Matilde Fondo

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Verified

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• Dr.
• Professor (Associate) at University of Santiago de Compostela

Dy (LMe)(H2O)]CF3SO3·0.25H2O (1·0.25H2O), where H2LMe is the reported ligand 2,2′‐(((pyridine‐2,6‐diylbis (methylene))bis((pyridin‐2‐ylmethyl)azanediyl))bis (methylene))bis(4‐methylphenol), shows the DyIII ion in an N5O3 environment, with triangular dodecahedral geometry (D2d symmetry). 1·0.25H2O is a single ion magnet (SIM) with an energy barrier...

Hexaazamacrocyclic Schiff bases have been extensively combined with lanthanoid (Ln) ions to obtain complexes with a highly axial geometry. However, the use of flexible hexaazatetraamine macrocycles containing two pyridines and acyclic spacers is rather uncommon. Accordingly, we obtained [DyL(OAc)2]OAc·7H2O·EtOH and [DyLMe2(Cl)2]Cl·2H2O, where L and...

Novel complexes {[Dy(LN6en)(OAc)2](NO3)}·2H2O (1·2H2O) and {[Dy(LN6prop)(OAc)2](NO3)}·CHCl3 (2·CHCl3), containing partially flexible symmetric N6 macrocycles, are reported. We explore the influence of the spacer length between two symmetrical N3 rigid moieties of...

The reactivity of the new flexible potentially pentadentate N3O2 aminophenol ligand H4Lr (2,2′-((pyridine-2,6-diylbis(methylene))bis(azanediyl))diphenol) towards different dysprosium salts and holmium(III) nitrate was investigated. Accordingly, this reactivity seems to greatly depend on the metal ion and salt employed. In this way, the reaction of...

In this paper, the lanthanoid complexes of N5 and N6 macrocycle ligands, without pendant arms or additional heteroatoms, are surveyed. This review covers the period from 2015 to the current date, since in 2014 Schiff base macrocyclic ligands incorporating the pyridine moiety, and their complexes, were revised, and in 2015 the chemistry of pentaaza...

The influence of the solvent in the reaction of dysprosium(III) chloride hydrate with the N3O2 ligand H2L (2,6-bis(2-hydroxyphenyliminomethyl)pyridine) was studied To this end, the new mononuclear chloride complex [Dy(L)Cl(H2O)2] (1) was isolated in absolute ethanol as solvent, without any evidence of the hydrolysis of the ligand. This clearly cont...

The formation of imidazolidines from secondary amines and aldehydes is well known. This small cycle can act as a nitrogen donor, and it is usually stable when it coordinates to metal ions. Sometimes, imidazolidines acting as ligands undergo breaking of the C-N bond when coordinating to the metal center, yielding related amines. However, the reorgan...

The Schiff base ligand H2SB derived from the condensation of N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide with 4-formyl-3-hydroxybenzoic acid has been investigated as a chemosensor for the detection of CdSe-Cys QDs in water samples. We immobilized H2SB onto cellulose paper by forming an amide bond, which results from the condensatio...

We studied the interaction of Cu²⁺ ions and CuO nanoparticles with the fluorescent Schiff base ligand H3L, which derives from the condensation of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide (DsA). A detailed assignment of the most significant bands of the electronic and infrared spectra of H3L an...

The tetranuclear linear complex [Dy4(1,1,4-H3Lr)2(OAc)6]·CH3OH (1·CH3OH) was satisfactorily prepared and characterized. Its X-ray structure shows that it contains two types of octacoordinated DyIII ions, with distorted triangular dodecahedral and square antiprism geometries. This complex is an SMM, with multiple relaxation pathways, and with an ani...

We investigated the easily synthesized ligand H3L as a fluorescent chemosensor for the detection of CdSe nanoparticles (CdSe NPs) and L-cysteine-capped CdSe quantum dots (CdSe-Cys QDs) in ethanol–water samples. A drastic quenching of the fluorescence emission of H3L at 510 nm occurred, as a result of the addition of CdSe NPs and CdSe-Cys QDs. A sol...

