Detection of Cyanide Anion by Zinc Porphyrin–Spiropyran Dyad

Abstract

Cyanide is extremely toxic to living organisms including humans. Cyanide prevents oxygen uptake by binding to hemoglobin, myoglobin, and cytochromes. 1,2 It strongly binds to the iron constituent of cytochrome c, prevents transport of electrons from cytochrome c to oxygen, and inhibits mitochondrial energy production.The uses of cyanide are widespread in the chemical industry, gold mining, electroplating, case hardening of iron and steel, photographic applications, and organic chemicals and plastics manufacturing. 3 Moreover, cyanide is found throughout nature in more than 2000 plants and in substantial amounts in certain fruit seeds. 4 In plants, cyanides act as a natural self-defense mechanism against animal predation. Long-term consumption of cyanide-containing foods, such as cassava root or apricot seeds, may lead to cyanide poisoning. The maximum permissive level of cyanide in drinking water was reported at 1.9 μM by the World Health Organization (WHO). 5 Versatile methods of the sensitive and selective detection for cyanide anion to monitor toxic cyanide have been developed. These include colorimetric, fluorimetric, chromatographic, and electrochemical analyses. 6,7 Among those methods for cyanide detection, optical methods based on absorption and fluorescence spectroscopy are relatively simple, inexpensive, and sensitive. 8,9 A number of organic sensors for cyanide anion have been designed and synthesized. Absorption and/or fluorescence spectra of these sensors are changed by forming coordination complex or bonding covalently with cyanide. Compared with other anions, cyanide anion has some characteristic properties, such as its strong nucleophilicity and high binding affinity toward metal ions, and is superior and useful for the development of the sensors. Both covalent bond-based sensors and coordination complex-based sensors have been developed for cyanide detection. 6 Spiropyran derivatives have been extensively studied as typical photochromic molecules. 10,11 The colorless nonfluorescent spiropyran form is converted into colored fluorescent merocyanine form upon ultraviolet (UV) irradiation. The merocyanine form reverts into the spiropyran form upon exposure to visible light or thermal energy. Spiropyran has been reported as a selective, sensitive, and reproducible cyanide anion receptor, based on the covalent bond formation between spiropyran and nucleophilic cyanide anion. 9,12 UV irradiation of colorless spiropyran with cyanide anion results in the formation of yellow-colored merocyanine-cyanide adduct (absorbed at around 420 nm) by nucleophilic addition of cyanide anion to merocyanine (absorbed at around 520 nm) formed by photochemical ring-opening of spiropyran. Colorless spiropyran is reproduced from merocyanine-cyanide adduct by irradiation with visible light.Metalloporphyrins are intense-colored molecules that display a wavelength shift of Soret absorption band with different ligands. 13,14 Many metalloporphyrins are useful cyanide sensors because cyanide has high affinity for many metals in m...

Photochromism and Colorimetric Ion Sensing of a Spiropyran Derivative—Spiropyran‐Rhodamine Dyad

“…The structural interconversions could occur in response to a variety of the stimuli such as light, 14 heat, 15 mechanical forces, 16,17 or pH 6-9 as well as metal cations 1-6 and anions. [19][20][21] It is also widely found in nature such as plants and fruit seeds. 3,18 It is very crucial in many biochemical processes, such as oxygen transport, cellular metabolism, cofactor in enzymatic reactions, and transcriptional regulation.…”

“…3,18 It is very crucial in many biochemical processes, such as oxygen transport, cellular metabolism, cofactor in enzymatic reactions, and transcriptional regulation. 1,2,4,11,12,18,20 A fluorescent chemosensor is composed of a fluorescent dye and a receptor. [19][20][21] It is also widely found in nature such as plants and fruit seeds.…”

“…[19][20][21] It is also widely found in nature such as plants and fruit seeds. [14][15][16][17][20][21][22][23][24] We have previously reported a chemosensor system consisting of rhodamine (Rh) and spiropyran (SP) for the simultaneous detection of Al 3+ , HSO 3 − , and CN − ions. [6][7][8][9] The development of colorimetric and fluorescent chemosensors for the sensitive and accurate detection of Fe 3+ , CN − , and pH is a challenging task.…”

“…[19][20][21] It is also widely found in nature such as plants and fruit seeds. [19][20][21] It is also widely found in nature such as plants and fruit seeds.…”

“…1,2,4,11,12,18,20 A fluorescent chemosensor is composed of a fluorescent dye and a receptor. 1,2,4,11,12,18,20 A fluorescent chemosensor is composed of a fluorescent dye and a receptor.…”