Nuclease activity of redox/non-redox active binuclear transition metal mixed-polypyridine complexes: [M2(1,4-tpbd)(diimine)2(H2O)2]4+, M = Zn,Co, Ni,Cd, diimine = phen,bpy, dafo

Seven new transition metal complexes formulated as [M₂(1,4-tpbd)(diimine)₂(H₂O)₂]⁴⁺ [M = Zn, Co, Ni, Cd; 1,4-tpbd = N,N,N′,N′-tetrakis(2-pyridylmethyl)benzene-1,4-diamine; diimine is a N,N-donor heterocyclic base like 1,10-phenanthroline (phen), 2,2′-bipyridine (bpy), 4,5-diazafluoren-9-one (dafo)] have been synthesized and structurally characterized by X-ray crystallography: [Zn₂(1,4-tpbd)(phen)₂(H₂O)₂]⁴⁺ (1), [Zn₂(1,4-tpbd)(bpy)₂(H₂O)₂]⁴⁺ (2), [Co₂(1,4-tpbd)(phen)₂(H₂O)₂]⁴⁺ (3), [Ni₂(1,4-tpbd)(phen)₂(H₂O)₂]⁴⁺ (4), [Ni₂(1,4-tpbd)(bpy)₂(H₂O)₂]⁴⁺ (5), [Ni₂(1,4-tpbd)(dafo)₂(H₂O)₂]⁴⁺ (6) and [Cd₂(1,4-tpbd)(phen)₂(H₂O)₂]⁴⁺ (7). Single crystal diffraction reveals that the metals in the complexes are all in a distorted octahedral geometry. The interactions of the seven complexes with calf thymus DNA (CT-DNA) have been investigated by UV absorption, fluorescence, circular dichroism spectroscopy and viscosity measurements. The apparent binding constants (K_app) are calculated to be 5.2?×?10⁵ M^?1 for 1, 1.05?×?10⁵ M^?1 for 2, 5.76?×?10⁵ M^?1 for 3, 4.57?×?10⁵ M^?1 for 4, 1.29?×?10⁵ M^?1 for 5, 1.7?×?10⁵ M^?1 for 6, 2.53?×?10⁵ M^?1 for 7, the binding propensity to the calf thymus DNA in the order: 3 (Co-phen) > 1 (Zn-phen) > 4 (Ni-phen) > 7 (Cd-phen) > 6 (Ni-dafo) > 5 (Ni-bpy) > 2 (Zn-bpy). Furthermore, these complexes display efficient oxidative cleavage of supercoiled DNA; the Zn(II)/H₂O₂ and Cd(II)/H₂O₂ systems efficiently cleave DNA attributed to the peroxide ion coordinated to the Zn(II) and Cd(II), which enhanced their nucleophilicity, this is rare.     

Structure and cytotoxicity of zinc (II) and cobalt (II) complexes based on 1,3,5‐tris(1‐imidazolyl) benzene

Three novel complexes, [Zn (tib)₂·(H₂O)₂]·(NO₃)₂ ( 1 ), [Co (tib)₂]·2NO₃ ( 2 ) and [Co₂(tib)₂(btc)]·H₂O ( 3 ) [H₄btc = 1,2,4,5‐benzenetetracarboxylic acid; H₂tib = 1,3,5‐tris(1‐imidazolyl)benzene], were synthesized and characterized by single‐crystal X‐ray, IR and elemental analysis. The interaction of these complexes with FS‐DNA (fish sperm DNA) was monitored, and binding constants were determined using UV/Vis, which revealed that they have the ability to bind to FS‐DNA. DNA‐binding constants (K) for the three complexes were 2.2 × 10⁴ m ^?1, 0.7 × 10⁴ m ^?1 and 0.09 × 10⁴ m ^?1, respectively. The interaction capacity of the complexes with FS‐DNA has been investigated by fluorescence spectroscopy. Stern–Volmer quenching plot values for complexes 1 , 2 and 3 were 0.3784, 0.1028 and 0.076, respectively. The viscosity measurement suggested that complexes 1 , 2 and 3 interact with DNA in an intercalation mode. In addition, anti‐cancer activities of these complexes investigated through MTT assays in vitro indicated that the complexes showed good cytotoxic activity against cancer cell lines. Cytotoxic activity of test complexes against two different cancer cell lines (HeLa and KB cells) showed significant cancer cell inhibition rates. Flow cytometry experiments and morphological apoptosis studies showed that the complexes induced apoptosis of HeLa tumor cell lines. Finally, a further molecular docking technique was employed to confirm the binding of the complexes toward the molecular target DNA.     

