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Four mononuclear bioefficient zinc coordination complexes [Zn(NN)3](ClO4)2 (A–D) involving chiral bidentate Schiff base ligands have been synthesized and characterized by IR, 1H, and 13C NMR spectroscopy and mass spectrometry. X-ray crystal structures of three of the zinc complexes revealed that the zinc metal ion is hexacoordinated, exhibiting a distorted octahedral geometry where both the nitrogen atoms (NN = pyridyl and imine) of imines are coordinated to the central zinc ion. The isolated zinc complexes were evaluated for their antimicrobial activity in vitro against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, displaying varying levels of growth inhibition. An acute toxicity test conducted using Artemia salina and Swiss albino mice showed that the zinc complexes A–D were non-toxic towards A. salina at concentrations below 414, 564, 350, and 385 µM, respectively, and did not affect liver biochemical parameters, although pyknosis was induced in hepatocytes of the treated mice. [ABSTRACT FROM AUTHOR]

During the last years, there has been an increased effort in the discovery of selective and potent kinase inhibitors for targeted cancer therapy. Kinase inhibitors exhibit less toxicity compared to conventional chemotherapy, and several have entered the market. Mirk/Dyrk1B kinase is a promising pharmacological target in cancer since it is overexpressed in many tumors, and its overexpression is correlated with patients' poor prognosis. Mirk/Dyrk1B acts as a negative cell cycle regulator, maintaining the survival of quiescent cancer cells and conferring their resistance to chemotherapies. Many studies have demonstrated the valuable therapeutic effect of Mirk/Dyrk1B inhibitors in cancer cell lines, mouse xenografts, and patient-derived 3D-organoids, providing a perspective for entering clinical trials. Since the majority of Mirk/Dyrk1B inhibitors target the highly conserved ATP-binding site, they exhibit off-target effects with other kinases, especially with the highly similar Dyrk1A. In this review, apart from summarizing the data establishing Dyrk1B as a therapeutic target in cancer, we highlight the most potent Mirk/Dyrk1B inhibitors recently reported. We also discuss the limitations and perspectives for the structure-based design of Mirk/Dyrk1B potent and highly selective inhibitors based on the accumulated structural data of Dyrk1A and the recent crystal structure of Dyrk1B with AZ191 inhibitor. [ABSTRACT FROM AUTHOR]

In the present work, novel polymeric copper(II) coordination compounds, namely [Cu2(cpida)(H2O)4][Cu(cpida)]·3H2O (1) (cpida3− = 2-(carboxyphenyl)iminodiacetate anion) and Na[Cu(cpida)] (3), were synthesized and characterized using infrared spectroscopy, thermogravimetric analysis, elemental analysis, and single-crystal X-ray diffraction. Compound 1 was obtained by slowly evaporating an aqueous solution of H3cpida, copper(II) sulfate, and NaOH at room temperature. The structural characterization revealed that 1 is an ionic entity formed by the [Cu(cpida)]− anion and the [Cu2(cpida)(H2O)4]+ cation, both of polymeric 1D structure. Compound 3 was prepared under similar conditions from copper perchlorate and crystallized via acetone diffusion. It is a coordination polymer formed by the [Cu(cpida)]− units, and the sodium cation is present in the structure, counterbalancing the anion charge. Depending on the crystallization conditions, it was possible to obtain other solvation forms of these structures. Starting from the conditions of compound 1, via the diffusion of ethanol, [Cu2(cpida)(H2O)4][Cu(cpida)]·H2O·1/2EtOH (2) was precipitated, while a hydrate form of compound 3 with the formula Na[Cu(cpida)]·2H2O (4) was obtained via methanol diffusion. [ABSTRACT FROM AUTHOR]

[Display omitted] An unusual neutral dinuclear palladium(II) complex with two head-to-head orientated μ- P , S -bridging ligands was obtained by the reaction of Pd(MeCN) 2 Cl 2 with (1 R ,5 R)-3-(4-phenylthiobutoxy)-2,4-diphenyl-2,4-diaza-3-phospha-bicyclo[3.4.0]nonane. The dimeric structure of the complex in the solid state and in solution was thoroughly confirmed using appropriate analytical techniques: single crystal X-ray diffraction analysis, HRMS, FTIR and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

In the present study, the structure, thermal stability, conductive properties, and antimicrobial activity of silver(I) complexes with nitrile ligands were investigated. For the construction of the materials, 2‐cyanopyridine (2‐cpy), 4‐cyanopyridine (4‐cpy), 1,2‐dicyanobenzene (1,2‐dcb), and 1,3‐dicyanobenzene (1,3‐dcb) were used in addition to the silver nitrite and nitrate. Four new compounds were isolated and structurally characterized: one molecular complex [Ag4(1,2‐dcb)4(NO3)4], two 1‐D coordination polymers [Ag(2‐cpy)2(NO2)]∞, [Ag2(1,3‐dcb)2(NO3)2]∞, and one 3‐D coordination polymer [Ag(4‐cpy)(NO2)]∞. The results indicate that the nitrile complexes display good antimicrobial properties against the tested bacterial and fungal strains. The presence of weakly coordinating CN groups increases the release of silver ions into the bacterial and yeast cell environments. Moreover, these materials exhibit unusual electrical properties in thin‐layer devices. On the other hand, the nitrite and nitrate counterions give rise to the low thermal stability of the complexes. [ABSTRACT FROM AUTHOR]

Here, we illustrate the use of formamide (fma) and anilato-type ligands to build two-dimensional lattices with lanthanoids. Thus, we describe the synthesis and crystal structure of four lattices formulated as [Ln2(C6O4X2)3(fma)6]·6fma with Ln/X = La/Cl (1), La/Br (2), Eu/Cl (3), and Eu/Br (4), where C6O4X22− = dianion of 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone with X = Cl (chloranilato) and X = Br (bromanilato). Single crystal X-ray analysis shows that the four compounds crystallize in the triclinic P-1 space group and present two-dimensional, very distorted hexagonal lattices with the lanthanoids ions in the vertex coordinated by three anilato ligands forming the sides of the distorted hexagons that appear as rectangles. The rectangles are disposed parallel to their long sides in a brick wall fashion. The nona-coordination of the lanthanoids is completed by three formamide molecules. These layered compounds include three additional formamide molecules per lanthanoid atom, located in the interlayer space inside the channels formed by the eclipsed packing of the layers. We discuss the differences observed among these compounds due to the change of the lanthanoid ion (La and Eu) and of the substituent group X in the anilato ligand (Cl and Br). [ABSTRACT FROM AUTHOR]

Rhenium(I) complexes of type [Re(CO)3(NN)Cl] (NN = α-diimine) with MLCT absorption in the orange-red region of the visible spectrum have been synthesized and fully characterized, including single crystal X-ray diffraction on two complexes. The strong bathochromic shift of MLCT absorption was achieved through extension of the π-system of the electron-poor bidiazine ligand 4,4′-bipyrimidine by the addition of fused phenyl rings, resulting in 4,4′-biquinazoline. Furthermore, upon anionic cyclization of the twisted bidiazine, a new 4N-doped perylene ligand, namely, 1,3,10,12-tetraazaperylene, was obtained. Electrochemical characterization revealed a significant stabilization of the LUMO in this series, with the first reduction of the azaperylene found at E 1 / 2 (0 / −) = −1.131 V vs. Fc+/Fc, which is the most anodic half-wave potential observed for N-doped perylene derivatives so far. The low LUMO energies were directly correlated to the photophysical properties of the respective complexes, resulting in a strongly red-shifted MLCT absorption band in chloroform with a λmax = 586 nm and high extinction coefficients (ε586nm > 5000 M−1 cm−1) ranging above 700 nm in the case of the tetraazaperylene complex. Such low-energy MLCT absorption is highly unusual for Re(I) α-diimine complexes, for which these bands are typically found in the near UV. The reported 1,3,10,12-tetraazaperylene complex displayed the [Re(CO)3(α-diimine)Cl] complex with the strongest MLCT red shift ever reported. UV–Vis NIR spectroelectrochemical investigations gave further insights into the nature and stability of the reduced states. The electron-poor ligands explored herein open up a new path for designing metal complexes with strongly red-shifted absorption, thus enabling photocatalysis and photomedical applications with low-energy, tissue-penetrating red light in future. [ABSTRACT FROM AUTHOR]

