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Manganese-based contrast agents (MnCAs) have emerged as suitable alternatives to gadolinium-based contrast agents (GdCAs). However, due to their kinetic lability and laborious synthetic procedures, only a few MnCAs have found clinical MRI application. In this work, we have employed a highly innovative single-pot template synthetic strategy to develop a MnCA, MnL , and studied the most important physicochemical properties in vitro. MnL displays optimized r relaxivities at both medium (20 and 64 MHz) and high magnetic fields (300 and 400 MHz) and an enhanced r =21.1 mM s (20 MHz, 298 K, pH 7.4) upon binding to BSA (K =4.2×10 M ). In vivo studies show that MnL is cleared intact into the bladder through renal excretion and has a prolonged blood half-life compared to the commercial GdCA Magnevist. MnL shows great promise as a novel MRI contrast agent. Me Me b −1 −1 3 −1 Me Me 1 1 a

Two Zn(II) complexes, K1 and K2, obtained from the template reaction of zinc(II) acetate dihydrate with o-phenylenediamine and 2-hydroxy-5-methylisophthalaldehyde (K1) or 2-hydroxy-5-tert-butyl-1,3-benzenedicarboxaldehyde (K2), respectively, were characterized by X-ray crystallography, spectroscopic (UV-vis, fluorescence and IR), and thermal methods. In the complex [Zn2(MeO)1.4(OH)0.6(L1)]·2H2O K1, there are two binding sites in the macrocyclic ligand and they are occupied by zinc(II) cations found in slightly distorted square pyramidal environment. The zinc(II) cations are connected by slightly asymmetric oxo bridges with a Zn1–O14–Zn1[−x, −y + 1, −z + 1] angle of 104.8(2)°. In the dimer [Zn2(CH3COO)2(L2)]·2EtOH K2, there are two crystallographically independent binding sites both occupied by zinc(II) cations. There is a significant difference between both complexes, since in K1 only one site is independent and the second is occupied due to the application of symmetry rules, and the geometry of both sites is identical. Thin layers of the obtained Zn(II) complexes were deposited on Si(111) by the spin coating method and studied by scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), fluorescence spectroscopy and ellipsometry. In the non-absorbing range, the value of the refractive index exhibits normal dispersion between 1.8 and 2.1 for K1_1–K1_3; and between 2.3 and 2.6 for the K2 series of samples established for long wavelengths (longer than 500 nm). The Zn(II) complexes and their thin layers exhibited fluorescence between 534–573 nm and 495–572 nm for the compounds and the layers, respectively. The highest quantum yield of fluorescence was achieved for K2 in benzene and in the solid state ϕ = 0.78 and 0.58, respectively. The influence of the solvent polarity on the fluorescence properties of the obtained complexes was studied. Additionally, DFT calculations were performed to explain the structures and electronic spectral properties of the complexes.

In this study, a novel anionic template polymer (TPAS) with microblock structure was prepared by ultraviolet light (UV)–assisted template copolymerization (UV-TP). Acrylamide (AM) and sodium styrene sulfonate (SSS) were selected as monomers and polypropylene ammonium chloride (PAAC) was chosen as the template. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), and thermogravimetry/differential scanning calorimetry (TG/DSC) were used to characterize the polymer chemical structure. The results showed that the attractive anionic microblock structure was formed in TPAS. Besides, the association constant (KM) and template reaction kinetics analysis results indicated that the polymerization reaction followed I (ZIP) template copolymerization mechanism. It proved the microblock structure formation again. The anionic microblock structure in TPAM could greatly improve the ability of charge neutralization, electrical patching, and bridging. After the hematite wastewater was conditioned by TPAS with this novel anionic microblock structure, the generated hematite flocs had larger particle size and denser structure. It was favorable for the reduction of turbidity, and the turbidity removal rate could reach 97.8%. TPAS showed excellent flocculation performance for hematite wastewater and had a broad market application prospect.

