Project description:The development of new chromophoric receptors capable of binding curved carbon nanostructures is central to the quest for improved fullerene-based organic photovoltaics. We herein report the synthesis and characterization of a subphthalocyanine-based multicomponent ensemble consisting of two electron-rich SubPc-monomers rigidly attached to the convex surface of an electron-poor SubPc-dimer. Such a unique configuration, especially in terms of the two SubPc-monomers, together with the overall stiffness of the linker, endows the multicomponent system with a well-defined tweezer-like topology to efficiently embrace a fullerene in its inner cavity. The formation of a 1 : 1 complex was demonstrated in a variety of titration studies with either C60 or C70. In solution, the underlying association constants were of the order of 105 M-1. Detailed physicochemical experiments revealed a complex scenario of energy- and electron-transfer processes upon photoexcitation in the absence and presence of fullerenes. The close proximity of the fullerenes to the electron-rich SubPcs enables a charge shift from the initially formed reduced SubPc-dimer to either C60 to C70.
Project description:Previously, we have demonstrated that thermal-assisted techniques can accelerate the extraction of inert platinum group metals (PGMs), while they still have several concerns about difficulty of temperature control in actual extraction contactors and safety risks arising from heating organic solvents. In this study, we report a complexation-distribution separated extraction process for the accelerated extraction of inert PGMs. This extraction method includes two steps: (1) complexation of PGMs with extractants in aqueous solution and (2) distribution of the formed complex from the aqueous phase to organic one. We separately investigated the complexation and distribution processes for typical inert PGMs such as Ru(III) and Rh(III) in the presence of water-soluble N,N,N',N'-tetra-alkylpyridinediamide ligands (PDA) and bis(trifluoromethylsulfonyl)amide (Tf2N-) counteranions. As a result, the water-soluble complexes of Ru(III) and Rh(III) with PDA can be formed in 0.5 M HNO3(aq) within 3 h under heating at 356 K. The formed complexes were extracted to the 1-octanol layer containing Tf2N- within 5 min at room temperature, where this hydrophobic anion plays an important role to promote extraction of PGMs as an anionic phase-transfer catalyst (PTC). Consequently, we successfully established and demonstrated the complexation-distribution separated extraction process for the accelerated extraction of inert PGMs using a water-soluble ligand and anionic PTC.
Project description:Zearalenone (ZEN) is a nonsteroidal estrogenic mycotoxin produced by various Fusarium species and commonly occurring in corn and other cereals. Even though its acute toxicity is low, still the estrogenic activity of ZEN and metabolites is a matter of concern. In this work, a new magnetic molecularly imprinted polymer (mMIP) for the selective extraction of ZEN from cereal flours is presented. The mMIP was synthesized previously using quercetin as dummy template, and here we wanted to test its applicability to complex food samples. Analyte determination was carried out by high-performance liquid chromatography coupled to tandem mass spectrometry. The selectivity of the mMIP and the main validation method parameters were assessed. In particular, even in samples as complex as cereals, matrix effect was negligible. Although the mMIP showed cross-selectivity towards both ZEN-related and quercetin-related compounds, nonetheless ZEN recovery was > 95% for the two lower spiking levels, and the quantification limit was 0.14 ng g-1, i.e., ca. 500 times lower than the maximum limit fixed for most cereals by European law. Therefore, the material, also in comparison with a commercial sorbent, appears suitable for the application in food analysis, also to isolate ZEN at trace levels.
