The synthesis and structure of a novel 1D copper(II) weak coordination polymer with 2,6-pyridinedicarboxylic acid

A novel copper complex, [Cu(dipic)(H₂O)₂] _n (H₂dipic?=?2,6-pyridinedicarboxylic acid), was synthesized and its crystal structure determined by X-ray diffraction. The complex has a polymeric structure of infinite one-dimensional (1D) zigzag chains, consisting of six-coordinate Cu(II) units. Each copper(II) ion is in a distorted octahedral environment with a CuNO₅ core: two oxygen atoms and one nitrogen atom from one dipic anion, one oxygen atom from an adjacent dipic ligand and two oxygen atoms from coordinated water. Each dipic anion connects two copper ions via a μ₂-oxygen atom. The zigzag 1D-chains are linked by extensive hydrogen bonds to form 2D infinite sheets.     

Study of the Ternary Complex Formation Between Vanadium(III), Dipicolinic Acid and Small Blood Serum Bioligands

Ternary complex formation reactions were studied between vanadium(III), dipicolinic acid and small molecular weight blood serum components: lactic, oxalic, citric and ortophosphoric acids. The electromotive force measurement permitted us to determine the chemical speciation of the complexes formed. In the vanadium(III)–dipicolinic acid–lactic acid system the complexes detected were: V(dipic)(lac), V(dipic)(lac)(OH)⁻ and V(dipic)(lac)(OH)₂^2-(\mathrm{OH})_{2}^{2-}. In the vanadium(III)–dipicolinic acid–oxalic acid system the observed complexes were: V(dipic)(ox)⁻, V(dipic)(ox)(Hox)²⁻ and V(dipic)(ox)₂^3-(\mathrm{ox})_{2}^{3-}. In the vanadium(III)–dipicolinic acid–citric acid system the complexes V(dipic)(Hcit)⁻, V(dipic)(cit)²⁻, V(dipic)(cit)(OH)³⁻, V(dipic)(cit)(OH)₂^4-(\mathrm{OH})_{2}^{4-} and V(dipic)(cit)(OH)₃^5-(\mathrm{OH})_{3}^{5-} were detected. Finally in the vanadium(III)–dipicolinic acid–phosphoric acid system the complexes V(dipic)(H₂PO₄) and V(dipic)(HPO₄)⁻ were observed. The UV-vis spectra allowed us to perform a qualitative characterization of the complexes formed in aqueous solution.     

Synthesis,characterization, crystal structure and biological activities of supramolecular compounds of Mn(II) and Zn(II) with dipicolinic acid and 8-hydroxyquinoline

Two compounds, (8-H₂Q)₂[Mn(dipic)₂] · 6H₂O (1) and (8-H₂Q)₂[Zn(dipic)₂] · 6H₂O (2) (8-HQ = 8-hydroxyquinoline (oxine), H₂dipic = dipicolinic acid), have been prepared and characterized by elemental, spectroscopic (IR and UV–Vis), and thermal analyses, magnetic measurements and single crystal X-ray diffraction techniques. Compounds 1 and 2 consist of two 8-hydroxyquinolinium cations, one bis(dipicolinato)M(II) anion (M = Mn(II) and Zn(II)) and six uncoordinated water molecules. Both 1 and 2 crystallize in the monoclinic space group C2/c. In the complex anion, each dipic ligand is tridentate through N of pyridine and oxygens of the carboxylate groups. Crystal packing of 1 and 2 is a composite of intermolecular hydrogen bonding interactions. The in vitro antibacterial and antifungal activities of 1 and 2 were evaluated by the agar well diffusion method by MIC (Minimal Inhibition Concentration), looking for compounds which display high-inhibitory effect against gram positive bacteria and fungi. No growth inhibition was observed against tested gram negative bacteria.     

