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The synthesis of a tetradentate Schiff-base ligand bis(salicylidene)ethylenediamine from salicylaldehyde and ethylenediamine , are important class of ligands . The results of the C.H.N study revealed the formation of a 1:1 [M:L] ratio. .[Er(Salen)(NO3)2]-, square antiprismatic geometry, is the proposed structure of lanthanide metal complex. 1H-NMR, FT-IR, UV-Visible spectral mesurements, and molar conductance were used to estimate the synthesized Schiff-base ligand and its complex. The stoichiometry of the complex has been found to be 1:1 (Er:Salen) matching with C.H.N. analysis. After deprotonation, spectral studies revealed that the ligand was tetradentately coordinated to the metal ion (N2O2) through azomethine nitrogen and phenolic oxygen. The biological activities of the Schiff base (Salen , H2L) and Er(III) complex against E.coli and Staphylococcus bacteria were examined, Schiff base ligand being less active than Erbium (III) complex.

New Ti(IV), Zr(IV) and Al(III) salen-based complexes of formulae [(L)TiCl 2 ], 2, [(L)ZrCl 2 ], 3, and [(L){Al(CH 2 CH(CH 3 ) 2 ) 2 } 2 ], 4, where L = meso -( R , S )-diphenylethylene-salen, were synthesized in high yields. [(L){Al(CH 2 CH(CH 3 ) 2 ) 2 } 2 ] is a bimetallic complex that results from the reaction of H 2 L with either 1 or 2 equivalent of Al(CH 2 CH(CH 3 ) 2 ) 3 . The solid-state molecular structures of compounds 2 and 4·(C 7 H 8 ) were obtained by single-crystal X-ray diffraction. Crystal data for C 44 H 54 Cl 2 N 2 O 2 Ti, (2a): monoclinic, space group C 2/ c (no. 15), a = 27.384(1) A, b = 12.1436(8) A, c = 28.773(2) A, β = 112.644(2)°, V = 8830.6(9) A 3 , Z = 8, μ(MoKα) = 0.350 mm -1 , Dcalc = 1.146 g/cm 3 , 26647 reflections measured (5.204° ≤ 2Θ ≤ 50.7°), 8072 unique ( R int = 0.0967, R sigma = 0.1241) which were used in all calculations. The final R 1 was 0.0640 (I > 2σ(I)) and wR 2 was 0.1907 (all data). Crystal data for C 62 H 72 Cl 2 N 2 O 2 Ti (2b): monoclinic, space group P 2 1 / c (no. 14), a = 19.606(1) A, b = 12.793(1) A, c = 23.189(2) A, β = 105.710(4)°, V = 5599.0(7) A 3 , Z = 4, μ(MoKα) = 0.291 mm -1 , Dcalc = 1.182 g/cm 3 , 37593 reflections measured (3.65° ≤ 2Θ ≤ 50.928°), 10304 unique ( R int = 0.0866, R sigma = 0.1032) which were used in all calculations. The final R 1 was 0.0593 (I > 2σ(I)) and wR 2 was 0.1501 (all data). Crystal data for C 67 H 97 Al 2 N 2 O 2 (4·(C 7 H 8 )): triclinic, space group P -1 (no. 2), a = 10.0619(9) A, b = 16.612(2) A, c = 21.308(2) A, α = 67.193(5)°, β = 78.157(6)°, γ = 77.576(5)°, V = 3176.8(6) A 3 , Z = 2, μ(MoKα) = 0.088 mm -1 , Dcalc = 1.063 g/cm 3 , 42107 reflections measured (5.382° ≤ 2Θ ≤ 51.624°), 12111 unique ( R int = 0.0624, R sigma = 0.0706) which were used in all calculations. The final R 1 was 0.0568 (I > 2σ(I)) and wR 2 was 0.1611 (all data). The solid-state molecular structure of [(L){Al(CH 2 CH(CH 3 ) 2 ) 2 } 2 ] reveals that both metal centres display a slightly distorted tetrahedral geometry bridged by the salen ligand. Both [(L)TiCl 2 ] and [(L)ZrCl 2 ] complexes display octahedral geometry with trans -chlorido ligands.

We clicked a salen ligand onto a thiol-ethane bridged periodic mesoporous organosilica (Salen-PMO) using a photo-initiated thiol-ene click reaction. This process resulted in a covalently bonded salen ligand on the PMO material. The final BET surface area amounts 511 m 2 /g and the pore size diameter is approximately 5.5 nm. The functionalized PMO material showed an excellent carbon dioxide uptake capacity of 1.29 mmol/g at 273 K and 1 bar. More importantly, by coordinating a MoO 2 2+ complex onto the Salen-PMO material, we obtained a heterogeneous catalyst with a good catalytic performance for the epoxidation of cyclohexene. The catalyst was highly reusable, as no decrease in its activity was observed for at least four runs (99% conversion). Finally, the metal-free Salen-PMO showed an exceptional catalytic performance in the cycloaddition of CO 2 to epoxides. The obtained results clearly demonstrate the versatility of the Salen-PMO material not only as metal-free catalyst but also as a support material to anchor metal complexes for specific catalytic applications. With the same catalytic platform, we were able to firstly create epoxides out of alkenes, and subsequently turn these epoxides into cyclic carbonates, consuming CO 2 .

A cationic covalent organic polymer with bifunctional active site was synthesized, which was treated by N, N'-bis(5-bromomethylsalicylaldehyde)ethylenediamine (salen ligand) and tris(1H-imidazol-1-yl) triazine (TIT) in the presence of aluminum ethoxide. The bifunctional cationic covalent organic polymer was investigated by various characterization technologies including PXRD, FT-IR, XPS, TG, SEM, EDS, N2-adsorption and CO2-adsorption. In this polymer, aluminum acts as lewis acid site and bromine ion acts as nucleophile, cooperatively catalyzing the cycloaddition reaction of CO2 and epoxides. Due to its cooperative effect, a higher catalytic activity was found to exhibit 98.1% conversion of epichlorohydrin under optimized conditions (Initial pressure 1.0 MPa, 0.57 mol% catalyst of COP-Al, 90 °C, reaction time 18 h, in the absence of a co-catalyst). Notably, the heterogeneous catalyst still showed good activity and stability after five cycles. A salen-based cationic covalent organic polymers (COP-Al) was used as a bifunctional catalyst for the cycloaddition reaction of CO2 and epoxides with high activity under solvent-free and co-catalyst-free conditions.

