High sulfur content copolymers were prepared via inverse vulcanization of sulfur with 1,4-diphenylbutadiyne (DiPhDY) for use as the active cathode material in lithium-sulfur batteries. These sulfur-rich polymers exhibited excellent capacity retention (800 mA h g À1 at 300 cycles) and extended battery lifetimes of over 850 cycles at C/5 rate. Fig. 3 (a) Cycling performance at C/5 of Li-S battery fabricated with poly(S-co-DiPhDY) prepared with a 10 wt% DiPhDY, 90 wt% sulfur feed ratio. (b) Plot of potential versus charge/discharge capacity for the Li-S cell shown in (a) at 100 cycle intervals. (c) Charge/discharge rate performance of Li-S battery with poly(S-co-DiPhDY) (10 wt% DiPhDY) at various current densities (1 C ¼ 1672 mA h). All capacities are specific capacity based on sulfur loading.This journal is

The synthesis of a new oligophenyleneethynylene (OPE)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) bolaamphiphile 1 and its aqueous self-assembly are reported. Compound 1 forms H-type aggregates in aqueous and polar media, as demonstrated by UV/Vis and fluorescence experiments. Concentration-dependent (1)H NMR studies in CD3CN reveal that the BODIPY units are arranged on top of each other into π-stacks with H-type excitonic coupling, as supported by ROESY NMR and theoretical calculations and visualized by Cryo-SEM studies. A detailed analysis of the spectral changes observed in temperature-dependent UV/Vis studies reveals that 1 self-assembles in a non-cooperative (isodesmic) fashion in water. The hydrophobic interior of these self-assembled structures can be exploited to encapsulate hydrophobic dyes, such as tetracene and anthracene. Both dyes absorb in a complementary region of the UV/Vis spectrum and are small enough to interact with the hydrophobic segments of 1. Temperature-dependent UV/Vis studies reveal that the spectral changes associated to the encapsulation mechanism of tetracene can be fitted to a Boltzmann function, and the initially flexible fibres of 1 rigidify upon guest addition. In contrast, the co-assembly of 1 and anthracene is a highly cooperative process, which suggests that a different class of (more-ordered) aggregates is formed. TEM and Cryo SEM imaging show the formation of uniform spherical nanoparticles, indicating that a subtle change in the guest molecular structure induces a significant change in the encapsulation mechanism and, consequently, the aggregate morphology.

Supramolecular chemistry: The self-assembly of an oligo(p-phenyleneethynylene)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (OPE-BODIPY) system into alternated 1D π stacks in solution exhibited liquid-crystalline properties at room temperature. This system represents a new approach towards a controlled dye organization exclusively driven by π-π interactions (see figure).