Macrocyclic Schiff Base Complexes Research Articles

Synthesis and Characterization of a Series of Functional Pendant-Arm Schiff Base Macrocyclic Complexes

A series of new functional pendant-arm Schiff base macrocyclic complexes have been synthesized by template cyclocondensation between sodium 4-substituted phenolate and N,N-bis(2-aminoethyl)-8-methylquinolineamine and subsequent in situ transmetallation by metal perchlorates. The reaction products of the corresponding Mn2+ Cd2+, Ni2+ and Zn2+ complexes have been characterized by elemental analyses, infrared and ES-MS spectra. The magnetic moments of the dinuclear Mn(II) and Ni(II) complexes at room temperature suggest some antiferromagnetic interactions in these compounds. It is proposed that the metal ions in these complexes are located in distorted-octahedral (six-coordinated) or square-pyramidal (five-coordinated) geometries and the two pendant arms approach the metal ion at the opposite side of the macrocycle.

Rare earth macrocyclic complexes derived from spermine

The yttrium and lanthanide perchlorates were found to act as templates for the cyclic [1+1] condensation of 2,6-diacetylpyridine with spermine (4,9-diazadodecane-1,12-diamine) to yield 19-membered pentadentate Schiff base macrocyclic complexes with an N 5 set of donor atoms. The complexes were characterized by spectral data (IR, 1H NMR, FAB-MS), thermogravimetric and elemental analysis.

Formation of dinuclear macrocyclic and mononuclear acyclic complexes of a new trinucleating hexaaza triphenolic Schiff base macrocycle: structure and NLO properties

Reaction of a new chiral and optically active trinucleating 3 + 3 condensed hexaaza triphenolic Schiff base macrocycle H3L1I with transition metal ions (Zn, Cu, Ni, Co, Fe and Mn) in 1∶3 molar ratio in methanol under reflux conditions resulted in complexes. Analytical data reveal the formation of 2 + 2 condensed dinuclear macrocyclic Schiff base complexes, instead of the expected trinuclear macrocyclic complexes. X-Ray crystallographic studies on three of these complexes established their dinuclearity. On the other hand, reaction of I with metal ions (Zn, Cu, Fe and Mn) in 1∶3 molar ratio in methanol at room temperature for 2 h resulted in one-side condensed mononuclear acyclic complexes. This is confirmed by the crystal structure of the manganese complex. Second-order non-linear properties are discussed.

Synthesis and Spectral Studies of Some Tin(II) and Tin(IV) Macrocyclic Schiff Base Complexes

The present paper is a report on the synthesis and characterisation of some tin(II) and tin(IV) macrocyclic Schiff base complexes. These complexes have been prepared by the reaction of tin dichloride, tin tetrachloride and dimethyltin dichloride with 1,3-diaminopropane and benzil or m-phenylenediamine and acetylacetone in oxygen-free nitrogen atmosphere using THF as the reaction medium. On the basis of elemental analyses, conductance measurements, molecular weight determinations, and 119Sn Mössbauer, electronic, infrared, 1H NMR and 119Sn NMK spectral studies, structures have been proposed for these new complexes.

Zinc and cadmium complexes of an 18-membered N4O2 oxaaza-Schiff base macrocycle and the corresponding reduced form †

The metal templated (Cd and Zn) cyclocondensation of 2,6-pyridinedicarbaldehyde and 1,5-bis(2-aminophenoxy)-3-azapentane is reported together with the crystal structures of two mononuclear cadmium macrocyclic Schiff base complexes, [CdL1(NO3)2] 1 and [CdL1(H2O)2][ClO4]2 2 and a dinuclear, µ-hydroxy-bridged zinc macrocyclic Schiff base complex [Zn2L12(OH)][ClO4]3·CH3CN 3·CH3CN. The corresponding reduced macrocycle, L2, has been synthesised by using the MnII-templated cyclocondensation of 2,6-pyridinedicarbaldehyde and 1,5-bis(2-aminophenoxy)-3-azapentane in methanol followed by an in situ reductive demetallation of the Schiff base macrocyclic manganese(II) complex using excess sodium borohydride. The crystal structures of the free macrocycle L2, [CdL2(NO3)2] 4 and [CdL2(CH3CN)2][ClO4]2 5 are reported.

