Synthesis and characterization of peroxo complexes of uranium(VI) with aroylhydrazone ligands

The uranium(VI) peroxo complexes containing aroylhydrazones ligands having composition [UO(O₂)L-L(NO₃)₂]·H₂O (where L-L = Benzoic acid[1-(Furan-2-yl)methylene] hydrazide, Benzoic acid[(thiophene-2-yl)methylene] hydrazide, Benzoic acid[1-(thiophene-2-yl)ethylidene] hydrazide, Benzoic acid(phenylmethylene) hydrazide, Benzoic acid[1-(anisol-3-yl)methylene] hydrazide and Benzoic acid[(p-chlorobenzyl)methylene] hydrazide are reported. The complexes were characterized by various physico-chemical techniques, viz. elemental analysis, molar conductivity, magnetic susceptibility measurements, infra red, electronic, mass spectral and TGA/DTA studies. These studies revealed that complexes are non-electrolytes and diamagnetic in nature. The ligands are bound to metal in a bidentate mode. Thermal analysis results provide conclusive evidence for the presence of water molecules in the complexes. Mass spectra confirm the molecular mass of the complexes. Antifungal activity of complexes revealed enhanced activity of complexes as compared to the corresponding ligands.     

X-ray structurally characterized Mo (VI), Fe (III) and Cu (II) complexes of amide-imine conjugate: (bio)catalytic and histidine recognition studies

An amide-imine conjugate, (E)-N′-((2-hydroxybenzen-1-yl) methylene)-4-methylbenzohydrazide (H₂L^PTASAL), derived from 4-methyl-benzoic acid hydrazide (PTA) and 2-hydroxybenzaldehyde is used to prepare Mo (VI), Cu (II) and Fe (III) complexes. The X-ray structurally characterized complexes have been explored as catalyst for amine assisted asymmetric ring opening (ARO) of epoxide, carbon-heteroatom cross-coupling and ethyl benzene oxidation. In addition, their catecholase like activities have thoroughly been investigated. Moreover, the Cu (II) complex selectively recognizes histidine by fluorescence spectroscopy.     

Synthesis of coordination compounds of dibutyltin(IV) with Schiff bases having nitrogen donor atoms

The new dibutyltin(IV) complexes of Schiff bases is designed & synthesis from the interaction between various substituted amines and aromatic aldehyde with general formula Bu₂Sn(L^1-7)₂Cl₂. Where L¹: (E)-4-chloro-N-(thiophen-2-ylmethylene) aniline; L²: (E)-2-chloro-N-(3,4,5-trimethoxybenzylidene) aniline; L³: (E)-N-((1H-indol-3-yl) methylene)-4-chloro-2-nitroaniline; L⁴: (E)-4-nitro-N-(3,4,5-trimethoxybenzylidene) aniline; L⁵: (E)-N-(3,4,5-trimethoxybenzylidene) aniline; L⁶: (E)-4-nitro-N-(thiophen-3-ylmethylene) aniline; L⁷: (E)-4-chloro-2-nitro-N-(pyridin-3-ylmethylene) aniline. Analytical and spectroscopic methods, such as molar conductance measurement, UV–Vis, IR, NMR, and DFT studies, have been used to describe newly synthesised compounds. The DFT studies have also provided confirmation regarding the complexes' geometry. The results of the Tauc equation indicate that the fundamental band gap of the compound [Bu₂Sn(L⁵)₂Cl₂] is 2.670 eV, which is in agreement with the findings of DFT studies, which indicate that the band gap is 2.657 eV. The bactericidal effects of Schiff bases and their dibutyltin(IV) complexes were tested. The antibacterial activity of organotin(IV) complexes is enhanced in comparison to that of the free ligands.     