Oxidation of nickel salen complexes results in highly reactive species, undergoing polymerisation within microseconds. As a result, oxidation chemistry of NiSalens is available only for sterically hindered complexes. In the present work, an unexpectedly high stability of a nickel complex with a thiophene-based salen ligand was reported and studied. Based on the electrochemical and spectroscopic studies supported by quantum chemical calculations, a rationale for the stability of oxidized nickel complexes with thiophene-based salen ligands was proposed. The introduction of the thiophene core leads to a depletion of spin density on peripheral carbon atoms of the oxidized complex, which switches off its intermolecular reactivity. Instead of this, the initial ligand-centered radical cation undergoes an intramolecular process, namely intervalence tautomerisation, which leads to a highly stable metal-centered oxidized state.

The nature and structure of occupied and empty valence electronic states (molecular orbitals, MOs) of the [Ni(Salen)] molecular complex (NiO2N2C16H14) have been studied by X-ray photoemission and absorption spectroscopy combined with density functional theory (DFT) calculations. As a result, the composition of the high-lying occupied and low-lying unoccupied electronic states has been identified. In particular, the highest occupied molecular orbital (HOMO) of the complex is found to be predominantly located on the phenyl rings of the salen ligand, while the states associated with the occupied Ni 3d-derived molecular orbitals (MOs) are at higher binding energies. The lowest unoccupied molecular orbital (LUMO) is also located on the salen ligand and is formed by the 2pπ orbitals of carbon atoms in phenyl groups of the salen macrocycle. The unoccupied MOs above the LUMO reflect σ- and π-bonding between Ni and its nearest neighbours. All valence states have highly mixed character. The specific nature of the unoccupied Ni 3d-derived σ-MO is a consequence of donor-acceptor chemical bonding in [Ni(Salen)].

A hetero-tetranuclear CeNi3 complex with a macrocyclic ligand catalysed the aerobic oxygenation of a methylene group adjacent to a carbonyl group under visible-light radiation to produce the corresponding α-diketones. The visible-light induced homolysis of the Ce–O bond of a bis(enolate) intermediate is proposed prior to aerobic oxygenation.

The tetradentate salen ligand derived from (±)-trans-1,2-diaminocyclohexane and 2-hydroxy-4-dimethylaminobenzaldehyde is prepared and its complexes with Co(II), Cu(II), Ni(II), and Pd(II) are synthesized. The ligand is fully characterized by FTIR, 1H and 13C NMR and mass spectrometry. Structures of the metal complexes are determined by single crystal X-ray diffraction. With the exception of the Co complex that crystallizes in the monoclinic system (space group P21/c), all the other complexes crystallize in the triclinic system with the space group P-1. All the complexes have slightly distorted square planar geometries. The ligand and the metal complexes are screened for their in vitro anticancer activity against the human breast cancer cell lines MCF-7 and T47D. In comparison with the uncomplexed ligand, the cobalt complex shows a marked antiproliferative effect.

A biocompatible zinc (II) complex based on a tetradentate N,N,O,O-type salen ligand was synthesized, characterized and used for the solvent-free ring-opening polymerization (ROP) of L-lactide in bu...

Disruption of copper homeostasis is associated with a number of severe diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), Wilson’s disease, and Menkes syndrome. Given this association, the detection and capture of Cu2+ in biological fluids and tissues may provide a new direction for the diagnosis and treatment of related disorders. The current analytical approaches, however, are challenging due to the high cost, complexity, and long time required to prepare and analyze samples. Here, we report a novel salen ligand, namely N,N’-(1,2-phenylene)bis(1-(1H-imidazol-4-yl)methanimine) (pimi), which can readily detect and concurrently capture Cu2+ from aqueous as well as biological mediums. Pimi can selectively and specifically detect Cu2+ from biofluid and cellular samples with rapid ccresponse time (

A new dinuclear uranyl salen coordination compound, [(UO2)2(L)2]·2MeCN [L = 6,6'-((1E,1'E)-((2,2-dimethylpropane-1,3-diyl)bis(azaneylylidene))-bis(methaneylylidene))bis(2-methoxyphenol)], was synthesized using a multifunctional salen ligand to harvest visible light for the selective photocatalytic reduction of CO2 to MeOH. The assembling of the two U centers into one coordination moiety via a chelating-bridging doubly deprotonated tetradentate ligand allowed the formation of U centers with distorted pentagonal bipyramid geometry. Such construction of compounds leads to excellent activity for the photocatalytic reduction of CO2, permitting a production rate of 1.29 mmol g-1 h-1 of MeOH with an apparent quantum yield of 18%. Triethanolamine (TEOA) was used as a sacrificial electron donor to carry out the photocatalytic reduction of CO2. The selective methanol formation was purely a photocatalytic phenomenon and confirmed using isotopically labeled 13CO2 and product analysis by 13C-NMR spectroscopy. The spectroscopic studies also confirmed the interaction of CO2 with the molecule of the title complex. The results of these efforts made it possible to understand the reaction mechanism using ESI-mass spectrometry.

This work describes the application of a library of iron(III)-salen catalysts in the production of biodiesel from vegetable oils. The conversion of neutral soybean oil is complete within two hours at 160–180 °C with low catalyst loading (0.10 mol%). A comparative screening reveals that the catalysts containing acetate as a fifth ligand are the most performing, and these have been conveniently used to convert acidic and waste cooking oils (WCO). WCOs were used as received without further purification to produce biodiesel in high yield (85–90%) under optimized conditions (2 h at 180 °C, catalyst loading 0.1 mol%, oil to alcohol molar ratio 1:20). The iron content in the lipophilic and hydrophilic phases of the crude mixture was investigated and the residual concentration in biodiesel was found to be in the order of 10–14 ppm, comparable to that contained in biodiesels from other sources. Graphical Abstract

A novel phenoxo-bridged zinc complex, [Zn2(L)µ(O-O)2H2OCl2] [L= deprotonated salen ligand, 2,2′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azaneylylidene))bis(methaneylylidene))diphenol), was reported. The title complex was characterized by elemental analyses, single crystal X-ray crystallography, spectroscopic studies, and thermogravimetric analysis. The X-ray structure analysis reveals the coordination of Zn1 atom to two imine nitrogen atoms, two phenolic oxygen atoms, and the oxygen atom of aqua ligand, giving it a distorted square pyramidal geometry, whereas the Zn2 atom is bonded to the same phenoxide anions, and two chloride ions, resulting in a distorted tetrahedral geometry. In addition, TD-DFT and NBO analyses were investigated to obtain bonding information insights into the structure. Furthermore, Hirshfeld surface analysis was used to determine various intermolecular interactions in the complex. Furthermore, a docking analysis was performed on the B-DNA [sequence d (CGCGAATTCGCG)2dodecamer] (PDB ID:1BNA) using the AutoDockvina (scripps) software package. The fluorescence property of the title complex was also carried out, and revealed it to be excellent photoluminescent material.

