Removal of Dichromate Anions with Nanofiltration‐Complexation by using Amino Calix[4]arene Derivative

Abstract

Herein the removal and recovery of chromium anions from aqueous solutions by using nanofiltration pilot‐scale equipment (Osmonics Sepa CF Membrane Cell) with a water‐soluble amino calix[4]arene derivative was studied. To understand the selectivity, the authors also examined the retention of chromium anions in the presence of Cl^?, NO₃ ^?, SO₄ ^2?, HSO₄ ^?, CO₃ ^2?, PO₄ ^3?, H₂PO₄ ^? anions in nanofiltration‐complexation. From the results water‐soluble amino calix[4]arene was effective and selective ligand for dichromate anions over nitrate anions, in a nanofiltration‐complexation system at pH 2.5. Moreover, the recovery and reusability studies of dichromate and nitrate anions and also ligand were performed.     

Elucidating the thermal degradation of carbazole-containing platinum–polyyne polymers

In this article, we present the significant influence of the substitution pattern of carbazole on the thermal stability of carbazole-containing platinum(II)–polyyne polymers. A series of the studies on the dynamic and isotherm conditions revealed a better thermal stability for the 3,6-carbazole based platinum(II)–polyyne polymer (36CbzPtP), where alkynes were located at the p-phenylene positions relative to the carbazole nitrogen atom, compared to that for the 2,7-carbazole based counter polymer (27CbzPtP), where the alkynes were located at the m-phenylene positions relative to the carbazole nitrogen atom. On the other hand, the thermogravimetry–mass spectrometry–Fourier transform infrared technique applied to the two polymers revealed the same degradation mechanism, which probably involved the thermal decomposition of triethyl phosphine moieties and which was followed by the C C scission of hexadecyl chains. The carbazole moieties eventually underwent degradation when the temperature exceeded 415 °C. Molecular modeling showed that polymer 27CbzPtP formed a linear structure, whereas polymer 36CbzPtP adopted a curved structures; this led to different packing modes of the polymer chains. This structural difference affected the efficiency of the initial degradation event of the triethyl phosphine groups. The curved structures of 36CbzPtP sterically protected the triethyl phosphine groups; this led to an increased thermal stability over that of 27CbzPtP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47639.     

Impact of Tetracationic Calix[4]arene Conformation—from Conic Structure to Expanded Bolaform—on Their Antibacterial and Antimycobacterial Activities

The four possible conformers of a new tetrakisguanidino calix[4]arene thought to interact deleteriously with bacterial membranes have been synthesized, characterized, and evaluated for their in vitro cytotoxicity and antibacterial activity against various reference Gram-negative and Gram-positive bacteria, as well as Mycobacterium tuberculosis. It appears that reversal of at least one phenolic unit results in clear increases in their activities. This can be attributed to the evolution towards bolaform structures, which are able to interact more deeply with the bacterial membrane. Indeed, the 1,3-alternate conformer 16 exhibits the best antibacterial activity (MIC<1.0 μg mL⁻¹ on Staphylococcus aureus). Moreover, 16 displays very good antibacterial activities against an isoniazid-resistant strain of M. tuberculosis (MIC=1.2 μg mL⁻¹), associated with the lowest cytotoxicity, thus making it the most potent compound of the series; this could open new ways of research in the field of anti-infective drug development to meet the huge current demand.     

π-conjugated polymers containing pendant Mn12 cluster: Synthesis and physical properties

In this paper two conjugated polymers containing polyfluorene chain with pendant carboxyl group (P1 and P2) are synthesized via Suzuki reaction, and then two corresponding polymers containing the pendant Mn₁₂ cluster core (Mn₁₂-P1 and Mn₁₂-P2) are obtained through exchange of the pendant carboxyl group in the polymers with acetate ligand of Mn₁₂-Ac. All the polymers show similar UV–vis absorption spectra with maximum peak at 388 nm and fluorescence emission spectra with maximum peak at 419 nm and a shoulder at 443 nm that can be attributed to the polyfluorene chain. The cyclic voltammetry measurement indicates that Mn₁₂-P1 or Mn₁₂-P2 exhibit similar electrochemical behavior to that of the corresponding P1 or P2. These indicate that the introduction of Mn₁₂ cluster at the side-chain of the conjugated polymers has little influence on the photophysical and electrochemical properties of the conjugated main-chain. However, compared with pristine Mn₁₂-Ac the magnetic properties of the modified Mn₁₂ cluster has been changed after substitution of acetate group by the pendant carboxyl group of the polymer. Both of the Mn₁₂ clusters modified by the conjugated polymer (Mn₁₂-P1 and Mn₁₂-P2) show paramagnetism in the range of 2–300 K, and no SMM magnetic behavior is observed at low temperature.     