In the present work, novel polymeric copper(II) coordination compounds, namely [Cu2(cpida)(H2O)4][Cu(cpida)]·3H2O (1) (cpida3− = 2-(carboxyphenyl)iminodiacetate anion) and Na[Cu(cpida)] (3), were synthesized and characterized using infrared spectroscopy, thermogravimetric analysis, elemental analysis, and single-crystal X-ray diffraction. Compound 1 was obtained by slowly evaporating an aqueous solution of H3cpida, copper(II) sulfate, and NaOH at room temperature. The structural characterization revealed that 1 is an ionic entity formed by the [Cu(cpida)]− anion and the [Cu2(cpida)(H2O)4]+ cation, both of polymeric 1D structure. Compound 3 was prepared under similar conditions from copper perchlorate and crystallized via acetone diffusion. It is a coordination polymer formed by the [Cu(cpida)]− units, and the sodium cation is present in the structure, counterbalancing the anion charge. Depending on the crystallization conditions, it was possible to obtain other solvation forms of these structures. Starting from the conditions of compound 1, via the diffusion of ethanol, [Cu2(cpida)(H2O)4][Cu(cpida)]·H2O·1/2EtOH (2) was precipitated, while a hydrate form of compound 3 with the formula Na[Cu(cpida)]·2H2O (4) was obtained via methanol diffusion.

Mono benzoxazine appended N‐capped amino bis(disubstitutedphenol) ligands [II(a–c)] upon reaction with VVO(OEt)3 in a 1 : 1 molar ratio in EtOH/MeOH give [{VVO}en(3,5‐dtbb)3] (1), [{VVO}en(3‐tb,5‐mb)3] (2) and [{VVO}en(3,5‐dmb)3] (3). During the reaction, the benzoxazine ring opens with the loss of methylene group and the newly formed ligands, N,N‐bis(2‐hydroxy‐3,5‐disubstitutedbenzyl)‐N'‐2‐hydroxy‐3,5‐disubstituted benzyledene‐1,2‐diaminoethane [III(a–c)], behave as tribasic pentadentate in these complexes. Under similar conditions, when [MVIO2(acac)2] (M=Mo or W; Hacac=acetylacetone) reacts with II(a–c), these ligands retain their identity and form cis‐[MVIO2] complexes, [{MoVIO2}{en(3,5‐dtbb)2(6,8‐dtbbenzox)}] (4), [{MoVIO2}{en(3‐tb,5‐mb)2(6‐tb,8‐mbbenzox)}] (5) and [{MoVIO2}{en(3,5‐dmb)2(6,8‐dmbenzox)}] (6), [{WVIO2}{en(3,5‐dtbb)2(6,8‐dtbbenzox)}] (7), and [{WVIO2}{en(3‐tb,5‐mb)2(6‐tb,8‐mbbenzox)}] (8). However, the benzoxazine ring ruptures in case of ligand IIc under these conditions and form [{WVIO2}{en(3,5‐dmb)3}] (10), similar to complexes 1–3. Complex [{WVIO2}{en(3,5‐dmb)2(6,8‐dmbenzox)}] (9), having structure similar to 4–8, could only be obtained when the reaction was carried out in toluene. Not only 9, even complexes 4–8 can be isolated in toluene. Rupturing of both benzoxazine rings has also been experienced when ligands 1,2‐bis(6,8‐disubstitutedbenzo[e][1,3]oxazin‐3(4H)‐yl)ethane [I(a–c)] react with [MVIO2(acac)2] (M=Mo or W) in MeOH and give salan type complexes [(MVIO2)en(3,5‐dtbb)2] [M=Mo (11), M=W (14)], [(MVIO2)en(3‐tb,5‐mb)4] [M=Mo (12), M=W (15)] and [(MVIO2)en(3,5‐dmb)4] [M=Mo (13), M=W (16)]. Complexes 1–9 have been used as catalyst for the multicomponent Biginelli reaction for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones (DHPMs) and oxidative bromination of phenol derivatives. [ABSTRACT FROM AUTHOR]

Cytochrome P450 (CYP) heme‐thiolate monooxygenases catalyze the hydroxylation of the C−H bonds of organic molecules. This reaction is initiated by a ferryl‐oxo heme radical cation (Cpd I). These enzymes can also catalyze sulfoxidation reactions and the ferric‐hydroperoxy complex (Cpd 0) and the Fe(III)‐H2O2 complex have been proposed as alternative oxidants for this transformation. To investigate this, the oxidation of 4‐alkylthiobenzoic acids and 4‐methoxybenzoic acid by the CYP199A4 enzyme from Rhodopseudomonas palustris HaA2 was compared using both monooxygenase and peroxygenase pathways. By examining mutants at the mechanistically important, conserved acid alcohol‐pair (D251N, T252A and T252E) the relative amounts of the reactive intermediates that would form in these reactions were disturbed. Substrate binding and X‐ray crystal structures helped to understand changes in the activity and enabled an attempt to evaluate whether multiple oxidants can participate in these reactions. In peroxygenase reactions the T252E mutant had higher activity towards sulfoxidation than O‐demethylation but in the monooxygenase reactions with the WT enzyme the activity of both reactions was similar. The peroxygenase activity of the T252A mutant was greater for sulfoxidation reactions than the WT enzyme, which is the reverse of the activity changes observed for O‐demethylation. The monooxygenase activity and coupling efficiency of sulfoxidation and oxidative demethylation were reduced by similar degrees with the T252A mutant. These observations infer that while Cpd I is required for O‐dealkylation, another oxidant may contribute to sulfoxidation. Based on the activity of the CYP199A4 mutants it is proposed that this is the Fe(III)‐H2O2 complex which would be more abundant in the peroxide‐driven reactions. [ABSTRACT FROM AUTHOR]

Here, we illustrate the use of formamide (fma) and anilato-type ligands to build two-dimensional lattices with lanthanoids. Thus, we describe the synthesis and crystal structure of four lattices formulated as [Ln2(C6O4X2)3(fma)6]·6fma with Ln/X = La/Cl (1), La/Br (2), Eu/Cl (3), and Eu/Br (4), where C6O4X22− = dianion of 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone with X = Cl (chloranilato) and X = Br (bromanilato). Single crystal X-ray analysis shows that the four compounds crystallize in the triclinic P-1 space group and present two-dimensional, very distorted hexagonal lattices with the lanthanoids ions in the vertex coordinated by three anilato ligands forming the sides of the distorted hexagons that appear as rectangles. The rectangles are disposed parallel to their long sides in a brick wall fashion. The nona-coordination of the lanthanoids is completed by three formamide molecules. These layered compounds include three additional formamide molecules per lanthanoid atom, located in the interlayer space inside the channels formed by the eclipsed packing of the layers. We discuss the differences observed among these compounds due to the change of the lanthanoid ion (La and Eu) and of the substituent group X in the anilato ligand (Cl and Br).

