An Oxalato-Bridged Cu(II)-Based 1D Polymer Chain: Synthesis, Structure, and Adsorption of Organic Dyes.

In the current research, we prepared a polymeric framework, {[Cu(C2O4)(C10H8N2)]·H2O·0.67(CH3OH)]}n (1) (where C2O4 = oxalic acid; C10H8N2 = 2,2-bipyridine), and explored this compound for adsorption of methylene blue (MB) and methyl orange (MO). The crystal structure of the compound consists of a Cu(ox)(bpy) unit connected via oxalate to form a 1D polymeric chain. This polymeric chain has adsorption capacities of 194.0 and 167.3 mg/g for MB and MO, respectively. The removal rate is estimated to be 77.6% and 66.9% for MB and MO, respectively. The plausible mechanisms for adsorption are electrostatic, π-π interaction, and OH-π interaction for dye stickiness. The adsorbent surface exhibits a negative charge that produces the electrostatic interaction, resulting in excellent adsorption efficiency at pH 7 and 8. The pseudo-first-order kinetic model is selected for the adsorption of MB and MO on the adsorbent. The reported compound has remarkable efficiency for sorption of organic dyes and can be useful in wastewater treatment.

A new hexanuclear Fe(III) nanocluster: synthesis, structure, magnetic properties, and efficient activity as a precatalyst in water oxidation.

The oxo-bridged hexanuclear iron cluster formulated [FeIII6(µ4-O)2(edteH)2(piv)4(SCN)4]·2MeCN·2H2O (1) (where edteH = N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine; piv = pivalic acid) has been synthesized by the reaction of FeCl2·4H2O with edteH4 and piv in the presence of KSCN in CH2Cl2/MeCN. The single crystal X-ray measurements indicated that the cluster is centrosymmetric in structure. The magnetic study demonstrated the presence of very strong antiferromagnetic coupling between the iron centers and the Brillouin fitting showed the best fit with S = 5/2 and g = 1.87. In addition, the water oxidation activity of the cluster has been studied by electrochemical techniques. Electrochemical experiments revealed that the electrode modified by 1 has high efficiency for the oxidation of water and needs an overpotential of 484 mV under a constant current density of 15 mA cm-2 with a Tafel slope of 114 mV dec-1 in neutral media. Experiments indicated that in the presence of 1, a yellow solid film was formed on the electrode surface under the applied electrochemical conditions. This yellow material is likely a compound of iron and oxygen and has a crystalline nature. Our findings revealed that along with the cluster, this compound is active in water oxidation reactions.

Structure, DFT studies and evaluation of catechol oxidase (CO) mimic activity of mononuclear Co(II) complexes derived from aminoalcohols: an experimental and theoretical approach.

The impetus to modeling of enzyme mimics comes from their potential to provide insight to the alternate mechanistic pathways of the native enzymes. The present study demonstrates the syntheses and characterization of two different cobalt(II) complexes, [Co(pdm)(Phen)Cl]Cl·H2O (1) and [Co(pmmH)2(SCN)2] (2) with the aminoalcohol ligands such as pyridine-2,6-dimethanol (pdmH2) or 2-pyridinemonomethanol (pmmH) and their assessment as catechol oxidase (CO) enzyme mimic. Single Crystal X-ray diffraction and powder X-ray diffraction data suggest the octahedral environment around the Co(II) ion and the complexes form extensive 1D or 2D propagating network as a result of non-covalent interactions (O···H and C-H···π). TD-DFT calculations were used to explain the spectral bands obtained during the UV-Vis absorption studies and it is ascertained that the transitions were mainly of the intra-ligand charge transfer (ILCT) type. The catecholase biomimetic catalytic activity of the synthesized complexes has been investigated in detail and the kinetics is also performed. The results obtained show that both the complexes catalyze the aerobic oxidation of catechol to the corresponding o-quinone. The Kcat value for 1 is 106.99 h‒1 and for 2 is 90.32 h‒1 in methanol. It may be mentioned here that 1 and 2 are effective catalysts, with the order of activity being 1 > 2. The order of enzymatic activity is well justified by CV and DFT studies.Communicated by Ramaswamy H. Sarma.

Exploring the Role of Intramolecular Interactions in the Suppression of Quantum Tunneling of the Magnetization in a 3d-4f Single-Molecule Magnet.

Hydroxide-bridged FeIII4LnIII2 clusters having the general formula [Fe4Ln2(µ3-OH)2(mdea)6(SCN)2(NO3)2(H2O)2]·4H2O·2MeCN {Ln = Y (1), Dy (2), mdea = N-methyldiethanolamine} were synthesized and magnetically characterized. The thermal relaxation of the magnetization for 2 and the diluted FeIII4DyIIIYIII complex 3 (with and without applied field) has been analyzed. The diluted sample shows a dominant QTM at low temperatures that can be removed with a 0.15 T dc field. Both 2 and 3 show moderately high Ueff barriers and exhibit hysteresis loops until 5 K.

