Donor-Acceptor Heterojunction Configurations Based on DNA-Multichromophore Arrays.

Multichromophore arrays of bis(2-thienyl)diketopyrrolopyrrole (DPP) and naphthalenediimide (NDI) with two Zn(II) -cyclens were constructed using thymidine DNA as a scaffold through the binding of the Zn(II) -cyclens with thymine bases. We demonstrate photocurrent generation in a donor-acceptor heterojunction configuration consisting of the DPP (donor) and NDI (acceptor) arrays co-immobilized on an Au electrode. The co-immobilized electrode exhibited good photocurrent responses because of the efficient charge separation between the DPP and NDI arrays. In contrast, an immobilized electrode consisting of randomly assembled DPP-NDI arrays generated no photocurrent response because DPP formed ground-state charge-transfer complexes with NDI in the randomly assembled arrays. Therefore, our approach to generate donor-acceptor heterojunctions based on DNA-multichromophore arrays is a useful method to efficiently generate photocurrent.

Diketopyrrolopyrrole j-aggregates formed by self-organization with DNA.

Bis(2-thienyl)diketopyrrolopyrrole with two Zn(II)-cyclens (ZnCyc-DPP) was designed and synthesized to evaluate the selective binding of Zn(II)-cyclen with thymine base in single-strand DNA as a tool for the construction of a highly ordered multichromophore system on DNAs. Through UV/Vis titrations, gel filtration chromatography, and circular dichroism spectroscopy, ZnCyc-DPP formed J-type DPP aggregates with oligo-dTn DNAs. The DPP aggregates absorbed on a gold electrode exhibited good photocurrent responses. The present results show that binding Zn(II)-cyclen-chromophore conjugates and thymine bases together is a powerful tool for preparing DNA-templated multichromophoric systems with specific functions.