Salicylate-selective electrodes based on AI(III) and Sn(IV) salophens

Spectrophotometric and Smartphone-Assisted Determination of Phenolic Compounds Using Crude Eggplant Extract

In order to develop a simple, reliable and low cost enzymatic method for the determination of phenolic compounds we studied polyphenol oxidase activity of crude eggplant (S. melongena) extract using 13 phenolic compounds. Catechol, caffeic and chlorogenic acids, and L-DOPA have been rapidly oxidized with the formation of colored products. Monophenolic compounds have been oxidized at a much slower speed. Ferulic acid, quercetin, rutin, and dihydroquercetin have been found to inhibit polyphenol oxidase activity of crude eggplant extract. The influence of pH, temperature, crude eggplant extract amount, and 3-methyl-2-benzothiazolinone hydrazone (MBTH) concentration on the oxidation of catechol, caffeic acid, chlorogenic acid, and L-DOPA has been investigated spectrophotometrically. Michaelis constants values decrease by a factor of 2 to 3 in the presence of MBTH. Spectrophotometric (cuvette and microplate variants) and smartphone-assisted procedures for phenolic compounds determination have been proposed. Average saturation values (HSV color model) of the images of the microplate wells have been chosen as the analytical signal for smartphone-assisted procedure. LOD values for catechol, caffeic acid, chlorogenic acid, and L-DOPA equaled 5.1, 6.3, 5.8 and 30.0 µM (cuvette procedure), 12.2, 13.2, 13.2 and 80.4 µM (microplate procedure), and 23.5, 26.4, 20.8 and 120.6 µM (smartphone procedure). All the variants have been successfully applied for fast (4-5 min) and simple TPC determination in plant derived products and L-DOPA determination in model biological fluids. The values found with smartphone procedure are in good agreement with both spectrophotometric procedures values and reference values. Using crude eggplant extract- mediated reactions combined with smartphone camera detection has allowed creating low-cost, reliable and environmentally friendly analytical method for the determination of phenolic compounds.

Silica-titania xerogel for solid phase spectrophotometric determination of salicylate and its derivatives in biological liquids and pharmaceuticals

BACKGROUND

Salicylic acid and its derivatives are widely used drugs with potential toxicity. The main areas of salicylate derivatives determination are biological liquids and pharmaceuticals analysis.

RESULTS

Silica-titania xerogel has been used for solid phase spectrophotometric determination of various salicylate derivatives (salicylate, salicylamide, methylsalicylate). The reaction conditions influence on the interaction of salicylate derivatives with silica-titania xerogels has been investigated; the characteristics of titanium(IV)-salicylate derivatives complexes in solid phase have been described. The simple solid phase spectrophotometric procedures are based on the formation of xerogel incorporated titanium(IV) colored complexes with salicylate derivatives. A linear response has been observed in the following concentration ranges 0.1-5, 0.5-10 and 0.05-4.7 mM for salicylate, salicylamide, and methylsalicylate, respectively. The proposed procedures have been applied to the analysis of human urine, synthetic serum, and pharmaceuticals.

CONCLUSIONS

The simple solid phase spectrophotometric procedures of salicylate derivatives determination based on the new sensor materials have been proposed for biological liquids and pharmaceuticals analysis. Graphical abstractComplexation of titanium (IV), incorporated in silica-titania xerogels (Si-Ti), with salicylate derivatives (L) resulting in yellow-colored xerogels (Si-Ti/Ln) has been proposed for salicylate derivatives determination in biological liquids and pharmaceuticals.

Direct observation of aluminium ions produced via pulsed laser ablation in liquid: a 'turn-on' fluorescence study

An Al metal plate was ablated by a pulsed Nd-YAG laser to produce nano-structured Al and gamma-Al(2)O(3) in deionized water without any surfactants or catalysts. In this study, direct evidence for the production of Al(3+) ions from the plasma plume is presented for the first time by characterizing the absorption and emission spectra of their [Al(salophen)](+) complex. Very interestingly, a remarkable increase in the fluorescence intensity was observed when the Al(3+) ions, produced via the pulsed laser ablation, complexed with the salophen ligand. This fluorescence 'turn-on' behaviour of [Al(salophen)](+) was investigated by DFT/TD-DFT calculations. Based on these results, mechanisms for the production of aluminium and alumina nanoparticles in the pulsed laser ablation in liquid (PLAL) process are proposed.