2-Hydroxybenzophenone-S-allyl-thiosemicarbazone and 3-allyl-salicylaldehyde were condensed by template effect of iron(III) ion to yield the N2O2 type-chelate complex. The S-allyl-thiosemicarbazone ...

A new cage cobalt(II) complex exhibiting a single-molecule magnet behavior has been synthesized by a template reaction on a metal ion as a matrix. The complex was characterized by elemental analysis and NMR spectroscopy. The magnetic properties have been studied by ac and dc magnetometry. The data obtained made it possible to determine the relaxation characteristics of this single-molecule magnet and compare them with those for a series of analogous recently reported cage cobalt(II) complexes.

As one of the core technologies employed in the field of sludge conditioning, flocculation has the ability to improve the sludge dewatering performance and reduce its volume and amount, which can accordingly result in lower costs in sludge transportation as well as subsequent disposal. Therefore, the development of new and high-efficiency flocculants is a hot topic in this field. The template copolymer (TPAD) of acryloyloxyethyl trimethyl ammonium chloride (DAC) and acrylamide (AM) was successfully synthesized through ultrasonic-template copolymerization using sodium-polyacrylate (NaPAA) as a template. The analysis of FTIR, 1H (13C) NMR, TG/DSC and SEM revealed that TPAD had a conspicuously significant cationic segmental structure. In addition, the results obtained from the analysis on the association constant (KM) and the kinetics of the template reaction indicated that the ultrasonic-template was a free radical initiated polymerization and the polymerization mechanism was I Zip-up (ZIP), and which once again confirmed the formation of the cationic fragment structure. This novel cationic fragment structure in TPAD greatly enhanced the ability of charge neutralization, electric patching, adsorption and bridging, thus improving the active sludge conditioning and dewatering performance (FCMC: 72.9%, SRF: 4.0 × 1012 m·kg−1, d50: 228.604 μm, Df: 2.02 at 400 r/min). The floc breakage and regeneration experiments showed that the cationic fragment structure in TPAD could make great contribution to the formation of large and dense floc structures, and these flocs were able to regenerate rapidly after breakage. Finally, it was also known that these large and compact floc structures were beneficial to the creation of more channels and voids, thereby decreasing sludge resistance (SRF) and improving sludge dewatering performance.

In this work, one-dimensional Ni-rich LiNi0.6Co0.2Mn0.2O2 microrod cathode material for lithium-ion battery has been firstly prepared by a simple stepwise oxalate co-precipitation method. Rod-like CoC2O4·2H2O formed in the first process is served as template for the formation of MC2O4·2H2O (M=Ni, Co, Mn) precursor, and the morphology of rod-like is maintained after the heat treatment with Li2CO3. The crystalline structure and morphology of the samples are characterized by XRD, SEM, and TEM/HRTEM. The electrochemical performances are evaluated by galvanostatic charge/discharge tests. With the beneficiation of micro/nanostructure, the LiNi0.6Co0.2Mn0.2O2 microrod cathode material shows an initial discharge capacity of 162, 134, 117, and 105 mAh g−1 at 0.1 °C, 1 °C, 3 °C, and 5 °C, respectively, and maintains 72.8% of its initial discharge capacity after 100 cycles at 1 °C.

Schiff-bases of metformin with each of salicylaldehyde (HL1); 2,3-dihydroxybenzaldehyde (H2L2); 2,4-dihydroxybenzaldehyde (H2L3); 2,5-dihydroxybenzaldehyde (H2L4); 3,4-dihydroxybenzaldehyde (H2L5) and 2-hydroxynaphthaldehyde (HL6) and their complexes with Pr(III) were synthesized by template reaction. The complexes were characterized through elemental analysis, conductivity and magnetic moment measurements, IR, UV-Vis., fluorescence, GC-MS and XRD spectroscopy. The complexes exhibit a series of characteristic emission bands for Pr3+ ion in the 481-472 and 590-580 nm range with a 318-332 nm excitation source. The complexes have eight coordinated structure with the formulae [PrL1-4,6(NO3)2(H2O)3].nH2O where n = 1, 1½, 3, 4, 4 and [PrL5(NO3)(H2O)5].2H2O. The suggested stereochemistry was confirmed using TGA, DTG and DTA analysis and a mechanism for thermal decomposition was proposed. Coates-Redfern equation was used to calculate kinetic and thermodynamic parameters of the main decomposition step. The utility of the complexes towards the detection of glucose at physiologically relevant pH in phosphate buffer using UV-Vis and fluorescence spectroscopy as well as viscosity measurements are tried where the association constants were calculated.

