Al Complexes Research Articles

Aggregation of trypsin and trypsin inhibitor by Al cation

Al cation may trigger protein structural changes such as aggregation and fibrillation, causing neurodegenerative diseases. We report the effect of Al cation on the solution structures of trypsin (try) and trypsin inhibitor (tryi), using thermodynamic analysis, UV–Visible, Fourier transform infrared (FTIR) spectroscopic methods and atomic force microscopy (AFM). Thermodynamic parameters showed Al-protein bindings occur via H-bonding and van der Waals contacts for trypsin and trypsin inhibitor. AFM showed that Al cations are able to force trypsin into larger or more robust aggregates than trypsin inhibitor, with trypsin 5±1 SE (n=52) proteins per aggregate and for trypsin inhibitor 8.3±0.7 SE (n=118). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced more alterations of trypsin inhibitor conformation than trypsin.

Salan group 13 complexes – structural study and lactide polymerisation

Herein the preparation and characterisation of a series of group 13 salan complexes, with a bipyrrolidine or N,N′-ethylenediamine backbone are disclosed. For the bipyrrolidine derived-salan ligand 1H2, the Al(III) and Ga(III) complexes are pseudo trigonal bipyramidal in the solid-state, whereas the In(III) complexes are best described as square based pyramidal structures. However, for the ethylenediamine derived-salan ligand 2H2, all complexes are effectively square based pyramidal in their structure. The complexes' solution behaviour is also investigated by NMR spectroscopic methods and it is observed that the solid-state structure is maintained in solution. The complexes have all been trialled for the ring opening polymerisation of rac-lactide. With In(1)Cl controlled polymerisation and narrow molecular weight distributions (1.01–1.08) are observed with heterotactic polylactide being prepared. Under the conditions tested the Ga(III) and Al(III) complexes were shown to be inactive.

Synthesis, Structural and Spectroscopic Study of Complexes of Tetradentate Schiff Base Derived from MalonylDihydrazide with Cr(III), Mn(II), Co(II), Cu(II) and Zn(II) Ions

This paper describes the synthesis of a new derivative dihydro-3H-indol-3-ylidene propane dihydrazide [L], which have been obtained from the reaction between malonyl di-hydrazide and an ethanollic solution of isatin. Tetradentatemacrocyclic ligand [L] was characterized by (C.H.N), (FT-IR), (UV-Vis), and 1H.NMR.A series of the used metal complexes have been synthesized by the prepared ligand [L] reaction with some transition metal ions. The isolated complexes were Cr(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) also characterized using different techniques such as (FT-IR), and (UV-Vis) spectroscopies, (C.H.N), flam atomic absorption in addition to the magnetic susceptibility and molar conductivity measurement. Al complexes were octahedral in geometry except for Zn (II) complex, which was tetrahedral.

Structural and magnetic properties of semiquinonate based Al(iii) and Ga(iii) complexes.

The reaction of anhydrous MCl3 (M = Al(iii) or Ga(iii)) with one-electron-reduced 3,5-di-tert-butyl-1,2-ortho-benzoquinone (using metallic sodium) led us to isolate two distinct metal complexes of Al(iii) and Ga(iii), which were structurally and magnetically characterized. Complex 1 crystallized in the monoclinic P21/n space group, whereas 2 crystallized in the triclinic P1[combining macron] space group. Interestingly, whereas the Al(iii) derivative was obtained as a dimer with the molecular formula [Al2(μ-HL-)2(L˙-)4] (1) (where L˙- is a semiquinonate radical and HL- is a monoanionic catecholate ligand), the Ga(iii) derivative crystallized as [Ga(L˙-)3] (2), which is a polymorph of a previously reported complex. The presence of both catecholate and/or semiquinonate ligands in 1 and 2 was confirmed by single-crystal X-ray diffraction, mass spectrometry, and NMR and infrared spectroscopy techniques. The crystalline phase purity of the complexes was confirmed by powder X-ray diffraction (PXRD). Measurements of direct-current magnetic susceptibility, which were performed on a polycrystalline samples, revealed that in both complexes the semiquinonate radical anions are coupled ferromagnetically via the diamagnetic metal ion. The magnetism data of both complexes were modelled using the Heisenberg-Van Vleck-Dirac (HDVV) Hamiltonian, and the extracted parameters are consistent with the literature reports. The details of the electronic structures of the ground states of 1 and 2 were further investigated via X-band (ca. 9 GHz) electron paramagnetic resonance (EPR). The EPR spectrum of 2 could be reproduced by considering a quartet ground state with zero-field splitting and hyperfine coupling, whereas attempts to simulate all the EPR spectral features observed in a frozen solution of 1 by assuming it was a pure phase failed. A correct simulation required the simultaneous inclusion of contributions from a quartet and a triplet state. This evidently suggests that the dimeric complex of 1 is in equilibrium with a monomeric [Al(L˙-)3] complex in solution.

