A carotenoid (C) porphyrin (P) fullerene (C 60 ) molecular triad (C-P-C 60 ) has been synthesized and found to undergo photoinduced electron transfer from the porphyrin first excited singlet state or to the fullerene first excited singlet state to yield C-P •+ -C 60 •-. Electron transfer from the carotenoid then gives a C •+ -P-C 60 •final charge-separated state. This state is formed with quantum yields up to 0.88 and has a lifetime of up to 1 µs, depending upon the conditions. The various electron transfer rate constants are relatively insensitive to solvent and temperature. The quantum yield of C •+ -P-C 60 •is relatively constant under conditions ranging from fluid solutions at ambient temperatures to a rigid organic glass at 8 K. In most solvents, recombination of C •+ -P-C 60 •yields the carotenoid triplet state, rather than the ground state. The results suggest that the energies of the charge-separated states of fullerene-based systems are only about half as sensitive to changes in solvent dielectric constant as are those for similar molecules with quinone electron acceptors, and that total reorganization energies for electron transfer are also smaller.

A conducting atomic force microscope was used to measure the electrical properties of carotenoid molecules attached to a gold electrode. The thiolated carotene molecules were embedded in insulating n-alkanethiol self-assembled monolayers. At a contact force of a few nanoNewtons, a carotenoid molecule behaves ohmically with a resistance of approximately 4.2 ± 0.7 GΩ, over a million times more conductive than an alkane chain of similar length. Modes of electron transport are discussed.

A pressurized electrochemical system equipped for continuous reduction of CO 2 is presented. At elevated pressures, using a Ag-based cathode, the quantity of CO which can be generated is 5 times that observed at ambient pressure with faradaic efficiencies as high as 92% observed at 350 mA cm −2 . For operation at 225 mA cm −2 and 60 • C the cell voltage at 18.5 atm was 0.4 V below that observed at ambient pressure. Increasing the temperature further to 90 • C led to a cell voltage below 3 V (18.5 atm and 90 • C), which equates to an electrical efficiency of 50%.

meso-Polyarylporphyrins are often used as components of molecules that mimic photosynthetic reaction centers by carrying out photoinduced electron-transfer reactions. Studies of these systems have raised questions concerning the role of alkyl substituents at the "β-pyrrolic" positions on the porphyrin periphery in limiting π-π overlap between the macrocycle and the aryl rings. The degree of overlap affects electronic coupling and, therefore, the rates of electron-transfer reactions. There is also evidence that when the linkages joining porphyrins to electron-acceptor or -donor moieties contain amide bonds, the sense of the amide linkage may strongly affect electron-transfer rate constants. In this study, three carotenoid-porphyrin-quinone molecular triads and various model compounds have been prepared, and electron-transfer has been studied using timeresolved emission and absorption techniques. The results show that steric hindrance due to methyl groups at the β-pyrrolic positions reduces electron-transfer rate constants by a factor of ∼ 1 / 5 . In addition, amidecontaining donor-acceptor linkages having the nitrogen atom attached to the porphyrin meso-aryl ring demonstrate electron-transfer rate constants ∼30 times larger than those for similar linkages with the amide reversed, after correction for thermodynamic effects.

Background-Islet transplantation is a promising treatment for type 1 diabetes. Due to a shortage of suitable human pancreata, high cost, and the large dose of islets presently required for long-term diabetes reversal; it is important to maximize viable islet yield. Traditional methods of pancreas preservation have been identified as suboptimal due to insufficient oxygenation. Enhanced oxygen delivery is a key area of improvement. In this paper, we explored improved oxygen delivery by persufflation (PSF), ie, vascular gas perfusion.