Metal–organic framework-based sensors for the detection of heavy metal ions in water

Guo-Zhu Liu , Zheng-Dong Liang , Zhu-Jun Long , Jie-Wei Liu , Huan-Ying Li * and Zong-Wen Mo *
School of Environmental and Chemical Engineering, Wuyi University, Jiangmen, Guangdong 529000, PR China. E-mail: wyuchemmzw@126.com

First published on 19th June 2025

---

---

Guo-Zhu Liu

Guo-Zhu Liu is currently pursuing an M.S. degree in Environmental and Chemical Engineering at Wuyi University under the supervision of Associate Prof. Zong-Wen Mo. His current research interests focus on the design and preparation of functional porous coordination polymers for gas separation.

Zong-Wen Mo

Zong-Wen Mo received his Ph.D. degree in 2019 under the supervision of Prof. Jie-Peng Zhang at Sun Yat-sen University and is currently an associate professor at Wuyi University. His current research interests focus on flexibility, photoluminescence and adsorption of porous coordination polymers.

---

Introduction

The problem of global water pollution has increased significantly, posing a serious threat to human health and the environment.¹ Among pollutants, the pollution of heavy metal ions (such as Pb²⁺, Fe³⁺, Hg²⁺, Cr³⁺, etc.) is particularly prominent.² The traditional detection methods, including atomic fluorescence spectrometry and atomic absorption spectrometry, offer advantages such as high sensitivity, low detection limits, and good selectivity.³ However, their reliance on costly instrumentation, intricate synthetic protocols, and prolonged preparation cycles significantly restricts their large-scale deployment. Consequently, the development of effective methods for the rapid, inexpensive, and user-friendly detection of heavy metal ions has become critical.⁴

As a novel class of porous materials, metal–organic frameworks (MOFs), also known as porous coordination polymers (PCPs), are well known for their high designability, large specific surface area, and tunable porous structures, making them suitable for numerous applications, including gas storage,⁵ selective adsorption/separation,⁶ catalysis⁷ and sensing.⁸ Compared to conventional porous materials, MOFs exhibit unique host–guest interactions that can be converted into detectable signals, including changes in fluorescence intensity/wavelength,⁹ electrochemical responses,¹⁰ and visible color variations,¹¹ enabling the detection of heavy metal ions (Fig. 1).¹² Furthermore, the adjustable pore size/shape and flexibility of MOFs can precisely regulate the diffusion rate of heavy metal ions into pores, leading to quantifiable signal variations. To date, various MOF-based sensors have been developed for detecting heavy metal ions, utilizing mechanisms such as fluorescence quenching/enhancement, electrochemical sensing, and colorimetric detection (Scheme 1). In this review, we summarize recent progress in MOF-based detection of heavy metal ions and discuss future directions in the application of MOF sensors (Table 1). At the same time, we aim to resolve the challenges of MOF-based sensors, clarify their practical application potential for heavy metal ion detection in water, and establish a theoretical foundation for developing more efficient and sensitive sensors.

---

MOF-based fluorescence quenching sensors

As one of the most widely used techniques for detecting heavy metal ions, fluorescence quenching sensors produce measurable signals through monitoring changes in the fluorescence intensity. The fluorescence quenching mechanisms can be classified into four categories: (1) interaction between functional organic ligands and metal ions,¹³ (2) electron or energy-transfer processes,¹⁴ (3) competitive energy absorption,¹⁵ and (4) the synergistic effects of the aforementioned mechanisms.¹⁶

