Synthesis, Crystal Structure and Optical Properties of Europium Trifluoroacetate Complexes with 1,10-Phenanthroline and 2,2-Bipyridine

Two europium trifluoroacetate complexes, Eu(CF₃COO)₃·phen ( 1 ) and Eu(CF₃COO)₃·bpy ( 2 ) (where phen=1,10‐phenanthroline, bpy=2,2′‐bipyridine), were synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), photoluminescence (PL) spectroscopy and thermogravimetric analysis (TA). Single‐crystal X‐ray structure has been determined for the complex [Eu₂(CF₃COO)₆·(phen)₃·(H₂O)₂]·EtOH. The crystal structure of [Eu₂(CF₃COO)₆·(phen)₃·(H₂O)₂]·EtOH shows that two different coordination styles with europium ions coexist in the same crystal and have entirely different coordination geometries and numbers. This crystal can be considered as an 1:1 adduct of [Eu(CF₃COO)₃·(Phen)₂·H₂O]·EtOH (9‐coordination part) and Eu(CF₃COO)₃·phen·H₂O (8‐coordination part). The excitation spectra of the two complexes demonstrate that the energy collected by "antenna ligands" is transferred to Eu³⁺ ions efficiently. The room‐temperature PL spectra of the complexes are composed of the typical Eu³⁺ ions red emission, due to transitions between ⁵D₀→⁷F_J(J=0→4). The lifetimes of ⁵D₀ of Eu³⁺ in the complexes were examined using time‐resolved spectroscopic analysis, and the lifetime values of Eu(CF₃COO)₃·phen and Eu(CF₃COO)₃·bpy were fitting with bi‐exponential (2987 and 353 µs) and monoexponential (3191 µs) curves, respectively. In order to elucidate the energy transfer process of the europium complexes, the energy levels of the relevant electronic states had been estimated. The thermal analyses indicate that they are all quite stable to heat.     

Complexation of radionuclide <Superscript>152+154</Superscript>Eu(III) with alumina-bound fulvic acid studied by batch and time-resolved laser fluorescence spectroscopy

To contribute to the understanding of Eu(III) interaction preperties on hydrous alumina particles in the absence and presence of fulvic acid (FA), the complexation properties of Eu(III) with hydrous alumina, FA and FA-alumina hybrids are studied by batch and time-resolved laser fluorescence spectroscopy (TRLFS) techniques. The continuous increase in the fluorescence lifetime of Eu-alumina and Eu-FA with increasing pH indicates that the complexation is accompanied by decreasing number of hydration water in the first coordination sphere of Eu(III). Eu(III) is adsorbed onto alumina particles as outer-sphere surface complexes of ≡(Al?O)?Eu· (OH)· 7H₂O and ≡(Al?O)?Eu· 6H₂O at low pH values, and as inner-sphere surface complexes as ≡(Al?O)₂?Eu⁺· 4H₂O at high pH. In FA solution, Eu(III) forms complexes with FA as (COO)₂Eu⁺(H₂O) _x and the hydration water number in the first coordination sphere decreases with pH increasing. The formation of ≡COO?Eu?(O?Al≡)· 4H₂O is observed on FA-alumina hybrids, suggesting the formation of strong inner-sphere surface complexes in the presence of FA. The surface complexes are also characterized by their emission spectra [the ratio of emission intensities of ⁵ D ₀→⁷ F ₁ (λ=594 nm) and ⁵ D ₀→⁷ F ₂ (λ=619 nm) transitions] and their fluorescence lifetime. The findings is important to understand the contribution of FA in the complexation properties of Eu(III) on FA-alumina hybrids that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Eu(III), or its analogue trivalent lanthanide and actinide ions in natural environment.     