Since the discovery of Quantum Dots (QDs) by Alexey I. Ekimov in 1981, the interest of researchers in that particular type of nanomaterials (NMs) with unique optical and electrical properties has been increasing year by year. Thus, since 2009, the number of scientific articles published on this topic has not been less than a thousand a year. The in...

A new synthetic method allows isolating fluoride-bridged complexes Bu4N{[M(3NO2,5Br-H3L1,1,4)]2(μ-F)} (M = Dy, 1; M = Ho, 2; M = Gd, 3) and Bu4N{[Dy(3Br,5Cl-H3L1,2,4)]2(μ-F)}·2H2O, 4·2H2O. The crystal structures of 1·5CH3C6H5,·2·2H2O·0.75THF, 3, and 4·2H2O·2THF show that all of them are dinuclear compounds with linear single fluoride bridges and oc...

This work describes an uncommon new case of imine hydrolysis, leading to the formation of a carboxylate group. The conditions of the media that favor this conversion, which seem to be mediated by the presence of DyIII, are analyzed. The process brings about the formation of a dysprosium complex of formula {[(DyL2)2Na2(H2O)8][Et3NH]2[DyL2]2}·14H2O (...

With the aim of investigating the development of an easily synthesized dansyl-based fluorescent probe for detecting heavy-metal-based nanomaterials in aqueous solution, we synthetized and characterized a Schiff-base ligand, which we named H3L. It was derived from the reaction of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino...

The mononuclear complexes [Dy(3Br,5Cl-H3L1,1,4)(D)]·solvate (D = H2O, solvate = 0.25MeOH, 1W·0.25MeOH; D = Py without solvate, 1Py), and [Dy(3NO2,5Br-H3L1,1,4)(H2O)] (2W) were isolated. The crystal structures of 1W·0.25MeOH, 1Py and 2W·2CH3C6H5 show that the DyIII ion is octacoordinated, in N4O4 or N5O3 environments, with distorted geometries, betw...

complexes were isolated from an heptadentate aminophenol ligand. The crystal structures of Dy 2 •2THF, and the pyridine adducts Dy 2 •2Py and Ho 2 •2Py, show that the complexes are dinuclear, with unsupported double phenoxide bridges, and that the N 4 O 4 environment of the Ln III centres is distorted triangular dodecahedral. The magnetic analysis...

The search for mononuclear lanthanoid-based single-ion magnets (SIMs) has increased the interest in some coordination environments with low coordination numbers, in combination with an axial symmetry, as they could maximize the anisotropy of complexes of oblate lanthanoid ions, such as dysprosium(III). In this sense, the pentagonal–bipyramid geomet...

This work describes the synthesis, characterization and reactivity towards HoIII of a potential heptadentate N4O3 aminophenol donor. The crystal structure of the [Ho(1,1,4-H3L)(1,1,4-H6L)] complex (1,1,4-H6L = 6,6′-(2-(5-bromo-2-hydroxy-3-nitrobenzyl)-2,5,8,11-tetraazadodecane-1,12-diyl)bis(4-bromo-2-nitrophenol)) shows that the holmium atom binds...

The mononuclear complex [Yb(H3L1,1,4)]•2MeOH (1•2MeOH), with a new heptadentate N4O3 ligand, was isolated and structurally characterised. The opto magnetic properties of 1•2MeOH were investigated, showing that this complex is a bifunctional compound. Accordingly, 1•2MeOH reveals two coexisting functionalities: field-induced single molecule magnet b...

The reactivity of the well-known pentadentate N3O2 Schiff base H2L (2,6 bis(2 hydroxyphenyliminomethyl)pyridine) towards a lanthanoid metal, in this case DyIII, has been investigated for the first time. This reactivity...

The present study deals with the investigation of Cu2+, Ni2+ and Pd2+ chelating potential of the Schiff base, (E)-N-(2-((2-hydroxybenzylidene)amino)benzyl)-4-methylbenzenesulfonamide (H2SB). Crystal structures of Ni(HSB)2, Pd(HSB)2 and Cu(HSB)2 have been elucidated from single crystal X-ray diffraction data. NMR spectroscopy showed the presence of...

