Bispidines for Dual Imaging

The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields functional bispidines enabling convenient functionalization for targeted imaging. The BODIPY‐substituted bispidine 3 combines a coordination site for metal ions, such as radioactive ⁶⁴Cu^II, with a fluorescent unit. Product 3 was thoroughly characterized by standard analytical methods, single crystal X‐ray diffraction, radiolabeling, and photophysical analysis. The luminescence of ligand 3 was found to be strongly dependent on metal ion coordination: Cu^II quenches the BODIPY fluorescence, whereas Ni^II and Zn^II ions do not affect it. It follows that, in imaging applications with the positron emitter ⁶⁴Cu^II, residues of its origin from enriched ⁶⁴Ni and the decay products ⁶⁴Ni^II and ⁶⁴Zn^II, efficiently restore the fluorescence of the ligand. This allows for monitoring of the emitted radiation as well as the fluorescence signal. The stability of the ⁶⁴Cu^II? 3 complex is investigated by transmetalation experiments with Zn^II and Ni^II, using fluorescence and radioactivity detection, and the results confirm the high stability of ⁶⁴Cu^II? 3 . In addition, metal complexes of ligand 3 with the lanthanide ions Tb^III, Eu^III, and Nd^III are shown to exhibit emission of the BODIPY ligand and the lanthanide ion, thus enabling dual emission detection.     

A new oxamato-bridged heterotrinuclear NiIICuIINiII complex: synthesis,structure and properties

A new oxamato-bridged Ni^IICu^IINi^II species, [Ni(iprtacn)]₂[Cu(pba)(H₂O)_0.5](BPh₄)₂ (1), (iprtacn?=?1,4,7-triisopropyl-1,4,7-triazacyclononane; pba?=?1,3-propylenebis(oxamato)) has been synthesized and structurally as well as magnetically characterized. Complex 1 has a discrete trinuclear Ni^IICu^IINi^II structure: Two nickel(II) ions are bridged by [Cu(pba)]^2? with the macrocyclic ligand iprtacn a terminal ligand of nickel(II). Fitting the magnetic data of 1 led to g _Cu?=?2.16, g _Ni?=?2.18, J?=??112.5?cm^?1, D?=?±7.78?cm^?1. The irregular spin state structure and interaction of complex 1with DNA are described here.     

Redox switchable ligands suitable for transition metal ions: Protonation,complexation and electrochemical properties of a ferrocene-modified tetraamine diketone and its saturated analogue

Abstract

The new ferrocene-containing water-soluble ligands 1 and 2 were synthesized and their protonation and complexation properties toward Ni^II and Cu^II studied as a function of pH, by means of potentiometric titration experiments. Electrochemical measurements were performed in aqueous solution on pure 1 and 2 and in the presence of Ni^II and Cu^II cations, in the pH range 2–12, allowing us to determine the redox potential values relative to the ferrocene oxidation in the free ligands and in their Ni^II and Cu^II complexes. 1 and 2 behave as redox switchable ligands, the former enhancing, the latter decreasing its binding ability upon oxidation of the appended ferrocene function. Besides, the Cu^II complex of ligand 1 and the Ni^II complex of ligand 2 behave as two-centre two-electron redox systems, the complexed metal cation being subject to further oxidation to M^III.     

Heterotrimetallic Coordination Polymers: {CuIILnIIIFeIII} Chains and {NiIILnIIIFeIII} Layers: Synthesis,Crystal Structures,and Magnetic Properties

