Subphthalocyanine-spiropyran - a versatile system to study photoswitchable fluorescence

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Fluorescence is a – sometimes unwanted – property of conjugated pi systems that form the basis for all materials that are used in organic electronics. Precise control of a material’s luminescence can be utilized in optical memory devices. This can be achieved by bringing a photochrome into the proximity of the fluorophore. Switching the photochromic moiety can quench the emission of the fluorophore.This project utilizes spiropyran as photochrome to influence the emission properties of boron subphthalocyanines (SubPcs). SubPcs were applied in organic photovoltaics or light emitting diods. The combination with spiropyrans provides the possibility to study the influence of the photoswitch on the SubPc’s emission. At the SubPc, two different linking geometries to three distinct sites of the spiropyran are feasible. Beside energy transfer through close distances, spiropyran can directly influence the aromatic system in SubPcs. Depending on the linking site, spiropyran acts either as electron donor or acceptor, or is decoupled from the pi system of SubPc. After an electrocyclic ring opening to the merocyanine form, these electronic influences are reversed. With these versatile building blocks, it will be possible to design and study systems that act as ON/OFF or OFF/ON photoswitchable fluorophore.