Three New Ln-Decavanadates Materials:Synthesis,Structure, and Photoluminescent Sensing for Detection of Zn2+ and Co2+

Three new compounds, [Ln(H₂O)₈]₂[V₁₀O₂₈] · 8H₂O [Ln = Ho ( 1 ), Tb ( 2 )] and [Eu(H₂O)₈]₂[V₁₀O₂₈] · 9H₂O ( 3 ), were successfully synthesized by evaporating the mixture of K₆V₁₀O₂₈ · 10H₂O and LnCl₃ · 6H₂O. Notably, three vanadates are composed of [Ln(H₂O)₈]³⁺ cation, decavanadates ([V₁₀O₂₈]^6–) anion. Meanwhile, free water molecules generate different type water clusters to connect [V₁₀O₂₈]^6– anions and coordination cations to form 3D supramolecular structure. The fluorescence measurements reveal that characteristic photoluminescence of Tb^III and Eu^III is quenched in presence of [V₁₀O₂₈]^6–, then the impacts of variational decavanadates ions concentration on the fluorescence intensities of LnCl₃ (Ln = Tb, Eu) systems and different acetate solution [M(CH₃COO)₂; M = Ni, Cr, Cu, Co, Zn] on fluorescence intensities of Ln-decavanadates (Ln = Eu, Tb) systems are investigated.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Hendecanuclear [Cu_6Gd_5] magnetic cooler with high molecular symmetry of D_(3h)

A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_6Ln_5(μ_3OH)_9(C_4H_8O_2N)_6(C_5H_4ON)_6(H_2O)_9]·(ClO_4)_6·(H_2O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;Gd,5),was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid,2-hydroxypyridine,Cu(CH_3COO)_2·H_2O,and Ln(ClO_4)_3·6 H_2O.Notably,the [Cu_6Ln_5] clusters with high molecular symmetry ofD_(3 h) are rare examples of2-aminoisobutyric acid-based 3 d-4 f clusters.The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K,whereas the Gd-Cu exchange is an order of magnitude larger.Magnetization data collected for comp lex 5 yield a magnetic entropy change(-ΔSm) of 19.6 J kg ~1 K~11 at 3 K and 7 T,which may be attributed to the weak magnetic interactions between the component metal ions.     

Two 1-D europium coordination polymers: synthesis,crystal structure and fluorescence

Two new complexes {[Eu(2, 4-DFBA)₃ · (H₂O)₂] · H₂O} _n (1) and [Eu(2-BrBA)₃ · H₂O] _n (2) (2, 4-DFBA = 2, 4-difluorobenzoate, 2-BrBA = 2-bromobenzoate) have been synthesized and characterized by single crystal X-ray diffraction. 1 has a 1-D chain structure, in which Eu(III) ions are bridged by single COO^? groups and a 2-D supramolecular network is formed by hydrogen bond interactions. In 1, each Eu(III) is eight-coordinate with six oxygens from four 2,4-DFBA ligands and two waters. 2 has a 1-D chain structure, in which Eu(III) ions are bridged by bridging-chelating-bridging COO^? groups. In 2, each Eu(III) ion is nine-coordinate with eight oxygens from five 2-BrBA ligands and one water. The two complexes exhibit intense luminescence at room temperature. The ⁵D₀ → ⁷F _j (j = 0–4) transition emissions of Eu(III) have been observed.     

Syntheses, spectroscopic analysis, and structural determination of two novel nine-coordinate mononuclear Na4[EuIII(Dtpa)(H2O)]2 · 11.5H2O and binuclear (NH4)4[EuIII(Dtpa)]2 · 10H2O complexes

