Synthesis and Photophysical Properties of Multichromophoric Carbonyl-Bridged Triarylamines

The synthesis and photophysical properties of two novel multichromophoric compounds is presented. Their molecular design comprises a carbonyl‐bridged triarylamine core and either naphthalimides or 4‐(5‐hexyl‐2,2′‐bithiophene)naphthalimides as second chromophore in the periphery. The lateral chromophores are attached to the core via an amide linkage and a short alkyl spacer. The synthetic approach demonstrates a straightforward functionalization strategy for carbonyl‐bridged triarylamines. Steady‐state and time‐resolved spectroscopic investigations of these compounds, in combination with three reference compounds, provide clear evidence for energy transfer in both multichromophoric compounds. The direction of the energy transfer depends on the lateral chromophore used. Furthermore, the compound bearing the lateral 4‐(bithiophene)naphthaimides is capable of forming fluorescent gels at very low concentrations in the sub‐millimolar regime whilst retaining its energy transfer properties. There and back again: Two multichromophoric bridged triarylamines are presented that are functionalized in a straightforward synthetic approach with either three naphthalimides or three 4‐(bithiophene)naphthalimides. Efficient energy transfer is observed in both compounds (see figure). In the first case, the energy is funneled from the peripheral naphthalimides, acting as antenna dyes, to the core. In the second, the energy is transferred from the core to the periphery.