Dinuclear silver(I) complexes of bibracchial tetraimine Schiff base macrocycles derived from pyrrole-2,5-dicarbaldehyde

The cyclocondensation of pyrrole-2,5-dicarbaldehyde and the amines N,N-bis(2-aminoethyl)- and N,N-bis(3-aminopropyl)-2-(aminomethyl)pyridine in the presence of silver(I) nitrate yielded homodinuclear bibracchial tetraimine Schiff base macrocyclic complexes [Ag2(L3)] 1 and [Ag2(H2L4)(ClO4)2]·CH3CN 2. In 1 the Ag· · ·Ag separation is 2.748 A. In 2 the silver atoms Ag(1) and Ag(2) are disordered over two sites with refined occupancies of 94.12 and 97.22% respectively. They are three-co-ordinate in the molecule having higher silver site occupancy and four-co-ordinate in that molecule having lower occupancy; the Ag· · ·Ag separations are 5.881 and 7.224 A respectively. There are protonated imine nitrogen atoms present in both molecules and the structure contains a disordered acetonitrile of crystallisation.

A heterodinuclear macrocyclic complex containing both nickel(II) and palladium(II) ions

The first heterodinuclear macrocyclic Schiff base complex containing both first- and second row transition metal ions, [NiPdL](ClO4)2·3MeCN has been synthesised and characterised by spectroscopic methods; the X-ray structure of this complex and its mononuclear precursor are reported.

Binuclear nickel(II) and copper(II) complexes of amide-containing two-armed and macrocyclic ligands

Two new acyclic, potentially binucleating amide-containing ligands.H3L1 andH3L2, have been synthesised from the reaction of 4-methylphenol-2,6-diacyl chloride with an excess of 1,2-diaminobenzene or of 1,2-diamino-4,5-dimethylbenzene, respectively. Dicopper(II) complexes, [Cu2(L1)(X)] where X = CH3COO− or OH−, ahve been made fromH3L1 but the analogous nickel complexes could not be prepared and no complexes with either copper or nickel could be prepared fromH3L2. Interestingly, Schiff-base macrocyclic complexes derived from reactions ofH3L1 andH3L2 with 2,6-diformyl-4-methylphenol, 4-t-butyl-2,6-diformylphenol, or S-(2,6-diformyl-4-methyl-phenyl)-dimethylthiocarbamate, were successfully templated using these same two metal ions and resulted in the isolation of nine dimetallic complexes. A variety of structural modifications were made to the macrocycles via the choice dialdehyde precursor, including changing a phenolate bridge for a thiophenolate one, in an attempt to increase the solubility of the products.

First of a new family of tetraamine bis(μ-thiolate)-containing macrocycles: structure and stepwise oxidations and reductions of the dinickel(ii) complex

Reduction of a dinickel(II) dithiolate Schiff-base macrocyclic complex with sodium borohydride results in a ‘bowl’-shaped dinickel(II) dithiolate amine macrocyclic complex which exhibits four separate one-electron redox processes.

First observation of non-bridging thiolates or tetrahedral geometries within thiolate-containing Schiff-base macrocycles: [Zn2L][CF3SO3

The structure determination of [Zn2L][CF3SO3]2 1 reveals the first example of non-bridging thiolates within a thiolate-containing Schiff-base macrocyclic complex: the flexibility of such macrocycles is also clearly demonstrated as this is the first example of the provision of distorted tetrahedral metal ion binding sites.

Dinuclear silver(I) complexes of 24-membered bibracchial tetraimine Schiff base macrocycles derived from 2,5-diformylthiophene

