Tetradentate N2O2 Schiff Base Ligand Research Articles

Photo‐induced organo‐manganese‐mediated radical polymerization of acrylates under LED irradiation

The role of manganese in photo‐induced organometallic‐mediated radical polymerization (photo‐OMRP) under LED (light‐emitting diode) irradiation has not been previously explored. In this study, four manganese (II) complexes, namely [Mn(6‐tert‐butyl‐N,N′‐propanebis [salicylimine])] (Mn‐Bu), [Mn(6,3‐di‐tert‐butyl‐N,N′‐propanebis [salicylimine])] (Mn‐Bu2), [Mn(6‐ethoxy‐N,N′‐propanebis [salicylimine])] (Mn‐Ethoxy), and [Mn(6,3‐di‐ethoxy‐N,N′‐propanebis [salicylimine])] (Mn‐Ethoxy2), were synthesized using both symmetrical and non‐symmetrical tetradentate N2O2 Schiff base ligands. The Schiff base ligands were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), and nuclear magnetic resonance spectroscopy (NMR). The Mn (II) complexes were characterized by FTIR, UV–Vis, elemental analysis, molar conductivity, cyclic voltammetry, MALDI‐TOF mass spectrometry, electron paramagnetic resonance, and rationalized with density functional theory (DFT) studies. All complexes were evaluated as photo‐OMRP mediators under LED irradiation at 390 nm and in the 400–800 nm range. The photopolymerization utilized methyl acrylate (MA) and diphenyl(2,4,6‐trimethylbenzoyl)phosphine oxide (TPO) in varying molar ratios of [MA]/[MnII]/[TPO] (900/1/1, 600/1/1, and 600/1/0.5). The photo‐OMRP of MA mediated by Mn‐Bu2 showed the best control over molecular weight (Mn matching Mn,th) and dispersity (Ð < 1.30) at a [MA]/[MnII]/[TPO] = 600/1/0.5 M ratio. The polymerization system demonstrated a living character, as evidenced by reversible “on/off” light source switching. Furthermore, a block copolymer of poly (methyl acrylate)‐b‐poly (butyl acrylate) was successfully synthesized employing a sequential visible‐light‐induced process, with the Mn‐Bu2 system showing the best results.

Structural characterisation of novel mononuclear Schiff base metal complexes, DFT calculations, molecular docking studies, free radical scavenging, DNA binding evaluation and cytotoxic activity

New mononuclear metal complexes (M = Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II)) derived from a novel tetradentate N2O2 Schiff base ligand (H2L) were efficiently produced. Physico‐chemical and spectroscopic approaches were used to characterize the synthesized metal complexes. The data indicated that the synthesized Schiff base acted as a tetradentate ligand and linked to various metal ions through the imine group's nitrogen and the phenolate oxygen. The capability of the produced complexes to bind CT‐DNA using absorbance, fluorescence, viscosity and thermal denaturation assays along with DPPH radical scavenging was evaluated. The results revealed that both Mn(II) and Cu(II) complexes have a higher binding affinity and antioxidant activity when compared with other complexes. In vitro anti‐proliferative activity of the new complexes using MTT assay was also performed against tumor cell lines HepG‐2 and MCF‐7. The results showed good activity on comparing with the reference medication cisplatin. Molecular geometry of metal complexes was examined using density functional theory (DFT) simulations. In addition, the DNA‐interaction studies of complexes were validated by molecular docking experiments using molecular operating environment (MOE) software.

Metal–ligand binding energies in copper (II) and nickel (II) complexes with tetradentate N2O2 Schiff base ligands

This work constitutes a new contribution for understanding the relationship between the metal–ligand bonding and, indirectly, the inherent reactivity of metallic complexes with tetradentate N2O2 Schiff base ligands, being reported the energetic characterization of two transition metal complexes – (N,N'́-bis(salicylaldehydo)tetramethylenediiminate)nickel(II) and (N,N'-bis(salicylaldehydo)propylenediiminate)copper(II). The standard molar enthalpies of formation of these complexes were determined by solution-reaction calorimetry measurements. Their standard molar enthalpies of sublimation, at T = 298.15 K, were obtained by an effusion method. From these studies, the gas-phase enthalpies of formation of Ni(II) and Cu(II) complexes, at T = 298.15 K, were derived. Differences between the metal–ligand and mean hydrogen-ligand bond dissociation enthalpies were derived and discussed in structural terms, in comparison with identical parameters for complexes of the same metals with analogous tetradentate Schiff bases. High-level quantum chemical calculations have also been conducted, complementing the results obtained experimentally.

