Multi-Responsive Luminescent Sensors Based on Two-Dimensional Lanthanide–Metal Organic Frameworks for Highly Selective and Sensitive Detection of Cr(III) and Cr(VI) Ions and Benzaldehyde

Abstract

Four new isostructural two-dimensional lanthanide­(III)–metal organic frameworks (MOFs), namely, [Ln­(L)­(HCOO)­(H₂O)]_<i>n</i> (Ln = Eu <b>1</b>, Gd <b>2</b>, Ho <b>3</b>, and Tb <b>4</b>, H₂L = 5-((2′-cyano-[1,1′-biphenyl]-4-yl)­methoxy)­isophthalic acid), with a uninodal {4⁴.6²}-<i>sql</i> topology have been successfully isolated. Compounds <b>1</b> and <b>4</b> exhibit excellent applications as luminescent sensors for sensing benzaldehyde in methanol and Cr³⁺, CrO₄^2–, and Cr₂O₇^2– in water with high sensitivity and selectivity based on luminescence quenching effects. Interestingly, <b>1</b> and <b>4</b> display excellent recyclable behaviors and can be recycled at least five times for sensing benzaldehyde, Cr­(III) and Cr­(VI) ions. These two compounds are the first multifunctional Ln–MOFs sensors for detecting benzaldehyde, Cr­(III) and Cr­(VI) ions, simultaneously. Therefore, these two materials may be excellent multifunctional recyclable luminescent sensors