International audience; The controlled preparation of chiral emissive transition metal complexes is fundamental in the field of circularly polarized luminescence (CPL) active molecular materials. For this purpose, enantiopure Zn(II) complexes 1 and 2 based on a tetradentate salen ligand surrounded by [4]helicene moieties, together with their racemic counterpart 3, have been herein synthesized. Chirality is primarily brought about by chiral 1,2-cyclohexane-diamines. Alternatively, achiral complex 4 based on ortho-phenylene-diamine has been prepared as well. Single crystal X-ray diffraction analyses have been performed on helicenic intermediates 8 and 9 and complexes 1 and 4. Complexes 1 and 4 display the typical tetradentate O,N,N,O coordination around Zn(II) characteristic of salen ligands, and bear two [4]helicene moieties. The zinc complexes are luminescent in the visible range around 560 nm at room temperature in aerated solutions with the QY reaching ca. 15% for a luminescence lifetime of 5.5 ns. The optical activities of these complexes have been assessed by CD and CPL, and compared to DFT calculations.

Accompanied by a change in color from red to black, the enantiomorphic phases of the cobalt complexes of a chiral salen ligand (L2-, Co(L)center dot CS2, and Co(L) (L = L-S,L-S or L-R,L-R)) chemisorb NO (g) at atmospheric pressure and rt over hours for the CS2 solvated phase, and within seconds for the desolvated phase. NO is installed as an axial nitrosyl ligand. Aligned but unconnected voids in the CS2 desorbed Co(L-R,L-R)center dot CS2 structure indicate conduits for the directional desorption of CS2 and reversible sorption of NO, which occur without loss of crystallinity. Vibrational circular dichroism (VCD) spectra have been recorded for both hands of LH2, Zn(L), Co(L)center dot CS2, Co(L), Co(NO)(L), and Co(NO)(L)center dot CS2, revealing significant differences between the solution-state and solid-state spectra. Chiral induction enables the detection of the nu(NO) band in both condensed states, and surprisingly also the achiral lattice solvent (CS2 (nu(CS) at 1514 cm(-1))) in the solid-state VCD. Solution-state spectra of the paramagnetic Co(II) complex shows a nearly 10-fold enhancement and more extensive inversion of polarity of the vibrations of dominant VCD bands compared to the spectra of the diamagnetic compounds. This enhancement is less pronounced when there are fewer polarity inversions in the solid state VCD spectra. Accompanied by a change in color from red to black, the enantiomorphic phases of the cobalt complexes of a chiral salen ligand (L2−, Co(L)·CS2, and Co(L) (L = LS,S or LR,R)) chemisorb NO (g) at atmospheric pressure and rt over hours for the CS2 solvated phase, and within seconds for the desolvated phase. NO is installed as an axial nitrosyl ligand. Aligned but unconnected voids in the CS2 desorbed Co(LR,R)·CS2 structure indicate conduits for the directional desorption of CS2 and reversible sorption of NO, which occur without loss of crystallinity. Vibrational circular dichroism (VCD) spectra have been recorded for both hands of LH2, Zn(L), Co(L)·CS2, Co(L), Co(NO)(L), and Co(NO)(L)·CS2, revealing significant differences between the solution-state and solid-state spectra. Chiral induction enables the detection of the νNO band in both condensed states, and surprisingly also the achiral lattice solvent (CS2 (νCS at 1514 cm−1)) in the solid-state VCD. Solution-state spectra of the paramagnetic Co(II) complex shows a nearly 10-fold enhancement and more extensive inversion of polarity of the vibrations of dominant VCD bands compared to the spectra of the diamagnetic compounds. This enhancement is less pronounced when there are fewer polarity inversions in the solid state VCD spectra

The Co(III)-catalyzed reaction of 1,3-dicarbonyl compounds with 2-(diazoacetyl)-2H-azirines, prepared by a simplified procedure from 2H-azirin-2-carbonyl chlorides, led in high yields to the formation of 2-(diazoacetyl)pyrroles, while leaving the diazoacetyl function intact. The intramolecular aromatic substitution reaction of 2-(diazoacetyl)pyrroles, catalyzed by Cu(OTf)2, provided selectively previously unknown benzo[e]- and hetero[e]-fused indol-7-oles in good yields. Formylation of benzo[e]indol-4-ol led selectively to the 5-formyl derivative, which is a good precursor for an unusual salen ligand and its Ni-complex. Triflates prepared from benzo[e]indol-4-oles gave various 4-substituted benzo[e]indoles carrying aryl, 2-thienyl, 2-pyridyl, and alkynyl groups, in excellent yields using cross-coupling reactions. 4-(2-Pyridyl)benzo[e]indoles, upon treatment with BF3·Et2O/Et3N, afforded a new type of fluorescent boron complexes with large Stokes shifts.

This work deals with the synthesis, spectroscopic studies and catalytic evaluation of the novel chiral salen (L1H2) and (L2H2) ligands and their chiral boronate [L1(B1-4)] and [L2(B1-4)] complexes. Initially, the reaction of 5-azidomethyl salicylaldehyde and (R)-(−)-2-amino-1-butanol in absolute ethanol afforded a new chiral salen ligand (L1H2). Then, a novel chiral salen ligand (L2H2) have been prepared from chiral salen ligand (L1H2) for the synthesis of boronate [L2(B1-4)] complexes through click reaction approach under ambient conditions. The reaction of chiral salen (L1H2) and (L2H2) ligands with various boronic acids afforded a new tetra-coordinated mononuclear chiral boronate [L1(B1-4)] and [L2(B1-4)] complexes. All the compounds are remarkably stable crystalline solids and were obtained in good yields. For the full characterization of newly synthesized chiral salen ligands and their boronate complexes, the FT-IR, UV–Vis, NMR (1H, 13C, and 11B), LC-MS, and elemental analysis techniques have been used. The well-shaped chiral boronate compounds were investigated as catalyst for the asymmetric transfer hydrogenation (ATH) of aromatic ketones under appropriate settings. Particularly, it was proved that the ferrocene-based boronate compounds can afford an efficient catalytic conversion compared to the other boronate complexes in the asymmetric transfer hydrogenation catalytic studies.