Aluminum(i) β-diketiminato complexes activate C(sp2)-F and C(sp3)-F bonds by different oxidative addition mechanisms: a DFT study.

DFT computations reveal different reaction mechanisms for the oxidative addition of C(sp2)-F and C(sp3)-F bonds to the Al(i) complexes: a concerted mechanism for C(sp2)-F and a stepwise mechanism for C(sp3)-F involving fluoride transfer and the formation and recombination of an ion pair.

Investigation of the dinuclear effect of aluminum complexes in the ring-opening polymerization of ε-caprolactone

Al complexes bearing hydrazine-bridging Schiff base ligands showed the best catalytic activity, approximately 3- to 11-fold higher than that of dinuclear Al complexes bearing Salen ligands and mononuclear Al complexes bearing Schiff base ligands.

Synthesis Al complex and investigating effect of doped ZnO nanoparticles in the electrical and optical efficiency of OLEDS

In this study, an organometallic complex based on aluminum ions is synthesized. And it is utilized as fluorescent material in the organic light-emitting diodes (OLEDs). The synthesized complex was characterized using XRD, UV–Vis, FT-IR as well as PL spectroscopy analyses. The energy levels of Al complex were determined by cyclic voltammetry measurements. Then, the effects of ZnO nanoparticles (NPs) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, on the electrical and optical performance of the organic light-emitting diodes have been investigated. For this purpose, two samples containing ITO/PEDOT:PSS/PVK/Alq3/PBD/Al with two different concentration and two samples containing ITO/PEDOT:PSS:ZnO/PVK/Alq3/PBD/Al with two different concentration were prepared. Then, hole transport, electron transport and emissive layers were deposited by the spin coating method and the cathode layer (Al) was deposited by the thermal evaporation method. The OLED simulation was also done by constructing the model and choosing appropriate parameters. Then, the experimental data were collected and the results interpreted both qualitatively and quantitatively. The results of the simulations were compared with experimental data of the J–V spectra. Comparing experimental data and simulation results showed that the electrical and optical efficiency of the samples with ZnO NPs is appreciably higher than the samples without ZnO NPs.

Synthesis and herbicidal activity of optically active α-(substituted phenoxyacetoxy) (substituted phenyl) methylphosphonates

