Zinc-porphyrin phosphonate coordination: structural control through a zinc phosphoryl-oxygen interaction.

Inter- and intramolecular zinc-porphyrin phosphonate coordination in the cis and trans isomers of zinc tetraphenylporphyrinstyryldiphosphonate is reported, demonstrating the potential of the zinc phosphoryl-oxygen interaction for structural control.

Towards functionalized poly(terthiophenes): regioselective synthesis of oligoether-substituted bis(styryl)sexithiophenes.

A variety of new bis(oligo(oxyethylene)styryl)sexithiophenes have been prepared by chemical oxidation of ether-substituted styrylterthiophenes with FeCl3. In all cases dimers are formed in high yields, rather than the expected polymers. In addition, although three different regioisomers can potentially be formed from such an oxidation, the isolable products are shown to consist of only the head-to-head regioisomer. Theoretical calculations on alkoxystyrylterthiophenes show that this can be understood in terms of an uneven electron spin density distribution at the two alpha-positions available for polymerization. Electron density calculations on the resulting head-to-head alkoxystyrylsexithiophenes show that the spin density is concentrated in the core of the molecule rather than at the alpha-positions, a result that explains the absence of significant amounts of higher oligomers.

Efficient light harvesting by using green Zn-porphyrin-sensitized nanocrystalline TiO2 films.

A series of novel zinc metalloporphyrins, cyano-3-(2'-(5',10',15',20'-tetraphenylporphyrinato zinc(II))yl)-acrylic acid (Zn-3), 3-(trans-2'-(5',10',15',20'-tetraphenylporphyrinato zinc(II))yl)-acrylic acid (Zn-5), 2-cyano-5-(2'-(5',10',15',20'-tetraphenylporphyrinato zinc(II))yl)-penta-2,4-dienoic acid (Zn-8), 4-(trans-2'-(2' '-(5' ',10' ',15' ',20' '-tetraphenylporphyrinato zinc(II))yl)ethen-1'-yl))-1,2-benzenedicarboxylic acid (Zn-11), and 2-cyano-3-[4'-(trans-2' '-(2' ''-(5' '',10' '',15' '',20' ''-tetraphenylporphyrinato zinc(II))yl) ethen-1' '-yl)-phenyl]-acrylic acid (Zn-13) were synthesized and characterized by using various spectroscopic techniques. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations show that key molecular orbitals (MOs) of porphyrins Zn-5 and Zn-3 are stabilized and extended out onto the substituent by pi-conjugation, causing enhancement and red shifts of visible transitions and increasing the possibility of electron transfer from the substituent. The porphyrins were investigated for conversion of sunlight into electricity by constructing dye-sensitized TiO(2) solar cells using an I(-)/I(3)(-) electrolyte. The cells yield close to 85% incident photon-to-current efficiencies (IPCEs), and under standard AM 1.5 sunlight, the Zn-3-sensitized solar cell demonstrates a short circuit photocurrent density of 13.0 +/- 0.5 mA/cm(2), an open-circuit voltage of 610 +/- 50 mV, and a fill factor of 0.70 +/- 0.03. This corresponds to an overall conversion efficiency of 5.6%, making it the most efficient porphyrin-sensitized solar cell reported to date.