Ternary Complex Formation between Vanadium(III), Dipicolinic Acid and Picolinic Acid in Aqueous Solution

Ternary complex species formed by the V³⁺ cation with the picolinic acid (Hpic, HL) and dipicolinic acid (H₂dipic, H₂L) ligands in aqueous solutions have been studied potentiometrically (25 °C, I=3.0 mol⋅dm⁻³ KCl ionic medium) and by spectrophotometric measurements. Application of the least-squares computer program LETAGROP to the experimental emf (H) data, taking into account the hydrolytic V(III) species and the binary V³⁺–picolinic acid and V³⁺–dipicolinic acid complexes, shows that under the investigated conditions the following ternary complexes are formed: [V(dipic)(pic)], [V(dipic)(pic)(OH)]⁻ and [V(dipic)(pic)₂]⁻. The stability constants of the ternary complexes were determined by potentiometric measurements whereas the spectrophotometric measurements were done in order to obtain a qualitative characterization of the complexes formed in aqueous solution.     

Crystal structures,theoretical calculations,spectroscopic and electrochemical properties of Cr(III) complexes with dipicolinic acid and 1,10-phenantroline

The crystal structures of compounds Na[Cr(dipic)₂] · 2H₂O (1) and [Cr(dipic)(phen)Cl] · 1/2H₂O (2), dipic = dipicolinate, phen = 1,10-phenantroline, were determined. In both complexes, Cr(III) is in a distorted octahedral environment. In complex (1), the metal is coordinated to two nearly perpendicular dipic anions acting as tridentate ligands through one oxygen of each carboxylate group and the pyridinic nitrogen atom. In complex (2), Cr(III) ion is similarly coordinated to a dipic anion, defining a ligand equatorial plane. The phen molecule bridges the remaining equatorial coordination site and one of the axial positions through its N-atoms. The other axial position is occupied by a chloride ion.     

Novel Complexes of Gallium(III), Indium(III), and Thallium(III) with Pyridine‐Containing Proton Transfer Ion Pairs Obtained from Dipicolinic Acid – Synthesis,Characterization and X‐ray Crystal Structure

Three new complexes of group thirteen metals, gallium(III), indium(III), and thallium(III) with proton transfer compounds, obtained from 2,6‐pyridinedicarboxylic acid (dipicolinic acid), were synthesized and characterized using elemental analysis, IR, ¹H and ¹³C NMR spectroscopy and single crystal X‐ray diffraction. The gallium(III) and indium(III) complexes were prepared using (pydaH₂)(pydc) (pyda = 2,6‐pyridinediamine, pydcH₂ = dipicolinic acid) and thallium(III) complex was obtained from (creatH)(pydcH) (creat = creatinine). The chemical formulae and space groups of the complexes are (pydaH)[Ga(pydc)₂] · 3.25H₂O · CH₃OH, ( 1 ), [In(pydc)(pydcH)(H₂O)₂] · 5H₂O, Pna2₁ ( 2 ) and [Tl₂(pydcH)₃(pydc)(H₂O)₂], ( 3 ). Non‐covalent interactions such as ion‐pairing, hydrogen bonding and π‐π stacking are discussed. The complexation reactions of pyda, pydc, and pyda + pydc with In³⁺ and Ga³⁺ ions in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described.     

PREPARATION AND PROPERTIES OF PYRIDINE DICARBOXYLIC ACID COMPLEXES OF THE LANTHANIDES

Abstract

The preparation and spectroscopic properties of eleven hydrated lanthanide (III) dipicolinate and quinolinate complexes are reported for the first time. The complexes are of three general types: M(dipi)(dipiH)(H₂O)₄, M(dipiH)₃(H₂O) and M(quin)(quinH)(H₂O)₃ [where M =lanthanide (III); dipiH₂ =pyridine-2,6-dicarboxylic acid (dipicolinic acid); quinH₂ =pyridine-2, 3-dicarboxylic acid (quinolinic acid)], and evidence is presented which indicates that they may be six-coordinate.     

