Anti‐proliferative activity of newly synthesized Cd(II), Cu(II), Zn(II),Ni(II), Co(II), VO(II), and Mn(II) complexes of 2‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐6‐yl)methylene) hydrazinecarbothioamide on three human cancer cells

Thiosemicarbazone ligand, 2‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐6‐yl)methylene) hydrazinecarbothioamide and its Cd(II), Cu(II), Zn(II), Ni(II), Co(II), VO(II), and Mn(II) complexes have been prepared and characterized by various spectroscopic and analytical techniques. Complexes molar conductance measurements displayed that all complexes (2–8) are non‐electrolyte. With general composition [M(H₃L)(CH₃COO)₂H₂O].nH₂O, where M = Cd(II), Cu(II), Zn(II), Ni(II), Co(II) and Mn(II) while complex (8) has [VO(H₃L)(SO₄)H₂O].2H₂O formula. Based on analytical and spectral measurements, the octahedral or distorted octahedral geometries suggested for complexes. Ligand and complexes anti‐proliferative activities were assessed against three various human tumor cell lines including breast cancer (MCF‐7), liver cancer (HepG2) and lung cancer (A549) using SRB fluorometric assay and cis‐platin as positive control. The anti‐proliferative activity result indicated that the ligand and its complexes have considerable anti‐proliferative activity analogous to that of ordinarily utilized anti‐cancer drug (cis‐platin). They do their anti‐cancer activities by modifying free radical's generation via raising the superoxide dismutase activity and depletion of intracellular reduced glutathione level, catalase, glutathione peroxidase activities, escorted by highly generation of hydrogen peroxide, nitric oxide and other free radicals leading to tumor cells death, as monitoring by decreasing the protein and nucleic acids synthesis.     

LAHS: A novel harmony search algorithm based on learning automata

This study presents a learning automata-based harmony search (LAHS) for unconstrained optimization of continuous problems. The harmony search (HS) algorithm performance strongly depends on the fine tuning of its parameters, including the harmony consideration rate (HMCR), pitch adjustment rate (PAR) and bandwidth (bw). Inspired by the spur-in-time responses in the musical improvisation process, learning capabilities are employed in the HS to select these parameters based on spontaneous reactions. An extensive numerical investigation is conducted on several well-known test functions, and the results are compared with the HS algorithm and its prominent variants, including the improved harmony search (IHS), global-best harmony search (GHS) and self-adaptive global-best harmony search (SGHS). The numerical results indicate that the LAHS is more efficient in finding optimum solutions and outperforms the existing HS algorithm variants.     

Chelating behavior, thermal studies and biocidal efficiency of tioconazole and its complexes with some transition metal ions

New seven metal complexes of tioconazole drug with the general formulae [MCl₂(L)₂(H₂O)_x].yH₂O (where, x = 0 and y = 1 for M = Mn(II) or x = 2, y = 2 for M = Co(II)), and x = 0, y = 3 for M = Cu(II), Ni(II), Zn(II)) and [MCl₂(L)₂(H₂O)₂]Cl.3H₂O (where M = Cr(III) and Fe(III)) have been prepared and characterized based on elemental analyses, IR, magnetic moment, molar conductance, and thermal analyses techniques. From molar conductance data bivalent metal chelates are non-electrolytes while Cr(III) and Fe(III) chelates are electrolytes and of 1:1 type. According to the IR spectral data, TCNZ is coordinated to the metal ions in a neutral unidentate manner with N donor site of the imidazole–N. All the complexes are octahedral except Mn(II) complex has tetrahedral structure. TCNZ drug and its metal complexes were also screened for their biological activity.     

