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A series of optically active methacrylic homopolymers, poly[(4‐{4′‐[(S)‐2‐methyl‐1‐butyloxycarbonyl]phenylazo}phenoxyl)x‐methylene methacrylate] (x = 0, 2, 6, or 11), were synthesized. The structures of the polymers were characterized by IR, 1H NMR, UV, differential scanning calorimetry, and gel permeation chromatography. The chiroptical properties of the polymers in films were investigated with circular dichroism (CD) measurements. The CD and UV spectra of the films suggested that CD absorptions occurred in the films of the polymers with long spacers (x = 6 or 11) but not in the films of the polymers with short spacers (x = 0 or 2). After irradiation with linearly polarized light at 442 nm, the CD values were amplified in all the polymeric films. The amplificatory values of the CD bands in the absorption region (260–360 nm) of azobenzene chromophores suggested that the spacer length had an effect on both the transfer of chirality and photoinduced chirality in the polymeric films. The largest level of photoinduced chirality was induced in the polymer containing six methylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3210–3219, 2006

The photovoltaic properties of YBa2Cu3O7−δ/Nb-doped SrTiO3 (SNTO) heterostructures were investigated systematically under laser irradiation of different wavelengths from 365 nm to 640 nm. A clear photovoltaic effect was observed, and the photovoltage Voc ranged from 0.1 V to 0.9 V depending on the wavelength. The Voc appeared under laser illumination with a photon energy of 2.4 eV, far below the band gap (3.2 eV) of Nb-doped SrTiO3. The temperature dependencies of the Voc and short-current density showed kinks near the structural phase transition of the Nb-doped SrTiO3. Our findings are helpful for understanding the photovoltaic effect in transition-metal oxide based heterojunctions and designing such photovoltaic devices.

A series of new liquid crystalline copolymers, poly[((S)‐2‐methyl‐1‐butyl methacrylate)‐co‐(6‐(4‐(4‐cyanophenylazo)phenoxy)hexyl methacrylate)], with different contents of chiral units of 17, 36, 54 and 78 mol% were synthesized. The structures and properties of the copolymers were characterized and evaluated using infrared, 1H NMR and UV spectroscopy, differential scanning calorimetry, gel permeation chromatography and circular dichroism (CD). The CD results suggested that absorptions of azobenzene chromophores were observed in films of copolymer containing 17, 36 or 54 mol% chiral units, but not in the film of copolymer containing 78 mol% chiral units. Also, CD values of the copolymeric films decreased with increasing chiral content. After irradiation with linear polarized light at 442 nm, CD values were changed in all the copolymeric films, and the CD values increased with decreasing chiral content in a nonlinear way, while the photoinduced change of chirality of the copolymers increased in a linear way with decreasing chiral content. The results are discussed in terms of interactions between structures and chiroptical properties. Copyright © 2007 Society of Chemical Industry