Synthesis, characterization, antimicrobial, BSA binding, DFT calculation, molecular docking and cytotoxicity of Ni(II) complexes with Schiff base ligands

A series of a tetradentate N2O2 Schiff base ligands (1a-e), [N,N′-(X)bis(salicylidene)1,2-phenylenediamine], salphens {where X = H (1a), Cl (1b), Br (1c), CH3 (1d), OCH3(1e)} were synthesized from condensation of substituted salicylaldehydes with 1,2-phenylenediamine and nickel(II) complexes(2a-e) from corresponding Schiff base ligands(1a-e). The stoichiometric ratios of the prepared ligands (1a-e) and their Ni(II)-salphen complexes (2a-e) were structurally characterized by various analytical and spectroscopic techniques such as 1H NMR, FT-IR, mass, UV‐–visible, PXRD, magnetic moments and molar conductivity measurements. These results suggest that Ni(II)-salphen complexes (2a-e) have square planar geometry. The molar conductivity measurements indicate that all complexes (2a-e) are non-electrolytes. Density Functional Theory (DFT) calculations have been used to investigate the optimized structure and chemical reactivity of these Ni(II) complexes(2a-e) from their Frontier Molecular Orbitals (FMO). The binding capabilities of the Ni(II) Schiff base complexes (2a-e) with Bovine Serum Albumin (BSA) have been studied through electronic absorption, fluorescence and cyclic voltammetric methods. Further the nature of interaction of Ni(II) complexes (2a-e) towards BSA were confirmed using molecular docking analyses. All these results demonstrated that the Ni(II) complexes 2d and 2e have better binding affinity towards BSA among all the Ni(II) complexes. The antimicrobial studies reveal that the Ni(II)-salphen complexes (2a-e) have higher inhibitory effect than ligands (1a-e) against the selected pathogenic microorganisms. Furthermore, in vitro cytotoxicity of ligands (1a-e) and Ni(II) complexes(2a-e) were evaluated by MTT assay against MCF-7. The observed IC50 values against MCF-7 cell lines suggest that Ni(II) complexes(2a-e) show more significant anticancer activity than their corresponding ligands(1a-e). It is explored that complexes 2d and 2e bearing electron donating groups have greater anticancer potency. Comparison of our results with cisplatin, Zn(II)-salphen and V(IV)-salphen complexes indicated that Ni(II)-salphen complexes can be considered as the potential candidates for use as effective anticancer agent in future.

Thermal Studies of Iron (II) Schiff Base Complexes: New Precursors for Preparation of α-Fe2O3 Nanoparticles via Solid-State Thermal Decomposition

In this research study, four iron (II) complexes of tetradentate N2O2 Schiff base ligands with the general formula of Fe((MeO-bph)2 Am) (Am=1,2-ethyelenediamine (1), 1,3-propanediamine (2), 1,4-buanediamine (3) and 2,2-dimethyl-1,3-propanediamine (4) were synthesized and characterized using the elemental analysis (CHN) and FT-IR spectroscopy. Thermal properties and decomposition stages of all the complexes were evaluated. Finally, all complexes were decomposed at 600 °C for 3 h and the dark precipitates were characterized using the FT-IR, XRD and SEM. FT-IR and XRD results revealed that the precipitate were the pure phase of rhombohedral of magnetite (α-Fe2O3) nanoparticles. The SEM images showed that, the morphology of the precipitate was a relatively spherical shape and average diameter of 40-70 nm. The results of the thermogravimetric analysis the iron (II) complexes showed that the complexes 1–4 were stable until 140-200 °C. However, after that, all the complexes 1–4 decomposed in two stages at various temperatures.

