Bibhutosh Adhikary

CuS nanoparticles as a mimic peroxidase for colorimetric estimation of human blood glucose level

CuS nanoparticles (NPs) was synthesized through a simple and green method using water soluble precursor complex [CuL2(H2O)2]Cl2 (L=pyridine 2-carboxamide) and was characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) and UV-Vis spectroscopic techniques. The as-prepared CuS NPs (covellite) was demonstrated to possess intrinsic peroxidase-like activity using 3,3,5,5-tetramethylbenzidine (TMB), as a peroxidase substrate, in presence of H2O2 which show good affinity towards both TMB and H2O2. Using this TMB-H2O2 catalyzed color reaction; the CuS NPs was exploited as a new type of biosensor for detection and estimation of glucose through a simple, cheap and selective colorimetric method in a linear range from 2 to 1800 μM with a detection limit of 0.12 μM. On the basis of the developed reaction process, we can easily monitor human blood glucose level.

Dinuclear metal complexes. Part 4. Electrochemical studies of macrocyclic dicopper(II) complexes. Investigation of the effect of solvents, donor groups, and steric constraints on the stability of mixed-valence copper(II)–copper(I) complexes

Two series of macrocyclic dicopper(II) complexes of stoicheiometry [Cu2L][ClO4]2·2H2O have been synthesized and characterized. Compounds belonging to series (1) are derived from the 6,12,18,24-substituted (H,H,Me,Me; H,H,Me,Ph; Me,Me,Me,Ph; Me,Me,Ph,Ph) macrocycie 7,11;19,23-dimetheno-9,21-dimethyl-1,5,13,17-tetra-azacyclotetracosa-5,7,9,12,17,19,21,24-octaene-25,26-diol (H2L). Complexes belonging to series (2) are related to those of series (1) by replacement of two of the –CHN– linkages by –CH2–NH– groups and the segment containing two azomethine linkages having the 6,12-substituents H,H; Me,Me; Me,Ph; Ph,Ph. The electrochemistry of these compounds has been investigated in MeCN and CH2Cl2 solvents using platinum and glassy carbon electrodes. In all cases cyclic voltammograms show sequential one-electron transfers at two different potentials, and from these data the conproportionation constant (Kc) and free energy of the mixed-valent species (ΔGc) have been evaluated. Electrochemical results have been analysed in terms of the effect due to solvent, donor groups, and steric constraints. Values of Kc for all of the compounds are greater in MeCN than those in CH2Cl2, and the Kc value for any compound belonging to series (1) is greater than its analogue in series (2). Factors affecting stability and intramolecular electron-transfer rates of CuIICuIL+ species are discussed.

A novel amperometric biosensor for hydrogen peroxide and glucose based on cuprous sulfide nanoplates

A facile, greener and template free route has been developed to produce cuprous sulfide (Cu2S) nanoplates (NPs) with average diameters of 70-150 nm, via one step solvothermal decomposition of a single-source precursor (SSP) Cu(ACDC)2 [ACDC = 2-aminocyclopentene-1-dithiocarboxylate] in the presence of ethylenediamine (EN) and triethylenetetramine (TETA) as structure orienting agents. The precursor complex and nanomaterials were thoroughly characterized by several common techniques and measurements, which give the composition and characteristics of the materials. Amperometric biosensors for hydrogen peroxide (H2O2) and glucose have been constructed by immobilizing the synthesized Cu2S NPs in glutaraldehyde on a glassy carbon (GC) electrode using a direct drop-coating method. The proposed sensor has displayed faster response, high and reproducible sensitivity (64.27 μA mM-1) with linear range of 10 μM to 3.75 mM, towards the electrochemical biosensing of H2O2 at -0.35 V (vs. Ag/AgCl). The sensor also showed high and reproducible sensitivity (61.67 μA mM-1) towards glucose determination with linear range of 10 μM to 3.1 mM. The anti-inference ability of electroactive molecules and favorable stability are some of the advantages of the proposed sensor. Finally, using the sensor we have determined the glucose concentration in a human blood serum sample. The results strongly demonstrate the usefulness of Cu2S NPs for biosensor design and other biological applications.

A correlation involving ^1H NMR spectra and exchange coupling constants of a family of phenoxo-bridged macrocyclic dicopper(II) complexes

The 1H NMR spectra of eleven macrocyclic tetraiminodiphenolate dicopper(II) complexes derived from 4-methyl (or tert-butyl)-2,6-diformyl/diacetyl/dibutyrylphenols and linker diamines such as 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane or 1,2-diaminobenzene have been studied in (CD3)2SO at 25 °C. The hyperfine-shifted 1H NMR signals have been assigned from their measured longitudinal relaxation times (T1) and peak areas. The two copper(II) centres in these compounds are strongly antiferromagnetically coupled with the exchange coupling constant −2J (H n= n−2JS1·S2) lying between 690 and 860 cm−1. It is shown that a plot of the chemical shift (δ) due to the phenolate ring protons of the nmacrocycles at 298 K s. the exchange coupling constant (−2J) of the corresponding complexes provides a smooth sigmoidal curve that can be simulated by the expression −2J n= 220.6 [1 + exp{(δ n− 4.12)/2.93}]−1 n+ 667.

