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Porphyrins are an important class of ligands with a tremendous ability to capture metal ions closely related to the rich coordination chemistry of porphyrins. Herein we use this characteristic to develop silica gel grafted derivatives for water remediation applications. Therefore, two porphyrin derivatives, one with three and the other with four mercaptopyridyl units were grafted on silica gel functionalized with 3-aminopropyltriethoxysilane. The new adsorbents Si3PyS and Si4PyS were characterized using a suitable set of techniques confirming the covalent attachment of the porphyrins to the silica surface. Additionally, microscopy and N2 adsorption analysis confirmed the structural integrity and preservation of the mesoporous structure of Si during surface modification. The results show that both hybrid materials exhibit good chemical and thermal stability and an outstanding Cu2+ removal capability, with a chemical adsorption capacity of 176.32 mg g–1 and 184.16 mg g–1, respectively. These materials have also been used in real water and industrial wastewater samples with minimal interference in their adsorption capabilities. Density Functional Theory calculations were performed to confirm the good performance of the hybrid materials Si3PyS and Si4PyS towards metal ions. The functionalization of silica surface with porphyrin-based ligands bearing additional binding motifs drastically improves the adsorption capability of the new hybrids towards metal ions. The presence of pyridyl units brings a meaningful advantage, since both porphyrin core and appended pyridyl groups are able of binding Cu2+ ions with high affinity, contributing to the enhancement of the chelating features of the adsorbents prepared when compared with other ligands supported in silica-based materials. published

A new sustainable and environmentally friendly adsorbent based on a β-ketoenol-pyrazole-thiophene receptor grafted onto a silica surface was developed and applied to the removal of heavy metal ions (Pb(II), Cu(II), Zn(II) and Cd(II)) from aquatic medium. The new material SiNPz-Th was well characterized and confirms the success of the covalent binding of the receptor on the silica surface. The effect of environmental parameters on adsorption including pH, contact time, temperature and the initial concentration were investigated. The maximum adsorption capacities of SiNPz-Th for Pb(II), Cu(II), Zn(II) and Cd(II) ions were 102.20, 76.42, 68.95 and 32.68 mg/g, respectively, at 30 min and pH = 6. The adsorption isotherms, kinetics and thermodynamic process were investigated and showed efficiency and selectivity towards Pb(II) and good regeneration performance. Density functional theory (DFT), non-covalent-interaction (NCI) and quantum theory of atoms in molecules (QTAIM) calculations were used to study and to gain a deeper understanding of both adsorption mechanism and selectivity of metal ions onto adsorbent. Accordingly, the metal ions such as Pb(II), Cu(II) and Zn(II) are bidentate coordinated with the adsorbent by nitrogen and oxygen atoms of Schiff base C=N and hydroxyl group –OH, respectively, to form stable complexes. While the Cd(II) is coordinated in a monodentate fashion with oxygen atom of hydroxyl group. Furthermore, the affinity of SiNPz-Th towards the metal ions was decreased in the order of Pb(II) ˃ Cu(II) ˃ Zn(II) ˃ Cd(II), in good agreement with experimental results. All these results highlight that the SiNPz-Th has a good potential to be an advanced adsorbent for the removal of lead ions from real water.

In the present study, we report the design and synthesis of new derivatives of the β-keto-enol grafted on pyridine and furan moieties (L 1 -L 11 ). Structures of compounds were fully confirmed by Fourier transform infrared spectroscopy (FT-IR), 1H NMR, 13C NMR, electrospray ionization/liquid chromatography-mass spectrometry (ESI/LC-MS), and elemental analysis. The compounds were screened for antifungal and antibacterial activities (Escherichia coli, Bacillus subtilis, and Micrococcus luteus). In vitro evaluation showed significant fungicidal activity for L 1 , L 4 , and L 5 against fungal strains (Fusarium oxysporum f.sp albedinis) compared to the reference standard. Especially, the exceptional activity has been demonstrated for L 1 with IC50 = 12.83 μg/mL. This compound and the reference benomyl molecule also showed a correlation between experimental antifungal activity and theoretical predictions by Petra/Osiris/Molinspiration (POM) calculations and molecular coupling against the Fgb1 protein. The highest inhibition of bacterial growth for L 1 is due to its strongest binding to the target protein. This report may stimulate the further synthesis of examples of this substance class for the development of new drugs.

