bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of overexpression of wild‐type or mutant parkin on the cellular response induced by toxic insults
Authors: Hyun Dong‐Hoon , Lee MoonHee , Halliwell Barry , Jenner Peter 
Published: August 2005

AbstractMutations in parkin are involved in some cases of autosomal recessive juvenile parkinsonism (AR‐JP), but it is not known how they result in nigral cell death. We examined the effect of parkin overexpression on the response of cells to various insults. Wild‐type and AR‐JP‐associated mutant parkins (Del3‐5, T240R, and Q311X) were overexpressed in NT‐2 and SK‐N‐MC cells. Overexpressed wild‐type parkin delayed cell death induced by serum withdrawal, H2O2, 1‐methyl‐4‐phenylpyridinium (MPP+), or 4‐hydroxy‐2‐trans‐nonenal (HNE) but did not delay cell death caused by the proteasome inhibitor lactacystin. Increases in damage to proteins (protein carbonyls and 3‐nitrotyrosine) were attenuated by wild‐type parkin after serum withdrawal or exposure to H2O2, MPP+, or HNE but not after exposure to lactacystin. The mutant parkins (of all types) markedly accelerated cell death in response to all the insults, accompanied by increased levels of 8‐hydroxyguanine, protein carbonyls, lipid peroxidation, and 3‐nitrotyrosine and decreased levels of GSH. The viability loss induced by all the insults showed apoptotic features. The presence of parkin mutations in substantia nigra in Parkinson's disease may increase neuronal vulnerability to a range of toxic insults. © 2005 Wiley‐Liss, Inc.
Maximal vertex‐connectivity of $\overrightarrow{S_{n,k}}$
Authors: Cheng Eddie , Lindsey William A. , Steffy Daniel E. 
Published: August 2005

AbstractThe class of star graphs is a popular topology for interconnection networks. However, it has certain deficiencies. A class of generalization of star graphs called (n,k)‐star graphs was introduced by Chiang and Chen to address these issues. In this article we will consider the vertex‐connectivity of the directed (n,k)‐star graph,$\overrightarrow{S_{n,k}}$, given by Cheng and Lipman,8, and show that it is maximally connected. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 46(3), 154–162 2005
Enhanced thermal stability achieved without increased conformational rigidity at physiological temperatures: Spatial propagation of differential flexibility in rubredoxin hybrids
Authors: LeMaster David M. , Tang Jianzhong , Paredes Diana I. , Hernández Griselda 
Published: August 2005

AbstractThe extreme thermal stability of proteins from hyperthermophilic organisms is widely believed to arise from an increased conformational rigidity in the native state. In apparent contrast to this paradigm, both Pyrococcus furiosus (Pf) rubredoxin, the most thermostable protein characterized to date, and its Clostridium pasteurianum (Cp) mesophile homolog undergo a transient conformational opening of their multi‐turn segments, which is more favorable in hyperthermophile proteins below room temperature. Substitution of the hyperthermophile multi‐turn sequence into the mesophile protein sequence yields a hybrid, (14–33Pf) Cp, that exhibits a 12° increase in its reversible thermal unfolding transition midpoint. Nuclear magnetic resonance (NMR) magnetization transfer‐based hydrogen exchange was used to monitor backbone conformational dynamics in the subsecond time regime. Despite the substantially increased thermostability, flexibility throughout the entire main chain of the more thermostable hybrid is equal to or greater than that of the wild type mesophile rubredoxin near its normal growth temperature. In comparison to the identical core residues of the (14–33Pf) Cp rubredoxin hybrid, six spatially clustered residues in the parental mesophile protein exhibit a substantially larger temperature dependence of exchange. The exchange behavior of these six residues closely matches that observed in the multi‐turn segment, consistent with a more extensive conformational process. These six core residues exhibit a much weaker temperature dependence of exchange in the (14–33Pf) Cp hybrid, similar to that observed for the multi‐turn segment in its parental Pf rubredoxin. These results suggest that differential temperature dependence of flexibility can underlie variations in thermostability observed for mesophile versus hyperthermophile homologs. Proteins 2005. © 2005 Wiley‐Liss, Inc.
QND theory of long range forces in AFM on Au(111) [phys. stat. sol. (b) Vol. 242, No. 12, R103–R105 (2005)]
Authors: Drakova D. , Doyen G. 
Published: August 2005

