Possible scenarios of the growth and evolution of the nanograins from a structural point of view, as sketched from the spectral variations of the IR bands. The possible role of UV irradiation in connecting different molecular assemblies and structures is underlined. This scenario is aimed at emphasizing the filiation between different nanostructures. In this scheme, the nomenclature at the top refers to all structures drawn below, for example, the polyaromatic dust comprises the soot particles, the PAH-like, the fullerenes and the mature AALHs photodesorbed species. The AALH and the soot particles are supposed to carry the class B and C AIBs. The class A could be emitted by PAH-like species and/or the mature AALH species. HACA refers to hydrogen abstraction and acetylene addition. The red squares on the primary particles images delimit the reminiscent soot nuclei.