RESUMO
New porphyrin sensitizers based on donor-π-acceptor (D-π-A) approach have been designed, synthesized, characterized by various spectroscopic techniques and their photovoltaic properties explored. N,N'-Diphenylamine acts as donor, the porphyrin is the π-spacer, and either carboxylic acid or cyanoacryclic acid acts as acceptor. All compounds were characterized by using (1)Hâ NMR spectroscopy, ESI-MS, UV-visible emission spectroscopies as well as electrochemical methods. The presence of aromatic groups between porphyrin π-plane and acceptor group push the absorption of both Soret and Q-bands of porphyrin towards the red region. The electrochemical properties suggests that LUMO of these sensitizers above the TiO2 conduction band. Finally, the device was fabricated using liquid redox electrolyte (I(-)/I3(-)) and its efficiency was compared with that of a leading sensitizer.
RESUMO
An efficient diastereoselective synthesis of brevipolide H derivative is described. The approach features the use of (i) catalytic asymmetric transfer hydrogenation, (ii) hydroxyl-directed cyclopropanation, and (iii) substrate-controlled catalytic epoxidation and ring-closing metathesis. Remarkably, in this convergent synthesis process, stereogenic centers were installed through catalytic reactions with high stereocontrol, which greatly facilitates the synthesis of stereo-divergent derivatives.