The most prevalent mechanism primarily involves interactions between the metal ions and uncoordinated atoms or functional groups on the organic ligands.¹⁷ For example, a two-dimensional MOF, [Tb(DOP)(H₂O)₅] (H₃DOP = 5-hydroxyisophthalic acid), exhibits significant green fluorescence and enables ultrasensitive detection of Pb²⁺ ions in aqueous solution. The performance can be attributed to the weak coordination interaction between Lewis basic sites (oxygen atoms from the phenolic group) within the MOF and Pb²⁺ ions, which significantly perturbs the energy transfer efficiency. Notably, this represents the first reported luminescent MOF sensor for detecting Pb²⁺ ions at trace concentrations, with a limit of detection (LOD) of 10⁻⁷ M.¹⁸ Furthermore, triazine-based ligands and their derivatives have shown great potential in luminescence responsive applications due to their unique electronic properties.¹⁹ A new triazine and amine functional MOF, [Me₂NH₂]₅[La₃(μ-O)(TATAT)₂] (La-TATAT, H₆TATAT = 5,5′,5′′-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)triisophthalic acid), exhibits sensitive fluorescence quenching behavior toward Cu²⁺ or Fe³⁺ ions. This quenching effect arises from weak interactions between the Cu²⁺/Fe³⁺ ions and uncoordinated N atoms within the framework. Notably, this MOF can selectively detect Cu²⁺ and Fe³⁺ even in the presence of other interfering metal ions, with the LODs of 1.97 × 10⁻⁵ M and 5.08 × 10⁻⁵ M, respectively (Fig. 2).²⁰

Alternatively, fluorescence quenching can also occur based on the electron or energy-transfer mechanism between ligands and metal ions, enabling effective detection.²¹ For example, a similar functional MOF, [Al(OH)(ABDC)] (H₂ABDC = 2-amino-1,4-benzenedicarboxylic acid), can detect Hg²⁺ based on strong coordination between the –NH₂ groups/nitrogen centers and Hg²⁺. This interaction modulates the ligand-to-metal charge transfer (LMCT) process, leading to detectable changes in the optical response. The system demonstrates excellent sensing performance, demonstrating a broad linear range (1–17.3 μM), low LOD (0.15 μM), high selectivity for Hg²⁺, wide pH adaptation (4.0–10.0) and strong anti-interference capability.²² Additionally, the luminescent MOF, [Mg₂(APDA)₂(H₂O)₃] (Mg-APDA, H₂APDA = 4,4′-(4-aminopyridine-3,5-diyl)dibenzoic acid) exhibits a strong spectral overlap between the UV-visible absorption bands of Fe³⁺ ions and the emission spectrum of the host framework. In contrast, a negligible spectral overlap is observed with other metal ions, enabling the highly selective detection of Fe³⁺. This Förster resonance energy transfer (FRET)-based mechanism facilitates efficient fluorescence quenching specifically for Fe³⁺, distinguishing it from competing metal species (Fig. 3a).²³ Moreover, the mono-pyridyl functionalized [Zr₆O₄(OH)₄(PPDC)₅], (UiO-67@N, H₂PPDC = 2-phenylpyridine-5,4′-dicarboxylic acid) exhibits a highly selective and sensitive response to Fe³⁺ ions based on the mechanism of FRET and photo-induced electron transfer (PET) with an LOD as low as 0.156 ppm.²⁴

Besides, fluorescence quenching may also occur when the energy absorbed by the fluorescent ligand is competitively suppressed. This effect arises from competitive energy absorption, specifically when the absorption band of the metal ions overlaps spectrally with the excitation wavelength of the fluorescent ligand in the MOF. For example, [Cd₁₇(TCBPE)₁₂] (H₄TCBPE = 4′,4′′,4′′′,4′′′′-(ethene-1,1,2,2-tetrayl)tetrabiphenyl-4-carboxylic acid) exhibits high sensitivity and selectivity toward Fe³⁺ and MnO₄⁻ ions in various solvents due to fluorescence quenching. This quenching behavior arises from competitive energy absorption between these analytes and the TCBPE⁴⁻ ligand.²⁵ Similarly, the overlap between the ultraviolet absorption spectrum of [Tb₆(TDPAT)₄(μ₂-O)₃] (H₆TDPAT = 5,5′,5′′-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)triisophthalic acid) and the absorption spectrum of Fe³⁺ ions can significantly affect the energy absorption of the TDPAT⁶⁻ ligand, enabling selective detection of Fe³⁺ ions via fluorescence quenching. In other words, the excited-state energy within the MOF is competitively absorbed by Fe³⁺, disrupting energy transfer from the TDPAT⁶⁻ ligand to the Tb³⁺ center, which results in fluorescence quenching.²⁶

