Photoelectrochemical Reactions at Phthalocyanine Electrodes

Schlettwein, Derck

doi:10.1007/978-0-387-28430-9_10

Cited by 3 publications

(1 citation statement)

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“…Phthalocyanines (Pcs) have been studied extensively because of their applications in photonics, [1][2][3] data storage, 4 photocatalysis, [5][6][7][8] photodynamic therapy, 9,10 and solar energy conversion. 11,12 Optical properties of Pcs can be controlled and manipulated through binding different metal ions with various axial ligands, and covalently attaching different side groups. [13][14][15] In particular, Pcs self-assemble into nanometer scaled aggregates via nonbonding interactions, such as π-stacking, in films, liquid crystals, and solutions, and such stacking can be controlled via chemical modifications.…”

Section: Introductionmentioning

confidence: 99%

Excited State Dynamics and Structures of Functionalized Phthalocyanines. 1. Self-Regulated Assembly of Zinc Helicenocyanine

et al. 2005

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Recently synthesized zinc helicenocyanine (ZnHc), where four helicene groups are fused with a phthalocyanine (Pc) core through all-carbon linkages, exhibits an unusually strong tendency of forming soluble molecular aggregates in organic solvents. The aggregation results in a strong optical absorption across most of the visible region, which is drastically different from that of its monomer. The aggregation is suppressed by dissolving ZnHc in a liquid crystal, octylbiphenylcarbonitrile (OBCN), where the monomer ZnHc dominates and exhibits a typical optical absorption spectrum of monomeric zinc phthalocyanine, except red shift in both Q- and B- bands due to pi-conjugation expansion. This study correlates optical properties and excited state dynamics of ZnHc with intra- and intermolecular electronic interactions, using quantum mechanical calculations and ultrafast transient absorption spectroscopy. Structural details of the aggregates are revealed by small-angle X-ray scattering (SAXS) to be uniformly dimers with alkoxy chains wrapped around the core of a face-to-face dimer. The results suggest that while the peripheral helicene moieties in ZnHc are electronically coupled to the Pc core via expansion of the pi-conjugation of the macrocycle, the coupling is attenuated by the "lock washer" conformation of the nonplanar peripheral helicenes which prevents pi-conjugation throughout the entire macrocycle. The interplay between pi-conjugation expansion in the macrocyle plane and the pi-pi stacking out of the macrocyle plane produces a structure that facilitates the unique optical properties and self-regulated assembly into nanoscale structures in solution. These novel optical properties are explored for potential applications in various areas.

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