An amphiphilic barbituric acid derivative was found to form stable monolayers showing a clear phase transition at the air/water interface. It is interesting to find that the deposited Langmuir-Blodgett (LB) films of the compound showed circular dichroism (CD) although the molecule itself was achiral. AFM measurements on the transferred one-layer LB film revealed that spiral nanoarchitectures were formed. It was further found that the supramolecular chirality of the LB films was related to symmetry breaking at the interface. Hydrogen bonding and the pi-pi stacking between the neighboring molecules resulted in chiral fibers which formed the spiral structures. To the best of our knowledge, this is the first report on the chirality of the molecular assemblies and spiral nanostructures formed through the air/water interface by achiral molecules.

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A photoelectrochemical solar cell based on porous ZnO-covered TiO 2 film has been fabricated with ruthenium bipyridyl complex as the sensitizer. The cell generated a shortcircuit photocurrent of 21.3 mA cm -2 and an open-circuit voltage of 712 mV under irradiation of 81.0 mW cm -2 white light from a xenon lamp with an overall conversion efficiency of 9.8%. Compared with the pure TiO 2 (anatase) film, the ZnO-covered TiO 2 film possesses more outstanding ability to transport electrons with an overall power conversion efficiency increase by 27.3%. Optical elctrochemical studies show that surface modification of TiO 2 with ZnO can increase the concentration of free electrons in the conduction band of TiO 2 . This result implies that the charge recombination is reduced in the process of electron transport through the porous network, which can decrease the photocurrent loss and hence improve both short-circuit photocurrent and open-circuit photovoltage.