The cyclocondensation of 2,5-diformylthiophene and the amines N, N-bis-(2-aminoethyl)-2-phenylethylamine, N, N-bis-(2aminoethyl)-t-butyl-amine and N, N-bis-(2-aminoethyl)-t-butyl-amine in the presence of silver(I) salts yields homodinuclear bibracchial tetraimine Schiff base macrocyclic complexes. The structures of two such complexes are also reported. The complex Ag 2L 4(NO 3)(PF 6) (2) crystallises in the triclinic space group P l (C i l , No. 2) and has unit-cell dimensions a = 12.834(6), b = 13.183(6), c = 14.588(7) A ̊ , α = 64.86(4), β = 79.77(4), γ = 69.44(3)° with Z = 2; there is a monodentate and singly bridging nitrate anion present and the AgAg separation is 4.161 Å. The complex Ag 2L 4(CH 3CN) 2(BF 4) 2·CH 3CN (9) crystallises in the triclinic space group P l (C i l , No. 2) and has unit-cell dimensions a = 9.297(4), b = 12.985(3), c = 21.770(5) A ̊ , α = 91.570(10), β = 92.33(3), γ = 97.92(3) ° with Z = 2 ; there is a strongly bonded acetonitrile molecule coordinated to each silver atom and the AgAg separation is 4.920 Å.

The template synthesis and X-ray characterization of pyrrole-derived hexadentate uranyl(VI) Schiff-base macrocyclic complexes

The template condensation of 3,4-diethyl-2,5-dicarbaldehyde with ethylenediamine and 1,3-propanediamine in the presence of UO 2(NO 3) 2 gave neutral complexes of formulae UO 2(C 24H 32N 6) ([UO 2(bi-pyen)], 2) and UO 2(C 26H 36N 6) ([UO 2(bi-pytmd)], 3), respectively. X-Ray diffraction quality single crystals were obtained from chloroform/methanol. In the case of 2, these were monoclinic, space group C2/ c, with a = 30.549(5), b = 8.251(1), c= 21.969(4) A ̊ , β = 114.47(1)°, V = 5040(1) A ̊ 3, Z = 8, ϱ calc , = 1.78 g cm −3 . Crystals of 3 were also monoclinic, space group C2/ c, with a = 26.946(7), b = 9.436(2), c = 10.862(2) A ̊ , β = 105.04(2)°, V = 2667(1) A ̊ 3, Z = 4, ϱ calc = 1.75 g cm −3 . In the X-ray structure of 3, the complex lies on a crystallographic twofold axis. For 2, the final R = 0.0335, wR = 0.0371 for 297 parameters and 4475 reflections [ F ⩾ 4( σ( F oo ))], while for 3, the final R = 0.0223, wR = 0.0265 for 213 parameters and 2810 reflections [ F ⩾4 ( σ( F o ))]. In each complex, the uranyl(VI) cation is bound to all six nitrogen atoms such that the metal center, with its two apical oxygen atoms, lies in a distorted hexagonal bipyramidal environment. The change in overall macrocycle size that results in going from 2 to 3 does not affect the UN bond lengths. Rather, the principal difference between 2 and 3 is the exten tent of the twist between the two nearly planar halves of the macrocycle. In 2, the imine-pyrrole-imine dihedral angle is 17.5(1)° while in 3 it is 35.7(1)°. On the other hand, it is near 0° in an earlier reported complex, 1, derived from o-phenylenediamine [J.L. Sessler, T.D. Mody and V. Lynch, Inorg. Chem., 31 (1992) 531]. Complex 1 displays two reversible oxidations at +0.82 V and +1.09 V versus F c F c + in CH 2Cl 2 containing TBAPF 6, while complexes 2 and 3 display irreversible oxidation waves at +1.22 V, +1.46 V and +1.22 V and +1.47 V versus F c F c + , respectively. Complexes 1, 2, and 3 also display quasi-reversible uranyl-centered reductions at −0.85 V, −1.02 V, and −0.96 V versus F c F c + , respectively.

Synthesis and Characterization of Lanthanide Schiff Base Macrocyclic Complexes

Abstract A new macrocyclic Schiff base 1, 2, 4, 8, 10, ll-hexaza-3, 9-bis-4-pyrido-tetradeca-3, 9, 12, 14-tetraene (HPT) on reaction with lanthanide chlorides yields complexes of general formula [MCl3(C20H24N8)][M = Ce(III), Pr(III), Dy(III), Sm(III), Gd(III) and Nd(III)]. These complexes were characterized by elemental analysis, i. r., UV-visible spectral studies, conductance and magnetic moment measurements. The magnetic moments and electronic spectra suggest that the lanthanide ions are 7-co -ordinate.

