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Abstract
The development of responsive materials for monitoring atmospheric toxic emissions is a growing area of interest. Luminescent metal–organic frameworks, particularly those based on lanthanides (LnMOFs), have emerged as promising candidates due to their sharp emission bands, long luminescence lifetimes, and structural versatility. Despite their potential, the integration of LnMOFs into robust solid-state sensing platforms remains limited. In this study, we report the synthesis of two isostructural LnMOFs—[Tb₂(AATA)₃(DMF)₄] and [Eu₂(AATA)₃(DMF)₄]—based on the antenna-type ligand 2,5-bis(acetylamido)terephthalic acid, which promotes strong lanthanide emission and stable 2D frameworks. The MOFs were successfully embedded into polydimethylsiloxane (PDMS) to produce composite films retaining their luminescent properties in the solid state. We further present a conceptual bilayer configuration with one film acting as a stable internal reference, and the other serving as the analyte-responsive layer. This bilayer design enables ratiometric luminescence detection, thereby enhancing the accuracy and reliability of the measurements. As a proof-of-concept, we demonstrate that the bilayer films exhibit measurable luminescence changes in presence of two major atmospheric pollutants, NO₂ and SO₂. This result sets a foundational approach for developing more accurate and self-referencing luminescent materials.
Supplementary materials
Title
SI
Description
1) Experimental section
2) Synthesis of 2,5-bis-acetylamido-terephtalic acid, 1 and 2
3) FTIR of 1 and 2
4) TGA of 1 and 2
5) SCXRD of 1, 2 and 3
6) Normalized and PL spectra for 1 and 2
7) Normalized and PL spectra for 1@PDMS and 2@PDMS
8) PL Lifetime of 1 and 2 at room temperature
9) Fourier transform infrared spectra for 1@PDMS and 2@PDMS
10) Ratiometric sensing measurements
11) Sensing at lower pollutant concentrations, detection and quantification limits
12) 1@PDMS and 2@PDMS luminescence ageing
13) PL intensity behavior of the bilayer
14) Luminescence measurements at 73 K of compound 3
15) Jablonski diagram and energy states data
17) N2 adsorption and BET surface analysis for compounds 1 and 2
18) Comparative study of different bilayer systems used before
19) SO2 and NO2 distribution inside the cavities of calculated via DFT
20) Ab initio calculation details
21) References
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