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Öğe Fabrication and characterization of calix[4]arene Langmuir-Blodgett thin film for gas sensing applications(Springer, 2017) Acikbas, Yaser; Bozkurt, Selahattin; Halay, Erkan; Capan, Rifat; Guloglu, Mehmet Levent; Sirit, Abdulkadir; Erdogan, MatemIn this work, the Langmuir-Blodgett (LB) technique was applied onto the different substrates such as quartz, quartz crystals and gold coated glass for fabricating LB thin films with 25,27-(Dipropylmorpholinoacetamido)-26,28-dihydroxycalix[4]arene. The characteristics of the calix[4]arene LB films were evaluated by UV-Vis, atomic force microscopy (AFM), quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements. The mass deposited on the quartz crystal per bilayer was predicted as 2028.80 ng (7.65 ng mm(-2)) for the calix[4]arene LB film. The sensing abilities of this LB film towards the development of room temperature organic vapor sensing devices were also examined. QCM and SPR systems were fixed to investigate vapor sensing performance of macrocyclic LB films during exposure to volatile organic compounds (VOCs). The macrocyclic LB thin films were more sensitive to dichloromethane than other vapors. The sensitivity and detection limit values of the calix[4]arene QCM sensor to dichloromethane vapor were calculated as 2.023 Hz ppm(-1) and 1.482 ppm, respectively. The sensitivities of the calix[4]arene LB films against organic vapors can be explained with the host-guest interaction between the cavity of molecule and the organic vapor molecules. It is determined that the calix[4]arene LB film is more sensitive to dichloromethane than other vapors at room temperature and the calix[4]arene is a promising material serving as a vapor sensing device.Öğe A novel turn-on fluorometric reporter-spacer-receptor chemosensor based on calix[4]arene scaffold for detection of cyanate anion(Wiley, 2021) Bozkurt, Selahattin; Halay, Erkan; Durmaz, Mustafa; Topkafa, Mustafa; Ceylan, OzgurHerein, a novel calix[4]arene compound, which was modified by the 2-(2-aminophenyl)benzothiazole fragment with cyanate recognition function was designed based on the reporter-spacer-receptor sensing system. The construction was done via two-step reaction, and the desired sensor 4 was characterized by FT-IR, H-1-, C-13-NMR, and fluorescence spectroscopy along with HRMS data. The sensor candidate showed distinct fluorometric cyanate detection by means of reporter feature of selected benzothiazole constituent. In the presence of cyanate, the sensor gave a turn-on-type fluorescence at 482 nm with a large stokes' shift. Furthermore, it was observed that our fluoroionophore 4 is highly selective toward cyanate over remaining anions such as sulfate, phosphate, fluoride, chloride, bromide, iodide, chlorate, and nitrate in 10% aqueous solution of DMSO. The 1:2 stoichiometric ratio of the 4-cyanate complex was given the best fit with Job's plot based on the titration data. The association constant (K-a) of sensor 4 with cyanate is determined to be 1.64 x 10(5) M-2. The obtained limit of detection (LOD) value for cyanate anion, 312 nM, clearly revealed the remarkable sensitivity of the chemosensor 4. This supramolecular method provides a highly adaptive technique for the detection of cyanate and so cyanide ions by current international standard methods.Öğe Optical and Vapor Sensing Properties of Calix[4]arene Langmuir-Blodgett Thin Films with Host-Guest Principles(Taylor & Francis Inc, 2018) Acikbas, Yaser; Bozkurt, Selahattin; Erdogan, Matem; Halay, Erkan; Sirit, Abdulkadir; Capan, Rifat25,27-(Dipropylmorpholinoacetamido)-26,28-dihydroxycalix[4]arene was used as a chemical sensor material in this work. The calix[4]arene LB thin films were prepared onto a gold-coated glass and quartz glass substrates to fabricate a thin film chemical sensor element. Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques were used to characterize all the calix[4]arene LB thin films. The film thickness and the refractive index of thin films can be evaluated with the fitted experimental SPR datas. The refractive index and the thickness per monolayer of LB films were determined as a 1.58 +/- 0.04 and 1.27 +/- 0.09nm, respectively. The calix[4]arene LB thin film chemical sensor element was exposed to dichloromethane, chloroform, benzene and toluene vapors. The SPR kinetic measurements displayed that, the photodetector response change, I-rf for saturated dichloromethane vapor is much larger than the other vapors with the I-rf value of 48 au and the diffusion coefficient value of 5.1 x 10(-16) cm(2)s(-1). Swelling process was analyzed by well known Fick's Equations. In this approach diffusion coefficients for swelling were conformed to the square root of time and were correlated with the volatile organic compounds. Our results showed that calix[4]arene thin film has a highly selective with a large response to dichloromethane vapor.Öğe Recent applications of chiral calixarenes in asymmetric catalysis(Beilstein-Institut, 2018) Durmaz, Mustafa; Halay, Erkan; Bozkurt, SelahattinThe use of calixarenes in asymmetric catalysis is receiving increasing attention due to their tunable three-dimensional molecular platforms along with their easy syntheses and versatile modification at the upper and lower rims. This review summarizes the recent progress of synthesis and use of chiral calixarenes in asymmetric syntheses which emerged later than 2010.
