Solid Chelates Research Articles

Synthesis and characterization of new 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol (MMTP) Schiff base for spectrophotometric detection of iron(III) and copper(II) ions in laboratory and different water samples: A biological and molecular docking exploration

New spectrophotometric techniques were introduced for the determination of Fe(III) and Cu(II) in many different analyzed samples. The concentrations of Fe(III) and Cu(II) ions were measured in the existence of a novel Schiff base (Z)-6-(3-mercapto-5-methyl-4H-1,2,4-triazol-4-ylimino)-2-thioxotetrahydropyrimidin-4(1H)-one (MMTP). The new chelates were formed rapidly at the room temperature at 510 and 550 nm in presence of triton X-100 and CPB surfactants for Fe(III) and Cu(II), respectively. Linear calibrated graphs were obtained at concentration ranges of 1.0–130 µg mL-1 for Fe(III) and 0.5–90 µg mL-1 for Cu(II). LOD were calculated to be 1.05, 1.98 µg mL-1 and LOQ were 3.18 and 6.02 µg mL-1 for Fe(III) and Cu(II), respectively. A large number of foreign ions were not interfering in the present method. The stoichiometric composition of the chelates was studied by molar ratio and job´s methods to be found 1:2 (metal ion: ligand) ratio. The Fe(III) and Cu(II) solid chelates were prepared and characterized using IR, UV–Vis., 1HNMR , 13CNMR TG-DTG, and XRD spectroscopy. The IR spectral revealed that MMTP chelated as a bidentate ligand via NO atoms. Thermal analysis revealed the decomposition mechanism of MMTP and its chelates. A suggested octahedral geometry encompasses all of the chelates. The UV–visible spectra and magnetic moment analyses confirm the octahedral geometrical geometries. The band gap (Eg) values are 1.53 and 1.56 for Fe(III) and Cu(II) respectively. The smallest band gaps imply that these chelates are semiconductors belonging to solar materials. The in-vitro antioxidant activity of the individual chelates was evaluated using the DPPH radical scavenging assay. All compounds showed antioxidant activity with IC50 values of 0.316, 0.186 and 0.124 mg/mL for MMTP, Fe(III) and Cu(II), respectively. MMTP and its chelates were tested for their antimicrobial activity against various types of bacteria and fungi using the disc diffusion method. The Cu(II) complex showed the greatest biological activity.

Design, synthesize, physicochemical characterization, nonlinear optical properties structural elucidation, biomedical studies, and DNA interaction of some new mixed ligand complexes incorporating 4,6‐dimethylpyrimidine derivative and imidazole ligand

This study was planned to prepare new mixed ligand chelates derived from N‐(4,6‐dimethylpyrimidin‐2‐yl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐benzimidazol‐2‐amine (BIP), and imidazole (I). They identified through CHN study, spectroscopic (NMR, FT‐IR, and UV–Vis), conductivity, magnetic susceptibility, mass analysis, and thermal analysis. Correlation between all results exposed that the BIP ligand performed as a bi‐dentate ligand through NN donation locations, where the co‐ligand shows as N–H monodentate. The optimization for the studied chelates led to the formation of distorted octahedral geometry for BIPICu and BIPIVO chelates, distorted (tetrahedral and square planar) geometry for BIPIAg and BIPIPd chelates, respectively, around the metal salt. The B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6–311G**‐LANL2DZ functional level for the solid chelates were used in density functional theory (DFT) calculations. The findings showed that DFT calculations produce conclusions that are consistent with those of the experiments. The resulting compounds' nonlinear optical properties were examined by calculating the hyperpolarizability (β) and molecular polarizability (α) parameters, which gave rise to several unexpected optical properties for the synthesized compounds. Using the agar well diffusion method, the antimicrobial activity of the produced compounds was experimentally confirmed against a subset of G+ and G− bacteria. To ascertain how these substances attach to the targeted protein binding sites, a molecular docking mechanism between the microbially resistant chelates and their suppressed microbial protein pocket receptors was investigated. Also, DNA binding estimated for studied structures was tested by electronic absorption spectrum, viscosity estimation, and gel electrophoresis. Data proposed that all tested compounds link with DNA using an intercalation, electrostatic, and covalent binding mechanism. Moreover, antioxidant performance for studied compounds was governed by radical scavenging techniques in vitro. In addition, an MTT assay has been worked out to explore in vitro cytotoxic impending. All the tested chelates assumed antimicrobial, antitumor, and antioxidant performances that cause them to suggest drugs.

