Chemosensors detect a single target molecule from among several molecules, but cannot differentiate targets from one another. In this study, we report a molecular decoding strategy in which a single host domain accommodates a class of molecules and distinguishes between them with a corresponding readout. We synthesized the decoding host by embedding naphthalenediimide into the scaffold of an entangled porous framework that exhibited structural dynamics due to the dislocation of two chemically non-interconnected frameworks. An intense turn-on emission was observed on incorporation of a class of aromatic compounds, and the resulting luminescent colour was dependent on the chemical substituent of the aromatic guest. This unprecedented chemoresponsive, multicolour luminescence originates from an enhanced naphthalenediimide–aromatic guest interaction because of the induced-fit structural transformation of the entangled framework. We demonstrate that the cooperative structural transition in mesoscopic crystal domains results in a nonlinear sensor response to the guest concentration.

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We report the photophysical properties of new BODIPY derivatives monosubstituted at the central position. The presence of different functional groups induced the appearance of new photophysical processes in BODIPY dyes, such as intramolecular charge or energy transfer. These phenomena are sensitive to solvent properties (mainly the polarity) and have a potential use as fluorescent probes. Adequate modifications in their molecular structure or in the environment polarity can modulate the emission region of these fluorophores in the visible spectral region. Specifically, different processes and photophysical behaviors can be achieved depending on the excited chromophore and/or the solvent characteristics in a bichromophoric pyrene-BODIPY system.

A new fluorescence polarization method is applied to evaluate the preferential orientation of rhodamine 6G (R6G) adsorbed into laponite (Lap) clay mineral in supported films. For this purpose, the fluorescence spectra for the horizontal and vertical directions of the emission polarizer were recorded for a common horizontally polarized excitation light as a function of the twist angle δ of the film with respect to the excitation (and emission) beam. The orientation of the fluorescent species adsorbed in the clay films can be evaluated from the linear relationship between the fluorescence dichroic ratio and the twist angle δ recently established. , For low dye-loading R6G, molecules are adsorbed into the Lap surface as monomeric units with a tilt ψ angle of 28° with respect to the clay layer, in agreement with results obtained by visible absorption with polarized light. Fluorescent coplanar J type dimers of R6G are also observed in Lap films for moderate dye loadings with a similar orientation angle around 30°. The presence of coplanar R6G H type dimers and high-order aggregates in moderate- and high-loading R6G/Lap films causes a depolarization for the fluorescence anisotropy of the J dimer, ascribed to an excitation energy-transfer process and reducing the applicability of this fluorescence method. However, present experimental results confirm a more-perpendicular disposition of these H aggregates with respect to the Lap layer. The new fluorescence polarization method can be extrapolated to determine the orientation of any adsorbed fluorophore in rigid and ordered 2D host materials.