Preparation and structural characterization of dicopper(II) and dinickel(II) imidazolate-bridged macrocyclic Schiff base complexes

Preparation and structural characterization of dicopper(II) and dinickel(II) imidazolate-bridged macrocyclic Schiff base complexes

New hexaaza macrocyclic binucleating ligands. Oxygen insertion with a dicopper(I) Schiff base macrocyclic complex [Erratum to document cited in CA113(24):223409t

New hexaaza macrocyclic binucleating ligands. Oxygen insertion with a dicopper(I) Schiff base macrocyclic complex [Erratum to document cited in CA113(24):223409t

New hexaaza macrocyclic binucleating ligands. Oxygen insertion with a dicopper(I) Schiff base macrocyclic complex

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew hexaaza macrocyclic binucleating ligands. Oxygen insertion with a dicopper(I) Schiff base macrocyclic complexRached Menif, Arthur E. Martell, Philip J. Squattrito, and Abraham ClearfieldCite this: Inorg. Chem. 1990, 29, 23, 4723–4729Publication Date (Print):November 1, 1990Publication History Published online1 May 2002Published inissue 1 November 1990https://doi.org/10.1021/ic00348a028RIGHTS & PERMISSIONSArticle Views928Altmetric-Citations176LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (807 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Perchlorate ion-selective coated-wire electrode based on a macrocyclic Schiff's base complex

Perchlorate ion-selective coated-wire electrodes based on the metal complexes of a macrocyclic Schiff's base as the electroactive material are described. The macrocyclic Schiff's bases of barium, copper and lead complexes were derived by condensation of 1,3-diamino-2-hydroxypropane with 2,6-diacetylpyridine and their stability constants were determined by conductometry. Perchlorate ion-selective coated-wire electrodes based on these complexes with various plasticisers used as membrane solvents were examined and the electrode using BaL 1(ClO4)2 and dibutyl phthalate was found to have the optimum Nernstian properties and selectivity. The Nernstian response potential slope of this electrode was 58 mV per decade for an activity change in solutions of NaClO4 in the concentration range 1.0 × 10–1–4.0 × 10–6 mol dm–3.

Solution and solid state characterization of europium and gadolinium Schiff base complexes and assessment of their potential as contrast agents in magnetic resonance imaging

Two lanthanide Schiff base macrocyclic complexes, LnAM(OAc){sub 2}Cl{center dot}4H{sub 2}O (Ln = Eu, Gd; HAM - HexaAzaMacrocycle = C{sub 22}H{sub 26}N{sub 6}), have been characterized in view of the potential of the Gd complex as a magnetic resonance imaging (MRI) contrast agent. The relaxivity of GdHAM(OAc){sub 2}Cl was measured at 300 and 20 MHz and is as high as that for the gadolinium aquo ion. The number of coordinated waters, q, was measured by comparison of the luminescent lifetimes of EuHAM(OAc){sub 2}Cl in H{sub 2}O and D{sub 2}O and found to be between three and four. The complex GdHAM(OAc){sub 2}Cl{center dot}4H{sub 2}O was characterized by single-crystal X-ray diffraction. The complex crystallizes in space group P{bar 1} with Z = 2, a = 10.032 (2) {angstrom}, b = 12.765 (2) {angstrom}, c = 13.668 (3) {angstrom}, {alpha} = 69.190{degree} (9){degree}, {beta} = 72.405{degree} (9){degree}, and {gamma} = 74.07{degree} (1){degree}.

Complexes of ligands providing endogenous bridges. Part 5. Solution studies on a novel ‘3 + 3’ hexamine Schiff-base macrocyclic complex of lanthanum

Structural studies in solution show that when lanthanum nitrate is used as a template in the reaction of 2,6-diacetylpyridine and 1,3-diamino-2-hydroxypropane a ‘3 + 3’ macrocycle containing three lanthanum ions is the predominant species formed. Hydrogen-1 n.m.r. decoupling and n.O.e. difference spectroscopy confirms the presence of a two-fold axis of symmetry where two ‘sides’ of the macrocycle are identical and different from the third.

A novel (3 + 3) hexaimine Schiff base macrocyclic complex of lanthanum

A novel (3 + 3) hexaimine Schiff base macrocyclic complex of lanthanum