Two novel rare-earth metal complexes, namely, mononuclear Na₄[Eu^III(Dtpa)(H₂O)]₂ · 11.5H₂O (I) and binuciear (NH₄)₄[Eu^III(Dtpa)]₂ · 10H₂O (II) (H₅Dtpa = diethylenetriamine-N,N,N??,N??,N??-pentaacetic acid), have successfully been synthesized and characterized by infrared spectrum, UV-Vis spectrum, fluorescence spectrum, thermal analysis, and single-crystal X-ray diffraction techniques. Since these two Eu(III) complexes have different counterions, causing different coordination environment, fluorescence spectrum analysis displays different fluorescence properties. X-ray diffraction reveals that the coordination polyhedra of both complexes adopt pseudo-D _3h tricapped trigonal prismatic conformation. However, I is a nine-coordinate mononuclear complex and crystallizes in the monoclinic crystal space group P2₁/n and II is a nine-coordinate binuciear complex and crystallizes in the triclinic crystal space group $P\bar 1$ . In addition, II has two independent binuciear structural units, [Eu(1)₂(Dtpa)₂] and [Eu(2)₂(Dtpa)₂]. Along the yz plane both [Eu(1)₂(Dtpa)₂] and [Eu(2)₂(Dtpa)₂] form a 1D chain structure, respectively. Further, along the y axis linking of each other forms a 2D planar structure.     

Synthesis, characterization and electro-spectroelectrochemical studies of four macrocyclic Schiff-base Co(II) complexes having N2O2 set of donor atoms

Four macrocyclic Schiff-base cobalt complexes, [CoL¹][NO₃]₂ · 3H₂O, [CoL²][NO₃]₂ · 4H₂O, [CoL³][NO₃]₂ · 4H₂O and [CoL⁴][NO₃]₂ · 2H₂O, were synthesized by reaction of salicylaldehyde derivatives with 1,4-bis(3-aminopropoxy)butane or (±)-trans-1,2-diaminocyclohexane and Co(NO₃)₂ · 6H₂O by template effect in methanol. The metals to ligand ratio of the complexes were found to be 1:1. The Co(II) complexes are proposed to be tetrahedral geometry. The macrocyclic Co(II) complexes are 1:2 electrolytes as shown by their molar conductivities (Λ_M) in DMF (dimethyl formamide) at 10^?3 M. The structure of Co(II) complexes is proposed from elemental analysis, Ft-IR, UV–visible spectra, magnetic susceptibility, molar conductivity measurements and mass spectra. Electrochemical and thin-layer spectroelectrochemical studies of the complexes were comparatively studied in the same experimental conditions. The electrochemical results revealed that all complexes displayed irreversible one reduction processes and their cathodic peak potential values (E _pc) were observed in around of ?1.14 to 0.95 V. It was also seen that [CoL¹][NO₃]₂ · 3H₂O and [CoL²][NO₃]₂ · 4H₂O exhibited one cathodic wave without corresponding anodic wave but, [CoL³][NO₃]₂ · 4H₂O and [CoL⁴][NO₃]₂ · 2H₂O showed one cathodic wave with corresponding anodic wave, probably due to the presence of different ligand nature even if the complexes have the same N₂O₂ donor set. In view of spectroelectrochemical studies [CoL³][NO₃]₂ · 4H₂O showed distinctive spectral changes in which the intensity of the band (λ = at 316 nm, assigned to n → π* transitions) decreased and a new broad band in a low intensity about 391 nm appeared as a result of the reduction process based on the cobalt center in the complex.     

Synthesis,spectroscopic, and thermal analyses of trinuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with some sulfa derivatives

New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, ¹H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and ¹H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn₂L¹(AcO)₂(H₂O)₆] (1), [Co₂(L¹)₂(H₂O)₈] (2), [Ni₂L¹(AcO)₂(H₂O)₆] (3), [Mn₃L²(AcO)₃(H₂O)₉] (5), [Co₃L²(AcO)₃(H₂O)₉] · 4H₂O (6), [Ni₃L²(AcO)₃(H₂O)₉] · 7H₂O (7), [Mn₃L³(AcO)₃(H₂O)₆] (9), [Co₂(HL³)₂(H₂O)₈] · 4H₂O (10), [Ni₃L³(AcO)₃(H₂O)₉] (11), [Mn₃L⁴(AcO)₃(H₂O)₉] · H₂O (13), [Co₂(HL⁴)₂(H₂O)₈] · 5H₂O (14), and [Ni₃L⁴(AcO)₃(H₂O)₉] (15) while [Zn₂L¹(AcO)₂(H₂O)₂] (4), [Zn₃L²(AcO)₃(H₂O)₃] · 2H₂O (8), [Zn₃L³(AcO)₃(H₂O)₃] · 3H₂O (12), and [Zn₃L⁴(AcO)₃(H₂O)₃] · 2H₂O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]⁺ and fragments supporting the formulation.     