Speciation of the Ternary Complexes of Vanadium(III)–Dipicolinic Acid and the Amino Acids Cysteine,Histidine, Aspartic and Glutamic Acids in 3.0 mol⋅dm<Superscript>−3</Superscript> KCl at 25 °C

In this work we present results for the speciation of the ternary complexes formed in the aqueous vanadium(III)–dipicolinic acid and the amino acids cysteine (H₂cys), histidine (Hhis), aspartic acid (H₂asp) and glutamic acid (H₂glu) systems (25 °C; 3.0 mol⋅dm⁻³ KCl as ionic medium), determined by means of potentiometric measurements. The potentiometric data were analyzed with the least-squares program LETAGROP, taking into account the hydrolysis of vanadium(III), the acid-base reactions of the ligands, and the binary complexes formed. Under the experimental conditions (vanadium(III) concentration = 2–3 mmol⋅dm⁻³ and vanadium(III): dipicolinic acid: amino acid molar ratio 1:1:1, 1:1:2 and 1:2:1), the following species [V(dipic)(H₂asp)]⁺, [V(dipic)(Hasp)], [V(dipic)(asp)]⁻, [V(dipic)(asp)(OH)]²⁻, and [V(dipic)(asp)(OH)₂]³⁻ were found in the vanadium(III)–dipicolinic acid–aspartic acid system. In the vanadium(III)–dipicolinic acid–glutamic acid system [V(Hdipic)(H₂glu)]²⁺, [V(dipic)(H₂glu)]⁺, [V(dipic)(Hglu)], [V(dipic)(Hglu)(OH)]⁻, and [V(dipic)(Hglu)(OH)₂]²⁻ were observed. In the vanadium(III)–dipicolinic acid–cysteine system the complexes [V(dipic)(H₂cys)]⁺, [V(dipic)(Hcys)], [V(dipic)(cys)]⁻, and [V(dipic)(cys)(OH)]²⁻ were present. And finally, in the vanadium(III)–dipicolinic acid–histidine system the complexes [V(Hdipic)(Hhis)]²⁺, [V(dipic) (Hhis)]⁺[\mathrm{V}(\mathrm{dipic}) (\mathrm{Hhis})]^{+}, [V(dipic)(his)], [V(dipic)(his)(OH)]⁻, and [V(dipic)(his)(OH)₂]²⁻ were observed. The stability constants of these complexes were determined. The species distribution diagrams as a function of pH are briefly discussed.     

Mono- and Bi-Nuclear Metal Complexes of Schiff-Base Hydrazone (ONN) Derived from o-Hydroxyacetophenone and 2-Amino-4-Hydrazino-6-Methyl Pyrimidine

A tridentate ONN donor Schiff-base hydrazone ligand, H₂L, was synthesized by the condensation of 2-amino-4-hydrazino-6-methyl pyrimidine with o-hydroxyacetophenone. The structure of the ligand was elucidated by IR and ¹H NMR spectra which indicated the presence of three different coordinating groups, the oxygen atom of the phenolic OH group, the nitrogen atom of the azomethine, C=N, group and one of the nitrogen atoms of the heterocyclic ring. The ligand behaves either as a tridentate (N₂O sites) neutral, mono- or di-basic ligand or as a bidentate (NO sites) monobasic ligand depending on the pH of the reaction medium and the metal ion. The mass spectrum of the ligand showed the presence of the molecular ion peak. Different types of metal complexes, mononuclear such as [(HL)M(OAc)]·xH₂O (M = Cu or Zn), [(HL)M(OAc)H₂O]·xH₂O (M = Ni or UO₂), [(HL)Co(OH₂)Cl]·2H₂O, [(H₂L)FeCl₃]·3½H₂O, [(L)FeCl(H₂O)₂]· 2¼H₂O, [(HL)L'FeCl(H₂O)]·H₂O (L' = 8-hydroxyquinoline, 8-HQ), [(HL)L'FeCl]Cl·xH₂O (L' = 1,10-phenanthroline, phen, or 2,2'-bipyridyl, bpy) and [(HL)L'Cu]·ClO₄ (L' = phen). Also, binuclear complexes with oxalic acid of the type [(HL)ClFe(ox)FeCl(HL)], [(HL)Cu(ox)Cu(HL)] were obtained. The IR spectra of the binuclear complexes indicated that the oxalate anion acts as a bridging tetradentate ligand. Elemental analyses, IR, electronic and ESR spectra as well as conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. Square-planar geometry is suggested for the Cu(II) complex, octahedral geometry for the Fe(III), Ni(II) complexes, tetrahedral geometry for the Co(II) and Zn(II) complexes and pentagonal-bipyramidal geometry for the UO₂(VI) complex.     