The use of the [Fe^III(AA)(CN)₄]^? complex anion as metalloligand towards the preformed [Cu^II(valpn)Ln^III]³⁺ or [Ni^II(valpn)Ln^III]³⁺ heterometallic complex cations (AA=2,2′‐bipyridine (bipy) and 1,10‐phenathroline (phen); H₂valpn=1,3‐propanediyl‐bis(2‐iminomethylene‐6‐methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[Cu^II(valpn)Ln^III(H₂O)₃(μ‐NC)₂Fe^III(phen)(CN)₂ {(μ‐NC)Fe^III(phen)(CN)₃}]NO₃ ? 7 H₂O}_n (Ln=Gd ( 1 ), Tb ( 2 ), and Dy ( 3 )) and the trinuclear complex [Cu^II(valpn)La^III(OH₂)₃(O₂NO)(μ‐NC)Fe^III(phen)(CN)₃] ? NO₃ ? H₂O ? CH₃CN ( 4 ) were obtained with the [Cu^II(valpn)Ln^III]³⁺ assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[Ni^II(valpn)Ln^III(ONO₂)₂(H₂O)(μ‐NC)₃Fe^III(bipy)(CN)] ? 2 H₂O ? 2 CH₃CN}_n (Ln=Gd ( 5 ), Tb ( 6 ), and Dy ( 7 )) resulted with the related [Ni^II(valpn)Ln^III]³⁺ precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [Cu^II(valpn)La^III(OH₂)₃(O₂NO)(μ‐NC)Fe^III(phen)(CN)₃]⁺, nitrate counterions, and non‐coordinate water and acetonitrile molecules. The heteroleptic {Fe^III(bipy)(CN)₄} moiety in 5 – 7 acts as a tris‐monodentate ligand towards three {Ni^II(valpn)Ln^III} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the Cu^II?Ln^III ( 1 – 3 ) and Ni^II?Ln^III ( 5 – 7 ) units, as well as through the single cyanide bridge between the Fe^III and either Ni^II ( 5 – 7 ) or Cu^II ( 4 ) account for the overall ferromagnetic behavior observed in 1 – 7 . DFT‐type calculations were performed to substantiate the magnetic interactions in 1 , 4 , and 5 . Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out‐of‐phase ac signals below 4.0 K in the lack of a dc field, the values of the pre‐exponential factor (τ_o) and energy barrier (E_a) through the Arrhenius equation being 2.0×10^?12 s and 29.1 cm^?1, respectively. In the case of 7 , the ferromagnetic interactions through the double phenoxo (Ni^II–Dy^III) and single cyanide (Fe^III–Ni^II) pathways are masked by the depopulation of the Stark levels of the Dy^III ion, this feature most likely accounting for the continuous decrease of χ_M T upon cooling observed for this last compound.     

Chelatbildung mit 1,3-Diamino-2-methylenpropanen

Chelate Formation with 1,3-Diamino-2-methylene Propane1 1,3-Diamino-2-methylene propane and its N, N′ alkylated derivatives form crystalline chelates with Co^II (1:3), Ni^II (1:1, 1:2 and 1:3), Pd^II (1:1, 1:2), Rh^III (1:1) and Cu^II (1:2). Experiments for preparation of olefin complexes were unsuccessful. By potentiometric measurements the base strengths of the ligands as well as the stability constants of the Co^II, Ni^II, Pd^II, Cu^II, Zn^II, Cd^II chelates were evaluated and the kinetics of the formation of the 1:1 Pd^II complex is investigated. The magnetic behaviour of the Co^II?, Pd^II? and Cu^II? chelates is normal, whereas[Ni(dia)₂(H₂O)₂] (ClO₄)₂ shows anormal behaviour due to configurational isomerism between square planar and octahedral ligand geometry in solid state in type of a LIFSCHITZ -isomerism. The ESR-spectra of the Cu^II?compounds are discussed and the bonding parameters of the Cu? N?bonds were calculated.     

