Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite L

Abstract

Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host-guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 micros) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 micros). A model of the host-guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations.

Designing Dye–Nanochannel Antenna Hybrid Materials for Light Harvesting, Transport and Trapping

“…We know for example, that esters often tend to hydrolyze in the usually acidic environment. [62,80] The behavior of fluorenone inside of ZL has been studied in detail experimentally [81] and by means of advanced quantum chemical calculations. [79] Easy substitution by water, which is a common phenomenon for nonpolar, neutral dyes like biphenyl, terphenyl, anthracene, and many others, [69] is not observed for fluorenone and for furo[3,4-c]furanone.…”

First-principles simulation of the absorption bands of fluorenone in zeolite L

“…2 shows the absorption spectra of fluorenone measured in cyclohexane and in hydrated zeolite L as reported originally in ref. 33. Due to the small values of the molecular extinction coefficient at long wavelengths, the intensities are shown on the logarithmic scale in all the figures subsequently discussed in this work.…”

Close-Packed Dye Molecules in Zeolite Channels Self-Assemble into Supramolecular Nanoladders

“…17,18,19,20,21 This is a key requirement for the fabrication of increasingly sophisticated optical devices which might open novel pathways in areas such as solar energy harvesting, information processing and nanodiagnostics. 22,23,24 Zeolite L (ZL) is a very appealing host matrix for the realization of one dimensional photoactive domains. Due to the narrow openings (free diameter 7.8 Å) and maximum diameter (~12 Å) of its channels, sufficiently bulky dye molecules are constrained to align to the channel axis and are prevented from passing each other.…”

“…36,37 All of these studies were performed by modeling a low dye loading in order to mimic the dye concentrations generally adopted in actual dye-ZL composites, which are normally below 0.5 molecules per unit cell. 23 The structure, properties and behavior of highly packed dye-ZL materials, 4 i.e., characterized by a high degree of dye loading, have never been explored to date, neither by experiment, nor by modeling. A deep understanding of this regime might provide novel ideas and alternative routes for advances in the fabrication of ZL-based devices, and this work represents the first contribution toward this goal.…”