Synthesis, Characterization and Biological Evaluation of Metal Adamantyl 2-Pyridylhydrazone Complexes.

Four new complexes derived from adamantly containing hydrazone (APH) ligand with Cu(II) (1), Co(II) (2), Ni(II) (3) and Zn(II) (4), have been synthesized and characterized using different physicochemical methods. The structure of the ligand APH and its copper complex 1 have been established by single-crystal X-ray diffraction direct methods, which reveal that complex 1 has distorted square-pyramidal geometry. Complexes 1-4 are screened against seven human cancer cell lines namely, breast cancer cell lines (MCF7, T47D, MDA-MB-231), prostate cancer cell lines (PC3, DU145) and the colorectal cancer cell line Coco-2, for their antiproliferative activities. Complex 1 has shown a promising anticancer activity compared to the other ones. The structural and spectroscopic analysis of APH and its complexes are confirmed by DFT calculations.

Synthesis, Characterization, Crystal Structure, and DFT Study of a New Square Planar Cu(II) Complex Containing Bulky Adamantane Ligand.

A copper complex with square planar geometry, [(L)CuBr2] (1), (L = N'-(furan-2-ylmethylene)adamantne-1-carbohydrazide) has been synthesized and characterized by Fourier transfer infrared (FTIR) spectroscopy, elemental analysis, mass spectrometry, and single crystal X-ray diffraction. The crystal of 1 is solved as monoclinic, space group P21/m with unit cell parameters: a = 10.8030(8), b = 6.6115(8), c = 12.1264(12) Å, ß = 101.124(8)°, V = 849.84(15) ų, Z = 2, and R1 = 0.0751 with wR2 = 0.1581 (I > 2 σ). The structure of 1 shows intramolecular hydrogen bonding between the N-H and the furan oxygen which stabilizes the configuration of the complex. Furthermore, inside the lattice there are other weak interactions between bromo ligands and the ligand L. DFT calculations where performed to study the stability of this geometry.

Effect of ligand substitution on the SMM properties of three isostructural families of double-cubane Mn4Ln2 coordination clusters.

Three isostructural lanthanide series with a core of MnMnLn2 are reported. These three families have the formulae of [MnMnLn2(µ4-O)2(H2edte)2(piv)6(NO3)2] {no crystallization solvent, Ln = La, Ce, Pr, Nd, Eu (1-4, 6); solv = 3MeCN, Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y (5, 7-13)}, where H2edte = N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine and piv = pivalate; [MnMnLn2(µ4-O)2(H2edte)2(benz)6(NO3)2], where benz = benzoate, or [MnMnLn2(µ4-O)2(edteH2)2(benz)6(NO3)2]·2MeCN {Ln = Gd, Tb, Dy (14-16); and [MnMnLn2(µ4-O)2(edteH2)2(piv)8].solv {solv = 4MeCN, Ln = La (17); solv = 2MeCN·tol·H2O, Ln = Pr, Nd, Sm, Tb (18-20, 22); solv = 2MeCN·H2O, Ln = Gd (21). These compounds crystallize in two different systems, namely, monoclinic in the space groups P21/n for 1-4, 6, and 14-16 and C2/c for 5, 7-13, 18-20, and 22 and triclinic in the space group P1[combining macron] for 17 and 21. The crystal structures of these compounds display a face-fused dicubane structure connected by different types of bridged oxygen atoms. Solid-state dc magnetic susceptibility characterization was carried out for 1-22, and fitting showed that MnIIIMnIII is antiferromagnetically (AF) coupled and MnIIMnIII, MnIILn and MnIIILn are weakly ferromagnetically coupled. In addition, ac measurements were carried out and showed that only 7, 15, and 22 for Tb, 8 and 16 for Dy, and 20 for Sm exhibited slow magnetization relaxation. In the case of 15, it was possible to determine the energy barrier of the slow-relaxation behavior by fitting peak temperatures to the Arrhenius law, which gave a value of Ueff = 21.2 K and a pre-exponential factor of τ0 = 4.0 × 10-9 s.

Synthesis, characterization, X-ray structure, computational studies, and bioassay of novel compounds combining thiophene and benzimidazole or 1,2,4-triazole moieties.

