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Publication Metadata only 3D coffee stains(Royal Soc Chemistry, 2017) N/A; N/A; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Department of Molecular Biology and Genetics; Department of Chemistry; Department of Chemistry; Department of Electrical and Electronics Engineering; Doğru-Yüksel, Itır Bakış; Söz, Çağla Koşak; Press, Daniel Aaron; Melikov, Rustamzhon; Begar, Efe; Çonkar, Deniz; Karalar, Elif Nur Fırat; Yılgör, Emel; Yılgör, İskender; Nizamoğlu, Sedat; PhD Student; PhD Student; Researcher; PhD Student; PhD Student; PhD Student; PhD Student; Faculty Member; Researcher; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Chemistry; Department of Electrical and Electronics Engineering; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); N/A; N/A; N/A; N/A; N/A; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 206349; N/A; 24181; 130295When a liquid droplet (e.g., coffee, wine, etc.) is splattered on a surface, the droplet dries in a ring-shaped stain. This widely observed pattern in everyday life occurs due to the phenomenon known as a coffee stain (or coffee ring) effect. While the droplet dries, the capillary flow moves and deposits the particles toward the pinned edges, which shows a 2D ring-like structure. Here we demonstrate the transition from a 2D to a 3D coffee stain that has a well-defined and hollow sphere-like structure, when the substrate surface is switched from hydrophilic to superhydrophobic. The 3D stain formation starts with the evaporation of the pinned aqueous colloidal droplet placed on a superhydrophobic surface that facilitates the particle flow towards the liquid-air interface. This leads to spherical skin formation and a cavity in the droplet. Afterwards the water loss in the cavity due to pervaporation leads to bubble nucleation and growth, until complete evaporation of the solvent. In addition to the superhydrophobicity of the surface, the concentration of the solution also has a significant effect on 3D coffee stain formation. Advantageously, 3D coffee stain formation in a pendant droplet configuration enables the construction of all-protein lasers by integrating silk fibroin with fluorescent proteins. No tools, components and/or human intervention are needed after the construction process is initiated; therefore, 3D coffee-stains hold promise for building self-assembled and functional 3D constructs and devices from colloidal solutions.Publication Metadata only A coarse graining approach in molecular simulations: fuzzy potentials(Istanbul Technical University, 2003) Department of Chemistry; Department of Chemistry; Yurtsever, İsmail Ersin; Eşsiz, Şebnem; Faculty Member; Undergraduated Student; Department of Chemistry; College of Sciences; College of Sciences; 7129; 191615A new representation for interaction potential functions is presented. Unlike the orthodox approaches, the potential function is not a fixed function in terms of internuclear coordinates but a probabilistic one which contains information over a wide range of angular degrees of freedom. It is shown that such approaches can provide practical solutions for bulk systems of high density.Publication Metadata only A facile synthesis of mesoporous graphitic carbon nitride supported palladium nanoparticles as highly effective and reusable catalysts for Stille coupling reactions under mild conditions(Royal Soc Chemistry, 2020) N/A; Department of Chemistry; N/A; Department of Chemistry; Department of Chemistry; Kalay, Erbay; Çetin, Sultan; Kölemen, Safacan; Metin, Önder; Researcher; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; 59456; N/A; 272051; 46962The development of a Stille coupling protocol that is operable under moderate conditions without using a base is highly required for the synthetic organic chemistry community, which requires an efficient nanocatalyst. In this respect, addressed herein is a facile one-pot synthesis of mesoporous graphitic carbon nitride (mpg-CN) supported Pd NPs, denoted as mpg-CN/Pd hereafter, and investigation of their catalytic activity in Stille cross-coupling reactions for the first time. It has been demonstrated that mpg-CN nanosheets can serve as not only a support material but also a stabilizer for the generation of 4.5 nm Pd NPs. The ecofriendly generated heterogeneous nanocatalyst was characterized by TEM, XRD, XPS, BET surface area and ICP-MS analysis. The mpg-CN/Pd