α-(Substituted phenoxyacetoxy) alkylphosphonates containing one chiral carbon atom have been demonstrated to be PDHc inhibitor with good herbicidal activity and some of them could be used as potential herbicide. In order to determine any difference in herbicidal activities between (R) and (S) isomers, the synthetic method of optically active substituted phenylalkylphosphonates IB were explored. A highly practical, enantioselective hydrophosphonylation was developed to prepare optically active O,O-dimethyl α-hydroxyalkylphosphonates 3 as key intermediate by asymmetric addition reaction of dimethylphosphite 1 and several kinds of aldehydes 2 using tridentate Schiff base Al(III) complexes as catalysts. A series of novel O,O-dimethyl α-(substituted phenoxyacetoxy)(substituted phenyl)methylphosphonates IB including (R) and (S) enantiomers were further synthesized with excellent enantioselectivity (95–99% ee) by the condensation of optically active α-hydroxyl (substituted phenyl)methylphosphonates 3 and substituted phenoxyacetyl chlorides 4. The herbicidal activities of title compound IB including their racemates, (R) and (S) enantiomers were evaluated in greenhouse for post-emergence application. All compounds IB showed significant inhibitory activity against dicotyledonous plants. A difference in herbicidal effect among racemate, (R) and (S) enantiomers were observed. Especially IB7 and IB10 showed obvious chiral selectivity in inhibitory activity against chickweed. (S)-IB7 with ED50 of 22.8gai/ha was found to be most effective enantiomer against chickweed and its inhibitory activity was 8.17 times higher than (R)-IB7. (S)-IB7 as potential herbicide would be effective at lower rates than (R)-IB7 or (rac)-IB7.

Two 5,5′-methylenebis(salicylaldehyde)-based Schiff base fluorescent sensors for selective sensing of Al3+ in DMSO/H2O solution

Two 5,5′-methylenebis(salicylaldehyde)-based Schiff base fluorescent sensors, 1 and 2, were synthesized. Sensors 1 and 2 both showed selective fluorescent sensing for Al3+ with low detection limits of 1.49×10−8 and 1.51×10−8M, respectively, in DMSO/H2O (19:1, v/v) solution at the pH value of 5.2. The 1:1 stoichiometries of the Al complexes were determined by Job plots and further verified with LC–MS data and 1H NMR studies. The sensing mechanisms of sensors 1 and 2 to Al3+ were proposed. The fluorescence color changes could be easily detected by the naked eye under a UV lamp.

Installing Heterobimetallic Cobalt–Aluminum Single Sites on a Metal Organic Framework Support

A heterobimetallic cobalt–aluminum complex was immobilized onto the metal organic framework NU-1000 using a simple solution-based deposition procedure. Characterization data are consistent with a maximum loading of a single Co–Al complex per Zr6 node of NU-1000. Furthermore, the data support that the Co–Al bimetallic complex is evenly distributed throughout the NU-1000 particle, binds covalently to the Zr6 nodes, and occupies the NU-1000 apertures with the shortest internode distances (∼8.5 A). Heating the anchored Co–Al complex on NU-1000 at 300 °C for 1 h in air completely removes the organic ligand of the complex without affecting the structural integrity of the MOF support. We propose that a Co–Al oxide cluster is formed in place of the anchored complex in NU-1000 during heating. Collectively, the results suggest that well-defined heterobimetallic complexes can be effective precursors for installing two different metals simultaneously onto a MOF support. The CoAl-functionalized NU-1000 samples catalyz...

Effects of Al(3+) Ions on Formation of Silica Framework and Surface Active Sites for SO4(2-) Ions.

Al(3+) ions were introduced into silica framework at 318 K in order to make active Al sites for SO4(2-) by the addition of aqueous sodium silicate solution to aqueous sulfuric acid solution of Al2(SO4)3. The (27)Al and (29)Si NMR spectra of aluminosilicates were measured at 278 K with reaction time. (29)Si NMR spectra were analyzed by the multivariate curve resolution. The addition of Al(3+) ions to aqueous silicate solution promoted gel formation. Small amounts of Al(3+) ions were incorporated as a four-coordinated complex at early stage of polymerization reaction of silicates and during subsequent reaction six-coordinated Al complex increased, suggesting reversible conversion between 4- and 6-coordinated complexes. SO4(2-) ions interact with positive surfaces of aluminosilicates and are specifically adsorbed on the surface sites of 6-coordinated Al(3+) species, which may be stabilized on silicate surfaces as [Al(H2O)5SO4](+).

