Structure and Host-Guest Interactions of Perylene-Bisimide Dyes in Zeolite L Nanochannels.

Confinement-driven self-assembly of dyes in nanomatrices is an effective route for the production of hybrid supramolecular structures of high technological relevance, among which the archetypal zeolite L-based systems are exploited in Forster Resonance Energy Transfer (FRET)-sensitized solar cells, luminescent solar concentrators, color-changing media, but also sensing in analytical chemistry, biology, and diagnostics. Despite this progress in applications, the organization of confined chromophores in zeolite L materials remains elusive. Herein, by integrating experiments with different time scale and radiation source (IR, XRPD, Total Scattering) with first-principles DFT modeling, we attained a microscopically detailed picture of a technologically important hybrid composite of Zeolite L with a perylene-diimide (also known as perylene-bisimide) dye at both hydrated and anhydrous conditions. The asymmetric positioning of the dye in the zeolite channel is determined by two factors: shape-volume constraints, and relative strength of competitive interactions among confined species. Our multi-technique experimental-theoretical approach thoroughly described the supramolecular chemistry of this hybrid material, identifiying possible strategies to further enhance FRET efficiency and improve functionality. This work deepens the understanding of host-guest interactions in dye-Zeolite L composites, a key requirement to master the finely-tuned mechanisms governing supramolecular organization in confined nanospaces.