排序方式: 共有82条查询结果,搜索用时 608 毫秒
11.
Mansoor Ahmed Qazi Ümmühan Ocak Miraç Ocak Shahabuddin Memon Imam Bakhsh Solangi 《Journal of fluorescence》2013,23(3):575-590
A readily available chromionophore 5,11,17,23-tetra-tert-butyl-25,27-bis(hydrazidecarbonylmethoxy)-26,28-dihydroxycalix[4]arene (HCC4) was employed as a chromogenic sensing probe selective for Pb(II) and Cr2O7 2? ions among a series of various ions such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) as well as Cr2O7 2?, CH3CO2 ?, Br?, Cl?, F?, I?, ClO4 ? and NO3 ? that have been examined by UV-visible and fluorescence spectroscopic techniques. The HCC4 in DCM-MeCN system forms 2:1 (ligand-metal) complex with Pb(II). It also shows 2:1 stoichiometry with Cr2O7 2?. The complexation phenomenon has been confirmed by FTIR spectroscopy that favors the selective nature of HCC4 with Pb(II) and Cr2O7 2?. Thermal gravimetric analysis (TGA) also supports its utility in drastic conditions. 相似文献
12.
Nuran Kahriman Serhat Gün Abidin Gümrüküolu Nurettin Yayl Ümmühan Ocak Mira Ocak 《Journal of heterocyclic chemistry》2019,56(9):2612-2618
Anion sensor properties of N‐alkyl‐substituted 1,4′‐diazaflavonium bromides in methanol–water were evaluated by UV–vis spectrometry. Pronounced changes were observed in the absorption spectra of all compounds for only OH?, CO32?, and CN? among F?, Cl?, Br?, I?, OH?, CO32?, NO3?, PO43?, CN?, SO42?, HSO4?, HCO3?, SCN?, NO2?, and P2O72? ions. Two new absorption bands at 385 and 685 nm accompanying the distinct color change for OH?, CO32?, and CN? ions were observed in case of all compounds. The color changes were from pink to blue for CO32? and OH? ions and from pink to purple for CN? ion. Thanks to the distinct color change, the compounds can be used as selective colorimetric anion sensors. Linear changes of absorbance of N‐heptyl‐substituted compound at 385 nm as a function of the ion concentration were used to determine CN? ion in water samples. Detection and quantification limits of the proposed method were 0.94 and 2.82 mg/L, respectively. 相似文献
13.
Electrical and photoelectrical behaviour of heterojunctions based on novel oligomeric metal complexes 下载免费PDF全文
Metin Atlan Yusuf Selim Ocak Salih Pasa Hamdi Temel Ahmet Tombak Tahsin Kilicoğlu Kemal Akkilic Murat Aydemir 《应用有机金属化学》2015,29(12):798-804
Naringenin‐based Schiff base ligands with 4‐aminobenzoic hydrazide were obtained as a unilateral form ( L1 ). The ligand was oligomerized by oxidative polycondensation reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90 °C to form a functional oligomer ( L2 ), and its transition metal complexes such as those with Cu(II), Ni(II) and Zn(II) were prepared. The monomer and the oligomeric compounds were characterized using various techniques. Optical and electrical properties of the complexes were also investigated. All compounds showed indirect band gaps and they can be accepted as being in the semiconductor class. Organic–inorganic hybrid devices were obtained using n‐Si inorganic semiconductor and the complexes. The characteristic parameters of the devices were determined using current–voltage (I–V) and capacitance–voltage measurements in the dark. Photoelectrical properties of the devices were investigated using I–V measurements under a solar simulator with an AM1.5 global filter. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
14.
Miraç Ocak Nurhan Gümrükçüoğlu Ümmühan Ocak Hans-Jurgen Buschmann Eckard Schollmeyer 《Journal of solution chemistry》2008,37(11):1489-1497
Six new triazole compounds were synthesized. These compounds containing the substituted benzylidenamino group were obtained
by reaction of 3-(pyridine-4-yl)-5-p-tolyl-4-amino-4H-l,2,4-triazole 1 with the corresponding aldehyde. The reduced forms were prepared with NaBH4 in methanol. The structures of the compounds were determined by IR, 1H NMR, and 13C NMR spectral data, and their interaction with cations such as Li+, Na+, K+, Rb+, Cs+, Ba2+, Sr2+, Ca2+, Cu2+, Cr3+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+ and Ag+ were investigated by using UV-visible spectrophotometry. Of the tested metal cations, Cu2+, Cr3+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+ and Ag+ complexed with the ligands. The complex stability constants (log 10
K) were measured in slightly acidic aqueous media at 25.0±0.1 °C. These stability constants were determined by measuring the
increase in solubility of the nearly insoluble ligand molecule due to complex formation with a soluble cation, and this method
is discussed. It was found that the position of chlorine atoms on the benzene ring strongly affects the complexation of Cu2+ ion with these ligands. 相似文献
15.
Shahabuddin Memon Ashfaque Ali Bhatti Asif Ali Bhatti Ümmühan Ocak Miraç Ocak 《Journal of the Iranian Chemical Society》2016,13(12):2275-2282
This article reports the selective sensing ability of a newly synthesized calix[4]arene Schiff base (C4TSB) derivative. C4TSB exhibited strong turn-off fluorescence affinity for Hg2+ and Au3+. The selective sensing ability of receptor was investigated in the presence of different co-existing competing ions. The limit of detection for Hg2+ and Au3+ was determined as 1.9 × 10?5 and 1.0 × 10?6 M, respectively. Receptor forms 1:1 stoichiometric complex with both metals and their binding constants were calculated as 7.9 × 103 M?1 for Hg2+ and 5.7 × 103 M?1 for Au3+. Complexes were also characterized through FT-IR spectroscopy. 相似文献
16.