The crystal structures of bis[1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-ium-4-yl)-1,4- dihydroquinoline-3-carboxylato]copper(II) sulfate heptahydrate, [Cu(C16H18FN3O3) 2]SO4.7H2O or [Cu(nor)2]SO4.7H2O (nor is norfloxacin), and bis{1-[2- (ethylsulfonyl)ethyl]-2-methyl-5-nitroimide}dinitratocopper(II), [Cu(NO3)2- (C8H13N3O4S)2] or [Cu(NO3)2(tnz)2] (tnz is tinidazole), were solved by X-ray diffraction. Both complexes crystallize in the space group P21/c, with Z = 4 (for nor) and Z = 2 (for ntz) molecules per unit cell. In [Cu(nor)2]SO4.7H2O, the CuII ion is at the centre of a square-planar environment, trans coordinated to two independent norfloxacin molecules in the zwitterionic form acting as bidentate ligands through one of the carboxyl (cbx) and the carbonyl (cb) O atoms. The solid is further stabilized by an extensive network of N--H. . .O(sulfate), N--H. . .O(cbx), N--H. . .OW, OW--H. . .O(sulfate) and OW--H. . .OW hydrogen bonds. The [Cu(NO3)2(tnz)2] complex is centrosymmetric, with the CuII ion in a square planar environment, coordinated to a tinidazole molecule acting as a monodentate ligand through its imidazole N atom and to one nitrate O atom. The vibrational FT-IR absorption spectra and thermal behaviour of the complexes were also studied and are briefly discussed based on the crystal structures. [ABSTRACT FROM AUTHOR]

A new complex, [Ni(Tren)(Barb)(H2O)](Barb)(Barb-H)·2H2O (NiC) {Tren = tris(2-aminoethyl)amine and Barb = 5,5-diethlybarbiturate}, has been synthesized and characterized. The nickel(II) complex was grafted to g-C3N4, forming NiC@g-C3N4. The obtained NiC complex and its hybrid material NiC@g-C3N4 were characterized by FT-IR, TGA-DSC, UV–vis, SEM-EDX, and XRD. Single crystal X-ray crystallography shows that NiC exhibits NiN5O octahedral geometry. The results also show that the complex molecules are connected via N–H⋅⋅⋅⋅O hydrogen bonds. The complex NiC and NiC@g-C3N4 show oxidative stress effects on in vivo experiments. They also showed an increase in tissue damage markers that are represented by increase in tissue levels of malondialdehyde (MDA) in brain, liver, kidney and heart. Both materials showed inhibitory activity for examined antioxidants such as glutathione-S-transferase (GST), superoxide dismutase (SOD), glutathione (GSH) and glutathione reductase (GSH-R). The destructive effects were clearer for the NiC@g-C3N4 composite in liver, brain and kidney, respectively. The grafting of NiC complex in g-C3N4 is responsible for improving the catalytic activity of the compound, due to the synergistic effect of both components and facile recovery, as well recycling of the catalyst. The immobilization of the synthesized nickel(I) complex [Ni(Tren)(Barb)(H2O)](Barb)(Barb-H)•2H2O (NiC) to the graphitic carbon nitride (g-C3N4) as electron rich surface, forming the hybrid material NiC@g-C3N4, which provides both the benefits i.e improved catalytic activity owing to the synergistic effect of both components and facile recovery, recycling of the catalyst. [ABSTRACT FROM AUTHOR]

The reaction of the tridentate ligand bis(2-picolyl)amine (BPA) with the chloride or perchlorate salts of zinc(II) ions yielded two zinc(II) complexes of the types: [(BPA)ZnCl2]·2H2O (1) and [(BPA)2Zn](ClO4)2 (2). The intermediate complex species, namely [(BPA)Zn(OH)(H2O)](ClO4) (3) and [(BPA)Zn-OP(= S)(CH3)2] (4) were successfully isolated separately in good yields and pure forms. Complexes 1–4 were characterized in the solid state by using elemental analyses, thermal analyses, FT-IR, and X-ray single crystal diffraction as well as in solution by using 1H NMR titration and cyclic voltammetry (CV). From X-ray structural and spectral features it can be concluded that the coordination environment around Zn(II) ion in 1 is a distorted square pyramidal geometry with τ5 value of 0.148. Whereas in 2, two picolyl chelates in the equatorial plane and two slightly longer axial pyridines are coordinated in a distorted octahedral trans-facial arrangement. Kinetic studies were performed on these complexes to evaluate their efficiency as functional hydrolase models for the hydrolysis of the toxic organophosphate insecticide, Fenitrothion. The pH-dependence of the catalytic rate gives a bell-shaped curve, which gives a strong proof that the hydroxoaqua complex [(BPA)Zn(H2O)(OH)]− 3 is the catalytically active species in the hydrolysis reactions than that of the octahedral [(BPA)2Zn]2+ with fully saturated coordination sphere. [ABSTRACT FROM AUTHOR]

The serine 244 to aspartate (S244D) variant of the cytochrome P450 enzyme CYP199A4 was used to expand its substrate range beyond benzoic acids. Substrates, in which the carboxylate group of the benzoic acid moiety is replaced were oxidised with high activity by the S244D mutant (product formation rates >60 nmol.(nmol‐CYP)−1.min−1) and with total turnover numbers of up to 20,000. Ethyl α‐hydroxylation was more rapid than methyl oxidation, styrene epoxidation and S‐oxidation. The S244D mutant catalysed the ethyl hydroxylation, epoxidation and sulfoxidation reactions with an excess of one stereoisomer (in some instances up to >98 %). The crystal structure of 4‐methoxybenzoic acid‐bound CYP199A4 S244D showed that the active site architecture and the substrate orientation were similar to that of the WT enzyme. Overall, this work demonstrates that CYP199A4 can catalyse the stereoselective hydroxylation, epoxidation or sulfoxidation of substituted benzene substrates under mild conditions resulting in more sustainable transformations using this heme monooxygenase enzyme. [ABSTRACT FROM AUTHOR]

The studies reported here focus on the extraction of La(III), Eu(III), and Yb(III) by chelating hexadentate 3-alkoxy-2-hydroxyphenyl substituted diimine ligands using the extraction system Ln(NO3)3–Zn(NO3)2–NaNO3–buffer–H2O/diimine-n-caprylic acid–CHCl3. Significant synergistic enhancement has been observed for the Ln(III) extraction from nitrate media in the presence of Zn(II) and n-caprylic acid. These effects can be interpreted by self-assembly of heterodinuclear Zn(II)/Ln(III) complexes with both deprotonated extractants in the organic phase taking into account solution and solid-state structural studies. The structures identified and the extraction behavior as well as the different factors influencing the process will be discussed in detail. The goals of these experiments are to find preferred structure-extractability relationships for the synergistic systems investigated. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of ligands bound to proteins is an important task in medicinal chemistry and drug design. However, the dominant technique for determining protein–ligand structures, X‐ray crystallography, does not fully account for dynamics and cannot accurately describe the movements of ligands in protein binding sites. In this article, an alternative method, ensemble refinement, is used on six protein–ligand complexes with the aim of understanding the conformational diversity of ligands in protein crystal structures. The results show that ensemble refinement sometimes indicates that the flexibility of parts of the ligand and some protein side chains is larger than that which can be described by a single conformation and atomic displacement parameters. However, since the electron‐density maps are comparable and Rfree values are slightly increased, the original crystal structure is still a better model from a statistical point of view. On the other hand, it is shown that molecular‐dynamics simulations and automatic generation of alternative conformations in crystallographic refinement confirm that the flexibility of these groups is larger than is observed in standard refinement. Moreover, the flexible groups in ensemble refinement coincide with groups that give high atomic displacement parameters or non‐unity occupancy if optimized in standard refinement. Therefore, the conformational diversity indicated by ensemble refinement seems to be qualitatively correct, indicating that ensemble refinement can be an important complement to standard crystallographic refinement as a tool to discover which parts of crystal structures may show extensive flexibility and therefore are poorly described by a single conformation. However, the diversity of the ensembles is often exaggerated (probably partly owing to the rather poor force field employed) and the ensembles should not be trusted in detail. [ABSTRACT FROM AUTHOR]