nanocatalysts showed high activity in the Stille coupling reaction of a variety of electron-deficient and electron-rich aryl iodides/bromides and two different organostannanes with a wide substrate scope to afford the corresponding biaryls without using any bases and additional ligands under relatively mild conditions. The catalyst can be easily recovered from the reaction medium by centrifugation. It can be reused at least 5 times without any loss of activity.Publication Metadata only A facile synthesis of monodisperse cobalt–ruthenium alloy nanoparticles as catalysts for the dehydrogenation of morpholine borane and the hydrogenation of various organic compounds(Royal Soc Chemistry, 2022) Can, Hasan; Can, Sumeyra; Ebiri, Rustem; Department of Chemistry; Metin, Önder; Faculty Member; Department of Chemistry; College of Sciences; 46962Herein we report a novel wet-chemical protocol for the composition-controlled synthesis of monodisperse cobalt-ruthenium (CoRu) alloy NPs and their catalysis in the hydrolytic dehydrogenation of morpholine borane (MB) for chemical hydrogen storage and the hydrogenation of various organic compounds using MB as a hydrogen source. Monodisperse CoRu NPs with an average particle size of 1.7 +/- 0.6 nm at three different alloy compositions were prepared by the presented novel protocol that comprises the reduction of in situ formed ruthenium(iii) oleate complex with dicobalt octacarbonyl (Co-2(CO)(8)) in the presence of oleylamine (OAm). Next, as-synthesized CoRu alloy NPs were supported on carbon black (VC) and reduced graphene oxide (rGO) to study their catalysis in the dehydrogenation of MB and the transfer hydrogenation of various organic compouns bearing unsaturated functional groups (nitro, nitrile and carbonyl) using MB as a hydrogen source, respectively. VC-CoRu nanocatalysts exhibited a higher catalytic activity in hydrogen generation from the hydrolysis of MB with an initial turnover frequency (TOF) of 95 mol H-2*(mol (Co + Ru) min)(-1) while rGO-CoRu nanocatalysts showed better catalytic performance in the transfer hydrogenation reactions. All tested unsatured organic compounds (30 examples in total) are converted into corresponding hydrogenated products with the yields reaching up to 99% under mild conditions.Publication Metadata only A leucine aminopeptidase activatable photosensitizer for cancer cell selective photodynamic therapy action(Elsevier Sci Ltd, 2021) N/A; N/A; N/A; Department of Chemistry; N/A; Department of Physics; Department of Chemistry; Department of Chemistry; Arslan, Büşra; Bilici, Kübra; Demirci, Gözde; Almammadov, Toghrul; Khan, Minahil; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; Kölemen, Safacan; Master Student; PhD Student; Master Student; Researcher; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezi (KUBAM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; N/A; N/A; N/A; 23851; 178902; 272051Activity based photosensitizers (PS) continue to attract great attention as they enable selective photodynamic therapy action on cancer cells while sparing normal cells even under light irradiation. Sensitivity to specific enzymes that are differentially overexpressed in cancer cells is crucial in the design of activatable PSs. In this direction, we report here, for the first time, a leucine aminopeptidase (LAP) activatable PDT agent (HCL), which is a red-shifted, water soluble and photostable brominated hemicyanine derivative. HCL was activated by endogenous LAP enzyme selectively in A549 (lung) and HCT116 (colon) cancer cells containing high LAP levels and induced effective photocytotoxicity with negligible dark toxicity. Furthermore, the fluorescence of the parent bromo-hemicyanine core was restored upon LAP-based activation in cancer cells. On the other side, no remarkable phototoxicity or fluorescence turn-on was detected in healthy L929 cells. Thus, HCL serves as an effective and tumour associated LAP-sensitive phototheranostic agent. We believe different cancer-associated analytes can be utilized in combination with near-IR absorbing scaffolds in the scope of activatable PDT designs to enrich the tumour-selective PS arsenal.