Chiral salen Mn(III) complex-based enantioselective potentiometric sensor for l-mandelic acid

Design of surface nanostructures for chirality sensing based on quartz crystal microbalance

Quartz crystal microbalance (QCM) has been widely used for various sensing applications, including chirality detection due to the high sensitivity to nanogram or picogram mass changes, fast response, real-time detection, easy operation, suitability in different media, and low experimental cost. The sensing performance of QCM is dependent on the surface design of the recognition layers. Various strategies have been employed for studying the relationship between the structural features and the specific detection of chiral isomers. This review provides an overview of the construction of chiral sensing layers by various nanostructures and materials in the QCM system, which include organic molecules, supermolecular assemblies, inorganic nanostructures, and metal surfaces. The sensing mechanisms based on these surface nanostructures and the related potentials for chiral detection by the QCM system are also summarized.

Synthesis, spectral studies, antioxidant and antibacterial evaluation of aromatic nitro and halogenated tetradentate Schiff bases

Herein, we report the synthesis, characterization, and biological properties of eleven (3a-3k) novel Schiff bases. The spectral data of FT-IR, ¹H NMR, ¹³C NMR, and LC-MS are associated with these synthesized compounds. From the FT-IR analysis, we confirmed the azomethine (-C=N-) group and from ¹H NMR data, the phenolic –OH proton is appeared at range δ 13.92–14.09ppm due to hydrogen bonding. The LC-MS analysis agreed with molecular ion peaks of synthesized Schiff bases. To evaluate the antibacterial activity of newly synthesized compounds were screened against b. licheniformis, b. species, e. coli, and s. aureus. Furthermore, the antioxidant activity was investigated by two methods 2,2-diphenyl-1-picryl hydrazyl (DPPH) and hydroxyl radical scavenging methods. The (-NO₂,-Cl,-Br,-I) substituted compounds have shown good antibacterial activity against tested organisms. Also, these compounds were exhibited higher antioxidant activity by given methods.

A disposable dual-signal enantioselective electrochemical sensor based on stereogenic porous chiral carbon nanotubes hydrogel

As the highest form of molecular recognition, the chiral molecular recognition is the most difficult measurements. Herein, a disposable dual-signal enantioselective platform was fabricated based on stereoscopic porous chiral carbon nanotubes hydrogel modified screen printed electrode. This kind of chiral hydrogel was prepared by a simple heating method with l-cysteine and chiral single-walled carbon nanotubes of chirality (6,5), and its dispersion and morphology were characterized by several techniques including scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The stereogenic chiral interface was successfully employed to discriminate mandelic acid enantiomers via both oxidation peak intensity and peak potential value of cyclic voltammetry. The chiral recognition mechanism was discussed specifically, which resulted from the formation of an efficient three-dimensional chiral nanospace. The inherent chirality of chiral carbon nanotubes hydrogel, together with their orderly spatial arrangement, can significantly improve the efficiency of chiral recognition compared with traditional electrochemical chiral sensors. As a novel chiral sensing interface, such chiral carbon nanotubes hydrogel was simple to prepare, fast to operate, with good sensitivity and excellent stability for the construction of efficient and practical electrochemical chiral sensors.

An Enantioselective Potentiometric Sensor for 2-Amino-1-Butanol Based on Chiral Porous Organic Cage CC3-R

Porous organic cages (POCs) have attracted extensive attention due to their unique structures and tremendous application potential in numerous areas. In this study, an enantioselective potentiometric sensor composed of a polyvinyl chloride (PVC) membrane electrode modified with CC3-R POC material was used for the recognition of enantiomers of 2-amino-1-butanol. After optimisation, the developed sensor exhibited enantioselectivity toward S-2-amino-1-butanol ( log K S , R P o t = -0.98) with acceptable sensitivity, and a near-Nernstian response of 25.8 ± 0.3 mV/decade within a pH range of 6.0⁻9.0.

Spectroscopic, crystal structural and electrochemical studies of zinc(II)-Schiff base complex obtained from 2,3-diaminobenzene and 2-hydroxy naphthaldehyde

Mononuclear zinc(II) complex, [Zn(II)L], where L is a dianionic ligand, has been synthesized and characterized by elemental analysis, electronic, IR and NMR [(1)H, (13)C, DEPT, (1)H-(1)H COSY, ROESY, HSQC and HMBC] spectroscopic techniques. Structural analysis of the complex by single crystal X-ray crystallography shows the presence of a distorted square planar coordination geometry (NNOO) of the metal center. The crystal of the title complex C28H18N2O2Zn belongs to the orthorhombic system with space group Pmn21. Electrochemical behavior of the Zn(II)L complex has been investigated by cyclic voltammetry on glassy carbon and platinum electrodes in DMF at 100 mV/s scan rate.