No abstract

A series of π conjugated naphthalimide derivatives having an imide group as an acceptor conjugated with a methoxy arylethynyl or a methoxyphenyl triazole as a donor were prepared by Sonogashira coupling or "click" chemistry. Their photophysical properties were investigated by steady state and time resolved fluorescence spectroscopy and modelled by TD-DFT calculations. Compound Naphth-AlkyneOMe has a high fluorescence quantum yield and displays efficient photoinduced charge transfer in solution as well as in the powder state. Compound Naphth-TriazoleOMe exhibits a very high Stokes shift and its fluorescence quantum yield is low, which can be rationalized by theoretical calculations.

The association of host-guest and coordination chemistry was used to develop a fluorescent molecular sensor. A calix[6]arene bearing three imidazole arms at the small rim and three quinoline fluorophores at the large rim was synthesized and characterized. A two-step coordination sequence was observed upon addition of Zn . The first Zn center binds the tris-imidazole small rim site, leading only to a small perturbation of the fluorescence. In contrast, a large bathochromic shift is observed upon binding of the second Zn center at the large rim as a result of the direct interaction of Zn with the quinoline fluorophores. The system acts as a selective receptor for primary amines. Host-guest adduct formation could be identified by a shift and enhancement of the fluorescence emission that is dependent on the length and shape of the primary amine. This system constitutes a fluorescent reporter with a selective response among primary amines.

A fluorimetric reporting of neutral guest‐hosting allows for the first achievement in the chemistry of the calix[6]arene‐based funnel complex family. An induced‐fit process accompanying guest‐hosting modulates the relative arrangement and the mobility of three quinoline moieties at the large rim, as well as their fluorescence response. The system is remarkable because it selectively recognizes and reports primary amines with a backbone fitting the cavity, and it is also specific, with the nature and magnitude of the response reflecting the nature of this backbone (amine chain length in particular). More information can be found in the Full Paper by I. Leray, O. Reinaud et al. on page 8669.