In addition to the mechanisms, the fluorescence performance of MOFs is further influenced by synergistic interactions between metal ions and fluorescent ligands. These interactions include competitive absorption of excitation/emission light, electronic structure modulation, and enhanced energy transfer efficiency. For example, the porphyrin functional MOF, [Zr₆O₈(TCPP)₄] (H₄TCPP = 4,4,4,4-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid)), serves as an effective fluorescent sensor for the sensitive and selective detection of Hg²⁺ ions via luminescence quenching. This quenching behavior arises from the combination of strong coordination interactions between the TCPP⁴⁻ ligand and Hg²⁺ ions and electron transfer from the TCPP⁴⁻ donor to the Hg²⁺ acceptor.²⁷ Similarly, [Cd₃(NTB)₂(BIPY)] (Cd-MOF, H₃NTB = 4,4′,4′′-nitrilotribenzoic acid, BIPY = 4,4′-bipyridine) functions as a multi-functional fluorescent sensor for Fe³⁺ and Hg²⁺ ions, exhibiting high sensitivity, selectivity, and efficiency, attributed to the synergistic effects of weak interactions (such as coordination or electrostatic interactions) and energy transfer between the MOF framework and the target metal ions (Fe³⁺/Hg²⁺)(Fig. 3b).²⁸ Besides, [(Zr₆O₄(OH)₄(PATP)₅)@PVP] (dMOR-2@PVP, H2PATP = 2-(aminomethyl) pyridine-1-ium terephthalic acid, PVP = polyvinylpyrrolidone) exhibits high selectivity and sensitivity for the detection of Cu²⁺, Pb²⁺, and Hg²⁺, with LODs of 0.59, 1.33 and 1.35 ppb, respectively, and the mechanism of which can be attributed to the synergistic interactions of stronger binding affinity, unique chelation and electronic effects.²⁹ In summary, the synergistic interactions between metal ions and fluorescent ligands in MOFs significantly enhance the detection performance for metal ions (such as Hg²⁺ and Fe³⁺), achieving high sensitivity and selectivity. MOF-based fluorescence quenching sensors can selectively detect metal ions based on fluorescence quenching behavior, which is derived from the host–guest interaction between the host framework and target metal ions. However, the performance is also related to competitive ions and pH changes.

MOF-based fluorescence enhancement sensors

Compared to fluorescence quenching, fluorescence enhancement offers distinct advantages in cases where the initial luminescence intensity is low, leading to higher signal-to-noise ratios and improved sensor sensitivity.³⁰ To our knowledge, fluorescence enhancement mechanisms mainly include excited-state intramolecular proton transfer (ESIPT), absorbance-caused enhancement (ACE), metal–ligand coordination interactions, and the suppression of non-radiative energy transfer pathways.

Currently, only a few MOFs can effectively detect heavy metal ions through ESIPT or ACE mechanisms. For example, the chemosensor [Al(OH)(BDC)(HFSA)], modified via a Schiff-base reaction with 3-formylsalicylic acid (3-HFSA), exhibits fluorescence enhancement toward Zn²⁺ ions. The –OH groups and nitrogen lone pair electrons chelate Zn²⁺ ions, suppressing –CN– isomerization and blocking ESIPT via phenolic proton chelation.³¹ Similarly, an “off–on–off” platform based on [(Zr₆O₄(OH)₄(DHTPA)₆)] (H₆DHTPA = 2,5-dihydroxyterephthalic acid) enables sequential Al³⁺ detection. The coordination with –OH groups stabilizes the ESIPT state, resulting in enhanced emission intensity. This result demonstrates that the capability of the MOF to detect challenging ions depends on competitive coordination effects.³² Besides, the hydrogen bonds were destroyed within [Mg₃(OH)(TPP)(DHBDC)₃] (H₂DHBDC = 2,5-dihydroxybenzene-1,4-dicarboxylic, TPP = 2,4,6-tri(4-pyridyl)pyridine) due to the formation of coordination bonds between Al³⁺ and –OH groups, inhibiting the ESIPT process. This behavior induces fluorescence quenching and enables the specific detection of Al³⁺ ions.³³