Application of metalloporphyrin grafted-graphene oxide for the construction of a novel salicylate-selective electrode

Due to the vast applications of salicylate ion, development of a simple and selective procedure for its determination is of practical interest. Herein, the unique properties of graphene oxide are combined with the anion selectivity of metalloporphyrins to construct a novel salicylate selective electrode. This electrode is prepared by incorporating Cu(II)–5-4 (aminophenyl)-10,15,20-triphenyl porphyrin grafted-grapheneoxide (CuTPP-GO) into the plasticized poly (vinyl chloride) membrane. Effects of plasticizer nature, Cu TPP-GO concentration and anionic and cationic additives on the potential response of the electrode are investigated. The electrode with the membrane composition of 25% PVC, 50% NPOE, 5% NaTPB and 20% Cu TPP-GO provided the best behavior. This sensor shows a Nernstian response (57.8 mV.decade-1) in the concentration range of 5.0 × 10-1–5.0 × 10-7M with detection limit of 8.0 × 10-8M. sensor response is stable in the pH range of 5–7 and shows a discriminating ability for salicylate compared to most common anions. The sensor was successfully used for determination of salicylate in an aspirin tablet.

Novel PVC-membrane potentiometric sensors based on a recently synthesized sulfur-containing macrocyclic diamide for Cd2+ ion. Application to flow-injection potentiometry

A new sulfur-containing macrocyclic diamide, 1,15-diaza-3,4,12,13-dibenzo-5,11-dithia-8-oxa-1,15-(2,6-pyrido)cyclooctadecan-2,14-dione, L, was synthesized, characterized and used as an active component for fabrication of PVC-based polymeric membrane (PME), coated graphite (CGE) and coated silver wire electrodes (CWE) for sensing Cd(2+) ion. The electrodes exhibited linear Nernstian responses to Cd(2+) ion in the concentration range of 3.3 x 10(-6) to 3.3 x 10(-1)M (for PME, LOD=1.2 x 10(-6)M), 2.0 x 10(-7) to 3.3 x 10(-1)M (for CWE, LOD=1.3 x 10(-7)M) and 1.6 x 10(-8) to 1.3 x 10(-1)M (for CGE, LOD=1.0 x 10(-8)M). The CGE was used as a proper detection system in flow-injection potentiometry (FIP) with a linear Nernstian range of 3.2 x 10(-8) to 1.4 x 10(-1)M (LOD=1.3 x 10(-8)M). The optimum pH range was 3.5-7.6. The electrodes revealed fairly good discriminating ability towards Cd(2+) in comparison with a large number of alkali, alkaline earth, transition and heavy metal ions. The electrodes found to be chemically inert, showing a fast response time of <5s, and could be used practically over a period of about 2-3 months. The practical utility of the proposed system has also been reported.

{6,6'-Dimeth-oxy-2,2'-[2,2-dimethyl-propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato}nickel(II) 1.78-hydrate

In the title complex, [Ni(C₂₁H₂₄N₂O₄)]·1.78H₂O, the Ni^II ion has a slightly distorted planar geometry, coordinated by the two N and two O atoms of the tetra­dentate Schiff base ligand, with a mean deviation of 0.272 Å from the NiN₂O₂ plane. The N and O donor atoms are mutually cis. The dihedral angle between two benzene rings of the ligand is 38.86 (8)°. There are also three solvent water mol­ecules, two of which lie across different crystallographic twofold rotation axes; one of these is partially occupied with a refined occupancy factor of 0.570 (7). The water mol­ecules are linked together as tetra­mers in R₂²(8) ring motifs, which also connect two neighbouring mol­ecules of the complex through a network of O—H⋯O hydrogen bonds. The crystal structure is further stabilized by inter­molecular C—H⋯O and C—H⋯π inter­actions, which link neighbouring mol­ecules into extended chains along the b axis. Other inter­esting features of the crystal structure are the short inter­molecular C⋯C [3.204 (3)–3.365 (3) Å] and the C⋯O [3.199 (2)–3.205 (2) Å] contacts which are shorter than the sum of the van der Waals radii of these atoms.

