Dye-Loaded Zeolite L Sandwiches as Artificial Antenna Systems for Light Transport

Abstract

The synthesis and characterization of dye loaded zeolite L sandwiches acting as artificial antenna systems for light harvesting and transport is reported. A set of experimental tools for the preparation of neutral dye-zeolite L materials ranging from low to maximum packing densities has been developed. The role of co-adsorbed water and the distribution of molecules between the inner and the outer surface were found to be the determining parameters. p-Terphenyl (pTP) turned out to be very suitable for studying these and other relevant parameters of neutral dye-zeolite L materials. We observed that pTP located in the channels of zeolite L can reversibly be displaced by water. This can be used when synthesizing such materials. We also observed that all-trans-1,6-diphenyl-1,3,5-hexatriene (DPH) which is very photolabile in solution is stable after insertion into zeolite L. By combining our extensive knowledge of these systems with ion-exchange procedures developed in an earlier study, we have realized the first bi-directional three-dye antenna. In this material the near UV absorbing compounds DPH or 1,2-bis-(5-methyl-benzoxazol-2-yl)-ethene (MBOXE) are located in the middle part of zeolite L nanocrystals followed on both sides by pyronine (Py) and then by oxonine (Ox) as acceptors. Fluorescence of the oxonine located at both ends of the cylindrical zeolite L crystals was observed upon excitation of the near UV absorber in the middle section at 353 nm, where neither oxonine nor pyronine absorb a significant amount of the excitation light.

The high thermal stability of the synthetic zeolite K–L: Dehydration mechanism by in situ SR-XRPD experiments

“…In view of the well-known affinity of zeolites for water, stability of the hybrid materials upon hydration is particularly critical. In fact, in many dye-zeolite composites exposed to air at room temperature (RT), as a consequence of the entrance of water molecules, a displacement of the organic dye from the channels is observed [11]. Upon heating, and hence drying, the guest molecules can be re-inserted.…”

Fluorescent nanopigments: Quantitative assessment of their quantum yield

“…1͑a͔͒. 22,62,63 Note that, in order to perform DR measurements, the ZL-P nanoparticles are adsorbed into microcrystalline cellulose substrates using a solvent evaporation method under heating and reduced pressure ͑see below͒. Therefore, in order to guarantee the nanopigment stability ͑i.e., to prevent the leakage of the neutral dye molecules͒, a well-known plugging method was adopted.…”

“…In particular, both organic-inorganic [14][15][16] and organic-organic [17][18][19] host-guest nanosystems have been extensively developed for the chemical, photochemical or thermal stabilization and the supramolecular organization of organic fluorescent dye molecules, complexes, and clusters. [19][20][21][22][23][24][25] The most common examples of such systems are ͑i͒ nanoporous zeolites: besides their widespread commercial use as catalysts and ion-exchangers, 26 due to their nanoporous framework consisting of nanochannels with a minimal diameter of several angstrom, they have been used as inorganic hosts for the encapsulation of different organic molecules, 2,20-22,27-31 ͑ii͒ mesoporous silica particles: because of their uniform porosity, they have been recently proposed as promising inorganic hosts with an adjustable pore size in the range of 1-10 nm, 32-35 ͑iii͒ silica nanoparticles: once loaded with fluorescent organic dyes, these inorganic nanohosts have been shown to possess interesting physical-chemical and photochemical properties, [36][37][38][39][40] ͑iv͒ fluorescent polymer nanoparticles: as stable organic hosts, they have attracted both research 6,8,[17][18][19]23,25,41 and commercial 42 interest for the development and the fabrication of novel functional materials; ͑v͒ organic-organic supramolecular complexes: they have been developed using organic macromolecules as hosts that can encapsulate small organic molecules or ions. 43,44 Due to their high versatility, these host-guest systems offer a wide range of possibilities for preparing nanopigments with tailored chemical and physical properties.…”

“…In this article, we present an optical technique that allows the direct measurement of the absolute quantum yield of fluorescent nanoparticles such as zeolite L ͑ZL͒ nanocrystals 2,[20][21][22][28][29][30][31] and poly͑methyl methacrylate͒ ͑PMMA͒ nanospheres 5,17,19,[23][24][25]53,54 both loaded with fluorescent perylene molecules, which are well known for their chemical and photochemical stabilities as well as for their high quantum yield. 5,55 Our experimental method is based on the measurement of the diffuse reflectance ͑DR͒ spectra of fluorescent nanopigments adsorbed on microcrystalline cellulose substrates.…”

Quantum Yield Measurement of Fluorescent Zeolite Nanopigments

“…[2] Synthesis procedures have been established to embed different organic molecules into zeolite L and to study several photochemical and photochromic processes. [3,4] In particular, the geometrical constraints of the host framework lead to the supramolecular organization of the guest molecules into the channels. [5] For instance, including fluorescent dyes into zeolite L has enabled the fabrication of new fluorescent pigments.…”