Project description:The efficient extraction recovery of scandium (Sc(iii)) is crucial for its application in high-end technology. Two novel hydrophobic carboxylic acid ionic liquids (ILs), namely, [lauryl betaine][bis(trifluoromethanesulphonyl)imide] ([Laur][Tf2N]) and [cocamidopropyl betaine][bis(trifluoromethanesulphonyl)imide] ([Coca][Tf2N]), were synthesized using two inexpensive amphoteric surfactants as cation sources. [Laur][Tf2N] (257 °C) and [Coca][Tf2N] (251 °C) exhibited good thermal stability and strong hydrophobicity. The viscosity of [Coca][Tf2N] (4.29 × 103 mP s) was higher than that of [Laur][Tf2N] (2.55 × 103 mPa s) at 25 °C. The optimal extraction conditions were an extraction equilibrium time of 40 min, an initial Sc(iii) concentration of 0.001 mol L-1, a sodium nitrate concentration of 0.5 mol L-1, and a pH of 3. The extraction efficiency of [Laur][Tf2N] and [Coca][Tf2N] could even exceed 98.7% and 96.0%, respectively. The cation exchange extraction mechanism was studied by slope analysis, IR spectroscopy and 13C NMR spectroscopy. Sc(iii) extracted using [Laur][Tf2N] and [Coca][Tf2N] could be completely stripped with 0.1 mol L-1 and 0.2 mol L-1 HNO3 once, respectively. The structure of the ILs was not broken after stripping, and the extraction efficiency of the ILs remained almost unchanged after five cycles. In addition, the extraction differences at different pH levels made it possible to separate Sc(iii) from other rare earths using ionic liquids [Laur][Tf2N] and [Coca][Tf2N].
Project description:In this work, the design of a monolithic softener obtained by geopolymer gel conversion is proposed. The softener used consists in a geopolymeric macroporous matrix functionalized by the co-crystallization of zeolite A and X in mixture. The dual nature of the proposed material promotes a softening process based on the synergistic effect of cation exchange and alkaline precipitation. A softening capacity of 90% and 54% for Ca2+ and Mg2+ respectively was attained in 24 h. In fact, the softener reported a Cation Exchange Capacity (CEC) value of 4.43 meq g-1. Technical features such as density, porosity and mechanical resistance were also measured. The use of this monolithic softener can improve performance and sustainability of hardness removal from tap water, reducing the production of sludge and adding the possibility to partially regenerate or reuse it.
Project description:Two carbazole sulfonamide-based macrocycles 1 and 2 were facilely synthesized and carefully evaluated for their anion recognition properties. The obtained results revealed that macrocycle 1 with a 1,3-xylyl linker was able to bind fluoride ion more strongly and selectively in acetonitrile medium than its strong competitors (like acetate and dihydrogen phosphate anions), with a large binding constant (K a) of 50 878 M-1. More importantly, an exclusive fluoride recognition was achieved for macrocycle 1 in the more polar DMSO-d 6 solution, albeit with a moderate affinity of K a = 147 M-1. Compared with macrocycle 1, macrocycle 2 bearing a 2,6-lutidinyl linkage exhibited a remarkable change not only in the anion affinity but also in the anion selectivity, although with only a slight difference in their molecular structures.
Project description:A H2SO4-H2O2 system was developed to enhance the efficacy of vanadium extraction from roasted vanadium steel slag. The optimum parameters and the behavior of vanadium extraction were investigated systematically. When 1 mL of H2O2 per gram of vanadium slag was added to a leaching mixture at 50 °C, along with 30% H2SO4, 80.5% of vanadium extraction was achieved within 15 min. However, without H2O2, only 58.5% of vanadium extraction was achieved at the same leaching time. The H2SO4-H2O2 system facilitated the dissolution of metallic ions in a short time and then triggered the production of strong oxidizing substances, such as HO• and O2 -•, via the Fenton reaction and Fenton-like reaction. Subsequently, the low-valence vanadium, existing in the leaching solution or located on the surface of the particle, was converted to pentavalent vanadium by strongly oxidizing substances, such as H2O2 and its derivatives HO• and O2. The complex oxides on the surface of the particle were destroyed, after which the vanadium inside the particle was gradually exposed to the acid leaching solution. The vanadium was oxidized to pentavalent vanadium, which then entered the leaching solution. Finally, a pathway of vanadium extraction via the H2SO4-H2O2 system was proposed to gain insight into rapid vanadium leaching.
