Reactions of La(NO3)(3)center dot 6H(2)O with the polar, tritopic quaternized carboxylate ligands N-carboxymethy1-3,5-dicarboxylpyridinium bromide (H(3)CmdcpBr) and N-(4-carboxybenzyl)-3,5-dicarboxylpyridinium bromide (H(3)CbdcpBr) afford two water-stable metal-organic frameworks (MOPS) of 1 [La-4(CMdCp)(6)(H2O)(9)]}(n) (1, 3D) and {[La-2(Cbdcp)(3)(H2O)(10)]}(n) (2, 2D). MOFs 1 and 2 absorb the carboxyfluorescein (FAM)-tagged probe DNA (P-DNA) and quench the fluorescence of FAM via a photoinduced electron transfer (PET) process. The nonemissive P-DNA@MOF hybrids thus formed in turn function as sensing platforms to distinguish conservative linear, single-stranded RNA sequences of Sudan virus with high selectivity and low detection limits of 112 and 67 pM, respectively (at a signal-to-noise ratio of 3). These hybrids also exhibit high specificity and discriminate down to single-base mismatch RNA sequences.