F-metal Ions Research Articles

Ligand-controlled UV light absorption property and neuromorphic behavior of a new Th(IV)- bisphosphoramide complex

This article describes the synthesis and photophysical properties of a new furan-based bisphosphoramide ligand (L) and its Th(IV) complex characterized by various analytical and spectroscopic techniques. As expected, L, associated with several double bonds within the structure and the possible π → π* transitions, displays strong absorption in the UV region. Notably, the absorption of UV light decreases significantly in an exclusive manner for the L-Th4+ complex, and such behavior was not observed with most of the transition metals as well as f-metal ions. The ligand-to-metal binding ratio of L-Th4+ was found to be 1:1 through the Job’s plot. This photophysical property was successfully explored in the selective determination of Th4+ ions in aqueous solutions. The limit of detection (LOD) for Th4+ and limit of quantitation (LOQ) were determined to be 1.04 x 10-7 M and 3.472 x 10-7 M, respectively. In order to get an insight at the molecular level, a density functional theory (DFT) investigation was performed to comprehend the sensing mechanism and interaction in the detection of Th4+ by L. Furthermore, this salient UV light absorption phenomenon was employed in exploring the artificial synaptic behavior of the L-Th4+ complex which can have remarkable memory and applications in neuromorphic devices.

Chelation therapy-inspired design of a water-stable fluorescent probe for the effectual monitoring of copper(II) ions in real water.

This work introduces a thought-provoking design to develop a water-soluble chemical probe, sodium 4-hydroxy-3-((E)-((E)-((2-hydroxynaphthalen-1yl)methylene)hydrazono)methyl) benzenesulfonate (SW2) and its analytical characterization for the efficient detection and monitoring of Cu2+ ions in a matrix of s-, d-, and f-metal ions in pure water. The water-stable molecular probe, SW2, in the presence of Cu2+ salts in pure water exhibits a fluorescence turn-off characteristic with a high detection limit, 3.8 μM, and irresistibly holds 4-cycle reversibility in the presence of sulphide ions without any significant loss of its chemosensing efficiency. Spectroscopic and computational studies ensure 1 : 1 complexation between SW2 and Cu2+ ions, leading to the formation of SW2-Cu2+ chelate, thus inducing dynamic quenching of SW2 emission, which subsequently reverts on the addition of S2- ions in water. Additionally, the SW2-Cu2+ chelate was isolated in microcrystalline powder and the complexation was studied with mass spectrometry and EPR analysis. Computational analysis reveals the remarkable reduction in the S0-S1 energy level of the SW2-Cu2+ complex, which is attributed to the drastic quenching of the fluorescence intensity. Furthermore, SW2 was successfully applied to the detection of Cu2+ ions in tap and pond water. Interestingly, the probe is also effective for the determination of Cu2+ ions in the aqueous solution of a Cu-based fungicide (copper oxychloride), commercially available as Blitox in India, thus evaluating the effectiveness of SW2 in real sample analysis.

Expanding the Coordination of f-Block Metals with Tris[2-(2-methoxyethoxy)ethyl]amine: From Molecular Complexes to Cage-like Structures.

Low-valent f-block metals have intrinsic luminescence, electrochemical, and magnetic properties that are modulated with ligands, causing the coordination chemistry of these metals to be imperative to generating critical insights needed to impact modern applications. To this end, we synthesized and characterized a series of twenty-seven complexes of f-metal ions including EuII, YbII, SmII, and UIII and hexanuclear clusters of LaIII and CeIII to study the impact of tris[2-(2-methoxyethoxy)ethyl]amine, a flexible acyclic analogue of the extensively studied 2.2.2-cryptand, on the coordination chemistry and photophysical properties of low-valent f-block metals. We demonstrate that the flexibility of the ligand enables luminescence tunability over a greater range than analogous cryptates of EuII in solution. Furthermore, the ligand also displays a variety of binding modes to f-block metals in the solid state that are inaccessible to cryptates of low-valent f-block metals. In addition to serving as a ligand for f-block metals of various sizes and oxidation states, tris[2-(2-methoxyethoxy)ethyl]amine also deprotonates water molecules coordinated to trivalent triflate salts of f-block metal ions, enabling the isolation of hexanuclear clusters containing either LaIII or CeIII. The ligand was also found to bind more tightly to YbII and UIII in the solid state compared to 2.2.2-cryptand, suggesting that it can play a role in the isolation of other low-valent f-block metals such CfII, NpIII, and PuIII. We expect that our findings will inspire applications of tris[2-(2-methoxyethoxy)ethyl]amine in the design of light-emitting diodes and the synthesis of extremely reducing divalent f-block metal complexes that are of interest for a wide range of applications.

