Synthesis and Complexation Properties Towards Metal Ions of New Tri-substituted Thiacalix[4]arenes

International audienceNew thiacalix[4]arenes appended with three amide functions have been prepared. Their conformations have been solved thanks to 1H NMR 2D COSY and NOESY. The complexation ability of these ligands towards various metal ions (Cd2+, Pb2+, Pd2+; Ni2+, Hg2+, Hg+, Ag+, Zn2+ and Cu2+) has been investigated by UV-vis absorption and the stoichiometry of the metal-ligand complexes was determine

Detection of heavy metals by an optical fiber sensor with a sensitive cladding including a new chromogenic calix[4]arene molecule

International audienceIndustrial processes introduce up to a million different pollutants into the atmosphere and the aquatic ecosystem. Heavy metals are one group of these substances, although not all of them are considered harmful to humans. The molecule of calixarene is a macrocycle used effectively in the complexation of the heavy metal pollutants (nickel, copper(II)...). The goal of this work is to condition a new chromogenic calix[4]arene molecule to elaborate an optical fiber sensor able to detect this type of pollutant. The light power increases when the concentration of the ion increases. The optimum pH for heavy metal ion detection is found to be 5. The influence of the unclad length on the response sensor is studied and the optimum length is found to be around 3 cm. The limit of detection reached is of the order of 1 mu M, 10(-3) mu M and 10(-4) mu M for copper(II), cobalt(II) and cadmium(II) cations respectively

High Sensitive Surface Plasmon Resonance (SPR) Sensor Based on Modified Calix(4)arene Self Assembled Monolayer for Cadmium Ions Detection

International audienceIn this work, a new chromogenic calix(4) arene was functionalized onto self assembled monolayer (SAM) of cysteamine for cadmium ions detection and tested by using SPR measurement. The functionalization of modified SPR sensor is based on the oxidation of calixarene-SAM alcohol group to quinone. Four interfering ions were used Cu2+, Co2+, Mg2+ and Ca2+. pH of sensor in which the sensitivity of sensor is higher was optimized for cadmium ions and detection of ions was made in basic solution. Detection limit reached for Cd2+ is lower than 10(-11) M with a dynamic response time of about 16 s when changing from 10(-6) M cadmium to 10(-5) M

Nanostructural, optical and electrical properties of vacuum evaporated films of an azo-calix[4]arene derivative

International audienceThe nanomorphology, optical and electrical properties of vacuum-deposited azo-calix[4]arene thin films have been investigated. The nanostructured films exhibit absorption spectra with a resolved electronic structure in the UV-vis and a blue photoluminescence emission at about 430 nm independent of the excitation wavelength. The current-voltage (I-V) characteristics of ITO/azo-calix[4]arene/Au devices have been studied. The I-V dependence follows a power law, I ∝ Vm, which is typical of a space-charge-limited current. Moreover, from the I-V measurements, we have estimated the effective hole mobility of not, vert, similar7.5 × 10−6 cm2/V s in the vacuum-deposited azo-calix[4]arene thin films. Using impedance spectroscopy over a broad frequency range, i.e. 100 Hz to 10 MHz, it is found that the ac behavior of an ITO/azo-calix[4]arene/Au device shows several features, described by the simple RC circuit representing an undepleted bulk region. Values of the electrical circuit parameters deduced from fitting experimental data to the model have given a dielectric relaxation time in the millisecond range

Transport mechanism and trap distribution in ITO/azo-calix[4]arene derivative/Al diode structure

International audienceElectrical measurements have been performed on spin-coated azo-calix[4]arene derivative on pre-cleaned indium thin oxide (ITO) substrates using current versus voltage, capacitance versus voltage and impedance spectroscopy measurements. The nature of trap states in single layer ITO/azo-calix[4]arene derivative/Al organic diodes has also been investigated. The energy band gap of the thin film containing calixarene derivative has been measured by UV–Vis absorption spectroscopy and is about 2.77 eV. The current–voltage characteristics have shown ohmic behavior at low voltages. At high applied bias the I–V characteristics can be successfully modeled by space-charge limited current (SCLC) theory. The impedance dependence of bias and frequency is discussed in terms of the presence of a depletion layer in the bulk. The device is accurately modeled, in a range of frequency between 100 Hz and 1 MHz, as a single parallel resistor and capacitor network placed in series with a resistance. Their values deduced from fitting experimental data to the model have given a dielectric relaxation time in the ms range and an exponential trap distributio

Nanostructural, optical and electrical properties of vacuum evaporated films of an azo-calix[4]arene derivative

International audienceThe nanomorphology, optical and electrical properties of vacuum-deposited azo-calix[4]arene thin films have been investigated. The nanostructured films exhibit absorption spectra with a resolved electronic structure in the UV-vis and a blue photoluminescence emission at about 430 nm independent of the excitation wavelength. The current-voltage (I-V) characteristics of ITO/azo-calix[4]arene/Au devices have been studied. The I-V dependence follows a power law, I ∝ Vm, which is typical of a space-charge-limited current. Moreover, from the I-V measurements, we have estimated the effective hole mobility of not, vert, similar7.5 × 10−6 cm2/V s in the vacuum-deposited azo-calix[4]arene thin films. Using impedance spectroscopy over a broad frequency range, i.e. 100 Hz to 10 MHz, it is found that the ac behavior of an ITO/azo-calix[4]arene/Au device shows several features, described by the simple RC circuit representing an undepleted bulk region. Values of the electrical circuit parameters deduced from fitting experimental data to the model have given a dielectric relaxation time in the millisecond range