A sensor for formaldehyde detection: luminescent metal–organic framework [Zn2(H2L)(2,2′-bpy)2(H2O)]n

Abstract

Density functional theory and time-dependent density functional theory methods have been used to investigate the hydrogen bonding between the Metal–organic framework [Zn₂(H₂L)(2,2′-bpy)₂(H₂O)]_n and formaldehyde in the electronically excited state. The calculated geometric configuration, ¹H NMR chemical shift and IR spectra of the hydrogen-bonded complex demonstrated that the hydrogen bond was strengthened in the excited state S₁. The strengthening of the hydrogen bond in the S₁ state would lead to a luminescence decreasing phenomenon of [Zn₂(H₂L)(2,2′-bpy)₂(H₂O)]_n, and the fluorescent rate constant of [Zn₂(H₂L)(2,2′-bpy)₂(H₂O)]_n was decreased when encapsulating formaldehyde into it. Taken together, these results indicated that [Zn₂(H₂L)(2,2′-bpy)₂(H₂O)]_n could be used for the detection of formaldehyde.