Synthesis of 6-formylpterin nucleoside analogs and their ROS generation activities in the presence of NADH in the dark

We demonstrated previously that 3-position-modified 6-formylpterin (6FP) derivatives produce reactive oxygen species (ROS) such as hydrogen peroxide (H(2)O(2)) from oxygen in the presence of NADH in the dark. It has been shown that 6FP derivatives markedly generate ROS, which gives rise to their particular physiological activities, such as induction of apoptosis in cellular and living systems, suggesting that such compounds provide a hint for the design of a ROS controlling agent in vivo. However, it is not well understood why such unique activities appear on chemical modification. In the present study, in order to see the effect on ROS generation activity in the dark by the modification of the 1-position in 6FP, we have developed a new synthetic procedure for nucleoside analogs of 6FP and prepared 1-(beta-d-ribofuranosyl)-2-(N,N-diethylaminomethyleneamino)-6-formylpteridin-4-one (RDEF) and 1-(beta-d-ribofuranosyl)-2-(piperidine-1-ylmethyleneamino)-6-formylpteridin-4-one (RPIF) in which the 1-position of 6FP is glycosylated. At pH 7.4, NADH was spontaneously oxidized to NAD(+) in the presence of RDEF in the dark. Using electron paramagnetic resonance analysis coupled with the spin trapping technique, we show that O(2) was converted to H(2)O(2)via superoxide anion radical ( O(2)(-)) during this reaction. The modification of the 1-position of 6FP did not cancel ROS generation activities, which were demonstrated in 3-position-modified 6FPs. Since the 6FP derivatives developed in the present study have a ribose moiety, these compounds can be subjected to further derivatization, such as incorporation into oligonucleotides, oligosaccharides, proteins, or any other compounds that recognize and interact with specific biomolecules, and therefore would be useful in pharmaceutical investigations that need generation of appropriate and controllable amounts of ROS in vivo.     

Aggregation tendency and reactivity toward AgX of cationic half-sandwich ruthenium(II) complexes bearing neutral N,O-ligands

The aggregation tendency of complexes [Ru(eta6-cymene)(N,O)Cl]X [N,O = 2-benzoylpyridine (2-bzpy), 1, and 2-acetylpyridine (2-acpy), 2, X- = BPh4- or PF6-] has been studied by means of PGSE NMR experiments. It was found that complexes with PF6- as counterion are mainly present in CD2Cl2 as ion pairs at low concentration, as a mixture of ion triples and free anions at medium concentration and as ion quadruples at elevated concentration. 19F, 1H-HOESY NMR experiments revealed that in ion triples and ion quadruples two cationic Ru-units pair up. Consistently, in the solid-state structure of 1PF6, determined through X-ray single-crystal investigation, two cationic Ru-units are held together by an intermolecular pi-pi stacking interaction between the pyridyl rings. Complexes having BPh4- as counterion are only present in solution as even aggregates, namely ion pairs at low concentration and ion quadruples at elevated concentration. In such a case a counteranion bridges two cationic Ru-units as observed in the solid-state structure of 1BPh4. The reactivity of complexes 1-2 toward AgX salts has been investigated in different solvents. Bicationic [Ru(eta6-cymene)(N,O)(MeCN)]X2 (N,O = 2-bzpy, 3, and 2-acpy, 4) and [Ru(MeCN)4(N,O)]X2 (N,O = 2-bzpy, 5, and 2-acpy, 6) complexes were obtained by the reaction of 1 and 2 with AgX in the presence of three equivalents of acetonitrile or in acetonitrile, respectively. The reaction of 1 with AgPF6 in acetone afforded complex [Ru(eta6-cymene)(N,O,O)]PF6 (7, where N,O,O = 4-alcoxide-4-phenyl-4-(pyridin-2-yl)butan-2-one) from the C-C coupling of a deprotonated methyl group of the coordinated acetone and the C=O moiety of 2-bzpy ligand.     