4, 5-二氮芴-9-酮Cu(II)、Co(II)多核配合物的合成，晶体结构及DNA结合作用初探

合成了两个4, 5-二氮芴-9-酮Cu(II)、Co(II)的多核配合物[Cu2(CH3COO)4(H2O) 2]·2dafo 1 和 [(μ2-O)2-Co3(dafo)6] (ClO3)2·H2O 2 (dafo=4,5-diazafluoren-9-one) 并且对它们进行了元素分析,红外以及紫外光谱的表征,同时测定了配合物的晶体结构。用紫外光谱,发射光谱和循环伏安三种方法初步研究了配合物1和2与DNA的结合作用,结果表明,配合物1和2与DNA的结合为以插入作用为主 。     

Synthesis,Characterization, and DNA Interaction Studies of the Ruthenium(II) Complexes [Ru(bpy)2(ipbp)]2+ and [Ru(ipbp)(phen)2]2+ (ipbp=3‐(1H‐Imidazo[4,5‐f][1,10]phenanthrolin‐2‐yl)‐4H‐1‐benzopyran‐2‐one; bpy=2,2′‐Bipyridine; phen=1,10‐Phenanthroline)

A novel ligand 3‐(1H‐imidazo[4,5‐f][1,10]phenanthrolin‐2‐yl)‐4H‐1‐benzopyran‐4‐one (ipbp) and its ruthenium(II) complexes [Ru(bpy)₂(ipbp)]²⁺ ( 1 ) and [Ru(ipbp)(phen)₂]²⁺ ( 2 ) (bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis and mass, ¹H‐NMR, and electronic‐absorption spectroscopy. The electrochemical behavior of the complexes was studied by cyclic voltammetry. The DNA‐binding behavior of the complexes was investigated by spectroscopic methods and viscosity measurements. The results indicate that complexes 1 and 2 bind with calf‐thymus DNA in an intercalative mode. In addition, 1 and 2 promote cleavage of plasmid pBR 322 DNA from the supercoil form I to the open circular form II upon irradiation.     

Hydrogen‐bonding and π–π stacking interactions in aquachloridobis(1,10‐phenanthroline)cobalt(II) chloride dichloridobis(1,10‐phenanthroline)cobalt(II) hexahydrate

The title compound, [CoCl(C₁₂H₈N₂)₂(H₂O)]Cl·[CoCl₂(C₁₂H₈N₂)₂]·6H₂O, is the first example of a new 1:1 cocrystal of the octahedral [CoCl₂(phen)₂] and [CoCl(phen)₂(H₂O)]⁺·Cl⁻ complexes (phen is 1,10‐phenanthroline). The latter form heterochiral dimers held by strong π–π stacking interactions via their phenathroline ligands, which confirms that π stacking is an important and reliable synthon in supramolecular design. In addition, the crystal structure is networked by H₂O...H₂O, H₂O...Cl⁻ and H₂O...Cl hydrogen bonds, which interconnect the different units of the cobalt complexes.     

Two nickel(II) bis[(pyridin‐2‐yl)methyl]amine complexes with homophthalic and benzene‐1,2,4,5‐tetracarboxylic acids

