Organocatalytic Atroposelective Construction of Axially Chiral Nonsymmetric Biaryltriols and Their Applications on Asymmetric Synthesis and Heavy Metal Ion Detection

An organocatalytic methodology toward the atroposelective construction of axially chiral nonsymmetric biaryltriols has been successfully developed. Quinine-derived thiourea-catalyzed intramolecular reaction through VQM (vinylidene ortho-quinone methides) intermediate enabled efficient access to...

Design and development of electrochemical potentiostat circuit for the sensing of toxic cadmium and lead ions in soil

Contamination of heavy metal ions in soils has proved to be a significant concern and it poses many health risks. Conventional methods which was used for the identification and detection of heavy metals were non portable and not suitable for onsite applications. The proposed work is to design a low cost electronic circuit for the detection of cadmium and lead ions in soil sample. A screen printed electrode and a Glassy Carbon electrode are interfaced with a designed circuit for electrochemical analysis. Anodic stripping voltammetry is the theory behind the metal ion detection process. Based on the current peaks observed in voltammetry process, the presence of lead and cadmium in given sample can be determined. A voltage controlled circuit is designed to perform the functions of Ec-Lab which makes this system portable. The results are compared with that of the potentiostat device to evaluate the accuracy of the designed circuit.

Preparation of Large Conjugated Polybenzimidazole Fluorescent Materials and Their Application in Metal Ion Detection

A new type of conjugated polybenzimidazole (CPBI) was synthesized through a simple polycondensation reaction without metal catalysis, and N-alkylation modification was carried out to solve the problems of solubility and fluorescence properties. A series of nano-microsphere polymers CPBIn with large conjugation, good solubility, and strong fluorescence has been successfully used as “turn-off” fluorescent probes for the first time. The results show that, under suitable N-alkylation conditions, the obtained CPBIn can be used as a highly sensitive and selective fluorescent probe for the detection of Cu2+ and Zn2+ at the same time, and their detection limits are both nM levels. In addition, CPBI2 can be designed as an ultra-sensitive IMPLICATION logic gate at the molecular level, cyclically detecting Cu2+. With the test paper containing CPBI2, easy and quick on-site detection can be achieved. This research provides a new idea for the brief synthesis of multifunctional materials.

Top-Down N-Doped Carbon Quantum Dots for Multiple Purposes: Heavy Metal Detection and Intracellular Fluorescence

In the present study, we successfully synthesized N-doped carbon quantum dots (N-CQDs) using a top-down approach, i.e., hydroxyl radical opening of fullerene with hydrogen peroxide, in basic ambient using ammonia for two different reaction times. The ensuing characterization via dynamic light scattering, SEM, and IR spectroscopy revealed a size control that was dependent on the reaction time, as well as a more pronounced -NH2 functionalization. The N-CQDs were probed for metal ion detection in aqueous solutions and during bioimaging and displayed a Cr3+ and Cu2+ selectivity shift at a higher degree of -NH2 functionalization, as well as HEK-293 cell nuclei marking.