AbstractThe misprint of two sentences on page R105 is corrected.See original phys. stat. sol. (b) Vol. 242, No. 12, R103–R105 (2005)(© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resultants and loop closure
Authors: Coutsias Evangelos A. , Seok Chaok , Wester Michael J. , Dill Ken A. 
Published: August 2005

AbstractThe problem of tripeptide loop closure is formulated in terms of the angles {τi}describing the orientation of each peptide unit about the virtual axis joining theCαatoms. Imposing the constraint that at the junction of two such units the bond angle between the bondsCαNandCαCis fixed at some prescribed value θ results in a system of three bivariate polynomials inui≔ tan τi/2 of degree 2 in each variable. The system is analyzed for the existence of common solutions by making use of resultants, determinants of matrices composed of the coefficients of two (or more) polynomials, whose vanishing is a necessary and sufficient condition for the polynomials to have a common root. Two resultants are compared: the classical Sylvester resultant and the Dixon resultant. It is shown that when two of the variables are eliminated in favor of the third, a polynomial of degree 16 results. To each one of its real roots, there is a corresponding common zero of the system. To each such zero, there corresponds a consistent conformation of the chain. The Sylvester method can find these zeros among the eigenvalues of a 24 × 24 matrix. For the Dixon approach, after removing extraneous factors, an optimally sized eigenvalue problem of size 16 × 16 results. Finally, the easy extension to the more general problem of triaxial loop closure is presented and an algorithm for implementing the method on arbitrary chains is given. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Automated derivation and parallel computer implementation of renormalized and active‐space coupled‐cluster methods
Authors: Piecuch Piotr , Hirata So , Kowalski Karol , Fan Peng‐Dong , Windus Theresa L. 
Published: August 2005

AbstractOur recent efforts that have led to an automated derivation and computer implementation of the renormalized and active‐space coupled‐cluster (CC) methods with Tensor Contraction Engine (TCE) are summarized. The TCE‐generated renormalized and active‐space CC computer codes are parallel and applicable to closed‐ and open‐shell references, enabling accurate calculations of potential energy surfaces along bond‐breaking coordinates and excited states displaying a significant multi‐reference character. The effectiveness of the new codes in describing electronic quasi‐degeneracies is illustrated by the renormalized CC calculations of the potential energy curve of HCl and the active‐space CC calculations for the low‐lying excited states of the Be3 system. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
The Cadmium Oxide Route to Alkali Metal Oxometallates with Uncommon Structural Features
Authors: Möller Angela 
Published: August 2005

AbstractThe aim of this research report is to give an introduction to a specific solid state reaction applied in the field of alkali metal rich transition metal compounds. The approach is an explorative investigation of the oxidation of transition metals with CdO in the presence of alkali metal oxides and / or compounds with complex anions such as Na2SO4. Thereby, a range of unusual compounds have been obtained and structurally characterized. In particular, low valences and uncommon coordination numbers (C.N.) of the late 3d transition metals, as well as interesting varieties in the anionic part of the structures are accessible. The presented examples were selected mainly in order of their inherent aspects concerning the reactivity, structural features or electronic structures.
Synthesis and Crystal Structure of Two New Molydenum(V) Pyrophosphate Complexes
Authors: Li Qi , Zhang Shi‐Wei 
Published: August 2005

AbstractTwo new reduced molybdenum pyrophosphates, Na28[Na2{(Mo2O4)10(P2O7)10(HCOO)10}]·108H2O (1) and Na22(H3O)2[Na4{(Mo2O4)10(P2O7)10(CH3COO)8(H2O)4}]·91H2O (2) have been synthesized and characterized by single‐crystal X‐ray diffraction. Red crystals of 1 are triclinic, space group $P{\bar 1}$, with a = 17.946(4) Å, b = 18.118(4) Å, c = 21.579(4) Å, α = 114.47(3)°, β = 93.54(3)°, γ = 114.39(3)° and V = 5581.8(19) Å3, and orange crystals of 2 are monoclinic, space group P21/n, with a = 21.467(4) Å, b = 23.146(5) Å, c = 24.069(5) Å, β = 101.76(3)° and V = 11708(4) Å3. They are both constructed by MoV dimers ({Mo2O4(OP)4(HCOO)} in 1, {Mo2O4(OP)4(CH3COO)} and {Mo2O4(OP)4(H2O)2} in 2) and pyrophosphoric groups. Their structures can be described as two interconnected nonequivalent wheels which are approximately perpendicular, delimiting a large cavity. The larger wheel contains six MoV dimers, while the smaller one has four dimers.
Fixierung von CO2 durch Pyrazolylborat‐Zink‐Hydroxid‐Komplexe
Authors: Peter Andrea , Vahrenkamp Heinrich 
Published: August 2005