Two new Ni^II complexes involving the ancillary ligand bis[(pyridin‐2‐yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2‐(2‐carboxylatophenyl)acetate] and benzene‐1,2,4,5‐tetracarboxylate (btc), namely catena‐poly[[aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)]‐μ‐2‐(2‐carboxylatophenyl)aceteto‐κ²O:O′], [Ni(C₉H₆O₄)(C₁₂H₁₃N₃)(H₂O)]_n, and (μ‐benzene‐1,2,4,5‐tetracarboxylato‐κ⁴O¹,O²:O⁴,O⁵)bis(aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) bis(triaqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) benzene‐1,2,4,5‐tetracarboxylate hexahydrate, [Ni₂(C₁₀H₂O₈)(C₁₂H₁₃N₃)₂(H₂O)₂]·[Ni(C₁₂H₁₃N₃)(H₂O)₃]₂(C₁₀H₂O₈)·6H₂O, (II), are presented. Compound (I) is a one‐dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent Ni^II centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H₂O)]₂(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H₂O)₃]²⁺ cations which (in a 2:1 ratio) provide charge balance for btc⁴⁻ anions. A profuse hydrogen‐bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.     

Killing two birds with one stone: 2D+2D→3D parallel stacking and 3D self‐penetrating structures in one reaction and their crystal‐to‐crystal transformation

Reaction of the flexible phenolic carboxylate ligand 2‐(3,5‐dicarboxylbenzyloxy)benzoic acid (H₃L) with nickel salts in the presence of 1,2‐bis(pyridin‐4‐yl)ethylene (bpe) leads to the generation of a mixture of the two complexes under solvolthermal conditions, namely poly[[aqua[μ‐1,2‐bis(pyridin‐4‐yl)ethylene‐κ²N:N′]{μ‐5‐[(2‐carboxyphenoxy)methyl]benzene‐1,3‐dicarboxylato‐κ³O¹,O^1′:O³}nickel(II)] dimethylformamide hemisolvate monohydrate], {[Ni(C₁₆H₁₀O₇)(C₁₂H₁₀N₂)(H₂O)]·0.5C₃H₇NO·H₂O}_n or {[Ni(HL)(bpe)(H₂O)]·0.5DMF·H₂O}_n, 1 , and poly[[diaquatris[μ‐1,2‐bis(pyridin‐4‐yl)ethylene‐κ²N:N′]bis{μ‐5‐[(2‐carboxyphenoxy)methyl]benzene‐1,3‐dicarboxylato‐κ²O¹:O⁵}nickel(II)] dimethylformamide disolvate hexahydrate], {[Ni₂(C₁₆H₁₀O₇)₂(C₁₂H₁₀N₂)₃(H₂O)₂]·2C₃H₇NO·6H₂O}_n or {[Ni₂(HL)₂(bpe)₃(H₂O)₂]·2DMF·6H₂O}_n, 2 . In complex 1 , the Ni^II centres are connected by the carboxylate and bpe ligands to form two‐dimensional (2D) 4‐connected (4,4) layers, which are extended into a 2D+2D→3D (3D is three‐dimensional) supramolecular framework. In complex 2 , bpe ligands connect to Ni^II centres to form 2D layers with Ni₆(bpe)₆ metallmacrocycles. Interestingly, 2D+2D→3D inclined polycatenation was observed between these layers. The final 5‐connected 3D self‐penetrating structure was generated through further connection of Ni–carboxylate chains with these inclined motifs. Both complexes were fully characterized by single‐crystal analysis, powder X‐ray diffraction analysis, FT–IR spectra, elemental analyses, thermal analysis and UV–Vis spectra. Notably, an interesting metal/ligand‐induced crystal‐to‐crystal transformation was observed between the two complexes.     

Ligand Substitution Reactions on Aquapentachloro‐ and Hexachloroplatinic Acid — Synthesis and Characterization of Tetrachloroplatinum(IV) Complexes with Heterocyclic N,N Donors