Meanwhile, ACE mechanisms can also induce fluorescence enhancement. [Co₃(BIBT)₃(BTC)₂(H₂O)₂] (JXUST-2, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole, H₃BTC = 1,3,5-benzenetricarboxylic acid) serves as a multifunctional sensor for Fe³⁺, Cr³⁺, and Al³⁺ ions, with the LODs of 0.13, 0.10, and 0.10 μM, respectively. Notably, JXUST-2 represents the first reported MOF sensor capable of simultaneous turn-on detection for multiple ions.³⁴ Similarly, [Zn₂(NDC)₂(BPDH)] (H₂NDC = 2,6-naphthalenedicarboxylic acid, BPDH = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene) can promote excited-state electron transition based on the specific coordination between the –CN group and Cr³⁺, Al³⁺ and Fe³⁺ ions and ultimately achieve fluorescence “turn-on” sensing based on the ACE mechanism.³⁵ Besides, the fluorescence enhancement sensor of [Cu(HBTC)(INP)] (H₃BEC = 1,3,5-benzene tricarboxylic acid, INP = 1,8-naphthalimide) exhibits selectivity to Fe³⁺, Cr³⁺, and Al³⁺ with an LOD reaching to 10⁻⁸ M, which is the combination result of the ACE and hydrogen bond destruction.³⁶

Additionally, the interaction between metal ions and ligands can significantly influence fluorescence performance. For example, the strong coordination between Al³⁺ ions and –NH₂ groups within of [Co₂(DATRz)(ABDC)₂] (HDATRz = 3,5-diamino-1,2,4-triazole) enhances light absorption and promotes efficient energy release. This results in a pronounced fluorescence “turn-on” response for Al³⁺ detection.³⁷ Organic ligands can serve as “antennas” by absorbing the excitation energy and transferring it to metal centers, particularly lanthanides, thereby amplifying the luminescence intensity.³⁸ A notable example is the boric acid-functionalized MOF, [Eu₂(BODBC)₃] (H₂BODBC = 5-boron-1,3-benzenedicarboxylic acid), which exhibits ultra-sensitive “turn-on” detection of CH₃Hg⁺ and Hg²⁺. Upon excitation at 275 nm, this MOF displays characteristic Eu³⁺ emission peaks at 620 nm (⁵D₀ → ⁷F₂) and 595 nm (⁵D₀ → ⁷F₁), confirming the antenna effect. Interestingly, this effect is quenched in aqueous solution due to the electron-withdrawing nature of the BA group. However, it is restored upon binding CH₃Hg⁺ or Hg²⁺ ions, as the formation of a C–B bond mitigates the quenching (Fig. 4a).³⁹ Similarly, [Zn₃(NMBP)₂(BPY)] (H₃NMBP = 4′,4′′′,4′′′′′-nitrilotris(3-methoxy-[1,1′-biphenyl]-4-carboxylic acid) and BPY =4,4′-bipyridine) exhibits significant fluorescence enhancement due to the coordination between Cd²⁺ ions and the nucleophilic N-sites of NMBP³⁻. This interaction enables direct visualization of the molecular diffusion within the crystal lattice, marking the first demonstration of such a process (Fig. 4b).⁴⁰