Lactam and acid amide acetals. 64. Acylation of enamino ketones of the indolin-3-one and 2-pyrrolin-4-one series and synthesis of 2-indolyl- and 5-pyrrolylacrylic acid derivatives

The reaction of 2-(N,N-dimethylaminomethylene)indolin-3-one and 2-methyl-3-ethoxycarbonyl-5-(N,N-dimethyl aminomethylene)-2-pyrrolin-4-one with acyl halides was used to synthesize immonium salts, the aqueous hydrolysis of which leads to 2-formyl-3-hydroxyindole and 4-hydroxy-5 formylpyrrole derivatives. -Cyano--(2-indolyl)- and -cyano--(5-pyrrolyl)acrylic acid derivatives were synthesized by reaction of immonium salts of the pyrrole series, 4 acyloxy-5-formylpyrrole and 2-formyl-3-acyloxyindole derivatives, with compounds that contain an active methylene group.See [1] for Communication 63.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 343–348, March, 1991.     

Solvent-induced <Emphasis Type="Italic">E/Z</Emphasis>(C=N)-isomerization of imines of some hydroxy-substituted formylcoumarins

Aromatic imines, namely, 5-formyl-6-hydroxy-4-methyl- and 8-formyl-7-hydroxy-4-methylcoumarin derivatives, have been synthesized. A dependence of their spectral characteristics (¹H NMR spectra, electronic absorption spectra) from the solvent (DMSO, CHCl₃, DMF, acetonitrile, MeOH) has been studied. The solvatochromic effects observed for a number of imines, first of all, for 7-hydroxy-4-methyl-8-(4′-nitrophenylimino)methyl-2H-1-benzopyran-2-one, were related to their E/Z-isomerization with respect to the C=N bond based on the quantum chemical calculations by the AM1, PM3, PPP CI methods. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1954–1960, September, 2008.     

Synthesis, spectral, thermal and magnetic studies of Mn(II), Ni(II) and Cu(II) complexes with some benzopyran-4-one Schiff bases

The Schiff bases of N(2)O(2) dibasic ligands, H(2)La and H(2)Lb are prepared by the condensation of ethylenediamine (a) and trimethylenediamine (b) with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one. Also tetra basic ligands, H(4)La and H(4)Lb are prepared by the condensation of aliphatic amines (a) and (b) with 6-formyl-5,7-dihydroxy-2-methylbenzopyran-4-one. New complexes of H(4)La and H(4)Lb with metal ions Mn(II), Ni(II) and Cu(II) are synthesized, in addition Mn(II) complexes with ligands H(2)La and H(2)Lb are also synthesized. Elemental and thermal analyses, infrared, ultraviolet-visible as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The structures of copper(II) complexes are also assigned based upon ESR spectra study. All the complexes separated with the stoichiometric ratio (1:1) (M:L) except Mn-H(4)La and Mn-H(4)Lb with (2:1) (M:L) molar ratio. In metal chelates of the type 1:1 (M:L), the Schiff bases behave as a dinegative N(2)O(2) tetradentate ligands. Moreover in 2:1 (M:L) complexes, the Schiff base molecules act as mono negative bidentate ligand and binuclear complex is then formed. The Schiff bases were assayed by the disc diffusion method for antibacterial activity against Staphylococcus aureus and Escherichia coli. The antifungal activity of the Schiff bases was also evaluated against the fungi Aspergillus flavus and Candida albicans.     

Photoluminescence of the Coordination Zinc Compounds with 3-Methyl-4-Formyl-1-Phenylpyrazol-5-one Acylhydrazones

Russian Journal of Coordination Chemistry - New coordination zinc compounds based on 3-methyl-4-formyl-1-phenylpyrazol-5-one acylhydrazones [Zn(L)(CH3COO)Solv] (Solv is H2O (I), Py (II)) are...     

Four component tandem Knoevenagel–Michael strategy for the assembly of arylaldehydes,N,N'-dimethylbarbituric acid, 4-hydroxy-6-methyl-2H-pyran-2-one and morpholine into unsymmetrical scaffold with three different heterocyclic rings

A new type of four component tandem Knoevenagel–Michael reaction has been found consisting in the assembly of benzaldehydes, N,N'-dimethylbarbituric acid, 4-hydroxy-6-methyl-2H-pyran-2-one and morpholine in alcohols, other organic solvents or water at room temperature without catalyst or any other additives, which results in the selective formation of unsymmetrical scaffold with three different heterocyclic rings in 63–98% yields. The crystal structure of morpholinium 5-[(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)(4-nitrophenyl)methyl]-1,3-dimethyl-2,6-dioxo-1,2,3,4-tetrahydropyrimidin-6-olate has been confirmed by X-ray diffraction.     

