Enamines of 1,3-dimethylbarbiturates and their symmetrical palladium(II) complexes: synthesis,characterization and biological activity

Transition Metal Chemistry - Three 1,3-dimethylbarbiturate-enamine derivatives and their symmetrical palladium(II) complexes were prepared and characterized by spectroscopic methods. In addition,...     

Selfadjoint extensions of a singular differential operator

In this work, firstly in the Hilbert space of vector-functions all selfadjoint extensions of the minimal operator generated by linear singular symmetric differential expression with a selfadjoint operator coefficient A in any Hilbert space H, are described in terms of boundary values. Later structure of the spectrum of these extensions is investigated.     

A novel bidentate ligand containing oxime,hydrazone and indole moieties and its BF2+ bridged transition metal complexes and their efficiency against prostate and breast cancer cells

In this study, a novel bidentate ligand containing oxime, hydrazone, and indole moieties and its BF₂⁺-bridged transition metal complexes [Ni(II), Cu(II), and Co(II)] were synthesized and their cytotoxic activities against prostate and breast cancer cells were investigated. The vic-dioxime ligand bearing indole–hydrazone side groups was synthesized by reacting antiglyoximehydrazine (GH₂) with 3-methoxy indole. The ligand forms mononuclear complexes with a metal-to-ligand ratio of 1:2 with M = Co(II)(H₂O)₂, Ni(II), and Cu(II). These metal complexes were then reacted with BF₃(C₂H₅)₂O to obtain BF₂⁺-bridged transition metal complexes. The Co(II) complex of the ligand is proposed to be octahedral with water molecules as axial ligands, whereas the Ni(II) and Cu(II) complexes are proposed to be square planar. Spectral studies showed that the ligand bonded to the metal ion in a neutral bidentate fashion through the azomethine nitrogen atom and the imine oxime group. Structural assignments are supported by a combination of ¹H nuclear magnetic resonance (NMR), ¹³C NMR, Fourier-transform infrared, LC/MS, elemental analyses, and magnetic susceptibility testing. For determining the cytotoxic effects of the novel anticancer products, cancer cells were cultured. The antiproliferative effects were determined using the MCF-7 breast cancer and PC-3 prostate cancer cell lines. The antiproliferative effects of the products were analyzed and their apoptotic or necrotic effects were determined with the Hoechst/propidium iodide double staining method in both cancer cell lines. Paclitaxel was used as the positive control (1 μm ). The results indicated that the newly synthesized compounds are effective on both cell lines between concentrations of 5 and 40 μm and show their effects by apoptotic mechanisms. Besides, these products were found to be more effective on the MCF-7 cell line. The cytotoxic efficiency of the newly synthesized products was more than that of paclitaxel (depending on concentration), which is a chemotherapeutic agent used in cancer therapy.     

In Situ Electrochemical Production of Metal-organic Hybrid Composite Film from Nickel Containing Polyoxometalate and 3,4-Ethylenedioxy-thiophene for Sensor Application

In situ electrochemical synthesis of an organic-inorganic hybrid material composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and nickel-based Keggin type polyoxometalate, K₇[Ni^IIINi^II(H₂O)W₁₁O₃₉].15H₂O(NiPOM), has been proposed here. The remarkable optical and electrical properties of the PEDOT and the unique redox properties of NiPOM have synergistically combined to make the hybrid structure highly desired multi-functional materials for a myriad of applications. The driving force for the formation of hybrid structure is thought to be electrostatic interactions between POM anions and cationic polaron/bipolaron structures that in the PEDOT. PEDOT/NiPOM based hybrid composite modified graphite electrode has been used for non-enzymatic glucose sensor platform as a sample of applications. Furthermore, PEDOT/NiPOM based sensor platform was successfully utilized for detection of glucose content with the lowest detection limit in real samples like honey and milk. These results suggest that PEDOT/NiPOM metal-organic hybrid composite could be utilized as multi-functional material for a myriad of applications.     

