(E)-7-(Pyren-1-yl)hept-6-enoic acid.

The title compound, C(23)H(20)O(2), is a precursor of a pyrene-based supra-molecular element for non-covalent attachment to a carbon nanotube. The asymmetric unit contains three independent mol-ecules. The carb-oxy-lic acid group in each of these mol-ecules serves as an inter-molecular hydrogen-bond donor and acceptor, generating the commonly observed double O-H⋯O hydrogen-bond motif in an eight-membered ring. Weaker C-H⋯O, π-π [centroid-centroid distance = 3.968 (4) Å] and C-H⋯π inter-actions are also found in the crystal structure.