Effect of water on product yields of 2-azidobenzoic acid photolysis in aprotic solvents

The effect of water admixtures on the formation of 2-oxo-(3H)-azepine-3-carboxylic acid and 2,1-benzisoxazol-3(1H)-one in the photolysis of 2-azidobenzoic acid in aprotic solvents has been investigated. It has been shown that the addition of nucleophilic agents to the reaction mixture determines the yields of not only 3H-azepines, the products of benzene ring expansion, but also the intramolecular cyclization product 2,1-benzisoxazol-3(1H)-one. Participation of the formed 2,1-benzisoxazol-3(1H)-one in the reaction has been suggested as an explanation of the effect of nucleophilic compounds (water, ethanol, and 2,1-benzisoxazol-3(1H)-one) on the product yield of the monomolecular reaction.     

Efficient catalytic interconversion between NADH and NAD+ accompanied by generation and consumption of hydrogen with a water-soluble iridium complex at ambient pressure and temperature

Regioselective hydrogenation of the oxidized form of β-nicotinamide adenine dinucleotide (NAD(+)) to the reduced form (NADH) with hydrogen (H(2)) has successfully been achieved in the presence of a catalytic amount of a [C,N] cyclometalated organoiridium complex [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(H(2)O)](2) SO(4) [1](2)·SO(4) under an atmospheric pressure of H(2) at room temperature in weakly basic water. The structure of the corresponding benzoate complex Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))-benzoate-κC(3))(H(2)O) 2 has been revealed by X-ray single-crystal structure analysis. The corresponding iridium hydride complex formed under an atmospheric pressure of H(2) undergoes the 1,4-selective hydrogenation of NAD(+) to form 1,4-NADH. On the other hand, in weakly acidic water the complex 1 was found to catalyze the hydrogen evolution from NADH to produce NAD(+) without photoirradiation at room temperature. NAD(+) exhibited an inhibitory behavior in both catalytic hydrogenation of NAD(+) with H(2) and H(2) evolution from NADH due to the binding of NAD(+) to the catalyst. The overall catalytic mechanism of interconversion between NADH and NAD(+) accompanied by generation and consumption of H(2) was revealed on the basis of the kinetic analysis and detection of the catalytic intermediates.     

Voltammetric studies on the reduction of polyoxometalate anions in ionic liquids

The electrochemical reduction of tetrabutylammonium salts of isostructural pairs of polyoxometalates [Bu4N]2[M6O19], [Bu4N]4[alpha-SiM12O40], and [Bu4N]4[alpha-S2M18O62] (M = Mo or W) has been investigated at glassy carbon electrodes in dissolved and surface-confined states in ionic liquids and other media. In the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF(6)], between two and six reversible one-electron-transfer processes were detected. Detailed studies on the process [alpha-S2W18O62](4-/5-) in a range of ionic liquids, water, and conventional organic solvents (containing 0.1 M electrolyte) suggest that the polarity of the medium plays a key role in the determination of the reversible potential. Reduction processes involving very highly charged [alpha-S2W18O62](8-/9-/10-) species are strongly influenced by the purity of the medium.     

Synthesis,characterization and antibacterial activity of some new complexes of Cu(II), Ni(II), VO(II), Mn(II) with Schiff base derived from 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one

Coordination compounds of Cu(II), VO(II), Ni(II), and Mn(II) with the Schiff base obtained through the condensation of 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one with 3-formyl-6-methyl-chromone were synthesized. The characterization of the newly formed compounds was done by ¹H NMR, UV–Vis, IR, ESR spectroscopy, elemental analysis and molar electric conductibility. The crystal structure of 1-phenyl-2,3-dimethyl-4-(N-3-formyl-6-methyl-chromone)-3-pyrazolin-5-one (HL) has been determined by X-ray diffraction studies, as well as the one of its copper(II) complex [CuL(OAc)]·CH₃OH which contains an anionic ligand and an acetate in the coordination sphere of the metal. The single crystal X-ray structure for (HL) was analyzed for its various weak H-bonding and dimeric association.     

