Attractive versus Repulsive Excitonic Interactions of Colloidal Quantum Dots Control Blue- to Red-Shifting (and Non-shifting) Amplified Spontaneous Emission

Tunable, high-performance, two-photon absorption (TPA)-based amplified spontaneous emission (ASE) from near-unity quantum efficiency colloidal quantum dots (CQDs) is reported. Besides the absolute spectral tuning of ASE, the relative spectral tuning of ASE peak with respect to spontaneous emission was shown through engineering excitonic interactions in quasi-type-II CdSe/CdS core/shell CQDs. With core shell size adjustments, it was revealed that Coulombic exciton-exciton interactions can be tuned to be attractive (type-I-like) or repulsive (type-II-like) leading to red- or blue-shifted ASE peak, respectively, and that nonshifting ASE can be achieved with the right core shell combinations. The possibility of obtaining ASE at a specific wavelength from both type-I-like and type-II-like CQDs was also demonstrated. The experimental observations were supported by parametric quantum-mechanical modeling, shedding light on the type-tunability. These excitonically engineered CQD-solids exhibited TPA-based ASE threshold as low as 6.5 mJ/cm(2) under 800 nm excitation, displaying one of the highest values of TPA cross-section of 44 660 GM

Palandöken Dağının Atmosferik Özellikleri

Erzurum şehir merkezine çok yakın bir konumda olan Palandöken Dağı, 3175 m yüksekliğiyle Türkiye’deki ve Dünya’daki en önemli (stratejik, sportif, turistik vb.) zirvelerden birisidir. Palandöken Dağı ve çevresinin fiziki, stratejik ve atmosferik koşullarının farklı amaçlarla kullanılabilirliğinin (alternatif enerji kaynakları potansiyelinin belirlenmesi ve enerji üretimi ve teknolojileri, turistik ve sportif faaliyetlerde, kar - su hidrolojisi, bilimsel alanlarda vb.) artırılması, bölgenin ve zirvenin atmosferik haritasının tam olarak çıkarılması ve ayrıca 2011 yılında Erzurum Palandöken Dağı ve çevresinde yapılacak olan Üniversite Kış Oyunları içinde gereken, zirve ve çevresinin temel meteorolojik özelliklerinin ayrıntılı olarak ortaya çıkarılması amacıyla bir bilimsel araştırma projesi kapsamında, yaklaşık 1 yıldır meteorolojik veriler sürekli kaydedilmekte ve incelenmektedir. Bu bilgiler, Bölge Meteoroloji Müdürlüğü’nden alınan meteorolojik yer ve radyosonda verileriyle de karşılaştırılmaktadır. Bu proje kapsamına, yeni başlatılan atmosferik görüş gözlemleri de dahil edilmiştir. Ayrıca bu çalışma ve sonuçları sayesinde, Palandöken Dağı ve çevresindeki yakın zirvelerinde (> 3000 m) meteorolojik özellikleri belirleneceği gibi, yeni yapılmaya başlayan ve devam edecek olan atmosferik ve astronomik diğer testler ile bölgenin temel astronomik özellikleriyle birlikte astronomi konusundaki potansiyeli de ortaya çıkarılmış olacaktır. Bu çalışma, Atatürk Üniversitesi, FenEdebiyat Fakültesi, Fizik Bölümü tarafından yürütülmekte (2007-2008) ve Atatürk Üniversitesi tarafından Bilimsel Araştırma Projesi (BAP - 2007/33) olarak desteklenmektedir

Synthesis and crystal structures of novel copper(II) complexes with glycine and substituted phenanthrolines: reactivity towards DNA/BSA and in vitro cytotoxic and antimicrobial evaluation