THEORETICAL AND EXPERIMENTAL APPROACHES IN THE STUDY OF ELECTROCHEMICAL AND THERMODYNAMIC PROPERTIES OF POLYFUNCTIONAL ORGANIC COMPOUNDS IN LIQUID-PHASE AND HETEROPHASE SYSTEMS

The publication reflects the experimental substantiation and fundamental development of some important ideas of the theory of the mutual influence of functional substitution in complex molecules of macrocyclic and chelating compounds on their coordination, solvation and redox properties, as well as the formation of algorithms for searching useful functions of these compounds. Researchers of the Analytical Chemistry Department of the Ivanovo State University of Chemistry and Technology have been studying the electrochemical and thermodynamic behavior of porphyrins, complexones, amino acids, peptides and the corresponding complexes with d- and f-metal ions, their influence on coordination, solvation and catalytic processes for a number of years. The results obtained together with the literature data are discussed in the review. For citation: Bazanov M.I., Berezina N.M., Gridchin S.N., Krutova O.N., Gorboletova G.G., Bychkova S.A., Lytkin A.I., Chernyavskaya N.V., Chernikov V.V., Volkov A.V. Theoretical and experimental approaches in the study of electrochemical and thermodynamic properties of polyfunctional organic compounds in liquid-phase and heterophase systems. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 7. P. 98-110. DOI: 10.6060/ivkkt.20236607. 6839j.

Discrete, Cationic Palladium(II)-Oxo Clusters via f-Metal Ion Incorporation and their Macrocyclic Host-Guest Interactions with Sulfonatocalixarenes.

We report on the discovery of the first two examples of cationic palladium(II)‐oxo clusters (POCs) containing f‐metal ions, [PdII 6O12M8{(CH3)2AsO2}16(H2O)8]4+ (M=CeIV, ThIV), and their physicochemical characterization in the solid state, in solution and in the gas phase. The molecular structure of the two novel POCs comprises an octahedral {Pd6O12}12− core that is capped by eight MIV ions, resulting in a cationic, cubic assembly {Pd6O12MIV 8}20+, which is coordinated by a total of 16 terminal dimethylarsinate and eight water ligands, resulting in the mixed PdII‐CeIV/ThIV oxo‐clusters [PdII 6O12M8{(CH3)2AsO2}16(H2O)8]4+ (M=Ce, Pd6Ce8 ; Th, Pd6Th8 ). We have also studied the formation of host‐guest inclusion complexes of Pd6Ce8 and Pd6Th8 with anionic 4‐sulfocalix[n]arenes (n=4, 6, 8), resulting in the first examples of discrete, enthalpically‐driven supramolecular assemblies between large metal‐oxo clusters and calixarene‐based macrocycles. The POCs were also found to be useful as pre‐catalysts for electrocatalytic CO2‐reduction and HCOOH‐oxidation.

Light-Emitting Lanthanide Periodic Mesoporous Organosilica (PMO) Hybrid Materials.