AbstractFixation of CO2 by Pyrazolylborate‐Zinc‐Hydroxide ComplexesThe reversible uptake of CO2 by Tp*Zn‐OH complexes in alcoholic solutions with formation of Tp*Zn‐alkylcarbonate complexes was subjected to a comparative study. Its rate and the stability of its products depend on (1) the substituents in the 3‐positions of the pyrazolylborates (phenyl ≈ 3‐pyridyl ≫ t‐butyl), (2) the alcohol (CH3OH > C2H5OH). Traces of water seem to be essential for the formation of the Tp*Zn‐alkylcarbonates. In solution these are only stable in the presence of CO2. Two new alkylcarbonate complexes were obtained and characterized by structure determinations.
Solvothermal Synthesis and Crystal Structure of One‐Dimensional Chains of Anhydrous Zinc and Magnesium Formate
Authors: Viertelhaus Martin , Anson Christopher E. , Powell Annie K. 
Published: August 2005

AbstractReaction of the zinc or magnesium formate dihydrates in formic acid under solvothermal conditions results in the formation of single crystals of the anhydrous metal(II) formates β‐Zn(OOCH)2 and β‐Mg(OOCH)2. Both structures form one‐dimensional chains of μ‐oxygen‐bridged metal atoms. Single crystal diffraction studies reveal that β‐zinc formate represents the first structure in which chains of oxygen‐bridged metal atoms are connected by alternating single, double and triple oxygen atom bridges resulting in the first observation of corner, edge and face sharing coordination octahedra within a single chain. Polycrystalline material can be obtained by dehydration reaction of zinc formate dihydrate. β‐magnesium formate is the crystalline product that is obtained by annealing the amorphous intermediate phase after dehydration of magnesium formate dihydrate.
Reactive E=C(p‐p)π‐Systems. 55. [1] Ligand Properties of 1‐Trifluoromethyl‐2‐diethylamino‐2‐fluoro‐1‐arsaethene, F3CAs=C(F)NEt2
Authors: Albers Thomas , Grobe Joseph 
Published: August 2005

AbstractDue to the mesomeric interaction of the nitrogen lone pair with the As=C double bond, the perfluoroarsapropene derivative F3CAs=C(F)NEt2 (1) is sufficiently stable to serve as a ligand in transition metal carbonyl complexes. 1 was coordinated to chromium by reaction with the photochemically generated labile complex Cr(CO)5(THF), yielding the monosubstituted pentacarbonyl derivative Cr(CO)5[F3CAs=C(F)NEt2] (2). Already at room temperature, this is slowly transformed into the binuclear complex [F3CAs=C(F)NEt2][Cr(CO)5]2 (3) by replacing 1 from a neighbouring molecule by the stronger donor 2. In a closed system 3 obviously exists in an equilibrium with 1 and 2. Both complexes are related to the previously studied derivatives of the 2‐dimethylamino‐perfluoro‐1‐phosphapropene ligand. The products were identified by spectroscopic (IR, NMR) investigations and comparison with the related phosphaalkene complexes.
Beiträge zur Kristallchemie und zum thermischen Verhalten von wasserfreien Phosphaten. XXXVI [1] Synthese, Kristallstruktur und spektroskopische Charakterisierung von Palladium(II)‐diphosphat Pd2P2O7
Authors: Panagiotidis K. , Glaum R. , Schmedt auf der Günne J. , Hoffbauer W. , Görzel H. 
Published: August 2005