Four novel heteroleptic mononuclear Fe(II) coordination complexes including 3,5-dimethyl-1-(2′-pyridyl)-pyrazole (DMPP) and aromatic sulfonate ligands were synthesized and characterized using single crystal-XRD, SQUID magnetometry and 57Fe Mossbauer spectroscopy. The crystal structures of the complexes revealed the unusual coordination of sulfonate groups to Fe(II) ions, leading to an Fe–N4O2 coordination environment. This specific molecular layout is presumably caused by diethyl ether, which was vapour diffused into the complexation medium to obtain crystalline complexes. Alongside yielding single crystals, diethyl ether also altered the self-assembly process of a usual FeN6 homoleptic coordination environment. All the complexes remain paramagnetic at all temperatures as suggested by magnetic susceptibility measurements. All are stable in air except [Fe(DMPP)2(tos)2] which got partially oxidized to Fe(III) over time as suggested by 57Fe Mossbauer spectroscopy.

The reaction of 1,5,5′-trimethyl-1H,1′H-3,3′-bipyrazole (Hbpz) with copper and manganese salts (Cu(BF4)2·6H2O, MnCl2·4H2O and Mn(NCS)2) leads to the formation of three mononuclear coordination complexes [Cu(Hbpz)3](BF4)2 (1), [Mn(Hbpz)2Cl2]·CH3CN (2) and [Mn(Hbpz)2(NCS)2]·Et2O (3). These compounds have been characterized using single crystal X-ray diffraction and infrared spectroscopy. The single crystal structures of 1, 2 and 3 are discussed in the context of the effect of hydrogen bonding functionalities and counter anions on the supramolecular structural diversities observed in these new coordination complexes.

Efficient hybrid materials based adsorbents are highly recommended for potentially toxic metals removal from polluted water media. Herein, novel silica particles modified with a new bispyrazolylpropane Schiff base were synthesized and characterized using relevant physical techniques. The resulting hybrid material (SiNAL3) was studied for its ability to uptake ZnII, CuII, PbII and CdII ions in aqueous solution via kinetics studies. The maximum adsorption capacities of SiNAL3 for ZnII, CuII, PbII and CdII were approximately 1.23, 0.32, 0.29 and 0.23 mmol g−1, respectively, with an equilibrium reached after only 25 min for all metals. The adsorption process was found spontaneous and endothermic. Interestingly, our hybrid material could selectively adsorb ZnII in the presence of other metal ions from an aqueous solution, a useful property which was applied to real water samples. The adsorbent can be easily reused with no significant decrease in adsorption capacity after not less than five adsorption-desorption cycles, demonstrating its high stability.

International audience; In this paper, the effect of Keto-enol derivatives namely (Z)-3-hydroxy-1-(pyridin-2-yl)but-2-en-1-one (KE-1) and (Z)-1-(1,5-dimethyl-1H-pyrazol-3-yl)-3-hydroxy-3-(pyridin-2-yl)prop-2-en-1-one (KE-2)on the inhibition of carbon steel (CS) corrosion in 1 M HCl has been studied using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical study. Weight loss measurements indicate that these compounds reduce the corrosion rate of carbon steel in acidic solution and the inhibition effect increases with the inhibitors concentration but decreases with temperature. The electrochemical polarization study revealed that the tested Keto-enol derivatives are mixed type. EIS show that the KE-1 and KE-2 form an adsorptive layer on the metallic surface. The adsorption of the KEs on the carbon steel surface obeys the Langmuir adsorption isotherm. The results of quantum chemical calculations and Monte Carlo simulation studies are in good agreement with experimental results.