Comparison study of phosphorus adsorption on different waste solids: Fly ash, red mud and ferric–alum water treatment residues

The adsorption of phosphorus (P) onto three industrial solid wastes (fly ash, red mud and ferric–alum water treatment residual (FAR)) and their modified materials was studied systematically via batch experiments. Compared with two natural adsorbents (zeolite and diatomite), three solid wastes possessed a higher adsorption capacity for P because of the higher Fe, Al and Ca contents. After modification (i.e., the fly ash and red mud modified by FeCl3 and FARs modified by HCl), the adsorption capacity increased, especially for the modified red mud, where more Fe bonded P was observed. The P adsorption kinetics can be satisfactorily fitted using the pseudo-second-order model. The Langmuir model can describe well the P adsorption on all of the samples in our study. pH and dissolved organic matter (DOM) are two important factors for P adsorption. Under neutral conditions, the maximum adsorption amount on the modified materials was observed. With the deviation from pH7, the adsorption amount decreased, which resulted from the change of P species in water and surface charges of the adsorbents. The DOM in water can promote P adsorption, which may be due to the promotion effects of humic-Fe(Al) complexes and the pH buffer function exceeds the depression of competitive adsorption.

Microstructure and Mechanical Properties of AA1050/AA6061/AA1050 Complex Sheet Fabricated by Roll Bonding Process

A cold roll-bonding process was applied to fabricate an AA1050/AA6061/AA1050 laminate complex sheet. Two AA1050 and one AA6061 sheets of 2 mm thickness, 40 mm width and 300 mm length were stacked up after surface treatment that included degreasing and wire brushing; material was then reduced to a thickness of 3 mm by one-pass cold rolling. The laminate sheet bonded by the rolling was further reduced to 1.2 mm in thickness by conventional rolling. The rolling was performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 210 mm. The rolling speed was 5.0 m/sec. The AA1050/AA6061/AA1050 laminate complex sheet fabricated by roll bonding was then hardened by natural aging T4) and artificial aging (T6) treatments. The microstructures of the as-roll bonded and the age hardened Al complex sheets were revealed by optical microscope observation; the mechanical properties were investigated by tensile testing and hardness testing. The strength of the as-roll bonded complex sheet was found to increase by 2.9 times compared to that value of the starting material. In addition, the hardness of the complex sheets increased with cold rolling for AA1050 and age-hardening treatment for AA6061, respectively. After heat treatment, both AA1050 and AA6061 showed typical recrystallization structures in which the grains were equiaxed; however, the grain size was smaller in AA6061 than in AA1050.

Dispersive ionic liquid microextraction of aluminium from environmental water samples by effervescent generation of carbon dioxide

ABSTRACTA green effervescent in-situ generation of CO2-tablet-induced dispersive ionic liquid microextraction (DILME) method has been first time used for the preconcentration and determination of trace levels of aluminium [Al(III)] in real water samples by graphite furnace atomic absorption spectrometry (GFAAS). In the present approach, 1-methyl-3-octylimidazolium hexafluorophosphate [OMIM][PF6] was dispersed in an aqueous medium by the effervescent reaction of CO2-tablet to increase phase transfer ratio, which significantly improve the extraction recovery of Al(III) complex with 1-(2-pyridylazo)-2-naphthol, into extraction solvent. Limit of detection and enrichment factor were found to be 0.045 µg L−1 and 42.4, respectively. Validation of the developed method was carried out to determined Al(III) in a certified reference material (SLRS-4 riverine water) and the results were found to be in good agreement with the certified value. The relative standard deviation was found to be 4.3%. The developed method was applied to different water samples.

A Challenge for Rechargeable Al-Batteries: AlCl3-Free Deep Eutectic Solvent and Cationic Solvate Based Electrolytes

