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A photoelectrochemical sensor for sulfamethoxazole (SMX) detection was prepared by a simple spin coating based on [N(CH3)4]2CoCl2Br2. The prepared membrane was broadly characterized using different analytical techniques to examine its morphological, wettability, electrochemical, and optical properties. In addition, the interaction mechanism between [N(CH3)4]2CoCl2Br2 and the antibiotic was determinated using absorbance and fluorescence measurements. The impedimetric sensor has exhibited good response towards SMX presenting remarkable limit of detection (LOD) of 2.5 × 10–12 M and limit of quantification (LOQ) of 8.3 × 10–12 M in darkness. Under illumination, LOD and LOQ values have decreased to be 6.3 × 10–13 M and 2.1 × 10–12 M, respectively. The recognition capability has correlated linearly with the SMX concentration in the range of 10–11–10–5 M under the two conditions. Finally, the sensitive thin film has presented high selectivity towards the cibled antibiotic, as well as good regeneration, repeatability and reproducibility. [ABSTRACT FROM AUTHOR]

This study describes an investigation of the sensitivity of the azo-calix[4]arene/poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS) thin film deposited on the indium tin oxide (ITO) electrode surface toward aluminum ions (Al) under light excitation. Thin films were deposited by the spin-coating technique. Adhesion of these films to the ITO surface was highlighted by performing contact angle measurements. Then, interfaces of the azo-calix[4]arene/PEDOT:PSS thin film were characterized by impedance measurements using electrochemical impedance spectroscopy. Obtained impedance spectra were fitted using an equivalent circuit. Finally, evolutions of the different components of this circuit were studied. These evolutions show that the sensitivity of the azo-calix[4]arene/PEDOT:PSS/ITO electrode is remarkably improved under illumination. [ABSTRACT FROM AUTHOR]

Highlights: [•] We elaborate thin films based on MEH–PPV and MEH–PPV/β-ketoimine calix[4]arene. [•] We study the electric and dielectric characteristics of thin films. [•] We investigate the sensing properties of thin films for Cu2+ and Na+. [Copyright &y& Elsevier]

Abstract: Optical, electrical and ion sensing properties of β-ketoimine calix[4]arene thin films have been investigated. These calix[4]arene derivative films exhibit absorption spectra with a resolved electronic structure in the UV–vis and the energy gap was found to be 3.65eV. Electrical properties of ITO/β-ketoimine calix[4]arene/Al devices have been investigated by I–V characteristics and impedance spectroscopy measurements. The conduction is governed by space-charge-limited current (SCLC) mechanism. The impedance spectroscopy study showed a hopping transport process, a typical behavior of disordered materials. The device was modeled by a single parallel resistor and capacitor network in series with a resistance. The β-ketoimine calix[4]arene was used for the conception of the novel optical chemical sensor and the detection of Cu2+ ions was monitored by UV–visible spectroscopy. The linear dynamic range for the determination of Cu2+ has been 10−5–10−3.7 M with a detection limit of 10−5 M. The characteristics of this optode such as regeneration, repeatability, reproducibility, short-term stability, life time and ion selectivity have been discussed. [Copyright &y& Elsevier]

Abstract: Conducting polymer can be used as the polymer matrix of the ion sensitive membrane (containing electroactive sites), which would exhibit intrinsic mixed ionic and electronic conductivity. In this work, a soluble poly(p-phenylene vinylene) derivative (MEH-PPV) has been used as the electroconducting polymer to immobilize the ß-ketoimine calix[4]arene derivative. Indium-thin oxide (ITO) electrode coated with the thin films of MEH-PPV and composite MEH-PPV/ß-ketoimine Cal[4] are designed for the determination of trace amounts of Hg2+ ions. Surface morphology properties were examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presented results show that the incorporation of calixarene derivative into MEH-PPV polymer improved the surface smoothness. Contact angle measurements were used to study hydrophobicity and surface energy properties of thin films. We observed that the best adhesion on the ITO surface is for the MEH-PPV/ß-ketoimine Cal[4] surface due to the presence of (OH) groups coming from the molecules of derivative calix[4]arene. Thin films were characterized by electrochemical impedance spectroscopy (EIS) in the dark and under illumination. The impedance behavior of the modified electrodes is modeled by an equivalent electrical circuit using the Z-View software. From the impedance plots, the bulk resistance and ionic conductivity of the membranes is an important factor determining the ability of ions to pass across the membrane. Marked differences in the ionic conductivity are observed as a function of the light excitation. The charge transfer processes at the electrode/electrolyte interface was carefully examined in the dark and under illumination. Optical excitation of both membranes revealed that the sensing activity of the MEH-PPV/ß-ketoimine Cal[4] modified electrode can improve the measuring sensitivity of Hg2+ ions compared to the MEH-PPV modified electrode. [Copyright &y& Elsevier]

This study focuses on the morphological, electrical and dielectric properties of chromogenic calix[4]arene amide combined with Single-Walled Carbon Nanotubes (SWCNTs). The effects of SWCNTs addition on the performance of the formed nanocomposite material were studied. After the dispersion process, the spin-coated nanocomposite thin films were prepared over indium tin oxide-coated glass substrates. Using scanning electron microscopy, morphological features and surface roughness were examined before and after SWCNTs loading on the chromogenic calix[4]arene amide. In addition, the charge carrier transport properties and conduction mechanism of the chromogenic calix[4]arene amide/SWCNT thin films have been studied by using current–voltage (I–V) characteristics and dielectric spectroscopy technique. The experimental results have shown a significantly enhancement of conductivity and dielectric properties of the nanocomposite thin film with increasing SWCNTs reinforcement. Experimental results were theoretically fitted corresponding to an equivalent circuit aiming to reveal dielectric parameters of the nanocomposite devices. Finally, these prepared nanocomposite films have potential applications in nanoelectronic and sensing devices. [ABSTRACT FROM AUTHOR]