Giant Isotope Effect in Metal–Organic Frameworks Boosts Unprecedented Photo‐ and Radio‐Luminescence Enhancement

ABSTRACT Isotope effect (IE) has emerged as a powerful strategy for tailoring the photophysical properties of luminescent systems, yet its application in solid materials remains limited. Herein, we presented a simple and general in situ deuteration strategy to synthesize a series of deuterated metal–organic frameworks (MOFs) with enhanced emission performance. One resulting MOF (EuBTC‐D) exhibits an IE‐triggered comprehensive luminescence enhancement (4.15‐fold longer lifetime and 3.49‐fold higher quantum yield) that surpasses all reported solid‐state deuterated materials. The giant isotope effect is attributed to the drastic suppression of non‐radiative decay in EuBTC‐D, where deuteration effectively freezes the molecule thermal motions of the water‐rich framework and stabilizes the long‐lived triplet excitons. Furthermore, the scope of IE is further extended to radioluminescence, yielding upgraded X‐ray detection sensitivity and imaging resolution. This work establishes isotopic engineering as a versatile and powerful Isotope effect, Metal–organic framework, Photoluminescence, Radioluminescencetool for developing advanced luminescent MOFs and scintillating materials.