Three new complexes namely [Cu(L1)H2O]·2H2O (1), [Cu2(L4)2(DMF)2(H2O)2](NO3)2 (4) and [{Cd2(L4)2Cl2(DMF)2}] (5), and two coordination polymers namely [Co(μ-L2)(DMF)2]·2H2O (2) and [Co(μ-L3)(DMF)2]·H2O (3) have been synthesized from a series of pyrazole-carboxylate ligands namely 1,1′-(ethane-1,2-diyl)bis(5-methyl-1H-pyrazole-3-carboxylic acid) (H2L1), 1,1′-(oxybis(ethane-2,1-diyl))bis(5-methyl-1H-pyrazole-3-carboxylic acid) (H2L2), 1,1′-(butane-1,4-diyl)bis(5-methyl-1H-pyrazole-3-carboxylic acid) (H2L3), and 2-(1′,5,5′-trimethyl-1H,1′H-[3,3′-bipyrazol]-1-yl)acetic acid (H2L4), and CuII/CdII/CoII ions. Single crystal structures of these compounds are discussed in the context of the effect of conformation of the ligands and supramolecular interactions observed within these edifices. Temperature-dependent magnetic data of 4 could be fitted best using two non-interacting CuII ions (S = 1/2) per molecule with giso = 2.28 and a temperature-independent paramagnetism, TIP = 1.75 × 10−5 cm3 mol−1.

The extraction and separation of heavy metals with several hybrid sorbents has been recognized as a promising green methodology. We present a novel and efficient host based on a modified silica gel with a bis(pyrazole)butane derivative as a chelating ligand; it was synthesized and studied for its adsorption capacity towards toxic heavy metals in aqueous media. The success of the synthesis of SiNAL4 was concluded from elemental analysis, Fourier transform-infrared spectroscopy, solid state 13C NMR, nitrogen adsorption–desorption isotherm, BET surface area, BJH pore size, scanning electron microscopy and thermogravimetry analysis. The effectiveness, regenerability and stability of the studied adsorbent were demonstrated. The optimum conditions for the removal of selected toxic metal ions were found to be pH = 6 and 25 min of contact time with the hybrid material. The maximum levels of ZnII, PbII, CdII and CuII uptake by the hybrid material were 86.51, 35.26, 26.96 and 20.24 mg g−1, respectively. The equilibrium isotherm models of the adsorbent were better described by a Langmuir model. The kinetics of heavy metal adsorption of the hybrid material followed a pseudo-second-order model and the thermodynamic parameters confirmed the spontaneous adsorption, and the spontaneity increases with the increase in temperature. The architecture of the hybrid material, when adsorbing the metal on the surface of the inorganic silica, was revealed using single crystal X-ray diffraction of a model material capturing CuII ions thanks to ligand coordination. Finally, the hybrid material was used in the treatment of river waters containing ZnII and CdII. The quantitative removal of the toxic metals under study from real aqueous solutions confirms the effectiveness of this new adsorbent compared to several previously described materials.

Water pollution by toxic elements represents a significant risk to the environment and human ecosystem, and a number of efforts are developed to find a suitable solution. In this work, a new adsorbent based on silica gel as an inert material modified on surface by a pincer ligand was prepared. The hybrid material has been synthesized via a simple Schiff base reaction and characterized by several relevant physical methods. The adsorbent shows an extremely rapid efficiency in removal of copper (less than 8 min) with maximum sorption capacity of 1.90 mmol g−1 and a rapid efficiency for zinc, cadmium and lead (less than 20 min) with adsorption capacities 0.52, 0.49 and 0.43 mmol g−1, respectively. A kinetic study shows that the sorption can be described by a pseudo second-order model, and that the process is thermodynamically spontaneous and endothermic. The adsorbent shows a high selectivity to Cu(II) and a great reusability after five adsorption-desorption cycles. Theoretical, energy dispersive X-ray fluorescence (EDX) and Fourier transform-infrared spectroscopy studies demonstrate that the uptake occurs by a coordination reaction between metal ions and the pincer ligand on the surface of the adsorbent. The efficiency of this new hybrid material was confirmed in removal of Cu(II) from real water samples originating from Abidjan Atlantic sea bay, one of the most polluted region in West Africa, as well as from rivers located near Oujda, Morocco.

