Well‐Defined Amphiphilic C60‐PEG Conjugates: Water‐Soluble and Thermoresponsive Materials

For the preparation of well‐defined H₂O‐soluble C₆₀ polymers, several C₆₀‐PEG conjugates were prepared from a C₆₀ biscarboxylic acid derivative and monodisperse NH₂‐PEGs (NH₂‐EG_n, n = 4 – 36) via amide conjugation. When the relatively long PEGs (EG_n, n ≥ 12) were employed, the C₆₀‐PEG conjugates became completely H₂O‐soluble by forming micelle‐like structure shown by the data of surface tension, DLS, and cryo‐TEM. Interestingly, these H₂O‐soluble C₆₀‐PEG conjugates (C₆₀(EG_n)₂, n = 12 – 36) showed reversible thermoresponse to form larger aggregates (ca. 1 μm by DLS) at higher temperatures. The temperature for the aggregation was related to the lengths of PEGs attached to C₆₀; 29 °C (C₆₀(EG_n)₂, n = 12), 51 °C (n = 20), and 72 °C (n = 36). This thermoresponse was speculated to occur by dehydration of well‐organized PEG chains in the micelle‐type structure of monodisperse C₆₀‐PEG caused by gauche‐to‐anti conformational change of PEG anchors. This thermoresponse of well‐defined amphiphilic C₆₀‐PEG conjugates indicates potential applications in areas such as temperature sensors and thermoresponsive materials.     

Cyclodextrins in Polymer Synthesis: Photoinitiated Free‐Radical Polymerization of N‐Isopropylacrylamide in Water Initiated by a Methylated β‐Cyclodextrin/2‐Hydroxy‐2‐methyl‐1‐phenylpropan‐1‐one Host/Guest Complex

Methylated β‐cyclodextrin (Me‐β‐CD) was used to complex a free‐radical photoinitiator, 2‐hydroxy‐2‐methyl‐1‐phenylpropan‐1‐one ( 1 ), yielding the water‐soluble 1 : 1 host/guest complex 1 a . The structure of complex 1 a was verified by means of IR, UV/vis and ¹H NMR spectroscopy. The influence of Me‐β‐CD as the host on the photopolymerization kinetics of N‐isopropylacrylamide was studied. Compared to the photopolymerization carried out under nearly identical conditions but without cyclodextrin, an increase in the polymerization rate was registered in the presence of complex 1 a .     

Validation of a high‐performance liquid chromatography method for the determination of (−)‐α‐bisabolol from particulate systems

A reversed‐phase high performance liquid chromatography method has been developed and validated for determination and quantitation of the natural sesquiterpene (−)‐α‐bisabolol. Furthermore the application of the method was done by characterization of chitosan milispheres and liposomes entrapping Zanthoxylum tingoassuiba essential oil, which contains appreciable amount of (−)‐α‐bisabolol. A reversed‐phase C₁₈ column and gradient elution was used with the mobile phase composed of (A) acetonitrile–water–phosphoric acid (19:80:1) and (B) acetonitrile. The eluent was pumped at a flow rate of 0.8 mL/min with UV detection at 200 nm. In the range 0.02–0.64 mg/mL the assay showed good linearity (R² = 0.9999) and specificity for successful identification and quantitation of (−)‐α‐bisabolol in the essential oil without interfering peaks. The method also showed good reproducibility, demonstrating inter‐day and intra‐day precision based on relative standard deviation values (up to 3.03%), accuracy (mean recovery of 100.69% ± 1.05%) and low values of detection and quantitation limits (0.0005 and 0.0016 mg/mL, respectively). The method was also robust for showing a recovery of 98.81% under a change of solvent in standard solutions. The suitability of the method was demonstrated by the successful determination of association efficiency of the (−)‐α‐bisabolol in chitosan milispheres and liposomes. Copyright © 2009 John Wiley & Sons, Ltd.     

