The origin of chemical complexity from cm to mm: in the heart of young forming planetary system

The earliest phases of planetary system formation are marked by a fascinating and intricate chemistry, with a high abundance of prebiotic molecules detected in protostellar environments. This chemical complexity serves as a crucial diagnostic tool to understand the underlying physical processes shaping these nascent systems, and to probe the chemical evolution from prestellar core to more evolved disks. Indeed, part of the chemical processing happening during the prestellar and protostellar phase may affect later stages of evolution. For example, the observed diversity in the large variety of exoplanets detected so far, can be the result of a diversity already present at the early stages of their formation. One of the striking results of the past years is the chemical diversity revealed in Sun-like protostars. Indeed, from a chemical point of view protostars differs from each other: some of them show millimetric molecular spectra rich in interstellar organic complex molecules (the so called hot corinos), and some others are enriched of unsaturated small carbon chains (the so called WCCC sources). The origin of this diversity is still unclear, as well as its impact on the chemical composition of future forming planets. In this talk, I will review the observational efforts carried out in the past years to chemically characterize the inner regions of Solar-system analogs. I will summarize the current understanding of the molecular complexity from large prestellar cores to compact protoplanetary disks, with emphasis on the origin of the molecular differentiation observed in protostars.