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 A metal nitride carbodiimide with a stuffed skutterudite-type structure: synthesis, crystal structure and IR spectra of (Ba6N5/6) 2[NbN4][CN2] 6(Walter De Gruyter Gmbh, 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 (Ba6N5/6)(2)[NbN4][CN2](6) (Im (3) over bar, 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 (measured angle(N-C-N) = 175.3(9)degrees). The IR spectra corroborate this crystallographic result by the fact that all fundamental vibrations are visible in the IR spectrum [v(1) = 1262 (symmetric stretching mode); v(2) = 1957/2009 (antisymmetric stretching mode); v(3) = 611/633/653 cm(-1) (bending modes)], which is symmetry forbidden for [N=C=N](2-) units having D-infinity h symmetry but expected for the C-2v symmetry found in the title compound.Publication Open Access A near-infrared benzothiazole-based chemodosimeter for rapid and selective detection of hydrogen sulfide(Turkish Chemical Society / Türkiye Kimya Derneği, 2021) Department of Chemistry; Kölemen, Safacan; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezi (KUBAM); College of Sciences; 272051Hydrogen sulfide (H2S) is a biologically relevant gaseous molecule, which involves in a wide variety of physiological and pathological processes. Thus, detection of H2S is highly valuable in order to clarify its complex roles. In this study, a new benzothiazole-based donor-acceptor type H 2S selective chemodosimeter (HP-1) was synthesized and its H2S detection capabilities were investigated in aqueous solutions. HP-1 exhibited a red-shifted absorption signal at 530 nm and a near-infrared (NIR) fluorescence peak at 680 nm as a result of enhanced intramolecular charge transfer (ICT) in the presence of H2S, which enabled a selective and very rapid ratiometric fluorescent detection. HP-1 was also showed to be highly sensitive toward H2S with a very low limit of detection value.Publication Open Access A new class of porous materials for efficient CO2 separation: ionic liquid/graphene aerogel composites(Elsevier, 2021) Department of Chemical and Biological Engineering; N/A; Department of Chemistry; Zeeshan, Muhammad; Yalçın, Kaan; Keskin, Seda; Uzun, Alper; Öztuna, Feriha Eylül Saraç; Ünal, Uğur; PhD Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Engineering; College of Sciences; N/A; N/A; 40548; 59917; N/A; 42079Here, we report a new post-synthesis modification strategy for functionalizing reduced graphene aerogels (rGAs) towards an exceptional CO2 separation performance. 1-N-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) was impregnated on a rGA, prepared by reducing GA at 700 degrees C, at various ionic liquid (IL) loadings of 5, 10, 30, and 50 wt%. The resulting composites were characterized in deep detail by X-ray photoelectron spectroscopy, X-ray diffraction, N-2 physical adsorption measurements, scanning electron microscopy, Fourier transform infrared and Raman spectroscopies, and thermogravimetric analysis. Results indicated the presence of interactions between the rGA surface and the anion of the IL, potentially improving the CO2 affinity. Volumetric gas adsorption measurements using these materials showed that the deposition of [BMIM][PF6] on rGA surface at an IL loading of 50 wt% boosts the CO2/CH4 selectivity by more than 20-times, exceeding an absolute value of 120, a remarkably higher CO2/CH4 selectivity compared to that of other functionalized materials under similar operating conditions. Tunability of both the IL structure and the surface characteristics of rGA offer a tremendous degree of flexibility for the rational design of these IL/rGA composites towards high performance in gas separation applications.Publication Metadata only A new generation of highly branched polymers: hyperbranched, segmented poly(urethane urea) elastomers(American Chemical Society (ACS), 2004) Ünal, S.; Sheth, J.P.; Wilkes, G.L.; Long, T.E.; Department of Chemistry; Department of Chemistry; Yılgör, Emel; Yılgör, İskender; Researcher; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; 40527; 24181A simple oligomeric A 2 + B 2 approach was described for the preparation of segmented, hyperbranched polyureas and poly(urethane urea). The approach utilized an isocyanate end-capped polyether as an oligomeric A 2 monomer and B 3 triamine monomer. The approach can be extended to a large number of telechelic oligomers including poly(dimethylsiloxane) (PDMS) or poly (ethylene glycol) and trifunctional polymer (B 3) to prepare polymeric materials. The similarity in soft segment glass transition behavior and strain hardening character of the hyperbranched systems suggested considerable promise for future applications.