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Publication Metadata only A metal nitride carbodiimide with a stuffed skutterudite-type structure: synthesis, crystal structure and ir spectra of (BA6N 5/6)2[NBN4][CN2]6(Walter de Gruyter, 2007) Reckeweg, Olaf; Disalvo, Francis J.; Department of Chemistry; Somer, Mehmet Suat; Faculty Member; Department of Chemistry; College of Sciences; 178882Coppery-red, transparent single crystals of (Ba6N 5/6)2[NbN4][CN2]6 [NbN4] [CN2]6 (Im3̄, no. 204, a = 1125.83(3) pm, Z = 2) are obtained by the reaction of Ba2N and ZnCN2 with the container walls of the arc-welded Nb ampoules at 1100 K. The title compound assumes a stuffed skutterudite-type structure in which edge-sharing (Ba6N5/6) octahedra form large voids which are occupied by either [NbN4] tetrahedra or by [N=C=N]2- units with symmetric C=N bond lengths of d = 121.8(6) pm but a bond angle deviating significantly from linearity (∠(N-C-N) = 175.3(9)°). The IR spectra corroborate this crystallographic result by the fact that all fundamental vibrations are visible in the IR spectrum [v1 = 1262 (symmetric stretching mode); v2 = 1957/2009 (antisymmetric stretching mode); v3 = 611/633/653 cm-1 (bending modes)], which is symmetry forbidden for [N=C=N]2- units having D∞h symmetry but expected for the C2v symmetry found in the title compound.Publication Metadata only Azidoaurates of the alkali metals(Wiley, 2006) Hoehn, Peter; Armbruester, Marc; Baranov, Alexey; Wagner, Frank R.; Kniep, Ruediger; N/A; Department of Chemistry; Afyon, Semih; Somer, Mehmet Suat; Undergraduate Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178882Synthesis, crystal structure as well as IR- and Raman-spectroscopic properties of the new ternary azidoaurates(III) A[Au(N-3)(4)] (A = K Rb, Cs) are reported. The translucent orangered compounds were prepared by reaction of the respective binary azides with HAuCl4 in aqueous solutions at room temperature. The crystal structures determined by single crystal X-ray diffraction methods are monoclinic (C2/c (No. 15), K/Rb/Cs[Au(N-3)(4)]: a = 1049.30(9) pm / 1033.93(10) pm / 1011.9(8) pm, b = 1047.52(8) pm / 1064.20(11) pm / 1093.8(8) pm, c = 776.97(7) pm / 809.79(8) pm / 858.4(6) pm, beta = 91.220(5)degrees / 90.322(5)degrees / 92.72(5)degrees) and provide the first examples for azidoaurates with mono-atomic cations. The unusual reduction of the lattice parameter a with increasing cation size in the isotypic series is discussed in detail. IR and Raman-spectroscopic measurements show strongly covalent gold-nitrogen contacts, a bonding situation which is further supported by quantum chemical calculations and ELF-analyses.Publication Open Access Blue TiO2 nanotube arrays as semimetallic materials with enhanced photoelectrochemical activity towards water splitting(TÜBİTAK, 2020) Department of Chemistry; Peighambardoust, Naeimeh Sadat; Aydemir, Umut; Researcher; Faculty Member; Department of Chemistry; Koç University AKKİM Boron-Based Materials _ High-technology Chemicals Research _ Application Center (KABAM) / Koç Üniversitesi AKKİM Bor Tabanlı Malzemeler ve İleri Teknoloji Kimyasallar Uygulama ve Araştırma Merkezi (KABAM); College of Sciences; N/A; 58403In the past years there has been a great interest in self-doped TiO2 nanotubes (blue TiO2 nanotubes) compared to undoped ones owing to their high carrier density and conductivity. In this study, blue TiO2 nanotubes are investigated as photoanode materials for photoelectrochemical water splitting. Blue TiO2 nanotubes were fabricated with enhanced