Reactions of aquapentachloroplatinic acid, (H₃O)[PtCl₅(H₂O)]·2(18C6)·6H₂O ( 1 ) (18C6 = 18‐crown‐6), and H₂[PtCl₆]·6H₂O ( 2 ) with heterocyclic N, N donors (2, 2′‐bipyridine, bpy; 4, 4′‐di‐tert‐butyl‐2, 2′‐bipyridine, tBu₂bpy; 1, 10‐phenanthroline, phen; 4, 7‐diphenyl‐1, 10‐phenanthroline, Ph₂phen; 2, 2′‐bipyrimidine, bpym) afforded with ligand substitution platinum(IV) complexes [PtCl₄(N∩N)] (N∩N = bpy, 3a ; tBu₂bpy, 3b ; Ph₂phen, 5 ; bpym, 7 ) and/or with protonation of N, N donor yielding (R₂phenH)₂[PtCl₆] (R = H, 4a ; Ph, 4b ) and (bpymH)⁺ ( 8 ). With UV irradiation Ph₂phen and bpym reacted with reduction yielding platinum(II) complexes [PtCl₂(N∩N)] (N∩N = Ph₂phen, 6 ; bpym, 9 ). Identities of all complexes were established by microanalysis as well as by NMR (¹H, ¹³C, ¹⁹⁵Pt) and IR spectroscopic investigations. Molecular structures of [PtCl₄(bpym)]·MeOH ( 7 ) and [PtCl₂(Ph₂phen)] ( 6 ) were determined by X‐ray diffraction analyses. Differences in reactivity of bpy/bpym and phen ligands are discussed in terms of calculated structures of complexes [PtCl₅(N∩N)]^— with monodentately bound N, N ligands (N∩N = bpy, 10a ; phen, 10b ; bpym, 10c ).     

Synthesis,DNA‐Binding and Photocleavage Studies of the Ruthenium(II) Complexes [Ru(phen)2(ppd)]2+ and [Ru(phen)(ppd)2]2+ (ppd=Pteridino[6,7‐f] [1,10]phenanthroline‐11,13(10H,12H)‐dione,phen=1,10‐Phenanthroline)

Two new complexes, [Ru(phen)₂(ppd)]²⁺ ( 1 ) and [Ru(phen)(ppd)₂]²⁺ ( 2 ) (ppd=pteridino[6,7‐f] [1,10]phenanthroline‐11,13(10H,12H)‐dione, phen=1,10‐phenanthroline) were synthesized and characterized by ES‐MS, ¹H‐NMR spectroscopy, and elemental analysis. The intercalative DNA‐binding properties of 1 and 2 were investigated by absorption‐spectroscopy titration, luminescence‐spectroscopy studies, thermal denaturation, and viscosity measurements. The theoretical aspects were further discussed by comparative studies of 1 and 2 by means of DFT calculations and molecular‐orbital theory. Photoactivated cleavage of pBR322 DNA by the two complexes were also studied, and 2 was found to be a much better photocleavage reagent than 1 . The mechanism studies revealed that singlet oxygen and the excited‐states redox potentials of the complex may play an important role in the DNA photocleavage.     

Structural diversity,magnetic properties and luminescence of NiII,CoII and ZnII coordination polymers derived from 3,3′‐[(5‐carboxy‐1,3‐phenylene)bis(oxy)]dibenzoic acid and 1,10‐phenanthroline

