Luminescence-based methods are highly attractive for chemical sensing and offer several potential advantages such as a low limit of detection, high sensitivity, and fast response. Particularly desirable, yet still challenging to achieve, are “turn-on” sensors that luminesce only in the presence of analyte and are non-emissive in the absence of analyte. The metal-centered photoluminescence (PL) of lanthanide (Ln3+) compounds, such as metal-organic frameworks (MOFs), complexes, and simple salts, offers unique opportunities for chemical sensing of toxic molecules, chemical warfare agents, volatile organic compounds and biologically relevant compounds, etc. in both solid-state and solution. Gossypol (Gsp), a natural toxin concentrated in cottonseeds, poses great risks to the safe consumption of cottonseed products which are used extensively throughout the food industry. 1-hydroxypyrene (OH-Py) is a biomarker for polyaromatic carcinogens. Sensitive and selective turn-on detection strategies for Gsp and OH-Py are highly desirable and significantly important. We first demonstrate that the Yb3+ photoluminescence of a Yb3+ MOF, Yb-NH2-TPDC, can be employed to selectively detect Gsp with a limit of detection of 25 μg/mL via a “turn-on” response from a completely non-emissive state in the absence of Gsp. Hydroxy-functionalized Yb-OH-BPDC was employed for the selective turn-on detection of OH-Py. The repeatability and durability of turn-on sensing in the presence of Gsp and OH-Py were monitored. We further identified that the “turn-on” of Yb-MOF photoluminescence was due to the “antenna effect” of Gsp and OH-Py, as evidenced by spectroscopic studies and supported by computational analysis. Leveraging this sensing mechanism, we also demonstrate facile, highly sensitive, fast-response detection of Gsp and OH-PY using Yb-salt. Overall, we show for the first time that lanthanide-based materials are promising luminescent turn-on sensors for Gsp and OH-Py detection. We envision that the reported sensing approach will be applicable to the detection of a wide variety of aromatic molecules using Ln compounds including MOFs, complexes, and salts.

Luminescent “turn-on” detection of toxic molecules using lanthanide-based metal-organic frameworks

ACS Spring Meeting 2021

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