Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing

Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknow...

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Bibliographic Details
Published in:Chemosensors 2021-10, Vol.9 (10), p.278
Main Authors: Konrad, Nele, Horetski, Matvey, Sihtmäe, Mariliis, Truong, Khai-Nghi, Osadchuk, Irina, Burankova, Tatsiana, Kielmann, Marc, Adamson, Jasper, Kahru, Anne, Rissanen, Kari, Senge, Mathias O., Borovkov, Victor, Aav, Riina, Kananovich, Dzmitry
Format: Article
Language:English
Subjects:
Binding
Binding sites
Biodegradation
Biodiversity and Ecology
Catalysts
Chemical Sciences
Chemicals
chiral amine
Chirality
Circular dichroism
Computer applications
Coordination chemistry
Dichroism
Dipoles
Ecotoxicology
Environmental Sciences
host–guest binding
Hydrogen
Lewis acid
Life Sciences
Organic compounds
organocatalyst
Pollutants
porphyrin
Porphyrins
Sensors
Single crystals
Software
Spectroscopy
Takemoto’s catalyst
Thiourea
Thioureas
Toxicity
Toxicity testing
Toxicology
X-ray diffraction
Zinc
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Summary:Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant toxicity of Takemoto’s catalyst (EC50 = 7.9 mg/L) and its NH2-substituted analog (EC50 = 7.2–7.4 mg/L). The observed toxic effect was pronounced by the influence of the trifluoromethyl moiety. En route to the porphyrin-based chemosensing of Takemoto-type thioureas, their supramolecular binding to a series of zinc porphyrins was studied with UV-Vis and circular dichroism (CD) spectroscopy, computational analysis and single crystal X-ray diffraction. The association constant values generally increased with the increasing electron-withdrawing properties of the porphyrins and electron-donating ability of the thioureas, a result of the predominant Zn⋯N cation–dipole (Lewis acid–base) interaction. The binding event induced a CD signal in the Soret band region of the porphyrin hosts—a crucial property for chirality sensing of Takemoto-type thioureas.
ISSN:2227-9040
2227-9040
DOI:10.3390/chemosensors9100278