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Publication Metadata only Enhanced water stability and high CO2 storage capacity of a Lewis basic sites-containing zirconium metal-organic framework(2021) Demir, Selçuk; Bilgin, Nuray; Çepni, Hamide Merve; Furukawa, Hiroyasu; Yılmaz, Fatih; N/A; Department of Chemical and Biological Engineering; Altıntaş, Çiğdem; Keskin, Seda; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548Metal–organic frameworks (MOFs) are an emerging class of materials employed for custom-designed purposes by judicious selection of linkers and metal ions. Among the MOFs composed of carboxylate linkers, Zr-based MOFs have attracted great attention due to their high thermal and chemical stabilities, which are important for practical applications, including capturing CO2 from a point source. UiO-67(bipy) containing 2,2′-bipyridine-5,5′-dicarboxylate is particularly useful among the Zr-MOF family due to the Lewis basic sites of the linker; however, the hydrolytic stability of UiO-67(bipy) does not seem to be as high as those of UiO-66 and UiO-67. To improve the hydrolytic stability without sacrificing the adsorption enthalpy of CO2 for selective CO2 capture, in this study, we added hydrophobic methyl groups to the backbone of the bipyridine linker. The synthesized 6,6′-dimethyl-2,2′-bipyridine-5,5′-dicarboxylic acid (H2Me2bipy) was used to prepare a Zr-based MOF [MOF-553, Zr6O4(OH)4(Me2Bipy)6]. In addition, the water stability and CO2 adsorption capacity of MOF-553 were compared to those of UiO-67(bipy). We revealed that MOF-553 is more robust and has a higher CO2 adsorption capacity than UiO-67(bipy), indicating that the methylation of the linker improves the water stability of the framework, which is advantageous for point-source CO2 capture.Publication Metadata only Isotropic zero thermal expansion and local vibrational dynamics in (SC,FE)F-3(American Chemical Society (ACS), 2017) Qin, Feiyu; Chen, Jun; Sanson, Andrea; Wang, Lu; Pan, Zhao; Xu, Jiale; Sun, Chengjun; Ren, Yang; Deng, Jinxia; Yu, Ranbo; Hu, Lei; Snyder, G. Jeffrey; Xing, Xianran; Department of Chemistry; Aydemir, Umut; Faculty Member; Department of Chemistry; College of Sciences; 58403Scandium fluoride (ScF3) exhibits a pronounced negative thermal expansion (NTE), which can be suppressed and ultimately transformed into an isotropic zero thermal expansion (ZTE) by partially substituting Sc with Fe in (Sc0.8Fe0.2)F-3 (Fe20). The latter displays a rather small coefficient of thermal expansion of -0.17 X 10(-6)/K from 300 to 700 K. Synchrotron X-ray and neutron pair distribution functions confirm that the Sc/ Fe-F bond has positive thermal expansion (PTE). Local vibrational dynamics based on extended X-ray absorption fine structure indicates a decreased anisotropy of relative vibration in the Sc/Fe-F bond. Combined analysis proposes a delicate balance between the counteracting effects of the chemical bond PTE and NTE from transverse vibration. The present study extends the scope of isotropic ZTE compounds and, more significantly, provides a complete local vibrational dynamics to shed light on the ZTE mechanism in chemically tailored NTE compounds.Publication Metadata only New ternary iron(III) aminobisphenolate hydroxyquinoline complexes as potential therapeutic agents(The Royal Society, 2019) Matos, Cristina P.; Yildizhan, Yasemin; Adiguzel, Zelal; Pavan, Fernando R.; Campos, Debora L.; Pessoa, Joao Costa; Ferreira, Liliana P.; Tomaz, Ana Isabel; Correia, Isabel; Ayhan, Ceyda Açılan; Faculty Member; School of Medicine; 219658In the quest for therapeutic iron-based metallodrugs, two new mixed-ligand iron(iii) complexes bearing the tripodal aminobisphenolate ligand N,N-bis(3,5-dimethyl-2-hydroxybenzyl)-N-(2-pyridylmethyl)amine (H2L) and hydroxyquinoline co-ligands, 8-hydroxyquinoline (8HQ) or 5-chloro-8-hydroxyquinoline (Cl8HQ), are synthesized, fully characterized and formulated as [Fe(L)(8HQ)] (1) and [Fe(L)(Cl8HQ)] (2), respectively. These high-spin Fe(iii) complexes are stable in aqueous solution in the presence of equimolar amounts of Bovine Serum Albumin (BSA), which indicates a likely binding interaction with the protein. In fact, binding constant log values at pH 7.4 for HSA of 5.08 and 6.35 