Pyrazinyl-functionalized Zr(iv)-MOF for ultrasensitive detection of tyrosine/TNP and efficient CO2/N2 separation

Abstract

A pyrazinyl-functionalized Zr(IV)-based metal–organic framework (MOF), [Zr₆O₄(OH)₈(H₂O)₄(L)₂]·8DMF·10H₂O (HBU-18, H₄L = 2,3,5,6-tetrakis(4-carboxyphenyl)pyrazine), was successfully synthesized and characterized in this paper. HBU-18 shows a three dimensional (3D) coordination network with sqc topology, and the compound exhibits excellent chemical stability in either a strong acid or strong base. It is the first MOF-based fluorescent probe for selective detection of tyrosine (Tyr) from other natural amino acids (LOD = 94 nM, K_SV = 3.75 × 10⁵ M⁻¹). In addition, HBU-18 also exhibits an ultralow detection limit (LOD = 6.2 nM, K_SV = 2.46 × 10⁷ M⁻¹) for 2,4,6-trinitrophenol (TNP). The luminescence quenching mechanisms have been discussed in detail. Gas adsorption studies indicate that HBU-18 shows a CO₂ uptake of 49.17 cm³ g⁻¹ at 273 K (30.58 cm³ g⁻¹ at 298 K) with good selectivity for the CO₂/N₂ mixture under 1 atm. Therefore, HBU-18 can be a multifunctional material for fluorescence sensing and CO₂ adsorption.