Multiresponsive Luminescent Sensitivities of a 3D Cd-CP with Visual Turn-on and Ratiometric Sensing toward Al³⁺ and Cr³⁺ as Well as Turn-off Sensing toward Fe³⁺

Abstract

By using the reduced Schiff base tricarboxylate ligand H 3 cip, one novel 3D Cd-based coordination polymer (Cd-CP) with the formula [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (H 3 cip = 5-(3-carboxybenzylamino)isophthalic acid, bpea = 1,2-bis(4-pyridyl)ethane) has been solvothermally synthesized. The prepared Cd-CP possesses a 4-connected CdSO 4 net based on dinuclear {Cd 2 } units. Luminescence measurements revealed that the complex exhibited ratiometric turn-on luminescence responses toward Al 3+ and Cr 3+ with a significant color change, which could be easily distinguished by the naked eye under ultraviolet light. Cd-CP can also respond to Fe 3+ through a turn-off mechanism. Interestingly, the luminescence quenched by Fe 3+ @Cd-CP can be recovered and increased significantly by adding some competitive Al 3+ , while Cr 3+ can only marginally increase the luminescence intensity of Fe 3+ @Cd-CP. Moreover, the detection of the three aforementioned metal ions can be realized by using Cd-CP-coated test papers, extending the potential application regions of the reported material to point-of-care tests and environmental field studies.

Recent advances in process engineering and upcoming applications of metal–organic frameworks

“… MOF compounds Sensing targets LOD Number of recycles Ref a. Metal ion sensors NH 2 -MIL-125(Ti) Pb 2+ 0.70 × 10 −2 nM 5 [405] [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (Cd-CP) Fe 3+ 3.24 µM 5 [406] [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (Cd-CP) Al 3+ 1.31 µM 5 [406] [Cd(Hcip)(bpea) 0.5 (H 2 O)] n (Cd-CP) Cr 3+ 1.84 µM 5 [406] MOF NU-902 Cd 2+ 0.3 ppb – [407] MOF NU-902 PVC membrane Cd 2+ – – [407] CAU-10-V-H Pd 2+ 110 nM 5 [408] MIL-53(Al)–NH2-MPA Fe 3+ 0.36 µM – [416] [[Zn(4,4′-AP)(5-AIA)]. (DMF)0.5] n Hg 2+ 0.01 nM – [409] b. Anion sensors TMU-41 Cr 2 O 7 2− 0.02 µM 4 [410] TMU-41 CrO 4 2− 0.03 µM 4 [410] …”

“…Thus, research has been conducted into the development of selective and sensitive sensor probes for their detection. A Cd-based coordination polymer ([Cd(Hcip)(bpea) 0.5 ·(H 2 O)] n , denoted as Cd-CP) was prepared recently for sensing these metal cations [406] . The researchers analyzed the fluorescence signals at various metal ion concentrations, and found that the Cd-CP MOF shows detections limits of 1.31, 1.84, and 3.24 µM for Al 3+ , Cr 3+ , and Fe 3+ , respectively.…”

State of the art methods and challenges of luminescent metal–organic frameworks for antibiotic detection

“…30,31 Luminescent MOFs (LMOFs) are a major category of MOFs, which are considered to be potential candidates as sensor materials to detect multiple substances, including heavy metals, 32 explosives, 33 and toxicants. 34 Compared with other luminescence materials, LMOFs have numerous excellent advantages, including multiple light sources, large Stokes shift, high luminance, stability, and host-guest interaction. The porous nature of LMOFs can enrich the guest analyte in LMOFs by capturing the trace analyte to enhance the sensing performance.…”

Rhodamine‐Based Fluorescence ‘Turn‐On’ Chemosensor: Detection of Fe3+Ion in Aqueous Medium and MCF‐7 Live Cells

“…[11] Being paramagnetic in nature, Fe 3 + detection by fluorescence probes results in quenching of emission intensity which may limit the detection. [12][13][14] Different types of sensors have been developed for detection of Fe 3 + ion that include optical fiber, [15,16] colorimetric, [17][18][19][20][21] potentiometric, [22,23] MOF-based, [24][25][26][27] electrochemical, [28][29][30] polymer-based [31,32] and fluorescent sensors. [33][34][35][36][37] Many traditional techniques were also used to detect Fe 3 + ions, such as atomic absorption spectroscopy (AAS), [38] inductively coupled plasma -mass spectroscopy (ICP-MS), [39] spectrophotometry, [40] voltammetry, [41] extraction spectrophotometry (ES) and resonance scattering spectrometry.…”