Competitive heavy metal removal by poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid‐co‐itaconic acid)

The competitive removal of Pb²⁺, Cu²⁺, and Cd²⁺ ions from aqueous solutions by the copolymer of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and itaconic acid (IA), P(AMPS‐co‐IA), was investigated. Homopolymer of AMPS (PAMPS) was also used to remove these ions from their aqueous solution. In the preparation of AMPS–IA copolymer, the molar percentages of AMPS and IA were 80 and 20, respectively. In order to observe the changes in the structures of polymers due to metal adsorption, FTIR spectra by attenuated total reflectancetechnique and scanning electron microscopy (SEM) pictures of the polymers were taken both before and after adsorption experiments. Total metal ion removal capacities of PAMPS and P(AMPS‐co‐IA) were 1.685 and 1.722 mmol Me²⁺/g_polymer, respectively. Experimental data were evaluated to determine the kinetic characteristics of the adsorption process. Competitive adsorption of Pb²⁺, Cu²⁺, and Cd²⁺ ions onto both PAMPS and P(AMPS‐co‐IA) was found to fit pseudo‐second‐order type kinetics. In addition, the removal orders in the competitive adsorption of these metal ions onto PAMPS and P(AMPS‐co‐IA) were found to be Cd²⁺ > Pb²⁺ > Cu²⁺ and Pb²⁺ > Cd²⁺ > Cu²⁺, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Cobalt‐based metal coordination polymers with 4,4′‐bipyridinyl groups: highly efficient catalysis for one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions

Three new metal coordination complexes, namely [Co(BPY)₂(H₂O)₂](BPY)(BS)₂(H₂O)₄ ( 1 ), [Co(BPY)₂(H₂O)₄](ABS)₂(H₂O)₂ ( 2 ) and [Co(BPY)(H₂O)₄](MBS)₂ ( 3 ) (BPY = 4,4′‐bipyridine, BS = phenylsulfonic acid, ABS = p‐aminobenzenesulfonic acid, MBS = p‐methylbenzenesulfonic acid), were obtained under hydrothermal conditions. Complexes 1 , 2 , 3 were structurally characterized using single‐crystal X‐ray diffraction and infrared spectroscopy. All of them display low‐dimensional motifs: complex 1 displays a two‐dimensional structure; and complexes 2 and 3 exhibit a one‐dimensional tape structure. Through strong intermolecular hydrogen bonding interactions and weak packing interactions, all of them further stack to generate a three‐dimensional supramolecular architecture. Catalysts 1 , 2 , 3 were involved in the green synthesis of a variety of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions through Biginelli reactions. The corresponding catalytic product was obtained in quantitative yields (99%) under eco‐friendly synthesis conditions for the variety of reactions. Catalysts 1 , 2 , 3 exhibit excellent efficiency for the desired product, and their catalytic performance shows the following order: 2  >  1  ≈  3 , which can be ascribed to the hydrophobic interactions of different phenylsulfonate groups. The catalytic performance for the Biginelli reaction is not only dependent on the selected solvents, but also inversely proportional to the polarities of the solvents. Copyright © 2016 John Wiley & Sons, Ltd.     

Cationic para‐phenyl‐substituted α‐diimine nickel catalyzed ethylene and 4‐methyl‐1‐pentene (co)polymerizations via living/controlled chain‐walking

Upon activation with diethylaluminium chloride (Et₂AlCl), a series of phenyl‐substituted α‐diimine nickel precatalysts conducted 4‐methyl‐1‐pentene (4MP) and ethylene (E) (co)polymerizations via controlled chain‐walking to generate branched amorphous polymers with high molecular weight and narrow molecular weight distribution (M_w/M_n < 1.6). The obtained poly(4MP)s were amorphous elastomers with glass transition temperature (T_g) of ?10 ~ ?24 °C, which are higher than that of E‐4MP copolymer ( ? 63.0 °C). At room temperature (25 °C), 4MP polymerization proceeds in a living manner. The microstructures of the produced poly(4MP)s indicated the 2,1‐ and 1,2‐insertion followed by chain‐walking, the latter being predominant. The NMR analyses of the polymers showed that the obtained poly(4MP) possessed methyl, isobutyl, 2,4‐dimethylpentyl and 2‐methylhexyl groups, while the isobutyl and 2,4‐dimethylalkyl branches derived from 4MP were observed in the E‐4MP copolymer. The branch structures and the insertion‐type of monomer were depended on the polymerization temperature, and the content of methyl branch increased with an increase in the polymerization temperature.     