Besides, suppressing or reducing the energy transfer can significantly enhance the fluorescence intensity. For example, [Tb₉O₇(OH)(TCPP)₃] exhibits significant fluorescence enhancement (10-fold) in the presence of M³⁺ ions (Al³⁺, Cr³⁺ and Fe³⁺). The coordination bonds of Tb–O and energy transfer from TCPP⁴⁻ to Tb³⁺ ions result in weak fluorescence behavior. Upon M³⁺ binding, cation exchange disrupts the Tb³⁺–TCPP⁴⁻ energy transfer pathway, while simultaneously promoting π* → π transitions within TCPP⁴⁻. This dual modulation of energy transfer and π* → π transitions enables selective and sensitive M³⁺ detection (Fig. 4c).⁴¹ The incorporation of Cr³⁺ ions into [Eu₂(AIA)₃(DMF)₃] (H₂AIA = 5-[(anthracen-9-ylmethyl)-amino]-isophthalic acid) significantly reduces π–π stacking interactions between aromatic groups, thereby diminishing the self-absorption effect. Cr³⁺ ions facilitate charge transfer between aromatic groups or modulate excited-state energy levels, leading to substantial fluorescence enhancement.⁴² The tunable structural properties of MOFs make them ideal fluorescent sensors, and their luminescence intensity can be enhanced by the introduction of highly conjugated organic ligands, metal ions, or fluorescent guest molecules within the framework. Compared with these fluorescence quenching sensor signals, the fluorescence enhancement sensor is more practical for the significant response signal.

MOF-based electrochemical sensors

Unlike the aforementioned sensors, electrochemical sensors detect heavy metal ions through the redox reactions at the electrode surface, generating measurable changes in conductivity, voltage, and current.⁴³ For example, the sulfur-functionalized nano capsule MOF electrochemical sensor, [Co₂(TMC4R)(BDC)₂(μ₂-H₂O)] (Co-TMC4R-BDC/GCE, TMC4R = tetra(4-mercaptopyridine)calix[4]resorcinarene), demonstrates exceptional capture and detection performances for Cu²⁺, Pb²⁺, Cd²⁺, and Hg²⁺, with the LODs of 13, 11, 26, and 18 nM, respectively. These metal ions undergo redox reactions on the modified electrode surface, producing quantifiable current signals through square-wave anodic stripping voltammetry, where the current response correlates linearly with the ion concentration. The synergistic effect of sulfur–metal coordination bonds and cation⋯π interactions (between benzene rings and metal ions) enhances both metal capture efficiency and electrochemical detection sensitivity (Fig. 5a).⁴⁴ Similarly, the composite material [GA@(Zr₆O₄(OH)₄(ABDC)₃)], which integrates a graphene-based aerogel (GA) with UiO-66-NH₂, functions as an electrochemical sensor for detecting Cd²⁺, Pb²⁺, Cu²⁺and Hg²⁺via differential pulse stripping voltammetry. The GA component provides high conductivity and a porous structure, while UiO-66-NH₂ contributes a high specific surface area and abundant active sites, synergistically enhancing heavy metal ion interactions. This combination enables sensitive and selective detection through well-defined electrochemical reactions that generate measurable current signals.⁴⁵ Moreover, [[Zr₆O₈(OH)₁₆(TCPP)₃](MnCl)₃] (Mn-PCN-222) was deposited on a conductive indium tin oxide (ITO) surface to fabricate the Mn-PCN-222/ITO sensor. This sensor demonstrates the ability to detect redox-active analytes, including heavy metal ions, through both the redox-active porphyrin center and electrochemical reactions, generating current signals proportional to analyte concentrations (Fig. 5b).⁴⁶

Although MOF-based electrochemical sensors have advanced significantly in heavy metal ion detection, developing simpler and instrument-free detection methods remains a major challenge.

