Reaction of cis-protected [(Me4en)Pd(SO4)] with the newly designed C3-symmetric Ba3L anionic ligand produces a stable trinuclear [(Me4enPd)3L] in a cis-O,O′ mode. A characteristic structural feature is that [(Me4enPd)3L] consists of a total of 10 rings with one 6-membered central benzene ring, three 5-membered rings (PdN2C2), three 6-membered rings (PdO2C3), and three 7-membered rings. This tripalladium(II) complex shows significant multi-center catalytic efficiency in the Heck reaction with the appropriate C3-symmetric trifunctional substrate via geometrical coincident interaction between the substrate and the catalyst. A theoretical calculation of the geometrical intermolecular interaction-behavior between the catalyst ([(Me4enPd)3L]) and the substrate (1,3,5-tris(4-iodophenyl)benzene) in N,N-dimethylformamide solution was carried out.Graphical abstract

Semi-flexible aromatic polycarboxylic acids are gaining impetus in crystal engineering of functional coordination polymers. This work opens up the use of a triphenyl-tricarboxylic acid, 3,5-(4'-carboxylphenyl) benozoic acid (H3cba), as a versatile and still unexplored linker for the synthesis of four new Mn(II), Ni(II), Zn(II), and Cd(II) coordination polymers, formulated as [Mn(μ3-Hcba)(bpy)]n⋅nH2O (1), [Ni(μ-Hcba)(py)(H2O)]n (2), [Zn(μ-Hcba)(phen)(H2O)]n⋅nH2O (3), and [Cd(μ3-Hcba)(bpy)]n⋅nH2O (4). These compounds were prepared via a facile hydrothermal procedure using metal(II) chlorides, H3cba, and supporting N-donor ligands (2,2΄-pyridine, bpy; pyridine, py; 1,10-phenanthroline, phen) acting as crystallization mediators. Compounds 1–4 were fully characterized and their X-ray crystal structures were established, disclosing the metal–organic architectures that range from 1D double chains (1, 4) to 1D chains (2, 3). Thermal and catalytic properties of 1–4 were also investigated. In particular, catalytic potential of the obtained coordination polymers in the Knoevenagel condensation of benzaldehydes with propanedinitrile was evaluated, disclosing an excellent performance of several heterogeneous catalysts with up to 100% product yield.Graphical abstractFour new Mn(II), Ni(II), Zn(II), and Cd(II) 1D coordination polymers have been constructed and the structures and catalytic properties of the polymers were investigated.

To further develop the active site mimics of azadithiolate-bridged [FeFe]-hydrogenases, a series of new diiron azadithiolate complexes [{(μ-SCH2)2N(C6H4CH2CH2OC(O)R)}Fe2(CO)6] (R = CH2C6H4Me-p, 2; C6H5, 3; CH3, 4) bearing bridgehead N-derivation were successfully prepared by facile esterification reaction of parent complex [{(μ-SCH2)2N(C6H4CH2CH2OH)}Fe2(CO)6] (1) and different carboxyl compounds RCO2H in the presence of 4-dimethylaminopyridine (DMAP) as catalyst and dicyclohexylcarbodiimide (DCC) as dehydrating reagent. Complexes 2–4 have been fully characterized by means of elemental analysis, FT-IR and NMR (1H, 13C) spectroscopies, and especially for 2 by X-ray crystallography. Further electrochemical and electrocatalytic properties of target complexes 2–4 and reference analogue 1 were studied and compared in the absence and presence of acetic acid (HOAc) as a proton source by cyclic voltammetry (CV), indicating that they may be considered as the active biomimetic electrocatalysts for proton reduction to hydrogen (H2).

