An asymmetrical perylene diimide 3, N-（4-methoxyphenyl）-N＇-（4-nitrophenyl）-perylene-3,4,9,10-tetracarboxylic diimide, was synthesized, and its self-assembly and dissociation behaviors in chloroform was studied in detail by UV-vis and fluorescence spectroscopies. The resulting unique helical nanostructures from 3 were proposed to be self-assembled via the cooperative actions of π-π stacking, steric hindrance and electrophile-nucleophile type pairing.
Nanobelts, flower-like and rhizoid-like nanostructures of pure polyaniline （PANI） doped with sulfuric acid or hydrochloric acid were prepared via electrospinning by using a coagulation bath as the collector after optimizing the fabrication parameters. The morphologies of these nanostructures were characterized by scanning electron microscope （SEM）. The possible formation mechanisms were discussed.
We report that the ultraviolet （UV） light induced photochromic behavior of layered organic-inorganic perovskite material of （C4H9NH3）2CuCl4, changed from yellow to brown after irradiation with UV light （10 mW/cm^2） and partially recovered through storage in the dark. （C4H9NH3）2CuCl4 exhibited two distinct absorption bands centered at 286 nm （band Ⅰ） and 384 nm （band Ⅱ）, which were attributed to the photo-induced exciton formed in 2D inorganic layers sandwiched by organic layers. The blue shift of band Ⅰ from 287 to 269 nm as well as the decrease of the intensity of band Ⅰ and band Ⅱ could be found when samples were irradiated under UV light for different length of time. The simultaneous weakening of the intensity of the N-H...Cl hydrogen bond as well as the vibration of the long Cu-Cl bond in the distorted CuCl6^4- octahedron could be detected from the Fourier transform infrared （FTIR） spectra, which resulted the change of charge distribution of the dissymmetric Cl-Cu...Cl bond and the resulting photochromic behavior.