Synthesis, crystal structure, and characterization of two Cu(II) and Ni(II) complexes of a tetradentate N2O2 Schiff base ligand and their application in fabrication of a hydrazine electrochemical sensor

Two new Cu(II) and Ni(II) complexes of a tetradentate N2O2 Schiff base ligand (H2L = N,N'-bis-(4-hydroxysalicylidene)-ethylenediamine) were synthesized. The structures of the H2L ligand and its complexes (1 and 2) were unambiguously determined by elemental analysis, FT-IR, 1H NMR, and UV–Vis spectroscopy. The crystal structures of the complexes were also determined by X-ray crystallography technique. In addition, the complexes were tested as a modifier for a glassy carbon electrode (GCE) to prepare an electrochemical sensor for detection of hydrazine in real samples. The prepared sensor with Ni(II) complex showed admirable sensitivity and selectivity for determination of hydrazine at 0.55 V without any interference of other common substrates. A dynamic linear range of 0.5–150 µM with a detection limit (LOD) of 166.66 nM and sensitivity of 0.1174 μA µM−1 cm−2 was achieved. The obtained LOD was much lower than that specified in the U.S. Environmental Protection Agency (EPA) regulations. The prepared sensor was also successfully applied to detect hydrazine in Tehran’s Jajrood river water as a real sample.

Dinuclear Zn(II) and tetranuclear Co(II) complexes of a tetradentate N2O2 Schiff base ligand: Synthesis, crystal structure, characterization, DFT studies, cytotoxicity evaluation, and catalytic activity toward benzyl alcohol oxidation

Two novel dinuclear Zn(II) and tetranuclear Co(II) complexes of a tetradentate N2O2 Schiff base ligand (H2L = N,N′‐bis‐(4‐hydroxysalicylidene)‐1,3‐diaminopropane) were prepared. The structures of the H2L ligand, [4(Zn2L(μ‐O2CCH3)(O2CCH3)(H2O))]⋅4CH3OH⋅3H2O (complex 1) and [Co4L2(μ‐O2CCH3)2(O2CCH3)2]⋅2H2O (complex 2) were unambiguously characterized by elemental analysis, mass spectrometry, Fourier‐transform infrared spectroscopy (FT‐IR), 1H nuclear magnetic resonance (NMR), and UV–Vis spectroscopy. Single crystal X‐ray diffraction studies revealed that two Zn(II) nuclei of 1 were connected through μ‐phenolato and μ‐acetato bridges and had distorted square pyramidal and distorted octahedral coordination geometries. Four Co(II) nuclei of 2, on the contrary, showed a Co4O4 cubane‐like configuration in which Co(II) cations and O atoms were located at alternating corners of a distorted cube. Density functional theory studies at the B3LYP/6–31 G(d) level were carried out to gain an insight into the thermodynamic stability of the complexes. in vitro cytotoxicity of the ligand and the complexes were evaluated using the MTT assay against breast cancer MCF7 cells, melanoma cancer A375 cells, and prostate cancer PC3 cells as representative human cancer cell lines. Complex 1 showed a remarkable activity against A375 and PC3 cancer cell lines. In addition, 1 and 2 were used as precursors to produce zinc and cobalt oxide nanoparticles via pyrolysis technique. The resulting ZnO and Co3O4 nanoparticles were characterized using FT‐IR spectroscopy, UV–Vis diffuse reflectance spectroscopy, powder X‐ray diffraction, and field emission scanning electron microscopy. Then, these nanoparticles were used as heterogeneous catalysts in the oxidation of benzyl alcohol with hydrogen peroxide at room temperature. Both catalysts showed good recyclability with a negligible decrease in their efficiency during four catalytic cycles. The results of theoretical calculations showed that the most stable product was benzaldehyde, which is in good agreement with the obtained experimental results.

Stöber synthesis of salen-formaldehyde resin polymer- and carbon spheres with high nitrogen content and application of the corresponding Mn-containing carbon spheres as efficient electrocatalysts for the oxygen reduction reaction.

