X-ray absorption measurements of BTD-FL, BTD-FLBr, and BTD-HeBr are performed to investigate their X-ray absorption ability (Fig. ). As expected, the resonant absorption edges largely increase from BTD-FL to BTD-FLBr and BTD-HeBr due to the introduction of heavy atoms. The absorption coefficients of BTD-HeBr (Zmax = 35, Kα = 13.5 keV) was slightly higher than that of BTD-FLBr, which indicates that the through-space bromine atoms exhibit better X-ray photon absorption ability.