A new derivative of dioxouranium(VI) salen complex, [UO2(L)(pyridine)], where [L = N,N′-Bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine] is synthesized and characterized by elemental analysis (C, H, N), FT-IR, ESI-MS spectrometry, UV/Vis, fluorescence, 1H and 13C NMR spectroscopy and thermal gravimetric (TG) study. Furthermore, the single crystal X-ray diffraction measurements of the complex were carried out at 100 and 273 K. The crystal structure measurements revealed that the complex has distorted pentagonal bipyramidal geometry with uranium atom located at the centre and bonded to two phenoxy oxygen and two azomethine nitrogen in tetradenate fashion and one nitrogen from pyridine making it seven coordinated. In addition, the photoluminescence property of the complex was also recorded. Keywords: Uranyl complex, Crystal structure, Photoluminescence

The H2O2 oxidation of l -cysteine and s-alkyl- l -cysteines (s-met- l -cys, s-et- l -cys & s-pro- l -cys) catalyzed by iron(III)–salen (salen = N,N′-bis(salicylidene)ethylenediaminato) complexes in aqueous CH3CN proceeds through Michaelis–Menten kinetics. The rate constant (k) values correlate well with Hammett σ constants, which gives the positive reaction constant (ρ = 1.5–1.9) value. The CV of oxoiron(IV)-salen ion shows a clear oxidation peak at 1.28 V in 0.1 M phosphate buffer (PB) solution using 0.1 M tertiary butyl ammonium perchlorate (TBAP) as supporting electrolyte at 266 K. The rate of the reaction is highly sensitive to the length of the alkyl chains present in the l -cysteines, pH and solvent composition of the medium. The calculated binding constant values (Kf) in the range of 117–613 M−1, indicate that iron(III)–salen complexes carrying electron donating substituents in the salen ligand have higher binding constant values compared to those carrying electron withdrawing substituents. Product analysis shows the conversion of l -cys to its disulfide and s-alkyl- l -cys to the corresponding sulfoxides. Based on the spectral and kinetic data the plausible mechanism has been proposed.

A new salen ligand with an anchoring free amine functional group in the ligand backbone and the corresponding NiII complex [NiIILNH2] (1) were synthesized and characterized. The complex effectively reduced CO2 to C1 (HCOOH, CH3OH) and C2 (C2H5OH) products in a simple H-type reactor upon immobilization on the graphite electrode. Initially HCOOH was formed which was further reduced to CH3OH and C2H5OH in a 6e− and 12e− transfer pathway. An overall current efficiency of 49% was recorded for the formation of alcohols at −1.80 V vs. Ag/AgCl in aqueous media (ERC time 1 h, pH 7.0 and KHCO3 0.5 M). Thus, the common limitation of the formation of deeply reduced C2 products has been overcome. The effect of the anchoring free amine group was further established by examining the CO2 reduction efficiency of the similar NiII complex without having the tethered –NH2 group. The lack of alcohol production for this case highlighted the importance of the anchoring group with the electrodes during electrochemical reduction.

Two novel Zn2Dy2 Schiff base cluster complexes composed of [DyZn2(salen)2Cl2]+ and [Dy(bpdc)2]− complex-fragment building blocks (bpdc2− = 2,2′-bipyridine-6,6′-dicarboxylate) have been prepared, which exhibit interesting T-shaped metal cores and ferromagnetic interactions. Two-step magnetic relaxation was observed under a 1500 Oe dc field for both cluster complexes, and their effective energy barrier can be regulated by the bis-imine chain in the Schiff base. Complex 1, [Dy2Zn2(La)2(bpdc)2Cl2)]·3MeOH [H2La = N,N′- bis(3-methoxysalicylidene)-1,3-diaminopropane], has the Ueff/k value of 20.2(0.3) K and the τ0 value of 6.7(0.2) × 10−8 s for the fast relaxation (FR) phase as well as the Ueff/k value of 243.2(4.9) K and the τ0 value of 6.0(0.3) × 10−10 s for the slow relaxation (SR) phase; while complex 2, [Dy2Zn2(Lb)2(bpdc)2Cl2)]·MeOH·H2O [H2Lb = N,N′-bis(3-methoxysalicylidene)-1,2-diaminoethane], possesses the Ueff/k value of 22.0(0.4) K and the τ0 value of 4.6(0.1) × 10−8 s for the FR phase as well as the Ueff/k value of 205.7(4.4) K and the τ0 value of 1.7(0.2) × 10−9 s for the SR phase. Furthermore, the two complexes exhibit dual emission centered on not only the lanthanide(III) ion but also the ligand in the visible region, of which the metal-centered emission is closely related to the length of the bis-imine chain on the salen ligand. The average fluorescence lifetime (τ) of 1 (10.6 ns) is an order of magnitude longer than that of 2 (0.86 ns).

4-(Diethylamino) salicylaldehyde based Salen ligands were synthesized and studied using density functional theory (DFT) employing B3LYP/6-31G(d) method. These dyes exhibited intramolecular charge transfer (ICT) which were examined for their photophysical properties. They show red to deep red absorption and emission respectively in the range of 562–575 nm and 596–635 nm and exhibited positive solvatochromism which is supported by linear and multi-linear regression analysis. Oscillator strengths and transition state dipole moments are studied to understand charge transfer (CT) characteristics. These deep red emissive fluorophores showed aggregation-caused quenching (ACQ). The spectral variations were analyzed by linear solvation energy relationships proposed by Kamlet-Taft and Catalan which indicated that solvent polarizability/dipolarity influences more compared to solvent acidity or basicity. Bathochromic shift in emission and increase in dipole moment in the excited state signify ICT character. The calculated electronic spectra of dyes are elucidated on the basis of TD-DFT calculations. Spectroscopic and computational methods were used to obtain linear polarizability, hyperpolarizability of the dyes and have better NLO properties than urea. Molecular Electrostatic Potential (MEP), NBO, HOMO-LUMO analysis, global chemical reactivity descriptors are studied at same level DFT.

The crystal structure of a second phase, which results from packing polymorphism, is described for a previously reported MnIII complex., The crystal structure of the title complex (systematic name: trans-aqua­chlorido­{2,2′[ethane-1,2-diylbis(nitrilo­methyl­idyne)]diphenolato-κ4 O,N,N′,O′}manganese(III) monohydrate), [Mn(C16H14N2O2)Cl(H2O)]·H2O has been reported previously in the space group P21/n [Panja et al. (2003 ▸). Polyhedron, 22, 1191–1198]. We obtained the same hydrated complex through an alternative synthesis, and crystallized a new polymorph, in the space group P21. The mol­ecular conformation of the complex is virtually unmodified, but the absence of the glide plane in the new polymorph halves the unit-cell parameter c, affording a non-centrosymmetric crystal structure with Z = 2, while the previously reported crystal is centrosymmetric with Z = 4. Both phases represent a case of packing polymorphism, similar to other dimorphic crystal structures retrieved from the Cambridge Structural Database.