Extraction of Cesium by a Calix[4]arene‐Crown‐6 Ether Bearing a Pendant Amine Group

Abstract

The goal of this work was to evaluate the role of the amino group of 5‐aminomethylcalix[4]arene‐[bis‐4‐(2‐ethylhexyl)benzo‐crown‐6] (AMBEHB) in the extraction of cesium from acidic and basic mixtures of sodium nitrate and other concentrated salts. The extraction of cesium from nitrate media was measured as a function of extractant concentration, nitrate concentration, cesium concentration, and pH over the range 1–13. The initial studies showed a moderate decrease in the extraction of cesium in acidic media, which indicated the binding of cesium by the calixarene‐crown was weakened by the protonation of the amine group. The results also indicated that a 1∶1∶1 Cs‐ligand‐nitrate complex is formed in the organic phase. To further evaluate AMBEHB, the empirical data were mathematically modeled to determine the formation constants of the complexes formed in the organic phase. The resulting formation constants showed that the attachment of the amine group to the calixarene‐crown molecule reduced the binding stability for the cesium ion upon contact with an acidic solution. This supports the hypothesis of charge repulsion as the basis for more efficient stripping of cesium via pH‐switching.     

Liquid–Liquid Extraction of Alkali Metal Cations by Calix[4]crowns with Pendant Groups

Abstract

The selective liquid–liquid extraction of alkali metal cations from the aqueous phase to the organic phase was carried out by using calix[4]crowns bearing two pendant groups with donor sites. It was found that calix[4]crown‐4 and calix[4]crown‐5 extractants with two pendant groups exhibit higher extraction efficiency than the parent compounds and possess obvious selectivity for Na⁺ and K⁺, respectively.     

Synthesis and photovoltaic properties of donor–acceptor polymers incorporating a structurally-novel pyrrole-based imide-functionalized electron acceptor moiety

A structurally-novel pyrrole-based imide-functionalized electron accepting monomer unit, 4,6-dibromo-2,5-dioctylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (DPPD), was prepared. The new DPPD unit was copolymerized with pyrrole-based electron rich monomers, such as thiophene-(N-alkyl)pyrrole-thiophene (TPT) and fused thiophene-(N-alkyl)pyrrole-thiophene (DTP) derivatives, to afford two new polymers, namely P(TPT-DPPD) and P(DTP-DPPD), respectively. The two polymers showed a strong absorption band at 300–600 nm and 300–650 nm, respectively, and their calculated optical band gaps were 2.09 eV and 1.89 eV, respectively. The electrochemical analysis reveals that the highest occupied molecular orbital (HOMO) energy levels of P(TPT-DPPD) and P(DTP-DPPD) were positioned at −5.55 eV and −5.24 eV, respectively, whereas their lowest unoccupied molecular orbital (LUMO) energy levels were positioned at −3.46 eV and −3.35 eV, respectively. The preliminary photovoltaic properties of the polymers, P(TPT-DPPD) and P(DTP-DPPD), were examined by fabricating polymer solar cells (PSCs) with each polymer as an electron donor and PC₇₁BM as an electron acceptor. The PSCs fabricated with the configuration of ITO/PEDOT:PSS/P(TPT-DPPD) or P(DTP-DPPD):PC₇₁BM/LiF/Al showed maximum power conversion efficiency (PCE) of 0.73% and 1.64%, respectively.     

Highly π-extended polymers based on phenanthro-pyrazine: Synthesis,characterization, theoretical calculation and photovoltaic properties

Two novel narrow bandgap conjugated polymers containing phenanthro-pyrazine unit have been successfully synthesized by the Stille coupling reaction. Comparing to the common polymers containing dithiophen-quinoxaline or dithiophen-thieno[3,4-b]pyrazine moiety, the conjugation degree of these new polymers is extended through the direction perpendicular to the main chain by introducing phenanthrene-9,10-dione to maintain a rigid conjugated bridge. The obtained polymers exhibit solution-processing ability, high thermal stabilities, broad visible absorption bands and narrow optical bandgaps. Theoretical studies disclose that the P2 exhibits wholly coplanar conformation in 1-D and 2-D direction, and the PCE value is 6-folded higher than P1 under the same photovoltaic measurement condition.     