Three novel coordination polymers (CPs), namely poly[[di‐μ‐aqua‐bis{μ₄‐3,3′‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoato‐κ⁵O¹:O^1′,O³:O⁵:O^5′}bis(1,10‐phenanthroline‐κ²N,N′)trinickel(II)] dimethylformamide 1.5‐solvate trihydrate], {[Ni₃(C₂₁H₁₁O₈)₂(C₁₂H₈N₂)₂(H₂O)₂]·1.5C₃H₇NO·3H₂O}_n, (I), poly[[di‐μ‐aqua‐bis{μ₄‐3,3′‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoato‐κ⁵O¹:O^1′,O³:O⁵:O^5′}bis(1,10‐phenanthroline‐κ²N,N′)tricobalt(II)] diethylamine disolvate tetrahydrate], {[Co₃(C₂₁H₁₁O₈)₂(C₁₂H₈N₂)₂(H₂O)₂]·2C₂H₇N·4H₂O}_n, (II), and catena‐poly[[aqua(1,10‐phenanthroline‐κ²N,N′)zinc(II)]‐μ‐5‐(3‐carboxyphenoxy)‐3,3′‐oxydibenzoato‐κ²O¹:O³], [Zn(C₂₁H₁₂O₈)(C₁₂H₈N₂)(H₂O)]_n, (III), have been synthesized by the reaction of different metal ions (Ni²⁺, Co²⁺ and Zn²⁺), 3,3′‐[(5‐carboxy‐1,3‐phenylbis(oxy)]dibenzoic acid (H₃cpboda) and 1,10‐phenanthroline (phen) under solvothermal conditions. All the CPs were characterized by elemental analysis, single‐crystal and powder X‐ray diffraction, FT–IR spectroscopy and thermogravimetric analysis. Complexes (I) and (II) have isomorphous structures, featuring similar linear trinuclear structural units, in which the central Ni^II/Co^II atom is located on an inversion centre with a slightly distorted octahedral [NiO₆]/[CoO₆] geometry. This comprises four carboxylate O‐atom donors from two cpboda^3? ligands and two O‐atom donors from bridging water molecules. The terminal Ni^II/Co^II groups are each connected to the central Ni^II/Co^II cation through two μ_1,3‐carboxylate groups from two cpboda^3? ligands and one water bridge, giving rise to linear trinuclear [M₃(μ₂‐H₂O)₂(RCOO)₄] (M = Ni²⁺/Co²⁺) secondary building units (SBUs) and the SBUs develop two‐dimensional‐networks parallel to the (100) plane via cpboda^3? ligands with new (3²·4)₂(3²·8³·9)₂(3⁴·4².8²·9⁴·10³) topological structures. Zinc complex (III) displays one‐dimensional coordination chains and the five‐coordinated Zn atom forms a distorted square‐pyramidal [ZnO₃N₂] geometry, which is completed by two carboxylate O‐atom donors from two distinct Hcpboda^2? ligands, one O atom from H₂O and two N atoms from a chelating phen ligand. Magnetically, CP (I) shows weak ferromagnetic interactions involving the carboxylate groups, and bridging water molecules between the nickel(II) ions, and CP (II) shows antiferromagnetic interactions between the Co²⁺ ions. The solid‐state luminescence properties of CP (III) were examined at ambient temperature and the luminescence sensing of Cr₂O₇^2?/CrO₄^2? anions in aqueous solution for (III) has also been investigated.     

Experimental and Theoretical Studies on DNA‐Binding and Spectral Properties of ‘Light Switch’ Complexes [Ru(L)2(ppn)]2+ (L=2,2′‐Bipyridine and 1,10‐Phenanthroline; ppn=Pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine)

The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its Ru^II complexes [Ru(bpy)₂(ppn)]²⁺ ( 1 ; bpy=2,2′‐bipyridine) and [Ru(phen)₂(ppn)]²⁺ ( 2 ; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, ¹H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants K_b of (1.7±0.4)?10⁶ M ^?1 and (2.6±0.2)?10⁶ M ^?1, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)₂(ppn)]²⁺( 2 ) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2 , theoretical calculations were also carried out applying the DFT/TDDFT method.     

Three different bonding modes of cyano groups in the coordination polymer [Cu(en)2(H2O)][Cu(en)2Ni2Cu2(CN)10]·2H2O (en is 1,2‐diaminoethane)

Partial reduction of the Cu^II ions in the aqueous system Cu^II–en–[Ni(CN)₄]^2? (1/1/1) (en is 1,2‐di­amino­ethane) yields a novel heterobimetallic mixed‐valence compound, poly­[[aqua­bis(1,2‐di­amino­ethane)copper(II)] [hexa‐μ‐cyano‐tetra­cyano­bis(1,2‐di­amino­ethane)­tricopper(I,II)­dinickel(II)] dihydrate], [Cu(C₂H₈N₂)₂(H₂O)][Ni₂Cu₃(CN)₁₀(C₂H₈N₂)₂]·2H₂O or [Cu(en)₂(H₂O)][Cu(en)₂Ni₂Cu₂(CN)₁₀]·2H₂O. The structure is formed by a negatively charged two‐dimensional array of the cyano complex [Cu(en)₂Ni₂Cu₂(CN)₁₀]_n^2n?, [Cu(en)₂(H₂O)]²⁺ complex cations and water mol­ecules of crystallization. These last are involved in a complicated hydrogen‐bonding system. The cyano groups act as terminal, μ₂‐bridging or μ₃‐bridging ligands.     