Alternative Synthesis of 2‐Hydroxy‐3,5,5‐trimethylcyclopent‐2‐en‐1‐one

The 2‐hydroxy‐3,5,5‐trimethylcyclopent‐2‐en‐1‐one ( 1 ) was synthesized in 42% yield by rearrangement of epoxy ketone 10 on treatment with BF₃⋅Et₂O under anhydrous conditions. Intermediate 10 was available from the known enone 8 , either via direct epoxidation (60% H₂O₂, NaOH, MeOH; yield 50%), or via reduction to the corresponding allylic alcohol 14 (LiAlH₄, THF), followed by epoxidation ([VO(acac)₂], ^tBuOOH) and reoxidation under Swern conditions, in 37% total yield.     

Enhancing the electroluminescent efficiency of poly{5‐methoxy‐2‐[(2′‐ethyl‐hexyl)‐oxy]‐p‐phenylenevinylene}/poly(2,3‐diphenyl‐5‐octyl‐p‐phenylenevinylene) polyblends by the introduction of chemical bonding through a thermal treatment

A significant improvement in the electroluminescence (EL) properties was observed for a poly{5‐methoxy‐2‐[(2′‐ethyl‐hexyl)‐oxy]‐p‐phenylenevinylene} (MEH–PPV)/poly(2,3‐diphenyl‐5‐octyl‐p‐phenylenevinylene) (DPO–PPV) blend after a thermal treatment at 200 °C for 2 h in vacuo to furnish the chemical bonding between polymer chains. ¹H NMR spectroscopy and two‐photon excitation microscopy revealed that the chemical bonding turned the immiscible polyblend into a system more like a block copolymer with a vertically segregated morphology. Because both the lowest unoccupied molecular orbital and highest occupied molecular orbital levels of MEH–PPV in the wetting layer were higher than those of DPO–PPV in the upper layer, the heterojunction between the two layers of the polymers fit the category of so‐called type II heterojunctions. As a result, the turn‐on voltage of the polymer light‐emitting diode prepared with the thermally treated polyblend decreased to ～0.6 V, and the EL emission intensities and quantum efficiencies increased to about 4 times those of the untreated polyblend. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 62–69, 2006     

1‐Amino‐2‐fluoromonocarba‐closo‐dodecaborates: K[1‐H2N‐2‐F‐closo‐1‐CB11H10] and [Et4N][1‐H2N‐2‐F‐closo‐1‐CB11I10]

The potassium salt of the [1‐H₂N‐2‐F‐closo‐1‐CB₁₁H₁₀]^– anion ( 1 ) was obtained from an insertion reaction of Li₃[7‐H₂N‐nido‐7‐CB₁₀H₁₀] with BF₃ · OEt₂. Anion 1 was protonated to the neutral species 1‐H₃N‐2‐F‐closo‐1‐CB₁₁H₁₀ (H 1 ) and it was iodinated with ICl to the [1‐H₂N‐2‐F‐closo‐1‐CB₁₁I₁₀]^– anion ( 2 ). All species were characterized by multinuclear NMR, IR, and Raman spectroscopy as well as by elemental analysis. The structure of H 1· (CH₃)₂CO was studied by single‐crystal X‐ray diffraction and the experimentally determined bond lengths are compared to values derived from density functional calculations.     

Short communication: An alternative and effective catalyst in the stereo‐specific reaction of Z‐1‐aryl‐1‐stannyl‐2‐silylethenes with allyl bromide

The Pd(dba)₂‐catalyzed reaction of Z‐1‐aryl‐1‐(tributylstannyl)‐2‐(trimethylsilyl)ethenes with allyl bromide in the presence of copper(I) iodide is reported for the first time. The reaction in the presence of 0.5 mol% Pd(dba)₂ and 8 mol% CuI in dimethylformamide takes place at room temperature to give E‐2‐aryl‐1‐(trimethylsilyl)penta‐1,4‐dienes exclusively in isolated yields of 62–99%. A putative reaction mechanism is proposed. Copyright © 2005 John Wiley & Sons, Ltd.     

