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The first donor-acceptor species in which a strongly emissive N-annulated perylene dye is connected to a methylviologen electron acceptor unit via its macrocyclic nitrogen atom, is prepared by a stepwise, modular procedure. The absorption spectra, redox behavior, spectroelectrochemistry and photophysical properties of this dyad and of its model species are investigated, also by pump-probe fs transient absorption spectroscopy. Photoinduced oxidative electron transfer from the excited state of the dyad, centered on the N-annulated perylene subunit, to the appended methyviologen electron acceptor takes place in a few ps. The charge-separated species recombines in 19 ps. Our results indicate that N-annulated perylene can be connected to functional units by taking advantage of the macrocyclic nitrogen, an option never used until now, without losing their properties, so opening the way to new designing approaches.

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We prepared a bichromophoric species 1, made of two different bodipy dyes bridged by a d-galactose unit. 1 exhibits different emission spectra when located in different compartments of biological systems, independently of its concentration. This is an unprecedented feature for a single multicomponent molecule and is due to the dependence on the environment of the photoinduced energy transfer process occurring between its bodipy subunits. Therefore, 1 can give useful information about cell composition and ultimately anomalies without requiring the simultaneous use of several different compounds, paving the way for the use of environment-controlled inter-component energy transfer to gain cell information based on luminescence imaging.

Two new tetralkylammonium-OPEs, bearing one or two positively charged groups directly linked to the aromatic residues and two β-d-glucopyranose terminations, were synthesized. Their peculiar structural features, joining the biologically relevant sugar moieties, flat aromatic cores and positive charges, make these luminescent dyes soluble in aqueous media and able to strongly interact with DNA. As a result of UV/Vis spectral variations, DNA melting temperature measures, viscometric titrations and induced CD, we propose a partial insertion of the OPEs aromatic core into the helix, stabilized by glucose H-bonding with the groups accessible from the grooves. This interaction leads to the quenching of the OPE luminescence due to guanine reduction. The biocompatibility of the monocationic OPE with healthy and cancer cells, and the reduction of proliferation in HEp-2 cancer cells induced by the dicationic one, make this class of compounds promising for future biological applications.