We have explored the suitability of an O,N,N–donor Schiff base (H2SB) for obtaining dinuclear complexes with heavy metal ions such as Cu2+, Zn2+, Ni2+, and Co2+ (borderline acids) as well as Pd2+ and Cd2+ (soft acids). Spectroscopic studies demonstrated that the complexation of H2SB and Cu2+, Zn2+, Ni2+, Co2+, Pd2+, and Cd2+ occurred at a 1:1 stoic...

Here we report the synthesis and characterization of a mononuclear gadolinium complex (Gd) and two heteronuclear Zn-Gd complexes (ZnGd and Zn2Gd), which contain two similar three-armed ligands that display an external compartment suitable for lanthanoid ions, and two internal compartments adequate for zinc (II) ions [H3L′ = (2-(3-formyl-2-hydroxy-5...

The reduction of functionalized imines to yield amines is often an intricate task, since most of the methods described in the literature to reduce imines to amines do not take into account that many reducing agents have also basic character. In this way, iminic compounds that have phenol functions usually produce the phenolic salt of the precursor...

The coordination chemistry of dysprosium and terbium toward phosphine and arsine oxides was further explored. Thus, the new nitrate [M(NO3)3(Ph3PO)3] (M = Tb, 1; Dy, 2), [Dy(NO3)3(EtOH)(Ph3XO)2] (X = P, 3; As, 4), chloride [DyCl2(Ph3AsO)4]Cl (5), triflate [Dy(OTf)2(MePh2PO)4]OTf (6; OTf = triflate) and hexafluoroacetylacetonate [M(hfa)3(Ph3PO)2] (h...

Three dinuclear complexes, [Tb2(H2daps)2(CH3OH)5.5(H2O)0.5](Cl)2 (Tb2Cl), [Dy2(H2daps)2(Cl)(CH3OH)3(H2O)]Cl (Dy2Cl), and [Dy2(H2daps)2(H2O)6](CF3SO3)2 (Dy2CF3SO3), as well as the heterohexanuclear compound [Zn2Dy4(daps)2(Hdaps)(Cl)3(OH)2(CH3OH)(H2O)5] (Zn2Dy4) (H4daps: 2,6-bis(1-salicyloylhydrazonoethyl)pyridine), which crystallize with different l...

We report the crystal structure of [ZnII2HoIII(L)(ald)(HO)(H2O)3(MeCN)](NO3)2·EtOH [H3L = 2-(5-bromo-2-hydroxy-3-methoxyphenyl)-1,3-bis[4-(5-bromo-2-hydroxy-3-methoxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) and Hald = 5-bromo-2-hydroxy-3-methoxy-benzaldehyde]. Despite the presence of two bulky multidentate ligands, as well as several monodentate...

Mononuclear complexes of stoichiometry [Ln(H3L)(H2O)(NO3)](NO3)2 (Ln = Tb, 1; Dy, 2, Er, 3), which crystallise with different solvates, and the heterotrinuclear compound [Zn2Dy(L)(NO3)3(OH)] (4) can be obtained with the same H3L compartmental ligand. The single X-ray crystal structure of the mononuclear complexes shows a LnO9 core with a muffin-lik...

An easily synthesized fluorescent probe for copper in aqueous samples, with short response time and at neutral pH, has been investigated. Through the chelation of Cu2+ ions or by binding to CuO nanoparticles the fluorescence emission of the 2 (aminomethyl)aniline derivative H2L is quenched by over 50%. Spectroscopic determination of association con...

A new H3L Schiff base ligand with three defined compartments, namely, two internal NNO and one external O6, was designed to allocate metal ions of different size. This ligand allows isolating heterodinuclear [ZnLn(HL)(NO3)(OAc)(D)](NO3) (Ln = Tb, D = H2O, ZnTb; Ln = Dy, D = CH3OH, ZnDy; and Ln = Er, D = CH3OH, ZnEr) complexes, where one of the NNO...

On the basis of selected reagents and reaction conditions, a chiral dinuclear trapped valence CoII/CoIII complex was conveniently obtained {[Co2(L)(O2CCH2CO2)(H2O)]·EtOH·1.25H2O, being H3L = 2-(5-bromo-2-hydroxyphenyl)-1,3-bis[4-(5-bromo-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine)}. This complex behaves as a compact am-phiphile, whose hydr...

