A novel series of pyrazole derivatives toward biological applications: experimental and conceptual DFT characterization.

A new series of 13 pyrazole-derivative compounds with potential antifungal activity were synthetized with good yields. The series have the (E)-2-((1-(R)-3,5-dimethyl-1H-pyrazol-4-yl)diazenyl)phenol general structure and were characterized by means of X-ray diffraction, UV-Vis, FTIR, 1H-NMR, 13C-NMR, and two-dimensional NMR experiments. This experimental characterization was complemented by DFT simulations. A deep insight regarding molecular reactivity was accomplished employing a conceptual DFT approach. In this sense, dual descriptors were calculated at HF and DFT level of theory and GGV spin-density Fukui functions. The main reactive region within the molecules was mapped through isosurface and condensed representations. Finally, chemical descriptors that have previously shown to be close related to biological activity were compared within the series. Thus, higher values of chemical potential ω and electrophilicity χ obtained for compounds 10, 9, 8, 6 and 7, in this order, suggest that these molecules are the better candidates as biological agents.

In-Situ Preparation of CdTe Quantum Dots Capped with a ß-Cyclodextrin-Epichlorohydrin Polymer: Polymer Influence on the Nanocrystal's Optical Properties.

ß-Cyclodextrin (ßCD), the less water soluble of the cyclodextrins, has been used as a capping agent in the preparation of semiconductor nanocrystals or quantum dots (QDs). Nevertheless, no reports have been found in the use of the highly water-soluble polymer of this, prepared by the crosslinking of the ßCD units with epichlorohydrin in basic medium (ßCDP). This polymer, besides to overcome the low solubility of the ßCD, increases the inclusion constant of the guest; two parameters that deserve its use as capping agent, instead of the native cyclodextrin. In the present manuscript, we afforded the in-situ aqueous preparation of cadmium telluride (CdTe) QDs capped with ßCDP. The polymer influence on the photoluminescent properties of the nanocrystals was analyzed. The ßCDP controls the nanocrystals growth during the Oswald ripening stage. Consequently, the CdTe capped ßCDP QDs showed lower Stokes-shift values, higher photoluminescent efficiency, and narrower size distribution than for nanocrystals obtained in the absence of polymer. Transmission electron microscopy (TEM) micrographs and energy dispersive X-ray spectroscopy (EDS) analysis revealed the composition and crystallinity of the CdTe QDs. This ßCDP capped CdTe QDs is a potential scaffold for the supramolecular modification of QDs surface.

Synthesis of Au Nanoparticles Assisted by Linker-Modified TiO2 Nanoparticles.

Plasmonic nanoparticles, especially gold ones, have been widely employed as photosensitizers in photoelectrovoltaic or photocatalytic systems. To improve the system's performance, a greater interaction of the nanoparticles with the semiconductor, generally TiO2, is desired. Moreover, this performance is enhanced when an efficient covering of TiO2 surface by the sensitizer is achieved. The Brust-Schiffrin-like methods are of the most employed approaches for nanoparticles synthesis. In a traditional approach, the reduction of the gold precursor is performed in the presence of a stabilizer (typically a thiol molecule) free in solution. A second step in which the obtained nanoparticles are anchored to the semiconductor surface is necessary in the case of photosensitive applications. Drawbacks like steric hindrance turn more difficult the covering of the semiconductor's surface by nanoparticles. In this paper, we report a variation of this methodology, where the linker is previously anchored to the TiO2 nanoparticles surface. The resulting system is employed as the stabilizer in the gold reduction step. This strategy is carried out in aqueous media in two simple steps. A great covering of the titania surface by gold nanoparticles is achieved in all cases and the gold nanoparticles in the resulting nanoaggregate might be useful for photoelectrovoltaic or photocatalytic applications.