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The thermodynamics of binding between native α- and β-cyclodextrin towards several p-nitro-aniline derivatives was examined, in order to gain further insights about the occurrence of different interaction modes for the two hosts. Valuable information was achieved regarding the ‘expanded hydrophobic sphere’ of α-cyclodextrin. Furthermore, very interesting and unexpected aspects of the behavior of β-cyclodextrin were enlightened, such as the crucial role played by hydrogen bond interactions. Experimental data were examined under the perspective of the ‘enthalpy–entropy compensation effect’, and some ideas about this topic are discussed. [Copyright &y& Elsevier]

The stability and stoichiometric ratio of binary complexes among five fluorophores and β-cyclodextrin (β-CD) or heptakis-(6-amino-6-deoxy)-β-cyclodextrin (am-β-CD) were determined by means of fluorescence measurements in borate buffer at pH=8.0 and 9.0. Structure of both host and guest affected the characteristics of the binary complexes. Pyrene and anthraquinone formed a 1:2 (fluorophore: cyclodextrin) complex with both cyclodextrins. Xanthone formed 1:1 complex with β-CD and 1:2 complex with am-β-CD. A more defined behaviour was observed for crysene. In fact, both stoichiometric different complexes were detected with both hosts. Only 1:1 complexes were observed for antracene. The complex stability was affected by the pH of the solution. MM2 calculations were performed in order to gain information about the forces working on the formation of complexes. [Copyright &y& Elsevier]

Nowadays, water pollution represents a serious problem both for agriculture and human health. Find innovative strategy for a large-scale removal of pollutants from wastewaters is thus a challenge. In this context, both cyclodextrin derivatives and clay minerals have been used as low-cost nanomaterials for the sorption of pollutants because of their features. Cyclodextrin derivatives are particularly recognized for the removal of organic chemicals, drugs, and pesticides from wastewater. Hectorite (Ht), a clay mineral of smectite group, shows high cation exchange capacity and negatively charged basal surfaces that could allow the removal both of heavy metal ions and organic pollutants. Herein, the synthesis of a hybrid organic/inorganic nanomaterial based on the chemical modification of Ht by grafting modified β-cyclodextrin units is reported. In this way systems with complementary and synergistic adsorption ability for removal of both organic pollutants and heavy metal ions were developed. Two different synthetic approaches were investigated, and the obtained nanomaterials were subjected to thorough structural characterization by FT-IR and 13C solid state NMR spectroscopies, dynamic light scattering, and ζ-potential measurements and the loading of organic moieties was verified by thermogravimetric analysis. In addition, the morphology was investigated by high angle annular dark field transmission electron microscopy (HAADF/STEM) coupled with energy dispersive X-ray spectroscopy (EDX). The synthetized nanomaterial was tested as a sorbent for the removal of antibiotics, organic dyes and heavy metal ions. Finally, the simultaneous filtration of ciprofloxacin and Pb(II) ions, chosen as models, from simulated wastewater by a column filtration laboratory prototype was investigated, too. [Display omitted] • The synthesis of organic/inorganic nanomaterial based on hectorite and β-cyclodextrin is reported. • The nanomaterial was tested as a sorbent for the removal of different pollutant • Thanks to cyclodextrins the nanomaterial showed better adsorption performance than hectorite • Recycling tests showed that the nanomaterial can be reused for at least 4 cycles. • A laboratory column filtration system was set up to simultaneously remove different pollutants [ABSTRACT FROM AUTHOR]

Silver nanoparticles stabilized by means of poly -(6- N , N -dimethyl-propylenediamino)-(6-deoxy)-β-cyclodextrin were synthesized, characterized by different techniques (UV–vis spectroscopy, Dynamic Light Scattering, High Resolution Transmission Electron Microscopy, Fourier-transform IR Spectroscopy) and used as catalysts for the reduction of various nitrobenzene derivatives with sodium borohydride. The nanocomposites obtained appear to have an organized structure, with a metal core surrounded by a layer-structured coating shell. Kinetic data, rationalized in terms of a modified Langmuir–Hinshelwood model, evidenced a non-linear dependence of the reaction rate on the concentration of the catalyst. This was explained on the grounds of the catalytic activity of differently covered catalyst areas. Careful analysis of kinetic data, in particular the effect of the para substituent on the nitroarene structure and the trends of the induction period observed at the beginning of the reaction, provided with interesting insights on the reaction course, and brought us to critically reconsider several mechanistic ideas reported in previous literature. [ABSTRACT FROM AUTHOR]