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Papers by Tania Chowdhury

Crystal Growth & Design, 2020

Two newly synthesized Fe(III) based complexes, [Fe 4 L 2 9= 3-O) 2 (Cl) 2 (MeOH) 4 (H 2 O) 4 ](Cl... more Two newly synthesized Fe(III) based complexes, [Fe 4 L 2 9= 3-O) 2 (Cl) 2 (MeOH) 4 (H 2 O) 4 ](ClO 4) 2. 4H 2 O. MeOH (1) and [Fe 2 L 3 ]. 4DMF (2) were isolated as solid crystalline form using the reaction of iron(III) perchlorate with the ligand H 2 L (H 2 L = 6,6'-((1E,1'E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(2-methoxyphenol). (DMF= N,Ndimethylformamide, MeOH = methanol). Compound 1 was self-assembled in MeOH but when solvent was changed to DMF, compound 2 was harvested. Further, compound 1 was converted to compound 2 just by dissolving compound 1 in DMF. Sequential self-assembly and conversion of compound 1 to 2 were monitored by UV-Vis spectroscopy and ESI-Mass spectroscopy in solution phase. Single crystal X-ray analysis showed that compound 1 has = 3-oxo bridged tetranuclear structure whereas compound 2 has puckered di-nuclear structure. Magnetic studies indeed revealed frustrated magnetic spin for compound 1 whereas antiferromagnetic interaction was observed for compound 2. The spectrophotometrical investigation on their phosphatase like activity revealed remarkable hydrolytic efficiency for both the complexes. $ # E * " kinetic parameters suggest the competitiveness of the rate of (E> bond fission employing the phosphomonoester (4-nitrophenyl)phosphate (PNPP) in 97.5% DMF is 1>2 and the k cat value lies in the range 28.95-38.43 s E4 at 298 K. Computational calculations have verified the higher catalytic

Dalton Transactions

Two highly luminescent Zn(ii) homologous Schiff base complexes (D1, D2) have been demonstrated hi... more Two highly luminescent Zn(ii) homologous Schiff base complexes (D1, D2) have been demonstrated highlighting D1 as a potent on–off chemosensor to detect arsenate in polluted water in light of computational mechanistic approach.

ACS Applied Materials & Interfaces, 2020

In this work a green, sustainable and efficient protocol for the syntheses of dihydroquinazoline ... more In this work a green, sustainable and efficient protocol for the syntheses of dihydroquinazoline derivatives is proposed. Initially, three Schiff base complexes of iron containing the ligand (2,2dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))bis(2,4-Xphenol), where X= Cl (complex 1) / Br (complex 2) / I (complex 3) were synthesized, fully characterized and used in the desired syntheses. Complex 1 excelled as a catalyst closely followed by complexes 2 and 3. DFT calculations helped in rationalising the role of halide substituent in the ligand backbone as a relevant factor in the catalytic superiority of complex 1 over complexes 2 and 3 for the synthesis of the dihydroquinazoline derivatives. Finally, to facilitate catalyst recoverability and reusability, complex 1 was immobilized on GO@Fe 3 O 4 @APTES (GO = Graphene Oxide; APTES = 3-aminopropyltriethoxysilane) to generate GO@Fe 3 O 4 @APTES@FeL 1 (GOTESFe). GOTESFe was thoroughly characterized through scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy, and efficiently used for the synthesis of dihydroquinazoline derivatives. GOTESFe could be magnetically recovered and reused up to five cycles without compromising its catalytic efficiency. Therefore, immobilization of the chose iron complex onto magnetic GO sheets offers an extremely competent route in

Journal of Coordination Chemistry, 2020

ACS Applied Bio Materials, 2020

Six zinc(II) complexes namely [Zn(HL 1 H)Cl 2 ] (1), [Zn(HL 1 H)Br 2 ] (2), [Zn 2 (HL 1 H) 2 (OH)... more Six zinc(II) complexes namely [Zn(HL 1 H)Cl 2 ] (1), [Zn(HL 1 H)Br 2 ] (2), [Zn 2 (HL 1 H) 2 (OH)I 2 ]. I (3), [Zn(HL 2)Cl] (4), [Zn 2 (HL 2)Br 3 ] (5) and [Zn(HL 2)I] (6) have been manufactured by using two homologous Schiff base ligands H 2 L 1 and H 2 L 2 for the purpose to perlustrate their phosphatase like activity, anti-oxidant activity and anti-bacterial activity. Complexes 1, 2, 4 and 5 have been reported earlier by us whereas complexes 3 and 6 have been synthesised and structurally characterised by regular physicochemical methods The hydrolytic property of the six complexes has been evaluated by checking the hydrolysis of P-O bond of widely used substrate namely di-sodium salt of (para-nitrophenyl)phosphate (PNPP) in 97.5% (v/v) mixture of N,N-dimethylformamide and water (DMF-water). Complexes 2-5 have profound efficiency towards hydrolysis of phosphate ester bond and complexes 1, 6 were noted to be inactive towards hydrolysis. Complex 3 displayed the highest efficacy among six complexes. Additionally anti-oxidant and anti-bacterial activities of the complexes were studied thoroughly. Detailed study of their anti-oxidant property revealed that complex 3 manifested superior radical scavenging activity, thus exhibiting the highest anti-oxidant property. The anti-bacterial activity was tested using the four investigating bacteria specifically Listeria monocytogenesATCC ® 19111™, Staphylococcus aureus ATCC ® 700699™, Salmonella typhimurium ATCC ® 23564™ and Escherichia coli ATCC ® 25922™ by determining Minimum Inhibitory Concentration (MIC) values using microdilution method. Here as well, complex 3

Applied Organometallic Chemistry, 2020

Four new zinc (II) complexes [Zn (HL 1 H)Br 2 ] (1), [Zn (HL 1 H)Cl 2 ] (2), [Zn 2 (HL 2)Br 3 ] (... more Four new zinc (II) complexes [Zn (HL 1 H)Br 2 ] (1), [Zn (HL 1 H)Cl 2 ] (2), [Zn 2 (HL 2)Br 3 ] (3), and [Zn (HL 2)Cl] (4) have been synthesized by adopting template synthetic strategy and utilizing two homologous Schiff base ligands (H 2 L 1 = 4-bromo-2-{[2-(2-hydroxyethylamino)-ethylimino]-methyl}-6-methoxyphenol, H 2 L 2 = 4-bromo-2-{[3-(2-hydroxyethylamino)propylimino]methyl}-6-methoxyphenol), differing in one-CH 2-unit in the ligating backbone, by adopting template synthetic strategy. All the complexes have been characterized by single crystal X-ray diffraction analysis as well as by other routine physicochemical techniques. Ligand mediated structural variations have been observed and rationalized by density functional theoretical (DFT) calculations. Interaction of the complexes 1-4 with Bovine Serum Albumin protein (BSA) has been studied by different spectroscopic techniques. A complete thermodynamic profile (ΔH o , ΔS o and ΔG o) was evaluated initially from the change in absorption and fluorescence spectra upon addition of BSA to the complexes. Appreciable binding constant values in the range~0.94-4.51 × 10 4 M −1 indicate efficient binding tendency of the complexes to BSA with the sequence 1 ffi 2 > 3 ffi 4. Circular dichroism (CD), isothermal calorimetric titration experiments, molecular docking and molecular dynamics have been performed to gain deep insight into the binding regions of complex 1 to BSA. Experimental evidences suggest an interaction of zinc complexes at the surface of BSA protein and this particular binding has been exploited to determine unknown concentration of BSA protein. For this purpose complex 1 was explored as a BSA protein quantification tool.