A thermally stable three‐dimensional cobalt(II) coordination polymer based on the V‐shaped ligand 4‐(4‐carboxyphenoxy)isophthalate

A new cobalt(II) coordination polymer (CP), poly[[bis[μ₆‐4‐(4‐carboxylatophenoxy)benzene‐1,3‐dicarboxylato‐κ⁶O¹:O¹:O³:O^3′:O⁴:O^4′]bis(1,10‐phenanthroline‐κ²N,N′)tricobalt(II)] 0.72‐hydrate], {[Co₃(C₁₅H₇O₇)₂(C₁₂H₈N₂)₂]·0.72H₂O}_n, (I), is constructed from Co^II ions and 4‐(4‐carboxyphenoxy)isophthalate (cpoia³⁻) and 1,10‐phenanthroline (phen) ligands. Based on centrosymmetric trinuclear [Co₃(phen)₂(COO)₆] secondary building units (SBUs), the structure of (I) is a three‐dimensional CP with a (3,6)‐connected net and point symbol (4².6)₂(4⁴.6².8⁷.10²). The positions of four [Co₃(phen)₂(COO)₆] SBUs and four cpoia³⁻ ligands reproduce a Chinese‐knot‐shaped arrangement along the ab plane. (I) has been characterized by single‐crystal X‐ray diffraction, IR spectroscopy, powder X‐ray diffraction (PXRD) and thermostability analysis. It shows a good thermal stability from room temperature to 673 K. In addition, the temperature dependence of the magnetic properties was measured.     

Metal–Organic Frameworks Containing Missing‐Linker Defects Leading to High Hydroxide‐Ion Conductivity

The ionic conductivity properties of the face‐centered cubic [Ni₈(OH)₄(H₂O)₂(BDP_X)₆] (H₂BDP_X=1,4‐bis(pyrazol‐4‐yl)benzene‐4‐X with X=H ( 1 ), OH ( 2 ), NH₂ ( 3 )) metal–organic framework (MOF) systems as well as their post‐synthetically modified materials K[Ni₈(OH)₅(EtO)(BDP_X)_5.5] ( 1@KOH , 3@KOH ) and K₃[Ni₈(OH)₃(EtO)(BDP_O)₅] ( 2@KOH ), which contain missing‐linker defects, have been studied by variable temperature AC impedance spectroscopy. It should be noted that these modified materials exhibit up to four orders of magnitude increase in conductivity ^‐values in comparison to pristine 1 – 3 systems. As an example, the conductivity value of 5.86×10^?9 S cm^?1 (activation energy E_a of 0.60 eV) for 2 at 313 K and 22 % relative humidity (RH) increases up to 2.75×10^?5 S cm^?1 (E_a of 0.40 eV) for 2@KOH . Moreover, a further increase of conductivity values up to 1.16×10^?2 S cm^?1 and diminution of E_a down to 0.20 eV is achieved at 100 % RH for 2@KOH . The increased porosity, basicity and hydrophilicity of the 1@KOH – 3@KOH materials compared to the pristine 1 – 3 systems should explain the better performance of the KOH‐modified materials.     

Conformational Effects of [Ni2(μ‐ArS)2] Cores on Their Electrocatalytic Activity

Two nickel complexes supported by tridentate NS₂ ligands, [Ni₂(κ‐N,S,S,S′‐N^Ph{CH₂(MeC₆H₂R′)S}₂)₂] ( 1 ; R′=3,5‐(CF₃)₂C₆H₃) and [Ni₂(κ‐N,S,S,S′‐N^iBu{CH₂C₆H₄S}₂)₂] ( 2 ), were prepared as bioinspired models of the active site of [NiFe] hydrogenases. The solid‐state structure of 1 reveals that the [Ni₂(μ‐ArS)₂] core is bent, with the planes of the nickel centers at a hinge angle of 81.3(5)°, whereas 2 shows a coplanar arrangement between both nickel(II) ions in the dimeric structure. Complex 1 electrocatalyzes proton reduction from CF₃COOH at ?1.93 (overpotential of 1.04 V, with i_cat/i_p≈21.8) and ?1.47 V (overpotential of 580 mV, with i_cat/i_p≈5.9) versus the ferrocene/ferrocenium redox couple. The electrochemical behavior of 1 relative to that of 2 may be related to the bent [Ni₂(μ‐ArS)₂] core, which allows proximity of the two Ni???Ni centers at 2.730(8) Å; thus possibly favoring H⁺ reduction. In contrast, the planar [Ni₂(μ‐ArS)₂] core of 2 results in a Ni???Ni distance of 3.364(4) Å and is unstable in the presence of acid.     

