There is burgeoning interest among supramolecular chemists to develop novel molecular systems to detect biogenic amines and bio-thiols in aqueous and non-aqueous media due to their potential role in biological processes. Biogenic amines are biologically important targets because of their involvement in the energy metabolism of human biological systems and their requirement is met through food and nutrition. However, the increasing instances of serious health problems due to food toxicity have raised the quality of food nowadays. Biogenic amines have been frequently considered as the markers or primary quality parameters of foods like antioxidant properties, freshness and spoilage. For instance, these amines such as spermine, spermidine, cadavarine, etc. may originate during microbial decarboxylation of amino acids of fermented foods/beverages. These amines may also react with nitrite available in certain meat products and concomitantly produce carcinogenic nitrosamine compounds. On the other hand, it is also well established that biothiols, particularly, thiol amino acids, provide the basic characteristics to food including flavor, color and texture that determine its acceptability. For instance, the reduction of thiol groups produces hydrogen sulfide which reduces flavour as in rotten eggs and spoiled fish, and the presence of hydrogen sulfide in fish is indicative of spoilage. Thus, biogenic amines and bio-thiols have attracted the profound interest of researchers as analytical tools for their quantification. Much scientific and technological information is issued every year, where the establishment of precise interactions of biogenic amines and bio-thiols with other molecules is sought in aqueous and non-aqueous media. This review summarizes the optical chemosensors developed for the selective detection of biogenic amines and bio-thiols.

A convenient solvent-free method for the synthesis of benzothiazole, benzimidazole, and benzoxazole derivatives has been developed using recyclable ZnO-NPs via a ball-milling strategy. The method affords environmentally friendly reaction conditions that score high on the ecoscale with the low E-factor. The process is also highly efficient even on a multi-gram scale and provides easy product isolation.

Molecular recognition is an emerging field of Supramolecular Chemistry.

A solvent-free selective green synthesis of 1,2-disubstituted benzimidazoles was developed using a ball-milling technique. Recyclable ionic liquid-coated ZnO-nanoparticles (ZnO-NPs, catalyst 5) were employed as a catalyst, which produced high yields, turnover number and turnover frequency because of the synergetic catalytic properties of the ionic liquid and ZnO-NPs. The present method was successfully employed in the synthesis of various 1,2-disubstituted benzimidazole derivatives in excellent yields with high selectivity. The reaction could also be performed on a multi-gram scale with the same efficiency. A high eco-scale score and a low E-factor emphasize the ecofriendly nature of the present method.

A novel and easy-to-synthesize colorimetric and fluorescent chemosensor 1 was developed for the highly selective and sensitive recognition of Fe³⁺ and Cu²⁺. Receptor 1 showed a detectable color change from yellow to colorless with a blue-shift in the absorption spectra with Cu²⁺, while Fe³⁺ induced a color change from yellow to orange and a red-shift in the absorption spectra. In the emission study of 1, Fe³⁺ showed significant fluorescence enhancement with a slight red-shift while a selective fluorescence quenching was observed with Cu²⁺ over a wide range of tested metal ions. With Cu²⁺/Fe³⁺ as the chemical inputs, the ‘on–off’ emission profile of receptor 1 was developed as an IMPLICATION type logic gate at the molecular level.