A new POMOF consisting of [VW12]4 − clusters and metal-organic nanotubes: Synthesis,structure, electrocatalytic and luminescent properties

A novel compound, [Co₂(bimb)₂VW₁₂O₄₀] [bimb]·6H₂O (1) (bimb = 1.4-bis(1-imidazolyl)benzene), with polyoxometalate-based metal-organic framework (POMOF), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, infrared spectrum, X-ray photoemission spectra, elemental analyses, and powder X-ray diffraction pattern. In the compound, there are metal-organic nanotubes formed by [Co₂(bimb)] ^4 + zig-zag chains and six-connected VW₁₂ guest clusters. Further, the neighboring metal-organic nanotubes are connected together via sharing the [Co₂bimb]^4 + zig-zag chains to achieve a highly opened POMOF with hexagonal apertures, representing the first POMOF constructed by V-centered tungstovanadate. Electrochemical and luminescent properties of the compound were also investigated.     

Synthesis and properties of nonlinear optical chromophores and polymers containing 6-nitroquinoline as π-electron acceptor

Summary Two nonlinear optical (NLO) methacrylate monomers, 2-methyl-acrylic acid 2-(ethyl-{4-[2-(6-nitro-quinolin-2-yl)-vinyl]-phenyl}-amino)-ethyl ester (5) and 2-methyl-acrylic acid 6-{3-[2-(6-nitro-quinolin-2-yl)-vinyl]-carbazol-9-yl}-hexyl ester (7) were newly synthesized and copolymerized with methylmethacrylate to give NLO polymers, P1 and P2. These polymers were well soluble in organic solvents and showed glass transition temperatures at 145 °C and 114 °C, respectively. The number average molecular weights (Mn) were 26,600 for P1 and 9,300 for P2. The SHG coefficients (d₃₃) of corona-poled films of P1 and P2 measured with 1.064 μm Nd-YAG laser were 32.2 pm/V and 17.6 pm/V, respectively. Received: 29 September 1998/Revised version: 7 December 1998/Accepted: 11 December 1998     

Synthesis and optical properties of π-conjugated polymers composed of diester-substituted bithiophene and dibenzothiophene or carbazole

Novel π-conjugated polymers composed of diester-subsituted bithiophene and dibenzothiophene (PDBT-DEBT) or N-alkyl carbazole (PCz-DEBT) were prepared via the Stille cross-coupling polymerization using Pd(0) catalyst. The structures of obtained polymers were confirmed by ¹H NMR and IR spectroscopies. Optical properties of the polymers were investigated by UV–vis and photoluminescence spectroscopies. The photoluminescence spectra of the polymers showed strong emission peaks in the green region.     

Photoactive ternary Tb3+/Zn2+ centered hybrids with p-tert-butylcalix[4]arene functionalized Si–O bridge and polyvinylpyridine

A new multifunctional linkage Calix-AC-Si is derived from the modification of the p-tert-butylcalix[4]arene derivative with 3-(triethoxysilyl)-propyl isocyanate (TEPIC) and behaves as the first chelated ligand, and the organic polymer polyvinylpyridine (PVPD) is used as the second terminal ligand, whose ternary hybrids of metal ions (Tb³⁺ and Zn²⁺) are assembled and possess different luminescent properties. Especially the introduction of Zn²⁺ in the Tb³⁺ hybrid system can improve the luminescence of Tb³⁺.     

Synthesis of π-conjugated polymers bearing electronic and optical functionalities by organometallic polycondensations and their chemical properties

A wide variety of π-conjugated polymers have been synthesized by using organometallic polycondensations. For instance, Ni(0) complex-promoted dehalogenative polycondensation of dihaloaromatic compounds, X-Ar-X, affords poly(arylene)s, -(Ar)_n-. Pd-catalyzed polycondensation gives alternating copolymers, -(Ar-Ar′)_n-, and poly(arylene-ethynylene)s, -(Ar-CC-Ar′-CC)_n-. These polymers show distinguishing optical and electrochemical properties and functionalities. Their well-characterized linear structures lead to molecular assembly and packing of the polymer molecules in solutions and in the solid state. In this article, we describe the synthesis of π-conjugated polymers by the organometallic polycondensations, chemical properties of the synthesized polymers, and applications of the polymers for electronic and optical devices.     

Hemicucurbit[n]urils and Their Derivatives – Synthesis and Applications

The first hemicucurbit[n]uril macrocycles were described in 2004, and since then a series of functionalised hemicucurbit[n]uril derivatives have been prepared and studied. The original hemicucurbit[n]urils suffer from sparse solubility, which limits their applications in supramolecular chemistry. Recent progress in the synthesis of a range of derivatives such as the biotin[n]urils, the bambus[n]urils, and the cyclohexylhemicucurbit[n]urils have enabled studies of the supramolecular chemistry of the hemicucurbituril system, both in water and in a range of organic solvents. In contrast to the popular cucurbit[n]uril macrocycles that are state-of-the-art hosts for cations, the hemicucbit[n]urils host anions. Herein we provide a survey of the literature covering the syntheses of the hemicucurbituril derivatives and their supramolecular chemistry.     