Kinetic and mechanistic investigations of multielectron transfer reactions induced by stored electrons in TiO2 nanoparticles: a stopped flow study

The kinetics and the mechanism of various multielectron transfer reactions initiated by stored electrons in TiO(2) nanoparticles have been investigated employing the stopped flow technique. Moreover, the optical properties of the stored electrons in the TiO(2) nanoparticles have been studied in detail following the UV (A) photolysis of deaerated aqueous suspensions of TiO(2) nanoparticles in the presence of methanol. The reduction of common electron acceptors that are often present in photocatalytic systems such as O(2), H(2)O(2), and NO(3)(-) has been investigated. The experimental results clearly show that the stored electrons reduce O(2) and H(2)O(2) to water by multielectron transfer processes. Moreover, NO(3)(-) is reduced via the transfer of eight electrons evincing the formation of ammonia. On the other hand, the reduction of toxic metal ions, such as Cu(II), has been studied mixing their respective anoxic aqueous solutions with those containing the electrons stored in the TiO(2) particles. A two-electron transfer is found to occur, indicating the reduction of the copper metal ion into its non toxic metallic form. Other metal ions, such as Zn(II) and Mn(II), could not be reduced by TiO(2) electrons, which is readily explained on the bases of their respective redox potentials. The underlying reaction mechanisms are discussed in detail.     

Ruthenium(II) complexes with improved photophysical properties based on planar 4'-(2-pyrimidinyl)-2,2':6',2' '-terpyridine ligands

A series of new tridentate polypyridine ligands, made of terpyridine chelating subunits connected to various substituted 2-pyrimidinyl groups, and their homoleptic and heteroleptic Ru(II) complexes have been prepared and characterized. The new metal complexes have general formulas [(R-pm-tpy)Ru(tpy)]2+ and [Ru(tpy-pm-R)2]2+ (tpy = 2,2':6',2' '-terpyridine; R-pm-tpy = 4'-(2-pyrimidinyl)-2,2':6',2' '-terpyridine with R = H, methyl, phenyl, perfluorophenyl, chloride, and cyanide). Two of the new metal complexes have also been characterized by X-ray analysis. In all the R-pm-tpy ligands, the pyrimidinyl and terpyridyl groups are coplanar, allowing an extended delocalization of acceptor orbital of the metal-to-ligand charge-transfer (MLCT) excited state. The absorption spectra, redox behavior, and luminescence properties of the new Ru(II) complexes have been investigated. In particular, the photophysical properties of these species are significantly better compared to those of [Ru(tpy)2]2+ and well comparable with those of the best emitters of Ru(II) polypyridine family containing tridentate ligands. Reasons for the improved photophysical properties lie at the same time in an enhanced MLCT-MC (MC = metal centered) energy gap and in a reduced difference between the minima of the excited and ground states potential energy surfaces. The enhanced MLCT-MC energy gap leads to diminished efficiency of the thermally activated pathway for the radiationless process, whereas the similarity in ground and excited-state geometries causes reduced Franck Condon factors for the direct radiationless decay from the MLCT state to the ground state of the new complexes in comparison with [Ru(tpy)2]2+ and similar species.     

Isotype 1D polymers of cobalt(II) or zinc(II) constructed with square-planar tetraaqua-metal(2+) units and the bis-zwitterionic form of the μ2-O,O′-trans-1,4-dihydrogen-cyclohexanediaminotetraacetate(2−) ligand

An uncompleted reaction between equimolar amounts of Co₂CO₃(OH)₂·2H₂O and trans-1,4-H₄cyclohexanediaminotetraacetic acid in water affords the ‘acid’ complex {[Co^II(trans-1,4-H₂CDTA)(H₂O)₄]·6H₂O}_n (1). Its IR spectrum does not show the expected ν(CO) band of carboxylic groups. Reactions in aqueous solution between Na(trans-1,4-H₃CDTA) and Zn(AcO)₂·2H₂O or Na₂(trans-1,4-H₂CDTA) and Zn(NO₃)₂·6H₂O yield {[Zn(trans-1,4-H₂CDTA)(H₂O)₄]·6H₂O}_n (2) and {[Zn₂(trans-1,4-CDTA)(H₂O)₂]·H₂O}_n (3) respectively. Crystal structures of compounds 1-3 and that of the trans-1,4-H₄CDTA·2H₂O acid are reported. For steric reasons, in the four reported structures the 1,4-CDTA ligand has the two iminodiacetate moieties as equatorial groups in the 1,4-cyclohexanedi-yl chair. Compounds 1 and 2 are isotype 1D polymers constructed by square planar M^II(H₂O)₄²⁺ knots (M^II = Co^II or Zn^II) linked to bis-zwitterionic trans-1,4-H₂CDTA²⁻ ligands that play a typical μ₂-O,O′-dicarboxylate bridging role. These 1D polymeric structures seem to be favoured by the H-bonded intra-stabilization of the bis-zwitterionic trans-1,4-H₂CDTA²⁻ ligand. In the neutral complex (3), the trans-1,4-CDTA acts as a bridging bis-chelating ligand as well as a syn-anti carboxylate building a polymer where the zinc(II) centres exhibit a rough bipyramidal trigonal coordination.     

