In this paper, we demonstrate that chiral J-aggregates of porphyrins are able to detect minute chiral impurities, in this case, the presence of right-handed quartz in acid-activated K10 montmorillonite clay. Aggregation and symmetry breaking of 5,10,15,20-(tetra-4-carboxyphenyl) porphyrin (TCPP) and 5,10,15,20-(tetra-4-sulfonatophenyl) porphyrin (TPPS) were observed upon interaction with acid-activated montmorillonite clay (MMT-K10). A panel of characterization techniques, including UV-visible, electronic circular dichroism, IR, and vibrational circular dichroism spectroscopies, as well as X-ray scattering, were employed to investigate the aggregation of the confined TPPS and TCPP.
View Article and Find Full Text PDFA current challenge in silicon chemistry is to perform liquid-phase synthesis of silicon nanoparticles, which would permit the use of colloidal synthesis techniques to control size and shape. Herein we show how silicon nanoparticles were synthesized at ambient temperature and pressure in organic solvents through a redox reaction. Specifically, a hexacoordinated silicon complex, bis(,'-diisopropylbutylamidinato)dichlorosilane, was reduced by a silicon Zintl phase, sodium silicide (NaSi).
View Article and Find Full Text PDFBecause the combination of chiral and magnetic properties is becoming more and more attractive for magneto-chiral phenomena, we here aim at exploring the induction of chirality to achiral magnetic molecules as a strategy for the preparation of magneto-chiral objects. To this end, we have associated free base- and metallo-porphyrins with silica nano helices, using a variety of elaboration methods, and have studied them mainly by electronic natural circular dichroism (NCD) and magnetic circular dichroism (MCD) spectroscopies. While electrostatic or covalent surface grafting uniformly yielded very low induced CD (ICD) for the four assayed porphyrins, a moderate response was observed when the porphyrins were incorporated into the interior of the double-walled helices, likely due to the association of the molecules with the chirally-organized gemini surfactant.
View Article and Find Full Text PDFAlkylation of aromatic hydrocarbons is among the most industrially important reactions, employing acid catalysts such as AlCl, HSO, HF, or HPO. However, these catalysts present severe drawbacks, such as low selectivity and high corrosiveness. Taking advantage of the intrinsic high acid strength and Lewis and Brønsted acidity of niobium oxide, we have designed the first series of NbO-SiO(HIPE) monolithic catalysts bearing multiscale porosity through the integration of a sol-gel process and the physical chemistry of complex fluids.
View Article and Find Full Text PDFThe linear trinuclear complex cation [Fe(DpyF)] was prepared as [Fe(DpyF)](BF)·2CHCN. With large Fe-Fe distances of 2.78 Å, this complex demonstrates intramolecular ferromagnetic coupling between the anisotropic Fe centers (/ = +20.
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