The complex nickel(II) anion comprises a pseudomacrocyclic hydrazide-based ligand with an L shape. In the crystal, such anions are connected with the potassium cations and the water solvent mol­ecules, forming a three-dimensional polymeric framework, which is stabilized by an extensive system of hydrogen bonds., The title compound, {[K4Ni2(C7H6N4O7)2]·4.8H2O}n, was obtained as a result of a template reaction between oxalohydrazide­hydroxamic acid, formaldehyde and nickel(II) nitrate followed by partial hydrolysis of the formed inter­mediate. The two independent [Ni(C7H6N4O7)]2– complex anions exhibit pseudo-C S symmetry and consist of an almost planar metal-containing fragment and a 1,3,5-oxadiazinane ring with a chair conformation disposed nearly perpendicularly with respect to the former. The central NiII atom has a square-planar N2O2 coordination arrangement formed by two amide N and two carboxyl­ate O atoms. In the crystal, the nickel(II) complex anions form layers parallel to the ab plane. Neighboring complex anion layers are connected by layers of potassium cations for which two of the four independent cations are disordered over two sites [ratios of 0.54 (3):0.46 (3) and 0.9643 (15):0.0357 (15)]. The framework is stabilized by an extensive system of hydrogen bonds where the water mol­ecules act as donors and the carb­oxy­lic O atoms, the amide O atoms and the oxadiazinane N atoms act as acceptors.

The title compound, poly[triaquabis[μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)]dinickel(II)tetrapotassium], [K4Ni2(C7H6N4O7)2(H2O)3] n , is a second solvatomorph of poly[(μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)nickel(II)dipotassium] reported previously [Plutenko et al. (2021). Acta Cryst. E77, 298–304]. The asymmetric unit of the title compound includes two structurally independent complex anions [Ni(C7H6N4O7)]2−, which exhibit an L-shaped geometry and consist of two almost flat fragments perpendicular to one another: the 1,3,5-oxadiazinane fragment and the fragment including other atoms of the anion. The central Ni atom is in a square-planar N2O2 coordination arrangement formed by two amide N and two carboxylate O atoms. In the crystal, the title compound forms a layered structure in which layers of negatively charged complex anions and positively charged potassium cations are stacked along the a-axis direction. The polymeric framework is stabilized by a system of hydrogen-bonding interactions in which the water molecules act as donors and the carboxylic, amide and water O atoms act as acceptors.

Although metal-organic frameworks (MOFs) have been reported as important porous materials for the potential utility in metal ion separation, coordinating the functionality, structure, and component of MOFs remains a great challenge. Herein, a series of anionic rare earth MOFs (RE-MOFs) were synthesized via a solvothermal template reaction and for the first time explored for uranium(VI) capture from an acidic medium. The unusually high extraction capacity of UO22+ (e.g., 538 mg U per g of Y-MOF) was achieved through ion-exchange with the concomitant release of Me2NH2+, during which the uranium(VI) extraction in the series of isostructural RE-MOFs was found to be highly sensitive to the ionic radii of the metal nodes. That is, the uranium(VI) adsorption capacities continuously increased as the ionic radii decreased. In-depth mechanism insight was obtained from molecular dynamics simulations, suggesting that both the accessible pore volume of the MOFs and hydrogen-bonding interactions contribute to the strong periodic tendency of uranium(VI) extraction.