Synthesis and reactivity of metal-containing monomers

Acid and neutral Co^II, Cu^II, Ni^II, Zn^II, Fe^II, and Fe^III maleates, fumarates, and itaconates were obtained and characterized. The methods for their synthesis were optimized, and the valence state and coordination of metals were studied. Co^II and Fe^II hydrogen maleates, Co^II maleate, and Co^II fumarate were examined by X-ray diffraction analysis. The ligands based on unsaturated dicarboxylic acids can be mono-, bi-, and tetradentate, which results in the formation of acid salts, chain and three-dimensional coordination polymers, whose double bond is not involved in the coordination. The strong antiferromagnetic exchange (μ_elf=1.41 and 0.34 μ_B at 290 and 80 K, respectively) was detected in Cu^II itaconate. Based on the data of Mössbauer spectroscopy, the partial reduction of Fe^III to Fe^II during the synthesis of Fe^III maleate was shown to occur: δFe=0.43 and 1.27 mm s^?1, ΔE _Q=0.57 and 3.13 mm s^?1 and Γ=0.37 and 0.28 mm s^?1 atT=298 K for Fe^III and Fe^II, respectively.     

Synthesis,Crystal Structure,and Characterization of Two Oxamido‐bridged NiIICuIINiII Heteronuclear Complexes

Two new trinuclear complexes [Cu^II(Ni^IIX₁)₂(C₂H₅OH)₂]· (ClO₄)₂·2(CH₃OH) ( 1 ) and [Cu^II(Ni^IIX₂)₂(H₂O)]·(ClO₄)₂· 0.75(H₂O) ( 2 ) (X₁ = dianion of 5,6;13,14‐dibenzo‐7,12‐bis(ethoxycarboxyl)‐9‐methyl‐2,3‐dioxo‐1,4,8,11‐tetraazacyclotetradeca‐7,11‐diene. X₂ = dianion of 5,6;13,14‐dibenzo‐9,10‐cyclohexano‐7,12‐bis(ethoxycarboxyl)‐2,3‐dioxo‐1,4,8,11‐tetraazacyclotetradeca7,11‐diene.) have been synthesized and characterized by single crystal X‐ray analysis, elemental analysis, IR, UV and EPR spectroscopies. The complexes consist of Ni^IICu^IINi^II heteronuclear cationic entities. The central Cu^II atom of 1 lies in an octahedral coordination environment, while that of 2 resides in a square‐pyramidal coordination sphere. The adjacent trinuclear units of 1 are linked together through π‐π stacking interactions resulting in a 1D supramolecular chain, whereas the π‐π stacking interactions between the contiguous units of 2 lead to a 2D structure. The EPR spectra of the two complexes show a signal of an axially elongated octahedral Cu^II system in 1 and an axially elongated square‐pyramidal Cu^II system in 2 , respectively. The hyperfine splitting of the Cu^II atoms (I^Cu = 3/2) has also been observed in the EPR spectra.     

Ambidenticity of a tridentate oxygen-nitrogen donor towards bivalent and trivalent transition metal ions

Summary N-salicylidene anthranilamide (H₂SAA) and its Cr^III, Mn^II, Fe^III, Co^II, Ni^II and Cu^II complexes were prepared and characterized by physicochemical and spectroscopic data. H₂SAA enolizes to give a dibasic ONO donor set in the divalent metal complexes. It also binds to the trivalent metal ions in a nonenolized form using a monobasic ONN donor set. Co^II is oxidized to Co^III during complexation. Octahedral geometries are proposed for Cr^III, Mn^II, Fe^III and Co^III complexes, while square planar geometries are suggested for the Ni^II and Cu^II complexes. Phenoxide bridging in the Cr^III and Fe^III complexes and enoxide bridging in the Ni^II and Cu^II complexes is proposed.     

Complexes of 1-isonicotinoyl-4-benzoyl-3-thiosemicarbazide with manganese(II), iron(III), chromium(III), cobalt(II), nickel(II), copper(II) and zinc(II)

1-Isonicotinoyl-4-benzoyl-3-thiosemicarbazide (IBtsc) and its Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II and Zn^II complexes have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis., i.r., n.m.r. and FAB mass spectral data. The room temperature e.s.r. spectra of the Cr^III, Fe^III and Cu^II complexes yield values, characteristic of octahedral, tetrahedral and square-planar complexes, respectively. The Mössbauer spectra of [Fe(IBtsc-H)Cl₂] at room temperature and at 78 K suggest the presence of high-spin Fe^III. The Ni^II, Cr^III and Cu^II complexes show semiconducting behaviour in the solid state, but the Zn^II complex is an insulator at room temperature. IBtsc and its soluble complexes have been screened against several bacteria, fungi and tumour cell lines.     

