In this paper, calcium molybdate (CaMoO4) crystals (meso- and nanoscale) were synthesized by the coprecipitation method using different solvent volume ratios (water/ethylene glycol). Subsequently, the obtained suspensions were processed in microwave-assisted hydrothermal/solvothermal systems at 140 °C for 1 h. These meso- and nanocrystals processed were characterized by X-ray diffraction (XRD), Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), ultraviolet−visible (UV−vis) absorption spectroscopies, field-emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) measurements. XRD patterns and FT-Raman spectra showed that these meso- and nanocrystals have a scheelite-type tetragonal structure without the presence of deleterious phases. FT-IR spectra exhibited a large absorption band situated at around 827 cm−1, which is associated with the Mo−O antisymmetric stretching vibrations into the [MoO4] clusters. FEG-SEM micrographs indicated that the ethylene glycol concentration in the aqueous solution plays an important role in the morphological evolution of CaMoO4 crystals. High-resolution TEM micrographs demonstrated that the mesocrystals consist of several aggregated nanoparticles with electron diffraction patterns of monocrystal. In addition, the differences observed in the selected area electron diffraction patterns of CaMoO4 crystals proved the coexistence of both nano- and mesostructures. First-principles quantum mechanical calculations based on the density functional theory at the B3LYP level were employed in order to understand the band structure and density of states for the CaMoO4. UV−vis absorption measurements evidenced a variation in optical band gap values (from 3.42 to 3.72 eV) for the distinct morphologies. The blue and green PL emissions observed in these crystals were ascribed to the intermediary energy levels arising from the distortions on the [MoO4] clusters due to intrinsic defects in the lattice of anisotropic/isotropic crystals.

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Urea has been covalently immobilized onto silica gel by reaction of urea with a silanized agent attached to silica or by reaction of the previously synthesized molecule containing both urea and silanizing agent with the support, giving 0.55 and 0.92 mmol of urea per gram of silica, respectively. The physical surface area and infrared, proton and solid-state carbon NMR spectra are similar for both surfaces, which extract MCI, (M = Ni, Co, Zn, Cu, Cd, Hg) from acidic water, ethanol and acetone solutions at 298 K. The retention of cations in aqueous solution increases the pH, with Ni and Hg being the most strongly adsorbed. The chemisorption isotherms obtained in non-aqueous media are similar and fit the Langmuir equation. The sequence of maximum retention capacity is Zn > Cu > Hg > Ni > Co and Cu > Co > Zn for ethanol and acetone, respectively. The integral heats of adsorption of cations by the immobilized surface at 298.2 K were larger in ethanol. With the exception of Co (A/-/= +25.51 k0.08 kJ mol-'), the cation interactions are exothermic in acetone. The value for Cd (AH= -35.91 k0.04 kJ mol-') contrasts with the results found in ethanol, which are endothermic and about one-third of the Cd value. Electronic spectra of the solid suspended in carbon tetrachloride, collected after batchwise adsorption, are in agreement with a tetrahedral geometry for Ni, Co and Cu.

A judicious combination of materials and molecular architectures has led to enhanced properties of layerby-layer (LbL) films, in which control at the molecular level can be achieved. In this paper we provide one such example by showing that supramolecular effects in electroactive LbL films comprising tetrasulfonated metallophthalocyanines (NiTsPc or FeTsPc) alternated with poly(allylamine hydrochloride) (PAH) may depend on both the choice of material and the film-forming technique. Indeed, though some properties such as film growth were common to both types of LbL film, those containing NiTsPc displayed unique features. PAH/ NiTsPc films assembled onto ITO (indium tin oxide) showed two redox processes, with E 1/2 at 0.54 and 0.80 V (vs SCE) attributed to the phthalocyanine unit ([TsPc] 6-/[TsPc] 5-) and Ni 2+ /Ni 3+ redox couple, respectively. In contrast, only one redox process was observed for PAH/FeTsPc films, with E 1/2 at 0.45 V assigned to the [TsPc] 6-/[TsPc] -5 couple. For both systems, the anodic peak current versus scan rate increased up to 500 mV‚s -1 , indicating that the electrochemical response of NiTsPc and FeTsPc in LbL films is governed by charge-transport mechanism. Interestingly, the second redox process for PAH/NiTsPc became totally reversible at high scan rates, showing fast charge transfer. The influence from the film-forming technique was proven by comparison with results from an electrodeposited film of NiTsPc on ITO, which was less stable than its LbL counterpart. It is envisaged that the high electrochemical stability, reversibility, and unique features arising from the supramolecular structure of PAH/NiTsPc LbL films may be exploited in applications such as electrochromic and sensing devices.