Periodic mesoporous organosilicas (PMOs) have a well ordered mesoporous structure, a high thermal and mechanical stability and a uniform distribution of organic functionalities in the pore walls. The organic groups allow PMOs to be modified and functionalized by using a wide range of organic reactions. Since their first report in 1999, PMOs have found a vast range of applications, such as for catalysis, adsorbents, low-k films, biomedical supports and also for optical applications. Optical applications are very interesting as PMOs offer the possibility of designing advanced luminescent hybrid materials comprising of organic components, yet with much higher stability and very good processability. Despite their promising possibilities, the optical properties of pristine PMOs and PMOs grafted with d-metal or f-metal ions and complexes have been explored less frequently. In this review, we aimed to overview the exciting light emitting properties of various reported lanthanide PMO hybrid materials and interest the reader in this promising application for lanthanide PMO materials.

Development of the Smartphone-Assisted Colorimetric Detection of Thorium by Using New Schiff's Base and Its Applications to Real Time Samples.

In this paper, a new Th4+ ion-selective chromogenic sensor (L) was developed by reacting 1,10-phenanthroline-2,9-dicarbohydrazide with 2-hydroxy naphthaldehyde. The sensing ability of L toward Th4+ was investigated in solution and paper strips loaded with L using spectrophotometric and colorimetric methods. The selective interaction of L was examined with various f-metal ions and other selected metal ions from s-block and d-block elements. Results show that by the colorimetric method in solution-phase dimethyl sulfoxide/H2O (7:3, v/v) and paper strip methods, the naked-eye detectable color change of L occurred from colorless solution to yellow-orange and pale yellow colour upon interacting with Th4+ and Al3+, respectively, whereas other metal ions did not interfere. The ligand L exhibits two absorbance bands at 320 and 375 nm because of ligand-to-ligand charge transfer. Upon interaction with Th4+, L undergoes red shift of both absorption bands and the formation of a new UV-vis band at 335 and 440 nm. The UV-visible spectral studies indicate the formation of a 1:1 host-guest complex between L and Th4+ with an association constant of 4.7 × 103 M-1. The limit of quantification and limit of detection of L for the analysis of Th4+ are found to be 167 and 50 nM, respectively. The visually detectable color change of L has been well integrated with a smartphone RGB color value to make it an analytical signal for real-time analysis of Th4+ with the detection limit down to 116 nM. Besides, L was applied for the analysis of Th4+ content present in various real water samples, monazite, and lantern mantle samples by spectrophotometry and RGB color values. The binding mode of L with Th4+ is investigated by 1H NMR, electrospray ionization-mass, and theoretical studies.

Quantum effects and magnetism in the spatially distributed DNA molecules

Electronic and magnetic properties of DNA structures doped by simple and transition d- and f-metal ions (Gd, La, Cu, Zn, Au) are reviewed. Both one- and two dimensional systems are considered. A particular attention is paid to gadolinium and copper doped DNA systems, their unusual magnetism being treated. The problem of classical and quantum transport (including transfer of genetic information during replication and transcription) and electron localization in biological systems is discussed.

Development of highly selective chemosensor for thorium estimation

A rapid and sensitive spectrophotometric method has been developed for the determination of Th4+ ions using tetra butyl 2,2′-bipyridine-5,5′-diylbis(methylene) diphosphonate (L) as a chemosensor. The selective complexation of L was examined with various f-metal ions like Th4+, U6+ and Ln's(III) ions and other selected metal ions (from s, p, and d-block elements). The chemosensor L selectively portrayed a naked-eye detectable colour change from colourless to pink with an appearance of a new charge transfer band at 320nm and 525nm. No noticeable spectral and colour changes of L were observed with other tested metal ions. This confirms high selectivity of L towards Th4+ ions. The Job’s plot delineated the formation of a host–guest complex between L and Th4+ in 1:1 binding stoichiometry. The binding constant for the complexation of L-Th4+ was calculated from Benesi–Hildebrand (BH) plot and was found to be 6×103M−1. The complexing ability L with Th4+ was supported by 31P NMR, FT-IR, UV-DRS, vibrating sample magnetometery and mass spectral data. The limit of detection (LOD) and limit of quantification (LOQ) of L for the analysis of Th4+ was calculated to be 2.02μM and 6.1μM, respectively. Finally, the chemosensor L was successfully applied for the quantification of Th4+ contents present in monazite sand, gas mantels and different water samples.