Non-covalent strategy for activating separation and detection functionality by use of the multifunctional host molecule thiacalixarene

This review article proposes a non-covalent strategy for activating separation and detection functionality; this strategy acts not through extensive organic synthesis to a covalently constructed molecular receptor, but by combining a simple molecular platform with a chemical “field” or functional component. For such a platform, we employed thiacalixarenes—calixarenes in which the bridging methylene groups are replaced with sulfur—to demonstrate usefulness of the non-covalent strategy and the multifunctionality of thiacalixarene. Thiacalixarene exhibits inherent abilities to recognize metal ions by coordinating with the bridging sulfur and adjacent phenol oxygen, as well as to include organic guest molecules in the cavity. Moreover, the non-covalent coupling of thiacalixarene provides systems with functions higher than thiacalixarene by itself. The functions described in this paper are as follows: (1) a 200-fold pre-concentration of heavy metal ions such as Cu^II, Cd^II, and Pb^II; (2) a pre-column derivatization reagent for the highly selective and sensitive determination of Ni^II, Al^III, Fe^III, and Ti^IV at sub-ppb levels with reversed-phase HPLC; (3) the self-assembled formation of a luminescence receptor with Tb^III ions for the detection of 10^?10 M levels of 1-ethylquinolinium guest; and (4) a sensing system for 10^?9 M levels of Ag^I ions by the formation of the Ag^I-Tb^III-thiacalixarene ternary supramolecular complex. These examples support the non-covalent strategy as a highly promising way to obtain functions beyond that of a molecular platform. In addition, these diverse functions indicate the multifunctionality of thiacalixarene as well as its suitability to the non-covalent strategy, since the inherent functional groups—such as the bridging sulfur, phenol oxygen, p-substituent, aromatic ring, and hydrophobic cavity—synergistically perform the functions.     

Complexes of a tridentate ONS Schiff base. Synthesis and biological properties

Several new complexes of a tridentate ONS Schiff base derived from the condensation of S-benzyldithiocarbazate with salicylaldehyde have been characterised by elemental analyses, molar conductivity measurements and by i.r. and electronic spectra. The Schiff base (HONSH) behaves as a dinegatively charged ligand coordinating through the thiolo sulphur, the azomethine nitrogen and the hydroxyl oxygen. It forms mono-ligand complexes: [M(ONS)X], [M=Ni^II, Cu^II, Cr^III, Sb^III, Zn^II, Zr^IV or U^VI with X = H₂O, Cl]. The ligand produced a bis-chelated complex of composition [Th(ONS)₂] with Th^IV. Square-planar structures are proposed for the Ni^II and Cu^II complexes. Antimicrobial tests indicate that the Schiff base and five of the metal complexes of Cu^II, Ni^II, U^VI, Zn^II and Sb^III are strongly active against bacteria. Ni^II and Sb^III complexes were the most effective against Pseudomonas aeruginosa (gram negative), while the Cu^II complex proved to be best against Bacillus cereus (gram positive bacteria). Antifungal activities were also noted with the Schiff base and the U^VI complex. These compounds showed positive results against Candida albicans fungi, however, none of them were effective against Aspergillus ochraceous fungi. The Schiff base and its zinc and antimony complexes are strongly active against leukemic cells (CD₅₀ = 2.3–4.3 μg cm⁻³) while the copper, uranium and thorium complexes are moderately active (CD₅₀ = 6.9–9.5 μg cm⁻³). The nickel, zirconium and chromium complexes were found to be inactive. This revised version was published online in June 2006 with corrections to the Cover Date.     

