3 years ago

Femto-to nanosecond photodynamics of Nile Red in metal-ion exchanged faujasites

Femto-to nanosecond photodynamics of Nile Red in metal-ion exchanged faujasites
We report on the photodynamics of Nile Red (NR) interacting with faujasite (NaY)-type zeolites having different Na/Al ratios and charge balancing metals (Li+, Mg2+, and Cs+) in dichloromethane (DCM) suspensions. The encapsulation of NR in these materials leads to the formation of different populations, reflected in H- and J-aggregates, monomers, and surface adsorbed species. Due to the interaction of the dye with both the Brønsted and Lewis sites of the zeolite, a bathochromic shift is observed in the steady-state diffuse transmittance and emission spectra. The relative contribution of each population is affected by the Na/Al ratio and the nature of the doping metal ion. These findings are further explored by femto-to nanosecond time-resolved emission experiments, where a multi-exponential behaviour is observed for the excited samples. The fluorescence lifetimes range from ∼100 ps to ∼2 ns. They are assigned to the emission from H- and J-aggregates and monomers. At low Na/Al ratios, we observed an increase in the fluorescence time constants which is explained in terms of H-bonds formation between NR and the zeolite framework, while the change in the emission lifetimes for the metal ion exchanged zeolites is due to the variation of the properties (size and polarization ability) of the exchanged cation. An ultrafast formation (∼200 fs) of a charge-separated state (CS) followed by a vibrational cooling (∼1–2 ps) are observed in the fluorescence up-conversion transients. These results indicate a strong interaction between NR and the studied zeolites and may help for the design of metal ion sensors and for a better understanding of nanocatalysis.

Publisher URL: www.sciencedirect.com/science

DOI: S1387181117305474

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.