Structural variation from linear,layer to 3D framework: Syntheses,structures and luminescence

Self‐assembly of Zn (II) or Cd (II) nitrates, flexible bis (pyridyl)‐diamine, as well as arenesulfonic acids, leads to the formation of ten coordination polymers, namely, [Zn(L1)(H₂O)₃]·2(p‐TS)·2H₂O ( 1 ), [Zn(L1)(H₂O)₂]·2(p‐TS)·2H₂O ( 2 ), [Zn(L1)₂(p‐TS)₂] ( 3 ), [Zn(H₂L1)(H₂O)₄]·2(1,5‐NDS)·2H₂O ( 4 ), [Zn(H₂L2)(H₂O)₄]·2(1,5‐NDS)·4MeOH ( 5 ), [Cd(L1)(p‐TS)(NO₃)]·H₂O ( 6 ), [Cd(L1)(1,5 ‐NDS)_0.5(H₂O)]·0.5(1,5‐NDS)·H₂O ( 7 ), [Cd(L2)(H₂O)₂]·(p‐TS)·(NO₃)·3H₂O ( 8 ), [Cd(L2)(1,5‐NDS)] ( 9 ) and [Cd(L2)(1,5‐NDS)]·MeOH ( 10 ) (L1 = N,N′‐bis (pyridin‐4‐ylmethyl) ethane‐1,2‐diamine, L2 = N,N′‐bis (pyridin‐3‐ylmethy l)ethane‐1,2‐diamine, p‐HTS = p‐toluenesulfonic acid, 1,5‐H₂NDS = 1,5‐naphthalene disulfonic acid), which have been characterized by elemental analysis, IR, TG, PL, powder and single‐crystal X‐ray diffraction. Complexes 1 , 4 , 5 and 6 present linear or zigzag chain structures accomplished by the interconnection of adjacent M (II) cations through L1 ligands or protonated H₂L1²⁺/H₂L2²⁺ cations, while complexes 2 , 3 and 8 show similar (4,4) layer motifs constructed from the connection of M (II) cations through L1 and L2. The same coordination modes of L1 and L2 in complexes 7 and 9 join adjacent Cd (II) cations to form double chain structures, which are further connected by bis‐monodentate 1,5‐NDS^2? dianions into different (6,3) and (4,4) layer motifs. The L2 molecules in complex 10 join adjacent Cd (II) cations together with 1,5‐NDS^2? dianions to form 3D network with hxl topology. Therefore, the diverse coordination modes of the bis (pyridyl) ligand with chelating spacer and the feature of different arenesulfonate anions can effectively influence the architectures of these complexes. Luminescent investigation reveals that the emission maximum of these complexes varies from 374 to 448 nm in the solid state at room temperature, in which complexes 4 , 5 , 7 , 9 and 10 show average luminescence lifetimes from 7.20 to 14.82 ns. Moreover, photocatalytic properties of complexes 7–10 towards Methylene blue under Xe lamp irradiation are also discussed.     

Mixed and partial oxidation states. Photoelectron spectroscopic evidence

X-ray photoelectron spectra of the single valence platinum complexes K₂[Pt(CN)₄] · 3H₂O(1),K₂[Pt(CN)₄]Cl_0.3 · n H₂O(2) and K₂[Pt(CN)₄]Cl₂ · 3H₂O(3) and the mixed valence compound [Pt^II(C₂H₅NH₂)₄]Cl₄ · [Pt^IV (C₂H₅NH₂)₄Cl₂] · 4H₂O(4) have been measured. It is found that one can distinguish clearly between mixed and single valence compounds by electron spectroscopy. The Pt spectrum of (4) is a superposition of a Pt^II and Pt_IV spectrum. The chemical shift between (1) and (3) is normal, however (2) shows an anomalous low binding energy for the Pt 4f electrons. The importance of using reliable reference peaks for obtaining absolute binding energies is emphasized.     