New copper(II) complexes-dimeric-[Cu(nphen)(gly)(H2O)](+) (1) and [Cu(dmphen)(gly)(NO3)(H2O)] (2) (nphen = 5-nitro-1,10-phenanthroline, dmphen = 4,7-dimethyl-1,10-phenanthroline, and gly = glycine)-have been synthesized and characterized by CHN analysis, single-crystal X-ray diffraction techniques, FTIR, EPR spectroscopy, and cyclic voltammetry. The CT-DNA-binding properties of these complexes have been investigated by thermal denaturation measurements and both absorption and emission spectroscopy. The DNA cleavage activity of these complexes has been studied on supercoiled pUC19 plasmid DNA by gel electrophoresis experiments in the absence and presence of H2O2. Furthermore, the interaction of these complexes with bovine serum albumin (BSA) has been investigated using absorption and emission spectroscopy. The thermodynamic parameters, free-energy change (Delta G), enthalpy change (Delta H), and entropy change (Delta S) for BSA + complexes 1 and 2 systems have been calculated by the van't Hoff equation at three different temperatures (293.2, 303.2, and 310.2 K). The distance between the BSA and these complexes has been determined using fluorescence resonance energy transfer (FRET). Conformational changes of BSA have been observed using the synchronous fluorescence technique. In addition, in vitro cytotoxicities of these complexes on tumor cell lines (Caco-2, A549, and MCF-7) and healthy cells (BEAS-2B) have been examined. The antimicrobial activity of the complexes has also been tested on certain bacteria cells. The effect of mono and dimeric in the above complexes is presented and discussed. New copper(II) complexes-dimeric-[Cu(nphen)(gly)(H2O)](+) (1) and [Cu(dmphen)(gly) (NO3)(H2O)] (2) (nphen = 5-nitro-1,10-phenanthroline, dmphen = 4,7-dimethyl-1,10-phenanthroline and gly = glycine)-have been synthesized and characterized by CHN analysis, single-crystal X-ray diffraction techniques, FTIR and EPR spectroscopy. They have been tested for their in vitro DNA/BSA interactions by the spectroscopic methods. These complexes exhibited higher cytotoxic and antimicrobial activities. Complex 1 shows better DNA / BSA interactions in comparison to complex 2

Synthesis and characterization of new heterometallic cyanido complexes based on [Co(CN)(6)](3-) building blocks: crystal structure of [Cu-2(N-bishydeten)(2)Co(CN)(6)]center dot 3H(2)O having a strong antiferromagnetic exchange

SOYLU, SERKAN M/0000-0002-8440-1260WOS: 000343922800038A tetradentate N- and O-donor, N,N-bis(2-hydroxyethyl)-ethylenediamine, (N-bishydeten), has been employed to synthesize four new heterometallic cyanido complexes, [Ni-2(N-bishydeten)(2)Co(CN)(6)]center dot 3H(2)O (C1), [Cu-2(N-bishydeten)(2)Co(CN)(6)]center dot 3H(2)O (C2), [Zn-2(N-bishydeten)(2)Co(CN)(6)]center dot 5H(2)O (C3) and K[Cd(N-bishydeten)-Co(CN)(6)]center dot 1.5H(2)O (C4). Characterization of the complexes was performed using IR and EPR spectroscopy (for C2), thermal analysis and elemental analysis techniques. The crystal structure of C2 was determined by the X-ray single crystal diffraction technique. The asymmetric unit of C2 consists of cyanido-bridged trinuclear Cu1Cu2Co3 units {-CN-Cu1(N-bishydeten)-mu-O-Cu2(N-bishydeten)-NC-Co3(CN)(4)-CN-} and three water molecules. The water molecules are situated in the inter-fragment spaces. The [Cu-2(N-bishydeten)(2)](2+) cations are linked to the [Co(CN)(6)](3-) anions via two cyanido bridges to give a 1D neutral zigzag chain. One of two N-bishydeten cations bridges five coordinated Cu1 and six coordinated Cu2 through deprotonated eta(1)-O2 and the charge of C2 is counterbalanced by this eta(1)-O2. The IR spectrum of C2 is quite different from other complexes, three nu(C N) absorption bands were observed due to different cyanido groups in its structure. The thermal decomposition of C1-C4 is processed in multistages. Variable temperature magnetic susceptibility measurement recorded in the 10-300 K range showed the presence of a strong antiferromagnetic exchange interaction in C2 between Cu1 and Cu2 by eta(1)-O2.Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TBAG-104T205]; Gaziosmanpasa University Research FoundationGazi UniversityGaziosmanpasa University [2010/110]The authors thank the Scientific and Technical Research Council of Turkey (TUBITAK, Grant TBAG-104T205) and the Gaziosmanpasa University Research Foundation (Grant 2010/110) for financial support

Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties of manganese (II) complex of picolinate: A combined experimental and computational study

A novel manganese (II) complex with picolinic acid (pyridine 2-carboxylic acid, Hpic), namely, [Mn(pi-c)(2)(H2O)(2)] was prepared and its crystal structure was fully characterized by using single crystal X-ray diffraction. Picolinate (plc) ligands were coordinated to the central manganese(II) ion as bidentate N,O-donors through the nitrogen atoms of pyridine rings and the oxygen atoms of carboxylate groups forming five-membered chelate rings. The spectroscopic characterization of Mn(II) complex was performed by the applications of FT-IR, Raman, UV-vis and EPR techniques. In order to support these studies, density functional theory (DFT) calculations were carried out by using B3LYP level. IR and Raman spectra were simulated at B3LYP level, and obtained results indicated that DFT calculations generally give compatible results to the experimental ones. The electronic structure of the Mn(II) complex was predicted using time dependent DFT (TD-DFT) method with polarizable continuum model (PCM). Molecular stability, hyperconjugative interactions, intramolecular charge transfer (ICT) and bond strength were investigated by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of Mn(II) complex were investigated by the determining of molecular polarizability (alpha) and hyperpolarizability (beta) parameters. (C) 2015 Elsevier B.V. All rights reserved

