Hexaaza Macrocycle Research Articles

High Durability of a 14-Membered Hexaaza Macrocyclic Fe Complex for an Acidic Oxygen Reduction Reaction Revealed by In Situ XAS Analysis.

Nonplatinum metal (NPM) catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) have been developed; however, NPM catalysts still need to be improved in terms of both their catalytic activity and durability. To overcome these problems, an Fe active site contained within a more compact ligand than conventional, porphyrinic, 16-membered ring ligands, or more specifically, a hexaaza macrocyclic ligand with a 14-membered ring (14MR), was developed. In this study, the durability of the Fe-14MR complex was compared to that of Fe phthalocyanine (FePc), which has a 16-membered ring ligand, using in situ X-ray absorption spectroscopy; demetalation of the Fe complexes was directly observed during electrochemical experiments performed under acidic ORR conditions. It was found that Fe-14MR is significantly more resistant to demetalation than FePc during the ORR.

Carbonate-bridged dinuclear lanthanide(III) complexes of chiral macrocycle

Mononuclear Eu(III) and Dy(III) complexes of the chiral hexaaza macrocycle L, 2(R),7(R),18(R),23(R)-1,8,15,17,24,31-hexaazatricyclo[25.3.1.1.0.0]-dotriaconta-10,12,14,26,28,30-hexaene have been obtained as chloride derivatives (1 and 2, respectively) and characterized by using spectroscopic methods. The X-ray crystal structure of 2 has been determined. The reaction of two equivalents of mononuclear 1 or 2 complexes with one equivalent of sodium carbonate results in the formation of dinuclear complexes [Eu2L2(µ2-CO3)(H2O)3]Cl43 and [Dy2L2(µ2-CO3)(H2O)3]Cl44, respectively. The X-ray crystal structure of complex 3 reveals two macrocyclic [EuL]3+ units bridged by the carbonate anion. The carbonate anion is bound to the Eu(III) ions using the η1:η2-µ2 bridging mode. The binding of carbonate anions to the [EuL]3+ or [DyL]3+ macrocyclic units has also been studied in solution using spectroscopic methods. The titration of the starting paramagnetic mononuclear chloride derivatives 1 and 2 monitored by 1H NMR spectroscopy revealed initial formation of dinuclear species, followed by the formation of complexes possessing additional carbonate ligands. The dinuclear carbonate complexes 3 and 4 are also formed in the reactions of the respective mononuclear chloride complexes with gaseous CO2. Lanthanide(III) complexes of the chiral hexaaza macrocycle L are effective for catalytic hydrolysis of bis(4-nitrophenyl) phosphate BNPP. Within the series of the studied mononuclear complexes: nitrate derivatives [LnL(NO3)(H2O)](NO3)2 (Ln = Ho, Er), [LnL(H2O)2](NO3)3 (Ln = Tm, Yb, Lu) and chloride derivatives [LnL(H2O)2]Cl3 (Ln = Tm, Yb, Lu, Y) the catalytic activity of the complexes is increased with increasing ionic size. Kinetic studies revealed that most active is the dinuclear europium(III) complex 3 which catalyzes the hydrolysis of BNPP with a rate kobs = 6.5 × 10−5 s−1 (at 0.3 mM concentration of the catalyst) at pH 8.5 and 37 °C.

14-Membered cyclic bis-semicarbazones: Stereoselective synthesis and structural features

Stereoselectivity of acid-catalyzed cyclization of 4-(1-aryl-3-oxobutyl)semicarbazide hydrazones into mixtures of trans- and cis-isomers of 14-membered cyclic bis-semicarbazones has been studied. The isomer ratio is dependent on solvent, catalyst acidity, substrate structure and concentration, reaction temperature and time, catalyst loading. The experimental data show that the macrocyclization of acyclic precursors initially formed from two molecules of substrates proceeds with low diastereoselectivity to give mixtures of trans- and cis-macrocycles followed by slow transformation of cis-isomers into trans-isomers via ring opening by a retro-aza-Michael reaction resulting in high trans-selectivity. The driving force of this isomerization is shown to be a lower solubility of trans-isomers compared with cis-isomers. Some mechanistical aspects of the macrocycle formation were confirmed by calculations performed at the DFT B3LYP/6–311++G(d,p) level of theory. Molecular structure of the obtained hexaaza macrocycles was established using single crystal and powder X-ray diffraction, IR, UV–Vis, 1H and 13C NMR spectroscopy, and DFT calculations.