Salen-formaldehyde (SF) resin polymer spheres were synthesized by the Stöber method from 4,4′-dihydroxysalen (N,N′-bis-(4-hydroxysalicylidene)-ethylenediamine; a tetradentate N2O2 Schiff base ligand) and formaldehyde. The salen precursor was prepared by condensation of ethylenediamine with 2,4-dihydroxybenzaldehyde in methanol. The SF resin colloidal spheres were also prepared by using Pluronic F127 and ammonia as a porogenic agent and catalyst, respectively (SF-P). In addition, corresponding Mn(ii)-coordinated polymer spheres of the SF-P were synthesized (SF-P-Mn(ii)). Corresponding monodispersed carbon spheres of all of the abovementioned samples were also obtained by pyrolysis technique. All of the products were characterized with conventional microscopic and spectroscopic techniques, as well as other physical methods such as BET analysis. It was found that carbonization of the SF resin spheres results in carbon spheres with specific surface areas in the range of 499–528 m2 g−1 and average pore sizes in the range of 2.58–3.08 nm. Nitrogen content of the SF-MWHT (obtained hydrothermally in a methanol/water mixture), and SF-P-C@Mn (obtained from carbonization of SF-P-Mn(ii)) samples were as high as 27.5 wt% and 35.02 wt%, respectively. Finally, a glassy carbon electrode (GCE) modified with SF-P-C@Mn (SF-P-C@Mn/GCE) was prepared and its electrocatalytic activity was evaluated for oxygen reduction reaction (ORR) by linear sweep voltammetry (LSV). The LSV results showed that the SF-P-C@Mn/GCE has a higher current density and a lower negative potential in the ORR compared to GCE.

Solid-State Nonlinear Optical Properties of Mononuclear Copper(II) Complexes with Chiral Tridentate and Tetradentate Schiff Base Ligands.

Salen-type metal complexes have been actively studied for their nonlinear optical (NLO) properties, and push-pull compounds with charge asymmetry generated by electron releasing and withdrawing groups have shown promising results. As a continuation of our research in this field and aiming at solid-state features, herein we report on the synthesis of mononuclear copper(II) derivatives bearing either tridentate N2O Schiff bases L(a−c)− and pyridine as the forth ancillary ligand, [Cu(La−c)(py)](ClO4) (1a–c), or unsymmetrically-substituted push-pull tetradentate N2O2 Schiff base ligands, [Cu(5-A-5′-D-saldpen/chxn)] (2a–c), both derived from 5-substituted salicylaldehydes (sal) and the diamines (1R,2R)-1,2-diphenylethanediamine (dpen) and (1S,2S)-1,2-diaminocyclohexane (chxn). All compounds were characterized through elemental analysis, infrared and UV/visible spectroscopies, and mass spectrometry in order to guarantee their purity and assess their charge transfer properties. The structures of 1a–c were determined via single-crystal X-ray diffraction studies. The geometries of cations of 1a–c and of molecules 2a–c were optimized through DFT calculations. The solid-state NLO behavior was measured by the Kurtz–Perry powder technique @1.907 µm. All chiral derivatives possess non-zero quadratic electric susceptibility (χ(2)) and an efficiency of about 0.15–0.45 times that of standard urea.

Synthesis, crystal structure, experimental and theoretical studies of tetradentate N2O2 Schiff base ligand and its Ni(II) and Pd(II) complexes

The synthesis of a novel ligand bis(3-methoxysalicylidene)-4-methylbenzene-1,2-diamine (H2L) has been carried out by the condensation of 4-methylbenzene-1,2-diamine with 3-methoxysalicylaldehyde. The Ni(II) and Pd(II) Schiff base complexes have been synthesized from the reaction of Ni(OAc)2·4H2O and Pd(OAc)2 with the Schiff base ligand (H2L) in methanol and acetonitrile, respectively. The ligand and its complexes have been characterized by elemental analyses, FT-IR, 1H-NMR and UV–Vis spectroscopy. Moreover, the crystal structure of the ligand has been determined by single crystal X-ray crystallography. To have better understanding of electronic transitions of the ligand and its complexes, density functional theory (DFT) calculations have been performed. The geometries and electronic properties of the compounds have been obtained with the M062X level at Def2-TZVP basis set. Additionally, NBO analysis has been performed to interpret electronic transitions by determining their included occupied and virtual orbitals. The theoretical parameters confirmed the suggested structure of complexes. The spectroscopic data obtained from DFT calculations show acceptable agreement with the experimental results.

