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    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, Matem
    In 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.
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    A Novel Calix[4]arene Thiourea Decorated with 2-(2-Aminophenyl)benzothiazole Moiety as Highly Selective Chemical Gas Sensor for Dichloromethane Vapor
    (Wiley-V C H Verlag Gmbh, 2021) Durmaz, Mustafa; Acikbas, Yaser; Bozkurt, Selahattin; Capan, Rifat; Erdogan, Matem; Ozkaya, Cansu
    A newly synthesized calix[4]arene thiourea derivative decorated with 2-(2-aminophenyl)benzothiazole unit is selected to take part important role in host-guest interactions of the macrocyclic molecules. p-tert-butylcalix[4]arene dithiourea (C[4]-DT) Langmuir-Blodgett (LB) thin films are prepared and characterized to develop a new sensing element for the detection of seven different organic vapors (dichloromethane, chloroform, acetone, benzene, carbon tetrachloride, toluene and m-xylene). The preparation of C[4]-DT-based thin films onto the different substrates was successfully and uniformly achieved with linear regressions of 0.9971 and 0.9954 for coating onto quartz glass and quartz crystal, respectively. The frequency shift (61.01 Hz) and the mass deposited onto quartz crystal (969.80 ng) were calculated for each layer. The swelling dynamics of C[4]-DT QCM chemical sensor was also illuminated by developing the early time Fick's diffusion equation. The sensing measurements can be concluded that owing to its high sensitivity (6.63 Hz/ppm), fast response and low detection limit (0.45 ppm), this proposed C[4]-DT LB coated sensor is expected to be promising alternative chemical sensor for detection of DCM vapor.
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    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, Rifat
    25,27-(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.