Rapid determination of NSAIDs by capillary and microchip electrophoresis with capacitively coupled contactless conductivity detection in wastewater

A simple, rapid method using CE and microchip electrophoresis with C⁴D has been developed for the separation of four nonsteroidal anti-inflammatory drugs (NSAIDs) in the environmental sample. The investigated compounds were ibuprofen (IB), ketoprofen (KET), acetylsalicylic acid (ASA), and diclofenac sodium (DIC). In the present study, we applied for the first time microchip electrophoresis with C⁴D detection to the separation and detection of ASA, IB, DIC, and KET in the wastewater matrix. Under optimum conditions, the four NSAIDs compounds could be well separated in less than 1 min in a BGE composed of 20 mM His/15 mM Tris, pH 8.6, 2 mM hydroxypropyl-beta-cyclodextrin, and 10% methanol (v/v) at a separation voltage of 1000–1200 V. The proposed method showed excellent repeatability, good sensitivity (LODs ranging between 0.156 and 0.6 mg/L), low cost, high sample throughputs, portable instrumentation for mobile deployment, and extremely lower reagent and sample consumption. The developed method was applied to the analysis of pharmaceuticals in wastewater samples with satisfactory recoveries ranging from 62.5% to 118%.     

Blue‐Emissive Cobalt(III) Complexes and Their Use in the Photocatalytic Trifluoromethylation of Polycyclic Aromatic Hydrocarbons

Room‐temperature luminescent Co^III complexes ( 1 and 2 ) are presented that exhibit intense ligand‐to‐metal and ligand‐to‐ligand charge transfer absorption in the low‐energy UV region (λ_abs≈360–400 nm) and low‐negative quasi‐reversible reduction events (E^1/2_(red)=?0.58 V and ?0.39 V vs. SCE for 1 and 2 , respectively). The blue emission of 1 and 2 at RT is due to the large bite angles and strong σ‐donation of the ligands, the combined effect of which helps to separate the emissive ³LMCT (triplet ligand‐to‐metal charge transfer) and the non‐emissive ³MC (triplet metal‐centered) states. 1 and 2 were found to be powerful photo‐oxidants (E =2.26 V and 2.75 V vs. SCE of 1 and 2 , respectively) and were used as inexpensive photoredox catalysts for the regioselective mono(trifluoromethylation) of polycyclic aromatic hydrocarbons (PAHs) in good yields (ca. 40–58 %).     

Shape resonances in slow electron scattering by aromatic molecules. I. Anthraquinone derivatives

A series of anthraquinone (C(14)O(2)H(8)) derivatives has been studied by means of electron capture negative ion mass spectrometry (ECNI-MS), photoelectron spectroscopy (PES), and AM1 quantum chemical calculations. Mean lifetimes of molecular negative ions M(-.) (MNI) have been measured. The mechanism of long-lived MNI formation in the epithermal energy region of incident electrons has been investigated. A simple model of a molecule (a spherical potential well with the repulsive centrifugal term) has been applied for the analysis of the energy dependence of cross sections at the first stage of the electron capture process. It has been shown that a temporary resonance of MNI at the energy approximately 0.5 eV corresponds to a shape resonance with lifetime 1-2.10(-13) s in the f-partial wave (l = 3) of the incident electron. The next resonant state of MNI at the energy approximately 1.7 eV has been associated with the electron excited Feshbach resonance (whose parent state is a triplet npi* transition). In all cases the initial electron state of the MNI relaxes into the ground state by means of a radiationless transition, and the final state of the MNI is a nuclear excited resonance with a lifetime measurable on the mass spectrometry timescale. Copyright 1999 John Wiley & Sons, Ltd.