A simple method is devised to deposit well-dispersed Pd nanoparticles on multi-walled carbon nanotubes (CNTs). Pd nanoparticles (1–3 nm) prepared in ethanol were transferred to toluene solution and modified by organic molecule benzyl mercaptan which acts as a cross linker between Pd nanoparticles and CNTs. The morphology and structure of the resulting Pd/CNT nanocomposite were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that Pd nanoparticles were highly dispersed and effectively anchored on CNTs. The excellent electrocatalytic activity of the Pd/CNT nanocomposite for the oxidation of hydrazine was demonstrated by cyclic voltammetry.

Cyclic voltammetric investigation of calcium dobesilate (CD) in aqueous acid media was carried out by using an ordered mesoporous carbon-modified pyrolytic graphite electrode (OMC/PGE). A pair of well-defined redox peaks of CD was observed at the OMC/PGE, showing its good elelctrochemial response towards CD. The anodic current is linear with CD concentration in the range of 1.0 × 10−7–1.3 × 10−3 mol L−1, with a detection limit of 4.0 × 10−8 mol L−1. Meanwhile, the proposed electrode can avoid some interference coexisting with CD, such as uric acid, serotonin, and ascorbic acid. The proposed method can be potentially applied for selective electrochemical sensing of CD in physiological condition.

A new ordered mesoporous carbon (OMC) modified pyrolytic graphite electrode (PGE) was prepared to investigate electrochemical behavior of the anticancer drug tirapazamine (TPZ). Compared to the bare PGE, the modified electrode showed an excellent electrochemical response to TPZ. The anodic peak current (Ipa) of TPZ at the OMC/PGE is 180-fold higher than that of the bare PGE. The Ipa is proportional with TPZ concentration in the range of 5.0 × 10−11 to 1.5 × 10−5 mol L−1. The linear regression equations are Ipa (μA) = 0.0000044 + 16.928CTPZ (μmol L−1), with a detection limit (S/N = 3) of 2.0 × 10−11 mol L−1. This proposed method can be potentially used for ultrasensitive electrochemical sensing of TPZ in physiological condition.

A new palladium nanoparticle functionalized multi-wall carbon nanotubes (nano-Pd/CNTs) modified pyrolytic graphite electrode (PGE) has been fabricated for electrochemical sensing of calcium dobesilate (CD) in pharmaceutical capsules. The nano-Pd/CNTs were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The nano-Pd/CNTs composite showed a strong electrocatalytic property for CD. The anodic peak current is 6-fold than that obtained in bare PGE and the oxidation potential has an obvious shift to negative. The anodic peak current is proportional to the concentration of CD in the range of 1.0 × 10−7 to 7.0 × 10−4 mol L−1, with a linear relative coefficient r = 0.999 and a detection limit 4.0 × 10−8 mol L−1 (S/N = 3). This kind of electrode shows good stability, sensitivity, reproducibility, large linear range and low detection limit towards electrochemical determination of CD. The proposed method provides a selective and sensitive electrochemical sensor of calcium dobesilate.

Some acyl-thiourea derivatives containing isatin group were synthesized and their interactions with anions were investigated using UV–vis spectroscopy and 1H NMR titrations in DMSO and DMSO-d6, respectively. These compounds have a same molecular framework, functionalising with different groups lead to different anion binding strength of these receptors. Receptor 1 showed a higher binding affinity for AcO− than for F−, due to the cooperative multiple hydrogen bond interactions of AcO− with the acyl-thiourea group and N–H group in the indole unit of receptor 1. Displacing the N–H proton in the indole unit with –CH3 group, receptor 2 showed no obviously discriminative responses for F−, AcO− and H2PO4− due to lack of such additional binding. In the case of receptor 3, which was functionalised with strong electron-withdrawing group, it showed selectively chromogenic response for F− based on double deprotonation of the receptor in DMSO, whereas AcO− and H2PO4− induced single deprotonation only.

A new gold nanoparticles-modified electrode (GNP/LC/GCE) was fabricated by self-assembling gold nanoparticles to the surface of the l-cysteine-modified glassy carbon electrode. The modified electrode showed an excellent character for electrocatalytic oxidization of uric acid (UA) and ascorbic acid (AA) with a 0.306 V separation of both peaks, while the bare GC electrode only gave an overlapped and broad oxidation peak. The anodic currents of UA and AA on the modified electrode were 6- and 2.5-fold to that of the bare GCE, respectively. Using differential pulse voltammetry (DPV), a highly selective and simultaneous determination of UA and AA has been explored at the modified electrode. DPV peak currents of UA and AA increased linearly with their concentration at the range of 6.0 × 10−7 to 8.5 × 10−4 mol L−1 and 8.0 × 10−6 to 5.5 × 10−3 mol L−1, respectively. The proposed method was applied for the detection of UA and AA in human urine with satisfactory result.

Quinonehydrazone compound 2, as a new chromogenic anion sensor, can selectively detect AcO− over F− and other anions in mixed acetonitrile–water media. The deprotonation of the N–H proton of the sensor is responsible for the drastic color change. An acidic C–H group in the receptor, probably acting as an accessorial binding site, is essential to the selectivity and affinity for sensing the acetate anions.

The solution binding properties of calix[4]pyrroles with anion (added as tetraalkylammonium salts) were investigated using UV–vis spectroscopic techniques. The obvious red-shift of absorption maximum band of calix[4]pyrrole in EtOH in the presence of the tetramethylammonium (TMA+) or tetraethylammonium (TEA+) salts were observed. These results displayed in electronic absorption spectra indicated calix[4]pyrrole receptors linking anionic species through multiple hydrogen bonding interactions are capable of using the periphery electron-rich “walls” for selectively binding electron-deficient tetraalkylammonium cation subunits by cation-π charge–transfer interaction. It was seen that the stability of the calix[4]pyrrole–anion complex depends strongly on the cation. The meso-alkyl groups of the calix[4]pyrrole, the affinity for the anion subunits and the structure of tetraalkylammonium cations have considerable effects on the formation of cation-π charge–transfer interaction.

Quinonehydrazone compound 2, as a new chromogenic anion sensor, can selectively detect AcO− over F− and other anions in mixed acetonitrile–water media. The deprotonation of the N–H proton of the sensor is responsible for the drastic color change. An acidic C–H group in the receptor, probably acting as an accessorial binding site, is essential to the selectivity and affinity for sensing the acetate anions.