Green processing and characterization of Novel HETERO-ligand Co(II) complexes with cyanopyridine derivatives: Quantitative structure, Computational assessment, and Biological activity relationship

Novel hetero-ligand Co(II) complexes prepared from mixed ligand of ammonium metavanadate and cyanopyridine derivatives as a polydentate ligands by an easy and green ball milling technique to limit the use of hazardous compounds in the preparation process. The isolated solid chelates were demonstrated via various spectroscopic techniques including (13C NMR, 1H NMR, UV-visible, IR, SEM, XRD, and EXD), thermal analyses (TG, DTG), and elemental analyses. Also, the optimized structure for the isolated solid compounds were supported by applying DFT theory along with the calculations of altered energetic parameters for instance EHOMO and ELUMO. Moreover, the optimized target isolated solid compounds were proposed to be used for docking and were ordered using the defaulting methodology of the Ligprep software in Schrödinger's suite. Whereas, the three-dimensional complex structures of E. coli (PDB code: 1 xk6), S. aureus (PDB code: 6 gyw), C. albicans (PDB code: 3 ppc) and Covid 19 virus (PDB code: 7 jpy) were regained from the Protein Data Bank. Lastly, Bleomycin dependent DNA damage, antioxidant, and anti-microbia were performed for all isolated solid compounds to invistigate the impact of complexation on the biological activity of cyanopyridine derivatives.

Comparison on biological inspection, optimization, cyclic voltammetry, and molecular docking evaluation of novel bivalent transition metal chelates of Schiff Base pincer ligand

The presented work introduces a comprehensive study of the ligation behavior of the Schiff base ligand N-3-phenylallylidene nicotinohydrazide HNP toward transition metal cations, VO(II), Cu(II), and Cd(II), to synthesize novel solid chelates and examine their biological potencies. The ligand and its chelates were structurally elucidated using a diverse array of spectroscopic techniques, including FT-IR, UV–visible, 1H/13C NMR, ESR, PXRD, SEM, EDX, and LC/GCMS, besides thermal analysis TG/DTA, magnetic measurements, conductivity measurements, and elemental analysis. The comparison between the FT-IR spectra of both the ligand and its chelates revealed that HNP coordinated as a neutral bidentate with VO(II) and Cd(II) ions, while it coordinated as a mono-negative bidentate with the Cu(II) ion. The electronic absorption spectra depicted absorption bands at 19342 and 14925 cm−1 for the VO(II) and Cu(II) complexes, respectively, predicting square pyramidal and square planner arrangements. The cyclic voltammetry technique was used to study the electrochemical behavior of the Cu(II) ion in the absence/presence of HNP, whereas the chelation process in solution occurred spontaneously. Computational studies were applied using the Gaussian 09 program on the molecular structure of the isolated compounds based on the DFT/LAN2DZ/RB3LYP method to assess some chemical quantum parameters and perform correlation analyses between the theoretical and experimental FT-IR spectra. The values of R2 ranged from 0.99 to one, revealing a strong correlation between the theoretical and experimental data. Furthermore, molecular docking studies of the prepared compounds with the target proteins were performed using the MOE program. The docking results suggested that the VO(II) complex tended to be a biologically effective compound, wherein the VO(II) complex recorded inhibition grades of -6.16, -6.95, and -6.38 kcal/mol toward the target proteins and RMSD values of 0.92, 0.85, and 0.88 Å. Finally, the ligand and its complexes were screened for various biological assays, which highlighted the biological activity of the VO(II) complex. The VO(II) complex ranked as the highest antimicrobial with activity index values of 37.5, 59.1, and 26.9% against E. coli, Bacillus subtilis, and C. albicans, respectively. In addition, the VO(II) complex ranked as the highest antioxidant with an IC50 value of 63.09 μM and the highest capacity for DNA binding with an IC50 value of 43.8 μM. Furthermore, the VO(II) complex exhibited the highest cytotoxicity with IC50 values of 26.8, 21.8, and 32.4 μM against HePG-2, MCf-7, and Hela cell lines, respectively. Accordingly, this comprehensive study provides insight into the possible uses of these innovative chelates as potential therapeutics and enhances our comprehension of their molecular interactions and biological effectiveness.