An imidazolidine-phenolate ligand HL yields quadruple-bridged (μ-NCNimidazolidine)2(μ-Ophenolate)2 ferromagnetic dinuclear nickel and cobalt complexes. Both kinds of bridges contribute to the ferromagnetic coupling, but the ferromagnetism of these samples is mainly ascribed to the double μ-Ophenolate links, on the basis of density functional theory...

A new ligand H3L, with internal compartments for allocating 3d metal ions and external donors to bind 4f ions, was synthesized and completely characterized. Reaction of H3L with zinc(II) and gadolin ium(III) salts allows isolating the heteronuclear complex {[ZnGd(HL)(NO3)(OAc)(CH3OH)](NO3)}∙6H2O (1·6H2O). The ability of 1·6H2O to act as a magnetic...

The degradation under ambient humidity and room temperature of Pd(OAc)2(NEt3), which is an efficient catalyst for the aerobic oxidation of alcohols, to diethylamine and acetaldehyde derivatives is disclosed. Evolved diethylamine reacted with Pd(OAc)2 to give Pd(OAc)2(HNEt2), which is in dynamic equilibrium with Pd(OAc)2(HNEt2)2. The evolved acetald...

Octanuclear [Ni2(L)(H2O)2]4·7CH3OH·12H2O (1·7CH3OH·12H2O) and tetranuclear [Cu2(HL)(CH3OH)1.5(H2O)1.5]2(ClO4)2·2CH3OH (2·2CH3OH) (H4L = 4-carboxysalpn or N,N′-bis(4-carboxysalicylidene)-1,3-propylenediamine) are obtained from similar reactions, the main difference coming from the slightly higher pH of the medium for the nickel reaction vessel. This...

We report here the straightforward synthesis of some dimeric transition metal complexes of three Schiff base ligands, which were obtained by condensation of 2-tosylaminomethylaniline with 2,3-dihydroxybenzaldehyde (H2L1), 2,4-dihydroxybenzaldehyde (H2L2) and 4-formyl-3-hydroxybenzoic acid (H2L3), respectively. Both ligands and complexes were charac...

Coordination of a triptycene-based ditopic Schiff base ligand (H2L) with Zn2+ leads to the formation of a novel trinuclear circular species. A combination of 1H NMR spectroscopy, infrared spectroscopy, mass spectrometry and elemental analysis allow the unambiguous characterization of H2L and Zn3L3•8H2O. DFT molecular modelling has been used to stud...

We report here the straightforward synthesis of some d-block metal dimers of a Schiff base ligand obtained by condensation of 2‑tosylaminomethylaniline with 4-formyl-3-hydroxybenzoic acid (H2L). The easy bideprotonation of both -OH and ‑HNSO2- groups, as well as a suitable N,N,O binding domain that can simultaneously bind two metal ions through µ2-...

The potential ability of HL 1 [2-(1,3-dimethylimidazolidin-2-yl)phenol] and H 3 L 2 [2,2 0-(2-(2-hydrox-yphenyl)imidazolidin-1,3-diyl)diethanol] to act as ligands towards copper(II) was tested under different reaction conditions. These essays show that both HL 1 and H 3 L 2 are unstable in the presence of Cu II , suffering total imidazolidine ring...

Abstract The reaction of H4L (N,N′-bis(4-carboxysalicylidene)-1,3-propylenediamine) with CuII, NiII and CoII in a 1:1 ligand to metal molar ratio yields dinuclear [M(H2L)]2(H2O)n [M = Cu (1), Ni (2), Co (3); n = 0-2] complexes. Recrystallisation of 1 and 3 in methanol gives single crystals of the unaltered [Cu(H2L)]2 (1) and [Co(H2L)(HL′)]·4.25CH3O...

A rigid, one-dimensional, and monotopic ligand containing both a proton donor and a proton acceptor, 2-[(1Himidazol-2-yl)methyleneamino]phenol (H2L), has been used to attain three hierarchically assembled supramolecular polymers. The handedness of these hydrogen-bonded metallo-supramolecular structures is modulated by a selective coupling, via stro...

