Self-assembled microtubes of mixed charge-transfer (CT) complexes comprising TCNB and naphthalene can be constructed with pyrene as dopant by an etching-assisted CT-induced interaction. Highly efficient Förster resonance energy transfer (FRET) from the excited naphthalene-TCNB to pyrene-TCNB molecules is obtained in mixed CT complex microtubes. White-light emissive CT complex microtubes can be formed by adjusting the dopant concentration and serve as an active optical waveguide.

Two-dimensional single-crystalline nanostructures of perylene with uniform square and rhombus shapes have been prepared successfully via a simple reprecipitation method with the assistance of surfactant CTAB templates. The X-ray diffraction (XRD) measurements reveal that the square and rhombus nanosheets can be indexed to α- and β-phase perylene crystals, respectively. On the basis of the analysis of time-dependent growth processes, we found that selective adhesion of CTAB molecules on the crystal (001) plane facilitates to the formation of sheetlike structures, whereas polymorph transition from α- to β-phase achieved by altering the surfactant CTAB concentration results in the evolution of the nanosheet from square to rhombus morphologies. Single-nanoparticle spectrscopy depicts that square and rhombus nanosheets show distinct shape-dependent optical properties that are directly related to their crystal structures. Furthermore, the optical waveguiding behaviors have been revealed through the scanning near-field optical microscopy (SNOM) technique. This expands the optical waveguides from 1D to 2D nanostructures and has a potential application in novel optoelectronic devices.

1D triblock hetrostructures with striping patterns have been synthesized by doping 1,3-diphenyl-2-pyroline (DP) microrods with 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) molecules selectively at both ends. The middle stripe of triblock microds emit the blue light, while both ends emit orange light due to the efficient FET from excited DP to DCM molecules (right inset). Although triblock microrods show microarea heterogeneity in the striping pattern, they generate macroscopic high-quality white-light emission (WLE) in both the colloidal suspension (left inset) and the solid state with a photoluminescence efficiency as high as 36 +/- 5%.

We report here a new ternary solvated (perylene-TCNB)·2THF cocrystal, which can transform into binary perylene-TCNB cocrystal reversibly by successive desorption or absorption of THF solvent. As a consequence, macroscopic mechanical bending would be realized when repeated stimulation with THF solvent. The present results clearly demonstrated that solvent induced mechanical bending is driven by structural change at the molecular scale. Such solvatomechanical bending behavior is clearly revealed for the first time.

A series of crystalline mixed cocrystal microtubes comprising organic charge-transfer (CT) complexes has been prepared. The emission colors of the mixed cocrystal microtubes can be tailored from green to orange at low dopant concentrations (0 < x ⩽ 5%), while their hexagonal cross sections can transform into square ones gradually at higher concentrations (0.15 < x < 1). In addition, we can further extend the solvent-processed synthetic route to other CT pairs based on structural compatibility consideration.

This article analyzes part of a ground water flow system in the North China Plain (NCP) subject to severe overexploitation and rapid depletion. A transient ground water flow model was constructed and calibrated to quantify the changes in the flow system since the predevelopment 1950s. The flow model was then used in conjunction with an optimization code to determine optimal pumping schemes that improve ground water management practices. Finally, two management scenarios, namely, urbanization and the South-to-North Water Transfer Project, were evaluated for their potential impacts on the ground water resources in the study area. Although this study focuses on the NCP, it illustrates a general modeling framework for analyzing the sustainability, or the lack thereof, of ground water flow systems driven by similar hydrogeologic and economic conditions. The numerical simulation is capable of quantifying the various components of the overall flow budget and evaluating the impacts of different management scenarios. The optimization modeling allows the determination of the maximum "sustainable pumping" that satisfies a series of prescribed constraints. It can also be used to minimize the economic costs associated with ground water development and management. Furthermore, since the NCP is one of the most water scarce and economically active regions in the world, the conclusions and insights from this study are of general interest and international significance.

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