Novel 1,3‐diphenyl‐4‐(N,N‐dimethylimido dicarbonimidic diamide azo)‐5‐pyrazolone and its chelates with manganese, nickel, copper, and zinc divalent metal ions as an antibacterial activity supported by molecular docking studies: Design, synthesis, DFT, and TD‐DFT/PCM calculations

A novel 1,3‐diphenyl‐4‐(N,N‐dimethylimidodicarbonimidic diamide azo)‐5‐pyrazolone as a ligand, simplified as DNP, and its chelates were prepared. Characterization of the structures was performed based on several analytical and spectroscopic techniques. To support these studies, density functional theory (DFT) calculations were carried out by using the B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6‐311G**‐LANL2DZ functional level for the solid chelates. The acquired results indicated that DFT calculations generally give compatible results with the experimental ones. Hyper conjugative interactions, molecular stability, bond strength, and intramolecular charge transfer were examined by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of the obtained compounds were investigated by determining molecular polarizability (α), and hyperpolarizability (β) parameters provided a hint for the synthesized compounds' intriguing optical characteristics. The electronic structure of the ligand and its complexes were predicted using the time‐dependent DFT (TD‐DFT) method with a polarizable continuum model (PCM) exploiting the B3LYP approach combined with a 6‐31G(d,p) basis set. The prepared compounds' antibacterial activity was experimentally verified utilizing the agar well diffusion method versus selected G + and G‐ bacteria. The molecular docking mechanism between the bacterially resistant chelates and their inhibited bacteria protein pocket receptors was carried out to determine the modes that these compounds bind to the protein's active sites.

Bivalent transition metal complexes of pyridine-2,6-dicarbohydrazide: Structural characterization, cyclic voltammetry and biological studies

A series of Co2+, Cu2+ and Cd2+ solid chelates are prepared from pyridine-2,6-dicarbohydrazide (H2P). All compounds are elucidated by spectroscopic and microscopic techniques (IR, UV–visible, 1HNMR, 13C NMR, ESR, XRD, MS spectra, SEM and EDX). In addition, they are investigated by elemental, magnetic and thermal (TG/DTA) analyses. The Gaussian 09 program has been employed to build up the best molecular structure for all the complexes based on the DFT method. The impact of complex formation at the electrochemical conduct of the Cd2+ cation has been investigated using cyclic voltammetry in absence/presence of H2P. Finally, biological investigations involving antimicrobial, antioxidant, erythrocyte hemolysis, DNA-binding and cytotoxicityare screened for all samples.

Synthesis, Characterization, Antibacterial, and Antifungal Activities of Cobalt(II), Nickel(II) and Copper(II) Complexes with 3-thioacetyl-2-amino-1,4-naphthoquinone and 2-benzoyl-3-amino-1,4-naphthoquinone Ligands

The aim of this work is to synthesize, characterize and evaluate the biological activity of 1,4-naphthoquinone derivatives ligands and their metal—Co(II), Ni(II) and Cu(II) chelates. Continuing our work with another derivatives of 1,4-naphthoquinone ligands, this work had been constructed for synthesis of new ligands derived from 1,4-naphthoquinone such as 3-thioacetyl-2-amino-1,4-naphthoquinone and 2-benzoyl-3-amino-1,4-naphthoquinone (L1-L2) which characterized on the basis of elemental analysis, electronic, IR, mass, 1H-NMR spectral data. The synthesized ligands have been carried out to achieve the coordination behavior towards bi-valent metal ions like cobalt, nickel and copper. The solid chelates of the different ligands were prepared and subjected to analytical techniques such as elemental analyses, spectroscopic techniques including mass, 1H-NMR, and IR spectroscopy, and thermal analyses techniques. The chelates were found to have octahedral geometry. The biological activity of the prepared ligands and their binary metals complexes were also screened against different antifungal and antibacterial organisms.

Synthesis and antimicrobial activities of Co (II), Ni (II) and Cu (II) complexes with N–S donor ligand