Synthesis and properties of high-performance and good water-soluble melamine–formaldehyde resin

In this article, high-sulfonated melamine–formaldehyde (HSMF) resins were prepared with a sulfite/melamine (S/M1.5) molar ratio. During the sulfonation process, the reaction temperature and the added velocity of sodium bisulfite affecting the properties of the resin were studied. In the condensation stage, where the pH range is 6.0 and the temperature is about 25°C, the condensation time was prolonged above 24 h. The stability and water solubility of the resin was improved greatly. It is an effective superplasticizer at small dosages of admixture. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3268–3271, 2001     

Synthesis of well-defined norbornene–lactone-functionalized polymers via ATRP

Well-defined norbornene–lactone-functionalized polymers were synthesized by atom transfer radical polymerization (ATRP) of 5-methacryloxy-6-hydroxynorbornene-2-carboxylic-6-lactone (MNL) and 5-acryloxy-6-hydroxynorbornene-2-carboxylic-6-lactone (ANL) monomers. The ATRP of MNL initiated by ethyl 2-bromopropionate (EBrP), in both N,N-dimethylformamide (DMF) and o-dichlorobenzene (ODCB) solvents was successfully carried out in the presence of CuCl/CuBr and N,N,N′′,N′′,N′′-pentamethyltriethylenetetramine (PMDETA) at 70 °C. The CuCl/ODCB catalyst system gave rise to a lower M _w/M _n (≦1.20) than CuBr/DMF catalyst system. The ATRP of ANL was feasible in the presence of CuBr and PMDETA at 70 °C but showed lower reactivity than MNL. The resulting polymers were characterized by means of gel permeation chromatography (GPC) and ¹H NMR spectroscopy.     

Synthesis and properties of poly[2-(4′-oxyphenylene)-5-benzimidazole] and a proton-exchange membrane produced on its basis

A monomer of the A-B type, 3,4-diamino-4′-carboxydiphenyloxide, has been synthesized via a series of consecutive transformations of 5-chloro-2-nitroaniline. The homopolycondensation of the monomer in Eaton’s reagent at 140°C yields poly[2-(4′-oxyphenylene)-5-benzimidazole] soluble in organic solvents. A membrane containing 51% H₃PO₄ (2.9 acid molecules pert monomer unit) and possessing a proton conductivity of 0.025 S/cm at 160°C is produced by doping a polymer film with 60% H₃PO₄.     

Synthesis,processing and properties of TaC–TaB2–C ceramics

Multi-phase ceramics in the TaC–TaB₂–C system were prepared from TaC and B₄C mixtures by reactive pressureless sintering at 1700–1900 °C. The pressureless densification was promoted by the use of nano-TaC and by the presence of active carbon in the reaction products. The presence of TaB₂ inhibited grain growth of TaC and increased the hardness compared to pure TaC. If a coarse TaC powder was used, the compositions did not densify. In contrast, pure nano-TaC was pressureless sintered at 1800 °C by the addition of 2 wt.% carbon introduced as carbon black or graphite. The introduction of carbon black resulted in fully dense TaC ceramics at temperatures as low as 1500 °C. The grain size of nominally pure TaC ceramics was a strong function of carbon stoichiometry. Enhanced grain size in sub-stoichiometric TaC, compared to stoichiometric TaC, was observed. Additional work is necessary to optimize processing parameters and evaluate the properties of ceramics in the TaC–TaB₂–C system.     

Synthesis and microwave absorption properties of Ni–Zn–Mn spinel ferrites

A series of Ni_0·5?xZn_0·3?xMn_0·2+2xFe₂O₄ ferrites was successfully prepared by the sol–gel autocombustion method. The structure and electromagnetic properties of the powders were characterised by X-ray diffraction, SEM and vector network analysis. The pure powders were formed by heating at 1200°C for 3 h in air, and grain sizes increased as the amount of substitution ranged from x?=?0·0 to x?=?0·25. For samples with x?=?0·1, a minimum reflection loss of ?27·57 dB was observed at 11·0 GHz with the less than ?10 dB absorption bandwidth at 8·0 GHz with 3·8 mm thickness. The results indicate that substitution with Mn and Zn ions can greatly improve the microwave absorption properties of NiFe₂O₄ ferrites.     

One-dimensional salen-type heterospin trimetallic (3d–4f–3d′) chain-like coordination polymers: Syntheses,crystal structures and magnetic properties

Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H₂O)}Ln(MeOH)(H₂O)₂{(μ-CN)₂Fe(CN)₄}]·2H₂O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)₆]^3? ions (H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)₆]^3? ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form.