International audience; This report explores the synthesis and spectral, structural, thermal, electrochemical, linear and nonlinear (NLO) properties of unsymmetrically-substituted N2O2 tetradentate Schiff base proligand and related bi and trimetallic Pd-II complexes. The diprotic proligand Fc-C(and xe001;O)CHand xe001;C(4-C6H4OH)NH-CH2CH2Nand xe001;CH-(2-OH,4-CO2H-C6H3) (2, Fc = ferrocenyl = (eta(5)-C5H5)Fe(eta(5)-C5H4))), is synthetized by condensation of the 4-hydroxyphenyl-appended ferrocenylenaminone 1 with 4-formyl-3-hydroxybenzoic acid. The related Pd(ii) complexes, neutral bimetallic 3 and ionic trimetallic 4, were both prepared via a three-component one-pot template reaction involving the half unit 1, palladium acetate, the CO2H-functionalized salicylaldehyde and the organometallic salicylaldehyde [Cp*Ru(eta(6)-2-OH-C6H4CHO)]PF6, respectively (Cp* = eta(5)-C5Me5). Compounds 2-4 were isolated as colored air and thermally stable solids in 74-86% yields. They were thoroughly characterized using various physicochemical tools, such as CHN analyses, IR, UV-vis, H-1 and C-13 NMR spectroscopy, TGA and cyclic voltammetry. The molecular structures of 3 and 4 were authenticated by single-crystal X-ray diffraction methods. In both 3 and 4, the four-coordinate palladium atom adopts a square planar geometry with two nitrogen and two oxygen atoms as donors occupying cis positions. Additionally in 4, the ferrocenyl and Cp*Ru+ moieties exhibit an anti-conformation with respect to the [Pd(N2O2] Schiff base platform. The electrochemical behavior of the two Pd(ii) complexes was investigated by cyclic voltammetry, showing in both cases a reversible redox process ascribed to the Fe(ii)/Fe(iii) couple of the dangling donor ferrocene. Compared to that for 3, the oxidation wave for 4 is anodically shifted by 30 mV, evidencing a greater electron accepting ability of Cp*Ru(+)vs. -CO2H. The second-order NLO responses of the push-pull derivatives 2-4 have been determined by harmonic light scattering measurements in N,N-dimethylformamide solutions at 1.91 mu m incident wavelength, and rather good quadratic hyperpolarisability beta values ranging from 120-160 x 10(-30) esu were determined.

The template reaction was performed between benzoylacetone-S-propylthiosemicarbazone and salicylaldehyde in the presence of Co(ClO4)2 and a square planar cobalt(II) complex, [Co(L)] (Co1) where L is a dibasic thiosemicarbazidato ligand was isolated. It was aimed to synthesize the octahedral cobalt complexes by using the co-ligands, pyridine and 2-amino pyridine. An octahedral cobalt(III) complex, [Co(L)(py)2]ClO4 (Co2), with two axial-pyridine ligands was obtained. Reaction with 2-amino pyridine gave an unexpected cobalt(III) centered structure, [Co(L1)]·H2O (Co3), where L1 is a new sixdentate (N4O2) ligand that yielded by the addition of the amino group of pyridine to the L ligand. L1 has tribasic thiosemicarbazidato structure that altered by the participation of an oxygen atom in addition to the amines. Experimental characterizations of three complexes have been completed using IR, NMR, UV–Vis, ESI-MS techniques and X-ray data. In order to better understand the intermolecular interactions of the structures, the Nonlinear Optical (NLO) properties and frontier orbitals (FMO) of the complexes were obtained using the Gaussian 09 program, DFT/B3LYP with 6–31 G (d, p) bas set for the C, N, O, H atoms and with LanL2DZ basic set for Co metal atom.