Three new platinum(II) complexes, [Pt(en)(tu)2](NO3)2 (1), [Pt(en)(dmtu)2] (NO3)2 (2) and [Pt(en)(tmtu)2](NO3)2 (3) (where en = ethylenediamine, tu = thiourea, dmtu = 1,3-dimethyl-2-thiourea and tmtu = 1,1,3,3-tetramethy-2-thiourea), have been synthesized and characterized using elemental analysis, IR spectroscopy and NMR spectroscopy. All complexes are soluble in high polarity solvents. Single crystals have been obtained by slow evaporation of methanol solution at room temperature. NMR studies show that the amide proton signals shift downfield while the thiocarbonyl carbon signals shift upfield as compared to free thioureas. These opposite chemical shifts suggest that there is a decrease in thiocarbonyl bond order and an increase in thiocarbonyl carbon-amide nitrogen bond order for the thioureas upon coordination to platinum(II). The molecular structures of the crystallized complexes have been identified by single crystal X-ray diffraction. Both 1 and 2 crystallize in the monoclinic space groups P2(1)/c and P2(1)/n, respectively, while 3 crystallizes in the orthorhombic space group C222(1). X-ray crystallographic analysis indicates that the geometry about the platinum atom is square-planar and the crystal packings are dominated by intermolecular en N − H⋅⋅⋅O (NO3-) and tu N − H⋅⋅⋅O (NO3-) hydrogen bonds. [ABSTRACT FROM AUTHOR]

Solution speciation of Rh(η5-C5Me5), Ru(η6-p-cymene) and Ru(η6- toluene) complexes of 2,4-pyridinedicarboxylic acid (2,4-dipicH2) was studied and compared to that of 2-picolinic acid (picH) in addition to their reactivity towards chloride and bromide ions, 1-methylimidazole and guanosine. Structures of [Rh(η5- C5Me5)(2,4-dipicH)Cl] ·3H2O (1), 2[Ru(η6-toluene)(2,4-dipicH) Cl] ·3H2O (2) and [Ru(η6-toluene)(2,4-dipic)]3 ·7H2O (3) were analyzed by X-ray diffraction. 1 and 2 show typical piano stool geometry, while 3 is a triangular complex stabilized via the monodentate coordination of the second carboxylate group to the neighboring Ru(II) center. High stability [M(arene)L(H2O/Cl)] species predominate at pH 7.4. 2,4-Dipic forms more stable complexes with Ru(η6-arene) than pic, with this difference being minor in the case of the Rh(η5-C5Me5) complexes. A lower affinity of 2,4-dipic complexes to halide ions was found compared to the corresponding pic complexes due to the additional COO- moiety. [ABSTRACT FROM AUTHOR]

Fungal pathogens present a challenge in medicine and agriculture. They also harm ecosystems and threaten biodiversity. The allylamine class of antimycotics targets the enzyme squalene monooxygenase. This enzyme occupies a key position in the sterol biosynthesis pathway in eukaryotes, catalyzing the rate-limiting reaction by introducing an oxygen atom to the squalene substrate converting it to 2,3-oxidosqualene. Currently, terbinafine—the most widely used allylamine—is mostly used for treating superficial fungal infections. The ability to better target this enzyme will have significant implications for human health in the treatment of fungal infections. The human orthologue can also be targeted for cholesterol-lowering therapeutics and in cancer therapies. This review will focus on the structural basis for improving the current therapeutics for fungal squalene monooxygenase. [ABSTRACT FROM AUTHOR]

The reaction of 1,10-phenanthroline and dicyanamide ligands with Cu(II) and Co(II) nitrates afforded the complexes [Cu(phen)(BMCA)](NO3)] (1) and [Co(phen)2(NO3)](dcg-)·(H2O) (2). The dicyanamide anion was transformed in 1 and 2 to bis(methoxycarbimido)aminato (BMCA) and dicyanoguanidinate (dcg) anions, respectively. The complexes were characterized by elemental analysis, infrared spectroscopy and ultraviolet–visible spectroscopy, magnetic susceptibility measurement and X-ray crystallography. Both complexes crystallize in the monoclinic crystal system, and the structures are stabilized by extended hydrogen bonding networks as well as aromatic π–π stacking interactions. The thermal and antimicrobial properties of the complexes have also been evaluated. Density functional theory calculations were also performed in order to gain insights into the molecular interactions in the synthesized compounds and to predict some of their electronic properties. [ABSTRACT FROM AUTHOR]

Neisseria gonorrhoeae (Ng) and Chlamydia trachomatis (Ct) are the most commonly reported sexually transmitted bacteria worldwide and usually present as co‐infections. Increasing resistance of Ng to currently recommended dual therapy of azithromycin and ceftriaxone presents therapeutic challenges for syndromic management of Ng‐Ct co‐infections. Development of a safe, effective, and inexpensive dual therapy for Ng‐Ct co‐infections is an effective strategy for the global control and prevention of these two most prevalent bacterial sexually transmitted infections. Glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) is a validated drug target with two approved drugs for indications other than antibacterials. Nonetheless, any new drugs targeting GAPDH in Ng and Ct must be specific inhibitors of bacterial GAPDH that do not inhibit human GAPDH, and structural information of Ng and Ct GAPDH will aid in finding such selective inhibitors. Here, we report the X‐ray crystal structures of Ng and Ct GAPDH. Analysis of the structures demonstrates significant differences in amino acid residues in the active sites of human GAPDH from those of the two bacterial enzymes suggesting design of compounds to selectively inhibit Ng and Ct is possible. We also describe an efficient in vitro assay of recombinant GAPDH enzyme activity amenable to high‐throughput drug screening to aid in identifying inhibitory compounds and begin to address selectivity. [ABSTRACT FROM AUTHOR]

• Methods for the synthesis of high nuclearity carbonyl clusters of ruthenium and osmium. • Analysis of the structures of high nuclearity carbonyl clusters of ruthenium and osmium. • Osmium and ruthenium clusters with nuclearities greater than 6 metals. • Linked higher nuclearity clusters. • Mixed-metal clusters containing ruthenium or osmium. In this review the synthetic and structural chemistry of osmium and ruthenium clusters is described with emphasis on the studies carried out during the 1980s and 1990s when research in the area was prolific. The methods of cluster synthesis are discussed as are the techniques used to characterise the complexes. The electron counting methods that are used to predict and rationalise the cluster structures are highlighted. Emphasis is placed on the synthetic methods used to build high nuclearity carbonyl clusters of osmium and ruthenium, namely vacuum pyrolysis, the linking of cluster fragments with bridging ligands, and the development of methodologies used to build higher nuclearity mixed-metal clusters. [ABSTRACT FROM AUTHOR]