ChemInform Abstract: Lanthanide‐Directed Synthesis of Luminescent Self‐Assembly Supramolecular Structures and Mechanically Bonded Systems from Acyclic Coordinating Organic Ligands

AbstractReview: 232 refs.

Lanthanide-directed synthesis of luminescent self-assembly supramolecular structures and mechanically bonded systems from acyclic coordinating organic ligands.

Herein some examples of the use of lanthanide ions (f-metal ions) to direct the synthesis of luminescent self-assembly systems (architectures) will be discussed. This area of lanthanide supramolecular chemistry is fast growing, thanks to the unique physical (magnetic and luminescent) and coordination properties of the lanthanides, which are often transferred to the resulting supermolecule. The emphasis herein will be on systems that are luminescent, and hence, generated by using either visibly emitting ions (such as Eu(III), Tb(III) and Sm(III)) or near infrared emitting ions (like Nd(III), Yb(III) and Er(III)), formed through the use of templating chemistry, by employing structurally simple ligands, possessing oxygen and nitrogen coordinating moieties. As the lanthanides have high coordination requirements, their use often allows for the formation of coordination compounds and supramolecular systems such as bundles, grids, helicates and interlocked molecules that are not synthetically accessible through the use of other commonly used templating ions such as transition metal ions. Hence, the use of the rare-earth metal ions can lead to the formation of unique and stable species in both solution and in the solid state, as well as functional and responsive structures.

Synthesis and properties of 2-azahetarylaminomethylidene 1,3-dicarbonyl compounds

Reactions of 2-ethoxymethylidene 1,3-dicarbonyl compounds with pyridine-2,6- and pyrimidine-4,5-diamines gave the corresponding 2-hetarylaminomethylidene derivatives. Depending on the initial reactant structure, the formation of mono-and/or bis-condensation products is possible. Hetarylaminomethylidene derivatives showed a moderate tuberculostatic effect. 2-Pyridinylaminomethylidene 3-oxo esters were used as ligands to obtain coordination compounds with d- and f-metal ions.

Complexation studies of 3-substituted β-diketones with selected d- and f-metal ions

AbstractResults of spectroscopic investigations related to complex compositions of 3-substituted derivatives of pentane-2,4-dione (β-diketonate) complexes with chosen d- and f-metal ions are presented. Ligands 3-allylacetylacetone (3all-acac) and 3-benzylacetylacetone (3ben-acac) were prepared and used for the complexation study with Cu(II), Co(II), Nd(III), and Ho(III) metal ions. Based on the absorption spectra of lanthanide ions in their hypersensitive transitions, with the use of computer assisted target factor analysis (CAT) and absorption spectra of the ligands with Cu(II) and Co(II), the verification of complex compositions and the determination of their stability constants were achieved. In case of Nd(III) and Ho(III) complexes with β-diketone ligands, absorption of their maxima were studied in the range of hypersensitive transitions 4 I 9/2 → 4 F 7/2 + 4 S 3/2 (λ max ∼ 734 nm and 748 nm) for Nd(III) and in the range of 435–465 nm, corresponding to the hypersensitive transition 5 G 6 → 5 I 8 (λ max ∼ 450 nm), for Ho(III).