Three EuIII macrocyclic complexes [EuLnH2(NO3)3](H2O)x based on the ligands derived from 2 - hydroxy -5- methyl - 1,3 - benzenedicarbaldehyde and three different amines: o - phenylenediamine, Eu - OPDA; ethylenediamine, Eu - EDA; and 1,3 - diaminopropane, Eu - DAP have been synthesized via a metal template reaction. Eu - EDA and Eu - DAP showed metal based emission; for the Eu - OPDA complex these luminescent properties were not observed. From the photoluminescence emission measurements from ~13 to 300 K, the R/O = I (5D0 → 7F2)/I (5D0 → 7F1) ratio, together with two intensity parameters (Ω2 and Ω4), radiative lifetimes (τR) and branching ratios (β0 J′) were calculated based on the Judd - Ofelt theory, for Eu - EDA and Eu-DAP. While the behavior of these parameters for the Eu - DAP complex is temperature dependent, these remain constant for Eu - EDA. The temperature dependence observed for the Eu - DAP complex indicates that for temperatures below 120 K, the local symmetry of the EuIII center is modified, as compared to the environment of the same metal center at room temperature.

Co(II), Ni(II), and Cu(II) complexes with a Schiff base ligand pyridoxylidenetaurinate (L − ) were prepared by a template reaction of pyridoxal (3-hydroxy-5-(hydroxymethyl)-2-methylpyridine-4-carbaldehyde), taurine (2-aminoethane-1-sulfonic acid), and the corresponding metal acetate in water–ethanol solution. Composition of the product was [ML 2 (H 2 O) 2 ] for all three central metals. Coordination geometry varied from weakly distorted octahedral (Co, Ni) to strongly distorted octahedral (Cu) with trans arrangement of both water molecules and imine N atoms. Each bidentate ligand formed one chelate ring via iminic N and phenolic O donor atoms. The complexes were characterised by elemental analysis, FTIR spectroscopy, and XRD crystal and powder analyses. All complexes crystallize in monoclinic system with space group P 2 1 / c . IR spectra of the complexes showed changes typical for Schiff base coordination, comparing with IR spectrum of the ligand.

Ultra-low PtCu loading on carbon nanotubes (CNT) catalysts were synthesized by a novel galvanic displacement (GD) method under sonication conditions. The influence of the type of copper template, reaction time, and Pt concentration in the galvanic displacement bath and their correlation to electrocatalytic activity of the catalysts for oxygen reduction reaction in acidic media were studied. Among the catalysts synthesized, the best catalyst identified through electrochemical analysis was used to prepare Membrane Electrode Assembly and evaluated in a hydrogen fuel cell. The maximum power density of the PtCu/CNT and commercial catalyst (20% Pt/C) in the fuel cell were 452 mW cm−2 at 0.424 V and 358 mW cm−2 at 0.475 V, respectively, clearly showing the superior electrocatalytic capability of the PtCu/CNT catalyst synthesized in this study when compared with the commercial catalyst.

Template reaction between 5-methylsalicylaldehyde and 2-hydroxy-1,3-propanediamine in the presence of copper ion led to dinuclear and mononuclear copper(II) complexes [Cu2L(CH3COO)(CH3OH)](CH3OH) (1) and [CuHL](CH3OH) (2), where H3L is N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine. The result of the reactions between 5-methylsalicylaldehyde and 2-hydroxy-1,3-propanediamine in the presence of lanthanide ions and/or copper(II) ion was N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine (H3L B) or [CuHL](CH3OH) (2), respectively. Structures of the compounds were determined by single-crystal X-ray diffraction and physicochemical methods. The microstructures and phase compositions of crystals were studied by scanning electron microscopy (SEM). In dinuclear complex [Cu2L(CH3COO)(CH3OH)](CH3OH) (1), two copper(II) ions are bond to one H3L ligand and one acetate ion. Coordination modes of the two copper centers are different: the geometry of copper 1 is almost ideal square-planar, while that for copper 2 can be described as tetragonal pyramidal. In complex [CuHL](CH3OH) (2), the copper(II) ion is four coordinated and the coordination, rather than square-planar, can be described as flattened tetrahedral. Formation of complexes between copper(II) or lanthanide ions with N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine (H3L) was also studied in solution by pH potentiometry. It should be mentioned that the complexes of lanthanide ions exist only in solution. Additionally, the salen-type ligand H3L and its dinuclear and mononuclear copper(II) complexes were studied by cyclic voltammetry, and their spectroelectrochemical properties were examined.