AbstractSynthesis, Crystal Structure and Spectroscopical Characterization of Palladium(II)‐Diphosphate Pd2P2O7Pd2P2O7 is synthesized by heating (Tmax = 500 °C) stoichiometric amounts of PdO and phosphoric acid. Using chemical vapour transport experiments (850 °C → 750 °C, addition of PdCl2) Pd2P2O7 was crystallized. Pd2P2O7 adopts its own structure type (C 2/c (No. 15), Z = 4, a = 13,151(2) Å, b = 5,172(1) Å, c = 8,139(1) Å, β = 97,52(1)°, 1160 independent reflections, 55 variables, R1 = 0,021 and wR2 = 0,050). Square‐planar [PdO4]‐units $({\bar d}\rm (Pd-O)=2,020 \AA)$ are linked by diphosphate‐groups generating a 3D framework. Within this framework ribbons $^{1}_{\infty}\rm[Pd(P_{2}O_{7})]^{2-}$ may be distinguished. Thus Pd2P2O7 might be described as palladium(II)‐[diphosphatopalladate(II)].The results of various spectroscopic measurements (IR, Raman, UV/VIS, 31P‐MAS‐NMR) are reported and discussed within the context of the crystal structure.
Rietveld Analysis of a High Pressure Modification of Monocalcium Oxogallate (CaGa2O4)
Authors: Lazić Biljana , Kahlenberg Volker , Konzett Jürgen 
Published: August 2005

AbstractA high‐pressure modification of monocalcium gallate (CaGa2O4) has been prepared in a piston‐cylinder apparatus at 700 °C and 4.0 GPa. The compound is orthorhombic (space group Pnam, a = 9.12476(15) Å, b = 10.56093(18) Å, c = 2.98547(4) Å, V = 287.70(1) Å3, Z = 4, Dcalc = 5.62 g/cm3) and belongs to the CaFe2O4‐type structure family. The structure was refined by the Rietveld method using laboratory X‐ray powder diffraction data. Two crystallographically independent GaO6‐octahedra forming edge‐sharing double chains can be distinguished. The shared edges exhibit a considerable shortening. The chains are running parallel to the c‐axis and are linked by corner‐sharing. They enclose tunnels in which the calcium atoms are located for charge compensation. Each calcium cation has eight nearest oxygen neighbors. The coordination environment can be described as a bicapped trigonal prism.
Layer and Cavity Structures of Manganese(II) Diphenate Coordination Polymers
Authors: Lian Fenyan , Wang Ruihu , Han Lei , Jiang Feilong , Hong Maochun 
Published: August 2005

AbstractTwo novel metal‐organic coordination polymers, [Mn2(dpa)2(4,4′‐bipy)2(H2O)2]n (1) and [Mn(Hdpa)2(bpe)(H2O)2]n (2) (H2dpa = diphenic acid, 4,4′‐bipy = 4,4′‐dipyridine, bpe = 1,2‐bis(4‐pyridyl)ethene), have been hydrothermally synthesized. Single crystal X‐ray diffraction analyses reveal the two‐dimensional and three‐dimensional structures for complexes 1 and 2, respectively. In 1, the dpa ligands link metal ions with different modes into one‐dimensional chains, and the 4,4′‐bipy terminally coordinate to the metal ions extending the chains into a layer. Whereas in 2, the flexible bpe ligands link the structure motifs into chains, and the hydrogen bonding interactions between the chains lead to the formation of cavity structure.
Crystal Structures, Dimorphism and Lithium Mobility of Li7MO6 (M = Bi, Ru, Os)
Authors: Mühle Claus , Karpov Andrey , Verhoeven Aswin , Jansen Martin 
Published: August 2005

