We report the preparation and investigation of hierarchically organized host-guest structures, presenting successive ordering from the molecular up to macroscopic scale, thus supporting the relationship between the molecular arrangements and the macroscopic properties. Size, shape and surface composition of the host which is zeolite L play a decisive role. Its base and coat have distinctively different chemical properties. The guests, organic dye molecules or complexes, are well oriented inside the channels and can be organized into distinctive patterns. Zeolite L crystals containing oriented fluorophores in their parallel nanochannels possess remarkable fluorescent properties and they can be arranged in nearly any desired manner by means of self-organization methods. This makes them ideal host-guest structures for the exploitation of energy transfer and energy funneling processes. Size, shape and surface composition of the objects but also the properties of the surface on which they should be organized play a decisive role. We present a simple model of an artificial antenna based on supramolecular organization of dyes in nanochannels of the host, and we explain why zeolite L can be considered as an ideal host for this purpose. The preparation of different dye-zeolite L materials is described, and Förster energy transfer experiments carried out with them. Further, increasing supramolecular organization is discussed: the first unidirectional antenna system on a macroscopic level, organization of crystals and communication of the crystals interior with the environment. Additionally, we explain spectroscopy on monolayers of dye-zeolite L micro-crystals. The materials are shown to be new building blocks for optical, electro-optical and sensing devices.
Host-guest materials containing strongly fluorescent donor and acceptor molecules have been prepared. Finetuning of the donor to acceptor distance in this material allows beautiful visible and quantitative observation of electronic excitation energy transfer phenomena. Oxonine and pyronine have been used as guest molecules and zeolite L as host. The dyes have been inserted by ion exchange. Stationary state and time-resolved experiments have been carried out with zeolite crystals of 300 and 700 nm size in the dye concentration range of 10 -4 mol/L up to 0.042 mol/L. The fluorescence decay of the donor and the pumping of the acceptor via energy transfer, which can be well observed, became faster with increasing loading. The behavior of the system follows requirements expected for Förster energy transfer material.
Interdisciplinarity is as trendy as it is difficult to define. Instead of trying to capture a multidimensional object with a single indicator, we propose six indicators, combining three different operationalizations of a discipline, two levels (article or laboratory) of integration of these disciplines and two measures of interdisciplinary diversity. This leads to a more meaningful characterization of the interdisciplinarity of laboratories' publication practices. Thanks to a statistical analysis of these indicators on 600 CNRS laboratories, we suggest that, besides an average value of interdisciplinarity, different laboratories can be mainly distinguished by the ''distance'' between the disciplines in which they publish and by the scale at which interdisciplinary integration is achieved (article or laboratory).
The supramolecular organisation of molecules, complexes or clusters is a fruitful concept for the design of systems exhibiting specific macroscopic properties. The encapsulation of guest species into the pores or channels of host materials presents a challenging approach to the preparation of novel chemical and optical materials. Zeolite L has been shown to be an ideal host for the supramolecular organisation of organic dyes. A new hierarchy of structural ordering can be achieved by either arranging the zeolite L crystals into densely packed, oriented monolayers or by interfacing them to the environment via molecules bound to the edges of the crystals. These concepts are reviewed here, as well as some potential applications.
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