Aim: The extreme efforts have been developed to design novel compounds to strains of resistant micro-organisms. On-going search for novel and amazing drug delivery systems is primarily impact of the well-established fact that the convectional dosages are not sufficiently effective in conveying the drug compounds to its site of action and this has required the need to search for more efficient drugs. The metal complexes of Co (II), Ni (II) and Cu (II) with a tridentate ligand 2, 5-diamino-1, 3, 4-thiadiazole has been prepared by cyclisation of bithiourea in a 3% hydrogen peroxide medium. 2, 5-diamino-1, 3, 4-thiadiazole acts as neutral tridentate ligand and coordinates through the sulphur atom and nitrogen of the amines. The complexes are non-electrolyte in DMF. The complexes exhibited octahedral geometry. The antimicrobial activities of ligand and its complexes were screened using sensitivity test, minimum inhibition concentration and minimum bacterial concentration method. Metal chelates showed greater antimicrobial activities as compared to the control and the ligand. The metal chelates and the ligand did not exhibited activity against Aspergillus niger and Penicillin species. Methods: Elemental analyses, IR spectra, magnetic susceptibilities by using Faraday Balance, molar conductance by using Genway 4200 conductivity meter. Metal estimation by using Alpha 4 Atomic Absorption Spectrophotometer. Thin layer chromatography was carried out using TLC plate coated with silica gel. Results: The results of the elemental analyses are in good agreement with those calculated for the suggested formulae, 1:2 (M:L) solid chelates are isolated and found to have the general formulae [(ML2)] X2; M¼Co (II), Ni (II) and Cu (II) (X¼Cl). The IR spectra revealed that the ligand L is a neutral tridentate ligand. It coordinated to the metal ions via the nitrogen of the amines and sulphur atom. The molar conductance values of the Co (II), Ni (II), and Cu (II) complexes were relatively low, indicating the non-electrolytic nature of these complexes. The ligand and metal complexes show antimicrobial effect against the tested organism species except against molds of penicillin and Aspergillus. Niesseria gonorrhoea was probably the most sensitive organism to the 2, 5-Diamino-1, 3, 4-Thiadizole and its metal complexes. Metal complexes showed greater activity against some of the micro-organisms compared to the parent compounds.

Synthesis and characterization of bisaldehyde ligand with some transition metals and its application in spectrophotometric determination of Fe(III) in natural water samples using recovery test

Article history: Received 20 November 2011 Accepted 05 February 2012 The coordination behaviour of the bisaldehyde organic ligand with different coordination sites are investigated, towards some biand trivalent metal ions like Cr(III), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II). The solid chelates of the bisaldehyde are prepared and subjected to many analytical techniques such as elemental analyses, IR, 1 H NMR and solid reflectance spectra, magnetic moment, molar conductance, X-Ray diffraction (XRD) and thermal analyses. The chelates have octahedral geometry. The bisaldehyde ligand and its binary chelates were subjected to thermal analyses and the different activation thermodynamic parameters were calculated from their corresponding DTG curves. The biological activity of the bisaldehyde ligand and its complexes were also screened. The bisaldehyde ligand is utilized for spectrophotometric determination of spiked Fe(III) in natural water samples using recovery test under optimal experimental conditions.

Polymer complexes. LIV. Structural and spectral studies of supramolecular coordination polymers built from Ni(II), Fe(II) and Pd(II) with sulphadrug

Polymer complexes of p-acrylamidyl sulphaguanidine (HL) with Ni(II), Fe(II) and Pd(II) salts have been prepared. The structures of the polymer complexes were elucidated using elemental analysis, 1H NMR, UV–Vis, IR spectroscopies, magnetic moment, molar conductance and thermal analysis. The polymer complexes were isolated in 1:1 and 1:2 (M:L) ratios. The solid monocomplexes (1:1) (M:L) were isolated in the general formula [Fe(HL)O 2SO 2(OH 2) 2]. The biscomplexes (1:2) (M:L) solid chelates found to have the general formula [Ni(HL) 2X 2] n (X = Cl −, Br −, I −, NO 3 - , NCS −), [Fe(HL)(en)(OSO 3)(OH 2)] n and [Ni(HL) 2(Py) 2] n X 2, while {[Pd(L)X] 2} n (1:1) (X = Cl − or Br −). In all the polymer complexes the ligand and anions were found to be coordinated to the Ni(II) and Fe(II) ions. The bidentate nature of the ligand is evident from IR spectra. The magnetic and spectroscopic data indicate a octahedral geometry for complexes. The thermal behaviour of these chelates shows that the hydrated complexes loss water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps.

Metal chelates of ampicillin versus amoxicillin: synthesis, structural investigation, and biological studies

Solid chelates derived from some alkaline earth and transition metal complexes with ampicillin (Hamp, a) and amoxicillin (Hamox, b) were synthesized and characterized using elemental analysis, molar conductivity, IR, magnetic susceptibility, and thermogravimetric studies. Both drugs behave as tetradentate ligands coordinating to metal through amino, imino, and carboxylate as well as through β-lactamic carbonyl. All chelates have octahedral geometry except Cu(II) complexes which have square planar structure and uranium has pentagonal bipyramidal coordination. 1H- and 13C-NMR of the Zn(II) and UO2(VI) chelates are compared with the free ligands. The antimicrobial activity of the prepared chelates was determined.