Mössbauer and other spectral studies of iron(II) complexes with amide-containing ligands

Summary Iron(II) complexes of the type [FeL₂X₂] (L=bidentate ligand, X=H₂O, Cl, or SCN) and [FeL₂] (L=tridentate ligand) with polydentate ligands derived from 2-(acetylamino)benzoic acid, 2-(benzoylamino)benzoic acid,2-[2-aminobenzoylamino]benzoic acid, 2-[amino-carbonyl]benzoic acid, 2-[(phenylamino)carbonyl]-benzoic acid, 2-[aminobenzoyl]benzoic acid and 2-aminobenzanilide have been synthesized and characterized by elemental analyses, conductivity, magnetic susceptibility and i.r., electronic, n.m.r., and Mossbauer spectral studies. The different modes of ligand chelation and the stereochemistry around the metal ion are discussed. The small range of isomer shift values for iron(II) complexes confirms the similar geometry for all the complexes.     

Biological evaluation of copper(II) complexes on N(4)−substituted thiosemicarbazide derivatives and diimine co-ligands using DNA interaction,antibacterial and in vitro cytotoxicity

Abstract

A number of alternatives were made to overcome numerous life-threatening infectious diseases by metal-based anticancer compounds. At present, thiosemicarbazones and their metal complexes have received significant consideration as a result of their metal DNA-interaction, structural diversity and availability of bonding modes. In this study, the coordination characteristics of nine diimine copper(II) complexes with sulfur containing ligands, [Cu(L)₂] (1–3), [Cu(L)(bpy)]Cl (4–6) and [Cu(L)(phen)]Cl (7–9) (L?=?H(L1)–H(L3), phen = 1,10-phenanthroline, bpy = 2,2′-bipyridyl, H(L1) = (Z)-2-((4-methoxynaphthalen-1-yl)methylene)-N-methylhydrazinecarbothioamide, H(L2) = (Z)-N-ethyl-2-((4-methoxynaphthalen-1-yl)methylene)hydrazinecarbothioamide and H(L3) = (Z)-2-((4-methoxynaphthalen-1-yl)methylene)-N-phenylhydrazinecarbothioamide] have been synthesized from 4-methoxy-1-naphthaldehyde along with N(4)-substituted thiosemicarbazide derivatives. The synthesized ligands and their Cu(II) complexes were characterized through different spectroscopic techniques and square-planar coordination was proposed. Biological evaluation such as DNA-cleavage, antibacterial and in vitro cytotoxicity of thiosemicarbazone ligands and their resultant Cu(II) complexes were analyzed. Interestingly, Cu(II) complex containing heteroaromatic moiety 9 had potential cytotoxic activity with strong DNA-interaction. In the future, these may be helpful to design more effective novel chemotherapeutic drugs.     

Syntheses of octasubstituted zinc azaphthalocyanines with thiophene or thiophene combined with sulfanyl,amino or imido substituents: Influence of the substituents on photochemical and photophysical properties

Several octasubstituted zinc azaphthalocyanines (ZnAzaPcs) of the tetrapyrazinoporphyrazine type have been synthesized as potential sensitizers for photodynamic therapy (PDT). Octasubstituted complexes, with thiophen-2-yl, thiophen-3-yl or benzo[b]thiophen-3-yl peripheral groups, were synthesized and characterized. Octa(thiophen-2-yl) ZnAzaPc is a better singlet oxygen producer and has a red shifted UV absorption Q-band compared to both thiophen-3-yl and benzo[b]thiophen-3-yl substituted ZnAzaPcs. Thus, the thiophen-2-yl substituent is better suited for our purpose. Unsymmetrically substituted ZnAzaPcs were synthesized by cyclotetramerisations of pyrazine-2,3-dicarbonitriles attached to one thiophen-2-yl group and one alkylsulfanyl, thiomorpholinyl or imide group. Constitutional isomers were detected by NMR spectroscopy for some of these complexes. Compared to unsubstituted ZnAzaPc, red shifted Q-bands were observed for all these complexes, due to the presence of thiophen-2-yl groups. The least promising complexes are ZnAzaPcs with thiomorpholine or imide peripheral substituents, i.e. where the peripheral substituents are attached to the macrocycle through nitrogen atoms. Low singlet oxygen quantum yields (Φ_Δ) and also low fluorescence quantum yields (Φ_F) were observed for these ZnAzaPcs. In the case of combined thiophen-2-yl and alkylsulfanyl substituents, the values of Φ_Δ were the highest and reached values of approximately 0.69.     

