4,4-Di-fluoro-2,3;5,6-bis-(tetra-methylene)-4-bora-3a,4a-di-aza-s-indacene (LD540).

The title compound, C18H21BF2N2, is a lipophilic dye based on a BODIPY fluoro-phore backbone, which was developed for microscopic imaging of lipid droplets; the mol-ecule has a planar BODIPY core [dihedral angle between the pyrrole rings = 2.3 (3)°] and two tetra-methyl-ene substituents at the 2,3- and 5,6-positions in a half-chair conformation. One of the tetra-methyl-ene substituents is disordered over two two sets of sites with site occupancies of 0.5. In the crystal, pairs of C-H⋯F inter-actions link the mol-ecules into inversion dimers. Neighbouring dimers are linked by further C-H⋯F inter-actions, forming an infinite array. C-H⋯π and π-π [centroid-centroid distance = 4.360 (3) Å] inter-actions are observed between the BODIPY core and the tetra-methyl-ene substituents of neighbouring dimer pairs.