What question did this study set out to answer?

The research examines how molecular charge density affects the self-assembly kinetics of porphyrin derivatives into J-aggregates.

May 14, 2026

Tuning Hofmeister ion sensitivity in porphyrin J-aggregation through molecular charge density

Puntos clave

The research examines how molecular charge density affects the self-assembly kinetics of porphyrin derivatives into J-aggregates.
Investigated three sulfonato-phenylporphyrins: TPPS4, TPPS3, and [Formula: see text]-TPPS2.
Used UV/Vis spectroscopy to track changes in aggregation over time, noting specific wavelength shifts.
Analyzed kinetic parameters according to Pasternack’s model and correlated with Hofmeister series behavior.
TPPS4 and [Formula: see text]-TPPS2 aggregation rates followed the Hofmeister series, showing superlative correlation with anionic structure-making abilities.
[Formula: see text]-TPPS2 exhibited aggregation kinetics an order of magnitude faster than TPPS4.
TPPS3 displayed deviations from expected Hofmeister behavior, highlighting its unique morphology with smaller critical nucleus sizes.

Resumen

This study investigates the self-assembly kinetics of three structurally related sulfonato-phenylporphyrins, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPSFormula: see text, 5,10,15-tris (4-sulfonatophenyl)-20-phenyl-porphyrin (TPPSFormula: see text and 5,15-bis(4-sulfonatophenyl)-10,20-phenyl-porphyrin (Formula: see text-TPPSFormula: see text into supramolecular J-aggregates in acidic aqueous solutions, using a series of inorganic acids. The aggregation process, followed by UV/Vis spectroscopy, monitoring the characteristic B-band disappearance (434 nm) and the sharp, red-shifted J-band appearance (490 nm), exhibits typical sigmoidal, autocatalytic kinetic profiles. Kinetic parameters derived from Pasternack’s model reveal that TPPS 4 and t-TPPS 2 aggregation rates adhere to the Hofmeister series for anions (SOFormula: see text ClFormula: see text BrFormula: see text NOFormula: see text ClOFormula: see text, correlating linearly with the anions’ structure-making/breaking abilities. Notably, Formula: see text-TPPS 2 kinetics are an order of magnitude faster than TPPS 4 . In contrast, TPPS 3 exhibits deviations from Hofmeister behavior together with smaller critical nucleus sizes, likely reflecting its distinct nano-ribbon morphology compared with the nano-tubes/stacked platelets structures formed by the other porphyrins. This work highlights how subtle molecular changes and the ionic environment tune macroscopic material properties via non-covalent interactions.

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