A water-soluble, 'turn-on' fluorescent chemosensor based on aggregation-induced emission (AIE) has been developed. It exhibits rapid response, excellent selectivity, and sensitivity to Al(3+).

The relationship between the structures and light emission properties of five aryl-substituted pyrrole derivatives was studied during aggregation in THF-water mixtures. Only pentaphenylpyrrole clearly shows, however, an aggregation-induced emission enhancement (AIEE) phenomenon. On comparison of the optical properties and single-crystal structures of these pyrrole derivatives, it is suggested that the more twisted configuration which prevented parallel orientation of conjugated chromophores combined with the restricted intramolecular rotation (RIR) effect was the main cause of the AIEE phenomenon.

This article describes for the first time the direct observation of the nucleation and growth process of CdS nanowires in a typical vapor−solid synthetic route. Thermal evaporating of CdS nanosized powders at 1173 K for various time durations corresponds to different growth stages and leads to varied product morphologies. Initially, CdS appeared as amorphous spherical particles, followed by nucleation of nanorods from cusps on the particle surface. Subsequently, nanorods developed to nanowires with matrix particles being consumed. Strategies could be optimized to grow CdS nanowires of varied diameters and lengths for a variety of applications.

Whereas aggregation often quenches luminescence, the emission of a heterocyclic luminogen, 10-[2,5-bis(4-pentyloxyphenylcarbonyloxy)phenyl]-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (3), is greatly enhanced by aggregate formation. Crystallization further boosts the emission of 3, turning it from a weak emitter in the solution state to a strong emitter in the crystalline state. The emission of 3 is changed in response to the exposure to vapors of volatile organic compounds (VOCs). The morphology of the thin film of 3 is reversibly and repeatedly modulated between amorphous and crystalline phases by simple fuming-heating and heating-cooling cycles, leading to an emission switching between bright and dark states. The novel attributes of the crystallization-induced emission enhancement, the VOC-responsive emission change, and the morphology-tunable emission switching of 3 could enable it to find applications in an array of technological areas, including chemosensing, optical display, and rewritable information storage.

In this work, X‐ray diffractometry and scanning electron microscopy techniques were used to study the incorporation of yttrium in BaTiO3, with the following nominal compositions: (Ba1‐xYx)TiO3(0.015 ≤ to x≤ to 0.08), (Ba1‐xYx)Ti1‐x/4‐(□Ti)x/4O3(0.005 ≤ to x≤ to 0.1), and Ba(Ti1‐yYy)O3‐delta(0.028 ≤ to y≤ to 0.258). The phase assemblage and the lattice parameters indicated a slight solubility (∼1.5 at.%) of yttrium at the Ba sites at 1440°C but a high solubility (∼12.2 at.%) of yttrium at the Ti sites at 1515°C. When BaTiO3was heavily doped with yttrium at the Ti sites (a yttrium concentration (y) of <0.059), the crystallographic structure was tetragonal, whereas for y greater than equal to 0.059, the crystallographic structure was cubic.

A novel full-conjugated 4-(2,2′:6′,2′′-terpyrid-4′-yl) benzenediazonium tetrafluoroborate (diazo-tpy) was synthesized and used for surface modification of materials, such as quartz wafers, ITO glass, silicon, and multiwalled carbon nanotubes (MWCNTs). Under UV irradiation, the diazonium group of diazo-tpy is decomposed and the residual terpyridine group is covalently anchored to the surface of substrates. The obtained tpy-modified MWCNTs (tpy-MWCNTs) have good solubility in common organic solvents. TGA and HRTEM analyses confirmed that terpyridine groups have been symmetrically grafted on MWCNTs. The thickness of the tpy-modified monolayer is about 2.3 nm, which is approximately 2 times the axial length of the 4-(2,2′:6′,2′′-terpyrid-4′-yl)phenyl group. The introduction of terpyridine groups on the surface of MWCNTs provides a coordination site to complex with metal ions. Multilayer films were fabricated from tpy-MWCNTs and ruthenium ions [Ru(III)] via the layer-by-layer self-assembled (LBL SA) technique on the tpy-modified quartz wafer, ITO glass, or silicon. The UV−vis results indicate that (1) Ru(III)-tpy-MWCNT SA multilayer films are successfully formed based on the coordination interaction between ruthenium ions and terpyridine groups, and (2) a progressive assembly occurred regularly with almost an equal amount of deposition in each cycle. The SEM image showed a highly covered Ru(III)-tpy-MWCNT film on the substrate. Moreover, the optoelectronic conversion was also studied by assembling Ru(III)-tpy-MWCNT multilayer films on ITO substrates. Under illumination, the LBL SA films on ITO showed an effective photoinduced charge transfer because of their conjugated structure and the ITO current density changed with the number of bilayers. As the number of bilayer increases, the photocurrent intensity increases and reaches its maximum (∼65 nA/cm2) at six bilayers. These results allow us to design novel materials for applications in optoelectronic devices by using LBL SA techniques.

Optically active polymers with main-chain helical chiralities have attracted long-standing interest for their wide potential applications in asymmetric synthesis, molecular recognition, and photoelectrical materials.

No abstract