The crystal structures of the title compounds have been studied to clarify the characteristics of the NO2 − ligand as a C—H⋯O hydrogen-bond acceptor, in relation to the solid-state photochemical linkage isomerization., The reaction cavities of the nitro groups in the title compounds, trans-{2,2′-[ethane-1,2-diylbis(nitrilo­methyl­idyne)]diphenolato-κ4 O,N,N′,O′}(nitro-κN)(pyridine-κN)cobalt(III), [Co(C16H14N2O2)(NO2)(C5H5N)], (I), and trans-{2,2′-[ethane-1,2-diylbis(nitrilo­methyl­idyne)]diphenolato-κ4 O,N,N′,O′}(4-methyl­pyridine-κN)(nitro-κN)cobalt(III), [Co(C16H14N2O2)(NO2)(C6H7N)], (II), have been investigated to reveal that the inter­molecular CMe—H⋯O(nitro) contacts in (II) are unfeasible for the nitro–nitrito photochemical linkage isomerization process. In (I), there are two independent complexes showing similar conformations, and the central five-membered chelate ring of the tetra­dentate salen ligand adopts the same absolute configuration. This is the result of pseudo-spontaneous resolution, since the configuration of the five-membered chelate ring may frequently be reversed in solution. In the crystals of (I) and (II), the mol­ecules are linked into three-dimensional networks by C—H⋯O hydrogen bonds.

Manganese(iii) salen has been developed as a new catalytic motif for alcohol dehydrogenation and the mechanism has been elucidated., The first example of a manganese(iii) catalyst for the acceptorless dehydrogenation of alcohols is presented. N,N′-Bis(salicylidene)-1,2-cyclohexanediaminomanganese(iii) chloride (2) has been shown to catalyze the direct synthesis of imines from a variety of alcohols and amines with the liberation of hydrogen gas. The mechanism has been investigated experimentally with labelled substrates and theoretically with DFT calculations. The results indicate a metal–ligand bifunctional pathway in which both imine groups in the salen ligand are first reduced to form a manganese(iii) amido complex as the catalytically active species. Dehydrogenation of the alcohol then takes place by a stepwise outer-sphere hydrogen transfer generating a manganese(iii) salan hydride from which hydrogen gas is released.

The crystal structure of [Al(tBu-salen)]2O·HCl shows major changes compared to that of [Al(tBu-salen)]2O. The additional proton is localized on the bridging oxygen atom, making the aluminium atoms more electron deficient. As a result, a water molecule coordinates to one of the aluminium atoms, which becomes six-coordinate. This pushes the salen ligand associated with the six-coordinate aluminium ion closer to the other salen ligand and results in the geometry around the five-coordinate aluminium atom becoming more trigonal bipyramidal. These results experimentally mirror the predications of DFT calculations on the interaction of [Al(tBu-salen)]2O and related complexes with carbon dioxide. Variable temperature NMR studies of protonated [Al(tBu-salen)]2O complexes revealed that the structures were dynamic and could be explained on the basis of an intramolecular rearrangement in which the non-salen substituent of a five-coordinate aluminium(tBu-salen) unit migrates from one face of a square based pyramidal structure to the other via the formation of structures with trigonal bipyramidal geometries. Protonated [Al(tBu-salen)]2O complexes were shown to have enhanced Lewis acidity relative to [Al(tBu-salen)]2O, coordinating to water, dioxane and 1,2-epoxyhexane. Coordinated epoxyhexane was activated towards ring-opening, to give various species which remained coordinated to the aluminium centers. The protonated [Al(tBu-salen)]2O complexes catalysed the synthesis of cyclic carbonates from epoxides and carbon dioxide both in the presence and absence of tetrabutylammonium bromide as a nucleophilic cocatalyst. The catalytic activity was principally determined by the nature of the nucleophilic species within the catalyst structure rather than by changes to the Lewis acidity of the metal centers.

International audience; (R)-1,2-Diaminobicyclo[2.2.2]octane was used as a starting material for the preparation, in solution or in a ball mill, of a salen ligand. Five metal salen complexes were prepared in high yield and their cytotoxic activities were evaluated against the Human Colon cancer HCT116 cell lines. The original manganese salen complex displayed the highest activity with a potency 16 fold higher than that of cisplatin, demonstrating the benefit of the bridging backbone compared to other salen systems. An alternative preparation route for this complex by mechanochemistry was also performed.

The design of nanostructured catalysts based on earth‐abundant metals that mediate important reactions efficiently, selectively and with a broad scope is highly desirable. Unfortunately, the synthesis of such catalysts is poorly understood. We report here on highly active Ni catalysts for the reductive amination of ketones by ammonia employing hydrogen as a reducing agent. The key functions of the Ni‐salen precursor complex during catalyst synthesis have been identified: (1) Ni‐salen complexes sublime during catalyst synthesis, which allows molecular dispersion of the metal precursor on the support material. (2) The salen ligand forms a nitrogen‐doped carbon shell by decomposition, which embeds and stabilizes the Ni nanoparticles on the γ‐Al2O3 support. (3) Parameters, such as flow rate of the pyrolysis gas, determine the carbon supply for the embedding process of Ni nanoparticles.

A new ligand H2L with pyridine and salen moieties and its coordination polymers (CPs) [Mn(L)Cl]·DMF (1) and [Fe(L)Cl]·DMF (2) were synthesized and their photocatalytic activity for the conversion of CO2 into CO under visible-light irradiation was investigated. This is the first instance of pyridyl-salen-ligand based CPs for photocatalyzing CO2 reduction.

A bis-hypochlorite adduct of a manganese(IV) salen complex having a chiral (R,R)-cyclohexane-1,2-diamine linkage (2-tBu) is successfully prepared and characterized by various spectroscopic methods. The reactions of 2-tBu with various organic substrates show that 2-tBu is capable of sulfoxidation, epoxidation, chlorination, and hydrogen abstraction reactions. However, the enantioselectivity of the epoxidation reactions by 2-tBu is much lower than that reported for the catalytic reactions by Jacobsen’s catalyst. The low enantioselectivity is consistent with a planar conformation of the salen ligand, which is suggested by circular dichroism spectroscopy. This study suggests that 2-tBu is not a reactive intermediate of Jacobsen’s enantioselective epoxidation catalysis.