{6,6'-Dieth-oxy-2,2'-[2,2-dimethyl-propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato}copper(II) monohydrate

In the title complex, [Cu(C(23)H(28)N(2)O(4))]·H(2)O, the Cu(II) ion has a distorted planar geometry, coordinated by the N(2)O(2) unit of the tetra-dentate Schiff base ligand. The asymmetric unit comprises one complex mol-ecule and a water mol-ecule of crystallization. The water H atoms form bifurcated O-H⋯(O,O) inter-molecular hydrogen bonds with the O atoms of the phenolate and eth-oxy groups with R(1) (2)(5) and R(1) (2)(6) ring motifs, which may, in part, influence the mol-ecular configuration. The dihedral angle between the two O-Cu-N coordination planes is 31.02 (6)° and the dihedral angle between the two benzene rings is 34.98 (7)°. In the crystal structure, mol-ecules are linked together by inter-molecular C-H⋯O inter-actions, forming extended chains along the a axis. The crystal structure is further stabilized by inter-molecular C-H⋯π and π-π [centroid-centroid = 3.5068 (13) Å] inter-actions.

{6,6'-Diethoxy-2,2'-[4,5-dimethyl-o-phenylenebis(nitrilomethylidyne)]di-phenolato}nickel(II) dihydrate

In the title complex, [Ni(C₂₆H₂₆N₂O₄)]·2H₂O, the Ni^II ion, lying on a twofold crystallographic rotation axis, has a square-planar geometry, being coordinated by the N₂O₂ unit of the tetra­dentate Schiff base ligand. The asymmetric unit of the title compound comprises one-half of the complex mol­ecule and one of the water mol­ecules of crystallization. The water H atoms form bifurcated O—H⋯(O,O) hydrogen bonds with the O atoms of the phenolato and eth­oxy groups with R₁²(5) and R₁²(6) ring motifs. The dihedral angle between the central benzene ring and the two outer benzene rings are 4.07 (11) and 3.99 (12)°. The dihedral angle between the two O–Ni–N coordination planes is only 0.77 (11)°. In the crystal structure, the mol­ecules are linked together into extended chains along the c axis by inter­molecular O—H⋯O and C—H⋯O inter­actions. An inter­esting feature of the crystal structure is a short inter­molecular C ⋯ C [3.355 (3) Å] contact, which is shorter than the sum of the van der Waals radii. The crystal structure may be further stabilized by inter­molecular π–π inter­actions [centroid–centroid distances in the range 3.5758 (13)–3.6337 (13) Å].

{6,6'-Dieth-oxy-2,2'-[2,2-dimethyl-propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato}nickel(II) monohydrate

In the title complex, [Ni(C(23)H(28)N(2)O(4))]·H(2)O, the Ni(II) ion is coordinated by the N(2)O(2) unit of the tetra-dentate Schiff base ligand in a slightly distorted planar geometry. The asymmetric unit of the title compound comprises one complex mol-ecule and a water mol-ecule of crystallization. The H atoms of the water mol-ecule make bifurcated inter-molecular hydrogen bonds with the O atoms of the phenolate and eth-oxy groups with R(1) (2)(5) and R(1) (2)(6) ring motifs, which may, in part, influence the mol-ecular configuration. The dihedral angle between the two benzene rings is 31.43 (5)°. The crystal structure is further stabilized by inter-molecular C-H⋯O and C-H⋯π inter-actions, which link neighbouring mol-ecules into one-dimensional extended chains along the a axis. An inter-esting feature of the crystal structure is the short inter-molecular C⋯C [3.3044 (14) Å] contact which is shorter than the sum of the van der Waals radii.

6,6'-Dieth-oxy-2,2'-[4,5-dimethyl-o-phenyl-enebis(nitrilo-methyl-idyne)]diphenol-ethanol-water (1/1/1)

The title bis-Schiff base compound, C₂₆H₂₈N₂O₄·C₂H₆O·H₂O, crystallizes as an ethanol and water solvate. Strong intra­molecular O—H⋯N hydrogen bonds generate S(6) ring motifs. The water H atoms form bifurcated O—H⋯(O,O) inter­molecular hydrogen bonds with the O atoms of the hydroxyl and eth­oxy groups with R₁²(5) ring motifs, which may, in part, influence the mol­ecular configuration. The dihedral angles between the central benzene ring and the two outer benzene rings of the Schiff base mol­ecule are 5.64 (8) and 44.78 (9)°. The crystal structure is further stabilized by inter­molecular C—H⋯O and π–π inter­actions [centroid–centroid distances = 3.6139 (11)–3.7993 (11) Å].