Three new iodo-bridged copper(I) complexes of the type [CuI(PPh 3)L] 2 , where L = Ar–≡–C 5 H 4 N, Ar = phenyl (C 1), biphenyl (C 2) and flourenyl (C 3) have been synthesized via coordination-driven self-assembly processes. Two of Cu(I) complexes, C 2 and C 3 , have been characterized by single-crystal X-ray diffraction studies. The complexes have two molecules of the P-donor ligand and two molecules of the N-donor ligand in trans configurations, supporting the central Cu 2 I 2 unit. Absorption properties of the complexes have been investigated. Extensive DFT calculation has been carried out to delineate the influence of aromatic spacers on the optical properties and the nature of excited states. The ease of synthesis of these Cu(I) dimers and the wide range of ethynylpyridine supporting ligands that can be incorporated highlights the potential for these materials to form polymers by linking through the ethylylpyridine ligands. Image 1 • Three new ethynylpyridinyl-based Cu(I) complexes were synthesized and characterized. • Structures of two complexes were confirmed by single crystal X-ray diffraction. • Photo-physical and computational studies were performed. [ABSTRACT FROM AUTHOR]

The reaction between [Cu(μ-OAc)(μ-Pip)(MeOH)] 2 and isonicotinamide as an auxiliary ligand in different solvents resulted in the formation of five Cu(II) compounds. The X-ray single crystal diffraction method show three different structural arrays: dimeric, paddle-wheel and monomeric. The extended structures are studied and Hirshfeld surface analysis allows its better understanding and comparison. • Reactions between [Cu(μ-OAc)(μ-Pip)(MeOH)] 2 and isonicotinamide ligand have been performed. • Different solvents promoted the formation of different structural arrays. • The crystal structure of dimeric, paddle-wheel and monomeric compounds have been elucidated. • The supramolecular structure of all these compounds have been studied and compared via Hirshfeld surface analysis. • Isonicotinamide acts as a supramolecular driving force. Five solvent-dependent Cu(II) compounds have been synthesized with [Cu(μ-OAc)(μ-Pip)(MeOH)] 2 (OAc = acetate; Pip = 1,3-benzodioxolecarboxylate) and isonicotinamide (Isn) as an auxiliary ligand in different solvents. In all the compounds, Pip units are displaced resulting in dimeric [Cu(μ-OAc)(OAc)(Isn) 2 (solvent)] 2 (solvent = MeOH (2a), dmf and H 2 O (3) or H 2 O and HPip (4a)), paddle-wheel [Cu(μ-OAc) 2 (Isn)] 2 ·2dmso (5) or monomeric compounds [Cu(OAc) 2 (HOAc)(Isn) 2 ]·HOAc (6). All of them have been characterized by analytical and ATR-FTIR techniques and their X-ray crystal structures solved. The OAc anions construct different arrays and exhibit different coordination modes depending on the solvent used. The supramolecular expansion is constantly determined by the amide-amide pattern and the role of the occluded solvent molecules. This tendency is confirmed by Hirshfeld Surface analysis. Finally, the thermal stability of compound 4a has been analyzed. [ABSTRACT FROM AUTHOR]

Half-sandwich organometallic complexes of curcumin are extensively investigated as anticancer compounds. Speciation studies were performed to explore the solution stability of curcumin complexes formed with [Rh(η5-C 5 Me 5)(H 2 O) 3 ]2+. Acetylacetone (Hacac), as the simplest β-diketone ligand bearing (O,O) donor set, was involved for comparison and its Ru(η6‑ p ‑cymene), Ru(η6‑toluene) complexes were also studied. 1H NMR, UV–visible and pH-potentiometric titrations revealed a clear trend of stability constants of the acac complexes: Ru(η6‑ p ‑cymene) > Ru(η6‑toluene) > Rh(η5-C 5 Me 5). Despite this order, the highest extent of complex formation is seen for the Rh(η5-C 5 Me 5) complexes at pH 7.4. Formation constant of [Rh(η5-C 5 Me 5)(H 2 curcumin)(H 2 O)]+ reveals similar solution stability to that of the acac complex. Additionally, structures of two complexes were determined by X-ray crystallography. The in vitro cytotoxicity of curcumin was not improved by the complexation with these organometallic cations. Solution stability of Ru(II)(η6‑toluene), Ru(II)(η6‑ p ‑cymene) and Rh(III)(η5-C 5 Me 5) complexes of acetylacetone was determined in aqueous solution and compared with that of other (O,O) donor ligands. The structures of [Rh(III)(η5-C 5 Me 5)(H 2 curcumin)]+ and [Ru(II)(η5-toluene)(acetylacetonato)]+ were resolved by single crystal X-ray diffraction. Their cytotoxicity was evaluated in multidrug resistant human cancer cell lines. Unlabelled Image • Solution stability of Ru(arene) and Rh(C 5 Me 5) complexes of acac and curcumin • Acac is used as curcumin binding model. • X-ray crystal structures of two complexes and comparison with analogous structures • Antiproliferative activity against multidrug resistant human cancer cell lines • Human serum albumin binding and interaction with cell culture medium components [ABSTRACT FROM AUTHOR]

Abstract Two new Cd(II) complexes [Cd(L) (H 2 O) 2 ]·(ClO 4) 2 (1) and [Cd(L) (SCN) 2 ]·(H 2 O) (2) involving pyrimidine based tetradentate schiff base ligand 2,2'-((2E, 2′E)-2,2'-(butane-2,3-diylidene)bis (hydrazin-1-yl-2-ylidene))bis (4,6-dimethylpyrimidine) (L) are reported in this work. Both the complexes 1 and 2 are synthesized and characterized by elemental analyses, UV, IR, single crystal X-ray diffraction studies accordingly. Both of them are pseudooctahedral in geometry. In this report we want to highlight the variation of supramolecular non-covalent interactions in the solid state as a consequence of both apical ligand substitution (replacement of neutral aqua molecules by thiocyanate ion) and substitution of noncoordinating anionic counterions by coordinating anions. Complex 1 exhibits H-bonding, π ... π stacking, CH ... π and anion ... π interaction whereas complex 2 displays π ... π stacking and CH ... π interaction only. The electronic transitions of both 1 and 2 were recorded and the electronic distribution of HOMO - LUMO can be rationalized theoretically (through time-dependent density functional theory (TDDFT)). Graphical abstract Image 1 Highlights • Two new Cd(II) complexes have been synthesized derived from pyrimidine derived ligand. • Both the complexes 1 and 2 have pseudooctahedral geometry. • The various non covalent interactions lead to various supramolecular architectures. • TDDFT (Time-dependent density functional theory) calculation is carried out for both 1 and 2. [ABSTRACT FROM AUTHOR]

The reactions of piperonylic acid (HPip) and cinnamic acid (HCinn) with 4,4’-bipyridine (4,4’-bipy) have been assayed using the same synthetic methodology, yielding two binary cocrystals with different acid:4,4’-bipy molar ratios, (HPip)(4,4’-bipy) (1) and (HCinn)2(4,4’-bipy) (2). The melting point (m.p.) of these cocrystals have been measured and a remarkable difference (ΔT ≈ 78 °C) between them was observed. Moreover, the two cocrystals have been characterized by powder X-ray diffraction (PXRD), elemental analysis (EA), FTIR-ATR, 1H NMR spectroscopies, and single-crystal X-ray diffraction. The study of their structural packings via Hirshfeld surface analysis and energy frameworks revealed the important contribution of the π···π and C-H···π interactions to the formation of different structural packing motifs, this being the main reason for the difference of m.p. between them. Moreover, it has been observed that 1 and 2 presented the same packing motifs as the crystal structure of their corresponding carboxylic acids, but 1 and 2 showed lower m.p. than those of the carboxylic acids, which could be related to the lower strength of the acid-pyridine heterosynthons respect to the acid-acid homosynthons in the crystal structures.

