2021 was an outstanding year for the detection of new astromolecules, with over three dozen newly discovered species and several more tentatively identified. One of the first 2021 detections to be reported was 1-cyano-cyclopentadiene (c-C₅H₅CN), which was identified by McCarthy and co-workers toward TMC-1 using the 100m Green Bank Telescope.

As Michael McCarthy and Brett McGuire noted in a subsequent article featured in the Journal of Physical Chemistry A, the recent discoveries of 1-cyano-cyclopentadiene and benzonitrile are marking the beginning of a new era of detections involving organic compounds with one or more rings containing 5 or 6 carbon atoms. Identifications of 2-cyano-cyclopentadiene, two cyanonaphthalene isomers, cyclopentadiene, indene (see also here), o-benzyne, two ethynyl-cyclopentadiene isomers, and the tentative detection of ethynyl-benzene followed just in 2021 so far.