Synthesis,structures and properties of cobalt(III) and iron(III) complexes with a new triazamacrocycle, 1,4-diacetate-1,4,7-triazacyclodecane

A new bidisplaced acetate functionalized pendant arm derivative, 1,4-diacetate-1,4,7-triazacyclodecane (L) and its corresponding Co(III), Fe(III) complexes [CoLCl] (1) and [FeLCl]₂ · 3H₂O (2) were synthesized and characterized by elemental analysis, IR spectra,UV–Vis spectra, HNMR, MS, XPRD, TGA and single-crystal X-ray diffraction analysis. The crystal structure shows the metal ions in the complexes have similar coordination six-coordinate, by three nitrogens and two oxygens of the chelate ligand, and a chloride. Through calculation of the twist angle, we discover 1 forms a distorted octahedral geometry while 2 forms a distorted-prismatic geometry. In 2, there are abundant hydrogen bonds between the oxygen atoms of water and the nitrogens and oxygens of the ligand, resulting in a two-dimensional supramolecular network with a regular triatomic water cluster. The thermal gravimetric analyses of the two complexes are also given.     

Synthesis,spectral, antimicrobial,and thermal properties of Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) gliclazide complexes

The complexation between the lanthanide metal ions Ce(III), Gd(III), Nd(III), Tb(III), and Er(III) and gliclazide produced 1 : 1 molar ratio metal: gliclazide (Glz) complexes coordinated in a monodentate fashion via the OH group and having the general formulas [M(Glz)Cl₃(H₂O)]·xH₂O (M = Ce, Gd, Nd and x = 1, 3, 4, respectively) and [M(Glz)(H₂O)₄]Cl₃·yH₂O (M = Tb, Er and y = 1, 2, respectively). The structure of the synthesized lanthanide gliclazide complexes was assigned by IR, ¹HNMR, and UV-Vis spectroscopy. Thermal analysis and kinetic and thermodynamic parameters gave evidence for the thermal stability of the Glz complexes. The latter showed a significant antimicrobial effect against some bacteria and fungi.     

Ternary complexes of neodymium(III) and samarium(III) picrate triethylene glycol: structural, spectroscopic, and photoluminescent properties

The ternary complexation of neodymium(III) and samarium(III) with triethylene glycol (EO3) and picrate anion (Pic) were characterized by elemental analyses, FTIR (Fourier-transform infrared) spectroscopy, single crystal X-ray diffraction, and photoluminescence (PL). Both the [Nd(Pic)(H₂O)₂(NO₃)(EO3)](Pic) and [Sm(Pic)(H₂O)₂(NO₃)(EO3)](Pic)·H₂O complexes were isostructural with a ten-coordination number. In both complexes, the picrate and nitrate anions were coordinated to Ln(III) in a bidentate manner, and with the the EO3 ligand in a tetradentate manner, the addition of two water molecules maintained a ten-coordination number. The lighter lanthanide-picrate complexes formed a ten-coordination number due to the lanthanide contraction effect, acyclic polyether chain length, and number of donor oxygen atoms. The acyclic EO3 ligand affected photoluminescent intensity and its conformation on the structure of the [Ln(Pic)(NO₃)(H₂O)₂(EO3)]⁺ moiety. Photoluminescent measurement showed complex Nd(III) emissions at 403, 486, and 682?nm, with the strongest emission peak at 403?nm. Formation of these peaks occurred due to the intraligand π–π transitions of the Pic anion. The Sm(III) complex exhibited the emission characteristic of the Sm(III) ion in the red spectral region at 616.7?nm (⁴G_5/2 → ⁶H_9/2 transition), even though the ligand emissions were also observed in the PL spectrum. The emission intensity of the 4f–4f transitions in the Sm complex was significantly higher than that found in its salt. We noted that the [Sm(Pic)(H₂O)₂(NO₃)(EO3)](Pic)·H₂O complex was an excellent red-light-emitter and would be considered as a candidate material for organic light emitting diodes.     