MOF-based colorimetric sensors

Colorimetric sensors, a class of optical sensors, enable rapid detection with simple operation. The detection mechanism is based on color changes, resulting from specific interactions between metal ions and MOFs.⁴⁷ For example, the functionalized MOF [Zn₂(OBA)₂(BPBE)], (TUM-59, H₂OBA = 4,4′-oxybis-benzoic acid, BPBE = N1,N4-bis-pyridin-4-ylethylidene-benzen-1,4-diamine) allows for the naked eye detection of Hg²⁺ based on a distinct color transition from colorless to pink, which is triggered by specific interactions between the MOF and Hg²⁺ ions (Fig. 6a).⁴⁸ Color changes in MOFs can also be induced by redox reactions. For example, the synergistic effect of –SH and –NH₂ groups in [Cu₂(AMT)₂(H₂O)] (Cu-MOF, H₂AMT = 3-amino-5-mercapto-1,2,4-triazole) facilitates the reduction of Cr⁶⁺ to Cr³⁺. Concurrently, the oxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) is oxidized to oxTMB, resulting in a rapid color transition from colorless to deep blue. This method demonstrates a wide linear range (0.2–100 μM) and a LOD of 0.023 μM (Fig. 6b).⁴⁹ Similarly, [Al(OH)(ABDC)(DHTA)] (DHTA = 12-(2′,4′-dihydroxyphenylazo terephthalic acid)) synthesized via the diazotization assembly of NH₂-MIL-53(Al) exhibits colorimetric sensing through coordination between the –NH₂ and phenolic –OH groups with Co²⁺ and Pd²⁺ ions, resulting in distinct color changes.⁵⁰ These investigations show that the performance of a colorimetric sensor is related to the pore size/shape, flexibility and host–guest interaction. Although the MOF-based colorimetric sensor provides rapid and convenient detection of metal ions without complicated equipment, the color change trace metal ions may be difficult to identify with naked eyes.

Conclusions

This review summarizes recent progress in MOF-based sensors for heavy metal ion detection, where the performance is fundamentally governed by host–guest interactions observable through fluorescence quenching, luminescence enhancement, electrochemical responses, and colorimetric changes. Although remarkable advancements have been achieved, MOF-based metal ion sensors must overcome the challenges including ultra-trace detection capability, high selectivity, stability, and portability in complex environments in application. The development directions focused on: 1) improving the selectivity based on the designation with precise recognition groups; 2) enhancing the signal response by combining the MOF with highly conductive materials; 3) increasing the specificity by introducing optical response features; 4) optimizing packaging and interfaces to ensure stability and enable device integration.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This work was supported by the Foundation of Department of Education of Guangdong Province (2023KTSCX152) and the Education Department of Guangdong Province (2022ZDJS027).