New complexes of iron(III), cobalt(II), nickel(II) and copper(II) with 2-phenyl-1,2,3-triazole-4-carboxalidene-2-aminophenol

Summary Fe^III, Co^II, Ni^II and Cu^II complexes of a new Schiff base, 2-phenyl-1,2,3-triazole-4-carboxalidene-2-aminophenol (PTCAP), have been synthesized and characterized by elemental analyses, molar conductance and magnetic susceptibility measurements, and by u.v.-vis., i.r. and e.p.r. spectral observations. The studies indicate an octahedral structure for the complexes with the general formula [ML₂] (M = Co^II, Ni^II or Cu^II.; L = PTCAP) or [M′(OH)L₂] (M′ = Fe^III). The i.r. spectra suggest that the ligand acts as a tridentate (NNO) donor towards Co^II, Ni^II and Cu^II, and, in the Fe^III complex, one of the two ligand molecules acts as a bidentate (NO) donor and the other as a tridentate donor. The M?ssbauer spectrum of the Fe^III complex suggests the presence of a spin equilibrium at room temperature. Cyclic voltammograms are also recorded for the Cu^II and Fe^III complexes.     

Die elektrochemische Reduktion von CSSe und CSe2 in Dimethylformamid: Heterocyclische 1,2-Dichalkogenolate und ihre Koordinationschemie

Electrochemical Reduction of CSSe and CSe₂ in Dimethylformamide: Heterocyclic 1,2-Dichalcogenolates and their Coordination Chemistry Starting from carbon diselenide or carbon selenidesulfide the electrochemical preparation (electrosynthesis) of heterocyclic dichalcogenolates C₃X₅^2? (X = Se: dsis; X = S/Se: C₃S_xSe_y^2?) is outlined. The 1,2-dichalcogenolate compounds were isolated and characterized as dibenzoyl derivatives. Bis- or tris-chelates of general type A_m[M(C₃X₅)_n] (with A = Bu₄N⁺, Ph₄As⁺; M = Zn^II, Pt^II, Pd^II, Ni^III, Cu^III, Au^III, In^III; X = Se, S/Se; m = 1, 2, 3; n = 2, 3, respectively) are available directly from methanolic solutions of the dibenzoylates after hydrolytic cleavage of the latter with sodium methanolate. In addition bis-chelates Bu₄N[Ni(C₃X₅)₂] (X = Se, S/Se) have been characterized by cyclovoltammetry and epr spectroscopy and compared with the corresponding all-sulfur ligand compound Bu₄N[Ni(dmit)₂] (X = S). Arguments are given for the fact that the allselenium ligand dsis (X = Se) yields the Cu^III or Ni^III chelate at once whereas with dmit using identical conditions the metal(II) compounds are formed.     

Ligational behaviour of biacetylmonoxime nicotinoyl hydrazone (H2BMNH) towards transition metal ions

Summary The synthesis and characterization of Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II UO ₂ ²⁺ , Cr^III and Fe^III complexes of biacetylmonoxime nicotinoyl hydrazone (H₂BMNH) are reported. Elemental analysis, molar conductance, magnetic moment and spectral (i.r., visible and n.m.r.) measurements have been used to characterize the complexes. I.r. spectral data show that the ligand behaves in a bidentate and/or tridentate manner. An octahedral structure is proposed for the Mn^II, Ni^II, Cr^III and Fe^III complexes, while a square-planar structure is proposed for both Co^II and Cu^II complexes on the basis of magnetic and spectral measurements.     

Cobalt(III), copper(II), and nickel(II) complexes of 1-thia-4,7-diazacyclononane-S-oxide

Summary The title complexes [ML₂]ⁿ⁺=Co^III, Cu^II, Ni^II; L=1-thia-4,7-diazacyclononane-S-oxide) have been prepared and characterized spectroscopically. The sulphoxide group is coordinated through the oxygen atom and the complexes have atrans-O,O geometry. The nickel(II) complex of bis(2-amino-ethyl)sulphoxide has also been studied.     

