https://hdl.handle.net/20.500.12809/80 2026-04-04T15:07:41Z 2026-04-04T15:07:41Z Acar, Yasemin Coban, Mustafa Burak Gungor, Elif Kara Subaşat, Hülya https://hdl.handle.net/20.500.12809/704 2021-04-12T20:45:03Z 2020-01-01T00:00:00Z

Two New NIR Luminescencent Er(III) Coordination Polymers with Potential Application Optical Amplification Devices Acar, Yasemin; Coban, Mustafa Burak; Gungor, Elif; Kara Subaşat, Hülya Two new Er(III)-cluster-based coordination compounds have been synthesized by hydrothermal technique using monosodium 2-sulfoterephthalate (2-stp) and 4,4 '-bipyridyl (4,4 '-bpy) ligands. Depending on synthetic procedure, monomeric and polymeric Er(III) products, isolated as {[Er(2-stp)(2)(H2O)(6)]0.2(4,4 '-bipy)0.4(H2O)}, 1 and {[Er(2-stp)(4,4 '-bipy)(H2O)](H2O)}(n), 2. Both compounds have been characterized by elemental analysis, FT-IR, UV-visible and single-crystal X-ray diffraction and solid-state photoluminescence. The X-ray structure analyses show that Er atom is surrounded by two 2-stp ligands which have monodentate connection mode forming a monomeric structure in compound 1. However, in compound 2, Er atoms are coordinated by four bridging 2-stp ligands which adopt a hexadentate connection mode to form a central symmetrically dimeric building unit. The photoluminescence spectrums of the compounds have been exhibited intense blue emission for 1 and cyan-blue emission for 2. The band observed in NIR region at 1532 nm (for 1) and 1540 nm (for 2) are the typical Er-III emission. The excellent NIR luminescent properties, indicating their promising potential applications as gain medium materials in optical amplification devices. KARA, Hulya/0000-0002-2032-8930; WOS: 000513242600009

2020-01-01T00:00:00Z Hopa, Cigdem Kara Subaşat, Hülya Aybey, Aynur https://hdl.handle.net/20.500.12809/588 2021-04-12T20:44:58Z 2020-01-01T00:00:00Z

Synthesis, structural characterization and biological evaluation of novel mixed-ligand Co(II) complexes as quorum sensing inhibitory agent Hopa, Cigdem; Kara Subaşat, Hülya; Aybey, Aynur Antibiotic resistance is one of the biggest health problems of the twenty-first century. In order to cope with this global problem, alternative preventive strategies such as quorum sensing interruption are needed. Therefore, it is very important to develop new compounds with anti-quorum sensing activity. Here we present the synthesis and structural characterization of two new Co (II) complexes; [Co(btmpp)(NCO)(2)], 1 and [Co(btmpp)(NCSe)(2)], 2 (where btmpp is: 2,6-bis(3,4,5-trimethylpyrazolyl) pyridine). The crystal structures of both complexes is determined using single-crystal X-ray diffraction. The coordination environment of Co(II) atoms can be described as a distorted square pyramidal geometry. Both complexes is screened for antibacterial activities against Gram-positive (B. substilis) and Gram-negative (P. aeruginosa, S. typhimurium, S. sonnei, Y. enterocolitica) bacterial strains. The effects of these complexes on QS-regulated behaviors of bacteria such as swarming, and biofilm formation is also examined. All bacteria are found to be more sensitive to complex 2 than complex 1. (C) 2019 Elsevier B.V. All rights reserved. KARA, Hulya/0000-0002-2032-8930; WOS: 000501486700113

2020-01-01T00:00:00Z Myronyuk, O. V. Raks, V. A. Baklan, D. V. Barrat, S. Arranda, L. Yezhov, S. Kara Subaşat, Hülya https://hdl.handle.net/20.500.12809/505 2021-04-12T20:44:55Z 2020-01-01T00:00:00Z

Aspects of the reduction of the coating fire resistance by the use of nanosized additives Myronyuk, O. V.; Raks, V. A.; Baklan, D. V.; Barrat, S.; Arranda, L.; Yezhov, S.; Kara Subaşat, Hülya As a new generation fire-resistant material, the intumescent coating has significant advantages over conventional fire protection materials. The applications of the intumescent coating have changed widely and have dominated the fire engineering market. In this study, intumescent coatings with different nanosized additives such as fumed silica, organo-montmorillonite, aluminum oxide and titanium dioxide were investigated. It was shown that organically modified montmorillonite and hydrophobized silica reduced fire resistance properties of intumescent coatings. The reason for such decrease is the shift of the expansion processes to higher temperatures. This phenomenon increases the time of direct heating of the substrate. Moreover, it was established that the minor concentrations of organically modified montmorillonite could significantly change the structure of coatings and increase the specific heat insulation properties of the carbon foams. Such an effect was also observed in the case of the use of hydrophobic silica, but to a lesser extent. It was shown that nanosized additives have effect on the expansion factor and the foam structure. It was suggested that this effect could be explained by the complex influence of the nanoparticles on the bubble growth processes through the melt viscosity modification. WOS: 000529723700002

2020-01-01T00:00:00Z Gungor, Elif Kara Subaşat, Hülya https://hdl.handle.net/20.500.12809/476 2021-04-12T20:44:54Z 2020-01-01T00:00:00Z

Ferromagnetic coupling in two tetranuclear Ni(II) complexes with cubane-like Ni-4(mu(3)-O)(4) core: Structure, spectroscopic and luminescence properties Gungor, Elif; Kara Subaşat, Hülya Two new tetranuclear [Ni-4(L1)(4)(MeOH)(4)] (1) and [Ni-4(L2)(4)(EtOH)(MeOH)(H2O)]1 center dot H2O (2) complexes have been synthesized by solvothermal method. We here report the spectroscopic, structural, photoluminescence and magnetic properties of both complexes. Complex 1 and 2 exhibit a cubane-like Ni4O4 structure. All Ni(II) center has a slightly distorted octahedral geometry. The optical properties of 1 and 2 have been analyzed by photoluminescence spectra obtained in the visible region. Variable-temperature (2-300 K) magnetic studies have been analyzed by using the Heisenberg Hamiltonian model with 2J exchange pathways. The best-fit parameters in analysis of the magnetic data are found as J(1) = -2.38 cm(-1), J(2) = +5.43 cm(-1), g = 2.2, N-x, = 0.08 for 1, J(1) = -2.34 cm(-1), J(2) = +4.90 cm(-1), g = 2.2 and N-alpha = 0.11 for 2. These results are shown dominant ferromagnetic interactions between Ni(II) centers. Finally, the strong luminescence emission of both complexes makes them potentially useful photoactive material in developing optical and electronic materials. (C) 2020 Elsevier B.V. All rights reserved. WOS: 000519189500017

2020-01-01T00:00:00Z