Synthesis and characterization of Co(II), Ni(II) and Cu(II) complexes involving hydroxy antipyrine azodyes

The complexes formed between some hydroxy antipyrine azodyes and Co(II), Ni(II) and Cu(II) ions were studied spectrophotometrically in solution. The stoichiometry and stability constants of the metal chelates were determined. The spectrophotometric determination of the titled metal ions and titration using EDTA were reported. The chelating behaviour of the azodyes was confirmed by preparing the solid chelates in which their structures are elucidated using molar conductance, elemental, thermogravimetric (TGA) analyses, IR, ESR and electronic spectra as well as the magnetic measurements. Kinetic parameters are computed from the thermal decomposition data. The electrical properties for the metal complexes are measured from which the activation energies are calculated.

Structural and thermal characterization of cerium, thorium and uranyl complexes of sulfasalazine

Cerium(IV), Thorium(IV) and Uranyl(II) complexes with the ammonium salt of sulfasalazine drug (H 2SSZ, HL −) have been studied. The structures of the complexes were elucidated using elemental analysis, IR and mass spectroscopy and thermal analysis. The complexes were isolated in 1:1 and 1:2 (M:L) ratios. The solid monocomplexes (1:1) (M:H 2SSZ) were isolated in the general formulae [UO 2(L)(H 2O) 2]·2H 2O and [M(L)(X) z (H 2O) n ]· yH 2O (M = Ce(IV) and Th(IV) (X = NO 3, z = 2, n = 2, y = 0–3)). The biscomplexes (1:2) (M:H 2SSZ) solid chelates found to have the general formulae [UO 2(HL) 2]·2H 2O and [M(L) 2(H 2O) 2] (M = Ce(IV) and Th(IV)). The thermal decomposition of the complexes should be discussed in relation to structure, and the thermodynamic parameters of the decomposition stages were evaluated applying Coats–Redfern and Horwitz–Mitzger methods.

Chelation behaviour of nitroso- pyrazolones with Mn(II), Co(II), Ni(II), Cu(II) AND Zn(II)

Infrared (IR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TG), derivative thermogravimetric analysis (DTG), differential thermal analysis (DTA) and molar conductivity studies have been carried out on the chelates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3-methyl- and 3-phenyl-4-nitroso-5-pyrazolones. The solid chelates were synthesized, separated, analyzed and their structures were elucidated. The data obtained show that almost all of the prepared chelates contain water molecules in their coordination sphere. The initial stage in the thermal decomposition process of these chelates shows the presence of water molecule, the second denotes to the intermediate products. The final decomposition products were found to be the respective metal oxides. The NMR spectrum of 3-methyl-4-nitroso-5-pyrazolone ligand shows the existence of the oxime rather than the nitroso form. 3-phenyl-4-nitroso-5-pyrazolone acts as a neutral bidentate ligand whereas 3-methyl-4-nitroso-5-pyrazolone acts as monobasic bidentate ligand bonded to the metal ions through the two oxygen atoms of the carbonyl and nitroso groups. The solid chelates prepared behave as non-electrolytes in DMF solution. The coordination numbers of the obtained chelates using 3-methyl-4-nitroso-5-pyrazolone are four on applying the mole ratio 1:1 and six on using 1:2 mole ratio. In case of using the ligand 3-phenyl-4-nitroso-5-pyrazolone the coordination number is six in both cases.

Coordination polymers of copper( II) imides with polymeric heterocyclic Schiff bases of thiazole derivatives

Two polymeric ligands, L 1 and L 2 were synthesized by polymerizing new heterocyclic Schiff bases 2-hydroxy-1-benzylidene-2-amino-4-phenylthiazole and 2-hydroxy-1-benzylidene-2-amino-4-phenyl-5-phenylazothiazole, with 1,6-dichlorohexane. L 1 , L 2 gave solid chelates with copper(II) phthalimide or succinimide. The metal ion is coordinated through nitrogen of imide ion, nitrogen of azomethine group and oxygen of deprotonated phenolic group of polyligands. The studies indicate square-planar ligand field around copper ion. The presence of coordinated water is proved in the polychelates.

