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One-pot synthesis of palladium nanoparticles (PdNPs) has been achieved using calix[4]pyrrole hydrazide (MCPTH) as both reducing as well as capping agent. The synthetic procedure involves the use of environmentally benign water as solvent media. MCPTH-PdNPs have been characterized by using various analytical techniques. Transmission electron microscope analysis visualized the presence of well-dispersed and spherical Pd nanoparticles with an average dimension of 3–4 nm. Powder X-ray diffraction pattern portrayed the presence of face-centered cubic crystal structured PdNPs. A zeta potential value of − 26.2 mV suggests better stability of the nanoparticles. The heterogeneous catalytic activity of MCPTH-PdNPs was studied by probing the reduction of two carcinogenic azo dyes, namely, methylene blue and methyl orange in the presence of sodium borohydride. A remedial pathway for the process of dye degradation is proposed where the catalytic activity of Pd is faciled by the transfer of electrons from MCPTH to the metal centre. The mechanism for dye degradation is further substantiated by Density Functional Theory (DFT) calculations. The results of this work provide not only insight into fabrication of nanoparticles using calixarene platforms but also open new vistas to environmental remediation. [ABSTRACT FROM AUTHOR]

The impregnation of new azocalixpyrroles obtained from resorcinol derivative into a polymeric chelating resin, Amberlite XAD-2. A simple and effective method is presented for the separation and preconcentration of U(VI)] and Thorium Th(IV) by solid phase extraction on synthesized modified polymeric chelating resin. The synthesized chelating polymeric sorbent showed superior binding affinity towards U(VI) and Th(IV) under selective pH conditions. The optimum pH range was established and the flow rates for U(VI) and Th(IV) were studied respectively. U(VI) and Th(IV) are quantitatively eluted with suitable eluants like HCl and HNO3 and determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Other parameters such as total sorption capacity, exchange kinetics, preconcentration factor, distribution coefficient, breakthrough capacity and resin stability. The uptake and stripping of these metal ions on the resin were fast, indicating a better accessibility of the metal ions towards the chelating sites. Chromatographic separation of Th(IV) and U(VI) was accomplished by adjustment of pH in the range of 3.0-9.0 pH, respectively. Separation of Th(IV) and U(VI) from other metal cations, in synthetic solution was achieved. The synthesized resins were recycled at least 14-16 times without much affecting column sorption capacity. [ABSTRACT FROM AUTHOR]

Novel Supramolecular fluorescence receptor derived from calix-system i.e. calix[4]resorcinarene bearing dansylchloride as fluorophore was designed and synthesized. The compound was purified by column chromatography and characterized by elemental analysis, NMR and Mass spectroscopy. Tetradansylated calix[4] resorcinarene ( TDCR) shows a boat conformation with Cv symmetry. The complexation behaviour of metal cations [Ag(I), Cd(II), Co(II), Fe(III), Hg(II), Cu(II), Pb(II), Zn(II), U(VI) (1 × 10 M)] with tetra dansylated calix[4]resorcinarene (1 × 10 M) was studied by spectophotometry and spectrofluorometry. Red shift in the absorption spectra led us to conclude that there is strong complexation Fe(III), Co(II) and Cu(II) with TDCR. These metal cations also produce quenching with red shifts in the emission spectra. The maximum quenching in emission intensity was observed in the case of Fe(III) and its binding constant was also found to be significantly higher than that of Co(II) and Cu(II). Quantum yield of metal complexes of Fe(III) was found to be lower in comparison with Co(II) and Cu(II) complexes. Stern Volmer analysis indicates that the mechanism of fluorescence quenching is either purely dynamic, or purely static. [ABSTRACT FROM AUTHOR]