Two mononuclear molybdenum(VI) oxo complexes with tridentate hydrazone ligands: Synthesis and crystal structures

Reaction of [MoO₂(Acac)₂] (Acac = acetylacetonate) with two similar hydrazone ligands in methanol yielded two mononuclear molybdenum(VI) oxocomplexes with general formula [MoO₂(L)(CH₃OH)], where L = L¹ = (4-nitrophenoxy)acetic acid [1-(3-ethoxy-2-hydroxyphenyl)methylidene]hydrazide (H₂L¹) and L = L² = (4-nitrophenoxy)acetic acid [1-(5-bromo-2-hydroxyphenyl)methylidene]hydrazide (H₂L²). Crystal and molecular structures of the complexes were determined by single crystal X-ray diffraction method. All investigated compounds were further characterized by elemental analysis and FT-IR spectra. Single crystal X-ray structural studies indicate that the hydrazone ligands coordinate to the MoO₂ cores through enolate oxygen, phenolate oxygen, and azomethine nitrogen. The Mo atoms in both complexes are in octahedral coordination.     

Two mononuclear molybdenum(VI) oxo complexes with tridentate hydrazone ligands: Synthesis,structures, and thermal stability

A reaction of [MoO₂(acac)₂] (where acac = acetylacetonate) with two hydrazone ligands in methanol yields two mononuclear molybdenum(VI) oxo complexes with the general formula [MoO₂L(CH₃OH)], where L = L¹=(4-nitrophenoxy)acetic acid [1-(5-chloro-2-hydroxyphenyl)methylidene]hydrazide (H₂L¹) and L = L²=4-dimethylaminobenzoic acid [1-(2-hydroxy-3-methoxyphenyl)methylidene]hydrazide (H₂L²). The crystal and molecular structures of the complexes are determined by the single crystal X-ray diffraction method. All of the investigated compounds are further characterized by the elemental analysis, FT-IR spectra, and thermogravimetric analysies. Single crystal X-ray structural studies indicate that hydrazone ligands coordinate to MoO₂ cores through enolate oxygen, phenolate oxygen, and azomethine nitrogen atoms. The Mo atoms in both complexes are in octahedral coordination.     

Study of the interaction between ruthenium(II) complexes and CT-DNA: synthesis,characterisation, photocleavage and antimicrobial activity studies

Two polypyridyl ligands 6-fluro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (FIPC), 6-chloro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (ClIPC) polypyridyl ligands and their Ru(II) complexes [Ru(bipy)₂FIPC]²⁺(1), [Ru(dmb)₂FIPC]²⁺(2), [Ru(phen)₂FIPC]²⁺(3), [Ru(bipy)₂ClIPC]²⁺(4), [Ru(dmb)₂ClIPC]²⁺(5) and [Ru(phen)₂ClIPC]²⁺(6) ((bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesised and characterised by elemental analysis, Mass spectra, IR, ¹H and ¹³C-NMR. The DNA-binding of the six complexes to calf-thymus DNA (CT-DNA) has been investigated by different spectrophotometric, fluorescence and viscosity measurements. The results suggest that 1–6 complexes bind to CT-DNA through intercalation. The variation in binding affinities of these complexes is rationalised by a consideration of electrostatic, steric factors and nature of ancillary ligands. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA. Inhibitor studies suggest that singlet oxygen (¹O₂) plays a significant role in the cleavage mechanism of Ru(II) complexes. Thereby, under comparable experimental conditions [Ru(phen)₂FIPC]²⁺(3), [Ru(phen)₂ClIPC]²⁺(6) cleaves DNA more effectively than 1, 2, 4 and 5 complexes do. The Ru(II) polypyridyl complexes (1–6) have been screened for antimicrobial activities.     