The synthesis and characterization of one coordination polymer and two trinuclear complexes are presented. The coordination polymer [Zn2(µ-O,O’-ACA)2(ACA)2(4-Phpy)2]n (1) has been obtained by the reaction between Zn(OAc)2·2H2O, α-acetamidocinnamic acid (HACA), and 4-phenylpyridine (4-Phpy) using EtOH as solvent. Its recrystallization in CH3CN or EtOH yields two trinuclear complexes, both having pinwheel arrays with formulas [Zn3(µ-ACA)6(4-Phpy)2]·4CH3CN (2·4CH3CN) and [Zn3(µ-ACA)6(EtOH)2]·4EtOH (3·4EtOH), respectively. These trinuclear species, unavoidably lose their solvent co-crystallized molecules at RT yielding the complexes [Zn3(µ-ACA)6(4-Phpy)2] (2) and [Zn3(µ-ACA)6(EtOH)2] (3). In addition, compound 2 has also been obtained reacting Zn(OAc)2·2H2O, HACA, and 4-Phpy in a 1:2:2 ratio using CH3CN as solvent. Compounds 1–3 have been characterized by analytical and spectroscopic techniques. Furthermore, single crystals suitable for X-ray diffraction method for compounds 1, 2·4CH3CN, and 3·4EtOH were obtained and their supramolecular interactions have been studied and discussed, showing 2D supramolecular planes for the trinuclear complexes and a 3D supramolecular network for the coordination polymer. Finally, the supramolecular interactions of 2·4CH3CN and 3·4EtOH have been compared using Hirshfeld surface analysis and electrostatic potential calculations.

Graphical abstract Two three-dimensional mononuclear zinc(II) and trinuclear copper(II) complexes, [Zn(L2) 2 ]·2CH 3 OH (1) and [Cu(L2)] 3 ·CH 3 OH (2) (HL2 = 1-(2-{[(E)-3-bromo-5-chloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), were synthesized via complexation of metal salts with based ligand HL1 (2-(3-bromo-5-chloro-2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazoline 3-oxide, H is the deprotonatable hydrogen) originally. FT-IR, UV–Vis and fluorescence spectroscopic data of both complexes were compared with the ligand HL1. Both complexes were characterized by X-ray single-crystal diffraction and reveal that 1 has 2:1 whereas 2 has 1:1 ligand-to-metal ratio. In the crystal structures, both complexes form an infinite 1-D chain-like and 2-D, 3-D supramolecular frameworks. Moreover, antimicrobial activity of 2 was also studied. Density functional theory (DFT) calculations were carried out to ascertain the optimum geometry structure of two complexes, is devoted to the analysis of the interesting supramolecular assemblies in the solid state of the structures. In addition, the noncovalent interactions among complexes have been also analyzed using Hirshfeld surface analysis. Abstract Two three-dimensional mononuclear zinc(II) and trinuclear copper(II) complexes, [Zn(L2) 2 ]·2CH 3 OH (1) and [Cu(L2)] 3 ·CH 3 OH (2) (HL2 = 1-(2-{[(E)-3-bromo-5-chloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), were synthesized via complexation of metal salts with based ligand HL1 (2-(3-bromo-5-chloro-2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazoline 3-oxide, H is the deprotonatable hydrogen) originally. FT-IR, UV–Vis and fluorescence spectroscopic data of both complexes were compared with the ligand HL1. Both complexes were characterized by X-ray single-crystal diffraction and reveal that 1 has 2:1 whereas 2 has 1:1 ligand-to-metal ratio. In the crystal structures, both complexes form an infinite 1-D chain-like and 2-D, 3-D supramolecular frameworks. Moreover, antimicrobial activity of 2 was also studied. Density functional theory (DFT) calculations were carried out to ascertain the optimum geometry structure of two complexes, is devoted to the analysis of the interesting supramolecular assemblies in the solid state of the structures. In addition, the noncovalent interactions among complexes have been also analyzed using Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The conformation hypothesis for LY354740 and its analogs was reexamined. • A new steric hindrance hypothesis to account for their selectivity was proposed. • This was supported by the crystal structures of the mGlu ATD proteins. Abstract Analogs based on the 2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate scaffold showed high potency and selectivity as both group II mGlu receptors orthosteric agonists and antagonists. This scaffold was initially designed to mimic the fully extended glutamate backbone conformation that was hypothesized to be the active conformation for the group II mGlu receptors. With the availability of crystal structures of l -Glu-bound amino terminal domain proteins from multiple mGlu receptor subtypes spanning all three subgroups, a new steric hindrance hypothesis was proposed to account for the scaffold's unique group II selectivity that explores the subtle distance differences between the α-carbon of l -Glu and the center of the tyrosine phenyl ring from the bottom lobe (e.g. Y216 of mGlu 2). [ABSTRACT FROM AUTHOR]

Highlights • Diverse tridentate meridional pyridine–pyrrolide ligands readily available. • κ3-N pyridine–pyrrolide metal complexes comprehensively reviewed. • Critical analysis of electronic and structural properties and of reactivity. • Future prospects identified spanning the breadth of contemporary chemistry. Abstract This review covers all aspects of the chemistry of metal complexes of tridentate κ3-N pyridine–pyrrolide ligands, from the syntheses of the ligands to what is known about the metal complexes – their structural and physical properties, and their reactivities, including use in catalytic processes. Applications of the complexes range from the switching elements in molecular devices, to luminophores in electroluminescent devices and photosensitisers in light-driven catalyses, to anticancer therapeutics and to efficient catalysts for organic transformations. The general properties of the ligands and metal complexes are deduced from the available literature, and areas of κ3-N pyridine–pyrrolide metal complex chemistry ripe for development are pinpointed. [ABSTRACT FROM AUTHOR]

Abstract Therapeutic treatment of tuberculosis (TB) is becoming increasingly problematic due to the emergence of drug resistant Mycobacterium tuberculosis (Mt). Thus, new targets for anti-TB drug discovery need to be identified to combat and eradicate this disease. One such target is hypoxanthine-guanine phosphoribosyltransferase (HGPRT) which synthesises the 6-oxopurine nucleoside monophosphates essential for DNA/RNA production. [3R,4R]-4-Hypoxanthin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine and [3R,4R]-4-guanin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine (compound 6) are the most potent inhibitors of Mt HGPRT yet discovered having K i values of 60 nM. The crystal structure of the Mt HGPRT. 6 complex was obtained and compared with that of human HGPRT in complex with the same inhibitor. These structures provide explanations for the 60-fold difference in the inhibition constants between these two enzymes and a foundation for the design of next generation inhibitors. In addition, crystal structures of Mt HGPRT in complex with two pyrrolidine nucleoside phosphosphonate inhibitors plus pyrophosphate provide insights into the final stage of the catalytic reaction. As the first step in ascertaining if such compounds have the potential to be developed as anti-TB therapeutics, the tetra-(ethyl L-phenylalanine) tetraamide prodrug of 6 was tested in cell based assays. This compound arrested the growth of virulent Mt not only in its replicating phase (IC 50 of 14 μΜ) but also in its latent phase (IC 50 of 29 μΜ). Furthermore, it arrested the growth of Mt in infected macrophages (MIC 50 of 85 μΜ) and has a low cytotoxicity in mammalian cells (CC 50 of 132 ± 20 μM). These inhibitors are therefore viewed as forerunners of new anti-TB chemotherapeutics. Graphical abstract Image 1 Highlights • A new class of inhibitors of Mt HGPRT, the pyrrolidine nucleoside phosphonates and bisphosphonates, have been discovered. • Crystal structures of the Mt HGPRT.I complexes show how these compounds bind to the active site. • A prodrug of these inhibitors arrest the growth of replicating and dormant TB cells. [ABSTRACT FROM AUTHOR]