: The rapidly growing demands for electric power sources, especially in the electromobility field, but increasing in importance also for large-scale stationary energy storage applications for renewable energy, requires novel highly efficient electrochemical energy storage systems. Post Li-ion batteries are a collection of various promising battery technologies. While some strategies focus on enabling the use of Li metal anodes, such as Li-sulfur and Li-air batteries, others turn away from Li altogether and focuses on multivalent metal based batteries, e.g. Mg,1 Ca,2 and Al.3 Among these, a rechargeable Al-battery would offer the largest volumetric capacity of the negative electrode due to its relatively high density combined with the three electron transfer possible by Al3+. Safety issues, however, have hampered a materialization of any practical Al-battery, as almost all non-aqueous Al-conducting electrolytes and batteries incorporate the extremely reactive AlCl3. One of the most straightforward approaches to address this issue is by developing AlCl3-free electrolytes that enable an Al-battery. We have prepared hundreds of various traditional salt and solvent based non-aqueous Al electrolytes, but unfortunately no electrochemical activity has been found, possibly due to poor Al salt dissociation and severe side-reactions. Therefore alternative approaches based on different concepts are urged for; two possible candidates are deep eutectic solvents (DESs) and cationic solvates. DESs are fluids composed of mutually miscible components, often metal salts and various solid/liquid organic compounds, which form eutectics by an entropic effect. The recent successes of reversible electro-plating/stripping of multivalent metals from metal complexes with cationic active species,4–6 have inspired us to also investigate similar aluminum cationic solvates. For the DES based electrolytes, we propose a series of ternary electrolytes consisting of aluminum trifluoromethanesulfonate (Al[TfO]3), N-methylacetamide (NMA), and urea. The replacement of AlCl3 by Al[TfO]3 can address the safety issues of AlCl3. By selecting appropriate compositions, the Al[TfO]3 salt is highly dissociated and the Al conduction mechanism decoupled from viscosity limitations, and consequently these ternary electrolytes can provide excellent ionic conductivities even at room temperature (Figure 1).7 While the reversible electrochemical properties of the optimized ternary electrolyte, Al[TfO]3/NMA/urea = 0.05/0.76/0.19, opens for conceptual new possibilities to design electrolytes, these were however modest compared to conventional AlCl3-based electrolytes. For the cationic solvate based approach, we have successfully synthesized alkylhaloaluminate-free cationic Al complexes with very varying ligand and anion structures,8,9 and the structures and electrochemical properties of these will be discussed. Acknowledgement: The financial support by Chalmers Area of Advance Materials Science and the Swedish Energy Agency programme “Batterifonden” is gratefully acknowledged. The authors are also thankful for the continuous support by Chalmers Areas of Advance Energy and Transport.

Synthesis, Characterization and Preliminary Microbial Studies of 4-{[(E)–1h–Indol–3h–Lmethylidene]Amino}–1,5-Dimethyl-2-Phenyl-1,2-Dihydro-3h-Pyrazol–3-One and Its Al(Iii), In(Iii) and Tl(I) Complexes

4-{[(E)–1H–indol–3H–ylmethylidene]amino}–1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol–3-one and its Al(III), In(III) and Tl(I) Complexes have been synthesized and characterized by physical methods and spectral studies. All the complexes were purified and their structures were elucidated using melting point, stoichiometry, molar conductivity, UV-visible, infrared, nuclear magnetic resonance and GCMS Spectral Studies The geometry around the metals were deduced based on the spectral information and were found to be five coordinate in all the complexes. The Schiff base ligand is coordinated to the metals through the participation of its imine nitrogen, indole-nitrogen and the oxygen of the antipyrine moiety. These complexes were also tested against different bacteria and fungi using Agar well diffusion method to determine their antimicrobial potency and they were found sensitive against Escherichia Coli, Pseudomonas aeruginosa, Basillus subtilis and Candida albicans but none was found active against Staphylococcus aureus.

Catalytic Coupling of Carbon Dioxide with Terpene Scaffolds: Access to Challenging Bio-Based Organic Carbonates.

The challenging coupling of highly substituted terpene oxides and carbon dioxide into bio-based cyclic organic carbonates catalyzed by Al(aminotriphenolate) complexes is reported. Both acyclic as well as cyclic terpene oxides were used as coupling partners, showing distinct reactivity/selectivity behavior. Whereas cyclic terpene oxides showed excellent chemoselectivity towards the organic carbonate product, acyclic substrates exhibited poorer selectivities owing to concomitant epoxide rearrangement reactions and the formation of undesired oligo/polyether side products. Considering the challenging nature of these coupling reactions, the isolated yields of the targeted bio-carbonates are reasonable and in most cases in the range 50-60 %. The first crystal structures of tri-substituted terpene based cyclic carbonates are reported and their stereoconnectivity suggests that their formation proceeds through a double inversion pathway.