Salen-based indium triads, [{(3-tBu)2-(5-Mes2B)2-salen}In-Me] (1) and [{(3-tBu)2-(5-Mes2Bphenyl)2-salen}In-Me] (2), bearing triarylborane (TAB) units were prepared and fully characterised by NMR spectroscopy and elemental analysis. The major absorption bands of 1 and 2 appeared in the region centred at 347 nm and 374 nm, respectively, and the intense emission spectra were observed in the sky blue (λem = 491 nm for 1) and bluish-green (λem = 498 nm for 2) regions, respectively. The solvatochromism effects in various organic solvents and computational calculation results strongly suggested that these absorption and emission features are mainly attributed to intramolecular charge transfer (ICT) transitions between the salen ligand moieties and the TAB units. Furthermore, UV-vis and photoluminescence (PL) titration experiments by the addition of fluoride anions demonstrated ratiometric quenching patterns in both the absorption and emission spectra, indicating that binding of the fluoride anion to the boron centres interrupts these ICT transitions in each compound. Interestingly, both triads exhibited a gradual red-shifted response in each emission spectrum upon the addition of the fluoride anions, resulting in a dramatic colour-change to yellow. The computational calculation results of the S1 states revealed that these emission-colour change properties arise from the elevation of HOMO levels, which are mainly localised on the TAB moieties, resulting from the fluoride anion binding to the borane centres.

A dimethylformamide bound mononuclear dioxouranium(VI) salen based complex with propylene linkage is prepared from a salen ligand, H 2 L, 2,2-(1E,1E)-(2,2-dimethylpropane-1,3-diyl)bis(azanylylidene)bis(methanylylidene)diphenol. The structure of the reported uranyl complex is established by elemental analysis (C, H, N), FT-IR and NMR spectroscopic methods, and single crystal X-ray diffraction measurements. The X-ray diffraction analysis shows that the crystal is monoclinic with space group P2 1 /n (no. 14), a = 7.99198(6) A, b = 12.14896(9) A, c = 23.76987(19) A, β = 97.4163(7)°. Furthermore, to obtain insights into the structure, DFT calculations have been made employing 6-31G (d,p) and GENECP basic sets. The findings obtained from the theoretical calculations are quite close with the results obtained from the experimental data.

The title compounds are differing only by the position of the chlorine atom in the benzene ring. The mol­ecular structures are very similar, except for the relative position of the hy­droxy­phenyl rings., The title compounds, C23H21ClN2O2, differ from each other only by the position of the Cl atom on the corresponding benzene ring: meta relative to the central sp 3 C atom for (I) and para for (II). In (I), the hy­droxy­phenyl rings are almost parallel, the dihedral angle between the mean planes being 9.2 (2)°, but in (II), the relative position of the ring is different, characterized by a dihedral angle of 48.5 (1)°. Compound (I) features intra­molecular O—H⋯N and inter­molecular C—H⋯O hydrogen bonds, while in (II), intra­molecular O—H⋯N, C—H⋯N hydrogen bonds and weak inter­molecular C—H⋯π inter­actions are observed. Compound (I) was refined as an inversion twin.

Several aluminium alkyl and alkyloxide complexes supported by a thioether-bridged salen ligand were synthesized by the protonolysis reaction. Reactions of N,N’-bis(3,5-di-tert-butylsalicylidene)-2,2’-diaminophenylsulfide (H2L) with one or two equivalents of AlMe3 in toluene at 100 °C afforded the corresponding mono- and binuclear aluminium methyl complexes LAlMe (1) and L(AlMe2)2 (2). Treatment of the in situ generated complex 1 with one equivalent of ROH (R = PhCH2, iPr, CH3OCH2CH2) produced the desired aluminium alkyloxide complexes LAlOCH2Ph (3), LAl(OiPr) (4) and LAlO(CH2)2OCH3 (5). All the molecular structures were established by single crystal X-ray diffraction studies. It was found that aluminium alkyloxide complexes 3-5 showed higher catalytic activity for the homopolymerization of e-caprolactone (e-CL) than corresponding aluminium methyl complexes 1 and 2. Furthermore, these alkyloxide complexes were also efficient initiators for the copolymerization of L-lactide and e-CL to give practically random copolymers.

A series of bifunctional metal-salen complexes bearing ionic liquid substituents were investigated as catalysts for the synthesis of cyclic carbonates from carbon dioxide (CO2) and epoxides using density functional theory (DFT) and energy span model. Detailed studies reveal that the three-step mechanism involving the ring-opening of propylene oxide (PO), CO2 insertion, and ring-closure to the cyclic carbonate is kinetically more favorable than the two-step mechanism. The effect of ionic liquids, epoxide substituents and metal center of the metal-salen complexes were explored. Amino functionalized ionic liquids substituents tethered to the salen ligand of the metal-salen complexes performed well. Epoxide substituents affect the cycloaddition mainly through the electronic effect and the substituent that lowers the negative charges of the ring carbon atom to be attacked favors the cycloaddition. When the salen ligand is fixed, the catalytic activity metal-salen complexes can be measured by the interaction between the oxygen atom (O) of epoxides and the central metal (M) and there is a linear relationship between the energy span and the M-O bond length, which can be used as a descriptor to screen CO2 conversion catalysts.

A panel of stable ruthenium carbene complexes bearing a tetradentate salen ligand, with their carbene-C atom adjacent to heteroatom, were synthesized from cis-β-Ru(II)-bis(CO) complex by reacting with the corresponding carbene precursors. These carbene complexes, which were fully characterized by elemental analysis, NMR, IR spectroscopy and X-ray-crystal structure determination, all adopt a cis-β configuration; the heteroatom (N or O) adjacent to the carbene C atom contributes to the high stability of these complexes both in solution and in solid state. DFT calculations were also performed to gain insight into the Ru-Ccarbene bonds.

An inexpensive and effective cobalt coordinated conjugated microporous polymer (Co-CMP-2) made up from cross-linked an ethanediamine-based salen ligand with 1,3,5-triethynylbenzene. Co-CMP-2 exhibited extremely high catalytic efficiency in the synthesis of cyclic carbonates from CO2 and epoxides, which is superior to that of previously reported Co-CMP. Co-CMP-2 achieved a TOF of 23300 h−1 for ethylene carbonate. Moreover, the catalyst can be reused more than 10 times without significant loss in activity.

