33 research outputs found

    Religion, Law, War

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    This course will expose participants to fundamental understanding of religion, law and war focusing on the nexus of the three. It will do so in a highly participatory manner. The course will focus on the three terms separately and in relation to each other. As both CORE and Diplomacy course, students from different background will be encouraged to learn from one another and be aware of their own learning. The course will encourage a critical subjective response from participants. It will invite an analysis of three original documents: the Vatican II document ‘Nostra Aetate’; the United Nations Declaration of Human Rights; and the UNESCO document on peace as well as actual cases of interest

    Pyrene bisiminopyridine ligand and its zinc complex

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    The synthesis of a pyrene bisiminopyridine ligand L was successfully accomplished by condensation between 1-aminopyrene and 2,6-pyridinecarboxaldehyde. The complexation of L with zinc triflate afforded a neutral metal complex formulated as [Zn(H2O)LCF3SO3)2].2Et2O. In the complex, the ligand is coordinated to zinc(II) through its three nitrogen atoms which form a distorted octahedral environment together with three oxygen atoms, two from the triflate anions and one from aqua ligand. Both compounds have been characterized using NMR, elemental analysis, mass spectrometry, electronic absorption (UV-Vis) and infrared. Luminescence properties of these compounds show an emission maxima at 412 nm, indicating a pyrene monomer emission

    Coordination entities of a Pyrene-based Iminopyridine ligand: Structural and photophysical properties

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    A pyrene-based iminopyridine ligand L has been prepared and displays the absorption and emission properties expected for pyrene-based derivatives in solution. Ligand L, as well as two neutral and one monocationic coordination entities, respectively formulated as [ZnLCl2] 1, [ReLCl(CO)3] 3 and [CuL2](BF4) 2, have been crystallized and analyzed by single crystal X-ray diffraction analysis. The corresponding crystal structures indicate the formation of supramolecular architectures generated by offset π···π stacking between pyrene fragments and strong C-H···π interactions in coordination entity 1. For the cationic coordination entity 2, the crystal packing reveals the presence of C-H···F and C-H···π interactions and numerous C-H···π contacts interconnecting the molecules into a 3D network. As for coordination entity 3, hydrogen bonding and π···π stacking link the molecules in a three dimensional manner. Zinc (II) and copper (I) coordination entities have also been studied through isothermal titration calorimetry, which indicate a strong binding and a different stoichiometry for both coordination entities. Photophysical studies of the ligand and corresponding coordination entities show a monomer type pyrene emission and a higher fluorescence quantum yield for the zinc coordination entity 1 as compared with copper 2 and rhenium 3 coordination entities

    Synthesis and spectroscopic properties of a novel perylenediimide derivative

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    A novel symmetric 3,4,9,10-perylenetetracarboxylic acid derivative (PDI1) dye based on thiophene donor group was synthesized and characterized by FT-IR and 1H NMR. Cyclic Voltammetry analysis is performed to determine the energy levels of the perylene derivative. Optical characteristics were determined by visible absorption and fluorescence emission spectra. Spectral behavior and fluorescence quantum yield of PDI1 have been measured in different solvents. The dye exhibits high fluorescence quantum yield ( Φf: 0.94-0.99). But the quantum yield PDI1 is very low in the n-butanol solution ( Φf: 0.12). The photophysical properties have important implications for use in a variety of electroactive and photovoltaic applications. A photovoltaic device was fabricated with PDI1 as transporting material. The conversion efficiency for DSSC sensitized by PDI1 is 0.0065%. PDI1 exhibits electrochromic behavior by switching between neutral (red) and oxidized (blue) states. Electron transfer capacity of PDI to the TiO2 was investigated by incorporation of dye as sensitizer in dye sensitized solar cell (DSSC). Soluble dye molecules are very important to prepare dye sensitized solar cell. Solubility was increased with thiophene group