An efficient and stereoselective approach to 14-membered hexaaza macrocycles using novel semicarbazone-based amidoalkylation reagents

An efficient synthesis of hydrazones of 4-(3-oxobutyl)semicarbazides and 4-(3-oxobutyl)semicarbazones using novel semicarbazone-based amidoalkylation reagents, 1-arylidene-4-[(aryl)(tosyl)methyl]semicarbazides, has been developed. The synthesis involved reaction of the latter with the Na-enolate of acetylacetone, followed by a base-promoted retro-Claisen reaction and treatment of the obtained 4-(3-oxobutyl)semicarbazones with hydrazine or methylhydrazine. The prepared hydrazones were converted stereoselectively into 14-membered cyclic bis-semicarbazones under acidic conditions. Especially high selectivity (trans/cis⩾97:3) was observed upon the macrocyclization of 4-(3-oxobutyl)semicarbazone hydrazones. A plausible reaction pathway and the stereochemistry of this cyclization were discussed.

Synthesis, characterization, antibacterial activities and theoretical studies of Mn(II) and Cd(II) complexes with new macrocyclic Schiff base ligands incorporating a phenanthroline head unit

Three new hexaaza (N6) macrocyclic Schiff base ligands containing a phenanthroline moiety (L1-L3) have been synthesized and their coordination capability toward perchlorate salts of Mn(II) and Cd(II) have been investigated. The complexes are 18- and 19-membered hexaaza macrocycles, and incorporate a 1,10-phenanthroline unit as an integral part of their cyclic structure. All complexes have been characterized by a variety of methods such as IR, elemental analysis, EI-Mass, and conductivity measurements and in the case of cadmium complexes by 1H and 13C NMR spectroscopy. DFT (BP86) calculation on structures and molecular orbital of Mn(II) and Cd(II) complexes of latter ligands are also reported. Also the synthesized complexes were screened for their antibacterial activities against six bacterial strains and showed antibacterial effects.

Antibacterial, DNA interaction and cytotoxic activities of pendant-armed polyamine macrocyclic dinuclear nickel(II) and copper(II) complexes

A series of dinuclear nickel(II) and copper(II) complexes (1–6) of hexaaza macrocycles of 2,6-diformyl-4-methylphenol with three different benzoyl pendant-arms, 2,2′-benzoyliminodi(ethylamine) trihydrochloride (L), 2,2′-4-nitrobenzoyliminodi(ethylamine) trihydrochloride (L′) and 2,2′-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride (L″) have been synthesized and characterized by spectral methods. The electrochemical studies of these complexes depict two irreversible one electron reduction processes around E1pc=−0.62 to −0.76V and E2pc=−1.21 to −1.31, and nickel(II) complexes (1–3) exhibit two irreversible one electron oxidation processes around E1pa=1.08 to 1.14V and E2pa=1.71 to 1.74V. The room temperature magnetic moment values (μeff, 1.52–1.54 BM) indicate the presence of an antiferromagnetic interaction in the binuclear copper(II) complexes (4–6) which is also observed from the broad ESR spectra with a g value of 2.14–2.15. The synthesized complexes (1–6) were screened for their antibacterial activity. The results of DNA interaction studies indicate that the dinuclear complexes can bind to calf thymus DNA by intercalative mode and display efficient cleavage of plasmid DNA. Further, the cytotoxic activity of complexes 2, 5 and 6 on human liver adenocarcinoma (HepG2) cell line has been examined. Nuclear-chromatin cleavage has also been observed with PI staining and comet assays.

The synthesis, crystal structures and antimicrobial studies of C‐methyl‐substituted hexaaza macrocycle of Cu(II) having aromatic pendant arm

AbstractCu(II) complexes of 14‐membered hexaaza macrocyclic ligand with C‐methyl substituent of the type [CuL](X)2 (where L = 3,10‐bisbenzyl‐6,13‐dimethyl‐1,3,5,8,10,12‐hexaazacyclotetradecane, and X = ClO4−, PF6−) were synthesized by tandem reaction. They were characterized by spectral and single‐crystal X‐ray diffraction techniques. The complexes show distorted octahedral geometry and the counter ions are weakly coordinated to the metal ion at the axial positions. The macrocyclic ring adopts the trans‐III configuration with six‐ and five‐membered chelate rings in chair and gauche conformation, respectively. It was observed that in the solid state the arrangement of the coordination sphere is distorted octahedral whereas, in solution, a square‐planar structure is predominant. The molar conductance of the complexes indicates that the axially bonded anions are almost dissociated in acetonitrile solution. The Electron Paramagnetic Resonance (EPR) spectrum of complex 1 is axial and consistent with a dx2 − y2 ground state. The [CuL](ClO4)2 was found to be active against the tested microorganism. Copyright © 2011 John Wiley & Sons, Ltd.