photoresponse behavior through electrochemical cathodic polarization on undoped and annealed TiO2 nanotubes. The annealing temperature of undoped TiO2 nanotubes was tuned before cathodic polarization, revealing that annealing at 500 degrees C improved the photoresponse of the nanotubes significantly. Further optimization of the blue TiO2 nanotubes was achieved by adjusting the cathodic polarization parameters. Blue TiO2 nanotubes obtained at the potential of -1.4 V (vs. SCE) with a duration of 10 min exhibited twice more photocurrent response (0.39 mA cm(-2)) compared to the undoped TiO(2 )nanotube arrays (0.19 mA cm(-2)). Oxygen vacancies formed through the cathodic polarization decreased charge recombination and enhanced charge transfer rate; therefore, a high photoelectrochemical activity under visible light irradiation could be achieved.Publication Metadata only Bosonic helium clusters doped by alkali metal cations: interaction forces and analysis of their most stable structures(Springer, 2007) Marinetti, Fabio; Coccia, Emanuele; Bodo, Enrico; Gianturco, Franco A.; Yurtsever, Mine; Yıldırım, Erol; Department of Chemistry; Yurtsever, İsmail Ersin; Faculty Member; Department of Chemistry; College of Sciences; 7129Ab initio potentials are computed for alkali metal cationic partners interacting with He-4 and an overall many-body potential is constructed for each of the ionic dopants in helium clusters. The structures are then obtained via a genetic algorithm approach and results compared with Basin-Hopping Monte Carlo simulations. The classical arrangements are analyzed and quantum effects discussed in comparison with what has been found with Diffusion Monte Carlo calculations. Further corrections to the classical picture by including three-body forces and radial delocalization of the helium adatoms are also considered and their effects analyzed.Publication Metadata only Ca-2[BN2]H: The first nitridoborate hydride - synthesis, crystal structure, and vibrational spectra(Wiley, 2004) Reckeweg, Olaf; Protsc,Yurii; Carrillo-Cabrera, Wilder; Department of Chemistry; Department of Chemistry; Somer, Mehmet Suat; Yaren, Özlem; Faculty Member; Undergraduate Student; Department of Chemistry; College of Sciences; College of Sciences; 178882; N/ACa-2[BN2]H was synthesized from a mixture of the binary components Ca3N2, CaH2 and BN (molar ratio 1 : 1 : 2) in a sealed steel ampoule encapsulated in an evacuated silica tube at 1273 K. Ca-2[BN2]H crystallizes in the orthorhombic space group Pnma (no. 62) with a = 9.2015(8) Angstrom, b = 3.6676(2) Angstrom and c = 9.9874(12) Angstrom (Z = 4; Pearson symbol oP24). The crystal structure is a filled variant of the Co2P type and can be formulated as Co2P(square(t))(3)(square(py))(3) drop Ca-2[N-B-N]H(square(t))(2)(square(py))(3) (square(t) and square(py) = tetrahedral and square-pyramidal hole, respectively). The d(B-N) bond lengths and bond angle for the linear [N-B-N](3-) anion are: d(B-N1) = 1.324(3) Angstrom, d(B-N2) = 1.350(2) Angstrom and angleN-B-N = 177.2(2)degrees. The vibrational spectra of Ca-2[BN2]H confirm the presence of [N-B-N](3-) groups deviating only slightly from the ideal D-infinityh symmetry. The vibrational frequencies and the f(B-N) force constants are discussed and compared with those of the isotypic compound Ca-2[BN2]F.Publication Metadata only Competitive hydrogen bonding in aspirin-aspirin and aspirin-leucine interactions(Scientific Technical Research Council Turkey-Tubitak, 2012) Department of Chemistry; Department of Chemical and Biological