We have explored the use of steric hindrance for favouring/hindering the tautomerisation of Schiff bases (SB) into tetrahydroquinazolines (TQ) in two systems that derive from the condensation of 2 tosylaminobenzylamine with two different aldehydes: 2,3 dihydroxybenzaldehyde (H2L1SB/H2L1TQ) and N-(3-formylpyridin-2-yl)pivalamide (H2L2SB/H2L2TQ). The...

We report a synthetic approach towards metal complexes of the poorly coordinating sulfonamide 2-tosylaminomethylaniline (HLTs) that exploits both the good donor capacity of imine N atoms and the hydrolysis of imine ligands mediated by d-block metals. Zn2+, Cd2+ and Pd2+ ions appear to promote the efficient hydrolysis of a coordinated imine ligand (...

Pyridine-2, 6-dimethanol (H2L), a versatile donor acts as a neutral, monoanionic and dianionic coordination behaviour with two different coordination modes viz. tridentate and bidentate towards Cu(II) leading to three different geometric environments around Cu(II) centers. The single crystal X-ray structure reveals two different Cu(II) complexes wi...

We present a combined computational and experimental study of the possible conformations adopted by a ditopic Schiff base ligand based on triptycene. We have performed DFT calculations on a Y-shaped Schiff base ligand derived from the condensation of 2,6-diaminotriptycene and 2 hydroxybenzaldehyde to obtain the relative energies of their conformers...

Some reactivity in the oxidation of methanol to formaldehyde has been spectroscopically detected on the methanolic mother liquors of a copper(ii) complex of a Schiff base ligand derived from the condensation of 8-hydroxyquinoline-2-carboxaldehyde and 2-tosylaminomethylaniline. An investigation has shown that 2-tosylaminomethylaniline (HA(TS)) plays...

We have explored the use of steric hindrance on controlling the ring-chain tautomeric equilibrium of a tetrahydroquinazoline/imine system. Two imines, one of them having a bulky group (E)-N (3-((2-((4-methylphenylsulfonamido)methyl)phenylimino)methyl)pyridin-2-yl)pivalamide (H2L1SB) and the other one without bulky group (E)-N-(2-(2,3-dihydroxybenzy...

Density functional theory calculations and spectroscopic monitoring of the reactions of the chain tautomer N-{2-[(8-hydroxyquinolin-2-yl)methyleneamino]benzyl}-4-methylbenzene-sulfonamide (H2Lchain) and the ring tautomer 2-(3-tosyl-1,2,3,4-tetrahydroquinazolin-2-yl)quinolin-8-ol (H2Lring) against Zn(OAc)2•2H2O have been performed in order to clarif...

Both experimental and computational studies were undertaken to elucidate the formation process of 3-tosyl-1,2,3,4-tetrahydroquinazoline from methanolic mother liquors of Pd(LBS)·3H2O, where LBS is the dianionic form of the imine ligand N-{2-[(8-hydroxyquinolin-2-yl)methyleneamino]benzyl}-4-methylbenzenesulfonamide. Experimental studies have shown t...

The reaction of N'-[1-(pyridine-2-yl)ethylidene]acetohydrazide (L) with Cu(ClO4)2·6H2O in the presence of sodium dicyanamide affords an end-to-end one-dimensional coordination polymer, [CuL(μ1,3-N(CN)2]·ClO4, whose X-ray structure shows that the Cu II is bound by an N,N,O chelator and is bridged to two neighbouring metal centres by N(CN)2–, generat...

A hydroxo-bridged 1-D coordination polymer, [Cu(L)(H2O)]n (1), has been synthesized in good yield by employing a tetradentate Schiff base ligand, (6,6'-(1E,1'E)-(2-hydroxypropane-1,3-diyl)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(2-methoxyphenol)), generated by condensation of o-vanillin with 1,3-diaminopropane-2-ol. Compound 1 has been...

A decanuclear Cd complex has been found as a carbonate-containing capsule. The structure strongly resembles a ten-blade waterwheel with a central carbonate ligand surrounded by two superimposed Cd(5)O(5) crowns with a pentagonal antiprism-like disposition. The capsule is doubly capped by two pentadentate perchlorate anions.