    DYES AND PIGMENTS

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    New kind of azo chromophores containing thiophene moiety and salicyaldimine-based ligand as side chains have been synthesized by a sequential process for optical sensing of Cu2+ metal ions in organic solution. Compounds have been characterized by IR and UV-vis spectrophotometer, H-1 NMR, C-13 NMR, MS, TGA and CV instruments. Spectral characteristics of the synthesized compounds have been investigated in five organic solvents of different polarity. Polarizibility effects of the solvents on the spectral characteristics and the dipole moments in the excited state are estimated. The fluorescence quantum yields of the synthesized compounds have been calculated to be in the range of 0.0035-0.0095 in solvents of different polarity. The fluorescence emission quenching experiments between the synthesized compounds and electron donor (pyrene, anthracene), electron acceptor (Co2+) compounds give the bimolecular quenching rate constants of 10(11) and 10(14) M-1 s(-1), respectively. The free energies of photo-electron transfer process (Delta G(ET)) between the azo dyes and the quenchers have been found to be about -19 kcal/mol. Cyclic voltammetry studies indicate that synthesized azo ligands undergo two- or three-reversible reduction potentials (versus ferrocene) and give LUMO energy value of -3.07 eV which is lower than that of TiO2 conduction band and has a band gap value of similar to 2.5 eV. These results may point that synthesized azo, dyes could be used as hole conducting materials in solid DSSC (Dye Sensitized Solar Cell) devices. Thermal decomposition behavior of the azo dyes gives more information about the structure of the studied materials. The photoisomerization behavior of the synthesized compounds has been investigated in ethyl acetate under Xe lamp irradiation in the fluorescence spectrophotometer for 1 h. Photoisomerization rate constants of cis-trans orientation (k(c-t)) have been found to be about 10(-5) s(-1). The complexation process of synthesized thienylidene azo dyes gives subtle changes in their absorption spectra. (C) 2006 Elsevier Ltd. All rights reserved

    SOLAR ENERGY

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    A new water-soluble perylene diimide derivative, N,N'-bis(12-sulfoaminododecyl)-3,4,9,10-perylenetetracarboxdiimide (SULFAPER), has been synthesized and characterized by visible, fluorescence, IR, H-1 and C-13 NMR, mass, CV and time resolved measurements. Its photophysical properties in aqueous and organic solutions have been described. The singlet energy levels of the synthesized compound have been found to be 57.8 kcal/mol and 59.2 kcal/mol in aqueous and methanol solution, respectively. The LUMO energy level of SULFAPER has been determined by solid state cyclic voltammetry, and found to be -3.60 eV. SULFAPER undergoes two electron reduction process (-0.64 V and -0.42 V) versus ferrocene. SULFAPER has an energy band gap of 2.56 eV. The absorption maximum of the synthesized compound gives bathochromic shift of 12 nut in water with respect to its visible spectrum in methanol solution. The fluorescence quantum yields of the compound are low both in water and methanol solution because of the aggregation effect. Time-resolved fluorescence measurements have showed that the fluorescence decay times of the SULFAPER are tau(1) = 4.1 ns and tau(2) = 0.8 ns in water, and tau(1) = 4.0 ns and tau(2) = 2.5 ns in methanol solutions. The aqueous solution of SULFAPER is stable under UV-VIS irradiation, but a slight loss of fluorescence emission (25%) has been detected at a rate of k(p) = 6.3 x 10(-5) s(-1) in methanol solution, which might be the result of either the quenching of fluorescence emission by reactive oxygen species, or by enhanced aggregation effect. SULFAPER-sensitized photooxidations of (E)-cinnamic acid and methyl acrylate have been found to give selective photoproduct formations under concentrated sun light in organic phase. (E)-cinnamic acid has been seen to favor photochemical E-Z isomerization and methyl acrylate has been seen to favor the formation of methyl 2-oxopropanoate. The quantum yield of (E)-cinnamic acid (Phi(CA)) under concentrated solar irradiation process has been calculated to be about 0.015, by the employment of an actinometry method developed by Erten and Icli. (c) 2005 Elsevier Ltd. All rights reserved

