Analysis of diffuse reflectance measurements for BDP-TFP-COF powder samples with the Kubelka-Munk function displayed a broad absorption in the whole visible region with a maximum absorption at 575 nm (Figure ). From the Tauc plot, a direct optical bandgap of 1.82 eV was estimated (Figure ). According to these combined analytical data, BDP-TFP-COF was established as a highly stable and porous framework with intriguing optical properties originated from the precise ordering of BODIPY units within the crystalline lattice.