Phosphatase-mimicking activity of a unique penta-nuclear zinc() complex with a reduced Schiff base ligand: assessment of its ability to sense nitroaromatics

• Published in: New journal of chemistry 2019-03, Vol.43 (11), p.4432-4443
• Main Authors: Karmakar, Mainak, Basak, Tanmoy, Chattopadhyay, Shouvik
• Format: Article
• Language: English
• Subjects: Crystallography; Fluorescence; Imines; Nitrobenzoic acid; NMR; Nuclear magnetic resonance; Phosphatase; Quenching; Spectrophotometry; Substrates; X-ray diffraction; Zinc compounds
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c8nj06549g

A unique penta-nuclear zinc( ii ) complex, [(μ 1,1 -N 3 ) 2 {(N 3 )Zn(L)Zn} 2 Zn(L)] {H 2 L= 2,2′-[(1-methyl-1,2-ethanediyl)bis(iminomethylene)]bis[6-methoxyphenol]}, has been synthesized and characterized. X-ray crystallographic analysis has confirmed its structure. The complex has shown good phosphatase-mimicking activity { k cat ∼ 398 h −1 at 298 K}, evaluated spectrophotometrically by monitoring the increase in absorbance at ∼425 nm, indicating gradual release of p -nitrophenolate by the hydrolysis of 4-nitrophenylphosphate ester with time, when 4-NPP (disodium 4-nitrophenylphosphate hexahydrate) has been used as a substrate. The complex behaves as a sensor for the detection of nitroaromatics in DMF solution via turn-off fluorescence response. The solution phase sensing mechanism has been studied and a strong quenching efficiency has been found with a quenching constant ( K SV ) of 6.497 × 10 4 M −1 for 3-methyl-4-nitrobenzoic acid. A penta-nuclear zinc( ii ) complex has been synthesized and characterized. The complex has shown good phosphatase-mimicking activity, which has been evaluated spectrophotometrically. The complex also behaves as a sensor for the detection of nitroaromatics via turn-off fluorescence response.