Synthesis and characterization of 18- and 20-membered hexaaza macrocycles containing pyridine manganese(II) complex nanoparticles dispersed within nanoreactors of zeolite-Y

Manganese(II) complexes of [18]py 2N 4: 3,6,14,17,23,24-hexaazatricyclo[17.3.1.1 8,12]tetracosa-1(23),2,6,8(24),9,11,13,17,19,21-decane; [20]py 2N 4: 3,7,15,19,25,26-hexaazatricyclo[19.3.1.1 9,13]hexacosa-1(25),2,7,9(26),10,12,14,19,21,23-decaene; Bzo 2[18]py 2N 4: 3,10,18,25,31,32-hexaazapentacyclo[25.3.1.1. 12,16.0 4,9.0 19,24]dotriaconta 1(31),2,4(9),5,7,10,12(32),13,15,17,19,21,23,25,29-hexadecane and Bzo 2[18]py 2N 4: 2,10,16,24,30,32-hexaazapentacyclo[23.3.1.1 4,8.1 1,1,151 18,22otriaconta-1(29),2,4,6,8(32),9,11,13,15(31),16,18(30),19,21,23,25,27-hexadecane have been encapsulated in the nanopores of zeolite-Y by the template condensation reaction. Mn(II) complexes with macrocyclic ligand were entrapped in the nanocavity of zeolite-Y by a two-step process in the liquid phase: (i) the adsorption of [bis(diamine)manganese(II)]; [Mn(diamine) 2] 2+@NaY; in the supercages of the zeolite, and (ii) in situ condensation of the manganese(II) precursor complex with 2,6-diacetylpyridine. The new complex nanoparticles entrapped in the nanoreactor of zeolite-Y have been characterized by FT-IR, diffuse reflectance (DRS), X-ray photoelectron (XPS), thermal analysis, UV–Vis spectroscopic techniques, X-ray diffraction (XRD) and elemental analysis as well as by nitrogen adsorption.

Synthesis and characterization of three novel manganese(II) octaaza macrocyclic Schiff base complexes containing a phenanthroline and two pyridyl units as pendant arms. X-ray crystal structure determination of one manganese(II) complex

Three new branched hexadentate amines (N 6), 3,6-bis(2-pyridylmethyl)-3,6-diazaoctane-1,8-diamine ( 1), 3,7-bis(2-pyridylmethyl)-3,7-diazanonane-1,9-diamine ( 2) and 3,8-bis(2-pyridylmethyl)-3,8-diazadecane-1,10-diamine ( 3) have been synthesized. Subsequently, three novel Schiff base macrocyclic complexes containing a phenanthroline and two 2-pyridylmethylpendant arms have been prepared by template [1+1] cyclocondensation of 2,9-dicarboxaldehyde-1,10-phenanthroline and the branched hexadentate amines ( 1– 3), in the presence of Mn(II) in methanol. These complexes have ligands with 18-, 19- and 20-membered hexaaza macrocycles and two 2-pyridylmethyl pendant arms (L 1, L 2 and L 3, respectively). All the complexes have been characterized by elemental analysis and IR spectroscopy. The crystal structure of [MnL 1](ClO 4) 2 · 3CH 3CN was determined and indicates that in the solid state the complex adopts a slightly distorted hexagonal bipyramidal geometry with the Mn(II) ion located within a hexaaza macrocycle with the two 2-pyridylmethyl pendant arms coordinating in axial positions.

Template synthesis and characterization of hexaaza macrocycles containing pyridine iron(II) complex nanoparticles dispersed within nanoreactors of zeolite-Y

Iron(II) complexes with 18- and 20-membered hexaaza macrocyclic ligands were entrapped in the nanoreactors of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(diamine)iron(II)] (diamine = 1,2-diaminoethane, 1,3-diaminopropane, 1,2-diaminobenzene, 1,3-diaminobenzene); [Fe(N–N) 2] 2+–NaY; in the nanoreactors of the zeolite, and (ii) template condensation of the iron(II) precursor complex with 2,6-diacetylpyridine.The mode of bonding and overall geometry of the complexes and new complex nanoparticles entrapped in the nanoreactor of zeolite-Y ([Fe([18 or 20]py 2N 4)] 2+–NaY, [Fe(Bzo 2[18 or 20]py 2N 4)] 2+–NaY) has been inferred through FT-IR, TGA, XRD, XPS spectroscopic techniques and elemental analysis as well as nitrogen adsorption.