Synthesis, spectroscopic, and thermal investigation of transition and non-transition complexes of metformin as potential insulin-mimetic agents

Complexes of [Mn(MF)₂(Cl)₂]·2H₂O (1), [Fe(MF)₂(Cl)₂]Cl·4H₂O (2), [Ni(MF·HCl)₂(Cl)₂]·6H₂O (3), [Cu(MF·HCl)₂(Cl)₂] (4), [Zn(MF·HCl)₂](NO₃)₂·6H₂O (5), [Cd₂(MF·HCl)(Cl)₄(H₂O)] (6), [Mg(MF·HCl)₂(Cl)₂]·6H₂O (7), [Sr₂(MF·HCl)(Cl)₄(H₂O)] (8), [Ba(MF·HCl)₂(Cl)₂]·2H₂O (9), [Pt(MF)₄] (10), [Au(MF)₃]Cl₃ (11), and [Pd(MF)₂]Cl₂ (12) were synthesized from Legitional behavior of metformin drug as a diabetic agent. The authenticity of the transition and non-transition metal complexes were characterized by elemental analyses, molar conductivity, (infrared, UV–Vis) spectra, effective magnetic moment in Bohr magnetons, electron spin resonance, thermal analysis, X-ray powder diffraction as well as scanning electron microscopy. Infrared spectral studies as well as elemental analyses revealed the existence of metformin in the base or hydrochloride salt forms in the chelation state acts as a bidentate ligand while the platinum(IV) complex is coordinated through the deprotonation of –NH group. The magnetic and electronic spectra of Mn(II), Fe(III), Ni(II), and Cu(II) complexes suggest an octahedral geometry. Antimicrobial screening of metformin and its complexes were determined against the (G⁺ and G^?) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans).     

Ten complexes constructed by two reduced Schiff base tetraazamacrocycle ligands: syntheses,structures, magnetic and luminescent properties

Ten new complexes, [Cu₂(L¹)(NO₃)₂]·2H₂O (1), [Cu₄(L¹)₂]·4ClO₄·H₂O (2), [Cu₂(L¹)(H₂O)₂]·(adipate) (3), [Cu₆(L¹)₂(m-bdc)₄]·2DMF·5H₂O (4), [Cu₂(L¹)(Hbtc)]·5H₂O (5), [Cu₂(L¹)(H₂O)₂]·(ntc)·3H₂O (6), [Co₂(L²)]·[Co(MeOH)₄(H₂O)₂] (7), [Co₃(L²)(EtOH)(H₂O)] (8), [Ni₆(L²)₂(H₂O)₄]·H₂O (9) and [Zn₄(L²)(OAc)₂]·0.5H₂O (10), have been synthesized. 1 displays a [Cu₂(L¹)(NO₃)₂] monomolecular structure. 2 shows a supramolecular chain including [Cu₂L¹]²⁺. In 3, two Cu(II) ions are connected by L¹ to form a [Cu₂(L¹)(H₂O)₂]²⁺ cation. In 4, the m-bdc anions bridge Cu(II) ions and L¹ anions to form a layer. Both 5 and 6 display 3-D supramolecular structures. 7 consists of both [Co₂L²]^2? and [Co(MeOH)₄(H₂O)₂]²⁺ units. 8 and 9 show infinite chain structures. In 10, Zn(II) dimers are linked by L² to generate a 3-D framework. The magnetic properties for 4 and 8 and the luminescent property for 10 have been studied.     