In this study, new 4-chloro-5-(2-isopropyl-5-methylphenoxy)phthalonitrile compound, containing bioactive thymoxy group, and its metal-free phthalocyanine and metallo-phthalocyanine derivatives were synthesized for the first time. Their structures were determined by spectroscopic methods such as FTIR, UV–Vis, 1H-, and 13C-NMR (for phthalonitrile derivative), MALDI-TOF mass spectrometry (for phthalocyanine derivatives) and elemental analysis as well. The phthalocyanines showed excellent solubility in polar and nonpolar solvents without aggregation and absorb at long wavelengths with their high molar coefficient. In N,N-dimethylformamide, the effects of the type of central metal ions [metal-free, indium(III) acetate, lutetium(III) acetate, magnesium(II) or zinc(II)] in the phthalocyanine, containing bioactive thymoxy group, cavity on the spectroscopic, photophysical, and photochemical properties of the phthalocyanines were determined. These features are compared with each other. Lutetium(III) acetate phthalocyanine did not show any fluorescence, while metal-free phthalocyanine and indium(III) acetate phthalocyanine showed low fluorescence. It was determined that magnesium phthalocyanine significantly enriched the fluorescence, and zinc phthalocyanine had appropriate and sufficient fluorescence. Lutetium(III) acetate and zinc(II), especially indium(III) acetate phthalocyanines, could produce large amounts of singlet oxygen. Metal-free and magnesium phthalocyanines had the capacity to produce sufficient singlet oxygen (it means production of enough amount of singlet oxygen by a photosensitizer candidate during PDT applications). All phthalocyanines have sufficient and suitable photostability (it means an ideal photosensitizer should be stable under light irradiation until complete its PDT activation, and it should be decomposed after its PDT activation so that it does not accumulate in the body). With these determined properties, magnesium(II), especially indium(III) acetate and zinc(II) phthalocyanines, may be suitable candidates as type II photosensitizers for photodynamic therapy applications. Lutetium(III) acetate phthalocyanine may be a photosensitizer candidate in photocatalytic applications.

Electrocatalytic water splitting to produce hydrogen is a promising route to provide green hydrogen on a large scale. To explore non-noble metal electrocatalysts with high performance is still a challenge. Herein, a one-step electrodeposition way is developed to construct the heterostructural (NiO-La2O3)/(Ni-La)/NiO/Ni electrocatalysts on Ni foam. The dark Ni-La coating was prepared by co-electrodeposition from an aqueous solution containing LaCl3 and NiCl2 with a molar concentration ratio of 1:5. Among these heterostructural Ni-based electrocatalysts, an excellent HER activity is achieved: an overpotential of 22 mV at the current density of 10 mA cm−2 in 1 M KOH solution. It is demonstrated that the introduction of La significantly reduces the overpotential for HER. The higher the La content in the Ni-La coating of these electrocatalysts, the better the electrocatalytic HER performance was exhibited. This work provides a facile and inexpensive route to prepare Ni-La coating on electrodes in an aqueous solution.

A novel linear tetranuclear Ni(II) complex Ni4L2 {[Ni4L2(H2O)3CH3OH]·CH3OH·2CH3CN·2H2O} was constructed by employing a well-tailored compartmental ligand H4L = (2E,N'E)-N'-(1-(3-((E)-2-hydroxy-3-methoxybenzylideneamino)-2-hydroxyphenyl)ethylidene)-2 -(hydroxyimino)propanehydrazideas with equal equivalent NiCl2·6H2O and NaOH via solvothermal reaction. The complex was well characterized by X-ray crystallography, elemental analysis, infrared emission spectra, UV–visible absorption spectra and thermogravimetry. The crystal structure shows that four nickel ions coordinate with two ligands to form a unique linear structure of Ni4L2. Besides, Ni4L2 act as a catalyst showed good catalytic activity for polymerization of methyl methacrylate (MMA) to obtain PMMA under mild condition.Graphical abstract

The preparation of two cobalt(II) complexes that contain a tridentate ligand with sulfur, nitrogen, and sulfur donor atoms is described. The tridentate ligand precursors are based on bis-imidazole or bis-triazole moieties. The complex based on a bis-imidazole precursor was green in color and was prepared in 93.3% yield. The complex based on a bis-triazole precursor was blue-green in color and was prepared in 69.8% yield. Single-crystal structures of both complexes were obtained. Both complexes contain [BF4]− as the counter-anion. Based on the single-crystal structure, the molecular geometry around the cobalt(II) center is distorted tetrahedral. EPR spectra were obtained for both complexes at 4 K. Each complex has axial symmetry for its electron density and each cobalt(II) complex has S = 3/2. For the complex based on a bis-imidazole precursor, the UV–Vis peaks were observed at 696 nm, 629 nm, 585 (sh) nm, and 375 (sh) nm. For the complex based on bis-triazole, UV–Vis peaks were observed at 681, 613, 570, 243, 239, 236, 233, 230, 227, and 210 nm. Cyclic voltammetry spectra were obtained for both complexes. Both the ligand precursor and the cobalt(II) complexes are redox active. All of the redox waves were irreversible.