BACKGROUND: Due to their interesting and versatile biological activity, thiophene-containing compounds have attracted the attention of both chemists and medicinal chemists. Some of these compounds have anticancer, antibacterial, antiviral, and antioxidant activity. In addition, the thiophene nucleus has been used in the synthesis of a variety of heterocyclic compounds. RESULTS: In the present work, two novel thiophene-containing compounds, 4-phenyl-2-phenylamino-5-(1H-1,3-a,8-triaza-cyclopenta[α]inden-2-yl)-thiophene-3-carboxylic acid ethyl ester (3) and 5-(1H-Imidazo[1,2-b] [1,2,4] triazol-5-yl)-4-phenyl-2-phenylamino-thiophene-3-carboxylic acid ethyl ester (4), have been synthesized by reaction of 5-(2-bromo-acetyl)-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ethyl ester (2) with 2-aminobenzimidazole and 3-amino-1H-1,2,4-triazole in the presence of triethylamine, respectively. Compound 2, on the other hand, was prepared by bromination of 5-acetyl-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ester (1). Structures of the newly prepared compounds were confirmed by different spectroscopic methods such as 1H-NMR, 13C-NMR, and mass spectrometry, as well as by elemental analysis. Furthermore, bromination of compound 1 led to the formation of two constitutional isomers (2a and 2b) that were obtained in an 80:20 ratio. Molecular structures of 2b were confirmed with the aid of X-ray crystallography. Compound 2 was crystallized in the triclinic, P-1, a = 8.8152 (8) Å, b = 10.0958 (9) Å, c = 12.6892 (10) Å, α = 68.549 (5)°, ß = 81.667 (5)°, γ = 68.229 (5)°, V = 976.04 (15) Å3, Z = 2, and was found in two isomeric forms regarding the position of the bromine atom. The antibacterial and antifungal activities of the prepared compounds were evaluated. CONCLUSIONS: Three new thiophene derivatives were synthesized in good yield. Antimicrobial screening revealed that compound 3 was a promising candidate as a potential antibacterial and antifungal agent; it exhibits remarkable activity against the studied bacterial strains, especially the gram negative bacteria E. coli in addition to some fungi. More work is needed to evaluate its safety and efficacy.

3D oxalato-bridged lanthanide(iii) MOFs with magnetocaloric, magnetic and photoluminescence properties.

Four isostructural 3D lanthanide(iii) metal-organic frameworks with the general formula (H6edte)0.5[LnIII(ox)2(H2O)] (Ln = Gd (1), Tb (2), Dy (3) and Ho (4); H4edte = N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine) and ox = oxalate have been synthesized from oxalate. These compounds were characterized using single-crystal X-ray diffraction, FTIR and TGA/DTG. The magnetic investigation has been performed for 1-4 and the results reveal that a Gd(iii) containing MOF has the highest magnetic density and exhibits a larger cryogenic magnetocaloric effect (ΔSm = 35.9 J kg-1 K-1 for ΔH = 9 T at 2.0 K) with a high Debye temperature (θD = 342(3) and rD = 35). For the Dy derivative, an ac-out-of-phase signal was found, and further measurements under an applied field of 1000 Oe showed frequency-dependent out-of-phase magnetic susceptibility. Solid-state luminescence indicates that Tb and Dy-containing complexes are photoluminescent materials.

4-Chloro-butyl 7-chloro-1-cyclo-propyl-4-(1,3-diethyl-4,6-dioxo-2-sulfanyl-idene-1,3-diazinan-5-yl-idene)-6-fluoro-1,4-di-hydro-quinoline-3-carboxyl-ate.

The title compound, C25H26Cl2FN3O4S, contains two bio-active moieties (thio-barbituric acid and fluoro-quinolone). In the crystal, mol-ecules are linked via C-H⋯O and C-H⋯F hydrogen bonds, forming two-dimensional slab-like networks lying parallel to the bc plane. The benzene ring substituted by F and Cl atoms and the 4-chloro-butyl group seem to be partly disordered, however attempts to model the disorder were unsuccessful.

Bis{(E)-3-[(2-hy-droxy-benzyl-idene)amino]-prop-yl}ammonium chloride.

The title salt, C20H26N3O2(+)·Cl(-), lies across a twofold crystallographic axis with the central N atom of the cation and the chloride anion sitting on this axis, Z' = 0.5. There is an intra-molecular hydrogen bond between the hy-droxy H atom and the imino N atom. The chloride anion and the cation are connected into chains along the a axis by an N-H⋯Cl hydrogen bond. In the crystal, the chains are linked via C-H⋯Cl interactions forming two-dimensional networks lying parallel to (101).

trans-Dichlorido(2,2-dimethyl-propane-1,3-diamine)-bis-(triphenyl-phosphane)ruthenium(II).