The synthesis of bis(N-methylbenzimidazol-2-yl)methane serves as the entry point for the preparation of a tetrabenzimidazole-based binucleating ligand. A cupric complex of the former compound was prepared to compare its properties to those of the dicopper complexes of the tetrabenzimidazole derivative. In the latter case, the reaction of the binucleating ligand with cupric trifluoromethylsulfonate in air results in intramolecular C H activation with concomitant hydroxylation, presumably by an in situ formed copper-oxygen reactive intermediate. This reactivity highlights the relevance of benzimidazole-based scaffolds in biologically inspired copper-oxygen systems. [ABSTRACT FROM AUTHOR]

Dichloro[3-(pyridin-2-yl)-1,2,4-triazinone]Pd(II) undergoes oxidative C–C coupling reaction with cyclopentanone and cyclohexanone at 110°C to yield the respective Pd complexes, chloro[1-(4-chlorophenyl)-5-(2-hydroxycyclopent-1-enyl)-3-(pyridin-2-yl)-1,2,4-triazin-6(1H)-one]palladium(II) (3) and chloro[1-(4-chlorophenyl)-5-(2-hydroxycyclohex-1-enyl)-3-(pyridin-2-yl)-1,2,4-triazin-6(1H)-one]palladium(II) (4). The structures of both complexes are supported by spectral data and confirmed by single-crystal X-ray crystallography. The molecules 3 and 4 stack to form tunnel structures, whilst the geometry around the palladium ion is square planar. [ABSTRACT FROM AUTHOR]

The present investigation was carried out with the aim of synthesizing and characterizing five vanadium coordination compounds ( 6 – 10 ) with different Schiff bases ( 1  = N,N′-bis(salicylidene)- o -phenylenediamine, 2  = N,N′-bis(4-hydroxysalicylidene)- o -phenylenediamine, 3  = N,N′-bis(4-methoxysalicylidene)- o -phenylenediamine, 4  = N,N′-bis(3-hydroxysalicylidene)- o -phenylenediamine, 5  = N,N′-bis(3-methoxysalicylidene)- o -phenylenediamine) and studying their cytotoxic properties. Based on their physical (magnetic susceptibility), spectral (X-ray, electronic, IR, 1 H NMR, 13 C NMR, EPR and mass) and analytical (elemental analysis) results, the structures of these Schiff bases and their respective oxidovanadium(IV) complexes were established. Crystal structures of compounds 6 (Monoclinic, C 2/c, Z = 16) and 7 – 8 (Triclinic, P-1, Z = 2) had been determined by X-ray diffraction and confirmed pentacoordination of vanadium(IV) with a slightly distorted square-pyramidal geometry. Vanadium coordination compounds displayed low effective magnetic moments (0.85–0.89 BM) that maybe due to the intermolecular hydrogen bonding and π-stacking interactions in the crystal arrangements. Cytotoxic activity was evaluated on human tumor cell lines: 6 – 9 (HeLa = 0.443–1.502 μM) and 6 – 10 (HCT-15 = 0.373–1.415 μM), with exception of 7 . Cell growth inhibition revealed that regardless of the cancer cell line type compounds 6 and 8 showed similar activity -possible effect due to the complex per se - giving new insights into the structure–activity relationship for these complexes. [ABSTRACT FROM AUTHOR]

In the manuscript, photophysical, electrochemical and electroluminescent properties of the series of phenyl/methyl substituted 1 H -pyrazolo[3,4- b ]quinoxalines have been investigated. The fluorescent properties of these compounds varied significantly depending on the presence of phenyl substituent and its position in the molecule. Compared with the 1,3-dimethylpyrazoloquinoxaline (parent molecule), phenyl at the third position of pyrazole ring enhanced the fluorescence by increasing contribution of π-π* transitions, whereas 1-phenyl substituent led to the formation of polarity-dependent charge transfer state. The molecules were also tested as potential luminophores in double layer OLED devices fabricated by solution processing techniques. The investigated pyrazoloquinoxaline based OLED's emitted green light with appreciable brightness up to 2820 cd/m 2 . [ABSTRACT FROM AUTHOR]

New series of trans - and cis -3-methylseleno substituted β-lactams ( 4 , 5 ) have been prepared from 2-methylselenoethanoic acid ( 2 ). The four-membered β-lactam ring was introduced by the condensation reaction between ketene retrieved from 2-methylselenoethanoic acid ( 2 ) and suitably substituted imines ( 3a-f) in the presence of triethylamine using POCl 3 in refluxing toluene. The structural and stereochemical analysis of novel trans - and cis -3-methylseleno substituted β-lactams were carried out using IR, NMR ( 1 H and 13 C), 2D-NMR ( 1 H– 1 H COSY, 1 H– 13 C HSQC), elemental analysis (CHN) and mass spectrometry (EIMS). Further, the structures of trans -1-(4′-methoxyphenyl)-3-methylseleno-4-(4′-chlorophenyl)azetidin-2-one ( 4b ), trans -1-(4′-methoxyphenyl)-3-methylseleno-4-(4′-methylphenyl)azetidin-2-one ( 4c ), trans - and cis -1-(4′-methoxyphenyl)-3-methylseleno-4-styrylazetidin-2-ones ( 4e and 5e ) were established by single crystal X-ray crystallographic studies. The cis or trans configuration of the hydrogen at C-3 was assigned with respect to C4-H. [ABSTRACT FROM AUTHOR]

The trinuclear copper(II) compounds [Cu 3 (μ 3 -OH)( G L1) 3 ](ClO 4 ) 2 ( 1 – 4 ) and [Cu 3 (μ 3 -OH)( G L2) 3 ](ClO 4 ) 2 ( 5 – 8 ) with tridentate NNO Schiff base ligands G L1 − and G L2 − derived from 5-G-substituted salicylaldehydes (G = NO 2 , Br, H, Me) and the diamines 1,2-ethanediamine and 1,3-propanediamine, respectively, were investigated aiming at shedding light on possible magneto-structural correlation in this class of complexes. All derivatives contain [Cu 3 (μ 3 -OH)(L) 3 ] 2+ cations with partial cubane Cu 3 O 4 cores, and the metal ions are linked together in a pyramidal fashion by a triple-bridging hydroxido group, giving rise to propellers with three [Cu(L)] + blades. In these spin-frustrated magnetic systems, the three copper(II) ions within a cluster communicate anti-ferromagnetically (−2 J Ŝ i · Ŝ j convention) through the bridging OH group with coupling constants J ranging from −4.5(1) for 4 (G = Me) to −10.1(1) cm −1 for 1 (G = NO 2 ), and stabilization of the doublet S  = 1/2 ground state. The structural features of the complexes reveal very minimal deviations upon variation of G or the diamine flexibility along the whole series of compounds, preserving almost constant magnetic cores. Similar conclusions are also drawn by DFT gas-phase geometry optimizations of the [Cu 3 (μ 3 -OH)(L) 3 ] 2+ cations. Therefore, confident of excluding structural influences on the magnetic super-exchange path, the modulating factor of J in our derivatives can be sought after the different electronic demand of G. Atomic NBO charges support this point, revealing small but systematic variations in the electron density flow along the blades and the positive charge on copper(II) ions with the electronic nature of G, with the most remarkable effect given by the nitro group. Topological analysis of electron density according to the Quantum Theory of Atoms In Molecules further support the distinguishing role of this group with respect to the other substituents taken into consideration, besides providing indirect information about the super-exchange path. [ABSTRACT FROM AUTHOR]

