Quinoxalines, also known as benzopyrazines, are heterocyclic compounds containing a ring complex consisting of a benzene ring and a pyrazine ring. It has isomerism with other naphthalene compounds such as quinazoline, phthalazine, cinnamine, etc. Fusion N-heterocyclic compounds are widely used as valuable entities for the expansion of important pharmacological agents and are considered to be an advantageous scaffold material. Among the numerous fused N-heterocyclic compounds, cinnoline, quinoxaline and quinazoline are important pharmacological agents. In medicinal chemistry, these N-heterocyclic compounds have a wide range of biological properties and can be used as synthetic intermediates, potential drug candidates and chemical probes.
The two N atoms in Benzothiadiazole could possibly form intermolecular hydrogen bonding, leading to a more planar backbone. Benzothiadiazole is a strong electron-accepting molecular fragment. By fusing it with thiazole donor-acceptor dyes, near-infrared fluorescence was created. The benzothiadiazole ring is a useful n-type building block for designing electron-transport materials for organic and polymer light-emitting diodes (LEDs). Arene- and heteroarene-fused thiadiazoles have also found use in the design of low-band-gap materials for the construction of organic field-effect transmitters (OFETs), as stable organic radicals, and as one or two photon-absorbing materials for the design of nonlinear near-infrared (NIR) dyes. Benzothiadiazoles acting as the electron-accepting cores have been incorporated into dendrimer-type light-harvesting materials.