In this work, two compounds, namely [Cd2(HL)(4,4′-bpy)(H2O)]n (1), [Cd2(HL)(bpa)(H2O)·2H2O]n (2) (2,3-bis(3,5-dicarboxylphenxoy)benzoic acid (H5L), 4,4′-bipyridine (4,4'-bpy) and 1,2-bi(4-pyridyl)ethane (bpa)), have been synthesized. Complex 1 showed three-dimensional metal–organic framework, which was assembled by carboxylic groups and one type of 4,4′-bpy ligand to layer structure, and further extended by the other type of 4,4′-bpy ligands, while complex 2 displayed 3D metal–organic framework with bpa hanging inside the hole. Fluorescence detection experiment showed that compound 1 can detect nitrofurazone, sulfachlopyridazine and sulfathiazole. In addition, compounds 1 and 2 can be served as luminescent probes for sensing Cu2+ ion.

A novel single-component conductor derived from neutral radical gold bis(dithiolene) complexes is prepared based on the original reactivity of tBuN-substituted 1,3-thiazoline-2-thione heterocycle to give a tBuS-substituted thiazole ring. The corresponding 2-(tert-butylthio)-1,3-thiazole-4,5-dithiolate ligand (tBuS-tzdt) forms the d8 anionic complex [Au(tBuS-tzdt)2]−, easily oxidized through electrocrystallization into the neutral radical [Au(tBuS-tzdt)2]·. The effect of increasingly bulky R groups (R = Et, EtOH, tBu), in the series of such radical complexes [Au(RS-tzdt)2]·, is investigated, with a focus on their solid state organization, either into face-to-face dimers or into non-dimerized, uniform stacks.

By using a multifunctional diarylazooxime ligand LNOH 1, incorporating electron deficient azo chromophore in conjunction with a pendant π-electron-rich naphthyl group, the trans dichloro bis complex of type [CoIII(LNOH)(LNO−)Cl2] 2 has been synthesized. The structure of the chelate has been determined by X-ray crystallography, thereby authenticating the presence of oxime-oximato hydrogen bond within the coordinated moiety. The stability of this complex is attributed to intra-molecular hydrogen bonding as well as due to strong Phπ–Phπ stacking interactions. The complex has been characterized by several spectroscopic techniques, and their electrochemical properties have been reported. These are further complemented by theoretical studies in the form of DFT and TDDFT. The visible excitation for the complex arises from mainly mixed singlet manifold 1ILCT and 1LLCT transitions.Graphical abstract

Two poly-iodine aromatic tricarboxylate complexes: {(Me2NH2)[Mn(TIBTC)(2, 2'-bipy)(H2O)]}n (1) and {(Me2NH2)[Co(TIBTC)(DMA)]}n (2) (DMA = N, N-dimethylacetamide), were designed and synthesized by the hydrothermal synthetic methods (TIBTC = 2, 4, 6-triiodo-1, 3, 5-benzenetricarboxylic acid). Complexes were characterized by microanalysis. The crystal structures of complexes 1 and 2 were determined by X-ray single-crystal diffraction. Complex 1 is a 3D network supramolecular network structure connected by the hydrogen bonds, and complex 2 is a 3D network structure. To explore their functional properties, we first investigated the adsorption capacity of complexes 1 and 2 for iodine capture in cyclohexane solution. The maximum adsorption capacity of complex 2 is 125 mg/g. Meanwhile, the adsorption kinetic curves fitting showed that complexes 1 and 2 all conformed to the pseudo-second-order curves.