A Pd(II)-salen complex derived from salen ligand is reported. The reported complex is investigated by microanalyses (C, H, N), ESI-MS spectrometry, FT-IR, 1H and 13C NMR and UV/Vis spectroscopic studies. In addition, crystal structure measurement study has also been carried out in order to confirm the structure of Pd(II)-salen complex. In order to explore the insights into the structural bonding of the studied complex, computational measurements has been carried out. Combined topology and NBO studies were made to explore the nature of Pd O and Pd N bonding in the complex. The natural charges showed that the transfers of the negative charge from the ligand to palladium atom is at 1.4157–1.4312 e. Atom in a molecule (AIM) analysis showed the electron density (ρ(r) > 0.1) and its Laplacian ( ∇ 2 ρ(r) > 0). These topological parameters showed that covalent bonding interactions are dominant in Pd N and Pd O bonds. However, Pd N bonds have more covalent characters than Pd O bonds, which is further confirmed by the ratio of local electron potential energy density to the local electron kinetic energy density (|V(r)|/G(r)) found to be higher for Pd N bonds (1.1683–1.1993) as compared to Pd O bonds (1.0689–1.0926). AIM and NBO reveal that shorter Pd N and Pd O bonds have higher interaction energies (Eint) and hence higher bond covalence.

The metal–organic framework (MOF) Cu4(mpbatb)2 (mpbatb-4,4′,4″,4‴-(1,3-phenylenebis(azanetriyl))tetrabenzoate), also known as DUT-71 (DUT – Dresden University of Technology), was functionalized via postsynthetic cross-linking of the copper paddle wheels by linear salen derivatives and dabco (1,4-diazabicyclo[2.2.2]octane). This results in a series of porous MOFs, denoted as DUT-117(M) (M – Cu, Ni, Pd). Besides significant improvement of the framework robustness, the influence of the metal coordinated by the salen ligand on the gas adsorption capacity (hydrogen –196 °C, methane 25 °C, and carbon dioxide 25 °C) was investigated. In this series DUT-117(Ni) stands out as the best material for adsorptive methane storage with a high working capacity of 171 cm3·cm–3 between 5 and 65 bar.

A variety of unique Al(salen) complexes functionalized by imidazolium-based ionic liquid (IL) moieties with the salen ligand at the two sides of 3,3′-position have been successfully prepared, rather than familiar 5,5′-position reported previously. The catalytic activity obtained by these bifunctional catalysts could be superior to those of the binary type catalysts in the formation of five-membered heterocyclic compounds from the cycloaddition reaction of CO2 and three-membered heterocyclic compounds (including terminal epoxides and N -substituted aziridines), presumably due to the distinguished intramolecularly synergistic catalysis, which might lead to perform the cycloaddition reaction at ambient conditions and retain excellent yield and unprecedented chemo- or regioselectivity. Moreover, the polyether-based trifunctional Al(salen) catalysts with the best catalytic performance could be regenerated and reused at least eight times without any obvious decreases in catalytic activity. Finally, the kinetic investigation suggested the structure of catalysts had important influences on the catalytic activity, thereby proposing the possible reaction mechanism.

A new zinc complex based on a tetradentate N,N,O,O-type coumarin salen ligand (H2L) was prepared and characterized by elemental analysis, thermogravimetric analysis (TGA), and FT-IR, UV–vis and 1H NMR spectroscopy. The complex [Zn(L)(H2O)]·H2O was active in the ring opening polymerization (ROP) of e-caprolactone under solvent-free conditions, producing polycaprolactone (PCL) with a molecular weight up to 17,700 g mol−1 and a narrow molecular weight distribution. 1H NMR analysis showed that the PCL obtained was mainly linear, having hydroxymethylene groups in the chain ends. Differential scanning calorimetry (DSC) showed that the polymer had high crystallinity (61%) and that TGA had a decomposition temperature above 300 °C.

In this research, a simple, efficient, inexpensive, rapid and high yield method for the purification of 6 × histidine-tagged recombinant protein was developed. For this purpose, manganese ferrite magnetic nanoparticles (MNPs) were synthesized through a co-precipitation method and then they were conveniently surface-modified with tetraethyl orthosilicate (TEOS) in order to prevent oxidation and form high density of hydroxyl groups. Next, the salen ligand was prepared from condensation reaction of salicylaldehyde and 3-aminopropyl (trimethoxy) silane (APTMS) in 1:1 molar ratio; followed by complexation with Ni(OAc)2.4H2O. Finally, the prepared Ni(II)-salen complex conjugated to silica coated MNPs and MnFe2O4@SiO2@Ni-Salen complex nanoparticles were obtained. The functionalized nanoparticles were spherical with an average diameter around 70 nm. The obtained MNPs had a saturation magnetization about 54 emu/g and had super paramagnetic character. These MNPs were used efficiently to enrich recombinant histidine-tagged (His-tagged) protein-A from bacterial cell lysate. In about 45 min, highly pure His-tagged recombinant protein was obtained, as judged by SDS-PAGE analysis and silver staining. The amount of target protein in flow through and washing fractions was minimal denoting the high efficiency of purification process. The average capacity of the matrix was found to be high and about 180 ± 15 mg g−1 (protein/MnFe2O4@SiO2@Ni-Salen complex). Collectively, purification process with MnFe2O4@SiO2@Ni-Salen complex nanoparticles is rapid, efficient, selective and whole purification can be carried out in only a single tube without the need for expensive systems.

Polymeric transition metal complexes with salen-type Schiff base ligands are considered as promising materials for modification of electrical double layer capacitor electrodes. Electrochemical properties of these polymers that define their performance in supercapacitors should be influenced by the ligand structure but this influence has never been systematically investigated. This article describes results of a comparative study of capacitance and charge transfer rate in polymeric nickel complexes with six different salen-type ligands using electrochemical impedance spectroscopy, analyzes advantages and limitations of this method vs. cyclic voltammetry, and provides some insights into the structure and morphology of nickel-salen type polymers. Analysis of results obtained by different analytical techniques shows that introduction of methoxy-substituents into the phenyl rings of the salen ligand and different substituents to the diamine bridge of the ligand causes noticeable changes in electrochemical properties of corresponding polymeric nickel complexes. Experimentally obtained values of gravimetric and volumetric capacitance, as well as effective charge diffusion coefficient provide guidelines for selection of most suitable nickel-salen type polymers for application in energy storage devices, including supercapacitors.

