D-π-A Structured Porphyrin and Organic Dyes with Easily Synthesizable Donor Units for Low-Cost and Efficient Dye-Sensitized Solar Cells.

This study aimed to develop low-cost D-π-A structured porphyrin and organic dyes with easily synthesizable donor units instead of the conventional complex multistep synthetic donor unit of [bis(7-(2,4-bis(hexyloxy)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)amine] used in and as well-known record cosensitizers with an extremely high power conversion efficiency (PCE). The design strategy concerned the easier synthesis of low-cost donor units with inversion structures in donor groups via donor structural engineering, particularly by changing the position of the fluorene and phenylene units in the donor moiety while keeping the π-bridge and acceptor unit unchanged, leading to the synthesis of two D-π-A structured porphyrins [ and ] and one D-π-A structured organic sensitizer [] for dye-sensitized solar cells (DSSCs). Specifically, porphyrin incorporated two hexyl chains into the 9-position of each fluorene, while and substituted two hexyloxy chain units to the terminal position of each fluorene in the donor groups of porphyrin dyes.

Electrostatic Modification for Promotion of Flavin-Mediated Oxidation of a Probe for Flavin Detection.

Electrostatic effects on the redox photochemistry of synthetic probes (1, 2, and 1-Zn) are examined by adjusting the thermodynamic driving force of their oxidation reactions. The redox photochemistry was simply controlled by introducing a zinc binding site (2,2'-dipicolylamine (DPA)) on the coumarin moiety of probe 2. Zinc complexation produced a positively charged environment on the coumarin (1-Zn), which lowered the electron density of a nearby 9 H-xanthene ring, attenuating the auto-oxidation of 1-Zn by 45 % compared with that of probe 1 at 298 K.

Flavin-mediated photo-oxidation for the detection of mitochondrial flavins.

We report a new approach for the detection of mitochondrial flavins through photo-oxidation of a probe molecule. Probe 1 showed high brightness (ε × Φ = 6.50 × 10 M cm) at long wavelengths (maximum emission wavelength, λ = 600 nm) upon photo-oxidation, assisted by the strong electron accepting ability of the isoalloxazine moiety in flavins.

Electronic effect on the kinetics of the diaza-cope rearrangement.

Hammett plot reveals that there is a significant electronic effect on the rate of resonance assisted hydrogen bond (RAHB) directed diaza-Cope rearrangement reaction with a rho value of 1.6. DFT computation shows that the rearrangement reaction becomes thermodynamically more favorable for the substrates with electron withdrawing substituents.