Carbon Dots (CDs) can be defined as carbon nanoparticles with a size from 1-10 nm, with absorption and photoluminescence activity in the UV-vis range. CDs can have crystalline or amorphous structure, this wide range of structures opens up the possibility to design different CDs. The luminescence properties of CDs change not only according to the type of structure, but also according to the type of chemical group that covers the surface, such as: amino groups, carboxylic or ester groups and others. In this work we synthesized CDs with a bottom up approach and we obtained two different CDs graphitic and diamond like, they were purified with Size Exclusion Chromatography (SEC) in order to obtain fairly pure CDs for sensing tests. They have been characterized to study the optical properties with spectroscopic techniques like absorption and fluorescence spectroscopic and with Raman spectroscopic and Atomic Force Microscopy (AFM) we studied the different structure and the morphology of the CDs. Finally with fluorescence we evaluated the interactions between CDs and pollutants.