Electrochemical Behavior of Ascorbic Acid on Hexaaza Macrocyclic Copper(II) Complex Modified Au Electrode and Its Analytical Application

AbstractA novel hexaaza macrocyclic copper(II) complex modified Au electrode was developed and used for the measurement of ascorbic acid. Its electrochemical behavior was investigated by cyclic voltammetry and scanning electrochemical microscopy. This modified electrode exhibited electrocatalytic response to the oxidation of ascorbic acid. Compared with a bare gold electrode, the modified electrode exhibited a 250 mV shift of the oxidation potential of ascorbic acid in the cathodic direction and a marked enhancement of the current response. The response current revealed a good linear relationship with the concentration of ascorbic acid in the range of 5.0×10−7 to 4.0×10−5 mol/L and the detection limit of 4.8×10−8 mol/L (S/N=3) in the pH 4.0 Tris‐HCl buffer of ascorbic acid in fruits without any other pretreatment. The concentrations of ascorbic acid measured by this method were in good agreement with the literature values. It is very promising for the modified electrode to be used as an electrochemical sensor for the detection of ascorbic acid.

Macrocyclic nickel(II) and copper(II) complexes of the deca- and tetradecaaza ligands

Template condensation reactions between the dinuclear nickel(II) or copper(n) complexes of the hexaaza macrocycles 1,4,7,9,12,15-hexaaza-8,8,16,16-tetrachlorocyclohexadecane (HTCH) or 1,4,7,10,13,16-hexaaza-8,9,17,18-tetrachlorocyclooctadecane (HTCO) and triethylenetetramine have yielded products of three new macrocyclic ring systems : 1,4,7,10,12,15,18,20,23,26,29,30,33,36-tetradecaazadispiro[10.7.10.7]hexatriacontane (TDSH), 2,5,8,11,14,17,19,22,25,28-decaaza-9,10-dichlorobicyclo[16.10.0]octacosane (DDCO) and 2,5,8,10,13,16,19,21,24,27,29,32,35,38-tetradecaazatricyclo[26.10.0.0 9,20 ]octatriacontane (TTCO). Formulation of these products as [Ni 4 (TDSH)(H 2 O) 10 ]Cl 8 .5H 2 O, [Cu 4 (TDSH)-(H 2 O) 2 ]Cl 8 , [Ni 3 (DDCO)(H 2 O) 8 ]Cl 6 and [Ni 4 (TTCO)(H 2 O) 10 ]Clg and the metal-free TDSH.14HCl has been supported by elemental analyses, conductivity measurements, melting points and spectroscopic studies.

Fine-Tuning Ligand−Receptor Design for Selective Molecular Recognition of Dicarboxylic Acids

The host-guest interaction between the hexaaza macrocyclic ligand 3,7,11,18,22,26-hexaazatricyclo[26.2.2.2]tetratriaconta-1(31),13(34),14,16(33),28(32),29-hexaene (P3) and three rigid dicarboxylic acids (isophthalic acid, H2is; phthtalic acid, H2ph; and terephthalic acid, H2te) has been investigated using potentiometric equilibrium methods and NMR spectroscopy including the measurement of intermolecular nuclear Overhauser effects (NOEs) and self-diffusion coefficients (D). Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic interactions between the host and the guest. In the [(H6P3)(is)]4+ complex, those bonding interactions reach a maximum yielding a log K6R of 4.74. Competitive distribution diagrams and total species distribution diagrams are used to illustrate the main features of these systems. In particular, a selectivity of over 89% at p[H] = 5.0 is obtained for the complexation of the is versus the te substrates. The recognition capacity of P3 over dicarboxylic acids (da) is compared to the related hexaaza macrocycle Me2P3 (7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2]tetratriaconta-1(30),13,15,28,31,33-hexaene) that binds da with a lesser strength, and it is not selective. Theoretical calculations performed at molecular dynamics level have also been carried out and point out that the origin of selectivity is mainly due to the capacity of the P3 ligand receptor to adapt to the geometry of the dicarboxylic acid to form relatively strong hydrogen bonds.