Substitution and derivatization reactions of a water soluble iron(II) complex containing a self-assembled tetradentate phosphine ligand

Facile substitution reactions of the two water ligands in the hydrophilic tetradentate phosphine complex cis-[Fe{(HOCH2)P{CH2N(CH2P(CH2OH)2)CH2}2P(CH2OH)}(H2O)2](SO4) (abbreviated to [Fe(L1)(H2O)2](SO4), 1) take place upon addition of Cl-, NCS-, N3(-), CO3(2-) and CO to give [Fe(L1)X2] (2, X = Cl; 4, X = NCS; 5, X=N3), [Fe(L1)(kappa2-O(2)CO)], 6 and [Fe(L1)(CO)2](SO4), 7. The unsymmetrical mono-substituted intermediates [Fe(L1)(H2O)(CO)](SO(4)) and [Fe(L(1))(CO)(kappa(1)-OSO(3))] (8/9) have been identified spectroscopically en-route to 7. Treatment of 1 with acetic anhydride affords the acylated derivative [Fe{(AcOCH2)P{CH2N(CH2P(CH2OAc)2)CH2}2P(CH2OAc)}(kappa2-O(2)SO2)] (abbreviated to [Fe(L2)(kappa2-O(2)SO2)], 10), which has increased solubility over 1 in both organic solvents and water. Treatment of 1 with glycine does not lead to functionalisation of L1, but substitution of the aqua ligands occurs to form [Fe(L(1))(NH(2)CH(2)CO(2)-kappa(2)N,O)](HSO(4)), 11. Compound 10 reacts with chloride to form [Fe(L(2))Cl(2)] 12, and 12 reacts with CO in the presence of NaBPh4 to form [Fe(L2)Cl(CO)](BPh4) 13b. Both of the chlorides in 12 are substituted on reaction with NCS- and N3(-) to form [Fe(L2)(NCS)2] 14 and [Fe(L2)(N3)2] 15, respectively. Complexes 2.H2O, 4.2H2O, 5.0.812H2O, 6.1.7H2O, 7.H2O, 10.1.3CH3C(O)CH3, 12 and 15.0.5H2O have all been crystallographically characterised.     

Bicyclic monoterpenoids of the essential oil of Ledum palustre

The structure of a new natural compound has been established as 5-isopropylbicyclo[3.1.0]hex-3-en-2-one, which has been called lebaikon. Two bicyclic monoterpenoids (2-formyl-5-isopropylbicyclo[3.1.0]hex-2-ene and 4-isopropyl-1-methylbicyclo[3.1.0]hexan-2-one) have been detected in natural materials for the first time.     

On the synthesis of ecdysone. IV. On insect hormones. The synthesis of the natural skin shedding hormone

Ecdysone ( 9 ), a hormone responsible for the skin shedding process of arthropoda, has been synthesized. (20S)-2β,3β-Diacetoxy-20-formyl-5β-pregn-7-en-6-one was prepared from the corresponding carboxylic acid and converted into ecdysone by a GRIGNARD reaction with 2-methyl-3-butyn-2-ol tetrahydropyran-2-yl ether, followed by hydrogenation of the triple bond, removal of the protecting groups, and hydroxylation in the 14α-position. C-22-isoecdysone was obtained as a by-product.     

The synthesis, structure and ethene polymerisation catalysis of mono(salicylaldiminato) titanium and zirconium complexes

The silyl ethers 3-But-2-(OSiMe3)C6H3CH=NR (2a-e) have been prepared by deprotonation of the known iminophenols (1a-e) and treatment with SiClMe3 (a, R = C6H5; b, R = 2,6-Pri2C6H3; c, R = 2,4,6-Me3C6H2; d, R = 2-C6H5C6H4; e, R = C6F5). 2a-c react with TiCl4 in hydrocarbon solvents to give the binuclear complexes [Ti{3-But-2-(O)C6H3CH=N(R)}Cl(mu-Cl3)TiCl3] (3a-c). The pentafluorophenyl species 2e reacts with TiCl4 to give the known complex Ti{3-But-2-(O)C6H3CH=N(R)}2Cl2. The mononuclear five-coordinate complex, Ti{3-But-2-(O)C6H3CH=N(2,4,6-Me3C6H2)}Cl3 (4c), was isolated after repeated recrystallisation of 3c. Performing the dehalosilylation reaction in the presence of tetrahydrofuran yields the octahedral, mononuclear complexes Ti{3-But-2-(O)C6H3CH=N(R)}Cl3(THF) (5a-e). The reaction with ZrCl4(THF)2 proceeds similarly to give complexes Zr{3-But-2-(O)C6H3CH=N(R)}Cl3(THF) (6b-e). The crystal structures of 3b, 4c, 5a, 5c, 5e, 6b, 6d, 6e and the salicylaldehyde titanium complex Ti{3-But-2-(O)C6H3CH=O}Cl3(THF) (7) have been determined. Activation of complexes 5a-e and 6b-e with MAO in an ethene saturated toluene solution gives polyethylene with at best high activity depending on the imine substituent.     