The second-generation xanthate ligand 4-PyCH 2 OCS 2 Na, consisting of a backbone functionalized O -alkyldithiocarbonate donor set, has been prepared. The reaction of this ligand with either Ph 3 SnCl or (Ph 3 P) 2 CuNO 3 yields the neutral monometallic complexes [4-PyCH 2 OCS 2 SnPh 3 ] and [4-PyCH 2 OCS 2 Cu(PPh 3 ) 2 ], respectively. These compounds were characterized by 1 H NMR and UV–Vis spectroscopies, and in solid state by single crystal X-ray diffraction. The structure of [4-PyCH 2 OCS 2 SnPh 3 ] consists of a mono-dimensional coordination polymer, formed by the monodentate coordination of the O CS 2 − group to the Sn(IV) center, in combination with the coordination of the pyridine group to an adjacent tin atom. In the case of [4-PyCH 2 OCS 2 Cu(PPh 3 ) 2 ], the xanthate ligand coordinates to the Cu(I) center in an isobidentate fashion, leaving the pyridine moiety free. These monometallic complexes act as metalloligands toward the [Rh 2 (OAc) 4 ] dimer, producing the tetrametallic derivatives [Rh 2 (OAc) 4 ]·2[4-PyCH 2 OCS 2 SnPh 3 ] and [Rh 2 (OAc) 4 ]·2[4-PyCH 2 OCS 2 Cu(PPh 3 ) 2 ], respectively. These compounds were investigated in solution phase using 1 H NMR and UV–Vis techniques, and it is proposed that the formation of the first compound proceeds via a two-step process, while the formation of the latter is a one-step process. [ABSTRACT FROM AUTHOR]

The heterocyclic ligands 2,6-bis(pyrazol-1-yl)pyridine (L 1 ) and 2,6-bis(benzimidazol-2-yl)pyridine (L 2 ) and their cobalt(II) complexes were synthesized. The blue five-coordinate complex [Co(L 1 )Cl 2 ] isolated initially from the reaction mixture rapidly absorbed water vapour from the atmosphere to yield the pink six-coordinate complex [Co(L 1 )(H 2 O) 3 ]Cl 2 . This change is reversible upon desiccation or transferring [Co(L 1 )(H 2 O) 3 ]Cl 2 into acetonitrile. The five coordinate complex [Co(L 2 )Cl 2 ], however, remains stable under similar conditions. The structures of the complexes [Co(L 1 )Cl 2 ], [Co(L 1 )(H 2 O) 3 ]Cl 2 and [Co(L 2 )Cl 2 ] have been determined by x-ray crystallography. The magnetic susceptibilities and the electronic spectra for [Co(L 1 )Cl 2 ], [Co(L 2 )Cl 2 ] and [Co(L 1 )(H 2 O) 3 ]Cl 2 are presented. [ABSTRACT FROM AUTHOR]

Five Ru(II)(η 6 -toluene) complexes formed with 2-picolinic acid and its various derivatives have been synthesized and characterized. X-ray structures of four complexes are also reported. Complex formation processes of [Ru(II)(η 6 -toluene)(H 2 O) 3 ] 2+ organometallic cation with the metal-free ligands were studied in aqueous solution in the presence of chloride ions by the combined use of 1 H NMR spectroscopy, UV–visible spectrophotometry and pH-potentiometry. Solution stability, chloride ion affinity and lipophilicity of the complexes were characterized together with in vitro cytotoxic and antiproliferative activity in cancer cell lines being sensitive and resistant to classic chemotherapy and in normal cells as well. Formation of mono complexes such as [Ru(η 6 -toluene)(L)(Z)] +/0 (L: completely deprotonated ligand; Z = H 2 O/Cl − ) with high stability and [Ru(η 6 -toluene)(L)(OH)] was found in solution. The p K a values (8.3–8.7) reflect the formation of low amount of mixed hydroxido species at pH 7.4 at 0.2 M KCl ionic strength. The complexes are fairly hydrophilic and show moderate chloride ion affinity and fast chloride-water exchange processes. The studied complexes exhibit no cytotoxic activity in human cancer cells (IC 50  > 100 μM), only complexes formed with 2-picolinic acid ( 1 ) and its 3-methyl derivative ( 2 ) represented a moderate antiproliferative effect (IC 50  = 84.8 ( 1 ), 79.2 μM ( 2 )) on a multidrug resistant colon adenocarcinoma cell line revealing considerable multidrug resistant selectivity. Complexes 1 and 2 bind to human serum albumin covalently and relatively slowly with moderate strength at multiple binding sites without ligand cleavage. [ABSTRACT FROM AUTHOR]

Crystal structures of solvated highly nonplanar nickel(II) and copper(II) complexes of 2,3,5,10,12,13,15,20- octaphenylporphyrin are determined by single crystal XRD analysis. The macrocycles in these systems exhibit mainly ruffled and saddled conformations. The average displacement of the pyrrole carbon atom ΔCb from the mean plane of the porphyrin ring is as high as ±0.70 Å. The Hirshfeld surface analysis of both structures reveals mainly H…H (57-59%) intermolecular short contacts with a smaller contribution from C…H (16-22%) and H…Cl (11-19%) interactions. The present work suggests that the nonplanarity of the macrocycle in NiTPP(Ph)4 is largely due to the core Ni(II) ion and less influenced by intermolecular interactions/crystal packing forces, whereas the opposite is true in the case of the nonplanar CuTPP(Ph)4 structure. [ABSTRACT FROM AUTHOR]

We report here on a new coordination heterometallic [MnII–BaII] polymer with 2,3-pyridinedicarboxylic bridging ligand and its application as single-source for access to perovskite oxide BaMnO 3. The structure and magnetic properties of both coordination compound and the obtained oxide have been investigated. The tridentate and pentadentate 2,3-pyridinedicarboxylic ligands bridge MnII and BaII heteroatoms forming a 3D coordination polymer. The XRD and EDX results confirm the formation of the hexagonal phase of pure BaMnO 3 perovskite.The magnetic and EPR spectroscopy measurements of 2 show characteristic structural and magnetic transitions reported for 2H–BaMnO3. Fragment of structure 1 illustrate the coordination surrounding of the metal cations, connectivity of the ligands, and formation of six membered water cluster. [Display omitted] • A new heterometallic {[MnBa(2,3-pdc) 2 (H 2 O) 5 ]·3H 2 O]} n complex has been synthetized. • The heterometallic complex was used as single-source for obtaining BaMnO 3 perovskite. • The XRD and EDX results confirm the formation of hexagonal phase of BaMnO 3. • The magnetic measurements of complex clearly indicate paramagnetic behavior. [ABSTRACT FROM AUTHOR]