Nickel(II) and Copper(II) Complexes of a New Tetradentate Schiff Base Ligand: Synthesis, Characterization, Thermal Studies and Use as Precursors for Preparation of NiO and CuO Nanoparticles

A new tetradentate N2O2 Schiff base ligand (MeO-bph)2bn = N,N¢-bis(2-hydroxy-4-methoxybenzophenone)-1,4-butanediamine was prepared from the condensation of butane-1,4-diamine with 4-methoxy-2-hydroxybenzophenone and characterized by 1H-NMR spectroscopy and single-crystal X-ray diffraction. Its nickel(II) and copper(II) complexes characterized using elemental analyses (CHN) and IR spectroscopy. Thermogravimetric analysis of the Schiff base ligand and its Ni(II) and Cu(II) complexes revealed their thermal stability and decomposition pattern. Finally, the complexes were used for the preparation of NiO and CuO nanoparticles by solid-state thermal decomposition. The nanoparticles were characterized by FT-IR, XRD, and SEM. FT-IR and XRD confirmed the purity of the formed products NiO and CuO.

Multielectron redox processes in polymeric cobalt complexes with N2O2 Schiff base ligands

A series of polymeric cobalt (II) complexes with tetradentate N2O2 Schiff base ligands (poly-[Co(Schiff)]) are prepared via oxidative electrochemical polymerization and characterized by scanning electron microscopy, cyclic voltammetry, quartz crystal microgravimetry, and in situ UV/Vis spectroscopy in inert atmosphere. Integration of data from all techniques revealed that (a) all studied poly-[Co(Schiff)] films demonstrate multi-electron redox switching between 0 V and +1.4 V (vs. Ag/AgCl); (b) the Co(II) to Co(III) conversion takes place in the early stage of polymer oxidation, which is followed by both one- and two-electron ligand-based redox processes in the later stages; (c) the number of electrons exchanged by each monomer unit during oxidation/reduction of the polymer depends on the substituents in the imine bridge and aldehyde moieties of the ligand, as well as on the donor number of the electrolyte solvent. The poly-[Co(CH3O-SaltmEn)] film demonstrates the ability to be reversibly oxidized by three electrons per a monomer unit in an acetonitrile-based electrolyte, which makes it a viable candidate for energy storage applications.

Anchoring of Copper(II) Schiff Base Complex into Aminopropyl-Functionalised MCM-41: A Novel, Efficient and Reusable Catalyst for Selective Oxidation of Alcohols

A copper(II) complex containing tetradentate N2O2 Schiff base ligand immobilized into aminopropyl-functionalised MCM-41 (mobile crystalline material number 41), was prepared and characterized by Fourier-transform infrared, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, N2 adsorption–desorption and inductively coupled plasma analysis techniques. The novel heterogeneous catalyst, MCM-41-pr-NH2-CuL, can be successfully applied for efficient and selective oxidation of different primary and secondary alcohols to the corresponding carbonyl compounds using hydrogen peroxide as an oxidant in acetonitrile at 60 °C. The effect of reaction parameters such as solvent, amount of catalyst, temperature and kind of oxidant on the oxidation of benzyl alcohol was also studied. The prepared catalyst could be recovered and reused four times without important loss of its catalytic performance. The heterogeneous MCM-41-pr-NH2-CuL catalyst was found to be catalytically more active in the oxidation of alcohols compared to the similar type of copper(II) Schiff base complex in homogeneous media under the same reaction conditions.