    OPTICAL MATERIALS

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    Three electron-deficient small molecules based on 2,1,3-benzothiadiazole (BTD) units namely, 4,7-bis (3-methoxyphenyl)-2,1,3-benzothiadiazole (BT1), (3-{7-[3-(dimethylamino)phenyl]-2,1,3-benzothiadiazole-4-yl}phenyl)dimethylamine (BT2) and 3,3'-(2,1,3-benzothiadiazole-4,7-dyl)dianiline (BT3) were synthesized and their photophysical properties were investigated systematically to understand their potential usage in ternary organic solar cells (OSCs) as additive material to enhance the cell efficiency. All these molecules show broad absorption bands in 350-750 nm on glass substrate and their optical band gaps were calculated to be around 2.50-2.80 eV. BTD fluorescence dynamics were measured in polymer:BT1:fullerene blends with varying emission wavelengths of active layer. Fluorescence emission and time resolved measurements indicated photoinduced energy shift from BT1 dye to fullerene and also from polymer to BT1 dye upon excitation of the active layer. (C) 2014 Elsevier B.V. All rights reserved

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

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    A series of new unsymmetrical perylene diimides have been synthesized to investigate their binding selectivities to G-quadruplex DNA structure, a unique four-stranded DNA motif, which is significant to the regulation of telomerase activity. The structures of the perylene diimides have been characterized by IR spectrophotometer, H-1 NMR, C-13 NMR, MS, TGA and time-resolved instruments. Spectrochemical behaviors have been investigated by visible absorption and fluorescence emission spectra. The spectral characterization of the compounds has been investigated in five common organic solvents of different polarity and in water (in 170 mM phosphate buffer at pH 6). Marked red shifts of absorbance and fluorescence emission bands of the compounds in aqueous solution are compared with the other organic solutions. The fluorescence quantum yields are determined low in more polar solvents and also calculated to be about less than about 0.05 in aqueous solution because of the aggregation effects. Photodegradation rate constants (k(p)) of the synthesized compounds have been compared under xenon lamp irradiation in acetonitrile solution. Binding abilities of the synthesized perylene diimides to different form of DNA strands have been investigated by visible absorption and fluorescence spectroscopy in the phosphate buffer solutions. Also, pH-dependent aggregation and G-quadruplex DNA binding selectivity of these ligands have been compared. Among these ligands, N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)-perylene-3,4,9,10-tetracarboxylic diimide (PYPER) has been found to be the most selective interactive ligand for G-quadruplex formed in the G4'-DNA structure. PYPER has shown a significant selectivity to G4'-DNA which is comprised of d(TTAGGG) repeats, known as human telomeres, in the phosphate buffer at pH 6. The absorption maximum of the PYPER/G4'-DNA complex has given bathochromic shift of 7 nm with respect to the absorption maximum of DNA-free solution of PYPER in phosphate buffer at pH 6. Fluorescence quenching experiments between PYPER and G4'-DNA show that PYPER demonstrates about a 9.3-fold selectivity for binding to G4'-DNA versus ds-DNA base pairs with the bimolecular rate constant of 0.95 x 10(12) M-1 s(-1). (c) 2006 Elsevier B.V. All rights reserved

    SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

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    Five isoindigo-based donor-acceptor-donor (D-A-D) type small molecules have been synthesized in order to investigate their intramolecular charge transfer characteristics. UV-vis absorption of these dyes exhibits a wide absorption band ranging from 300 to 650 nm with two distinct bands, giving the narrow bandgaps between 1.72 and 1.85 eV. Taking into account their HOMO-LUMO energy levels and bandgaps, isoindigo dyes have been used in the active layer of organic solar cell (OSC) devices. When these small molecule semiconductors were used as acceptors with the donor poly(3-hexylthiophene-2,5-diyl (P3HT) polymer in the inverted OSC devices, the highest power conversion efficiency (PCE) was obtained as 0.10% for pyrene-substituted isoindigo derivative. (C) 2018 Elsevier B.V. All rights reserved
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