During the last years, contamination of water by heavy metals has become a serious health hazard and environmental problem. In particular, mercury, lead, cadmium and zinc are considered as the most dangerous elements and are included on the US Environmental Protection Agency's (EPA) list of priority pollutants. To this end, the search for an effective material based adsorbent is a well-established technology. In this work, a novel and efficient host for the above toxic metals was synthesized by covalent immobilization of a new (E)-3-((2-nitrobenzylidene)amino) propan-1-ol Schiff's base receptor onto silica in a heterogeneous way to yield the material Si-CSB. The functionalized porous surface has been analyzed through elemental analysis, FT-IR spectroscopy, solid state 13C NMR, nitrogen adsorption–desorption isotherms, BET surface area, Barrett–Joyner–Halenda (BJH) pore diameters methods and thermogravimetric analysis (TGA). The new material showed great thermal and chemical stabilities examined in various acidic and buffer solutions. The adsorbent was applied in solid-phase extraction (SPE) and showed quantitative retention of Hg2 +, Pb2 +, Cd2 + and Zn2 + compared to previous described materials. The adsorption capability towards toxic metals was studied using kinetics, pH and temperature effects prior to their determination by ICP-AES. Adsorption was rapid as evidenced by equilibrium achieved within 25 min. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) revealed that the adsorption was spontaneous and endothermic. Alkali coexisting ions did not interfere with separation and determination. The material can be used continuously without reducing its extraction percentage. The newly synthesized material appears to be a low cost, effective and alternative adsorbent for efficient removal of heavy metals from aqueous solution.

A simple heterogeneous synthesis of pure adsorbent based polymer hybrid made by condensing a functionalized C,N-bipyrazole with a 3-glycidoxypropyl-trimethoxysilane silylant agent, previously anchored on a silica surface was developed. The formed material (SG2P) was characterized through elemental analysis, FT-IR spectroscopy, (13)C NMR of solid state, scanning electron microscope (SEM), and was studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and B.J.H. pore sizes. The new material exhibits good thermal stability determined by thermogravimetry curves and good chemical stability was examined in various acidic and buffer solutions (pH 1-7). The binding and adsorption abilities of SG2P were investigated for Hg(2+), Cd(2+), Pb(2+), Zn(2+), K(+), Na(+) and Li(+) cations and compared to the results of classical liquid-liquid extraction with the unbound C,N-bipyrazole compound. The grafting at the surface of silica does not affect complexing properties of the ligand and the SG2P exhibits a high selectivity toward Hg(2+) ion with no complexation being observed towards zinc and alkali metals. The extracted and the complexing cation percentages were determined by atomic absorption measurements.

A novel adsorbent for heavy metals, functionalized with conjugated β-ketoenol Furan, was fabricated using a simple heterogeneous method. The adsorbent design (SiNFn) was well analyzed and characterized by the techniques of solid state 13C NMR, Fourier transform-infrared spectroscopy (FT-IR), elementary analysis, nitrogen adsorption–desorption isotherm, BET surface area, BJH pore sizes, and scanning electron microscopy (SEM). The new surface has good thermal stability determined by thermogravimetry curves analysis (TGA), and a good chemical stability investigated in various acidic and buffer solutions. The effect of various parameters on Cd(II), Cu(II), Zn(II), and Pb(II) adsorption, such as pH, concentration, temperature, competitive extraction, thermodynamics and kinetics studies, and extraction of metals from real water samples were investigated. The results indicated that the adsorption efficiency increases with increasing pH and follows pseudo-second-order kinetics. Adsorption was rapid as evidenced b...

International audience; A pyridylpyrazole bearing a hydroxyethyl substituent group has been synthesized by condensation of (Z)-4-hydroxy-4-(pyridin-2-yl)but-3-en-2-one with 2-hydroxyethylhydrazine. The compound was well characterized and its structure confirmed by single crystal X-ray diffraction. Density functional calculations have been performed using DFT method with 6-31G* basis set. The HOMO-LUMO energy gap, binding energies and electron deformation densities are calculated at the DFT (BLYP, PW91, PWC) level. The electrophilic f(´) and nucleophilic f(+) Fukui functions and also the electrophilic and nucleophilic Parr functions are well adapted to find the electrophile and nucleophile centers in the molecule. The title compound has been tested for its DPPH radical scavenging activity which is involved in aging processes, anti-inflammatory, anticancer and wound healing activity. Compound is also found with a significant antioxidant activity, probably due to the ability to donate a hydrogen atom to the DPPH radical.

C14H18N4O2, monoclinic, P21/c (no. 14), a = 4.4260(9) Å, b = 14.502(4) Å, c = 11.455(3) Å, β = 96.319(5)°, V = 730.8(3) Å3, Z = 2, R gt (F) = 0.0712, wR ref (F 2 ) = 0.1946, T = 296(2) K.