A novel dyad composed of a diaminoterephthalate scaffold, covalently linked to a fullerene derivative, is explored as a nanosized charge separation unit powered by solar energy. Its opto‐electronic properties are studied and the charge separation rate is determined. Simulations of the coupled electronic and nuclear dynamics in the Ehrenfest approximation are carried out on a sub 100 fs time scale after photoexcitation in order to gain insights about the mechanisms driving the charge separation. In particular, the role of vibronic coupling and of the detailed morphology are highlighted.

The fluorescent diaminoterephthalate scaffold was equipped by amidation with three types of reactive functions: thiols for metal-surface binding, alkynes for click reactions, and maleimides for ligation with proteins. Starting from a succinyl succinate derivative with two orthogonally cleavable ester functions, three monoamides (38-57% yield over three steps) and two bisamides (19 and 25% yield over five steps) were prepared. Although alkyne and thiol derivatized compounds showed reasonable luminescence behavior (Φ≈1-4%), the fluorescence was quenched by the maleimide moiety. It was turned on (10- to 20-fold increase of fluorescence quantum yield) by conjugate addition of thiols.

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Diaminoterephthalate was used for the first time as a chromophore in a dyad with [60]fullerene. The synthesis was accomplished from the benzyl methyl diester by hydrogenolytic cleavage of the benzyl group, re-esterification with a benzyl alcohol with protected formyl function, deprotection of the latter and final 1,3-dipolar cycloaddition with C 60 and sarcosine via the azomethine ylide.In order to mimic natural photosynthesis and to understand fundamental photoinduced electron and energy transfer processes, many photosynthetic models have been constructed and investigated in the past few decades. 1 Among the energy-and electron-accepting moieties, fullerene (C 60 ) has become the most promising one due to its unique physical and chemical properties. For example it can be easily ligated to dyes and other larger molecular entities by cycloaddition reactions. Several dye-fullerene conjugates, so called dyads, have been prepared in the past years. 2 We have recently prepared and investigated a related compound, a triad consisting of a carotenoid as electrondonating, C 60 as electron-accepting moieties, and a porphyrin derivative as the central chromophore. 3 The multistep, low-yielding synthesis of this compound was quite a challenge, 4 which is mainly attributed to the construction and two-fold unsymmetric derivatization of the porphyrin core. Therefore, a more straightforward synthetic route to a dyefullerene conjugate was pursued and a diaminoterephthalate derivative was selected as the chromophore. We have recently introduced diaminoterephthalates as colored molecular scaffolds bearing up to four sites for orthogonal functionalization. 5 Furthermore, diaminoterephthalates show promising fluorescence properties, 6 which can bewith prerequisite functionalization -switched on by a chemical reaction and can therefore be used as 'turn-on' probes for biochemical applications. 7 In particular, we suggested dyad 6 as a distinguished molecular model for spectroscopic investigations of electron transfer processes on a femtosecond timescale. Prior to synthesis, computational studies on compound 6 were performed, which allowed us to attribute the absorption edge to a predominant pure transition between the highest occupied and the lowest unoccupied molecular orbitals, and to identify two distinct channels for electron transfer reactions in the dyad, namely one involving an indirect exciton and one attributed to a phonon-mediated mechanism driving an initial excitation of direct excitonic character. 8 We now report herein the optimized synthesis of compound 6, which is the first example of a diaminoterephthalate as chromophore in dyads for optoelectronic applications.