Naphthylimido-substituted hexamolybdate: preparation, crystal structures, solvent effects, and optical properties of three polymorphs

[(n-C4H9)4N]2[Mo6O18(N-1-C10H(6)-2-CH3)] (1) has been prepared by the reaction of 1-amino-2-methylnaphthalene hydrochloride with [(n-C4H9)4N]4[alpha-Mo8O26] in the presence of 1,3-dicyclohexylcarbodiimide. Three solvent-free crystalline phases are isolated from the mixed solvents of acetone and acetic ether. The X-ray single-crystal structures of the three phases have been determined, showing the packing and supramolecular assembly characters (pseudohigher symmetry, helical chains, and pi-pi stacking) by which the effect of solvent polarity and crystallization speed on polymorphism in organic-inorganic hybrids has been demonstrated.     

Guanine-containing copper(II) complexes: synthesis, X-ray structures and magnetic properties

Three new compounds of formula {[Cu(gua)(H(2)O)(3)](BF(4))(SiF(6))(1/2)}(n) (1), {[Cu(gua)(H(2)O)(3)](CF(3)SO(3))(2).H(2)O}(n) (2) and [Cu(gua)(2)(H(2)O)(HCOO)]ClO(4).H(2)O.1/2HCOOH] (3) [gua = 2-amino-1H-purin-6(9H)-one] showing the unprecedented coordination of neutral guanine, have been synthesised and structurally characterized. The structures of the compounds 1 and 2 contain uniform copper(II) chains of formula [Cu(gua)(H(2)O)(3)](n)(2n+), where the copper atoms are bridged by guanine ligands coordinated via N(3) and N(7). The electroneutrality is achieved by uncoordinated tetrafluoroborate and hexafluorosilicate (1) and triflate (2). Each copper atom in 1 and 2 is five-coordinated in a distorted square pyramidal environment: two water molecules in trans positions and the N(3) and N(7a) nitrogen atoms of two guanine ligands build the basal plane whereas a water molecule fills the axial position. The values of the copper-copper separation across the bridging guanine ligand are 7.183(1) (1) and 7.123(1) A (2). is an ionic salt whose structure is made up of mononuclear [Cu(gua)(2)(H(2)O)(HCOO)](+) cations and perchlorate anions plus water and formic acid as crystallization molecules. The two guanine ligands in the cation are coordinated to the copper centre through the N(9) atom. The copper atom in 3 is four-coordinated with two monodentate guanine molecules in the trans position, a water molecule and a monodenate formate ligand building a quasi square planar surrounding. Magnetic susceptibility measurements for 1 and 2 in the temperature range 1.9-300 K show the occurrence of significant intrachain antiferromagnetic interactions between the copper(ii) ions across the guanine bridge [J = -9.6(1) (1) and -10.3(1) cm(-1) (2) with H = -J summation operator(i)S(i).S(i+1)].     

Selectivity of purine alkylation by a quinone methide. Kinetic or thermodynamic control?