AbstractLi7MO6 (M = Bi, Ru, Os) have been synthesized by solid state reaction of Li2O with Bi2O3, or MO2 (M = Ru, Os) and characterized using powder X‐ray diffraction, differential scanning calorimetry, magnetic susceptibility (for M = Ru, Os), ionic conductivity and 6Li solid state NMR (for M = Bi) measurements. All three compounds exhibit a temperature induced triclinic – rhombohedral phase transition. Structures of the new low temperature triclinic phases have been refined by the Rietveld method from powder X‐ray data using atomic parameters of Li7TaO6 as a starting model (Li7BiO6: triclinic, $P{\bar 1}$, a = 5.5071(1), b = 6.0425(1), c = 5.5231(1) Å, α = 116.912(1), β = 120.867(1), γ = 62.234(1)°, V = 133.96(1) Å3, Z = 1, T = 230 K; Li7RuO6: triclinic, $P{\bar 1}$, a = 5.3654(1), b = 5.8584(1), c = 5.3496(1) Å, α = 117.182(1), β = 119.117(1), γ = 62.632(1)°, V = 124.43(1) Å3, Z = 1, T = 295 K; Li7OsO6: triclinic, $P{\bar 1}$, a = 5.3786(1), b = 5.8725(1), c = 5.3591(1) Å, α = 117.193(1), β = 119.277(1), γ = 62.700(1)°, V = 125.15(1) Å3, Z = 1, T = 295 K). Upon cooling, Li7RuO6 and Li7OsO6 undergo a magnetic transition at 12 and 13 K, respectively, from the paramagnetic to the antiferromagnetic state. The higher ionic conductivity of Li7BiO6 at T < 300 °C, as compared to Li7RuO6 and Li7OsO6, can be ascribed to the undergoing of the triclinic – rhombohedral transition at a much lower temperature. At T > 300 °C, the ionic conductivity of all three compounds increases sharply due to the melting of the lithium sublattice; for Li7RuO6 and Li7OsO6 the latter effect is superimposed by the phase transitions to the rhombohedral modifications.
Anhydrous CuC4O4, a Channel Structure solved from X–ray Powder Diffraction Data
Authors: Dinnebier Robert E. , Nuss Hanne , Jansen Martin 
Published: August 2005

AbstractThe crystal structure of the new anhydrous metal squarate CuC4O4 was solved from laboratory X–ray powder diffraction data. It crystallizes in the monoclinic space group I2/a (no. 15) with the lattice parameters a = 5.6747(1), b = 8.9394(4), c = 9.4987(4) Å und β = 94.372(2)° at ambient conditions (Z = 4, RF2 = 8.24 %). The crystal structure can be reduced to a defect variant of the AlB2 type of structure ([C4O4][Cu □] ⇔︁ [Al][B2]) and shows channels parallel to the a axis with a free diameter of about 2.3Å. The squarate dianion, [C4O4]2−, is acting as a μ6–ligand, in this case.
Chemischer Transport fester Lösungen. 23 [1] Der Chemische Transport von Mischphasen im System MoS2/MoSe2, MoS2/NbS2, MoSe2/NbSe2 und NbS2/NbSe2
Authors: Hotje U. , Binnewies M. 
Published: August 2005

AbstractChemical Vapor Transport of Solid Solutions. 23 Chemical Vapor Transport of Mixed Phases in the System MoS2/MoSe2, MoS2/NbS2, MoSe2/NbSe2 and NbS2/NbSe2X‐ray powder investigations have shown that MoS2/MoSe2, MoS2/NbS2, MoSe2/NbSe2 and NbS2/NbSe2 form mixed crystals without a miscibility gap. The mixed crystals can be prepared by heating the Elements for some days in the presence of small amounts of iodine as well as by chemical vapour transport. In the systems NbS2/NbSe2 and MoS2/MoSe2 the vapor transport occurs congruently, in the systems NbS2/MoS2 and NbSe2/MoSe2 however a strong enrichment of Niobium has been observed during the transport process. Mass spectrometric investigations and thermochemical calculations have shown that the transport occurs via NbI4(g) and MoI3(g).
Chemischer Transport fester Lösungen. 22 [1] Beschreibung des Chemischen Transports im System ZnS/ZnSe
Authors: Hotje U. , Rose C. , Binnewies M. 
Published: August 2005

AbstractStudies on the Chemical Vapor Transport in the System ZnS/ZnSeBy means of chemical transport reactions homogeneous ionic mixed crystals with well defined compositions can be prepared in a simple way. This is shown at the example of ZnS/ZnSe‐mixed crystals. ZnS1−xSex‐mixed crystals can be prepared by chemical vapour transport in the temperature gradient 1000 → 900 °C using iodine as transport agent. A thermodynamic model is presented to calculate the thermodynamic stability of ionic mixed phases and possible enrichment effects during the vapor transport. The results are compared with experimental fundings and well known transport models.
Two Hydrogen‐bonded Supramolecular Frameworks of the 4,4′‐Diazido‐2,2′‐stilbene Disulfonate Anion
Authors: Wang Yanqin , Cao Rong , Bi Wenhua , Li Xing , Li Xiaoju , Wang Yuling 
Published: August 2005