One-electron oxidized salen complexes of Mn(III) and Ni(II) were recently reported to be unique mixed-valence compounds. Their electronic structures are sensitive to the salen ligand and solvation. We systematically investigated a series of one-electron oxidized salen complexes of group 7 metals (Mn(III), Tc(III), and Re(III)) and their group 10 analogues (Ni(II), Pd(II), and Pt(II)) using the general multi-configuration reference quasi-degenerate perturbation theory (GMC-QDPT) which was combined with the three-dimensional reference interaction site model self-consistent field theory (3D-RISM-SCF) to incorporate the solvation effect. The calculated absorption spectra and electronic structures agree with the experimental observation. The one-electron oxidized salen complexes of group 10 metals with a symmetrical salen ligand have a delocalized electronic structure belonging to class III (Robin–Day classification) in weakly polar solvents. The tendency for taking a delocalized electronic structure increases in the order Pd(II) < Ni(II) < Pt(II). When the salen ligand is asymmetrical, the one-electron oxidized complexes have a localized electronic structure belonging to class II. The group 7 analogues of Mn(III) and Tc(III) have a localized electronic structure belonging to class II even in weakly polar solvents and even with a symmetrical salen ligand. However, the one-electron oxidized Re(III) complex has no mixed-valence nature because one-electron oxidation occurs on the Re center. Theoretical study shows that the solvation effect plays a crucial role in determining the mixed-valence character, class II or III, and thereby its incorporation in the calculation is indispensable for correctly describing geometries, electronic structures, and the inter-valence absorption spectra of these complexes. The d orbital energy is one of the most important factors for determining the localization/delocalization electronic structures in these complexes. Detailed discussion of these factors is presented.

The syntheses, structures and photoluminescence properties are reported for two new binuclear cyclometalated iridium(III) complexes, [Ir2(ppy)4(L)] (1) and [Ir2(F2-ppy)4(L)] (2) (ppy=2-phenylpyridine, F2-ppy = 2-(2,4-difluorophenyl)pyridine, H2L=N,N′-bis(2-hydroxynaphthyl methylidene)-2-hydroxy-1,3-propanediamine. X-ray crystal diffraction shows that L ligands adopt a tetradentate mode to bridge ir(III) ions to form binuclear structures. There are π-π stacking interactions between the binuclear structures, which results in the formation of 3D supramolecular networks. UV–vis absorption spectra and photoluminescence spectra show that the introduction of F− groups in the benzene rings of ppy ligands causes blue shift.

Microviscosity in living cells influences the diffusion of biomolecules and is an important physical parameter that related to cellular pathological processes. Although several fluorescent molecular rotors have been reported to work as intracellular microviscosity sensors, luminescent metal complexes have much less been studied. Herein we used zinc and aluminum complexes of Salen ligand ( N , N ′-thiophene-3,4-bis-4′-(diethylamino)-salicylimine) as fluorescent sensors for monitoring intracellular microviscosity. Although both of them showed enhanced fluorescence quantum yield along with increasing solvent viscosity, [AlSalen]+Cl− displayed higher sensitivity and stronger intracellular fluorescence signal, making it a better choice for intracellular application as microvisicosity sensor. Moreover, the fluorescence lifetime of [AlSalen]+Cl− also increased in higher viscosity environment, which has been demonstrated in monitoring microviscosity raising during incubating temperature decrease or autophagy process of HeLa cell via fluorescence lifetime imaging microscopy (FLIM).

A simple cooperative catalytic system was successfully developed for the solvent-free N-formylation of amines with CO2 and hydrosilanes under ambient conditions, which was composed of a Zn(salen) catalyst and quaternary ammonium salt. These commercially available binary components activated the Si-H bonds effectively, owing to the intermolecular synergistic effect between Lewis base and transition metal center (LB-TM), and subsequently facilitated the insertion of CO2 to form the active silyl formats, thereby leading to excellent catalytic performance at a low catalyst loading. Furthermore, the bifunctional Zn(salen) complexes, with two imidazolium-based ionic-liquid (IL) units at the 3,3'-position of salen ligand, acted as intramolecularly cooperative catalysts, and the solvent-regulated separation resulted in facile catalyst recycling and reuse.

Six new manganese(III) derivatives using the ligand H2MeOsalen: N,N′-ethylenebis(3-methoxysalicylaldiimine), have been synthesized and structurally characterized. In all cases the manganese ion is six-coordinated and occupies the internal cavity of the bicompartmental salen ligand. The manganese ion completes its coordination environment with one axial water molecule and one additional ligand, either water, ethanol or one acetate anion. The molecular unit is dimerized by the insertion of the coordinated water molecule into the external MeOsalen cavity of one neighbouring complex. This supramolecular dimer constitutes the structural basis for these compounds, the differences arising from the intermolecular hydrogen bonds involving the counter anions and crystallization solvent molecules. In this way, examples of pseudopolymorphism, cocrystallization and water/anion tapes held by the interaction with the complex dimers are described. The compound [{Mn(MeOsalen)K(H2O)0.5}2(μ-OOCMe)](PF6)3·HOCH2CH2OH is a heterometallic Mn/K derivative where the potassium ion occupies the external cavity, while the coordination of the manganese ion is completed by bridging acetate and ethyleneglycol ligands. The formation of ethyleneglycol is attributed to a stoichiometric oxidation of the ethanol solvent, attributed to the presence of the potassium ion in the complex.

International audience; We revealed a general guidance on preparation of electrochemically stable meso forms of nickel-salen based polymers suitable as new anode materials for electrochemical devices. Electrochemical performance of nickel-salen complexes, used as monomers of nickel-salen based polymers, was directly related to the salen ligand structure. We have considered it in specially designed and synthesized herein a new meso form of the nickel-salen polymer, vis., poly[meso-N,N 0-bis-(3-methylosalicylidene)-2,3butanediaminonickel(II)]. Then, electrochemical conditions for providing the environment appropriate for electropolymerization and charge transfer were optimized. In dependence upon the purpose of the use of the poly(meso-Ni-salen) films coated electrodes, it was possible to increase the amount of the charge stored in these conjugated polymer systems by proper tuning of both the chemical structure of the polymer and electrochemical conditions. Apparently, the charge transfer through nickel-salen polymers strongly depended upon steric hindrance between polymer layers, thus ensuring efficient counter ion doping. Therefore, this hindrance was carefully selected. We have defined steric requirements with respect to the type and position of moderately electrodonating substituents on imine bridges and phenolic rings of the nickel-salen polymers that must be met to achieve high conductivity and stability/durability during potential multi-cycling of the polymer films prepared.