WOS: 000427932100023, New metalloporphyrazines (MgPz, ZnPz) containing peripheral tetrasubstitutions derived from 7,8-dihydro-6H, 14H, 19H-dibenzo[bj][1,12,5,8]-dioxadithiacyclopentadecine-16,17-dicarbonitrile (6) have been synthesized by a multistep reaction sequence and characterized. Compound 6 has been prepared by the reaction of 1,3-di(2-bromomethyl phenoxy) propane (3) or 1,3-di(2-iodomethylphenoxy) propane (4) which were prepared via bromination or iodination of {2-[3-(2-hydroxymethylphenoxy) propoxy]-phenyl} methanol (2) and cis-1,2-dicyano-1,2-ethylenedithiolate (5). The novel magnesium porphyrazine was prepared by the cyclotetramerization reaction of 6 with magnesium butoxide. The one-step synthesis of porphyrazinato zinc complex has been achieved without a reaction sequence by using dicyano compound (6) and zinc butoxide. The prediction of the geometry optimization, normal mode frequencies, H-1, C-13 NMR, UV absorption spectra, chemical shifts, electronic properties and NBO analysis of the compound were examined by using B3LYP method with a 6-31G(d, p) basis set. These novel compounds were characterized by a combination of elemental analysis, H-1, C-13 NMR, FT-IR, UV-vis and MS spectral data. An X-ray crystal structure of dicarbodinitrile compound (6) was also investigated.

In the family of high-performance cathode materials for lithium-ion batteries, lithium-rich layered oxides come out in front because of a high reversible capacity exceeding 250 mAh g–1. However, the long-term energy retention and high energy densities for lithium-rich layered oxide cathode materials require a stable structure with large surface areas. Here we propose a “bubble template” reaction to build “honeycomb-like” hollow microsphere architecture for a Li1.2Mn0.52Ni0.2Co0.08O2 cathode material. Our material is designed with ca. 8-μm-sized secondary particles with hollow and highly exposed porous structures that promise a large flexible volume to achieve superior structure stability and high rate capability. Our preliminary electrochemical experiments show a high capacity of 287 mAh g–1 at 0.1 C and a capacity retention of 96% after 100 cycles at 1.0 C. Furthermore, the rate capability is superior without any other modifications, reaching 197 mAh g–1 at 3.0 C with a capacity retention of 94% after 10...

Highly electron deficient 6,7-disubstituted (tert-butylsufanyl, 2,6-diisopropylphenoxy, diethylamino, 2-pyridyl, 2-thienyl, 2-furyl) pyrazino[2,3-[Formula: see text]]pyrazino-2,3-dicarbonitriles were prepared and attempted in cyclotetramerization to corresponding tetra(pyrazino[2,3-[Formula: see text]]pyrazino)porphyrazines (TPyzPyzPzs). Only the template reaction in pyridine with zinc acetate and only for the compounds substituted with tert-butylsulfanyl or 2,6-diisopropylphenoxy substituents resulted in efficient cyclotetramerization. Absorption spectra of these zinc TPyzPyzPzs indicated considerable blue shift of the main absorption Q-band ([Formula: see text] 693 nm and 669 nm in pyridine for tert-butylsulfanyl or 2,6-diisopropylphenoxy derivatives) when compared to other aza-analogs of naphthalocyanines. Photophysical parameters ([Formula: see text] [Formula: see text] 0.25, [Formula: see text] [Formula: see text] 0.65) seemed to be unaffected by change of the macrocycle core and only slightly by different peripheral substituents in agreement with heavy-atom effect. Electrochemical data revealed strong electron-deficient character of hetaryl disubstituted pyrazino[2,3-[Formula: see text]]pyrazino-2,3-dicarbonitriles. The first reduction potentials of tert-butylsulfanyl or 2,6-diisopropylphenoxy substituted zinc TPyzPyzPzs were even more cathodically shifted when compared to their corresponding pyrazino[2,3-[Formula: see text]]pyrazino-2,3-dicarbonitriles. TPyzPyzPzs represent an example of the strongest electron-deficient core among the phthalocyanines, naphthalocyanines and their aza-analogs.