A comparative study of two polymorphs of bis(1‐hydroxy‐2‐methylpropan‐2‐aminium) carbonate

Alkanolamines have been known for their high CO₂ absorption for over 60 years and are used widely in the natural gas industry for reversible CO₂ capture. In an attempt to crystallize a salt of (RS)‐2‐(3‐benzoylphenyl)propionic acid with 2‐amino‐2‐methylpropan‐1‐ol, we obtained instead a polymorph (denoted polymorph II) of bis(1‐hydroxy‐2‐methylpropan‐2‐aminium) carbonate, 2C₄H₁₂NO⁺·CO₃²⁻, (I), suggesting that the amine group of the former compound captured CO₂ from the atmosphere forming the aminium carbonate salt. This new polymorph was characterized by single‐crystal X‐ray diffraction analysis at low temperature (100 K). The salt crystallizes in the monoclinic system (space group C2/c, Z = 4), while a previously reported form of the same salt (denoted polymorph I) crystallizes in the triclinic system (space group P, Z = 2) [Barzagli et al. (2012). ChemSusChem, 5 , 1724–1731]. The asymmetric unit of polymorph II contains one 1‐hydroxy‐2‐methylpropan‐2‐aminium cation and half a carbonate anion, located on a twofold axis, while the asymmetric unit of polymorph I contains two cations and one anion. These polymorphs exhibit similar structural features in their three‐dimensional packing. Indeed, similar layers of an alternating cation–anion–cation neutral structure are observed in their molecular arrangements. Within each layer, carbonate anions and 1‐hydroxy‐2‐methylpropan‐2‐aminium cations form planes bound to each other through N—H…O and O—H…O hydrogen bonds. In both polymorphs, the layers are linked to each other via van der Waals interactions and C—H…O contacts. In polymorph II, a highly directional C—H…O contact (C—H…O = 156°) shows as a hydrogen‐bonding interaction. Periodic theoretical density functional theory (DFT) calculations indicate that both polymorphs present very similar stabilities.     

Embryotoxicity studies of tri‐n‐butyltin(IV) complexes of 5‐[(E)‐2‐(aryl)‐1‐diazenyl]‐2‐hydroxybenzoic acid and 2‐[(E)‐2‐(3‐formyl‐4‐hydroxyphenyl)‐1‐diazenyl] benzoic acid on sea urchin development

The toxicity studies of free 5‐[(E)‐2‐(aryl)‐1‐diazenyl]‐2‐hydroxybenzoic acid and 2‐[(E)‐2‐(3‐formyl‐4‐hydroxyphenyl)‐1‐diazenyl]benzoic acid and their tri‐n‐butyltin(IV) complexes were evaluated by using sea urchin early developmental stages as recommended model organisms for toxicity tests. The novel complexes, as the parent tri‐n‐butyltin(IV) chloride (TBTCl), caused mitosis block and induced high embryonic mortality in sea urchin. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of a new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxycarbonyl)aminobenzenesulfonamide and its copolymerization with N‐phenyl maleimide

The new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxy‐ carbonyl)aminobenzenesulfonamide (MPBAS) (M₁) is synthesized using sulfadiazine as parent compound. It could be homopolymerized and copolymerized with N‐phenyl maleimide (NPMI) (M₂) by radical mechanism using AIBN as initiator at 60 °C in dimethylformamide. The new monomer MPBAS and polymers were identified by IR, element analysis and ¹H NMR in detail. The monomer reactivity ratios in copolymerization were determined by YBR method, and r₁ (MPBAS) = 2.39 ± 0.05, r₂ (NPMI) = 0.33 ± 0.02. In the presence of ammonium formate, benzyloxycarbonyl groups could be broken fluently from MPBAS segments of copolymer by catalytic transfer hydrogenation, and the copolymer with sulfadiazine side groups are recovered. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2548–2554, 2000     

Efficient Synthesis of Novel 3‐Phenyl‐5‐thioxo‐3,4,5,6‐tetrahydroimidazo[4,5‐c]pyrazole‐2(1H)‐carbothioamide Derivatives Using a CeO2–MgO Catalyst and Evaluation of Antimicrobial Activity

Imidazo[4,5‐c ]pyrazole derivatives ( 3a–f , 4a–f , and 5a–f ) were efficiently synthesized by one‐pot three‐component reactions using CeO₂–MgO as the catalyst. The synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. The in vitro antimicrobial activity of the synthesized compounds against various bacterial and fungal strains was screened. Compound 3b was highly active [minimum inhibitory concentration (MIC): 0.5 μg/mL] against Gram‐positive Staphylococcus aureus , and compounds 3b , 3f , 4d , and 4e were highly active (MIC: 0.5, 2, 2, and 0.5 μg/mL, respectively) against Gram‐negative Pseudomonas aeruginosa and Klebsiella pneumoniae , relative to standard ciprofloxacin in the antibacterial activity screening. Compounds 3b and 4f were highly active (MIC: 4 and 0.5 μg/mL, respectively) against Aspergillus fumigatus and Microsporum audouinii in the antifungal activity screening compared with the clotrimazole standard.     

