Ultrasensitive and highly selective detection of formaldehyde an adenine-based biological metal-organic framework

• Published in: Materials chemistry frontiers 2021-03, Vol.5 (5), p.2416-2424
• Main Authors: Wei, Yu-Bai, Wang, Ming-Jie, Luo, Dong, Huang, Yong-Liang, Xie, Mo, Lu, Weigang, Shu, Xugang, Li, Dan
• Format: Article
• ISSN: 2052-1537
• DOI: 10.1039/d0qm01097a

Formaldehyde poses a carcinogenic risk to human beings, yet it would be difficult to accurately quantify by spectroscopic methods if other volatile organic compounds were present. Herein, we report a robust adenine-based BioMOF ( JNU-100 ) constructed through a mixed-ligand strategy with BPDC-(NH 2 ) 2 , an amine-functionalized dicarboxylate of intrinsically strong fluorescence, as the second ligand. JNU-100 exhibits an exceptional fluorescence "turn-on" exclusively for formaldehyde in aqueous solutions with a detection limit of 0.020 μM. In situ single-crystal X-ray diffraction studies reveal the hemiaminal formation on the Watson-Crick sites of adenines and the hemiaminal further stretching out to bridge over the neighboring BPDC-(NH 2 ) 2 through hydrogen bonding, which may suppress the nonradiative decay upon photoexcitation, resulting in restoration of the strong fluorescence of BPDC-(NH 2 ) 2 . 13 C solid-state NMR and isothermal titration calorimetry studies corroborate the hemiaminal formation on the Watson-Crick sites. Theoretical calculations confirm the fluorescence "turn-on" is originated from ligand-to-ligand charge transfer (LLCT) through the bridging hemiaminal. As a proof-of-concept, the rapid and visualizable response to formaldehyde is demonstrated by test strips. This work illustrates a successful design of MOF materials specifically for formaldehyde recognition without the interference of other volatile organic compounds by utilizing its reactivity on Watson-Crick sites and MOF compartmentalization. We demonstrate a successful design of an adenine-based BioMOF for highly sensitive formaldehyde recognition without the interference of other VOCs by utilizing its reactivity on Watson-Crick sites and MOF compartmentalization.