The new template reaction between 3-formylchromone-S-methylisothiosemicarbazone and substituted 2-hydroxy benzaldehydes in presence of Ni(OAc)2·4H2O salts afforded four new complexes (1–4) with general molecular formula [NiL1–4] (L1 = (N1-3-formylchromone)(N2-(2-hydroxybenzylidene)-S-methylisothiosemicarbazone, L2 = (N1-3-formylchromone)(N2-(2-hydroxy-1-naphthalene)-S-methylisothiosemicarbazone, L3 = (N1-3-formylchromone)(N2-(5-chloro-2-hydroxybenzylidene)-S-methylisothiosemicarbazone, L4 = (N1-3-formylchromone)(N2-(2-hydroxy-3-methoxybenzylidene)-S-methylisothiosemicarbazone). The compounds are remarkably stable and were obtained in good yields. Structural elucidation was carried out thoroughly in solid and solution-states by elemental analysis and various spectroscopy techniques (IR, UV–Vis, 1H NMR) as well as ESI-mass spectrometry. The molecular structure of the complex 1 was investigated by single-crystal X-ray diffraction. The analysis showed tetradentate coordination of the complexes 1–4, in which the metal atom adopts a square planar geometry with the ligand coordinating ONNO tetradentate fashion and the complex 1 [NiL1] units are forming dimerized chains through Ni(1)⋯Ni(2) interactions (3.408 A). The new complexes were examined for their catalytic performances in one-pot hydroxylation of phenol in presence of H2O2 into catechol and hydroquinone.

Six examples of 2-acetyloxymethyl-substituted 5,6,7-trihydroquinolinyl-8-ylideneamine-nickel(II) chlorides, [2-(CH2OC(O)Me)-8-{N(Ar)}C9H8N]NiCl2 (Ar = 2,6-Me2C6H3 Ni1, 2,6-Et2C6H3 Ni2, 2,6-i-Pr2C6H3 Ni3, 2,4,6-Me3C6H2 Ni4, 2,6-Et2–4-MeC6H2 Ni5, 2,4,6-t-Bu3C6H2 Ni6), have been prepared by a one-pot template reaction of 2-(hydroxymethyl)-6,7-dihydroquinolin-8(5H)-one with nickel dichloride hexahydrate, the corresponding aniline and acetic acid. All complexes were characterized by elemental analysis and IR spectroscopy, while dinuclear Ni2 and mononuclear Ni3·OH2 have additionally been the subject of single crystal X-ray diffraction studies; in both structures the acetyloxymethyl group remained uncoordinated. On activationof Ni1 – Ni6 with MMAO, hexenes (C6: ca. 48% 1-hexene) formed the major product of ethylene oligomerization along with minor quantities of butenes (C4); high overall activities of up to 1.33 × 106 g·mol–1 (Ni)h–1 (for mesityl-containing Ni4) were achieved at 30 oCand 10 atm C2H4. By comparison with MAO as co-catalyst, Ni1 – Ni6 exhibited lower activities but displayed a specificity towards ethylene dimerization (C4: 64–99% 1-butene). Furthermore, sizable induction periods were a feature of the MAO runs with Ni1/MAO reaching peak catalytic activity only after 45 mins.