Crystal structure,shape analysis and bioactivity of new LiI,NaI and MgII complexes with 1,10‐phenanthroline and 2‐(3,4‐dichlorophenyl)acetic acid

Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with M_n(CO₃) (M = Li^I, Na^I and Mg^II; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)lithium(I), [Li(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)] or [Li(dca)(phen)(H₂O)] ( 1 ), the dinuclear sodium complex di‐μ‐aqua‐bis{[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)sodium(I)}, [Na₂(C₈H₅Cl₂O₂)₂(C₁₂H₈N₂)₂(H₂O)₂] or [Na₂(dca)₂(phen)₂(H₂O)₂] ( 2 ), and the one‐dimensional chain magnesium complex catena‐poly[[[diaqua(1,10‐phenanthroline‐κ²N,N′)magnesium]‐μ‐2‐(3,4‐dichlorophenyl)acetato‐κ²O:O′] 2‐(3,4‐dichlorophenyl)acetate monohydrate], {[Mg(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)₂](C₈H₅Cl₂O₂)·H₂O}_n or {[Mg(dca)(phen)(H₂O)₂](dca)·H₂O}_n ( 3 ). In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca^? ligands coordinate either in a monodentate (in 1 and 2 ) or bidentate (in 3 ) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P with one molecule in the asymmetric unit. The Li⁺ ion adopts a four‐coordinated distorted seesaw geometry comprising an [N₂O₂] donor set. Complex 2 crystallizes in the triclinic space group P with half a molecule in the asymmetric unit, in which the Na⁺ ion adopts a five‐coordinated distorted spherical square‐pyramidal geometry, with an [N₂O₃] donor set. Complex 3 crystallizes in the orthorhombic space group P2₁2₁2₁, with one Mg²⁺ ion, one phen ligand, two dca^? ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca^? anion is not coordinated, whereas the second dca^? anion coordinates in a bidentate fashion bridging two Mg²⁺ ions, resulting in a one‐dimensional chain structure for 3 . The Mg²⁺ ion adopts a distorted octahedral geometry, with an [N₂O₄] donor set. Complexes 1 – 3 were evaluated against urease and α‐glucosidase enzymes for their inhibition potential and were found to be inactive.     

Synthesis and Structural Characterization of the Helical Coordination Polymers [Co(phen)(oba)(H2O)2] and [Cd3(phen)3(oba)2(Hoba)2(H2O)2] (phen = 1, 10‐phenanthroline; oba = 4, 4′‐oxybis(benzoate)

Two coordination polymers, [Co(phen)(oba)(H₂O)₂] ( 1 ) and [Cd₃(phen)₃(oba)₂(Hoba)₂(H₂O)₂] ( 2 ) (oba = 4, 4′‐oxybis(benzoate), phen = 1, 10‐phenanthroline) have been synthesized under hydrothermal conditions. Complex 1 crystallizes in monoclinic, P2₁/n, a = 7.543(6), b = 33.05(2), c = 9.902(5)Å, β = 103.69(2)°, V = 2398(3)ų, Z = 4; 2 in monoclinic, P2/n, a = 15.11(1), b = 10.069(8), c = 28.02(2)Å, β = 101.83(1)°, V = 4174(5)ų, Z = 2. X‐ray single‐crystal diffraction investigations shows that the complexes 1 and 2 consist of helical chains, which are further assembled into layers and networks via supramolecular interactions such as π—π stacking interactions and hydrogen bonds, respectively. The results indicate that the coordination environment is one of the most important factors for assembly of single‐stranded helical chains into double‐stranded helical chains via supramolecular interactions.     