Notes and references

1. D. Dudgeon, A. H. Arthington, M. O. Gessner, Z.-I. Kawabata, D. J. Knowler, C. Lévêque, R. J. Naiman, A.-H. Prieur-Richard, D. Soto, M. L. J. Stiassny and C. A. Sullivan, Biol. Rev., 2006, 81, 163–182 CrossRef .
2. H. Ali and E. Khan, Toxicol. Environ. Chem., 2018, 100, 6–19 CrossRef CAS .
3. D. Wu, Y. Hu, H. Cheng and X. Ye, Molecules, 2023, 28, 3601 CrossRef CAS .
4. L. Si, Q. Wu, Y. Jin and Z. Wang, Front. Chem., 2024, 12, 1423666 CrossRef CAS .
5. T. Jia, Y. Gu and F. Li, J. Environ. Chem. Eng., 2022, 10, 108300 CrossRef CAS .
6. T. Chen and D. Zhao, Coord. Chem. Rev., 2023, 491, 215259 CrossRef CAS .
7. N.-Y. Huang, Y.-T. Zheng, D. Chen, Z.-Y. Chen, C.-Z. Huang and Q. Xu, Chem. Soc. Rev., 2023, 52, 7949–8004 RSC .
8. S. Sahoo, S. Mondal and D. Sarma, Coord. Chem. Rev., 2022, 470, 214707 CrossRef CAS .
9. C.-Y. Liu, X.-R. Chen, H.-X. Chen, Z. Niu, H. Hirao, P. Braunstein and J.-P. Lang, J. Am. Chem. Soc., 2020, 142, 6690–6697 CrossRef CAS .
10. X. Hao, W. Song, Y. Wang, J. Qin and Z. Jiang, Small, 2025, 21, 2408624 CrossRef .
11. J. Hu, S. Chen, Z. Liu, J.-R. Li, J.-H. Huang, Z. Jiang, W. Ou, W.-M. Liao, J. Lu and J. He, J. Mater. Chem. A, 2023, 11, 10577–10583 RSC .
12. E. F. Hasan Alzaimoor and E. Khan, Crit. Rev. Anal. Chem., 2024, 54, 3016–3037 CrossRef CAS .
13. H. N. Rubin and M. M. Reynolds, Inorg. Chem., 2019, 58, 10671–10679 CrossRef CAS .
14. Y. D. Farahani and V. Safarifard, J. Solid State Chem., 2019, 270, 428–435 CrossRef CAS .
15. R. Lv, H. Li, J. Su, X. Fu, B. Yang, W. Gu and X. Liu, Inorg. Chem., 2017, 56, 12348–12356 CrossRef CAS .
16. Z. Cui, X. Zhang, S. Liu, L. Zhou, W. Li and J. Zhang, Inorg. Chem., 2018, 57, 11463–11473 CrossRef CAS .
17. J. Xiu and G. Wang, Sens. Actuators, B, 2023, 374, 132837 CrossRef CAS .
18. G. Ji, J. Liu, X. Gao, W. Sun, J. Wang, S. Zhao and Z. Liu, J. Mater. Chem. A, 2017, 5, 10200–10205 RSC .
19. Y. Tang, H. Huang, W. Xue, Y. Chang, Y. Li, X. Guo and C. Zhong, Chem. Eng. J., 2020, 384, 123382 CrossRef CAS .
20. X.-F. Zhong, Z.-C. Ma, J.-J. Lin, Y. Wu, G. Liang, Y.-Y. Zhang, D.-J. Chen, K.-P. Xie, Z.-W. Mo and X.-M. Chen, Cryst. Growth Des., 2023, 23, 8793–8799 CrossRef CAS .
21. N. D. Rudd, H. Wang, E. M. A. Fuentes-Fernandez, S. J. Teat, F. Chen, G. Hall, Y. J. Chabal and J. Li, ACS Appl. Mater. Interfaces, 2016, 8, 30294–30303 CrossRef CAS .
22. L. Zhang, J. Wang, T. Du, W. Zhang, W. Zhu, C. Yang, T. Yue, J. Sun, T. Li and J. Wang, Inorg. Chem., 2019, 58, 12573–12581 CrossRef CAS .
23. N. Xu, Q. Zhang, B. Hou, Q. Cheng and G. Zhang, Inorg. Chem., 2018, 57, 13330–13340 CrossRef CAS .
24. S. Fajal, W. Mandal, D. Majumder, M. M. Shirolkar, Y. D. More and S. K. Ghosh, Chem. – Eur. J., 2022, 28, e202104175 CrossRef CAS .
25. P. Cen, T. Ma, F. Jiang, F. Zhang, Y. He, R. Ding and D. Tian, New J. Chem., 2023, 47, 16741–16747 RSC .
26. Y. Xiao, B. Li, Z. X. You, Y. H. Xing, F. Y. Bai, L.-X. Sun and Z. Shi, J. Mater. Chem. C, 2021, 9, 3193–3203 RSC .
