“…For pure polymer, absorption bands at 1785, 1718, 1351 and 719 cm -1 corresponded to asymmetric and symmetric C=O stretching, C-N stretching and imide five-ring deformation [25]. Besides, the signal at 1327 cm -1 was related to the asymmetric stretching of SO2 [35]. In the case of pure MOFs, NH2-MIL-53(Al) and NH2-MIL-101(Al) bands at 3504 and 3391 cm -1 and the shoulder at 1624 cm -1 corresponded to the asymmetric and symmetric amine stretching and the N-H scissoring vibration, thus confirming the presence of amino groups in the framework [20,24].…”