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    Fabrication of Langmuir-Blodgett thin films of calix[4]arenes and their gas sensing properties: Investigation of upper rim para substituent effect
    (Elsevier Science Sa, 2014) Ozmen, Mustafa; Ozbek, Zikriye; Buyukcelebi, Sumeyra; Bayrakci, Mevlut; Ertul, Seref; Ersoz, Mustafa; Capan, Rifat
    This study reports the characterization and organic vapor sensing properties of Langmuir-Blodgett (LB) thin films of calix[4] arene derivatives that contain different numbers of tert butyl groups on their upper rims. Surface pressure-area isotherms show that very stable monolayers are formed at the air-water interface. The LB films are deposited onto different substrates, which allowed us to characterize the films by contact angle measurements, quartz crystal microbalance (QCM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results indicate that good quality, uniform LB films can be prepared with transfer ratios of over 0.95. Meanwhile, our QCM results show that the deposition of LB film layers depends heavily on the number of p-tert-butyl groups and calix[4]arene with four p-tert-butyl groups yields the highest slope with a mass value of 1145 ng per layer. Furthermore, our AFM and SEM studies reveal a dense surface morphology for all prepared LB films. The kinetic response of calix[4]arenes containing p-tert-butyl groups and without p-tert-butyl groups as an LB film to chloroform, benzene, toluene, and ethanol vapors were investigated as a function of time. After attaching tert-butyl groups onto the calix[4]arene structure, the response of LB film to chloroform vapor increased. LB films of compounds 1-4 yield a response to all vapors and more often select chloroform with a larger, faster, and more reproducible response. We thus conclude that these calix[4]arenes could be applied to research concerning vapor sensing devices operating at room temperature. (C) 2013 Elsevier B.V. All rights reserved.
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    Thiol-ene-clickable and emissive carbazole-based polymer networks with tunable colors
    (Elsevier Science Bv, 2016) Doyranli, Ceylan; Buyukcelebi, Sumeyra; Koyuncu, Sermet; Usluer, Ozlem; Kus, Mahmut; Koyuncu, Fatma Baycan
    Band gap tuning and processability of organic materials are significant topics for both scientific research and commercial applications. In this study, we synthesized a series of main chain cross-linkable polymers by thiol-ene click chemistry from N-allyl carbazole and different heterocycles via conventional Suzuki coupling polymerization reaction. The emission color of polymers could be successfully tuned from blue to red by attaching different benzazole-acceptor moieties to the carbazole donor unit. We also investigated the effects of cross-linking with respect to the amount of pentaerythritol tetrakis(3-mercaptopropionate) cross-linker on the optical, electrochemical, and surface morphological properties of the polymer films. The results showed that these polymers can be used as emissive active layers in solution-processable multilayer organic light-emitting diodes. (C) 2016 Published by Elsevier B.V.