In the title compound, [RuCl(2)(C(5)H(14)N(2))(C(18)H(15)P)(2)], the Ru(II) atom is six-coordinated, forming a slightly distorted octa-hedral geometry, with two chloride ions in an axial arrangement, and two P atoms of two triphenyl-phosphane and two chelating N atoms of the bidentate 2,2-dimethyl-propane-1,3-diamine ligand located in the equatorial plane. The average Ru-P, Ru-N and Ru-Cl bond lengths are 2.325 (18), 2.1845 (7) and 2.4123 (12) Å, respectively.

Mononuclear lanthanide single molecule magnets based on the polyoxometalates [Ln(W5O18)2]9- and [Ln(beta2-SiW11O39)2]13- (Ln(III) = Tb, Dy, Ho, Er, Tm, and Yb).

The first two families of polyoxometalate-based single-molecule magnets (SMMs) are reported here. Compounds of the general formula [Ln(W(5)O(18))(2)](9-) (Ln(III) = Tb, Dy, Ho, and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Tb, Dy, Ho, Er, Tm, and Yb) have been magnetically characterized with static and dynamic measurements. Slow relaxation of the magnetization, typically associated with SMM-like behavior, was observed for [Ln(W(5)O(18))(2)](9-) (Ln(III) = Ho and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Dy, Ho, Er, and Yb). Among them, only the [Er(W(5)O(18))(2)](9-) derivative exhibited such a behavior above 2 K with an energy barrier for the reversal of the magnetization of 55 K. For a deep understanding of the appearance of slow relaxation of the magnetization in these types of mononuclear complexes, the ligand-field parameters and the splitting of the J ground-state multiplet of the lanthanide ions have been also estimated.

Mononuclear lanthanide single-molecule magnets based on polyoxometalates.

[ErW10O36]9- is the first polyoxometalate behaving as a single-molecule magnet (SMM). It shows frequency-dependent out-of-phase magnetization and a thermally activated single relaxation process with an effective barrier of 55.8 K. This single lanthanide ion polyoxometalate is the inorganic analogue of the bis(phthalocyaninato)lanthanide SMMs, both exhibiting very similar ligand field symmetries around the lanthanide ion (idealized D4d). It is chemically stable and offers new avenues for organization and processing of single-molecule magnets. Furthermore, it can be made free from nuclear spins and opens the possibility to be used for studies of decoherence on unimolecular qubits.

Effects of variable docking conditions and scoring functions on corresponding protein-aligned comparative molecular field analysis models constructed from diverse human protein tyrosine phosphatase 1B inhibitors.

The effects of variable docking conditions and scoring functions on corresponding protein-aligned comparative molecular field analysis (CoMFA) models have been assessed. To this end, a group of diverse inhibitors were docked into the active site of human protein tyrosine phosphatase 1B (h-PTP 1B). The docked structures were utilized to construct corresponding protein-aligned CoMFA models by employing probe-based (H+, OH, CH3) energy grids and genetic partial least squares (G/PLS) statistical analysis. A total of 48 different docking configurations were evaluated, of which some succeeded in producing self-consistent and predictive CoMFA models. However, the best CoMFA model coincided with docking the un-ionized ligands into the hydrated form of the binding site via the PLP1 scoring function and restricted docking settings (r2(LOO) = 0.647, r2(PRESS) against 27 test compounds = 0.617). Interestingly, the most significant CoMFA models were orthogonal and corresponded to significantly different docked conformers/poses. To utilize the predictive potentials of the best CoMFA models collectively, it was decided to combine them in a single quantitative structure-activity relationship (QSAR) model. The combination model illustrated excellent statistical properties (r2(LOO) = 0.890, r2(PRESS) against 27 test compounds = 0.750).

Ligand-based assessment of factor Xa binding site flexibility via elaborate pharmacophore exploration and genetic algorithm-based QSAR modeling.

The flexibility of activated factor X (fXa) binding site was assessed employing ligand-based pharmacophor modeling combined with genetic algorithm (GA)-based QSAR modeling. Four training subsets of wide structural diversity were selected from a total of 199 direct fXa inhibitors and were employed to generate different fXa pharmacophoric hypotheses using CATALYST software over two subsequent stages. In the first stage, high quality binding models (hypotheses) were identified. However, in the second stage, these models were refined by applying variable feature weight analysis to assess the relative significance of their features in the ligand-target affinity. The binding models were validated according to their coverage (capacity as a three-dimensional (3D) database search queries) and predictive potential as three-dimensional quantitative structure-activity relationship (3D-QSAR) models. Subsequently, GA and multiple linear regression (MLR) analysis were employed to construct different QSAR models from high quality pharmacophores and explore the statistical significance of combination models in explaining bioactivity variations across 199 fXa inhibitors. Three orthogonal pharmacophoric models emerged in the optimal QSAR equation suggesting they represent three binding modes accessible to ligands in the binding pocket within fXa.