One of the most significant sources of copper metal is malachite ore. The world's demand for copper is being positively impacted by increased extraction. However, the chemical compositions of copper in the malachite ore, which vary depending on the region, determine how well copper may be extracted. This study evaluated hydrometallurgical processing of copper metal from malachite ore of Kola Tembein, Tigray, Ethiopia. Malachite ore was processed hydrometallurgical with sulfuric acid to leach copper, which was then recovered using a cementation process of zinc metal. The samples were examined with XRD, EDXRF, SEM, and FAAS. The rock ore sample examined by XRD contained a variety of minerals, including malachite (Cu2CO3(OH)2), quartz (SiO2), albite Ca-rich (CaAl2Si2O8), albite disorder (NaAlSi3O8)m, etc., and the morphology of malachite ore was magnified by SEM. According to the EDXRF results, the malachite ores were dominated by metal oxides of CuO (58.21), SiO2 (19.21), and Fe2O3 (5.32) by weight%. Similar spectroscopic results of malachite were shown for Turkey, China, Chile, and Nigeria malachite. The leaching experiments were optimized by BBD using the RSM to leach and extract malachite at 2.6130 M H2SO4, 133.919 µm particle size, 60 °C, and 600 rpm agitation speed, with 98.159% (68,850 mg/L) copper recovered. Using the cementation process, red–brown copper metal was obtained, and waste determined by AAS having very low concentrations of copper ions (1.74 mg/L) and high concentrations of zinc ions (68,850 mg/L). Both the leaching and cementation are best in environmentally and economically, and further purification will be needed to recover zinc from the waste.

Two Schiff base macrocyclic ligands (L1 and L2) were synthesized using ethylenediamine and terephthalaldehyde (or isophthalaldehyde) as raw materials in acetonitrile solvent. Surprisingly, series of Schiff base macrocyclic ligands with different combination modes (L2-1, L2-2 and L2-3) with isophthalaldehyde as raw material were synthesized. Two Schiff base macrocyclic nickel complexes (Ni-1 and Ni-2) based on L1 and L2 for ethylene oligomerization were obtained with (DME)NiCl2. The synthesized ligands and their corresponding complexes were characterized by various analysis techniques to confirm their chemical structure and thermal stability. And the catalytic properties of the two nickel complexes were also investigated for ethylene oligomerization. When the ethylene pressure was 0.5 MPa, the Al/Ni ratio was 500:1, and the reaction time was 30 min in the presence of MAO, the catalytic activities of Ni-1 and Ni-2 were 4.53 × 104 g/(mol Ni·h) and 4.73 × 104 g/(mol Ni·h), respectively. Compared with PS-Ni complex based on 2,3-butanedione and p-phenylenediamine and three other nickel complexes with simpler ligand structures, Ni-1 and Ni-2 had lower catalytic activities and higher selectivity for C4 olefin because of the higher spatial resistance of the macrocycles.

Three new metal organic frameworks [Zn(bipa)(suc)]n (1), [Ni(bipa)(suc)(H2O)2]n (2) and [Co(bipa)1.5(oip)(H2O)]n (3) (bipa = 2,5-bis(1-imidazole)pyrazine), H2suc = succinic acid, H2oip = 5-hydroxy isophthalic acid) have been synthesized by solvothermal method. They were then characterized by single crystal X-ray diffraction, elemental analysis, infrared spectrum and thermogravimetric analysis. Structural analyses showed that MOFs 1 and 3 exhibited a 3D supramolecular network, while MOF 2 presented a 2D layered structure and was further assembled to a 3D architecture via intermolecular O–H···O hydrogen bond. Moreover, the luminescence sensing of MOF 1 toward nitro explosives was investigated, owing to its excellent chemical stability and luminescence properties. MOF 1 showed remarkable fluorescence quenching toward TNP with a high Ksv value of 6.48 × 104 M−1 and a low limit of detection of 1.4 × 10−5 M. Also, the luminescent sensing mechanism of MOF 1 was investigated.

Two octamolybdate-based complexes formulated by [M2(H2O)4(γ-Mo8O26)(HDIBA)2]·H2O [M = Co (1), Zn (2), DIBA = 3,5-di(1H-imidazol-1-yl)benzoic acid], were synthesized successfully by using hydrothermal method in the presence of 3,5-di(1H-imidazol-1-yl) benzonitrile (DICN) as initial ligand. The DIBA ligand was generated in situ from the hydrolysis of DICN ligand. The γ-octamolybdate polyoxoanion was decorated by two DIBA ligands relying on Mo−O covalent bonds between the carboxyl oxygen atom of DIBA ligand and Mo atom of polyoxoanion. The transition metal centers joined in pairs these modified γ-octamolybdate polyoxoanions into a 1D chain, which were further aggregated to result in a 2D layer. The investigations on the electrochemical performances indicated that the two complexes displayed electrocatalytic and electrochemical sensing activities for bromate and Cr(VI), which provide potential electrode materials in preparing the electrochemical sensors and electrocatalysts.

