Spirooxazine-Based Dual-Sensing Probe for Colorimetric Detection of Cu²⁺ and Fe³⁺ and Its Application in Drinking Water and Rice Quality Monitoring

Abstract

A spirooxazine derivative, PheSPO (3,3-dimethyl-1-phenethylspiro[indoline-2,3′-naphtho[2,1- b ][1,4]oxazine]), as a dual-sensing probe for Cu 2+ and Fe 3+ was synthesized, and its structure was confirmed by 1 H NMR, 13 C NMR, HRMS, and single-crystal X-ray diffraction. The results reveal that the PheSPO probe is selective to both Cu 2+ and Fe 3+ through distinct colorimetric responses in acetonitrile. The sensing performance of PheSPO toward Cu 2+ was investigated, and upon addition of Cu 2+ , an instant change in color from colorless to bright yellow with a strong absorption band at 467 nm was observed. Due to a dual-sensing behavior, PheSPO also exhibits a unique response toward Fe 3+ that can be discovered from a color change from colorless to red at an absorption wavelength of 514 nm. Based on spectroscopic analyses and density functional theory calculations, the 1:1 stoichiometric complexation of PheSPO with the targeted metal ions was proposed and the binding constants of 1.95 × 10 3 M –1 for Cu 2+ and 1.29 × 10 3 M –1 for Fe 3+ were obtained. In addition, the detection limits of PheSPO for Cu 2+ and Fe 3+ were 0.94 and 2.01 μM, respectively. To verify its applicability in real samples, PheSPO was further explored for quantitative determination of both Cu 2+ and Fe 3+ in spiked drinking water. The results showed that the recoveries of Cu 2+ and Fe 3+ examined using the PheSPO probe were found comparable to those obtained from atomic absorption spectroscopy. Moreover, the PheSPO strip test was developed, and its utilization for qualitative detection of Fe 3+ in real rice samples was demonstrated.

Photoswitchable Photochromic Chelating Spironaphthoxazines: Synthesis, Photophysical Properties, Quantum-Chemical Calculations, and Complexation Ability

“…That is why the spirooxazines are extensively developed and investigated. The continuous search of photoswitchable materials with suitable photochromic, molecular switching, and light-emissive characteristics and enhanced sensing feasibility has led to the production of various spirooxazine derivatives and materials based on them, attractive for diverse applications …”

Synthesis and characterization of a rhodamine derivative as a selective switch-on fluorescent sensor for Cu2+ ions in aqueous PBS buffer and living cells

“…[29][30][31][32][33] In the past few decades, a variety of organic molecules such as rhodamine, coumarinbenzopyrylium, benzothiadiazole, anthracene, phenothiazine, and squaraine have been synthesized and are being studied as possible chemosensors that can detect a variety of metal ions. [34][35][36][37][38][39] However, high detection limits, significant interference from other ions and lower wavelengths of excitation and emission when detecting Cu 2+ are only a few of the drawbacks of several fluorescent molecular probes reported in the literature.…”

Meglumine‐based Sustainable Three‐component Deep Eutectic Solvent Applicable for the Synthesis of Pyrazolo[5,1‐b]quinazoline‐3‐carboxylates as a Sensing Probe for Cu2+ Ions

“…On the other hand, in many essential transition metal ions, copper plays a vital role in various biological processes such as catalysis, metabolism, and signaling. [23] Along with this, copper is widely present in soil and water; also, a certain level of copper is essential to the good health of humans, animals, and plants. [24] Moreover, it plays a crucial role in the human body, for instance, ATP production, iron absorption, catecholamine biosynthesis, [23] mitochondrial electron transport chain function, [25] as a catalytic cofactor for different metalloenzymes such as Cu/Zn superoxide dismutase, cytochrome c oxidase, ceruloplasmin, dopamine β monooxygenase, and tyrosinase.…”

“…[23] Along with this, copper is widely present in soil and water; also, a certain level of copper is essential to the good health of humans, animals, and plants. [24] Moreover, it plays a crucial role in the human body, for instance, ATP production, iron absorption, catecholamine biosynthesis, [23] mitochondrial electron transport chain function, [25] as a catalytic cofactor for different metalloenzymes such as Cu/Zn superoxide dismutase, cytochrome c oxidase, ceruloplasmin, dopamine β monooxygenase, and tyrosinase. [26,27] Deficiency in copper intake may result in haematological and neurodegenerative diseases, including myelodysplasia, leukopenia, [28] Menke's, Alzheimer's, Wilson's, prion disease, [23,24,26,29] cellular damage, [30] and familial amyotrophic lateral sclerosis.…”

“…[24] Moreover, it plays a crucial role in the human body, for instance, ATP production, iron absorption, catecholamine biosynthesis, [23] mitochondrial electron transport chain function, [25] as a catalytic cofactor for different metalloenzymes such as Cu/Zn superoxide dismutase, cytochrome c oxidase, ceruloplasmin, dopamine β monooxygenase, and tyrosinase. [26,27] Deficiency in copper intake may result in haematological and neurodegenerative diseases, including myelodysplasia, leukopenia, [28] Menke's, Alzheimer's, Wilson's, prion disease, [23,24,26,29] cellular damage, [30] and familial amyotrophic lateral sclerosis. [24] Also, the elevated level of copper in a growing plant medium produces reactive oxygen species, which can diminish the photosynthesis activity and ultimately, the growth of herbs.…”