The alkylation reaction of 9-methyladenine and 9-methylguanine (as prototype substrates of deoxy-adenosine and -guanosine), by the parent o-quinone methide (o-QM), has been investigated in the gas phase and in aqueous solution, using density functional theory at the B3LYP/6-311+G(d,p) level. The effect of the medium on the reactivity, and on the stability of the resulting adducts, has been investigated by using the C-PCM solvation model to assess which adduct arises from the kinetically favorable path, or from an equilibrating process. The calculations indicate that the most nucleophilic site of the methyl-substituted nucleobases in the gas phase is the guanine oxygen atom (O(6)) (DeltaG()(gas) = 5.6 kcal mol(-)(1)), followed by the adenine N1 (DeltaG)(gas) = 10.3 kcal mol(-)(1)), while other centers exhibit a substantially lower nucleophilicity. The bulk effect of water as a solvent is the dramatic reduction of the nucleophilicity of both 9-methyladenine N1 (DeltaG)(solv) = 14.5 kcal mol(-)(1)) and 9-methylguanine O(6) (DeltaG)(solv) = 17.0 kcal mol(-)(1)). As a result there is a reversal of the nucleophilicity order of the purine bases. While O(6) and N7 nucleophilic centers of 9-methylguanine compete almost on the same footing, the reactivity gap between N1 and N7 of 9-methyladenine in solution is highly reduced. Regarding product stability, calculations predict that only two of the adducts of o-QM with 9-methyladenine, those at NH(2) and N1 positions, are lower in energy than reactants, both in the gas phase and in water. However, the adduct at N1 can easily dissociate in water. The adducts arising from the covalent modification of 9-methylguanine are largely more stable than reactants in the gas phase, but their stability is markedly reduced in water. In particular, the oxygen alkylation adduct becomes slightly unstable in water (DeltaG(solv) = +1.4 kcal mol(-)(1)), and the N7 alkylation product remains only moderately more stable than free reactants (DeltaG(solv) = -2.8 kcal mol(-)(1)). Our data show that site alkylations at the adenine N1 and the guanine O(6) and N7 in water are the result of kinetically controlled processes and that the selective modification of the exo-amino groups of guanine N2 and adenine N6 are generated by thermodynamic equilibrations. The ability of o-QM to form several metastable adducts with purine nucleobases (at guanine N7 and O(2), and adenine N1) in water suggests that the above adducts may act as o-QM carriers.     

Hydration to benzo-15-crown-5, benzo-18-crown-6 and the benzo-18-crown-6-potassium ion complex in the low-polar organic solvents.

The coextraction of water with benzo-15-crown-5 (B1SC5), benzo-18-crown-6 (B18C6) and the B18C6-K+ complex into seven low-polar solvents, i.e., carbon tetrachloride (CTC), chloroform (CF), dichloromethane (DCM), 1,2-dichloroethane (1,2-DCE), benzene (BZ), chlorobenzene (CB) and o-dichlorobenzene (o-DCB), has been investigated. The mean hydration number, nH2O, of these solutes in the water-saturated organic solvents was determined. There is a trend that the nH2O values for any solutes increase with increasing the water concentration in the solvents. Those of B18C6 and B15C5 converge at almost 0.8 for B18C6 and 0.4 - 0.5 for B15C5 in the solvents with the relatively high water concentration, i.e., CF, 1,2-DCE, DCM, and nitorobenzene (NB). The nH2O value of B15C5 is about one-half of that of B18C6 for a given organic solvent. The dominant species of the B18C6-K+ complex in these solvents is non-hydrated. From these results, the hydration equilibrium constants, KH2O, in the organic solvents were estimated.     

A 1,8-naphthalenediol-based unsymmetrical dinucleating ligand

A facile synthesis of 2-formyl-1,8-naphthalenediol is reported. Its potential as a general precursor for the preparation of unsymmetrical multidentate chelating ligand systems based on 1,8-naphthalenediol is demonstrated by the synthesis of the dinucleating ligand L(4-)(H(4)L=N,N'-bis(2-(1,8-naphthalenediol)methylidene)propylenediamine). Reaction of H(4) L with copper acetate results in the formation of the unsymmetrical dinuclear Cu(II) complex [LCu(2)](3), which has been structurally characterized by single-crystal X-ray diffraction. One Cu(II) ion is coordinated by a N(2)O(2) compartment of L(4-) and the other Cu(II) ion is coordinated by an O(4) compartment of L(4-) while they are bridged by two aryloxide functions of L(4-). A dimerization of two molecules of 3 to a tetranuclear entity 3(2) occurs through formation of weak apical Cu--O interactions. Analysis of the temperature dependent magnetic susceptibility measurements (2--290 K) established a strong intradimer exchange coupling J(12)=-371 cm(-1). This strong superexchange interaction fits nicely in a magneto-structural correlation which has been established for dinuclear bis(phenoxide)-bridged Cu(II) complexes demonstrating the electronic equivalence of the aryloxides of a phenol and 1,8-naphthalenediol.