Synthesis,characterization, and DNA-binding of [Co(phen)2(CPIA)]3+, [Co(phen)2(BIP)]3+, and [Co(phen)2(CIP)]3+

Three ligands, 2-(3-(carboxymethyl)-1,10-phenanthroline-[5,6-d]imidazole-1-yl)acetate (CPIA), 2-(benzo[d][1,3]dioxol-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (BIP), and 2-(9H-carbazol-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (CIP), and their complexes, [Co(phen)₂(CPIA)]³⁺ (1) (phen = 1,10-phenanthroline), [Co(phen)₂(BIP)]³⁺ (2), and [Co(phen)₂(CIP)]³⁺ (3), have been synthesized and characterized. Binding of the three complexes with calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods, cyclic voltammetry, and viscosity measurements. The three complexes bind to DNA through an intercalative mode, and the size and shape of the intercalative ligands have significant effects on the binding affinity of complexes to CT-DNA.     

Discovery of New Pyrazolopyridine,Furopyridine, and Pyridine Derivatives as CDK2 Inhibitors: Design,Synthesis, Docking Studies,and Anti-Proliferative Activity

New pyridine, pyrazoloyridine, and furopyridine derivatives substituted with naphthyl and thienyl moieties were designed and synthesized starting from 6-(naphthalen-2-yl)-2-oxo-4-(thiophen-2-yl)-1,2-dihydropyridine-3-carbonitrile (1). The chloro, methoxy, cholroacetoxy, imidazolyl, azide, and arylamino derivatives were prepared to obtain the pyridine-⁻C² functionalized derivatives. The derived pyrazolpyridine-N-glycosides were synthesized via heterocyclization of the C²-thioxopyridine derivative followed by glycosylation using glucose and galactose. The furopyridine derivative 14 and the tricyclic pyrido[3′,2′:4,5]furo[3,2-d]pyrimidine 15 were prepared via heterocyclization of the ester derivative followed by a reaction with formamide. The newly synthesized compounds were evaluated for their ability to in vitro inhibit the CDK2 enzyme. In addition, the cytotoxicity of the compounds was tested against four different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549). The CDK2/cyclin A2 enzyme inhibitory results revealed that pyridone 1, 2-chloro-6-(naphthalen-2-yl)-4-(thiophen-2-yl)nicotinonitrile (4), 6-(naphthalen-2-yl)-4-(thiophen-2-yl)-1H-pyrazolo[3,4-b]pyridin-3-amine (8), S-(3-cyano-6-(naphthaen-2-yl)-4-(thiophen-2-yl)pyridin-2-yl) 2-chloroethanethioate (11), and ethyl 3-amino-6-(naphthalen-2-yl)-4-(thiophen-2-yl)furo[2,3-b]pyridine-2-carboxylate (14) are among the most active inhibitors with IC₅₀ values of 0.57, 0.24, 0.65, 0.50, and 0.93 µM, respectively, compared to roscovitine (IC₅₀ 0.394 μM). Most compounds showed significant inhibition on different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549) with IC₅₀ ranges of 31.3–49.0, 19.3–55.5, 22.7–44.8, and 36.8–70.7 μM, respectively compared to doxorubicin (IC₅₀ 40.0, 64.8, 24.7 and 58.1 µM, respectively). Furthermore, a molecular docking study suggests that most of the target compounds have a similar binding mode as a reference compound in the active site of the CDK2 enzyme. The structural requirements controlling the CDK2 inhibitory activity were determined through the generation of a statistically significant 2D-QSAR model.     

