Cyanotriacetylene or cyanohextriyne (HC₇N) was initially detected by Kroto et al. in 1978 toward Heiles cloud 2, more frequently known as TMC-1 (Taurus Molecular Cloud 1). The observations were performed with the 46m telescope at the Algonquin Radio Observatory in Ontario, Canada. The initial detection was quickly confirmed by Little et al., who observed HC₇N in TMC2, and by Winnewisser & Walmsley, who observed it in IRC+10216. Subsequent observations by Gardner et al., Rodriguez & Chaisson, Snell et al., and Cernicharo et al. extended the number of observed lines of HC₇N and added new sources, including Sgr B2 and Ll544.

Cyanotriacetylene is the third member of the HC_2n+1N family, which includes the cyanopolyynes (n≥2). Species in this family detected to date in space include: cyanoacetylene, HC₃N, cyanodiacetylene, HC₅N, cyanotriacetylene, HC₇N, cyanotetraacetylene, HC₉N, and cyanopentaacetylene, HC₁₁N. Three more members of the series have been characterized only in the lab: cyanohexaacetylene, HC₁₃N, cyanoheptaacetylene, HC₁₅N, and cyanooctaacetylene, HC₁₇N.