Mixed d−f3 Coordination Complexes Possessing Improved Near-Infrared (NIR) Lanthanide Luminescent Properties in Aqueous Solution

The cyclen-based ligand 1, possessing a [1,10]-phenanthroline moiety as a pendant arm, has been used as a ditopic ligand for the complexation of d- and near infrared (NIR) emitting (and) f-metal ions. This ligand forms kinetically stable complexes, 1·Ln, with lanthanide ions such as Ln = ytterbium, neodymium, and lutetium (formed as a non-IR emitting reference compound), the synthesis and photophysical properties of which are described herein in detail. These 1·Ln complexes were then used as building blocks for the formation of mixed d−f heteropolymetallic self-assemblies, where the phen moiety was used to complex a ruthenium (Ru(II)) ion, giving the d−f3 complexes Ru·Ln3 (Ln = Nd(III), Yb(III), Lu(III)). The formation of these supramolecular coordination conjugates was studied by using absorption and luminescence spectroscopy, while the solution structure of the Ru·Lu3 was elucidated by 1H NMR in D2O and H2O. Of these conjugates, both Ru·Nd3 and Ru·Yb3 displayed an intense NIR-emission in H2O at pH 7.4 (with Q(Yb)(L) = 0.073% and Q(Nd)(L) = 0.040%) and in D2O (with QYbL = 0.23% and Q(Nd)(L) = 0.10%). By comparison with their monometallic analogues Ln·1 (Ln = Nd(III), Yb(III)), we demonstrate that our new design possesses an enhanced sensitization efficiency for lanthanide metal centered sensitization upon using the [Ru(phen)3] moiety (d → f energy transfer) as a visibly exciting antenna, and we demonstrate that the intensity of the Ru(II)-based luminescence strictly correlates to the efficiency of the d → f energy transfer processes.

Synthesis, IR and NMR characterization and ion extraction properties of tetranonylcalix[4]resorcinol bearing acetylhydrazone groups

A series of new calix[4]resorcinarenes ( rccc-isomer) and resorcinols functionalized by acetylhydrazone binding fragments have been synthesized. The IR and NMR data and stereochemical behaviour of hydrazones are reported and compared with the results of earlier investigations. The barriers of rotation of hydrazone fragments for some octahydrazone derivatives of calix[4]resorcinarenes and their resorcinol analogues have been determined by NMR-measurements. The complexing behaviour of bis- and octahydrazones has been studied by liquid–liquid extraction towards the s-metal ions (Li +, Na +, K +, Cs + and Ca 2+), p-metal ions (Pb 2+), d-metal ions (Co 2+, Ni 2+, Cu 2+, Zn 2+, Cd 2+ and Hg 2+) and f-metal ions (La 3+, Gd 3+ and Lu 3+). The stoichiometry of complexes and the extraction constants have been determined. It has been established that octahydrazones do not extract alkali metal cations but show excellent selectivity towards transition and soft heavy metal cations (especially Hg 2+ or Pb 2+).

Multiplets of free d- and f-metal ions: A systematic DFT study

In this work we apply in a systematic way our multi-determinantal model to calculate the fine structure of the whole atomic multiplet manifold. The key feature of this approach is the explicit treatment of near-degeneracy correlation using ad hoc configuration interaction (CI) within the active space of Kohn–Sham (KS) orbitals with open d- or f-shells. The calculation of the CI-matrices is based on a central symmetry decomposition of the energies of all single determinants (micro-states) calculated according to Density Functional Theory (DFT) for frozen KS-orbitals corresponding to the averaged configuration, eventually with fractional occupations, of the d- or f-orbitals and/or the direct calculation of the electrostatic reduced matrix elements (Racah or Slater–Condon parameters) occurring in the corresponding active space. We performed DFT calculations on all divalent and trivalent d 2–d 8 metal ions, as well as the f 2–f 12 lanthanide(III) ions. We compare the results of both variants of the method with the data available in the literature. Both procedures yield multiplet energies with an accuracy of about hundred wave numbers and fine structure splitting accurate to less than a tenth of this amount.