The Fe2+ chelate of hydrazinecarboxylic acid studied by the Mössbauer effect

The chelate compounds K[Fe(hyc)₃] and N₂H₅[Fe(hyc)₃]·H₂O (hyc = N₂H₃COO) were studied by the Mössbauer effect of ⁵⁷Fe at various temperatures. At room temperature the quadrupole splitting parameter is 2.77 mm/sec for K[Fe(hyc)₃] and 2.35 mm/sec for N₂H₅[Fe(hyc)₃]·H₂O, and the center shift is 1.08 mm/sec for both compounds. The temperature dependences of the quadrupole parameters yielded the crystal field splittings of the ⁵T_2g levels of the Fe²⁺ ions which indicate large trigonal distortion of the Fe(hyc)₃ anion. Using a molecular crystal-like treatment of the ferrous ion vibrations the temperature dependence of the recoilless fraction gave an effective Debye temperature Θ_D = 71°K for K[Fe(hyc)₃] and Θ_D = 90°K for N₂H₅[Fe(hyc)₃]·H₂O. No evidence for magnetic ordering was found down to 4.5°K in either compound.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.     

Structural features of the crystalline iodide complexes of some rare-earth elements with carbamide and acetamide

New acetamide and carbamide complexes LnI₃ · 4Ur · 4H₂O (Ln = La, Eu, Dy, Ho, Y; Ur is carbamide) and LnI₃ · 4AA · 4H₂O (Ln = Nd, Eu, Dy, Ho, Y; AA is acetamide) are synthesized. The complexes are characterized by the data of chemical analysis, IR spectroscopy, and X-ray diffraction analysis. The ligands (water, carbamide, and acetamide molecules) are coordinated by the rare-earth element atoms through the oxygen atom, and the coordination polyhedron is a distorted square antiprism. The iodide ions are not coordinated and are located in the external sphere. The structural characteristics of the complexes are compared in the series [Ln(L)₄(H₂O)₄]I₃ (Ln = La, Nd, Eu, Gd, Dy, Ho, Er; L = AA, Ur).     

Influence of the steric properties of pyridine ligands on the structure of complexes containing the {LnCd2(bzo)7} fragment

The reaction of Cd(NO₃)₂ · 4H₂O and Eu(NO₃)₃ · 6H₂O or Tb(NO₃)₃ · 6H₂O with potassium 3,5-di-tert-butylbenzoate (Kbzo) and N-donor ligands (1,10-phenanthroline (phen), 2,4-lutidine (2,4-lut), 3,4-lutidine (3,4-lut), phenanthridine (phtd), 2,3-cyclododecenopyridine (cdpy), acridine (acr)) afforded heterometallic LnCd₂ complexes: [EuCd₂(bzo)₇(EtOH)₂(phen)] (2), [LnCd₂(bzo)₇(2,4-lut)₄] (Ln = Eu (3), Tb (4)), [EuCd₂(bzo)₇(H₂O)₂(2,4-lut)₂] · MeCN (5), [EuCd₂(NO₃)(bzo)₆(EtOH)₂(2,4-lut)₂] (6), [EuCd₂(bzo)₇(H₂O)(EtOH)(3,4-lut)₂] · 5EtOH (7), 3[EuCd₂(bzo)₇(H₂O)₂(phtd)₂] · 4phtd (8), [EuCd₂(bzo)₇(EtOH)₃(cdpy)] (9), 2[EuCd₂-(bzo)₂(EtOH)₄] · acr (10). The structures of complexes 2, 3, and 5–10 were determined by single-crystal X-ray diffraction. The isostructurality of complexes 3 and 4 was confirmed by powder X-ray diffraction. The structure of the trinuclear {Ln₂Cd} metal core is stable and independent of the type of peripheral ligands coordinated to cadmium atoms. Photoluminescent properties of compounds 3 and 4 were studied.