The vibrational analysis of some oxamide complexes

Summary The vibrational spectra of the oxamide and deuteriooxamide complexes with Ni^II, Pd^II, Cu^II, Zn^II and Co^III are presented. The vibrational analysis is given for a planarD _2h structure for the Ni^II, Cu^II and Pd^II compounds; the Zn^II and Co^III complexes have a tetrahedral and octahedral structure respectively.Presented in part at the XIX I.C.C.C. Prague 1978.     

Supramolecular assemblies containing metallocyclam subunits

Abstract

The synthetic approach to supramolecular systems containing one or more metallocyclam subunits is reviewed. In particular, the template synthesis of azacyclam complexes has been used to design supramolecular coordination compounds displaying multi-electron redox activity. Moreover, it is shown that whenever the supramolecular design requires a component able to provide a fast and reversible redox change, a metallocyclam subunit should be used. Finally, the design of supramolecular systems in which a light-emitting fragment (anthracene) has been linked to a metallocyclam subunit has been considered. In particular, anthracene fluorescence can be switched on/off through the Cu^I/Cu^II redox couple inside a tetra-thia-macrocyclic environment, via an electron transfer mechanism.     

Studies on the stereochemistry of diphenyl diketone monothio-semicarbazone and its transition metal complexes

Summary The stereochemistry and complexation behaviour of diphenyl diketone monothiosemicarbazone (DKTS) with Cu^II, Co^II, Ni^II, Cd^II, Zn^II, Pd^II, Pt^II, Ru^III, Rh^III and Ir^III have been investigated by means of chemical, magnetic and spectral (i.r., Raman, ¹H- and ¹³C-n.m.r. and electronic) studies. The ligand forms complexes of the M(DKTS)₂ type with Ni^II, Cu^II and Co^II having a distorted octahedral geometry. The absence of a v(M—X) band in the i.r. spectra, coupled with their 1:1 electrolytic conductances, suggests that Ru^III, Rh^III and Ir^III form octahedral complexes of the [M(DKTS)₂]Cl type. A four-coordinate structure involving bridging halides is proposed for the Zn^II, Cd^II, Pd^II and Pt^II complexes, which have relatively low v(M—X) vibration modes.     

Polyazamacrocycles VIII. Polarographic behaviour of some tetraaza macrocyclic complexes of copper(II), nickel(II) and cobalt(III)

Summary The polarographic reduction at a dropping mercury electrode of several Cu^II, Ni^II and Co^III complexes of tetraaza macrocycles has been studied in 0.1M NaClO₄ as supporting electrolyte. The Cu^II complexes show values of half-wave potentials which can be correlated to the ring size and ligand field stabilisation. A similar, though less marked, trend is noticeable in the reduction of the Ni^II complexes. No such conclusions can be drawn in the case of the Co^III complexes.     

Coordination chemistry and biological activity of two tridentate ONS and NNS Schiff bases derived from S-benzyldithiocarbazate

Two tridentate Schiff bases having ONS and NNS donor sequences were prepared by condensing S-benzyldithiocarbazate (NH₂NHCSSCH₂Ph) (SBDTC) with pyridine-2-carboxaldehyde and salicylaldehyde, respectively. Complexes of these ligands with Ni^II, Zn^II, Cr^III, Co^II, Cu^II, and Sn^II were studied and characterized by elemental analyses and various physico-chemical techniques. Ni^II, Cu^II, Zn^II and Sn^II complexes were four-coordinate while the Cr^III, Sr^III and Co^III complexes were six-coordinate. The ONS Schiff base was moderately active against leukemia, while its zinc, antimony and cobalt complexes were strongly active against leukemic cells with DC₅₀ = 0.35–5.00.