Structural and photophysical studies of triphenylamine-based nonlinear optical dyes: effects of π-linker moieties on the D-π-A structure

In this work, a series of eight metal-free organic dyes based on triphenylamine as a donor and cyanoacetic acid as an acceptor of electrons with the donor-π-acceptor structure were studied by DFT and TD-DFT methods. Their electronic properties, absorption spectra, and molecular nonlinear optical (NLO) responses have been analyzed and reported. The influence of the change of π-conjugated linker on the electrochemical and photophysical properties of these metal-free organic dyes has been investigated and discussed in detail. The energy gap decreases by going from L1 to L8, which causes a large NLO response for the studied dyes. The natural bond orbital (NBO) analysis reveals that the separation of charge occurred upon photoexcitation and the electrons moved from the donor to the acceptor moiety. A high NLO response reveals that this kind of metal-free organic dyes has eye-catching and remarkably large first hyperpolarizability β_tot values, especially for L7 ((E)-2-cyano-3-(3-((E)-2-(3-((E)-4-(diphenylamino)styryl)benzo[c]thiophen-1-yl)vinyl)benzo [c]thiophen-1-yl)acrylic acid) and L8 ((E)-2-cyano-3-(7-((E)-2-(7-((E)-4-(diphenylamino)styryl)thieno[3,4-b]pyrazin-5-yl)vinyl)thieno[3,4-b]pyrazin-5-yl)acrylic acid) with 150423.50 (a.u) and 202773.63 (a.u), respectively. Our research has been carried out to extend the conjugation of organic materials by controlling their π-conjugated linker to design new appealing NLO compounds. This study shows that these dyes are promising and have special properties for modern hi-tech applications such as solar cells, transistors, and organic light-emitting diodes (OLEDs), and even these properties can be adjusted and enhanced by the incorporation of the benzothiophene or thienopyrazine derivatives as a bridge so as to improve from L7 to L8.     

Syntheses, characterization, X-ray crystal structures and emission properties of five oxovanadium(V) complexes with pyridyl/pyrimidyl-pyrazole derived ditopic ligands

Four oxovanadium(V) complexes of heterocycle based ditopic ligands PyPzOAP (N-[amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PyPzOAPz (N-[amino(pyrazin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PymPzOAP (N-[amino(pyridin-2-yl)methylidene]-1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-1H-pyrazole-3-carbohydrazonic acid) and PyPzCAP (5-methyl-1-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) and a binuclear (di-μ-oxo) oxovanadium(V) complex of the ligand PymPzCAP (1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) have been investigated. The ligands act as uninegative NNO tridentates donors for the VO₂⁺ ion exhibiting their monotopicity. The ligands show varying emission properties due to the presence of fluophoric groups like 1-(2-pyridyl)pyrazole or 1-(2-pyrimidyl)pyrazole. The vanadium(V) complexes show fluorescence quenching with respect to the used ligands to a varying extent. The complexes were characterized by UV-Vis, IR, cyclic voltammetry and X-ray crystallography.     

Microwave assisted synthesis of substituted (<Emphasis Type="Italic">Z</Emphasis>)-2-{[1-phenyl-3-(thiophen-2-yl)-1<Emphasis Type="Italic">H</Emphasis>-pyrazol- 4-yl]methylene}benzofuran-3(2<Emphasis Type="Italic">H</Emphasis>)-ones and their antimicrobial activity

Aurones, pyrazole and thiophene scaffolds are known for their potential antimicrobial activity. Herein, we have synthesized hybrid compounds containing three substituted (Z)-2-{[1-phenyl-3-(thiophen-2-yl)- 1H-pyrazol-4-yl]methylene}benzofuran-3(2H)-ones that had been produced from substituted (E)-1-(2-hydroxyphenyl)- 3-[1-phenyl-3-(thiophen-2-yl)-1H-pyrazol-4-yl]prop-2-en-1-ones in high yields. All synthesized compounds were tested in vitro for their antimicrobial activity. Several of those demonstrated promising activity against some fungal and bacterial strains.     

