Fast photoluminescence and scintillation with a Stokes shift larger than 1 eV is achieved in hetero-ligand metal-organic framework (MOF) crystals comprising inorganic linking nodes and fluorescent conjugated ligands. By finely engineering the MOF composition with the use of ligands with strictly complementary emission and absorption properties and highly delocalized molecular electronic orbitals, we boost the the singlet excitons diffusion through the ligand framework fully exploiting both Forster and Dexter energy transfers mechanisms. This allows the sensitization of energy acceptor ligand fluorescence through ultrafast non-radiative energy transfer with a rate up to the THz range. This efficient antenna effect activates instantenlusly the MOF scintillation with a Stokes shift as large as 1.3 eV in the blue spectral range, matching the highest sensitivity spectral window of the best photodetector available. This was obtained using a minimal doping level of the energy acceptor species, with a consequent elimination of emission re-absorption that enable a 500% increment of the MOFs scintillation efficiency and to detect the radioactive krypton isotope 85Kr from the gas phase with an improved sensitivity with respect to the reference material.