Project description:The widespread implementation of H2 as a fuel is currently hindered by the high pressures or cryogenic temperatures required to achieve reasonable storage densities. In contrast, the realization of materials that strongly and reversibly adsorb hydrogen at ambient temperatures and moderate pressures could transform the transportation sector and expand adoption of fuel cells in other applications. To date, however, no adsorbent has been identified that exhibits a binding enthalpy within the optimal range of -15 to -25 kJ/mol for ambient-temperature hydrogen storage. Here, we report the hydrogen adsorption properties of the metal-organic framework (MOF) V2Cl2.8(btdd) (H2btdd, bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin), which features exposed vanadium(II) sites capable of backbonding with weak π acids. Significantly, gas adsorption data reveal that this material binds H2 with an enthalpy of -21 kJ/mol. This binding energy enables usable hydrogen capacities that exceed that of compressed storage under the same operating conditions. The Kubas-type vanadium(II)-dihydrogen complexation is characterized by a combination of techniques. From powder neutron diffraction data, a V-D2(centroid) distance of 1.966(8) Å is obtained, the shortest yet reported for a MOF. Using in situ infrared spectroscopy, the H-H stretch was identified, and it displays a red shift of 242 cm-1. Electronic structure calculations show that a main contribution to bonding stems from the interaction between the vanadium dπ and H2 σ* orbital. Ultimately, the pursuit of MOFs containing high densities of weakly π-basic metal sites may enable storage capacities under ambient conditions that far surpass those accessible with compressed gas storage.
Project description:The pancreatic cancer is the fourth leading cause of cancer-related death and characterized by one of the lowest five-year survival rate. The current therapeutic options are demonstrating minimal effectiveness, therefore studies on new potential anticancer compounds, with non-significant side effects are highly desirable. Recently, it was demonstrated that vanadium compounds, in particular organic derivatives, exhibit anticancer properties against different type of tumor as well as favorable biodistribution from a pancreatic cancer treatment perspective. In this research, we showed selective cytotoxic effect of vanadium complexes, containing phenanthroline and quinoline as an organic ligands, against human pancreatic ductal adenocarcinoma cell line (PANC-1), compared to non-tumor human immortalized pancreas duct epithelial cells (hTERT-HPNE). Results exhibited that vanadium complexes inhibited autophagy process in selective cytotoxic concentration as well as caused the cell cycle arrest in G2/M phase associated with mitotic catastrophe and increased level of reactive oxygen species (ROS). Moreover, in higher concentration, vanadium derivatives induced a mix type of cell death in PANC-1 cells, including apoptotic and necroptotic process. Our investigation emphasizes the anticancer potential of vanadium complexes by indicating their selective cytotoxic activity, through different process posed by alternative type of cell deaths to apoptosis-resistant cancer cells. Further studies supporting the therapeutic potential of vanadium in pancreatic cancer treatment is highly recommended.
Project description:A new series of lanthanide (1-5) and uranyl (6) complexes with a tetra-substituted bifunctional calixarene ligand H2 L is described. The coordination environment for the Ln3+ and UO2 2+ ions is provided by phosphoryl and salicylamide functional groups appended to the lower rim of the p-tert-butylcalix[4]arene scaffold. Ligand interactions with lanthanide cations (light: La3+ , Pr3+ ; intermediate: Eu3+ and Gd3+ ; and heavy: Yb3+ ), as well as the uranyl cation (UO2 2+ ) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2 : 2 M : L, [Ln2 (L)2 (H2 O)]2+ (1-5), in solution, whereas uranyl formed a 1 : 1 M : L complex [UO2 (L)(MeOH)]∞ (6) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H2 L was found to be an effective extracting agent for UO2 2+ over La3+ and Yb3+ cations. The separation factors at pH 6.0 are: βUO 22+ /La 3+ =121.0 and βUO 22+ /Yb 3+ =70.0.