Photoinduced Charge Separation in a Donor–Spacer– Acceptor Dyad with N-Annulated Perylene Donor and Methylviologen Acceptor Marie-Pierre Santoni,* Antonio Santoro, Tania M. G. Salerno, Fausto Puntoriero,* Francesco Nastasi, M. Letizia Di Pietro, Maurilio Galletta, and Sebastiano Campagna* [a] 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 pre- pared by a stepwise, modular procedure. The absorption spec- tra, redox behavior, spectroelectrochemistry and photophysical properties of this dyad and of its model species are investigat- ed, 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 subu- nit, 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 mac- rocyclic nitrogen, an option never used until now, without losing their properties, so opening the way to new designing approaches. The search for new highly luminescent species is a very attrac- tive field for several reasons, including the development of new dyes for 1) fluorescence imaging dealing with the bio- chemical and medical realms, [1] 2) light-emitting dyad systems for illumination, [2] and 3) design of new dye-sensitized solar cells (DSCs). [3, 4] In recent years, a new class of dyes exhibiting quite intense and tunable luminescence has been identified, namely N-annulated perylenes (NAPs). [5] Indeed, NAP species exhibit strong visible absorption, efficient photoluminescence, and redox reversibility, all properties that are also largely tuna- ble (e.g. strong absorption up to 700 nm can be obtained), in- troducing substituents at the peri-position near the amine site. [6] Actually, NAPs have recently been exploited as part of multicomponent systems within the field of DSCs, taking ad- vantage of both their absorption properties and reversible oxi- dation behavior. [7] To our knowledge, in all the reported cases the NAP dye has been connected to the other subunits of the multicomponent systems (other light absorbers or electron ac- ceptor mediators, in their turn linked to the metal oxide semi- conductor electrode) by a substitution at the peri-position of the macrocyclic nitrogen. Connection via the nitrogen atom of the N-annulated cycle to other photo- and/or redox-active sub- units (including metal oxide semiconductor surfaces) has not been explored. In fact, substitution at the nitrogen atom has only been used to improve solubility of NAP species, but not to attach functional (e.g., photo- and/or redox-active) subunits. Here we report the first example of a donor-bridge-acceptor dyad, 1 (see structural formula in Figure 1) in which the donor is an N-annulated perylene, connected to the bridge-acceptor subunits via the nitrogen of the macrocyclic structure, and show its absorption spectra, redox behavior, and photophysical properties, including ultrafast photoinduced charge separation and recombination. Our results indicate that the N-annulated perylenes can conveniently be connected via the nitrogen atom to other subunits for photoinduced processes, without losing their properties, thus offering new ways to molecular design of multicomponent systems suitable for light-powered functions. Noteworthy, the peri-positions of NAP species are therefore available for further substitution (e.g., to incorporate other functional subunits) or tunability reasons. The synthetic, modular approach is shown in Figure 1. The N-annulated perylene dye obtained via step b [8] is reacted with a,a’-dibromo-p-xylene (step c) to yield the Br-substituted spe- cies in which the NAP chromophore is connected to a phenyl- Figure 1. Structural formulae and modular synthetic pathway and reaction conditions for 1 and 2 : a) 1,4-dioxane/water/HNO 3 (24/9/6), reflux, 1 h; b) P(OEt) 3 ,N 2 , reflux, 2 h; c) a,a’-dibromo-p-xylene (3.8 equiv), KOH (1.5 equiv), KI (0.05 equiv), THF, N 2 , reflux, 48 h; d) methyl-4,4’-bipyridinium hexafluorophosphate (1 equiv), MeCN, N 2 , reflux, 12 h, NH 4 PF 6 ; e) bromoben- zyl (3 equiv), KOH (4 equiv), KI (0.12 equiv), THF, N 2 , reflux, 26 h. Full details in the Supporting Information. [a] Dr. M.-P. Santoni, A. Santoro, T. M.G. Salerno, Prof. F. Puntoriero, Dr. F. Nastasi, Dr. M. L. Di Pietro, Dr. M. Galletta, Prof. S. Campagna Dipartimento di Scienze Chimiche Università di Messina and Centro Interuniversitario per la Conversione Chimica dell’Energia Solare (SOLARCHEM, Sezione di Messina) Via F. Stagno d’Alcontres 31 Messina (Italy) E-mail : mpcc.santoni@gmail.com fpuntoriero@unime.it campagna@unime.it Supporting Information for this article is available on the WWW under http://dx.doi.org/10.1002/cphc.201500615. ChemPhysChem 2015, 16, 3147 – 3150 # 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 3147 Communications DOI: 10.1002/cphc.201500615