were obtained for 1 and 2, respectively. Compounds 1 and 2 are cytotoxic against both human triple-negative breast adenocarcinoma (MDA-MB-231) and human cervical carcinoma (HeLa) cancer cells, and the activity is significantly improved by inclusion of the co-ligands 8HQ and Cl8HQ to the precursor complex Fe(L). Moreover, 1 and 2 are more active than 8HQ and Cl8HQ, particularly at lower incubation times tested, 24 and 48 h. Cells treated with the complexes display typical features of apoptosis as assessed by cellular morphology, DNA condensation and TUNEL analysis. COMET assays show that both drug candidates induce genomic damage in both cell lines. The complexes exhibit DNA cleavage activity and DNA damage that may be related to their ability to generate ROS. Overall, data supports that 1 and 2 are both active anticancer drug candidates within the low micromolar range. This is particularly interesting in the case of the breast MDA-MB-231 line, a model for triple-negative breast cancer that is an aggressive form of breast cancer, highly invasive and with limited treatment options and very poor prognosis. Furthermore, both complexes exhibited good anti-Mycobacterium tuberculosis activity, suggesting that 1 and 2 might have a wide spectrum of biological activity and justify further research.Publication Metadata only Structures and anticancer activity of chlorido platinum(II) saccharinate complexes with mono- and dialkylphenylphosphines(Elsevier Science Inc, 2019) İçsel, Ceyda; Yılmaz, Veysel T.; Aygün, Muhittin; Ulukaya, Engin; Animal Laboratory; Cevatemre, Buse; Researcher; Animal Laboratory; N/A; N/Acis-[PtCl(sac)(PPh2Me)(2)] (1), cis-[PtCl(sac)(PPhMe2)(2)] (2), trans-[PtCl(sac)(PPh2Et)(2)] (3) and trans- [PtCl(sac) (PPhEt2)(2)] (4) complexes (sac = saccharinate) were synthesized and characterized by elemental analysis and spectroscopic methods. The structures of 2-4 were determined by X-ray single-crystal diffraction. The interaction of the complexes with DNA was studied various biochemical, biophysical and molecular docking methods. Only the cis-configured complexes (1 and 2) showed nuclease activity and their binding affinity towards DNA was considerably higher than those of their trans-congeners (3 and 4). The chlorido ligand in the cis-configured complexes underwent aquation, making them more reactive towards DNA. Furthermore, 1 and 2 exhibited anticancer potency on breast (MCF-7) and colon (HCT116) cancer cells similar to cisplatin, whereas 3 and 4 were biologicallly inactive. Mechanistic studies on MCF-7 cells showed that higher nuclear uptake, cell cycle arrest at the S phase, dramatically increased DNA double-strand breaks, apoptosis induction, elevated levels of reactive oxygen species (ROS) and high mitochondrial membrane depolarization greatly contribute to the anticancer potency of 1 and 2.Publication Metadata only Switch of thermal expansions triggered by itinerant electrons in isostructural metal trifluorides(American Chemical Society (ACS), 2022) Qin, Feiyu; Wang, Xiaoying; Hu, Lei; Jia, Ning; Gao, Zhibin; Chen, Jun; Ding, Xiangdong; Sun, Jun; Department of Chemistry; Aydemir, Umut; Faculty Member; Department of Chemistry; College of Sciences; 58403Manageable thermal expansion (MTE) of metal trifluorides can be achieved by introducing local structure distortion (LSD) in the negative thermal expansion ScF3. However, an open issue is why isostructural TiF3, free of LSD, exhibits positive thermal expansion. Herein, a combined analysis of synchrotron X-ray diffraction, X-ray pair distribution function, and rigorous first-principles calculations was performed to reveal the important role of itinerant electrons in mediating soft phonons and lattice dynamics. Metallic TiF3 demonstrates itinerant electrons and a suppressed Gru''neisen parameter gamma -20, while insulating ScF3 absence of itinerant electrons has a considerable gamma -120. With increasing electron doping concentrations in ScF3, soft phonons become hardened and the gamma is repressed significantly, identical to TiF3. The presented results update the thermal expansion transition mechanism in framework structure analogues and provide a practical approach to obtaining MTE without inducing sizable structure distortion.