Preparative isolation and purification of 12 main antioxidants from the roots of Polygonum multiflorum Thunb. using high‐speed countercurrent chromatography and preparative HPLC guided by 1,1′‐diphenyl‐2‐picrylhydrazyl‐HPLC

A hyphenated strategy by off‐line coupling of 1,1′‐diphenyl‐2‐picrylhydrazyl‐high‐performance liquid chromatography, high‐speed countercurrent chromatography, and preparative high‐performance liquid chromatography was established to screen and separate antioxidants from ethyl acetate fraction of the roots of Polygonum multiflorum. Under the targeted guidance of 1,1′‐diphenyl‐2‐picrylhydrazyl‐high‐performance liquid chromatography experiment, 12 compounds were identified as potential antioxidants and readily isolated by high‐speed counter‐current chromatography and preparative high‐performance liquid chromatography. Ultraviolet spectroscopy, mass spectrometry, and ¹H NMR spectroscopy were employed to identify their structures, which were assigned as gallic acid ( 1 , 6.2 mg, 98.28%), catechin ( 2 , 8.8 mg, 90.69%), epicatechin ( 3 , 4.1 mg, 96.71%), polydatin ( 4 , 5.3 mg, 94.91%), 2,3,5,4′‐tetrahydroxy stilbene‐2‐Ο‐β‐D‐glucoside ( 5 , 20.2 mg, 95.23%), piceatannol ( 6 , 5.3 mg, 96.85%), rutin ( 7 , 5.4 mg, 97.92%), resveratrol ( 8 , 5.2 mg, 96.94%), isorhapontigenin ( 9 , 11.4 mg, 94.81%), hyperoside ( 10 , 9.7 mg, 98.52%), rhein ( 11 , 4.9 mg, 97.46%), and emodin ( 12 , 8.2 mg, 95.74%). Notably, compounds 6 and 9 were isolated from Polygonum multiflorum for the first time. In addition, antioxidant activity of compounds 1–12 were evaluated, and compounds 1–8 and 10 exhibited stronger antioxidant activity than ascorbic acid (positive control). These results indicated that the proposed method is a highly efficient strategy to screen and isolate antioxidants from complex natural products.     

Tautomeric behaviour and isotopic multiplets in the 13C NMR spectra of partially deuterated 5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones and 5‐arylazo‐2‐thioxo‐pyrimidine (1H,3H,5H)‐4,6‐diones—evidence for elucidation of tautomeric forms

NMR spectra of the synthesized azo dyes, 5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones (5a–g), 1,3‐dimethyl‐5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones (6a–g), and 5‐arylazo‐2‐thioxo‐pyrimidine (1H,3H,5H)‐4,6‐diones (7a–g) were studied in (CD₃)₂SO (three drops of CD₃OD were added into solutions of the dyes in two different concentrations). All dyes showed intramolecular hydrogen bonding. Dyes 5a–7a showed bifurcated intramolecular hydrogen bonds. Tautomeric behaviours of some of N‐methylated azo dyes (6a‐g) were studied in two different concentrations. The solvent–substrate proton exchange of dyes 5a–d, 6a and 7a–e was examined in presence of three drops of CD₃OD. The dyes which were soluble in (CD₃)₂SO containing CD₃OD showed isotopic splitting (β‐isotope effect) in the ¹³C NMR spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

A highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane as building block

Highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes via palladium‐catalyzed Suzuki–Miyaura cross‐coupling of (E)‐alkenyl iodides with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane ( 1 ) is reported. The vinylboronate pinacol ester ( 1 ) acts as a vinyl building block to show high chemoselectivity for the Suzuki–Miyaura pathway versus Heck coupling in the presence of biphasic conditions (Pd(PPh₃)₄, aqueous K₂CO₃, toluene and ethanol). Copyright © 2014 John Wiley & Sons, Ltd.     

