A lanthanide metal–organic framework containing a hydrazine group for highly sensitive luminescent sensing of formaldehyde gas

Abstract

The determination of formaldehyde (HCHO) concentration in human exhaled breath can be used as an effective means for the early diagnosis of lung cancer. Lanthanide metal–organic frameworks (LnMOFs) have shown great potential in formaldehyde fluorescence sensing, yet challenges persist in achieving high sensitivity and selectivity. In this work, we report new hydrazine-functionalized LnMOFs (Ln = Eu³⁺, Gd³⁺, Tb³⁺, H₂BDC–NH–NH₂ = 2-hydrazine-terephthalic acid), having an fcu topology for the sensitive and selective detection of formaldehyde gas. The ligands with hydrazine groups not only act as an “antenna effect” between the ligands and Eu³⁺ ions, but also act as formaldehyde recognition sites, enabling Eu-BDC–NH–NH₂ to be used for fluorescence enhanced sensing of formaldehyde gas in gaseous environments. Eu-BDC–NH–NH₂ thus exhibits low detection limit (41.7 ppb), high selectivity, and fast (3 minutes) formaldehyde gas response, showing great potential to be practically applied in the field of early diagnosis of lung cancer.