Elsevier

Polyhedron

Volume 185, 15 July 2020, 114604
Polyhedron

Bifunctional chemosensor based on a dye-encapsulated metal-organic framework for highly selective and sensitive detection of Cr2O72− and Fe3+ ions

https://doi.org/10.1016/j.poly.2020.114604Get rights and content

Highlights

  • A three-dimensional protonated proflavin-encapsulated metal-organic framework was synthesized.

  • Compound 1 exhibits intense green emission in solution whereas it shows a strong red fluorescence in the crystal form.

  • The strong emission of 1 could be quenched by Fe3+ ions, even in the presence of other competing metal ions.

  • 1 exhibited superior selectivity and sensitivity towards Cr2O72− ions over other anions.

Abstract

A three-dimensional protonated proflavin (PF) encapsulated metal-organic framework, formulated as [Zn(NIPH)2(HPF)2] (1), has been successfully synthesized under hydrothermal conditions using the familiar and cheap ligand 5-nitroisophthalic acid (5-H2NIPH). The as-synthesized compound 1 exhibits an intense green emission in solution, whereas strong red fluorescence is observed in the crystal form. The strong green emission of 1 could be highly and selectively quenched by Fe3+ ions, even in the presence of other competing metal ions such as Ag+, Al3+, Ca2+, Cd2+, Co2+, K+, Mg2+, Mn2+, Na+ and Zn2+. In addition, 1 exhibits superior selectivity and sensitivity towards Cr2O72− ions over other anions including Br, CH3COO, Cl, F, H2PO4, HCO3, HPO42−, NO3, PO43− and SO42−. The possible luminescence quenching mechanisms were investigated. This work revealed that a dye-encapsulated MOF can be used as one of the most fascinating multi-response luminescence materials for selective chemical sensing.

Graphical abstract

A proflavin-encapsulated Zn(II)-based MOF was synthesized, which exhibited superior selectivity and sensitivity towards Cr2O72− and Fe3+ ions, even in the presence of other competing analytes.

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Introduction

With the increase of industrial and wastewater effluents, water pollution has become a serious threat for human and aquatic life at the present time. Detection of toxic species from contaminated water has been capturing much attention from researchers. Metal ions and anions are the most common pollutants in industrial waste. The Fe3+ ion is an essential component in many kinds of organisms [1] and it is involved in a variety of cell functions, such as hemoglobin formation, oxygen metabolism and electron transfer processes in DNA and RNA synthesis [2]. However, an excess of Fe3+ ions in the human body may cause damage to nucleic acids and proteins by generating reactive oxygen species (ROS) [3]. Meanwhile, unbalanced Fe3+ ions in the human body can induce dangerous diseases, such as anemia and insomnia [4]. On the other hand, despite of the fact that dichromate (Cr2O72−) anions are widely used in many industries, such as chromium electroplating, metallurgy, pigment production and leather tanning [5], [6], it is a well known carcinogen [7]. The consequences of long-term exposure to the Cr2O72− anion can cause several adverse health effects, including allergic reactions, hereditary genetic defects and lung cancer [8]. Therefore, developing highly efficient methods for the detection of Fe3+ and Cr2O72− ions is of great significance for environmental issue concerns.

Until now, various analytical methods, including chromatography coupled with mass spectrometry [9], atomic absorption spectrometry [10], inductively coupled plasma-atomic emission spectrometry [11], Raman spectroscopy and ion mobility spectrometry [12], have been employed to detect metal ions and anions. However, most of these techniques have high cost, poor portability, low sensitivity and are time consuming. In the past decade, fluorescence sensors based on metal-organic frameworks (MOFs) consisting of metal ions or clusters and organic ligands [13], [14], [15], [16] for detecting anions [17], metal cations [18], biomolecules [19], small organic molecules [20] and nitroaromatics [21] have attracted much attention because of their porosity, large surface area, tunable functional sites and supramolecular interaction between analytes and host frameworks [14], [15], [16]. However, it is still a challenging task to synthesize MOFs-based sensors for highly selective and sensitive detection of Fe3+ or Cr2O72− ions in the presence of other competing ingredients.

Recently, to improve the fluorescent properties of MOFs, many organic fluorescent dyes, such as rhodamines [22], cyanine [23], pyridine [24], fluorescein [25], perylene [26] and methyl red [27] have been considered as compounds to encapsulate into the channel or cages of MOFs. These traditional fluorescent dyes often suffer an aggregation-caused quenching (ACQ) effect that greatly restrains their applications in solid-state devices [28], but the MOFs can serve as an excellent host to reduce or even eliminate the ACQ effect through confinement [29]. At present, the main strategy for synthesizing a dye@MOF composite is still a multiple-step post functionalization chemical reaction, followed by cation exchanges [30], [31]. Therefore, investigation on a one-pot incorporate of dye@MOF composites with potent sensing performance is still in its infancy and remains a great challenge.