Asymmetric compartmental macrocyclic ligands and related mononuclear and hetero-dinuclear complexes with d- and/or f-metal ions

[1+1] Asymmetric compartmental macrocycles H 2L (H 2L A–H 2L G), containing one N 2O 2, N 3O 2 or N 2O 2O 2 Schiff base and one adjacent O 2O 3, O 2O 4 or O 2O 5 ‘crown like’ coordination chamber, have been prepared by self-condensation or by reaction of the appropriate diformyl (H 2L I–H 2L III) and amine precursors in the presence of barium(II) salts, followed by a demetallation reaction of the resulting complexes, Ba(H 2L)(ClO 4) 2, with guanidinium sulphate. They have been characterised by IR, NMR and mass spectrometry. The single crystal X-ray structural determination of H 2L C confirms their [1+1] cyclic nature. The mononuclear complexes Ln(H 2L)(X) 3· nS (Ln=La-Lu; X=Cl −, NO 3 −) and Ni(L)· nS have been prepared by reaction of the preformed ligands with the appropriate metal salt, by template procedure or by condensation of the acyclic complexes with the diformyl derivatives Ln(H 2L′)(X) 3 or Ni(L′) with the appropriate amine. They have been characterised by IR, NMR, magnetic susceptibility and mass spectrometry. In these mononuclear complexes the 4f and transition metal ion invariantly occupy respectively, the crown-like and the Schiff base chamber. In [La(H 2L C)(H 2O) 4]Cl 3 the single crystal X-ray structure reveals that a bicapped square antiprismatic decacoordination about the central metal ion is reached by the coordination of the oxygen atoms of the crown-ether chamber and by the oxygen atoms of four water molecules. A Schiff base occupancy has been obtained by the lanthanum ion only when Ba(H 2L)(ClO 4) 2 was used instead of the free ligand H 2L: the barium ion remains in the crown-ether chamber and obliges the incoming lanthanum ion to fill the Schiff base site. By this procedure the hetero-dinuclear complex, LaBa(L D)(ClO 4) 2(OH)·3H 2O, has been obtained. La(H 2L C)(Cl) 3, by reaction with the appropriate metal salt, gives rise to the hetero-dinuclear species MLa(L C)(Cl) 2(OH)· nH 2O (M=Cu, n=1; M=Ni, n=2). LaNa(L D)(X) 2·(X=Cl, NO 3) and LaNa(L F)(NO 3) 2 have been synthesised by template procedure or by reaction of H 2L D or H 2L F with the appropriate lanthanum(III) salt and sodium hydroxide.

Functionalized acyclic Schiff bases and related complexes with d- and f-metal ions