{4,4'-Dibromo-2,2'-[2,2-dimethyl-propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato-κO,N,N',O'}copper(II)

In the title compound, [Cu(C₁₉H₁₈Br₂N₂O₂)], the Cu^II ion is in a tetra­hedrally distorted planar geometry, involving two N and two O atoms from the tetra­dentate Schiff base ligand. Inter­molecular C—H⋯O hydrogen bonds form an eight-membered R₂²(8) motif. The dihedral angle betwen two benzene rings is 36.34 (9)°. There are inter­molecular Cu⋯Br [3.4566 (5) Å] and Cu⋯·N [3.569 (3) Å] contacts, which are significantly shorter than the sum of van der Waals radii of the relevant atoms. These inter­actions, along with the inter­molecular C—H⋯π and π–π [centroid–centroid distances of 3.709 (1) and 3.968 (2) Å] inter­actions, link neighbouring mol­ecules into a one-dimensional infinite chain along the c axis.

(Z)-6-{2-[(E)-2,4-Dihydroxy-benzyl-ideneamino]phenyl-amino-methyl-ene}-3-hydroxy-cyclo-hexa-2,4-dienone toluene solvate

The bis-Schiff base title compound, C(20)H(16)N(2)O(4)·C(7)H(8), crystallized as a toluene solvate. In the solid state, it is present as its prototropic tautomer formed by transfer of one of the ortho-hydroxyl H atoms. The proton transfer is accompanied by a shift of electron pairs, as is evident from the observed C-O and C-N bond distances of 1.305 (2) and 1.315 (2) Å, which are largely consistent with C=O and C-N distances. The actual mol-ecule present in the solid state is thus the charge-neutral β-keto amine, with a small contribution of its zwitterionic valence tautomer via partial delocalization of electron pairs along the N-C-C-C-O atom chain. The dihedral angles between the central benzene ring and the two outer benzene rings of the Schiff base are 51.99 (8) and 12.95 (9)°. Intra-molecular O-H⋯N and N-H⋯O hydrogen bonds generate S(6) ring motifs, whereas intra-molecular N-H⋯N hydrogen bonds generate S(5) ring motifs. In the crystal structure, O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions link the mol-ecules into one-dimensional zigzag chains along the b axis; these chains are further stacked by O-H⋯O and weak C-H⋯O inter-actions along the c axis, forming two-dimensional extended networks parallel to the bc plane. In addition, the crystal structure is further stabilized by weak C-H⋯π and π-π inter-actions.

{5,5'-Dihydr-oxy-2,2'-[o-phenyl-enebis-(nitrilo-methyl-idyne)]diphenolato}nickel(II) dihydrate

In the title complex, [Ni(C(20)H(14)N(2)O(4))]·2H(2)O, the Ni(II) ion is in an essentially square-planar geometry involving an N(2)O(2) atom set of the tetra-dentate Schiff base ligand. The Ni atom lies on a crystallographic twofold rotation axis. The asymmetric unit contains one half-mol-ecule of the complex and a water mol-ecule. An inter-molecular O-H⋯O hydrogen bond forms a four-membered ring, producing an R(1) (2)(4) ring motif involving a bifurcated hydrogen bond to the phenolate O atoms of the complex mol-ecule. In the crystal structure, mol-ecules are linked by π-π stacking inter-actions, with centroid-centroid distances in the range 3.5750 (11)-3.7750 (11) Å. As a result of the twofold symmetry, the central benzene ring makes the same dihedral angle of 15.75 (9)° with the two outer benzene rings. The dihedral angle between the two hydroxy-phenyl rings is 13.16 (5)°. In the crystal structure, mol-ecules are linked into infinite one-dimensional chains by directed four-membered O-H⋯O-H inter-actions along the c axis and are further connected by C-H⋯O and π-π stacking into a three-dimensional network. An inter-esting feature of the crystal structure is the short Ni⋯O, O⋯O and N⋯N inter-actions which are shorter than the sum of the van der Waals radii of the relevant atoms. The crystal structure is stabilized by inter-molecular O-H⋯O and C-H⋯O hydrogen bonds and by π-π stacking inter-actions.

2-[(E)-(5-Amino-2,3-diphenylquinoxalin-6-yl)iminomethyl]-4-chlorophenol

The title Schiff base compound, C₂₇H₁₉ClN₄O, features two intra­molecular O—H⋯N and N—H⋯N hydrogen bonds involving the hydr­oxy and amino groups to generate S(6) and S(5) ring motifs, respectively. In the crystal structure, weak inter­molecular N—H⋯O and C—H⋯N inter­actions, together with π–π contacts [centroid–centroid distances = 3.6294 (11)–3.6881 (11) Å], link neighboring mol­ecules.