In this report, we have synthesized a dye-encapsulated metal-organic framework [Zn(NIPH)2(HPF)2] (1) under hydrothermal conditions by using the familiar and cheap ligand 5-nitroisophthalic acid (5-H2NIPH). Protonated proflavin (PF) molecules are situated in the channels of 1. Compound 1 exhibits a strong red emission color in the crystalline state and a green emission color in solution. Remarkably, the strong visual emission can be highly quenched by Fe3+ and Cr2O72− ions, even in the presence of other interfering analytes.

Section snippets

Chemical materials

All the starting materials were commercially purchased and used as received. Aqueous solutions of the metal ions (Ag+, Al3+, Ca2+, Cd2+, Co2+, Fe3+, K+, Mg2+, Mn2+, Na+ and Zn2+) with a concentration of 0.01 mol/L were prepared from their chloride or nitrate salts. Anion aqueous solutions (Br, CH3COO, Cl, F, H2PO4, HCO3, HPO42−, NO3, PO43−, SO42− and Cr2O72−) with a concentration of 0.01 mol/L were prepared from ammonium salts, including ammonium bicarbonate (NH4HCO3), ammonium acetate

Crystal structure of [Zn(NIPH)2(HPF)2] (1)

Compound 1 crystallizes in the orthorhombic space group, P212121 system. In the asymmetric unit, each Zn(II) center is coordinated by four carboxylate oxygen atoms of four different NIPH ligands (Fig. 1a). The Zn-O distances are in the range 1.922(5) to 2.008(6) Å and are in good agreement with those found in other extended structures constructed from the NIPH ligand [32], [33]. The O-Zn-O angles range from 98.3(2) to 119.3(2) °, indicating that each Zn center displays a distorted tetrahedral

Conclusions

In this study, we have synthesized a proflavin-encapsulated metal–organic framework with a non-interpenetrating 3-D framework by a hydrothermal reaction. The photoluminescent properties showed that the emission of 1 is mainly from the cationic dye. This compound shows a dual turn-off response to Cr2O72− and Fe3+ ions with high sensitivity. This work demonstrated that dye-encapsulated MOFs have great potential to serve as luminescent sensors in environmental areas.

CRediT authorship contribution statement

Muhammad Awais Akram: Formal analysis, Writing - original draft. Junwei Ye: Formal analysis, Writing - review & editing, Supervision. Guangyao Wang: Validation, Formal analysis. Lei Shi: Writing - review & editing, Formal analysis. Zhao Liu: Writing - review & editing. Hao Lu: Validation, Writing - review & editing. Siqi Zhang: Writing - review & editing. Guiling Ning: Writing - review & editing, Supervision.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (U1607101 and (U1808210) and the Fundamental Research Funds for the Central Universities of China (DUT20LK37).

References (43)

  • R.F. Bogale et al.

    Sens. Actuators. B

    (2017)
  • B. Dhal et al.

    J. Hazard. Mater.

    (2013)
  • H.B. Zhu et al.

    Inorg. Chem. Commun.

    (2019)
  • J.P. Zheng et al.

    Chem Plus Chem

    (2016)
  • D.J. Zhang et al.

    Polyhedron

    (2016)
  • J.Q. Liu et al.

    Front. Chem.

    (2019)
  • J.C. Jin et al.

    CrystEngComm

    (2017)
  • Y.W. Shi et al.

    Dalton Trans.

    (2018)
  • R.F. Bogale et al.

    Dalton Trans.

    (2016)
  • C.M. Tomp Son, C.R. Kir Man, D.M. Proctor, L.C. Haws, M. Suh, S.M. Hays, J.G. Hixon, M.A. Harris, J. Appl. Toxicol. 34...
  • Z.J. Lin et al.

    Inorg. Chem.

    (2017)
  • Z. Sun et al.

    Cryst. Growth Des.

    (2017)
  • K. Håkans Son, R.V. Coorey, R.A. Zubarev, V.L. Talrose, P. Håkans son, J. Mass Spectrom. 35 (2000)...
  • Z.M. Sun et al.

    Microchim. Acta

    (2008)
  • F. Seby et al.

    J. Anal. At. Spectrom.

    (2003)
  • Y. Rachuri et al.

    Dalton Trans.

    (2016)
  • Y.H. Zhang et al.

    J. Mater. Chem. C

    (2017)
  • X.Y. Guo et al.

    J. Mater. Chem. A

    (2017)
  • A.K. Jana et al.

    Chem Plus Chem

    (2017)
  • S.A.A. Razavi et al.

    Inorg. Chem.

    (2017)
  • N. Bhardwaj et al.

    Biosens. Bioelectron.

    (2016)
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