Abstract
Low-cost, high-performance luminescent probes with wide application potential have been actively pursued. Conventional luminescent probes, which rely on single or dual emissions responsive to analyte molecules, demonstrate limited sensitivity and selectivity because the single emissions can be easily affected by many non-analyte factors, while the dual emissions can only offer single-ratiometric luminescent sensing. Here we report a white-light-emitting trichromatic MOF composite (W2) as the first multidimensional ratiometric luminescent probe. It is facilely synthesized by simultaneously incorporating red- and green-emitting iridium and ruthenium complex cations as encapsulated luminescent modules (ELMs) into a porous blue-emitting MOF via ion exchange. Specific volatile organic solvents (VOSs) can cause VOS-dependent changes to the MOF-to-ELM energy transfer efficiencies in W2, while nitroaromatic (NAC) vapors intriguingly and unprecedentedly quench the three emissions at different rates, both of which enable visible luminescent sensing. Each VOS can be correlated to a unique combination of the two MOF-to-ELM ratios of emission-peak heights, enabling a two-dimensional (2D) code recognition. Furthermore, the time-dependent evolution of the two ratios upon exposure to selective NAC vapors can be mapped out, achieving the first 3D code recognition. Both the synthetic and sensing strategies can be further implemented to develop low-cost and effective luminescent probes.
Highlights
Luminescent sensing has been proven viable in detecting volatile organic solvents (VOSs), harmful chemicals such as explosive nitroaromatics (NACs) and heavy metal ions.[1,2]
Among them, the vast majority output the luminescence intensity evolution of single emissions as their signals when analyte molecules interact with metal–organic frameworks (MOFs) to turn their emissions on or off
From the emission spectra of its suspensions in different VOSs (Fig. 3A), a unique combination of both IMOF/I[Ir]+ and IMOF/I[Ru]2+ are derived for each VOS. Such VOS-dependent ratiometric luminescence is caused by the changes of the MOFto-encapsulated luminescent modules (ELMs) energy transfer efficiencies and/or the energy allocation between [Ir]+ and [Ru]2+ when different VOS molecules are included within the MOF channels/cages.[13]
Summary
Luminescent sensing has been proven viable in detecting volatile organic solvents (VOSs), harmful chemicals such as explosive nitroaromatics (NACs) and heavy metal ions.[1,2] Though on-site and selective sensing can sometimes be achieved even accompanied by visible luminescence changes, luminescent sensing still needs signi cant improvement from the perspectives of selectivity, sensitivity, and cost, before wider application.[3]. We present a novel white-light-emitting (WLE) MOF composite (W2, CIE coordinate: (0.33, 0.34)) using its three tunable red-green-blue emissions for multidimensional ratiometric luminescent sensing.
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