{4,4',5,5'-Tetra-methyl-2,2'-[1,1'-(ethane-1,2-diyldinitrilo)diethyl-idyne]diphenolato}nickel(II)-methanol-chloro-form (1/1/1)

In the title compound, [Ni(C(22)H(26)N(2)O(2))]·CH(3)OH·CHCl(3), the Ni(II) ion is in a slightly distorted square-planar geometry involving an N(2)O(2) atom set of the tetra-dentate Schiff base ligand. The asymmetric unit contains one mol-ecule of the complex and one mol-ecule each of chloro-form and methanol. The methanol mol-ecule is hydrogen bonded to the phenolate O atoms. In the crystal structure, short inter-molecular distances between the centroids of six-membered chelate rings [3.7002 (9) Å] indicate the presence of π-π inter-actions, which link the mol-ecules into stacks along the a axis. In addition, there are Ni⋯Ni distances which are shorter than the sum of the van der Waals radii of two Ni atoms. The crystal structure is further stabilized by inter-molecular O-H⋯O and C-H⋯O hydrogen bonds, and weak inter-molecular C-H⋯π inter-actions linking mol-ecules into extended one-dimensional chains along the c axis.

{4,4'-Dimeth-oxy-2,2'-[1,1'-(ethane-1,2-diyldinitrilo)diethyl-idyne]diphenolato}nickel(II) hemihydrate

In the title complex, [Ni(C₂₀H₂₂N₂O₄)]·0.5H₂O, the Ni^II ion is in a slightly distorted square-planar geometry involving an N₂O₂ atom set of the tetra­dentate Schiff base ligand. The asymmetric unit contains one mol­ecule of the complex and half a water solvent mol­ecule. The solvent water mol­ecule lies on a crystallographic twofold rotation axis. An inter­molecular O—H⋯O hydrogen bond forms an R₂¹(4) ring motif involving a bifurcated hydrogen bond to the phenolate O atoms of the complex. In the crystal structure, mol­ecules are linked by π–π stacking inter­actions, with centroid–centroid distances in the range 3.5310 (11)–3.7905 (12) Å, forming extended chains along the b axis. In addition, there are Ni⋯Ni and Ni⋯N inter­actions [3.4404 (4)–4.1588 (4) and 3.383 (2)–3.756 (2) Å, respectively] which are shorter than the sum of the van der Waals radii of the relevant atoms. Further stabilization of the crystal structure is attained by weak inter­molecular C—H⋯O and C—H⋯π inter­actions.

2-[(E)-(5-Amino-2,3-diphenyl-quinoxalin-6-yl)imino-meth-yl]-4-bromo-phenol

The title compound, C(27)H(19)BrN(4)O, is a mono-anil Schiff base ligand. Three intra-molecular O-H⋯N and N-H⋯N hydrogen bonds involving the hydr-oxy and amino groups generate S(6) and S(5) ring motifs, respectively. In the crystal structure, weak inter-molecular N-H⋯O and C-H⋯O hydrogen bonds together with π-π inter-actions [centroid-centroid distances = 3.628 (3)-3.729 (3) Å] link neighboring mol-ecules.

Potentiometric response and mechanism of anionic recognition of heterocalixarene-based ion selective electrodes

The ion selective electrode (ISE)-based potentiometric approach is shown to be an effective means of characterizing the anion recognition sites in the molecular receptor calix[2]pyridino[2]pyrrole (CPP). In particular, potentiometric pH-measurements involving the use of experimental PVC-membranes based on CPP revealed the existence of both mono- and diprotonated forms of the receptor under readily accessible conditions. Based on these analyses, apparent surface protonation constants for this heterocalixarene were found to lie between 8.5-8.9 (pK(B1)) and 3.3-3.8 (pK(B2)). CPP was found to interact with targeted anionic analytes based on both coulombic and hydrogen bond interactions, as inferred from varying the kinds of ionic sites present within the membrane phase. Potentiometric selectivity studies revealed that CPP preferred "Y-shaped" anions (e.g. acetate, lactate, benzoate) over spherical anions (e.g. fluoride and chloride), fluoride over chloride within the set of spherical anions, and the ortho-isomer over the corresponding meta- and para-isomers in the case of hydroxybenzoate (salicylate and congeners). In the context of this study, the advantages of potentiometric determinations of acetylsalicylic acid using optimized PVC-membranes based on CPP relative to more conventional PVC-membrane ISEs based on traditional anion exchanger were also demonstrated.

