Ultra-Bright Fluorescent Organic Nanoparticles Based on Small-Molecule Ionic Isolation Lattices

Ultra-bright fluorescent nanoparticles hold great promise for demanding bioimaging applications. Recently, extremely bright molecular crystals of cationic fluorophores were obtained by hierarchical co-assembly with cyanostar anion-receptor complexes of associated counterions. These small-molecule ionic isolation lattices (SMILES) ensure spatial and electronic isolation to prohibit dye aggregation quenching. We report a simple, one-step supramolecular approach to formulate SMILES materials into nanoparticles. Rhodamine-based SMILES nanoparticles stabilized by glycol amphiphiles show high fluorescence quantum yield (30%) and brightness per volume (5000 M–1 cm–1 / nm3) with 400 dyes packed into 16-nm particles, corresponding to an absorption coefficient of 4 × 107 M–1 cm–1. UV excitation of the cyanostar component leads to highest brightness (>6000 M–1 cm–1 / nm3) by energy transfer to rhodamine emitters. Coated nanoparticles stain cells and are thus promising for bioimaging

Mono and bimetallic NaY catalysts with high performance in nitrate reduction in water

The catalytic reduction of nitrate in water was performed with mono and bimetallic catalysts based on NaY zeolite. Four catalysts, two monometallic (Cu-Y and Pd-Y) and two bimetallic (CuPd-Y and PdCu-Y) were prepared by the ion-exchange method using the faujasite zeolite in the sodium form (NaY, 700. nm). The contents of promoter and noble metals were kept in the range of 0.60-0.84. wt% for copper and 0.92-1.80. wt% for palladium. Characterization by several methods: spectroscopic techniques (FTIR, XRD), chemical analysis, nitrogen adsorption, scanning electron microscopy (SEM), temperature programmed reduction (TPR) and cyclic voltammetric, demonstrated that ion exchange of the metals into NaY zeolite was successful. The catalytic behavior of the catalysts was evaluated in a semi-batch reactor, working at room temperature and pressure. The best catalyst was obtained with the pair copper and palladium (0.64. wt% of Cu and 1.80. wt% of Pd), which allowed 100% nitrate conversion with selectivities to nitrogen as high as 94% under the conditions tested.O.S.G.P. Scares acknowledge FCT for grant SFRH/BPD/97689/2013. The authors thank the FCT and FEDER-COMPETE-QREN-EU for financial support to the Research Centers, CQ/UM, PEst-C/QUI/UI0686/2013 (F-COMP-01-0124-FEDER-037302) and LCM group, UID/EQU/50020/2013. The authors also acknowledge sponsoring in the framework of the following research programs: NORTE-07-0124-FEDER-000039 and NORTE-07-0162-FEDER-000050, financed by QREN, ON-2 and FEDER.info:eu-repo/semantics/publishedVersio

Structural engineering of luminogens with high emission efficiency both in solution and in the solid state

Developing molecules with high emission efficiency both in solution and the solid state is still a great challenge, since most organic luminogens are either aggregation-caused quenching or aggregation-induced emission molecules. This dilemma was overcome by integrating planar and distorted structures with long alkyl side chains to achieve DApAD type emitters. A linear diphenyl–diacetylene core and the charge transfer effect ensure considerable planarity of these molecules in the excited state, allowing strong emission in dilute solution (quantum yield up to 98.2%). On the other hand, intermolecular interactions of two distorted cyanostilbene units restrict molecular vibration and rotation, and long alkyl chains reduce the quenching effect of the p–p stacking to the excimer, eventually leading to strong emission in the solid state (quantum yield up to 60.7%).NRF (Natl Research Foundation, S’pore)ASTAR (Agency for Sci., Tech. and Research, S’pore)Accepted versio