Multicomponent reactions (MCRs) are considered a green strategy by generating diversity of scaffolds from less synthetic effort and safe conditions. This work present the synthesis of dimethyl 8-(tert-butylamino)-4-oxo-4,6-dihydropyrimido[2,1-b][1,3]thiazine-6,7-dicarboxylate in low to moderate yields 33–74 % from the prepared 2-amino-4H-1,3-thiazin-4-one derivatives containing both an acidic proton and a suitable nucleophile with alkyl isocyanides and DMAD/DEtAD. The work portrays facile method under green chemical production processes using green solvents such as acetone, ethanol, isopropanol, and 2-methyl-tetrahydrofuran. This chapter shows the flexibility of zwitterion adduct from the reaction of alkyl isocyanide and DMAD. The zwitterion adduct is trapped by 2-amino-4H-1,3-thiazin-4-one derivatives and forms fused [6-6] heterocyclic compounds. The preparation of starting material thiazine was carried out at different condition from 0 °C temperatures to reflux, while the synthesis of novel dimethyl 8-(tert-butylamino)-4-oxo-4,6-dihydropyrimido[2,1-b][1,3]thiazine-6,7-dicarboxylates was done at room temperature without the use of catalyst.

Heavy metal contamination in environmental matrices, such as water, wastewater, and soils, poses serious ecological and public health risks, necessitating efficient and sustainable treatment strategies. Advanced membrane technologies for the selective separation and removal of heavy metals, such as nanofiltration, reverse osmosis, forward osmosis, ultrafiltration using functionalized materials, liquid membranes, and nanocomposite membranes, are critically reviewed in this chapter. The key findings demonstrate that functionalized and nanocomposite membranes, especially when incorporated into hybrid membrane adsorption or electrochemical systems, yield high rejection efficiency (> 90% in many systems), higher selectivity, and improved anti-fouling performance. However, challenges related to energy consumption, membrane fouling, and concentrate management remain barriers to large-scale implementation. A bibliometric analysis underlines the need for scalable, energy-efficient, and circular economy-aligned systems for environmental remediation, further highlighting the increased interest in nanomaterial-enhanced and sustainability-oriented membrane solutions in research worldwide. The chapter ends with a summary of future directions for membrane solutions for heavy metal remediation across various environmental matrices that are scalable, energy-efficient, and linked with the circular economy.

The structures and content variations of biomolecules can be seen using fluorophores and fluorophores-based probes or labels, which have advanced significantly in the wide spectrum of areas of biomedicine. Studying biological systems requires the use of organic fluorophores, which are made possible by modern microscope imaging techniques. The visualisation of biomolecule synthesis, conformational changes, and interactions in biological systems through fluorescence imaging, is one of the most potent bioanalytical methods. Mostly fluorescence imaging methods for biomedical studies primarily use fluorescent dyes and nanoparticles due to the insufficient fluorescence of biological device. Fluorophores and fluorophores-based probes or labels, which have made major advancements in a wide range of biomedical fields, can be used to observe the structures and content fluctuations of biomolecules. Organic-based fluorescent compounds have been widely used in biomedicine as raw materials for production of flexible imaging and sensing devices. Modern microscope imaging techniques enable the use of organic fluorophores, which are necessary for studying biological systems. Red/near-infrared emitting fluorophores have recently attracted a lot of scientific attention because they enable bioimaging applications with reduced autofluorescence interference and light scattering, two key hurdles to deep-tissue imaging, as well as reduced photodamage and photobleaching. Herein, we looked at the effectiveness and limitations of the current techniques for transforming significant organic fluorophores’ cores into derivatives with extended wavelengths of emission. Together, we discuss key sensing properties and typical applications of these fluorophores to produce molecular probes for biological analytes. Finally, we listed certain crucial elements to take into account when synthesising new fluorophores.