     

One‐Dimensional Channels Encapsulated in Supramolecular Networks Constructed of Zinc(II), Manganese(II), or ­Nickel(II) Atoms with 3‐(Carboxymethyl)‐2, 7‐dimethyl‐3H‐benzo[d]imidazole‐5‐carboxylic Acid

Four complexes with supramolecular architectures, namely, MZCA · 3H₂O ( 1 ), [Zn(H₂O)₆]²⁺ · [MZCA]₂ · [H₂O]₆ ( 2 ), [Mn(MZCA)₂(H₂O)₄] · 2H₂O ( 3 ), and [Ni(MZCA)₂(H₂O)₄] · 2H₂O ( 4 ) [MZCA = 3‐(carboxymethyl)‐2, 7‐dimethyl‐3H‐benzo[d]imidazole‐5‐carboxylic acid], were synthesized and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. Complexes 1 and 2 display a remarkable 3D network with 1D hydrophilic channels. Complexes 3 and 4 are isostructural and exhibit a 3D structure encapsulating 1D 24‐membered ring microporous channels. The UV/Vis and fluorescent spectra were measured to characterize complexes 1 – 4 . The thermal stability of complexes 2 – 4 were also examined.     

Synthesis, Spectral and Thermal Analyses of Novel Bi- and Polyhomonuclear Complexes of Pyrimidine Bisazo-dianil Derivatives

Seven new bi‐ and polyhomonuclear transition metal complexes with three polyhydroxlated bisazodianil ligands were synthesized and characterized. The ligands were derived from condensation of 6‐(5‐formyl‐2‐hydroxyphenylazo)‐2,4‐dihydroxypyrimidine with aliphatic diamines (H₈L¹, H₈L² and H₆L³). The data of elemental and thermal analyses, molar conductance measurement, IR, electronic and ESR spectra as well as magnetic moment measurements support the formation of [L¹Co₇Cl₆(H₂O)₁₀]·22H₂O ( 1 ), [H₂L²Mn₆Cl₆(H₂O)₈]·3H₂O·2EtOH ( 3 ), [L²Co₈Cl₈(H₂O)₁₂]·24H₂O ( 4 ), [H₄L³Co₂Cl₂(H₂O)₂]·8H₂O·2EtOH ( 6 ) with a tetrahedral geometry and [H₂L¹Ni₅Cl₄(H₂O)₁₆]·19H₂O·EtOH ( 2 ), [L²Ni₈Cl₈(H₂O)₂₈]·8H₂O·EtOH ( 5 ) with an octahedral geometry while [H₆L³Cu₃(H₂O)₇]Cl₃·10H₂O ( 7 ) has a distorted tetrahedral arrangement. The mode of bonding between the metal ions and the ligand molecules is determined and the metal‐metal interaction was studied. The activation thermo‐kinetic parameters for the thermal decomposition steps of the complexes E*, ΔH*, ΔS*, and ΔG* were calculated.     

Copper(II) and Cadmium(II) Complexes Based on N,N‐Bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine Ligand: Syntheses,Structures, Magnetic,and Luminescent Properties

The reaction of the aryl‐oxide ligand H₂L [H₂L = N,N‐bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine] with CuSO₄ · 5H₂O, CuCl₂ · 2H₂O, CuBr₂, CdCl₂ · 2.5H₂O, and Cd(OAc)₂ · 2H₂O, respectively, under hydrothermal conditions gave the complexes [Cu(H₂L¹)₂] · SO₄ · 3CH₃OH ( 1 ), [Cu₂(H₂L²)₂Cl₄] ( 2 ), [Cu₂(H₂L²)₂Br₄] ( 3 ), [Cd₂(HL)₂Cl₂] ( 4 ), and [Cd₂(L)₂(CH₃COOH)₂] · H₂L ( 5 ), where H₂L¹ [H₂L¹ = 2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenol] and H₂L² [H₂L² = 2‐(2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenoxy)‐4, 6‐dimethylphenol] were derived from the solvothermal in situ metal/ligand reactions. These complexes were characterized by IR spectroscopy, elementary analysis, and X‐ray diffraction. A low‐temperature magnetic susceptibility measurement for the solid sample of 2 revealed antiferromagnetic interactions between two central copper(II) atoms. The emission property studies for complexes 4 and 5 indicated strong luminescence emission.