The condensation reaction in acetonitrile of 2,6-diformyl-4-chlorophenol with tris-(2-aminoethyl)amine forms the [3+1] macroacyclic Schiff base H 3-I which reacts with LnCl 3·n nH 2O (Ln = La 3+, Dy 3+, Gd 3+) in the presence of Net 3 giving rise to Ln( I)· nS (S = H 2O, dmf, CH 3CN: n=0–1.5). Crystals of La( I) (dmf), grown from a dimethylformamide/acetonitrile solution, are monoclinic, space grop P2 1/c with a = 12.590(4), b = 14.277(5), c = 19.710(5)Å, β=95.45° and Z = 2. This complex is a dimeric entity and shown an inversion center in between the two lanthanum(III) ions. The organic ligand coordinates to one lanthanum ion through the four nitrogen and the three phenoxide oxygen atoms while it links the second lanhanum ion through one aldehydic oxygen atom: the other two aldehydic oxygens are not involved in the coordination and do not form significative interactions with neighboring molecules. Thus each dinuclear complex behaves as an isolated entity. The nonacoordination around each metal ion is reached through the additional coordination of the oxygen atom of a dimethylformamide molecule. The three LaN (iminic) bond distances fall between 2.70 and 2.79 Å, while the LaN (aminic) bond is longer (2.86 Å). Similarly the LaO (phenolic) bonds distances are in the range 2.41–2.47 Å, considerably shorter than the LaO (aldehydic) which is 2.72 Å, while the LaO (dimethylformamide) is 2.55 Å. Finally the two lanthanum atoms are 8.24 Å apart. 2,6-Diformyl-4-chlorophenol reacts in CH 4CN with H 2NRNH 3 to give the [2 + 1] acyclic Schiff bases H 2-II . The corresponding complexes containing a d (nickel(II) Ni( II), or manganese(III) Mn( II)(OH), and (lanthanum(III), gadohnium(III), dysprosium(III)) Ln( H 2-II )(NO 3) 4 or the uranyl(VI) ion, UO 2( II)(MeOH), UO 2( H-II)(NO 4) and UO 2( H 2-II )(NO 4) 2 have also been prepared by reaction of these ligands with the appropriate metal salts or by template procedure, the different content of the nitrate in the uranyl(VI) complexes depending on the amount of base used. These complexes may be converted into the acetal analogues in alcoholic solution. Similarly the condensation of 3-methoxy-2-hydroxybenzaldehyde or 3-ethoxy-2-hydroxybenzaldehyde with tris-(2-aminoethyl)amine in a 1:3 molar ratio afforded Schiff bases H 3-IV and H 3-V which react with lanthanide(III) salt to give rise, respectively, in the presence or in the absence of the appropriate amount of base, to Ln( IV)· nH 2O and Ln( V)· nH[in2O and Ln( H 3-IV )(X) 4 ·n nH 2O or Ln( H 3-V ) (X) 3· nH 2O (Ln=La 3+, Gd 3+; X=Cl, NO 4 6; n = 1–5. These complexes are no longer stable in solution and hydrolyzed especially when redissolved in alcohol. H 3-I , H 2-II and/or the related complexes have been engaged in further condensation reactions with 2-aminomethyl-12-crown-4 or 2-aminomethyl-15-crown-5 to give rise to the functionalized Schiff bases ( H 3-III and H 2-VII ) and related d- or f-complexes. Moreover the functionalized ligands H 3-VI, H 2-VIII, H 2-X and H 2-XI and/or the related d- or f-complexes have been synthesized by condensation of the appropriate formyl and amine precursors. The ligands and the complexes have been characterized by physico-chemical measurements, especially by IR and NMR spectroscopy, SEM and EDX investigation, and FAB mass spectrometry.

Preparation, properties and X-ray structure of a cyclic compartmental Schiff base and related complexes containing d- or f-metal ions

A new compartmental ligand (H 2L A) containing an N 2O 2 Schiff base and an O 2O 4 `crown like' coordination site has been prepared by reaction of 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)bis(2-hydroxybenzaldehyde) with ethylenediamine and the [1+1] cyclic nature was confirmed by its X-ray single crystal structural determination. When reacted with d- or f-metal ions, H 2L A forms mononuclear complexes where the metal ion coordinates respectively the N 2O 2 or the O 2O 4 chamber. The X-ray structure of [La(H 2L A)(H 2O) 4]Cl 3 shows the ten-coordination about the metal ion is reached by the six oxygen atoms of the compartmental ligand and by the oxygen atoms of four water molecules; the chloride atoms are ionic.

Novel Schiff base compounds containing calix[4]arene

New cyclic and acyclic Schiff bases have been prepared by condensation reaction of 5,17-diamino-25,26,27,28-tetrapropoxycalix[4]arene (L B) with 2,6-diformyl-4-chlorophenol and 1,5-diamino-3-aza(methyl)pentane or with 2,3-dihydroxybenzaldehyde. The related complexes containing d- or f-metal ions have been obtained by reaction of the preformed ligands with the appropriate metal salt or by a template macrocyclic synthesis. The hetero-polynuclear complexes have been synthesized by a step by step procedure. Condensation of 5,17-diformyl-25,27-dipropoxycalix[4]arene (L A) with tris(2-aminoethyl)amine affords a macrobicyclic ligand containing three calixarene units. The ligands and the related complexes have been characterized by elemental analyses, IR or NMR spectroscopy and mass spectrometry. The stoicheiometries of the complexes have been assigned by SEM and EDX investigations.