donorinHacceptor

DonorinHacceptor is a term that appears in discussions of donor–acceptor chemistry to describe molecular motifs in which a donor unit is arranged in close relation to a hydrogen-bond–accepting site within the same molecule. The concept emphasizes the role of the hydrogen-bond acceptor as a structural and electronic partner that can influence charge transfer and proton dynamics, rather than functioning solely as an electron sink.

Structural features of donorinHacceptor motifs typically include a recognizable electron-donating fragment (for example, an amine, phenoxy, or arylamine unit) positioned near a hydrogen-bond acceptor group such as a carbonyl, imine, nitro, sulfone, or related heteroatom-containing moieties. These arrangements often rely on intramolecular hydrogen bonding to lock donor and acceptor units into a geometry favorable for electronic communication. Substituent tuning and backbone rigidity are common design elements used to optimize donor strength, acceptor basicity, and the stability of charge-transfer states.

Mechanistically, donorinHacceptor motifs are discussed in the context of processes that couple electron transfer with proton movement, such as proton-coupled electron transfer (PCET) or hydrogen-atom transfer (HAT). They may display distinctive spectroscopic signatures, solvatochromism, and potential enhancements in charge separation efficiency, with relevance to organic electronics, photochemistry, and catalysis.

Status and usage vary; the term is not a universally standardized descriptor but a descriptive label found in some literature to highlight the interplay between donor functionality and hydrogen-bond accepting environments within a single molecular framework. See also donor–acceptor systems, intramolecular hydrogen bonding, and PCET.