Epoxidation of alkenes by an oxidovanadium(IV) tetradentate Schiff base complex as an efficient catalyst with tert-butyl hydroperoxide

A new asymmetrical tetradentate N2O2 Schiff base ligand was synthesized from 2-hydroxyacetophenon, 2-hydroxynaphthaldehyde and 1,2 phenylenediimine. The new oxidovanadium(IV) Schiff base complex, VIVOL (L=N-2-hydroxyacetophenon-N′-2-hydroxynaphthaldehyde-1,2 phenylenediimine), was prepared by reaction of Schiff base ligand with vanadyl acetylacetonate. The Schiff base ligand (L) and the oxidovanadium(IV) complex were characterized by spectroscopic methods. The crystal structure of the complex was determined by the single crystal X-ray analysis. The complex crystallized in the orthorhombic system, having one V4+ ion coordinating in an approximately square pyramidal N2O3 geometry by two azomethine N atoms and phenolic oxygens from Schiff base ligand in a square plane and one oxygen atom in an apical position. Electrochemical properties of the complex were examined by means of cyclic voltammetry. The catalytic activity of the oxidovanadium(IV) Schiff base complex was tested in the epoxidation of cyclooctene.

A novel trinuclear copper(II) complex containing a symmetric tetradentate N2O2 Schiff base ligand: Synthesis, characterization, crystal structure and its usage as a new precursor for the preparation of CuO particles

A novel linear centrosymmetric trinuclear copper(II) Schiff base complex with the chemical formula [{Cu(μ-L)(H2O)(μ-NO3)}2Cu]·H2O, where L=N,N′-bis(2-hydroxy-4-methoxybenzophenone)-2,2-dimethyl-1,3-propanediamine, was synthesized and characterized by elemental analyses, FT-IR spectroscopy, TG-TA and X-ray crystallography. Single X-ray diffraction analysis revealed four μ-phenoxido- and two μ-NO3− bridges in the complex. The equatorial plane of the three linearly arranged copper(II) atoms is formed by oxygen and nitrogen atoms of two anionic tetradentate Schiff base ligands, each of them coordinated to one of the terminal copper(II) ions. The central copper(II) ion is located in an inversion centre and bonded to four μ-oxygen atoms of the same ligand. Thermogravimetric analysis of the complex revealed its thermal stability and decomposition pattern. Finally, the complex was used for the preparation of CuO particles by solid state thermal decomposition.

New Zn(II) and Cu(II) complexes with in situ generated N2O2 siloxane Schiff base ligands

Two novel mononuclear zinc(II) and copper(II) complexes of tetradentate N2O2 Schiff base ligands generated in situ by the template method were synthesized by the reaction of salicylicaldehyde and o-vanillin, respectively, with 1,3-bis(3-aminopropyl)tetramethyldisiloxane and the corresponding metal salts, in the presence of pyridine. The structures of the metal complexes were determined by elemental and spectral (IR, UV–Vis, ESI-MS) analyses as well as by single crystal X-ray diffraction, revealing a tetrahedral coordination geometry around the copper and zinc atoms ensured by the N2O2 donors of the Schiff bases. The crystalline structures are stabilized by intermolecular π–π stacking and short C–H⋯π interactions, which generate supramolecular polymeric chains. The absorption and emission properties of the complexes were studied in solution. The antimicrobial activity was assayed in vitro against three fungi and two bacteria species. Both complexes are moisture stable, as was proved by vapor sorption (DVS) analysis. The catalytic activity of the complexes was evaluated in the decomposition reaction of hydrogen peroxide.

A gallium(III) Schiff base-curcumin complex that binds to amyloid-β plaques

Gallium-68 is a positron-emitting isotope that can be used in positron-emission tomography imaging agents. Alzheimer's disease is associated with the formation of plaques in the brain primarily comprised of aggregates of a 42 amino acid protein called amyloid-β. With the goal of synthesising charge neutral, low molecular weight, lipophilic gallium complexes with the potential to cross the blood–brain barrier and bind to Aβ plaques we have used an ancillary tetradentate N2O2 Schiff base ligand and the β-diketone curcumin as a bidentate ligand to give a six-coordinate Ga3+ complex. The tetradentate Schiff base ligand adopts the cis-β configuration with deprotonated curcumin acting as a bidentate ligand. The complex binds to amyloid-β plaques in human brain tissue and it is possible that extension of this chemistry to positron-emitting gallium-68 could provide useful imaging agents for Alzheimer's disease.

Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition

A series of new VO(IV) complexes of tetradentate N2O2 Schiff base ligands (L1–L4), were synthesized and characterized by FT-IR, UV–vis and elemental analysis. The structure of the complex VOL1⋅DMF was also investigated by X-ray crystallography which revealed a vanadyl center with distorted octahedral coordination where the 2-aza and 2-oxo coordinating sites of the ligand were perpendicular to the “-yl” oxygen. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO<H<Br<Cl. We also studied the thermodynamics of formation of the complexes and kinetic aspects of their thermal decomposition. The formation constants with various substituents on the aldehyde ring follow the trend 5-OMe>5-H>5-Br>5-Cl. Furthermore, the kinetic parameters of thermal decomposition were calculated by using the Coats–Redfern equation. According to the Coats–Redfern plots the kinetics of thermal decomposition of studied complexes is of the first-order in all stages, the free energy of activation for each following stage is larger than the previous one and the complexes have good thermal stability. The preparation of VOL1⋅DMF yielded also another compound, one kind of vanadium oxide [VO]X, with different habitus of crystals, (platelet instead of prisma) and without L1 ligand, consisting of a V10O28 cage, diaminium moiety and dimethylamonium as a counter ions. Because its crystal structure was also new, we reported it along with the targeted complex.

Correction: Zeolite encapsulated Ni(ii) and Cu(ii) complexes with tetradentate N2O2Schiff base ligand: catalytic activity towards oxidation of benzhydrol and degradation of rhodamine-B

Download options Please wait... Associated articles Zeolite encapsulated Ni(ii) and Cu(ii) complexes with tetradentate N2O2 Schiff b… Article information DOI https://doi.org/10.1039/C4TA90172J Article type Correction Submitted 26 Sep 2014 Accepted 26 Sep 2014 First published 13 Oct 2014 This article is Open Access Download Citation J. Mater. Chem. A, 2014,2, 19102-19102 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Correction: Zeolite encapsulated Ni(II) and Cu(II) complexes with tetradentate N2O2 Schiff base ligand: catalytic activity towards oxidation of benzhydrol and degradation of rhodamine-B G. R. Reddy, S. Balasubramanian and K. Chennakesavulu, J. Mater. Chem. A, 2014, 2, 19102 DOI: 10.1039/C4TA90172J This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author G. Ramanjaneya Reddy S. Balasubramanian K. Chennakesavulu

Synthesis, characterization, anticancer activity, thermal and electrochemical studies of some novel uranyl Schiff base complexes

Some tetradentate N2O2 Schiff base ligands, such as N,N′-bis(naphtalidene)-1,2-phenylenediamine, N,N′-bis(naphtalidene)-4-methyl-1,2-phenylenediamine, N,N′-bis(naphtalidene)-4-chloro-1,2-phenylenediamine, N,N′-bis(naphtalidene)-4-nitro-1,2-phenylenediamine, N,N′-bis(naphtalidene)-4-carboxyl-1,2-phenylenediamine, and their uranyl complexes were synthesized and characterized by 1H NMR, IR, UV–Vis spectroscopy, TG (thermogravimetry), and elemental analysis (C.H.N.). Thermogravimetric analysis shows that uranyl complexes have very different thermal stabilities. This method is used also to establish that only one solvent molecule is coordinated to the central uranium ion and this solvent molecule does not coordinate strongly and is removed easier than the tetradentate ligand and also trans oxides. The electrochemical properties of the uranyl complexes were investigated by cyclic voltammetry. Electrochemistry of these complexes showed a quasireversible redox reaction without any successive reactions. Also, the kinetic parameters of thermal decomposition were calculated using Coats–Redfern equation. According to Coats–Redfern plots the kinetics of thermal decomposition of the studied complexes is first-order in all stages. Anticancer activity of the uranyl Schiff base complexes against cancer cell lines (Jurkat) was studied and determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide) assay.