Similarly to graphene, carbon nanotubes are materials made of pure carbon in its sp 2 form. Their extended conjugated π-network provides them with amazing quantum optoelectronic properties. Frustratingly, it also brings drawbacks: The π-π stacking interaction makes as-produced tubes bundle together, blurring out all their quantum properties. Functionalization aims at modifying and protecting the tubes while hindering π-π stacking. Several functionalization strategies have been developed to

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... mvent this limitation and for nanotubes applications to thrive. In this review, we summarize different approaches established so far, emphasizing the balance between functionalization efficacy and preservation of the tubes' properties. Major attention will be devoted to a functionalization strategy overcoming the covalent-noncovalent dichotomy and to the implementation of two advanced functionalization schemes: a) conjugation with molecular switches, to yield hybrid nanosystems with chemo-physical properties that can be tuned in a controlled and reversible way and b) plasmonic nanosystems, whose ability to concentrate and enhance the electromagnetic fields can be taken advantage of for enhancing the optical response of the tubes.