Potentiometric anion selectivity of polymer-membrane electrodes based on cobalt, chromium, and aluminum salens

Metallo-salens of cobalt(II) (Co-Sal), chromium(III) (Cr-Sal), and aluminum(III) (Al-Sal) are used as the active ionophores within plasticized poly(vinyl chloride) membranes. It is shown that central metal-ion plays a critical role in directing the ionophore selectivity. Polymer-membrane electrodes based on Co-Sal, Cr-Sal, and Al-Sal are demonstrated to exhibit enhanced responses and selectivity toward nitrite/thiocyanate, thiocyanate, and fluoride anions, respectively. The improved anion selectivity of the three ionophore systems is shown to deviate significantly from the classical Hofmeister pattern that is based only on ion lipophilicity. For example, optimized membrane electrodes for nitrite ion based on Co-Sal exhibit logK(Nitrite,Anion)(pot) values of -5.22, -4.66, -4.48, -2.5 towards bromide, perchlorate, nitrate, and iodide anions, respectively. Optimized membrane electrodes based on Co-Sal and Cr-Sal show near-Nernstian responses towards nitrite (-57.9+/-0.9 mV/decade) and thiocyanate (-56.9+/-0.8 mV/decade), respectively, with fast response and recovery times. In contrast, Al-Sal based membrane electrodes respond to fluoride ion in a super-Nernstian (-70+/-3 mV/decade) and nearly an irreversible mode. The operative response mechanism of Co-Sal, Cr-Sal, and Al-Sal membrane electrodes is examined using the effect of added ionic sites on the potentiometric response characteristics. It is demonstrated that addition of lipophilic anionic sites to membrane electrodes based on the utilized metallo-salens enhances the selectivity towards the primary ion, while addition of cationic sites resulted in Hofmeister selectivity patterns suggesting that the operative response mechanism is of the charged carrier type. Electron spin resonance (ESR) data indicates that Co(II) metal-ion center of Co-Sal ionophore undergoes oxidation to Co(III). This process leads to formation of a charged anion-carrier that is consistent with the response behavior obtained for Co-Sal based membrane electrodes.

A novel thiocyanate-selective electrode based on a zinc–phthalocyanine complex

A novel thiocyanate (SCN-)-selective PVC membrane electrode based on a zinc-phthalocyanine (ZnPc) complex as neutral carrier is described. The membrane electrode containing ZnPc with 5.1% (w/w) ionophore, 29.2% (w/w) PVC, and 65.7% (w/w) 2-nitrophenyl octyl ether (o-NPOE) as plasticizer displayed an anti-Hofmeister selectivity sequence, SCN- > Sal- > I- > ClO4- > Br- > Cl- > NO3- > NO2- > H2PO4- > SO4(2-)), and exhibited near-Nernstian potential response to thiocyanate ranging from about 1.0 x 10(-1) to 1.0 x 10(-6) mol L(-1) with a detection limit of 7.5 x 10(-7) mol L(-1) and a slope of 58.1+/-0.5 mV per decade in pH 3.0 phosphate buffer solution at 25 degrees C. This preferential response is believed to be associated with the unique coordination between the central metal of the carrier and thiocyanate.

Highly Selective Iodide Electrode Based on the Copper(II)-N,N′-bis(salicylidene)-1,2-bis(p-aminophenoxy)ethane Tetradentate Complex

In this paper, a new PVC-based liquid-membrane anion-selective electrode based on a copper(II) of N,N'-bis(salicylidene)-1,2-bis(p-aminophenoxy)ethane tetradentate complex (Cu(II)BBAP) is described, which displays a preferential potentiometric response to iodide ion at pH 2.0 and an anti-Hofmeister selectivity sequence: I->SCN->ClO4->NO2->H2PO4->NO3->SO4(2-)>Br->Cl-. The electrode exhibits a near-Nernstian potential linear range of 8.2x10(-7)-1.0x10(-1) M with a detection limit of 5.3x10(-7) M and a slope of -58.8 mV per decade. The A.C. impedance technique and the UV/Vis spectroscopy technique were used to analyze the response mechanism. The electrode could be applied to determine iodide in medicine analysis, and the obtained results were fairly satisfactory.