[N,N′‐Bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminato]­nickel(II) and [N,N′‐bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminato]copper(II)

In the title compounds, {2,2′‐[2,2‐di­methyl‐1,3‐propane­diyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴N,N′,O,O′}nickel(II), [Ni(C₁₉H₂₀N₂O₂)], and {2,2′‐[2,2‐di­methyl‐1,3‐propane­diyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴N,N′,O,O′}copper(II), [Cu(C₁₉H₂₀N₂O₂)], the Ni^II and Cu^II atoms are coordinated by two iminic N and two phenolic O atoms of the N,N′‐bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminate (SALPD^2?, C₁₇H₁₆N₂O₂^2?) ligand. The geometry of the coordination sphere is planar in the case of the Ni^II complex and distorted towards tetrahedral for the Cu^II complex. Both complexes have a cis configuration imposed by the chelate ligand. The dihedral angles between the N/Ni/O and N/Cu/O coordination planes are 17.20 (6) and 35.13 (7)°, respectively.     

Synthesis and Structural Characterization of a Binuclear Mixed‐Ligand (Salicylate and N,N‐diethylnicotinamide) Nickel(II) Complex,Its Magnetic Properties. [Ni2(µ‐Sal)4(Dena)2]H2O

The title complex of [Ni₂(µ‐Sal)₄(Dena)₂]H₂O, [( µ‐tetrakissalicylato‐κ‐O,O)(bis‐N,N‐diethylnicotinamide‐κ‐N)(binickel(II))]hydrate, C₄₈H₅₂Ni₂N₄O₁₆, has been synthesized and explained as structural using some elemental analysis, FT‐IR spectra, UV‐Vis reflectance, magnetic measurements, thermal analysis and x‐ray diffraction methods. The analysis results showed that the unit cell of complex includes two molecules Ni^II cation, four molecules salicylates as bridge and two molecules N,N‐diethylnicotinamide ligands, also there is one molecule hydrated aqua. The compound crystallizes in the monoclinic space group P2₁/c with the following unit‐cell parameters: a =13.6776(6) Å, b =10.5238(3) Å, c =21.8165(9), α=90.00°, β=126.546(3)°, γ=90.00º and Z=2. The compound [Ni₂(µ‐Sal)₄(Dena)₂]H₂O is a typical paddle‐wheel complex structure. Two Ni^II ions are bridged by four salicylate ligands (O2, O2ⁱ, O3, O3ⁱ, O5, O5ⁱ, O6 and O6ⁱ) using a µ‐COO^? coordination mode [symmetry code: (i) 1‐x, 1‐y, 1‐z]. Each Ni^II also coordinates to one nitrogen atom (N1 and N1ⁱ) from one N,N‐diethylnicotinamide ligand molecule in the axial position. The complex has strong paramagnetic properties.     

Synthesis,Crystal Structures and Properties of Tetrametallic Complexes: [M2(phen)4(FCA)2](ClO4)2·(H2O)2 (M=Zn or Co,phen=1,10‐phenanthroline,FCA=anion of 3‐ferrocenyl‐2‐crotonic acid)

Two new complexes [Zn₂(phen)₄(FCA)₂](ClO₄)₂·(H₂O)₂ ( 1 ) and [Co₂(phen)₄ (FCA)₂](ClO₄)₂·(H₂O)₂ (2) (FCA=anion of 3‐ferrocenyl‐2‐crotonic acid, phen=1,10‐phenanthroline) have been synthesized, and characterized by elemental analysis, IR, UV‐Vis spectra, thermal analyses, and single‐crystal X‐ray diffraction. Two M(II) (M=Zn or Co) ions are bridged by two FCA anions with syn‐anti bridging ligands, leading to dimeric cores, [M₂(phen)₄(FCA)₂]²⁺, and each M(II) ion is six‐coordinated in a distorted octahedral geometry by two chelate phen ligands and two μ₂‐carboxylate oxygen atoms from two FCA groups. The M(II)…M(II) intradimer distances are 0.4391 and 0.4462 nm in 1 and 2 , respectively. Electrochemical properties of the complexes have been discussed.