In this review, our goal is comparison of advantageous and disadvantageous of MOFs about signal-transduction in different instrumental methods for detection of different categories of organic analytes.

Pore decoration of metal−organic frameworks (MOFs) with functional groups is a useful strategy to attain high selectivity toward specific analytes, especially in the presence of interfering molecules with similar structures and energy levels, through selective host−guest interactions. In this work, we applied a dihydrotetrazine-decorated MOF, TMU-34, with the formula [Zn(OBA)(H 2 DPT) 0.5 ] n •DMF, where H 2 OBA is 4,4′-oxybis-(benzoic acid) and H 2 DPT is 3,6-bis(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine, for the highly selective detection of phenolic NACs, especially TNP (94% quenching efficiency, detection limit 8.1 × 10 −6 M, K SV = 182663 mol L −1 ), in the presence of other substituted NACs especially −NH 2 -substituted NACs. Investigations reveal that the quenching mechanism is dominated by photoinduced MOF-to-TNP electron transfer through possible hydrogen-bonding interactions between the phenolic hydroxyl group of TNP and dihydrotetrazine functions of TMU-34. Despite extensive publications on the detection of TNP in the presence of other NACs, the significance of this work will be elucidated if attention is paid to the fact that TMU-34 is among the rare and highly selective MOF-based TNP sensors in the presence of −NH 2 -substituted NACs as the serious interferers.

Linker functionalization is a practical strategy to extend the applications of metal–organic frameworks (MOFs) in various fields. Here, this strategy is applied to synthesize a tetrazine-functionalized MOF [TMU-34(-2H), formulated [Zn(OBA) (DPT)0.5]·DMF; H2OBA and DPT are 4,4′-oxybis(benzoic acid) and 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine] for efficient photocatalytic synthesis of disulfides and benzimidazoles with maximum conversion after 90 and 120 min, respectively. The photocatalytic activity of TMU-34(-2H) originates from the electronic properties of tetrazine function, including absorption in the visible region and photogenerated redox activity. In the proposed mechanism, neutral tetrazine sites are excited upon visible-light irradiation. Then, photoexcited tetrazine sites accept one electron from the reactants leading to generation of tetrazine radical anions as electron mediator sites. Finally, the electrons transfer from the tetrazine radical anion sites to other substrates in the reaction. The results show that organic chromophores, such as tetrazine, are good candidates for extension of application of MOFs in visible-light photocatalysis.