Post-synthetic Modification of a Two-Dimensional Metal–Organic Framework via Photodimerization Enables Highly Selective Luminescent Sensing of Aluminum(III)

Abstract

Reaction of Cd­(NO3)2·4H2O with 5-fluoro-1,3-bis­[2-(4-pyridyl)­ethenyl]­benzene (5-F-1,3-bpeb) and 1,3-benzene­dicarboxylic acid (1,3-H2­BDC) under the solvothermal conditions gave rise to a two-dimensional metal–organic framework (MOF) [{Cd2­(5-F-1,3-bpeb)2­(1,3-BDC)2}·0.5DMF·2H2O] n (1). Compound 1 was postmodified by a photodimerization reaction between 5-F-1,3-bpeb ligands to yield [{Cd2­(syn-dftpmcp)­(1,3-BDC)2}·0.5DMF·H2O] n (syn-dftpmcp = syn-3,4,­12,13-tetrakis­(4-pyridyl)-8,17-bisfluoro-1,2,­9,10-diethano­[2.2]­metacyclophane) (2). Compounds 1 and 2 have 2D networks built from linking one-dimensional [Cd2­(1,3-BDC)2] n chains via 5-F-1,3-bpeb or syn-dftpmcp bridges. After such a post-synthetic modification, compound 2, relative to 1, can probe Al3+ by using a luminescent quenching approach with much higher selectivity and sensitivity.

Reversible on-off switching of spin-crossover behavior via photochemical [2+2] cycloaddition reaction

“…Besides the unidirectional dimerization reaction, the attempt on reverse cleavage of cyclobutane ring in 2 was further explored. According to some recent work, higher wavelength light irradiation or heating of the cyclobutane product could be used to achieve the inversion process [7,[13][14][15][16][17]. However, after 2 days irradiation of the polycrystalline samples 2 by a 50 W low-pressure Hg lamp (λ= 254 nm), the PXRD patterns (Figure S10) and IR spectra (Figure S11) of the irradiation sample show no apparent change in comparison to the initial data, indicating an inert reactivity.…”

“…However, in most cases, only the unidirectional photochemical [2+2] cycloaddition reaction is reported. The reversible cleavage of the cyclobutane ring to the olefins [7,[13][14][15][16][17], which is necessary for potential applications in photoswitching, optical recording, and sensing, has rarely been explored.…”

Two‐dimensional MOFs: Design & Synthesis and Applications

“…Therefore, MOF2 has a higher selectivity than MOF1 in the detection of Al 3+ (Figure 9). [102] Li's team has synthesized three new MOF materials, among which the first MOF1 has 2D topology, and the second and third MOF2 and MOF3 have three‐dimensional topology [103] . MOF1‐2 shows strong luminescence and high stability in water.…”

Recent Advances in Nanocomposite Luminescent Metal-Organic Framework Sensors for Detecting Metal Ions

“…The prepared MOFs and its photopolymerized derivative were found to be selective for the detection of Al 3+ ions through a luminescence quenching approach with a detection limit of 183 ppb. [149] Han et al have reported that [Cd 2 (OBA) 2 (BPTP)(H 2 O)] with BPTP is a V-shaped thienylpyridyl ligand and OBA is 4,4′-oxidibenzoic acid, which showed a dual-responsive luminescent probe for Fe 3+ and Al 3+ ions in DMF suspension. [150]…”