Engineering; Department of Chemistry; Yurtsever, Zeynep; Erman, Burak; Yurtsever, İsmail Ersin; Undergraduate Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Department of Chemistry; College of Sciences; College of Engineering; College of Sciences; N/A; 179997; 7129Aspirin-aspirin and aspirin-leucine interactions are studied by the density functional theory (DFT) and high level ab initio calculations with second order Moller-Plesset perturbation theory (MP2). The rotational isomers of aspirin are identified by their relative stability both in gaseous phase and in water using the polarizable continuum method (PCM). Local minima of aspirin monomers in water are found to be all highly populated compared to the gas phase behavior. Homodimers of aspirin form hydrogen bonds with bond energies of 10 kcal/mol. Weak hydrogen bonds utilizing phenyl and methyl groups are also found. The interaction between aspirin and leucine is stronger with relatively short bond lengths compared to homodimeric aspirin interactions. The potential energy surface has several minima with comparable stability. This study shows the significance of diverse bonding schemes, which are important for understanding complete interaction mechanisms of aspirin.Publication Metadata only Crystal structure of 3R(S)-1 ' S(R)-2,2-dimethoxycarbonyl-3-(2 ',6 ',6 '-trimethyl-2 '-cyclohexen-1 '-yl)-2,3-dihydrofuran, C18H26O5(Walter De Gruyter Gmbh, 2002) Daut-Özdemir, Ayşe; Anaç, Olcay; Borrmann, Horst; Department of Chemistry; Somer, Mehmet Suat; Faculty Member; Department of Chemistry; College of Sciences; 178882N/APublication Metadata only Crystal structure of bis[mu(2)-(3-benzimidazol-2-yl)-2-ethanethiolato-N,S,S)-chloro-palladium(II)], [(C6H4N2HCCH2CH2S)PdCl](2) center dot C2H5OH(Oldenbourg Verlag, 2005) Agh-Atabay, Naz Mohammed; Borrmann, Horst; Department of Chemistry; Department of Chemistry; Somer, Mehmet Suat; Haciu, Durata; Faculty Member; Teaching Faculty; Department of Chemistry; College of Sciences; College of Sciences; 178882; N/AC20H24Cl2N4OPd2S2, triclinic, P (1) over bar (no. 2), a = 8.796(1) angstrom, b = 9.844(1) angstrom, c = 14.718(2) angstrom, alpha = 94.330(6)degrees, beta = 98.546(6)degrees, gamma = 99.258(7)degrees, V = 1237.3 angstrom(3), Z = 2, R-gt(F) = 0.068, wR(ref)(F-2) = 0.142, T = 295 K.Publication Metadata only Crystal structure of bis[μ2-(3-benzimidazol-2-yl)-2- ethanethiolato-N,S,S-chloro-palladium(II)], [(C6H4N 2HCCH2CH2S)PdCl]2 · C 2H5OH(Walter de Gruyter GmbH, 2005) Agh-Atabay, N.M.; Borrmann, H.; Department of Chemistry; Department of Chemistry; Somer, Mehmet Suat; Haciu, Durata; Faculty Member; Teaching Faculty; Department of Chemistry; College of Sciences; College of Sciences; 178882; N/AC20H24Cl2N4OPd 2S2, triclinic, P1̄ (no. 2), a = 8.796(1) Å, b = 9.844(1) Ä, c = 14.718(2) Ä, α = 94.330(6)°, β = 98.546(6)°, γ = 99.258(7)°, V = 1237.3 Å3, Z = 2, Rgt(F) = 0.068, wRref(F2) = 0.142, T = 295 K.Publication Metadata only Crystal structure of bis[µ2-(3-benzimidazol-2-yl)-2-ethanethiolato-N,S,S)- chloro-palladium(II)], [(C6H4N2HCCH2CH2S)PdCl]2 C2H5OH(Walter de Gruyter GmbH, 2005) Agh-Atabay, N.M.; Borrmann, H.; Department of Chemistry; Department of Chemistry; Somer, Mehmet Suat; Haciu, Durata; Faculty Member; Teaching Faculty; Department of Chemistry; College of Sciences; College of Sciences; 178882; N/AC20H24Cl2N4OPd2S2, triclinic, P1 (no. 2), a = 8,796(1) Å, b = 9.844(1) Å, c = 14.718(2) A, α = 94.330(6)°, β = 98.546(6)°,γ = 99.258(7)°, V= 1237.3 Å3, Z= 2, Rgt(F) = 0.068, wRref(F2)= 0.142, T= 295 K.