Charge-separation in panchromatic, vertically positioned bis(donor styryl)BODIPY-aluminum(iii) porphyrin-fullerene supramolecular triads.

Three, broad band capturing, vertically aligned supramolecular triads, R2-BDP-AlPorF3←Im-C60 [R = H, styryl (C2H2-Ph), C2H2-TPA (TPA = triphenylamine); ← = coordinate bond], have been constructed using BODIPY derivative (BDP, BDP-Ph2 or BDP-TPA2), 5,10,15,20-tetrakis(3,4,5-trifluorophenyl)aluminum(iii) porphyrin (AlPorF3) and fullerene (C60) entities. The C60 and BDP units are bound to the Al center on the opposite faces of the porphyrin: the BDP derivative through a covalent axial bond using a benzoate spacer and the C60 through a coordination bond via an appended imidazole. Owing to the bis-styryl functionality on BDP, the constructed dyads and triads exhibited panchromatic light capture.

Triplet electron transfer and spin polarization in a palladium porphyrin-fullerene conjugate.

Transient electron paramagnetic resonance (TREPR) spectroscopy is used to investigate the pathway and dynamics of electron transfer in a palladium porphyrin-fullerene donor-acceptor conjugate. The heavy Pd atom in the porphyrin greatly enhances the rate of intersystem crossing and as a result, electron transfer from the porphyrin to fullerene occurs via the porphyrin triplet state. The sign of the polarization pattern of the radical pair generated by the electron transfer is opposite in benzonitrile and the liquid crystal 5CB.

Controlling electron and energy transfer paths by selective excitation in a zinc porphyrin-BODIPY-C multi-modular triad.

A multi-modular donor-acceptor triad composed of zinc porphyrin, BF-chelated dipyrromethene (BODIPY), and C was newly synthesized, with the BODIPY entity at the central position. Using absorbance and emission spectral, electrochemical redox, and computational optimization results, energy level diagrams for the ZnP-BODIPY dyad and ZnP-BODIPY-C triad were constructed to envision the different photochemical events upon selective excitation of the BODIPY and ZnP entities. By transient absorption spectral studies covering a wide femtosecond-to-millisecond time scale, evidence for the different photochemical events and their kinetic information was secured.

A High-Energy Charge-Separated State of 1.70 eV from a High-Potential Donor-Acceptor Dyad: A Catalyst for Energy-Demanding Photochemical Reactions.

A high potential donor-acceptor dyad composed of zinc porphyrin bearing three meso-pentafluorophenyl substituents covalently linked to C60 , as a novel dyad capable of generating charge-separated states of high energy (potential) has been developed. The calculated energy of the charge-separated state was found to be 1.70 eV, the highest reported for a covalently linked porphyrin-fullerene dyad.

Photoinduced charge separation in wide-band capturing, multi-modular bis(donor styryl)BODIPY-fullerene systems.

A new series of multi-modular donor-acceptor systems capable of exhibiting photoinduced charge separation have been designed, synthesized and characterized using various techniques. In this series, the electron donor was a BF2-chelated dipyrromethene (BODIPY) appended with two styryl linkers carrying two electron rich triphenylamine or phenothiazine entities. Fulleropyrrolidine linked at the meso-position of the BODIPY ring served as an electron acceptor.

Modulating the generation of long-lived charge separated states exclusively from the triplet excited states in palladium porphyrin-fullerene conjugates.

This study demonstrates molecular engineering of a series of donor-acceptor systems to allow control of the lifetime and initial spin multiplicity of the charge-separated state. By tuning the rate of intersystem crossing (ISC) and the donor-acceptor distance, electron transfer can be made to occur exclusively from the triplet excited state of the electron donor resulting in long-lived charge separation. To achieve this, three new palladium porphyrin-fullerene donor-acceptor systems were synthesized.

Tuning Interfacial Electron Transfer in Nanostructured Cuprous Oxide Photoelectrochemical Cells with Charge-Selective Molecular Coatings.

The coating of nanostructured films of cuprous oxide with electroactive molecules strongly affects their photoelectrochemical performance in nonaqueous photocells, with photocurrent density increased up to an order of magnitude relative to bare cuprous oxide films or almost completely suppressed, depending on the choice of molecular adsorbant. Among adsorbants that enhance photocurrent, a strong variance of photoelectrochemical behavior is observed with changes in the molecular structure of the sensitizer, associated with differences in the reorganization energy and molecular size, which are interpreted to enhance forward electron transport and impede electrolyte/photocathode recombination, respectively. These results demonstrate that nanostructured cuprous oxide is a promising cathode material for p-type dye-sensitized solar cells.