Synthesis,characterization and antioxidant,antibacterial activity Zn2+, Cu2+, Ni2+ and Co2+, complexes of ligand [2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole]

New metal complexes of (Zn(II), Co(II), Ni(II) and Cu(II)) based on the ligand 2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole] were synthesized, whose structures were determined with the different spectroscopic techniques ¹H NMR,¹³C NMR, FT-IR, UV–Visible and by mass spectrometry. The thermal analysis was performed by TG-DTA. The antioxidant activity of the ligand and its complexes was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) method, in comparison with the synthetic antioxidant, ascorbic acid. The results obtained showed that the antioxidant activity of the ligand and its complexes is moderate and that the copper complex has a high activity that exceeds that of ascorbic acid. Antimicrobial activity of the ligand and its metal complexes was studied against two Gram-positive bacteria: Bacillus subtilis ILP1428B, Staphylococcus aureus CIP543154 and two Gram-negative bacteria: Pseudomonas aeruginosa ATCC27653, Escherichia coli CIP5412 (American Type Culture Collection)the activity data show that the metal complexes are more potent than the free ligand.     

Solution Equilibria of Ternary Systems Involving Nickel(II) Ion,Picolinic Acid,and the Amino Acids Histidine,Cysteine, Aspartic and Glutamic Acids

Solution equilibria of the ternary systems Ni(II)–picolinic acid (Hpic) and the amino acids aspartic acid (H₂asp), glutamic acid (H₂glu), cysteine (H₂cys) and histidine (Hhis), where the amino acids are denoted as H _i L, have been studied pH-metrically. The formation constants of the resulting mixed ligand complexes have been determined at 25 °C using a ionic strength 1.0 mol·dm^?3 NaCl. In the Ni(II)–Hpic–H₂asp and Ni(II)–Hpic–H₂glu systems, the complexes [Ni(pic)H₂L]⁺, Ni(pic)HL, [Ni(pic)L]^? and [Ni(pic)L(OH)]^2? were detected. In the Ni(II)–Hpic–H₂cys system the complexes [Ni(pic)H₂L]⁺ and [Ni(pic)L]^? are present. Additionally, in the Ni(II)–Hpic–Hhis system the species [Ni(Hpic)HL]²⁺, Ni(pic)L and [Ni(pic)L(OH)]^? were identified. The species distribution diagrams as functions of pH are briefly discussed.     

Lanthanide Complexes of Polyacid Ligands derived from 2, 6-bis(pyrazol-1-yl)pyridine,pyrazine, and 6, 6′-bis(pyrazol-1-yl)-2, 2′-bipyridine: Synthesis and luminescence properties

The synthesis of three novel pyrazole-containing complexing acids, N,N,N′,N′-{2, 6-bis[3-(aminomethyl)pyrazol-1-yl]-4-methoxypyridine}tetrakis(acetic acid)( 1 ), N,N,N′,N′-{2, 6-bis[3-(aminomethyl)pyrazol-1-yl]pyrazine}-tetrakis(acetic acid) ( 2 ), and N,N,N′,N′-{6, 6′-bis[3-(aminomethyl)pyrazol-1-yl]-2, 2′-bipyridine}tetrakis(acetic acid) ( 3 ) is described. Ligands 1–3 formed stable complexes with Eu^III, Tb^III, Sm^III, and Dy^III in H₂O whose relative luminescence yields, triplet-state energies, and emission decay lifetimes were measured. The number of H₂O molecules in the first coordination sphere of the lanthanide ion were also determined. Comparison of data from the Eu^III and Tb^III complexes of 1–3 and those of the parent trisheterocycle N,N,N′,N′-{2, 6-bis[3-(aminomethyl)pyrazol-l-yl]pyridine}tetrakis(acetic acid) showed that the modification of the pyridine ring for pyrazine or 2, 2′-bipyridine strongly modify the luminescence properties of the complexes. MeO Substitution at C(4) of 1 maintain the excellent properties described for the parent compound and give an additional functional group that will serve for attaching the label to biomolecules in bioaffinity applications.     