The ring-chain tautomerism of 2-(3-tosyl-1,2,3,4-tetrahydroquinazolin-2-yl)quinolin-8-ol (H(2)L(ring)) has been exploited to produce mononuclear complexes or, alternatively, dinuclear complexes, as desired, by varying the stoichiometry of the ligand. Cu(2+) and Zn(2+) stabilise the ring tautomeric form of the ligand in their mononuclear complexes M...

The ring-chain tautomerism of a 2-aryl-1,2,3,4-tetrahydroquinazoline has been exploited to induce reversible changes in the aminal-imine equilibrium, as desired, by coordination of a suitable metal ion. This process was studied by NMR and UV-vis spectroscopies, X-ray crystallography, and molecular modeling approach. The results obtained show that t...

Nickel(II) and copper(II) acetate react with the trinucleating compartmental Schiff base H(4)L (H(4)L = 6,6'-(E)-3,3'-(ethane-1,2-diyl)bis(1-(2-((E)-3-bromo-5-chloro-2-hydroxybenzylideneamino)ethyl)imidazolidine-3,2-diyl)bis(2-bromo-4-chlorophenol)) to produce the heterotrinuclear complexes [Ni(2)CuL(OAc)(2)]·0.25H(2)O·2.5MeOH (1·0.25H(2)O·2.5MeOH)...

Ni(6) clusters of the general formula [{Ni(3)L(n)(OAc)(OH)}(2)(X)(OAc)(H(2)O)(2)] (n = 1, 2; X = Cl(-) or N(3)(-), (L(n))(3-) = hexadentate tritopic ligands) can be isolated by spontaneous self-assembly, from mixtures of Ni(OAc)(2), H(3)L(n), NMe(4)OH·5H(2)O and NaX in adequate molar ratios. Thus, four new hexanuclear complexes [{Ni(3)L(1)(OAc)(OH)...

Tautomer formation was discussed, the synthesis of the target compd. was achieved using 2-hydroxybenzaldehyde and N-[(2-aminophenyl)methyl]-4-methylbenzenesulfonamide as starting materials and the product thus obtained [i.e., N-[[2-[(E)-[(2-hydroxyphenyl)methylene]amino]phenyl]methyl]-4-methylbenzenesulfonamide] was confirmed by x-ray crystal struc...

Reactants pentaethylenehexamine (i.e., 3,6,9,12-tetraazatetradecane-1,14-diamine) and 3-bromo-5-chlorosalicylaldehyde were used, the synthesis of the target compd., i.e., bis[imidazolidine] Schiff base (E,E')-2,2'-[1,2-ethanediylbis[[2-(3-bromo-5-chloro-2-hydroxyphenyl)-3,1-imidazolidinediyl]-2,1-ethanediylnitrilomethylidyne]]bis[6-bromo-4-chloroph...

The crystal structures determined for [Zn2L1(acac)]·H2O and [Zn2L2(acac)]·H2O·MeCN·MeOH show that both compounds are chiral, although crystallising as racemates. This was not unexpected, as these complexes had been designed on the basis of the coordinating behaviour of acac in combination with 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabu...

The new complexes [(Cu2L1)2(p-OOC-C6H4-COO)]·7H2O (1·7H2O), [(Cu2L2)2(p-OOC-C6H4-COO)]·2H2O (2·2H2O), [(Cu2L1)2Cu(O2C-CH2-CO2)2]·9H2O (3·9H2O) and [(Cu2L2)2(OOC-CH2-COO)]·5.5H2O (4·5.5H2O) have been obtained by interaction of either [(Cu2L1)2(CO3)]·8H2O or [Cu2L2(OH)]·1.125H2O with the corresponding dicarboxylic acid. Recrystallisation of 1·7H2O in...

Mononuclear metal complexes of 2-[(2-hydroxyethylimino)methyl]quinolin-8-ol (H2L) were obtained by reaction of 8-hydroxyquinoline-2-carboxaldehyde, 2-aminoethanol and the corresponding metal(II) acetate (M = Co, Ni, Cu, Zn or Cd) in 2:2:1 molar ratios. The Schiff base ligand is acting as a monodeprotonated O,N,N-donor in the helical complex Ni(HL)2...