One-dimensional coordination polymers of praseodymium(III)–vanadium(V) complexes with pyridine-2,6-dicarboxylic acid

This paper represents the hydrothermal synthesis of new isomorphous lanthanide–vanadium complexes with one-dimensional coordination polymers: [Pr₂(VO₂)₂(dipic)₄(H₂O)₉] · nH₂O with dipic = pyridine-2,6-dicarboxylic acid and n = 7.75. The structure determination shows a unique one-dimensional structure in which three types of chains run along the c-axis: the chain of positively charged praseodymium complexes bridged by a dipic ligand ([Pr(dipic)(H₂O)₅]⁺), the chain of negatively charged, stacked vanadium complexes ([VO₂(dipic)]⁻), and the chain of neutral praseodymium complexes with a bridged dipic ligand and a coordinating dipic ligand ([Pr(dipic)[VO₂(dipic)](H₂O)₄]). Such one-dimensional chains provide open channels which can accommodate water molecules. Not only accommodated water molecules but also ones coordinated to praseodymium ions were easily removed and absorbed upon heating at 200 °C and exposure of humidity at room temperature, respectively.     

A unique example of a co-crystal of [Ag(atr)2][Cr(dipic)2] (dipic = dipicolinate; atr = 3-amino-1H-1,2,4-triazole) and dinuclear [Cr(H2O)(dipic)(μ-OH)]2, with different coordination environment of Cr(III) ions

Treatment of a neutral aqueous solution of dipicolinic acid (dipicH₂), 3-amino-1H-1,2,4-triazole (atr) and CrCl₃·6H₂O in the presence of AgNO₃ (in molar ratio 1:1:1:3) under hydrothermal condition led to the formation of a co-crystal of {[Ag(atr)₂][Cr(dipic)₂]}₂·[Cr(H₂O)(dipic)(μ-OH)]₂·4H₂O (1). Compound 1 was characterized by elemental analyses, IR and UV-Vis spectroscopy as well as X-ray diffraction studies. The structure consists of two [Ag(atr)₂]⁺ cations, two [Cr(dipic)₂]⁻ anions, one co-crystallized neutral dinuclear chromium(III) complex, [Cr(H₂O)(dipic)(μ-OH)]₂, and four co-crystallized water molecules. Silver(I) ion in [Ag(atr)₂]⁺ is coordinated by two monodentate 3-amino-1H-1,2,4-triazole ligands, bound via endocyclic nitrogen atoms, in a linear fashion. Chromium(III) ion is octahedrally coordinated by two O,N,O-tridentate dipicolinate ligands in anionic complex. Each chromium(III) ion in neutral dinuclear complex, [Cr(H₂O)(dipic)(μ-OH)]₂, is octahedrally coordinated by one O,N,O-tridentate dipicolinate ligand, one water molecule and two bridging μ-OH ions in cis position. Thermal methods (TGA/DTA) confirm the number of co-crystallized water molecules in 1.     

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)₂X₂]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)₂ X₂] X₂ (X = Cl, Br and 1/2SO₄). The deprotonated ligand forms the complexes of the formulae M(ligand-H)₃ and Pt(ligand-H)₃Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.     

Reactions of 2-(1-carboxyl-2-hydroxyphenyl)thiazolidine with chromium(III) salts leading to newer synthesis of chromium(III) complexes

Reactions of 2-(L-carboxyl-2-hydroxyphenyl)thiazolidine with different chromium(III) salts [CrCl₃?·?6H₂O, K₃[Cr(SCN)₆], NH₄[Cr(NH₃)₂(SCN)₄]?·?H₂O, [Cr(urea)₆]Cl₃?·?3H₂O and [Cr(CH₃COO)₂H₂O]₂] under varied reaction conditions afforded many new mixed-ligand chromium(III) complexes. The ligand is a tridentate dibasic NSO donor except for complexes 1 and 4 where two moles of the ligand are present for each molecule of complex, one functioning as a dibasic tridentate (NSO) and the other as a monobasic bidentate (NS) (phenolic OH and carboxylic COOH groups remaining uncoordinated). The complexes have been characterized by elemental analyses, magnetic susceptibilities, molar conductances, molecular weights and spectroscopic (IR, Uv-vis) data. The ligand field parameters and NSH Hamiltonian parameters suggest tetragonal geometries of the complexes.     

