Donor-acceptor systems incorporating porphyrins

When amphiphilic dyes are incorporated into such monolayers, their fluorescence properties can be used to characterize the organization of the array [84-87]. An amphiphilic cyanine dye used in this way showed a much lower distance damping factor (P value) between layers containing the donor cyanine and the acceptor viologen (P = 0.3) than is usually observed in fixed donor-acceptor systems [88]. An even smaller p value was obtained from photocurrent measurements in monolayer assemblies containing amphiphilic porphyrins (p = 0.005) [89], The former value was attributed to electron tunnelling occurring in parallel... 

The construction of intramolecular molecular system whose photo active molecule linked with conducting molecular wire is an important subject in realization of. molecular electronic or photonic devices. For such objectives, systematization of donor-photosensitizer-acceptor triad molecules into large molecular systems is one of the feasible approaches because the exquisite incorporation of the photosensitizer and a suitable electron donor and/or acceptor into a conducting polymeric chain is useful for various molecular systems based on the photoinduced electron transfer. With this in mind, we synthesized symmetrical donor-acceptor-donor triad molecules which can be polymerized by the normal electrochemical oxidation. By the polymerization, one-dimensional donor-acceptor polymers with porphyrin moieties separated by ordered oligothienyl molecular wire which is considered as a proto-type molecular device was obtained. 

This section described the fabrication of ITO electrodes modified with porphyrin-terminated M(tpy)2 complex wires by the stepwise coordination method, and it is demonstrated that the electronic nature of the molecular wire is critical to the photoelectron transfer from the porphyrin to ITO. These results suggest that the new facile fabrication method of molecular assemblies is effective in the construction of photoelectron transfer systems. The system could be upgraded by extending the wire length, embedding the redox potential step in the wire, increasing the photoreceptors in the wire, and/or incorporating donors and acceptors. 

An alternative approach for the study of PCET across amidinium-carboxylate interfaces relies on the formation of ternary complexes such as that shown for 16 [141]. A N-propylisonicotinamidine serves as a ditopic spacer between a Zn tetra-phenylporphyrin donor and 3,4-dinitrobenzoate acceptor. The PCET assembly is afforded by the axial coordination of the pyridyl group to the Zn porphyrin (Ka = 1-9 X 10 M 2 in CH2CI2). A benefit of this approach is a significantly reduced synthetic investment required for the incorporation of Dp/Ap into the assembly. Moreover, the system is highly modular and the De porphyrin can be... 

---