27. E. Moradi, R. Rahimi and V. Safarifard, J. Solid State Chem., 2020, 286, 121277 CrossRef CAS .
28. H. Yang, D. Qi, X. Si, Z. Yan, L. Guo, C. Shao, W. Zhang and L. Yang, J. Solid State Chem., 2022, 310, 123008 CrossRef CAS .
29. S. A. Diamantis, A. D. Pournara, E. D. Koutsouroubi, C. Moularas, Y. Deligiannakis, G. S. Armatas, A. G. Hatzidimitriou, M. J. Manos and T. Lazarides, Inorg. Chem., 2022, 61, 7847–7858 CrossRef CAS .
30. T. K. Pal, Mater. Chem. Front., 2023, 7, 405–441 RSC .
31. R. M. Kamel, A. Shahat, Z. M. Anwar, H. A. El-Kady and E. M. Kilany, New J. Chem., 2021, 45, 8054–8063 RSC .
32. Q. Wang, X.-M. Du, B. Zhao, M. Pang, Y. Li and W.-J. Ruan, New J. Chem., 2020, 44, 1307–1312 RSC .
33. Y.-P. Li, X.-H. Zhu, S.-N. Li, Y.-C. Jiang, M.-C. Hu and Q.-G. Zhai, ACS Appl. Mater. Interfaces, 2019, 11, 11338–11348 CrossRef CAS .
34. X.-M. Tian, S.-L. Yao, C.-Q. Qiu, T.-F. Zheng, Y.-Q. Chen, H. Huang, J.-L. Chen, S.-J. Liu and H.-R. Wen, Inorg. Chem., 2020, 59, 2803–2810 CrossRef CAS .
35. D. Mukherjee, A. Pal, S. C. Pal, A. Saha and M. C. Das, Inorg. Chem., 2022, 61, 16952–16962 CrossRef CAS .
36. Q. Li, S. Shen, L. Liang, K. Huang, D. Zheng, D. Qin and B. Zhao, Dyes Pigm., 2023, 219, 111639 CrossRef CAS .
37. S. Chand, G. Verma, A. Pal, S. C. Pal, S. Ma and M. C. Das, Chem. – Eur. J., 2021, 27, 11804–11810 CrossRef CAS .
38. Q. Du, P. Wu, P. Dramou, R. Chen and H. He, New J. Chem., 2019, 43, 1291–1298 RSC .
39. H. Wang, X. Wang, M. Liang, G. Chen, R.-M. Kong, L. Xia and F. Qu, Anal. Chem., 2020, 92, 3366–3372 CrossRef CAS .
40. K. S. Lim, S. Y. Jeong, D. W. Kang, J. H. Song, H. Jo, W. R. Lee, W. J. Phang, D. Moon and C. S. Hong, Chem. – Eur. J., 2017, 23, 4803–4809 CrossRef CAS .
41. C. Fu, X. Sun, G. Zhang, P. Shi and P. Cui, Inorg. Chem., 2021, 60, 1116–1123 CrossRef CAS .
42. P.-P. Zhang, B. Song, Z. Li, J.-J. Zhang, A.-Y. Ni, J. Chen, J. Ni, S. Liu and C. Duan, J. Mater. Chem. A, 2021, 9, 13552–13561 RSC .
43. J. Dong, D. Zhang, C. Li, T. Bai, H. Jin and Z. Suo, Bioelectrochemistry, 2022, 146, 108134 CrossRef CAS .
44. F.-F. Wang, C. Liu, J. Yang, H.-L. Xu, W.-Y. Pei and J.-F. Ma, Chem. Eng. J., 2022, 438, 135639 CrossRef CAS .
45. M. Lu, Y. Deng, Y. Luo, J. Lv, T. Li, J. Xu, S.-W. Chen and J. Wang, Anal. Chem., 2019, 91, 888–895 CrossRef CAS .
46. Z. Zhou, S. Mukherjee, S. Hou, W. Li, M. Elsner and R. A. Fischer, Angew. Chem., Int. Ed., 2021, 60, 20551–20557 CrossRef CAS .
47. W. Sun, Y. Huo, X. Feng, L. Wei, X. Lu, S. Liu and Z. Gao, Coord. Chem. Rev., 2025, 535, 216638 CrossRef CAS .
48. S. Tarasi, A. Ramazani, A. Morsali and M.-L. Hu, Inorg. Chem., 2021, 60, 13588–13595 CrossRef CAS .
49. Y. Liu, Z. Mao, Y. You, B. Chang, L. Zhang and H. Chen, Water, Air, Soil Pollut., 2023, 234, 468 CrossRef CAS .
50. O. Alaysuy, A. Q. Alorabi, M. M. Aljohani, A. A. Alluhaybi, R. M. Snari, N. S. Bedowr, R. Shah and N. M. El-Metwaly, J. Water Process Eng., 2024, 59, 104993 CrossRef .

This journal is © The Royal Society of Chemistry 2025