SYNTHESIS AND CHARACTERIZATION OF SOME 3-PHENYL-4-ARYLAZO-5-PYRAZOLONES WITH La(III), Ce(III), Th(IV), AND UO2(VI) COMPLEXES

La(III), Ce(III), Th(IV) and UO2(VI) chelates with 3-phenyl-4-arylazo-5-pyrazolones have been synthesized and were characterized by several analytical tools such as elemental analyses, IR, NMR, TG and molar conductance techniques. The data obtained show that all of the prepared complexes contain water and/or alcohol molecules in their coordination sphere and the ligands form 1:1 and 1:2 complexes which are in good agreement with the proposed formulae. The NMR data of the prepared ligands show the existence of the ketonic structure rather than the enolic form. The TG data revealed no crystal water outside the coordination sphere. The azopyrazolone ligands act as neutral bidentate ligands bonded to the metal ions through the oxygen atom of the carbonyl group and the α nitrogen of the arylazo group. All solid chelates prepared behave as non-electrolytes in DMF solution. The coordination numbers of the prepared chelates are ranging from 6 to 12 for 1:1 and from 7 to 12 for 1:2 chelates.

Synthese und Charakterisierung einiger neuer Lanthanid(III)-Chelate mit 1,4-bis-(2?-Hydroxyphenylazomethin)-phenylen

The chelates formed between 1,4-bis(2′-hydroxyphenylazomethine) phenylene with La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, and Lu ions have been investigated in solution using conductometric, potentiometric, and spectrophotometric methods. The studies revealed the formation ofM2L andML complexes. The solid chelates have been characterized by elemental and thermal analysis, molar conductance, IR,1H NMR (for La and Lu chelates), and electronic spectra. The bonding takes place through the coordination of nitrogen in the -CH=N- group and the oxygen of the hydroxyl group by proton displacement.

Determination of some lanthanide ions by conductometric and spectrophotometric measurements of their hydrazo-5-pyrazolone complexes

A series of complexes of 1-phenyl-3-methyl-4( x-phenylhydrazo)-5-pyrazolone [where x = 2-OCH 3 (i), 2-COOH (ii), 2-OH-5-Cl (iii), 2-OH-5-CH 3 (iv), and 2-SO 3 Na-4-CH 3 (v)] with trivalent lanthanide ions, Ln(III) were investigated and used for determination of these ions by conductometric and spectral measurements. The results indicate the probable formation of 1:1 and 1:2 chelates (metal:ligand). Solid chelates were isolated and their structures established by elemental analysis and infrared spectral data. The hydrazo stretching frequency of NHN = appeared in the range 1535 to 1520 cm −1, the carbonyl band from 1670 to 1650 cm −1, ν M − N from 575 to 565 cm −1, and ν M − O from 530 to 510 cm −1. Ln(III) coordinate with hydrazo-5-pyrazolone derivatives to form chelate rings with benzenoid type resonance through π-bonding from the metal to the ligand. The Yb 3+ complexes with 2-hydroxy-5-methyl (iv) derivative were also investigated in solutions by spectrophotometric studies and were very useful in the microdetermination of this element.

Studies on the chelation of cytosine, cytidine and cytidine phosphate with U(VI), Th(IV), Ce(III) and La(III)

The complexes formed between cytosine, cytidine and cytidine phosphate and U(VI), Th(IV), Ce(III) and La(III) have been investigated using spectrophotometric and conductometric methods. The apparent formation constants of these complexes have been calculated. The mode of bonding of the ligand in the solid chelates was studied by I.R. spectrophotometry which showed that chelate formation takes place through C(2)O and CN(3) groups in the case of cytosine and cytidine. The I.R. spectra of cytidine phosphate complexes indicated a tridentate ligand which coordinated via the former two groups and phosphate groups to the central metal ion.

Laser-raman and infrared spectroscopic characterization of some lanthanide-peri-dihydroxynaphthindenone chelates

The molecular formula of the solid chelates of lanthanideperi-dihydroxynaphthindenone was determined by chemical ionization mass spectrometry and elemental analysis. Laser-Raman and infrared spectra of these chelates were also recorded, discussed and band assignments made. Diagnostic stretching vibration bands at 410–470 and 265–280 cm−1 in the infrared and laser-Raman spectra, respectively, due to Ln-O bond were detected. The exact position of these bands was found to be dependent on the nature of the metal and was satisfactorily used for selective characterization of the lanthanide metal ions.