic Chemistry
Physical Chemistry
DOI
10.1016/j.xcrp.2026.103509