  During the asymptoyic giant branch (AGB) phase, different elements are
dredge-up to the stellar surface depending on progenitor mass and metallicity.
When the mass loss increases at the end of the AGB, a circumstellar dust shell
is formed, where different (C-rich or O-rich) molecules and solid-state
compounds are formed. These are further processed in the transition phase
between AGB stars and planetary nebulae (PNe) to create more complex organic
molecules and inorganic solid-state compounds (e.g., polycyclic aromatic
hydrocarbons, fullerenes, and graphene precursors in C-rich environments and
oxides and crystalline silicates in O-rich ones). We present an observational
review of the different molecules and solid-state materials that are formed
from the AGB to the PN phases. We focus on the formation routes of complex
fullerene (and fullerene-based) molecules as well as on the level of dust
processing depending on metallicity.

Solar and Stellar Astrophysics;Astrophysics of Galaxies;Chemical Physics;Space Physics