Thiophene is a five-membered heterocyclic compound containing a sulfur heteroatom with the molecular formula C4H4S. Thiophene is aromatic and is very similar to benzene; electrophilic substitution reaction is easier than benzene, and it is mainly substituted at the 2-position. Thiophene ring system has certain stability to oxidant.
Oxazoles are heterocyclic aromatic compounds containing one oxygen atom and one nitrogen atom, separated by a carbon atom. The presence of two heteroatoms (oxygen and nitrogen) provides possible interactions (hydrogen, hydrophobic, van der Waals or dipole bonds) with a wide range of receptors and enzymes. Oxazole rings are valuable heterocyclic scaffolds for the design of novel therapeutics with anticancer, antiviral, antibacterial, anti-inflammatory, neuroprotective, antidiabetic, and antidepressant properties due to their wide range of targets and biological activities.
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.