New macrocyclic Schiff-base complexes incorporating a phenanthroline unit. Part 2: Template synthesis of some manganese(II) complexes and crystal structure studies

A series of Mn(II) macrocyclic Schiff-base complexes [MnL n ] 2+ have been prepared via the Mn(II) templated [1+1] cyclocondensation of 2,9-dicarboxaldehyde-1,10-phenanthroline with appropriate linear and branched amines. In this way ligands the pentaaza macrocycle L 1 which is 15-membered and L 2 which is 16-membered possessing no pendant arm, L 6 is 15-membered with one 2-aminoethyl pendant arm and L 8 which is 18-membered hexaaza macrocycle with two 2-aminoethyl pendant arms are formed. All the complexes have been characterized using spectroscopic methods. The crystal structures of [MnL 8](ClO 4) 2 · EtOH were determined and indicate that in the solid state the complex adopts a slightly distorted hexagonal bipyramid geometry with the Mn(II) ion located within a hexaaza macrocycle with the two pendant amines coordinating in the axial positions.

Oxidative Dehydrogenation of Hexaaza Macrocyclic Nickel(II) Complexes Bearing Two N-Alkyl Pendant Arms: Preparation of New Complexes Containing Imidoylamidine Linkages

Metal-promoted reactions of coordinated organic compounds, such as oxidative dehydrogenation reactions, have attracted particular attention because of their potential applications in organic chemistry, catalysis, and biochemistry. The saturated tetraaza macrocyclic nickel(II) complex [NiL] is known to react with HNO3 to yield [NiL] containing four isolated imino groups. The reaction of [NiL] with HNO3 produces [NiL] and [NiL] containing only one or two imino groups in the six-membered chelate ring(s). On the other hand, [NiL] reacts with H2O2 to produce the dinuclear complex [Ni2L], in which two unsaturated macrocyclic units are linked together by a C=C bond. Literature up to date clearly shows that the number and position of the imino groups in the product is strongly influenced by the structural characteristics of the macrocycle. In this work, we attempted the oxidative dehydrogenation of the hexaaza macrocyclic complexes [NiL] and [NiL] bearing two N-alkyl groups and prepared [NiL] (L = 1,8dimethyl-1,3,6,8,10,13-hexaazacyclotetradeca-2,6,9,13-tetraene) and [NiL] (L = 1,8-dibenzyl-1,3,6,8,10,13-hexaazacyclotetradeca-2,6,9,13-tetraene) containing two imidoylamidine (–N=CH-N(R)-CH=N-) linkages. Interestingly, [NiL](ClO4)2 consists of two stable conformational isomers and forms a 2D supramolecular structure. Synthesis and chemical properties of [NiL] and [NiL] are reported. Imidoylamidines are widely used as precursors for the synthesis of various organic compounds and polymers, exhibiting useful properties. Recently, some nickel(II) complexes of imidoylamidines (HN=CR-NH-CR=NH; R = alkyl group) have been also prepared and characterized. However, [NiL] and [NiL] are rare examples of 14membered hexaaza macrocyclic complexes that contain two imidoylamidine linkages.

Synthesis and Characterization of Lanthanide(III) Nitrate Complexes of an Hexaaza Macrocyclic Ligand

AbstractThe [2+2] barium(II) templated cyclocondensation of 2,6‐diacetylpyridine and ethylendiamine followed by an in situ reduction led to an isomeric mixture of the corresponding saturated macrocycles. The 6S,9S,15R,18R‐meso form of the hexaaza macrocyclic ligand (L) has been obtained by the partial crystallization method. The assignment of the proton and carbon NMR signals was based upon standard COSY, DEPT‐135 and HMQC measurements. The structure of the protonated ligand [H2L](NO3)2·3H2O could be confirmed by X‐ray diffraction. A serie of nitrate lanthanide complexes with L have been prepared. The metal complexes, with general formula [ML](NO3)3·xH2O (M = Nd, Eu, Gd, Tb and Tm), were easily prepared in good yield by direct reaction between the hydrated nitrate metal salt and the macrocyclic ligand. The crystal structure of [NdL(NO3)2](NO3)·H2O has been determined by X‐ray diffraction and shows a mononuclear structure with the neodymium atom in 10‐coordinate with a N6O4 environment. The coordination around the neodymium ion can be described as distorted bicapped cube.