AbstractTwo novel supramolecular frameworks, [Co(en)3](dasb)(ClO4)·H2O (1) and [Ni(en)2(H2O)2](dasb) (2), constructed by 4,4′‐diazido‐2,2′‐stilbenedisulfonate anion (dasb)2− through weak interactions, have been synthesized and characterized by single crystal X‐ray diffraction. As expected, in the two structures sulfonate groups of the anion form strong hydrogen bonds with the coordinated en and water molecules as H‐bond acceptor and the components were connected by the hydrogen bonds into 3D networks.
A New Complex of Europium(II) with edta – Structure and Spectroscopy
Authors: Janicki Rafał , Mondry Anna , Starynowicz Przemysław 
Published: August 2005

AbstractA new complex of europium(II) with ethylenediaminetetraacetic acid was obtained by electrochemical reduction. The compound is composed of polymeric $\rm [Eu(edta)]_{\infty}^{\phantom{\infty}2\infty-}$ chains, guanidinium cations and water molecules. The Eu2+ cation is eight‐coordinate (two nitrogen atoms and six carboxylate oxygen atoms), and contrary to europium(III) complexes with edta, does not contain water molecules in the first coordination sphere. Relationships between the coordination mode and IR as well as UV–Vis spectra are discussed.
Reactive E=C(p‐p)π‐Systems. 56 [1] Attempted Preparation of PhE=C(CF3)2 by Reactions of Hexafluoroacetone with PhE(SiMe3)2 (E = As, P)
Authors: Albers Thomas , Grobe Joseph 
Published: August 2005

AbstractThe chance to prepare sterically and inductively stabilized arsa‐ and phosphaalkenes of the type PhE=C(CF3)2 (E = As, P) by reacting phenyl‐bis(trimethylsilyl)‐arsane (1) and ‐phosphane (5), respectively, with hexafluoroacetone (HFA) was investigated. The insertion of the carbonyl function in one of the Si–E bonds was found to occur at temperatures between −78 and 20 °C. The elimination of hexamethyldisiloxane, which in case of acylamides and ketones spontaneously follows the insertion and in case of RE(SiMe3)–CR′2(OSiMe3) at least can be initiated by solid sodium hydroxide as catalyst, turned out to be impossible for the primary products PhE(SiMe3)–C(CF3)2‐OSiMe3 [E = As (2), P (6)]. 2 and 6 were characterized by analytical (C, H) and spectroscopic methods (IR, NMR, MS).
Condensation Reaction of Dimethyltin(IV) Oxide with 2‐(2,3‐Dichloroanilino)benzoic Acid Synthesis and Study of a Novel Dimeric Tetraorganodistannoxane
Authors: Kovala‐Demertzi Dimitra , Dokorou Vaso , Kruszynski Rafal , Wiecek Joanna , Bartczak Tadeusz J. , Demertzis Mavroudis A. 
Published: August 2005

AbstractThe novel symmetric dimeric tetraorganodistannoxane [(Me2Sn)4(DCPA)2)O2(OH)2] (2) and [(Me2Sn)4(DCPA)2)O2(OC2H5)2] (3) where HDCPA is 2‐(2,3‐dichloroanilino)benzoic acid (1) have been prepared. The crystal structure of 3 has been determined by X‐ray crystallography. Three distannoxane rings are present to the centrosymmetric dimeric tetraorganodistannoxane by virtue of μ3‐oxo form the central R4Sn2O2 core with a planar Sn2O2 ring, resulting in a ladder type structural motif. Five‐coordinated tin atoms are present in the distannoxane dimer. The ligands act as monodentate agents, thus rendering the tin atom five‐coordinated. Significant π → π stacking interactions and intramolecular hydrogen bonds stabilize the structure 3. The polar imino hydrogen atom participates in intramolecular hydrogen bonds.The formation of the dimeric distannoxanes 2 and 3 represent a ladder‐type carboxylates in which the insertion of a μ2‐OH or a μ2‐OC2H5 group occurs. This unusual result can be interpreted in terms of a competition between the strength different donors, in which the –OH or the –OC2H5 groups show higher donor capacity than the carboxylato group of DCPA.