Stepwise photochemical-chiral delivery in gamma-cyclodextrin-directed enantioselective photocyclodimerization of methyl 3-methoxyl-2-naphthoate in aqueous solution.

Irradiation of methyl 3-methoxyl-2-naphthoate (2,3-NA) with lambda > 280 nm results in photocyclodimerization to produce cubane-like photocyclodimer 1 and the [4 + 4] intermediate 2. The optically pure enantiomers of the intermediate 2 have been achieved by high-performance liquid chromatography (HPLC) resolution on a chiralcel OJ-RH column. Comparison of the enantiomeric excess (ee) values for photocyclodimer 1 and the intermediate 2 obtained in gamma-CD aqueous solution reveals the stepwise photochemical-chiral delivery for the first time, which is recognized to be a consequence of an in situ increase in the ee value from 39% for the [4 + 4] intermediate 2 to 48% for photocyclodimer 1 upon irradiation of 2,3-NA in the presence of gamma-CD.

Photoinduced triplet-triplet energy transfer via the 2-ureido-4[1H]-pyrimidinone self-complementary quadruple hydrogen-bonded module.

Phosphorescence quenching and flash photolysis experiments demonstrate that photoinduced intra-assembly triplet-triplet energy transfer can take place via a 2-ureido-4[1H]-pyrimidinone-bridged benzophenone-naphthalene assembly I with a rate constant of 3.0 x 106 s-1 and an efficiency of 95% in CH2Cl2. This new finding suggests that with high binding strength and directionality, the 2-ureido-4[1H]-pyrimidinone hydrogen-bonded module may serve as a new model to illustrate the fundamental principles governing the triplet-triplet energy-transfer process through hydrogen bonds.

Synthesis, spectroscopic, electrochemical and Pb2+-binding studies of tetrathiafulvalene acetylene derivatives.

A series of tetrathiafulvalene acetylene derivatives, [TTF-Ctriple bondC-A] [A=C6H4N(CH3)2-4 (1), C6H4OCH3-4 (2), C6H5 (3), C6H4F-4 (4), C6H4NO2-4 (5), C5H4N-2 (6), C5H4N-3 (7), and C5H4N-4 (8)], have been designed and synthesized to provide insight into the nature of the donor-acceptor interaction via a pi-conjugated triple bond. The X-ray crystal structure of [TTF-(Ctriple bondC)-C6H4OCH3-4] (2) reveals that the phenyl ring linked by acetylene is almost coplanar to the plane of TTF with a dihedral angle of 3.6 degrees.

Photooxidation of olefins under oxygen in platinum(II) complex-loaded mesoporous molecular sieves.

Cyclometalated platinum(II) complex has been successfully incorporated into the (3-aminopropyl) triethoxysilane-modified channels of ordered mesoporous silica SBA-15 that has large pore hexagonal channels. Studies on the (1)O(2) generation conclusively demonstrates that the olefins in the nano-channels of SBA-15 can be enriched 8 times higher than those in the homogeneous solution as the diffusion quantum yield of singlet oxygen ((1)O(2)) is assumed to be unit. The platinum(II) complex loaded in the channel of SBA-15 is stable, and the photosensitized oxidation occurs efficiently.