Rufina Bastida

Synthesis and characterisation of four novel NxOy-Schiff-base macrocyclic ligands and their metal complexes

Macrocyclic Schiff-bases, L1 and L2, and bis-macrocyclic ligands, L3 and L4, have been prepared by [1 + 1] and [2 + 1] cyclocondensation of 1,7-bis(2′-formylphenyl)-1,4,7-trioxaheptane or 2,6-bis(2-formylphenoxymethyl)pyridine with 2,6-bis(o-aminophenoxymethyl)pyridine or 1,2,4,5-tetraaminebenzene · 4HCl, respectively. The related YIII, MII (M=Co, Ni, Zn, Cd or Pb) and LnIII nitrate or perchlorate complexes have been synthesised following a template procedure, demonstrating the effectiveness of these metal ions to promote the assembly of these four symmetric Schiff-base macrocycles. The complexes were characterised by elemental analyses, molar conductivity, mass spectrometry, i.r., u.v.–vis, and 1H-n.m.r spectroscopy.

Synthesis and helical polymeric structure of a luminescent pendant-armed macrocyclic silver(I) complex with Ag–Ag interactions

An interesting 1D helical chain complex has been obtained with silver(I) nitrate and a tetrapyridyl pendant-armed macrocyclic ligand (L) in acetonitrile. The X-ray crystal structure of the complex, which has the formula ([Ag3L(NO3)](NO3)2·8H2O)∞, presents silver–silver interactions in an infinite spiral chain structure that is unprecedented in such pyridyl macrocyclic complexes. The structure forms a large cavity or channel that contains the silver(I) ions and presents face-to-face π,π-stacking between the pyridyl rings. The complex shows fluorescence in the solid state and acetonitrile solution at room temperature.

Synthesis and Characterization of Some Metal Complexes with New Nitrogen–Oxygen Donor Macrocyclic Ligands – X‐ray Crystal Structures of a 26‐Membered Reduced Monoprotonated Macrocycle and a 20‐Membered Pendant‐Arm Schiff‐Base Macrocyclic Cadmium(II) Complex

New series of macrocyclic Schiff-base lanthanide(III), yttrium(III), and cadmium(II) complexes, [M(1)]Xn (X = NO, M = Y, Ln = La–Yb except Pm and Dy; X = ClO, M = Cd, La, Ce, Pr, Sm, Gd, or Er) and [M(3)]Xn (X = NO, M = Dy; X = ClO, M = Er and Cd), have been prepared by cyclocondensation of O1,O7-bis(2-formylphenyl)-1,4,7-trioxaheptane with O1,O7-bis(2-aninyl)-1,4,7-trioxaheptane (1) or tris(2-aminoethyl)amine (3) in the presence of the appropriate metal salt as a template agent. The Schiff-base macrocycles 1 and 3 are also formed in the absence of a metal ion. Treatment of 1 with NaBH4 in methanol gives the diamine macrocycle 2. The reactions of LnIII, CdII, and YIII ions with 2 have also been investigated. The crystal structures of the monoprotonated ligand 2 and of the complex [Cd(3)](ClO4)2 have been determined by X-ray diffraction analysis.

Synthesis and characterisation of silver, zinc and cadmium compounds with an N3O2 Schiff base macrocycle: the crystal and molecular structures of the silver(I) and cadmium(II) complexes

Abstract The metal-templated cyclocondensation of 2,6-diformylpyridine and 1,4-bis(2-aminophenoxy)butane in the presence of silver(I), zinc(II) and cadmium(II) salts gave the following di-imine macrocyclic complexes: [AgL](ClO4) (1), [ZnL](ClO4)2·2H2O (2), [ZnL](NO3)2 (3), [CdL(H2O)2](ClO4)2 (4) and [CdL(NO3)(CH3OH)](NO3) (5) (L=macrocyclic ligand). All compounds have been characterised by microanalysis, IR, conductivity measurements, MS-FAB and 1H NMR spectroscopic studies. Compounds 1, 4 and 5 were also studied by single-crystal X-ray diffraction.

Complexes of lead(II) and lanthanide(III) ions with two novel 26-membered-imine and -amine macrocycles derived from 2,6-bis(2-formylphenoxymethyl)pyridine☆

Abstract acrocyclic Schiff-base lanthanide(III) complexes, [LnL1] [X]3 (X = NO3, Ln = La, Ce, Pr, Ce, Pr, Nd, Sm, Eu, Gd Tb, Ho, Er, Tm, Yb or Lu: X = ClO4, Ln = La, Ce, Pr, Nd, Sm, Eu, Tb, Dy or Er) and the complex [PbL1] [ClO4]2 have been prepared by cyclocondensation of 2,6-bis(2-formylphenoxymethyl)pyridine and 1,5-bis(2-aminophenoxyl)-3-oxapentane in the presence of the appropriate metal salt as a template agent. The Schiff-base macrocycle L1 is also formed in the absence of the metal ion. Treatment of L1 with NaBH4 in methanol gave the di-amine macrocycle L2. The reactions of lanthanide(III) ions with L2 were also investigated.