Completing the Heterocubane Family [Cp*AlE]4 (E = O, S, Se, and Te) by Selective Oxygenation and Sulfuration of [Cp*Al]4: Density Functional Theory Calculations of [Cp*AlE]4 and Reactivity of [Cp*AlO]4 toward Hydrolysis.

The subvalent aluminum compound [Cp*Al]4 (1) reacts with dioxygen, N2O, or sulfur to yield the heterocubane complexes [Cp*AlX]4 [X = O (2) and S (3)]. Treatment of [Cp*AlO]4 (2) with (tBuO)3SiOH gave [(tBuO)3SiOAlO]4 (6) and Cp*H. The structures and spectroscopic data of the Al clusters are supported by density functional theory (DFT) calculations, which also demonstrate the importance of noncovalent interactions (NCI) in oligomeric Al(I) complexes as well as in [Cp*AlS]4 and the heavier homologues of Se and Te. The computed (27)Al NMR shifts indicate a deshielding at the Al centers with increasing electronegativity of the chalcogen atom as well as significant spin-orbit shielding effects within the heavier heterocubane [Al4E4] cores. Further hydrolysis of 6 with an additional amount of silanol in the presence of water resulted in the formation of [Al4(OH)6(OH2)2(OSiOtBu3)6] (7), which shows a structural motif found in boehmite and diaspore.

Aluminum complex initiated copolymerization of lactones and DL‐lactide to form crystalline gradient block copolymers containing stereoblock lactyl chains

ABSTRACTThe homopolymerization reactions of several lactones, as well as the copolymerization reactions of DL‐lactide with these lactones were investigated using tridentate Schiff base aluminum complexes as the initiators. ε‐Caprolactone and δ‐valerolactone polymerized efficiently at room temperature to afford polyesters, whereas β‐butyrolactone only gave the corresponding oligomer. The copolymerization reactions of DL‐lactide with caprolactone and valerolactone yielded gradient block copolymers where the lactyl blocks formed crystalline stereoblocks as a consequence of the stereoselective polymerization of DL‐lactide in the presence of the aluminum complexes. These polymerization processes were highly controlled in nature, and block copolymerization where caprolactone copolymerized using poly(DL‐lactide)‐Al complex proceeded. The obtained gradient copolymer containing stereoblock lactyl blocks and caproyl blocks were analyzed using WAXD analysis to uncover existence of the crystalline stereoblock lactyl blocks in the copolymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2016,54, 2536–2544

Polyphenol-Aluminum Complex Formation: Implications for Aluminum Tolerance in Plants.

Natural polyphenols may play an important role in aluminum detoxification in some plants. We examined the interaction between Al(3+) and the purified high molecular weight polyphenols pentagalloyl glucose (940 Da) and oenothein B (1568 Da), and the related compound methyl gallate (184 Da) at pH 4 and 6. We used spectrophotometric titration and chemometric modeling to determine stability constants and stoichiometries for the aluminum-phenol (AlL) complexes. The structures and spectral features of aluminum-methyl gallate complexes were evaluated with quantum chemical calculations. The high molecular weight polyphenols formed Al3L2 complexes with conditional stability constants (β) ∼ 1 × 10(23) at pH 6 and AlL complexes with β ∼ 1 × 10(5) at pH 4. Methyl gallate formed AlL complexes with β = 1 × 10(6) at pH 6 but did not complex aluminum at pH 4. At intermediate metal-to-polyphenol ratios, high molecular weight polyphenols formed insoluble Al complexes but methyl gallate complexes were soluble. The high molecular weight polyphenols have high affinities and solubility features that are favorable for a role in aluminum detoxification in the environment.