Photoinduced and thermal reactions of α‐cyano‐β‐bromomethylcinnamide with 1‐benzyl‐1,4‐dihydronicotinamide

The photoinduced reaction of a mixture of (Z)‐α‐cyano‐β‐bromomethylcinnamide (1) and (E)‐α‐cyano‐β‐bromomethylcinnamide (2) with 1‐benzyl‐1, 4‐dihydronicotinamide produces a mixture of the (E)‐ and (Z)‐ isomers of α‐cyano‐β‐methylcinnamide (3 and 4). Using spin‐trapping technique for monitoring reactive intermediate, it is shown that the reaction proceeds via electron transfer‐debromination‐H abstraction mechanism. The thermal reaction of the same substrate with BNAH at 60°C in the dark gives three products: the (E)‐ and (Z)‐isomers of α‐cyano‐β‐methylcinnamide and a dehydrodimeric product; 2, 7‐dicyano‐3, 6‐diphenylocta‐2, 4, 6‐trien‐1, 8‐dioic amide (7). Based on product analysis, scavenger experiment and cyclic voltammetry, an electron transfer‐debromination‐disproportionation mechanism is proposed.     

Poly(9‐undecyl‐9‐methyl‐fluorene) and poly(9‐pentadecyl‐9‐methyl‐fluorene): Synthesis,solution structure,and effect of side chain asymmetry on aggregation behavior

We report on solution aggregates and backbone conformation of poly(9‐undecyl‐9‐methyl‐fluorene) (PF1‐11) and poly(9‐pentadecyl‐9‐methyl‐fluorene) (PF1‐15), having two different side chains compared with poly(9,9‐dihexylfluorene) (PF6) and poly(9,9‐dioctylfluorene) (PF8) with two identical side chains. In the poor solvent methylcyclohexane (MCH), X‐ray scattering indicates that PF1‐11 and PF1‐15 appear as three‐dimensional aggregates (5–10 nm wide and thick), forming ribbon‐like agglomerates (correlation lengths of 100 nm). PF6 and PF8 appear as two‐dimensional aggregates (>10 nm wide and 2–3 nm thick) involving ribbon‐like agglomerates (correlation lengths much greater than 100 nm). Upon heating, all aggregates undergo a gel–sol transition which occurs at lower temperatures for PF1‐11 and PF1‐15 (<60°C) than for PF6 and PF8 (>80°C). In the good solvent toluene, PF1‐11 and PF1‐15 form networks of cylindrical particles. The mesh size and the cylinder radius are smaller in 24°C toluene (60 nm, 0.5 nm) than in 60°C MCH (300 nm, 1–2 nm). Nuclear magnetic resonance spectra in toluene‐d₈ together with density functional theory calculations suggest higher torsion angles between polymer repeat units for PF6, PF8, and PF1‐11 (less planar conformation) and a gauche arrangement of the dihedral angles between the bridge carbon atom and the side chain methylene groups in PF1‐15. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 826–837     

Synthesis of α‐Aminonitriles and 5‐Substituted 1H‐Tetrazoles Using an Efficient Nanocatalyst of Fe3O4@SiO2–APTES‐supported Trifluoroacetic Acid

Fe₃O₄@SiO₂–APTES‐supported trifluoroacetic acid nanocatalyst was used for the one‐pot synthesis of α‐aminonitriles via a three‐component reaction of aldehydes (or ketones), amines, and sodium cyanide. This method produced a high yield of 75–96% using only a small amount of the catalyst (0.05 g) in EtOH at room temperature. The catalyst was also employed for the synthesis of 5‐substituted 1H‐tetrazoles from nitriles and sodium azide in EtOH at 80°C. The tetrazoles were produced with good‐to‐excellent yields in a short reaction time of 4 h. Both synthetic methods were carried out in the absence of an organic volatile solvent. Because the supported trifluoroacetic acid generated a solid acid on the surface, thus the acid corrosiveness was not a serious challenge. This heterogeneous nanocatalyst was magnetically recovered and reused several times without significant loss of catalytic activity.