Rupam Singh

Tetraazacyclohexadeca Macrocyclic Ligand as a Neutral Carrier in a Cr Ion-selective Electrode

A polystyrene-based membrane of 2,10-dimethyl-4,12-diphenyl-1,5,9,13-tetraazacyclohexadeca-1,4,9,12-tetraene macrocyclic ionophore was prepared and investigated as Cr(III)-selective electrode. The best performance was observed with the membrane having the polystyrene-ligand-dibutylphthalate-sodiumtetraphenyl borate composition 1:4:1:1 with a Nernstian slope of 19.0 mV per decade of concentration between pH 3.0 and 6.5. This electrode has been found to be chemically inert and of adequate stability with a response time of 20 s and was used over a period of 100 d with good reproducibility (S= 0.3 mV). The membrane works satisfactorily in a partially non-aqueous medium up to a maximum 30% (v/v) content of methanol and ethanol. The potentiometric selectivity coefficient values indicate that the membrane sensor is highly selective for Cr(III) ions over a number of monovalent, divalent and trivalent cations. The membrane electrode has also been successfully used to determine Cr3+ in various food materials.

New bis-macrocyclic complexes with transition metal ions

Template condensation of benzidine, formaldehyde, ethylenediamine or 1,3-diaminopropane, metal salt and 1-phenyl-1,3-butanedione or 2,3-butanedione in a 1:4:2:2 molar ratio results in the formation of two new series of binuclear pentaaza macrocyclic complexes: dichloro[1,1′-phenylbis(7-methyl-9-phenyl-1,3,6,10,13-pentaazacyclotetradeca-6,9-diene) metal(II)], [M2LCl4] (M = CoII, CuII, FeIII and ZnII) and dichloro[1,1′-phenylbis(8,9-dimethyl-1,3,7,10,14-pentaazacyclopentadeca-7,9-diene) metal(II)], [M2L′Cl4] (M = NiII, CoII, CuII and CdII). Both series were characterized by i.r., 1H-n.m.r., u.v.–vis. spectral studies, conductivity and magnetic susceptibility measurements.

Lead‐Selective Potentiometric Sensor Based on Macrocyclic Ionophore [Pyo2(16)Diene N6]

Abstract Polystyrene‐based membrane of 2,3,4:10,11,12‐dipyridine‐1,3,5,9,11,13‐hexaazacyclohexadeca‐2,10‐diene with sodium tetraphenyl borate (STB) and dibutyl phthalate (DBP) as anion excluder and plasticizing agent was prepared and investigated as Pb(II)‐selective electrode. The best performance was observed with the membrane having the polystyrene‐ligand‐DBP‐STB composition 1:6:1:1, worked well over a wide concentration range (1.41 × 10−6 to 1.00 × 10−1 mol L−1) with a Nernstian slope of 29.0 mV per decade of concentration between pH 3.0 and 6.0. The limit of detection is 1.0 × 10−6. This electrode has been found to be chemically inert and of adequate stability with a response time of 15 s and was used over a period of 100 d with good reproducibility (S = 0.3 mV). The membrane works satisfactorily in a partially nonaqueous medium up to a maximum 30% (v/v) content of methanol, ethanol, and acetone. The potentiometric selectivity coefficient values indicate that the membrane sensor is highly selective for Pb (II) ions over a number of monovalent, divalent, and trivalent cations. The practical ability of the membrane sensor has also been observed in solutions contaminated with detergents (i.e., cetyltrimethylammonium bromide and sodium dodecyl sulfate). The membrane electrode has also been successfully used to determine Pb2+ in real samples. Supported by the Council of Scientific and Industrial Research (CSIR), New Delhi, India.

STRONTIUM (II)-SELECTIVE ELECTRODE BASED ON A MACROCYCLIC LIGAND

A poly(vinyl chloride)-based membrane of 2,9-dimethyl-4,11-diphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,8,11-tetraene with sodium tetraphenylborate (STB) as an anion excluder and dibutyl phthalate (DBP), tris(2-ethylhexyl) phosphate (TEP), dibutyl butylphosphonate (DBBP), and tributyl phosphate (TBP) as plasticizing solvent mediators was prepared and investigated as a Sr(II)-selective electrode. The best performance was observed with the membrane having the ligand-PVC-DBP-STB composition 1:4 : 1:1, which worked well over a wide concentration range (1.4 × 10−6−0.1 mol L−1) with a Nernstian slope of 28.6 mV per decade of concentration between pH 4.0 and 10.0. This electrode showed a fast response time of 12 s and was used over a period of 100 d with good reproducibility (s= 0.3 mV). The selectivity coefficients for monovalent, divalent and trivalent cations indicate excellent selectivity of Sr(II) ions over a large number of cations including Ca(II) and Ba(II). Anions such as Cl− and SO4 2 do not interfere and the electrode also works satisfactorily in partially water-alcohol medium. The sensor has been used as an indicator electrode in the potentiometric titration of Sr(II) with EDTA. The practical utility of the membrane sensor has also been observed in solutions contaminated with detergents i.e., cetyltrimethylammonium bromide and sodium dodecyl sulfate.

A New PVC-Membrane Electrode Based on a Diazatetrathia (N2S4) Macrocyclic Ligand for Selective Determination of Silver Ion

Abstract A poly(vinyl chloride) based membrane based on neutral macrocyclic ionophore: 2,3,4:10,11,12-dipyridine-3,11-diaza-1,5,9,13-tetrathiacyclohexadeca-2,10-diene with sodium tetraphenyl borate (STB) as an anion excluder and dibutylphthalate (DBP) and dioctylphthalate (DOP) as plasticizing solvent mediator was prepared and investigated as a Ag(I)-selective electrode. The best performance was observed with the membrane having the ligand-PVC-DBP-STB composition 1:6:1:2, which worked well over a wide concentration range (3.98 × 10−6 mol L−1−1.00 × 10−1 mol L−1) with a Nernstian slope of 55.3 mV per decade of activity between pH 3.0–7.0. This electrode showed a fast response time of 15 s and was used over a period of three months with good reproducibility (S = 0.3 mV). The selectivity coefficient for mono-, di-, and trivalent cations indicate excellent selectivity for Ag(I) ions over a large number of cations. Anions such as and do not interfere and the electrode also works satisfactorily in a partially nonaqueous medium. The sensor has been used as an indicator electrode in the potentiometric titration of Ag(I) with Nal solution. It has also been used successfully for determination of Ag(I) in real samples.