Contaminants like heavy metals in water bodies pose serious risks to human health and ecosystems, often leading to acute and chronic disorders, including cancer and organ damage. Understanding water contamination is vital for sustainable development. A biosensor is a biocompatible, sustainable device that can detect heavy metal ions. To do this, we used a hydrothermal process to produce nitrogen-doped carbon dots (NCDs) from the plant Brahmi ( Bacopa monnieri ), given that Brahmi is a novel material for the synthesis of carbon dots and a medicinal plant. The nanoparticles’ size and morphology were analyzed using high-resolution transmission electron microscopy, field emission scanning electron microscopy, and dynamic light scattering techniques, while Raman spectroscopy, Fourier transform infrared spectroscopy), and X-ray diffraction spectroscopy were employed for sample characterization. Optical properties were studied using ultraviolet (UV) and fluorescence spectroscopy. The NCDs showed a high quantum yield of 15.7%, and demonstrated significant fluorescence quenching in the presence of Fe³⁺ and Ni²⁺ ions, with detection limits of 1.46 and 3.19 µmol·L ⁻¹ , respectively. This rapid, accurate method offers a promising solution for detecting heavy metals in water and could be expanded to real water samples and photocatalytic degradation of methylene blue dye under UV light.

Supramolecular containers have long been applied to regulate organic reactions with distinct selectivity, owing to their diverse functions such as the ability to pose a guest molecule(s) with a certain orientation and conformation. In this review, we try to illustrate how self-assembled coordination cages could achieve this goal. Two representative cage hosts, namely, self-assembled Pd(II)-ligand octahedral coordination cages ([Pd₆L₄]¹²⁺) and self-assembled Ga(III)-ligand tetrahedral coordination cages ([Ga₄L₆]¹²⁻) are selected as the pilot hosts that this mini review covers. Representative works in this area are presented here in brief.

(Triphenylphosphoranylidene)succinic anhydride, which is prepared from triphenylphosphine and maleic anhydride and is itself not reactive towards aryl aldehydes, is ring-opened with methanol to methyl (triphenylphosphoranylidene)succinate. In one pot, the newly formed phosphorane is reacted with aryl aldehydes to methyl aryl itaconates, which are subsequently hydrolyzed with aqueous sodium hydroxide to aryl itaconic acids. The biological activity of 12 aryl itaconic acids thus prepared against four gram-positive and four gram-negative bacterial strains has been studied.