New palladium(II)–N‐heterocyclic carbene complexes containing benzimidazole‐2‐ylidene ligand derived from menthol: synthesis,characterization and catalytic activities

A new series of sterically hindered ligands containing (1R,2S,4R)‐(+)‐menthoxymethyl group attached to benzimidazole‐based N‐heterocyclic carbene (NHC), palladium–bis‐NHC complexes and (κ²‐C,N)‐palladacyclic NHC complexes have been synthesized and characterized using appropriate spectroscopic techniques. Catalytic performance of the palladium complexes has been investigated for allylic alkylation, Suzuki and Heck carbon–carbon coupling reactions. These complexes smoothly catalyse the carbon–carbon bond formation reactions. Copyright © 2016 John Wiley & Sons, Ltd.     

Potential N‐Heterocyclic Carbene Precursors in the Palladium‐Catalyzed Heck Reaction

A novel 1‐(cyclobutylmethyl)‐substi‐tuted imidazolidinium/benzimidazolium salts as N‐heterocyclic carbene (NHC) precursors were successfully synthesized and characterized by ¹H NMR, ¹³C NMR, IR, and elemental analysis techniques. These compounds were easily prepared from the reaction of N‐alkyl imidazoline/N‐alkyl benzimidazole with bromomethylcyclobutane in high yields. The in situ formed catalytic system derived from the NHC precursor and Pd(OAc)₂ was used in the Heck reaction between aryl halides and styrene with potassium hydroxide in water. The corresponding Heck products were obtained in good yields. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:77–83, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21065     

Bicyclic N-heterocyclic carbene (NHC) ligand precursors and their palladium complexes

Eight bicyclic amidinium precursors (3), prepared from R,S-tmcp (R,S-tmcp: (1R,3S)-diamino-1,2,2-trimethylcyclopentane) were described. Only five of the precursors (3a–e) could be converted to palladium complexes, (PdX₂(6,7-NHC)PEPPSI) (4) by treatment with PdCl₂, K₂CO₃, and pyridine (additional KBr was used for (PdBr₂(6,7-NHC)PEPPSI)). The salts and complexes were fully characterized by spectroscopic methods and X-ray crystallography.     

Synthesis,characterization and catalytic activity in Suzuki–Miyaura coupling of palladacycle complexes with n‐butyl‐substituted N‐heterocyclic carbene ligands

A series of monomeric palladacycle complexes bearing n‐butyl‐substituted N‐heterocyclic carbenes, namely [Pd(NHC)X(dmba)] (dmba: dimethylbenzylamine and [Pd(NHC)X(ppy)]; NHC: 1‐n‐butyl‐3‐substituted benzylimidazol‐2‐ylidene; ppy: 2‐phenylpyridine), were prepared either by transmetallation from the corresponding silver carbene complexes or by the reaction of the corresponding acetate‐bridged palladacycle dimer with N‐heterocyclic carbene ligands in high yields. The palladium(II) complexes were characterized using elemental analyses, APCI‐MS, ¹H NMR and ¹³C NMR spectroscopies. These complexes are efficient in the Suzuki–Miyaura coupling reaction between phenylboronic acid and aryl bromides.     

Middle school students’ proportional reasoning in real life contexts in the domain of geometry and measurement

The purpose of this study was to examine middle school students’ proportional reasoning, solution strategies and difficulties in real life contexts in the domain of geometry and measurement. The underlying reasons of the difficulties were investigated as well. Mixed research design was adopted for the aims of the study by collecting data through an achievement test from 935 sixth, seventh and eighth grade students. The achievement test included real life problems that required proportional reasoning, and were related to the measurement of length, perimeter, area and volume concepts. In addition, task-based interviews were conducted on 12 of these students to collect more comprehensive data and to support the findings of the achievement test. Findings revealed that although students were mostly successful in giving correct answers, their reasoning lacked a clear argument of the direct and indirect proportional relationships between the variables and that they approached the problems by superficial characteristics of the problems.