Americium(III) coordination chemistry: An unexplored diversity of structure and bonding

The comparison of the physicochemical behavior of the actinides with that of the lanthanides can be justified by the analogy of their electronic structure, as each of the series is made up of elements corresponding to the filling of a given (n)f atomic shell. However relatively few points of comparison are available, given the lack of available structure for trans-plutonium(III) elements and the additional difficulty of stabilizing coordination complexes of uranium(III) to plutonium(III). This contribution is a focal point of trans-plutonium(III) chemistry and, more specifically, of some americium compounds that have been recently synthesized, all related with hard acid oxygen donor ligands that may be involved in the reprocessing chain of nuclear fuel. After a brief review of the solid hydrates and aquo species for the lanthanide and actinide families, we discuss two types of ligands that have in common three carboxylic goups, namely the aminotriacetic acid and the citric acid anions. The additional roles of the nitrogen atom for the first one and of the hydroxy function for the second one are discussed. Accordingly, five new complexes with either americium or lanthanides elements are described: [Co(NH₃)₆][M(NTA)₂(H₂O)]·8H₂O with M = Nd, Yb and Am, and [Co(NH₃)₆]₂K[M₃(Cit)₄(H₂O)₃]·18H₂O with Nd and Am cations. In all cases the americium complexes are isostructural with their lanthanide equivalents.     

Synthesis, Characterization and thermal behaviour of hemimellitic acid complexes with lanthanides(III)

The complexes of lanthanides(III) with hemimellitic acid (1,2,3-benzenetricarboxylic acid, H₃btc) of the formula Ln(btc)·nH₂O, where Ln=lanthanide(III) ion and n=2?6 were prepared and characterized by elemental analysis, infrared spectra, X-ray diffraction patterns and thermal analysis. The IR spectra of the complexes indicate coordination of lanthanides(III) through all carboxylate groups. The complexes of La(III), Ce(III), Pr(III) and Er(III) are amorphous. On heating in air atmosphere all complexes lose water molecules and next anhydrous compounds decompose to corresponding metal oxides.     

Thermogravimetric and spectroscopic studies on La(III) and Ce(III) complexes with some thio-schiff bases

Solid complexes of five derivatives of thio-Schiff bases with La(III) and Ce(III) ions were prepared and characterized by elemental and thermogravimetric analyses. The suggested general formula of the solid complexes is [ML₂(H₂O)X]·2H₂O, whereM=trivalent lanthanide ion,L=Schiff base andX=Cl^? or ClO ₄ ^? . Information about the water of hydration, the coordinated water molecules, the coordination chemistry and the thermal stability of these complexes was obtained and is discussed. Additionally, a general scheme of thermal decomposition of the lanthanide-Schiff base complexes is proposed.     

Aluminum(III), gallium(III), and indium(III) 4-hydroxyacridinato complexes

4-Hydroxyacridine (HAcr) is an O,N-chelating ligand whose coordination chemistry toward group 13 M(III) ions has received little attention. The molecular structure of HAcr consists of a 2,3-disubstituted-8-hydroxyquinoline; thus, in order to compare 8-hydroxyquinoline (HQ), 2-methyl-8-hydroxyquinoline (HMeQ′), and 2,3-disubstituted-8-hydroxyquinoline (HAcr) for steric and/or electronic influence, HAcr chelating ability toward the Al(III), Ga(III), and In(III) triad has been investigated. Irrespective of the nature of M(III), only complexes containing two equivalents of deprotonated HAcr are obtained. This article describes the synthesis and characterization of different series of bis-chelated pentacoordinated (Acr)₂MY (M = Al, Ga, In; Y = Cl, Br, I, NCS, N₃) or (Acr)₂MZ (M = Ga or In; HZ = C₆H₅OH, C₆H₁₃OC₆H₄OH, C₆H₅COOH, or C₆H₁₃OC₆H₄COOH) six-coordinate neutral (Acr)₂In(acac) (H(acac) =acetylacetone), or ionic [(Acr)₂In(N,N)][CF₃SO₃] (N,N = 2,2′-bipyridine or 1,10-phenanthroline) complexes. These results significantly contribute to elucidating the complexation capability of HAcr.