A Selective Membrane Electrode for Lanthanum(III) Ion Based on a Hexaaza Macrocycle Derivative as Ionophore

We have developed a highly La(III)-selective PVC membrane electrode based on a hexaaza macrocycle, 8,16-dimethyl-6,14-diphenyl-2,3,4:10,11,12-dipyridine-1,3,5,9,11,13-hexaazacyclohexadeca-3,5,8,11,13,16-hexaene [Bzo2Me2Pyo2(16)-hexaeneN6] (I) as membrane carrier, dibutylbutyl phosphonate (DBBP) as solvent mediator and sodium tetraphenylborate (NaTPB) as lipophilic additive. The best performance was given by the membrane of macrocycle I having a composition 10:260:5:120 (I:DBBP:NaTPB:PVC). The electrode exhibits a Nernstian response to La(III) ion in the concentration range 1.0x10(-1)-7.94x10(-7) M with a slope of 19.8+/-0.2 mV/decade of concentration and a detection limit of 5.62x10(-7) M. The response time of the sensor is 12 s and it can be used over a period of 4 months with good reproducibility. The electrode works well over a pH range of 2.5-10.0 and in partially non-aqueous medium with up to 30% organic content. The sensor was also used as an indicator electrode in potentiometric titration of La(III) ions with EDTA and for determining La(III) concentration in real samples.

Synthesis, Characterization and Electrochemistry Behavior of Nickel[II] Cobalt[II], and Copper[II] Complexes of 14‐Membered Hexaaza Macrocycle

The synthesis of Nickel[II], Cobalt[II] and Copper[II] complexes is reported. The structure of the complexes has been characterized by IR, thermal analysis and X‐ray power diffraction analysis. Electrochemical behavior of the complexes is also investigated. It is proposed that the structure of the complexes is square‐planar which can be used to explore the interaction between the complexes and DNA.

Synthesis and Characterization of New Hexaaza Macrotricyclic Copper(II) Complexes with a 5-6-6-6 Chelate Ring Sequence

The design and synthesis of new polyaza macrocyclic complexes have received much attention, since their chemical properties are strongly influenced by the structural characteristics of the ligands. Metal-directed condensation reactions of coordinated amines with formaldehyde are useful for the preparation of polyaza macrocyclic complexes containing N-CH2-N linkages. 4-13 For instance, the squareplanar complexes [ML] and [ML] (M = Cu(II) or Ni(II)) with a 5-6-5-6 chelate ring sequence have been prepared by the one-pot reaction of Eq. (1) or (2). Although numbers of polyaza macrocyclic complexes containing N-CH2-N linkages have been prepared and investigated, most of them contain 14-membered hexaaza macrocycles and have squareplanar coordination polyhedron with a 5-6-5-6 chelate ring sequence. Some 15-membered hexaaza macrocyclic complexes with a 5-6-5-5-4 chelate ring sequence, such as [NiL] (Eq. (3)), have been also investigated. As far as we know, however, the preparation of 15-membered hexaaza macrocyclic copper(II) or nickel(II) complexes with a 5-6-66 chelate ring sequence is not reported to date. Herein, we report new copper(II) complexes [CuL] and [CuL] with a 5-6-6-6 chelate ring sequence. They were prepared by the metal-directed reactions (Eqs. (4) and (5)) of appropriate amines with formaldehyde. Interestingly, [CuL] is considerably inert against decomposition even in concentrated acid solution, unlike [CuL] and other polyaza macrocyclic copper(II) complexes with a 5-6-6-6 chelate ring sequence. Synthesis and chemical properties of the copper(II) complexes are described.

Enantiopure Chiral Macrocyclic Lanthanide Complexes Derived from (R)-2,2′-Diamino-1,1′-binaphthyl and 2,6-Diformylpyridine

The template condensation of (R)-2,2′-diamino-1,1′-binaphthyl and 2,6-diformylpyridine leads to lanthanide(III) complexes of the new chiral hexaaza macrocycle L that adopts highly twisted conformation in [LnL](NO3)3 complexes. The complexes have been characterised by ESI MS spectrometry and NMR spectroscopy. The analogous N2O4 chiral crown ether L2 that has the same carbon skeleton as L does not exhibit tendency to bind lanthanide(III) ions. The X-ray crystal structure of L2 exhibit squeezed conformation of the macrocycle and spatial disposition of donor atoms that does not predispose it for coordination of lanthanide(III) ions.