Substituent effect of fluorine atom on benzothiadiazole bridging unit in dye sensitized solar cells

Dye sensitized solar cells performances using two organic dyes with fluorinated-benzothiadiazole spacer, 3-{5-[7-(5-{4-[Bis(9,9-dimethyl-9H-fluoren-2-yl)-amino]-5-fluoro-phenyl}thiophen-2-yl)benzo-[1,2,5]thiadiazol-4-yl]thiophen-2-yl}-2-cyano acrylic acid (JK-311) and 3-{5-[7-(5-{4-[Bis(9,9-dimethyl-9H-fluoren-2-yl)-amino]-5,6-difluorophe-nyl}thiophen-2-yl)benzo-[1,2,5]thiadiazol-4-yl]thiophen-2-yl}-2-cyano acrylic acid (JK-312), were systematically investigated by solar simulation equipment, stepped light-induced transient measurements of photocurrent and voltage, and electrochemical impedance spectroscopy. To investigate substituent effect of fluorine atom on benzothiadiazole, molecular orbital calculations of two dyes using a time dependent density functional theory model with B3LYP/3-31G* were also carried out. JK-312 showed a unique electronic transition from HOMO-1 to LUMO. Short circuit current and open-circuit voltage in DSSCs performances were increased by the introduction of fluorine atom into spacer segment, compared to fluorine-free dyes.     

Synthesis,studies and in vitro antibacterial activity of some 5-(thiophene-2-yl)-phenyl pyrazoline derivatives

In the present investigation, a novel series of pyrazolines 2a–2d were synthesized by the cyclization of various -1-[2-(alkoxy) phenyl]-3-(thiophen-2-yl) prop-2-en-1-one 1a–1d with N-substituted phenyl hydrazine and thiosemicarbazide in the presence of CH₃COOH and NaOH in ethanol which lead to the formation of new pyrazolines. The structures of these compounds were elucidated by, IR, ¹H-NMR, ¹³C-NMR, ESI-MS spectral data and their purities were confirmed by elemental analyes. The in vitro antibacterial activity of these compounds was evaluated against two Gram-positive and two Gram-negative bacteria Aeromonas hydrophila, Yersinia enterocolitica, Listeria monocytogenes, and Staphylococcus aureus by microdilution method and then the minimum inhibitory concentration (MIC) of these compounds was determined. The results showed that compounds 1-[2-(benzyloxy) phenyl]-5-(thiophen-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl (2b) and 1-[2-(naphthalen-2-ylmethoxy) phenyl]-5-(thiophene-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole-4-yl (2d) showed most promising antibacterial activity as compared to the antibiotics gentamicin and tetracycline in (Table 1, Table 2).     

Efficient enantiorecognition of ruthenium(II) complexes by silica-bound teicoplanin

A series of chiral tris-diimine ruthenium(II) complexes have been resolved by HPLC on a chiral stationary phase. The stationary phase (CSP1) was prepared by covalent attachment of the glycopeptide antibiotic teicoplanin to isocyanate activated silica gel. CSP1 selectively retains the enantiomers of [Ru(L)₃]²⁺ (L=2,2′-bypyridine (bpy), 1,10-phenanthroline and 4,7-diphenyl-1,10-phenanthroline), with a preference for the Δ isomer. For the mixed-ligand complexes [Ru(bpy)₂pztr]⁺ and [Ru(bpy)₂pytr]⁺ (Hpztr=3-(pyrazin-2-yl)-1,2,4-triazole, Hpytr=3-(pyridin-2-yl)-1,2,4-triazole), where the triazole unit is bound to the metal centre either through the N² or the N⁴ nitrogen of the ring, CSP1 discriminates both the enantiomers and the regioisomers. Diastereo- and enantioselective association was also observed between CSP1 and the stereoisomers of the dinuclear complex ((Ru(bpy)₂)₂bpt]³⁺ (Hbpt=3,5-bis(pyridin-2-yl)-1,2,4-triazole), with differences in binding affinities of 1.4 kJ/mol between the homochiral enantiomers.