Synthesis of a new tetra-cyanomethylated macrocyclic ligand with a nanotubular structure. X-Ray crystal structures of mono-, di-nuclear and polymeric metal complexes

A new pendant-armed macrocyclic ligand, L1, bearing four cyanomethyl pendant groups has been synthesized by N-alkylation of the tetraazamacrocyclic precursor L with bromoacetonitrile. The X-ray structural analysis of the ligand L1 shows the formation of tubular arrays, and reveals intra- and inter-molecular π-stacking interactions between the pyridyl groups of the macrocyclic backbone. Metal complexes of L1 have been synthesized and characterized by microanalysis, MS-FAB, conductivity measurements, IR, UV-Vis, 1H and 13C NMR spectroscopy and magnetic studies. Crystal structures of the ligand L1 as well as of the complexes [ZnL1](NO3)2·2H2O, [Ag2L1(NO3)2] and [Ag2L1](ClO4)2·4CH3CN have been determined by single crystal X-ray crystallography. Different macrocyclic disposition has been found in relation to the metal ion employed and even when different salts of the same metal are used. The X-ray studies show the presence of two metal atoms within the macrocyclic ligand in [Ag2L1(NO3)2] and [Ag2L1](ClO4)2·4CH3CN showing a monomeric and a polymeric nature respectively. The crystal structure of [ZnL1(NO3)2]·2H2O shows a mononuclear endomacrocyclic complex with the metal ion coordinated to the six nitrogen atoms in a distorted octahedral environment.

Cadmium(II) and Lead(II) Complexes with Novel Macrocyclic Receptors Derived from 1,10-Diaza-15-crown-5

Two novel macrocycles, N,N′-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 (L1) and a non-symmetric cryptand incorporating a pyridinyl Schiff-base spacer (L3), both derived from 1,10-diaza-15-crown-5, have been shown to act as receptors for lead(II) and cadmium(II) guests. The X-ray crystal structures reveal an anti conformation for the free ligand L1, but a syn arrangement in the lead(II) complex, [PbL1](ClO4)2. The corresponding cryptates of L3 can be prepared by simple transmetallation reactions starting from the barium cryptate, showing the preference of L3 for the heavy metal ions. The lead(II) ion, unlike cadmium(II), has been shown to be capable of acting as a template agent in the synthesis of L3. The X-ray crystal structures of the metal cryptates allow an insight into the influence of the nature of the metal ion guest on the conformation of the macrobicyclic receptor L3; the most significant changes are a different folding of the crown and variations in the distance between the two pivotal nitrogen atoms and the imine nitrogen atoms. The cryptand can thus expand or contract its cavity in order to accommodate the different metal ions.

Metal complexes with four macrocyclic ligands derived from 2,6-bis(2-formylphenoxymethyl)pyridine and 1,7-bis(2′-formylphenyl)-1,4,7-trioxaheptane

New series of [1� /1] Schiff-base macrocyclic complexes have been prepared by reaction between 1,5-bis(2-aminophenoxy)-3oxapentane and 2,6-bis(2-formylphenoxymethyl)pyridine (L 1 ) or 1,7-bis(2?-formylphenyl)-1,4,7-trioxaheptane (L 3 ), using the metal salts of Co(II), Ni(II), Ag(I), Zn(II) or Pb(II) as template agents. Treatment of both diiminic ligands with NaBH4 gives the corresponding reduced macrocycles L 2 and L 4 ; the complexation capacity of both reduced ligands towards Co(II), Ni(II), Ag(I), Zn(II) and Pb(II) ions has been also investigated. The complexes have been characterised by elemental analyses, molar conductivity, mass spectrometry, IR, UV � /Vis and 1 H NMR spectroscopy, diffuse reflectance and magnetic measurements.

Coordination chemistry of copper(II) with oxaaza macrocyclic ligands: crystal structure of a dinuclear tetramer copper(II) complex

AbstractA new series of copper(II) nitrate and perchlorate complexes with eight different oxaaza macrocyclic ligands (L 1 / L 8 )have beenprepared and characterised. Complexes with the diiminic ligands L 1 / L 6 have been obtained by template condensation of theappropriate dialdehyde and diamine precursors; the reduced L 7 and L 8 macrocycles have been synthesised using a direct route. Theoverall geometry and bonding mode have been deduced on the basis of elemental analysis data, IR, FAB, UV / Vis spectroscopy,cyclic voltammetry, and conductivity and magnetic susceptibility measurements. After treatment of an acetonitrile solution of thecomplex [L 6 Cu](ClO 4 ) 2 / 5H 2 O with acetic acid 15%, dark blue single crystals, the result of a secondary reaction, were isolated andcharacterised as a new binuclear tetramer copper(II) complex, with formula C 13 H 28 ClCu 2 N 3 O 10 .# 2003 Elsevier Science Ltd. All rights reserved. Keywords: Copper complexes; Template synthesis; Direct synthesis; Schiff-base; Oxaaza macrocycles

Complexes of lead(II) and lanthanide(III) ions with a macrocyclic ligand containing a furan head unit. Crystal structure of a methanol inclusion compound of a novel macrocycle

Abstract A Schiff-base polyoxaazamacrocycle derived from 2, 5-diformylfuran and 1, 5-bis(2-aminophenoxy)-3-oxapentane was obtained by a template procedure as mononuclear lanthanide(III) and lead(II) complexes. In the absence of the metal salt the macrocycle was not formed. The complexes were characterized by elemental analysis, molar conductivity, mass spectrometry and IR, 1 H NMR and 13 C NMR spectroscopy. The reduction of the Pb II complex with sodium borohydride yielded a novel polyoxaazamacrocycle containing a furan head and aromatic lateral units; the X-ray crystal structure of its methanol inclusion compound is reported.