Nazan Ocak Ískeleli amil Ik Kemal Sancak Selami amaz Yasemin Ünver Mustafa Er 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o363-o365
The title compounds, C12H20N6O2, (I), and C5H9N3O2, (II), display the characteristic features of 1,2,4‐triazole derivatives. Compound (I) lies about an inversion centre which is at the mid‐point of the central C—C bond. Compound (II) also contains a planar 1,2,4‐triazole ring but differs from (I) in that it has a hydroxy group attached to the ring. Molecules of (I) are held together in the crystal structure by intermolecular N—H⋯O contacts and by weak π–π stacking interactions between the 1,2,4‐triazole moieties. Compound (II) contains intermolecular O—H⋯O and N—H⋯O hydrogen bonds. 相似文献
17.
Hasan Karabıyık Hande Petek Nazan Ocak İskeleli Çiğdem Albayrak 《Structural chemistry》2009,20(6):1055-1065
The molecular and crystal structure of (Z)-6-((4-bromophenylamino)methylene)-2,3-dihydroxycyclohexa-2,4-dienone were determined by single crystal X-ray diffraction
and spectroscopic methods. Molecules of the compound can be regarded as a resonance hybrid of cis-keto tautomer and zwitterionic form. Pairs of molecules of the compound generate pseudocyclic centrosymmetric R22 (10) R_{2}^{2} (10) supramolecular synthons with the aid of O–H···O type intermolecular H-bonds. Stacking of R22 (10) R_{2}^{2} (10) synthons along b-axis is stabilized by π···π interactions. Changes in both covalent topology and molecular geometry of the compound accompanying
proton transfer were monitored by a relaxed PES scan with respect to hydroxyl bond length used as redundant internal coordinate.
Quantum chemical studies at 6-311 + G(d,p) level reveal that bond lengths which are indicative to tautomerization process
cannot reach their expected values even if proton transfer occurs in gas phase and pseudo-aromatic chelate ring formation
has primary effect on the stabilization of NH tautomer. Resonance-assisted intramolecular H-bond affects the electronic state
of its neighboring aromatic fragments. 相似文献
18.
M. Emin Özdemir Ahmet Ocak Akdemir Çetin Yıldız 《Czechoslovak Mathematical Journal》2012,62(4):889-900
A function f: I → ?, where I ? ? is an interval, is said to be a convex function on I if $$f(tx + (1 - t)y) \le tf(x) + (1 - t)f(y)$$ holds for all x, y ∈ I and t ∈ [0, 1]. There are several papers in the literature which discuss properties of convexity and contain integral inequalities. Furthermore, new classes of convex functions have been introduced in order to generalize the results and to obtain new estimations. We define some new classes of convex functions that we name quasi-convex, Jensenconvex, Wright-convex, Jensen-quasi-convex and Wright-quasi-convex functions on the coordinates. We also prove some inequalities of Hadamard-type as Dragomir’s results in Theorem 5, but now for Jensen-quasi-convex and Wright-quasi-convex functions. Finally, we give some inclusions which clarify the relationship between these new classes of functions. 相似文献
19.
Yasemin ?a?lar Nurhan Gümrük?üo?lu Ece Tu?ba Saka Mira? Ocak Halit Kantekin ümmühan Ocak 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(3-4):443-447
A tetra-substituted phthalocyanine based on 4-[2-(4-nitrophenoxy)ethoxy]phthalonitrile carrying nitrophenyl group for the sensing of Zn2+ has been prepared and characterized by elemental analysis, FT-IR, 1H and 13C NMR, and MS spectral data. The sensing of Zn2+ is based on the fluorescence quenching of Pc. Both absorbance and fluorescence spectra of ZnPc exhibit distinct changes in visible region in response to treatment with Zn2+ ion in dimethyl sulfoxide. The fluorescence spectrum of the ligand showed quenching in the intensity of the signal at 688?nm for Zn2+. The complex composition of ZnPc was found 1:1 by means of spectrophotometric and spectrofluorimetric titration data. The spectrofluorimetric method showed good sensitivity for Zn2+ with linear range and detection limit of 4.0?×?10?6–4.4?×?10?5 and 2.4×10?7?M, respectively. 相似文献
20.
M. Yıldız H. Ünver D. Erdener N. Ocak A. Erdönmez T. Nuri Durlu 《Crystal Research and Technology》2006,41(6):600-606
The title compound has been synthesised by the reaction of 2-hydroxy-1-naphthaldehyde with 2,5-dichloroaniline. The compound was characterized by elemental analysis, IR and UV-Visible techniques. The UV-Visible spectra of the Schiff base with OH group in ortho position to the imino group was studied in polar and nonpolar solvents in acidic and basic media. The structure of compound has been examined cyrstallographically. It crystallizes in the orthorhombic space group P212121 with a = 6.059(1), b = 12.105(2) c = 20.006(2) Å, V = 1467.4(3) Å3, Dx = 1.431 g.cm-3 and Z = 4. The crystal structure was solved by direct methods and refined by full-matrix least squares. Molecule of the title compound N-[2-hydroxy-1-naphthylidene]2,5-dichloroaniline is nearly planar. The molecule contains a strong intramolecular N…H-O hydrogen bond between the imine and hydroxyl group [O1 and N1 = 2.540(4) Å]. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献