Preparation, characterization, reactivities and electrochemistry of some homo- and heterodinuclear complexes of 2-hydroxy-5- methylbenzene-1,3-dicarbaldehyde and 1,3-diacetyl- 2-hydroxy-5-methylbenzene

Abstract Homo- and heterodinuclear complexes of composition [M 2 L 2 ](ClO 4 ) 2 ·4H 2 O, [CuML 2 ](ClO 4 ) 2 · n H 2 O (M = Ni, Co or Mn; L = L 1 or L 2 ) and [CuML 2 Cl 2 ]·2H 2 O (M = Ni or Co) have been synthesized with the dinucleating ligands 2-hydroxy-5-methyl- benzene-1,3-dicarbaldehyde (HL 1 ) and 1,3-diacetyl-2-hydroxy-5-methylbenzene (HL 2 ). These compounds have been characterized and their chemical reactivities investigated. The electrochemical behaviour of [M 2 L 2 2 ](ClO 4 ) 2 ·4H 2 O and [CuML 2 2 ](ClO 4 ) 2 · n H 2 O complexes have been examined in acetonitrile and dimethyl sulfoxide using Hg and Pt electrodes. The cyclic voltammograms obtained with a Hg electrode show quasi-reversible electron transfers for both metal centres that often get complicated due to decomplexation of metal ions and adsorption phenomena. On a Pt electrode irreversible electron transfers occur at more negative potentials.

Synthesis, characterization and electrochemistry of copper(II), nickel(II), cobalt(II) and zinc(II) complexes of a binucleating ligand with [N2S]2O donors

Abstract A heptadentate ligand (H 3 L) with a phenoxo group bridging two metal centres has been synthesized by reacting 4-methyl-2,6-diformylphenol with methyl 2-((2-aminoethyl)amino)cyclopent-l-enedithiocarboxylate. Mono- and binuclear complexes of copper(II), nickel(II), cobalt(II) and zinc(II) have been synthesized and characterized by their UV—vis, IR, 1 H and 13 C NMR and EPR spectra. The electrochemistry of the complexes has been studied and the factors affecting electron-transfer reactions of the binuclear complexes vis-a-vis corresponding mononuclear complexes have been examined.

Dinuclear copper(II) complex mediated regioselective aldol-type condensation of 2-hydroxy-5-methylbenzene-1,3-dicarbaldehyde☆

Abstract An aldol-type reaction of one of the carbaldehyde moieties of 2-hydroxy-5-methylbenzene-1,3-dicarbaldehyde (HL) takes place with ketones containing α-methyl and/or α-methylene groups through an in situ generated dicopper(II) complex, Cu 2 L 2 (ClO 4 ) 2 · 2H 2 O. The metal-free condensation products are 2-hydroxy-3-formyl-5-methyl-1-benzal ketones. No such reaction takes place with the mononuclear complex CuL 2 · H 2 O. The ligand (HL) itself undergoes uncontrolled self-condensation and polycondensation.

E.p.r. spectra and bonding parameters of copper(II) complexes of 2-methyl-4,6-diacylphenols, of the dibenzoyl analogues and of some of their derivatives

SummaryThe e.p.r. spectra of mononuclear copper(II) complexes of 2-methyl-4,6-diacylphenols and dibenzoylphenols, and their condensation products with 1,3-diaminopropane have been examined. The MO coefficients evaluated from e.p.r. spectral parameters indicate that the in-plane-σ, in-plane-π and out-of-plane-π bondings are significantly covalent. The e.p.r. spectra of the macrocyclic dicopper(II) complexes derived from 2-methyl-4,6-diacyl(benzoyl)phenols and 1,3-diaminopropane measured at 77 K reveal the presence of mononuclear species of axial symmetry.

Structure of a tetratertiaryamino-diphenolato macrocyclic ligand

C 28 H 40 N 4 O 2 cristallise dans P2 1 /n avec a = 12,529, b = 13,068 et c = 15,815 A, β = 93,58 °; affinement jusqua R = 0,052. Ce macrocycle a une configuration asymetrique. Les groupes OH phenoliques sont lies par liaisons hydrogene intramoleculaires aux atomes N les plus proches.