Synthesis, X-ray structure, spectroscopic characterization and nonlinear optical properties of triaqua(1,10-phenanthroline-2,9-dicarboxylato)manganese(II) dihydrate: A combined experimental and theoretical study

The triaqua(1,10-phenanthroline-2,9-dicarboxylato)manganese(II) dihydrate complex was prepared and its crystal structure was determined by using single crystal X-ray diffraction. Its structure was also characterized by the applying of F1'-IR, Raman and UV-vis spectroscopies. The manganese(II) ion was located to center of distorted pentagonal-bipyramidal geometry. Electron paramagnetic resonance (EPR) measurement was carried out on the Mn(II) complex. In order to support experimental results, density functional theory calculations were performed at HSEH1PBE level and LanL2DZ basis set. Obtained results indicated that theoretical results can replace the experimental ones. The relatively active nu(CO) nu(CC) and nu(CN) stretching vibration peaks appeared in IR and Raman spectra of complex 1 which are indicators of charge transfer within complex 1 suggest that complex 1 is a good candidate for nonlinear optical materials. The HOMO and LUMO energies determined that complex 1 is stable and the charge transfer occurs within complex 1. (C) 2015 Elsevier B.V. All rights reserved

From Metalloligand to Extended 3D Network: Synthesis, Crystal Structure and Magnetic Property of {[Cu(en)(2)][Cu(mu(3)-pydc)(2)]center dot 6H(2)O} (n)

A novel 2D coordination polymer, {[Cu(en)(2)][Cu(mu(3)-pydc)(2)]center dot 6H(2)O} (n) (1) pyridine-2,3-dicarboxylic acid (pydcH(2)); ethylenediamine (en), based on the metalloligand [Cu(mu-pydcH)(2)] (n) , has been prepared and characterized by IR, UV-Vis and ESR spectroscopy, thermal analysis, differential scanning calorimetry and single crystal X-ray diffraction techniques. The temperature dependent magnetic properties have also been studied. The pydc ligand exhibits tetradentate-mu(3) bridging mode, being coordinated through three carboxylate oxygens and one nitrogen atom. The complex contains two copper(II) ions that exhibit two different coordination environment with two en and two pydc ligands. The single crystal structure shows that the complex forms a 3D framework with 2D layers along the c-axis. Van der Waals interactions are responsible for the self-assembly of the layer into a 3D network.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109T201]This work has been supported by The Scientific and Technological Research Council of Turkey (TUBITAK, No: 109T201).WOS:0002908016000072-s2.0-7995745628

-Based Organic Hybrid Solar Cells with Doping

A hybrid solar cell is designed and proposed as a feasible and reasonable alternative, according to acquired efficiency with the employment of TiO2 (titanium dioxide) and Mn-doped TiO2 thin films. In the scope of this work, TiO2 (titanium dioxide) and Mn:TiO2 hybrid organic thin films are proposed as charge transporter layer in polymer solar cells. Poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT: PCBM) is used as active layer. When the Mn-doped TiO2 solar cells were compared with pure TiO2 cells, Mn-doped samples revealed a noteworthy efficiency enhancement with respect to undoped-TiO2-based cells. The highest conversion efficiency was obtained to be 2.44% at the ratio of 3.5% (wt/wt) Mn doping

High Mobility and Low Operation Voltage Organic Field Effect Transistors by Using Polymer-Gel Dielectric and Molecular Doping

In this work, we present a method to increase the performance in solution processed organic field effect transistors (OFET) by using gel as dielectric and molecular doping to the active organic semiconductor. In order to compare the performance improvement, Poly (methylmethacrylate) (PMMA) and Poly (3-hexylthiophene-2,5- diyl) P3HT material system were used as a reference. Propylene carbonate (PC) is introduced into PMMA to form the gel for using as gate dielectric. The mobility increases from 5.72×10−3 to 0.26 cm2 V s–1 and operation voltage decreases from −60 to −0.8 with gel dielectric. Then, the molecular dopant 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4-TCNQ) is introduced into P3HT via co-solution. The mobility increases up to 1.1 cm2 V s–1 and the threshold voltage downs to−0.09 V with doping. The increase in performance is discussed in terms of better charge inducing by high dielectric properties of gel and trap filling due to the increased carrier density in active semiconductor by molecular doping