Coupled photosensitized

Two cobalt cage complexes with covalently linked anthracene chromophore (Scheme 124) have been studied as coupled photosensitizers (anthracene substituent) and electron relays (cage fragment) to produce hydrogen [305]. 

In another reductive coupling, substituted alkenes (CH2=CH Y Y = R, COOMe, OAc, CN, etc.) can be dimerized to substituted alkanes (CH3CHYCHYCH3) by photolysis in an H2 atmosphere, using Hg as a photosensitizer. Still another procedure involves palladium-catalyzed addition of vinylic halides to triple bonds to give 1,3-dienes. ... 

Nasr C, Hotchandani S, Kim WY, Schmehl RH, Kamat PV (1997) Photoelectrochemistry of composite semiconductor thin films. Photosensitization of Sn02/CdS coupled nanocrystal-Utes with a ruthenium polypyridyl complex. J Phys Chem B 101 7480-7487... 

In plants, the photosynthesis reaction takes place in specialized organelles termed chloroplasts. The chloroplasts are bounded in a two-membrane envelope with an additional third internal membrane called thylakoid membrane. This thylakoid membrane is a highly folded structure, which encloses a distinct compartment called thylakoid lumen. The chlorophyll found in chloroplasts is bound to the protein in the thylakoid membrane. The major photosensitive molecules in plants are the chlorophylls chlorophyll a and chlorophyll b. They are coupled through electron transfer chains to other molecules that act as electron carriers. Structures of chlorophyll a, chlorophyll b, and pheophytin a are shown in Figure 7.9. 

Recently a new hybrid power source has been reported that couples oxidation at a dye-photosensitized nanocrystalline semiconducting SnOz photoanode with the enzyme-catalyzed reduction of O2. Although miniaturization has not yet been reported for this new hybrid, the developments already achieved to miniaturize biofuel cells coupled to those being developed for charge-insertion oxides should be technically transferable to this system. 

Most phthalocyanines show inferior dark decay to azo pigments, an exception being the titanyl phthalocyanines, where in the best cases, e.g. the a- and Y- forms, they show comparable dark decay coupled with superior photosensitivity. A comparison of the sensitivity of azo pigments and selected polymorphs of phthalocyanines is shown graphically in Figure 4.12. 

Hao W, Fong HK 1999 The endogenous chromophore of retinal G protein-coupled receptor opsin from the pigment epithehum. J Biol Chem 274 6085—6090 Hattar S, Liao HW, Takao M, Berson DM, Yau KW 2002 Melanopsin-containing retinal ganglion cells architecture, projections, and intrinsic photosensitivity. Science 295 1065— 1070... 

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