The structures of new p-cymene Ru(II) complexes with 2-(1-methyl-1H-1,2,4-triazol-3-yl)pyridine and 2-(1-methyl-1H-1,2,4-triazol-5-yl)pyridine were established based on the results of elemental analysis; IR and NMR spectra; and X-ray diffraction studies. Their anticancer activity, tested on human ovarian cancer cell lines A2780 (cisplatin-sensitive) and A2780cis (cisplatin-resistant), is also reported. Graphical abstract

A new set of copper- and zinc-diamine (N-alkylated (L1) and N,N'-dialkylated (L2)) complexes, [Cu(L1)2(NO3)2] (1), [Cu(L1)2(Cl)2].5H2O (2), [Cu(L2)2(NO3)2] (3), [Cu(L2)2(Cl)2] (4), [Zn(L1)2(C2H3O2)2] (5), [Zn(L1)2(Cl)2] (6), [Zn(L2)2(C2H3O2)2] (7), [Zn(L2)2(Cl)2] (8) were prepared by a reaction of the N-alkylated (L1) and N,N'-dialkylated (L2) with their respective copper and zinc salts under mild conditions. The metal complexes were fully characterized by physicochemical and spectroscopic methods. All new metal compounds exhibited significant biological activity against Leishmania amazonensis promastigotes when compared to the free ligands (L1 and L2).

AbstractA novel luminescent coordination polymer (CP) {Mn(H2abtc)(DMF)(H2O)2·2H2O}n (1), (H4abtc = 3,3′,5,5′-azobenzenete-tracarboxylic acid), has been successfully prepared by the solvothermal reaction of H4abtc and MnCl2·4H2O, which has been further characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis (TGA), infrared (IR) spectrum and powder X-ray diffraction (PXRD). 1 can serve as a potential dual response luminescence sensor for picric acid (PA) and CrO42− via luminescence quenching with good selectivity and sensitivity. The quenching behavior of PA toward 1 can be ascribed to the combined effects of electron and resonance energy transfer mechanisms. And the quenching phenomenon of CrO42− to 1 can be explained by the electron transfer mechanism.Graphical abstractA novel luminescent Mn(II)-based coordination polymer 1 has been successfully prepared. 1 can serve as a potential dual response luminescence sensor for Picric acid (PA) and CrO42− with good selectivity and sensitivity.

A series of Zn(II) chlorido complexes (1′–5′) supported by N,N′-bidentate N-(pyridin-2-ylethyl)amine ligands have been synthesized. Zn(II) alkyl and alkoxy complexes 1′-Me–5′-Me and 1′-OBn–5′-OBn were synthesized in situ by first reacting complexes 1′–5′ with methyl lithium and subsequently with benzyl alcohol. Both species 1′-Me–5′-Me and 1′-OBn–5′-OBn showed excellent catalytic activity in ring-opening polymerization (ROP) of cyclic esters with the alkoxyl species performing better. The ROP reactions exhibited pseudo-first-order kinetics with respect to monomer concentration. Polymer molecular weights increased as ligand steric hindrance decreased and they lie between 3096 and 8837 g mol−1 and relatively high molecular weight distributions with dispersity (Ð) values ca. 2 were observed. The poly(rac-lactide) polymers were predominantly heterotactic, while poly(ʟ-lactides) formed were largely isotactic. All polymerization reactions proceeded through coordination insertion mechanism followed by hydrolysis of the metal. Notably, the stereogenic centres of the ligand skeleton influenced control of polymer stereochemistry. Random copolymerization of ε-caprolactone (ε-CL) and lactides (LA) resulted in block gradient copolymers. The sequential addition of lactides after ε-CL gave diblock PCL-b-PLA, and reversing monomer addition did not form any copolymer.Graphical abstract