bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mammalian alkaloids: Synthesis and O‐methylation of (S)‐ and (R)‐3′‐hydroxycoclaurine and their N‐methylated analogues with S‐adenosyl‐L‐[methyl‐14C]methionine in presence of mammalian catechol O‐methyltransferase
Authors: He Xiao‐Shu , Tadić Dragana , Brzostowska Malgorzata , Brossi Arnold , Bell Maureen , Creveling Cyrus 
Published: December 2004

AbstractO‐Methylation of the optically active 3′‐hydroxycoclaurines 3a and 3b and of the N‐methylated analogs 5a,b with S‐adenosyl‐L‐[methyl‐14C]methionine in presence of mammalian COMT was investigated in vitro. The N‐unsubstituted (1S)‐ and (1R )‐isomers 3a and 3b, respectively, afforded almost equal amounts of the corresponding N‐norreticuline 4 and N‐nororientaline 19, besides two unknown by‐products (see Fig. and Table 1). The N‐methylated (1S)‐isoquinoline 5a, on the other hand, afforded largely (S)‐orientaline ((S)‐19), while an almost equal mixture of (R)‐reticuline (6b) and (R)‐orientaline ((R)‐19) was obtained from the (1R)‐enantiomer 5b. The isoquinolines 3a,b and 5a,b were prepared by a Bischler‐Napieralski cyclization yielding O‐benzyl‐protected isoquinoline 10 (Scheme 1). The optical resolution of 10 was accomplished with 2′‐bromotartranilic acid. The N‐methylated isoquinolines were prepared by N‐formylation of 10a,b and reduction of the formamides 13a,b with diborane (→ 14a,b). Deblocking of the benzyl‐ether moieties of 10a,b and 14a,b was accomplished by catalytic hydrogenation in presence of HCl, affording directly 3a,b·HCl and 5a,b·HCl, respectively.
Der ‘Push‐Pull’‐Effekt von ‘Push‐Pull’‐Oligoacetylenen. Eine 13C‐NMR‐Untersuchung
Authors: Neuenschwander Markus , Bartlome Andreas 
Published: December 2004

The ‘Push‐Poll’ Effect of ‘Push‐Pull’ Oligoacetylenes. A 13C‐NMR InvestigationAccording to 13C‐chemicaI shifts of ‘push‐pull’ oligoacetylenes 1–4, the ‘push‐pull’ effect (i.e. π delocalization induced by ‘push‐pull’ substituents) rapidly decays in this series. To correct for other than π ‐charge‐density effects, Δδ values of symmetrically placed C‐atoms of the oligoacetylene chain are discussed. Stereoelectronic resteffects (SER) of the substituents on terminal C‐atoms of PP‐ketones 1a–3a and PP‐esters 1b–4b are estimated from the residual Δδ of the asymptotes of Fig. 3. Fig. 4 convincingly shows that Δδ values are dramatically decreasing with increasing number n of acetylene units between the push and pull substituents. Assignment problems of ‘push‐pull’ triacetylenes 3 have been solved by 13C labelling of the CO group of 3a.
Approaches to the synthesis of cytochalasans. Part 10. Cuprates as reagents for the formation of CC bonds
Authors: Matthes Michael , Tamm Christoph 
Published: December 2004

AbstractBased upon our novel concept for the total synthesis of cytochalasans, the model lactams 2–9 were treated with Bu2Cu(CN)Li2. The results of these conversions vary much from those obtained with Ph2Cu(CN)Li2, demonstrating the uncertainty of predictions in cuprate chemistry. The bicyclic compound 20 was prepared in good yield. However, all attempts to convert p‐toluenesulfonate 20 into the Ph‐substituted derivative 21, an intermediate for the synthesis of cyiochulusm B(1), have failed so far.
Crystal Structure and ESR Study of a Bimetallic Copper/Iron Crown Ether Inclusion Complex
Authors: Chetcuti Peter A. , Liégard André , Rihs Grety , Rist Günther , Schweiger Arthur 
Published: December 2004

AbstractBimetallic inclusion complexes have been synthesized by a secondary coordination interaction between the guest complex [Fe(η5‐C5H5)(CO)2(NH3)][PF6] and copper(II) complex 1a or nickel(II) complex lb containing crown‐ether hosts. The X‐ray crystal‐structure analysis established that the Cu,Fe inclusion complex 2 crystallize as a centrosymmetric dimer with a CuCu separation of 3.73 Å and a novel out‐of‐plane CuN interaction. The magnetic parameters for 2 were obtained by ESR and ENDOR spectroscopy. ESR susceptibility measurements down to 6 K exclude the presence of any antiferromagnetic coupling interaction between the CuIIcenters of the dimer.
Heterocyclen aus Bis(alkoxycarbonyl)keten‐ethylen‐acetalen ( = Dialkyl‐2‐(1,3‐dioxolan‐2‐yliden)propan‐1,3‐dioate). Synthese und Eigenschaften einer neuen Klasse von Pyrazolium‐Betainen
Authors: Neidlein Richard , Schröder Günter , Krieger Claus , Kikelj Danijel 
Published: December 2004

Heterocycles Starting from Bis(alkoxycarbonyl)ketene Ethylene Acetals ( = Dialkyl 2‐(1,3‐Dioxolan‐2‐ylidene)propane‐1,3‐dioate). Synthesis and Properties of a New Class of Pyrazolium BetainesThe readily available bis(alkoxycarbonyl)ketene ethylene acetals 1 react with bifunctional nucleophiles to give heterocycles 2–5 (Scheme 1). Their reactions with N,N‐dialkylhydrazines lead to the pyrazolium betaines 7a–f (Scheme 4). Cyclic N,N‐dialkylhydrazines give spiro compounds 7d–f. The reaction of thioketene acetal 12 and of the derivative 15 of methanetricarboxylic acid with N,N‐dimethylhydrazine results in the formation of 3‐(methylthio)‐ and 3‐methoxypyrazolium betaine 7g and 7h, respectively (Scheme 4). The chemical reactivity of the synthesized pyrazolium betaines 7 was tested. The structure of the 3‐(methylthio) derivative 7g was determined by X‐ray analysis.
The Diels‐Alder Chemoselectivity of 3,4,6,7‐Tetramethylidenebicyclo[3.2.1]octane‐2‐exo, 8‐syn‐diyl Derivatives
Authors: Claret François , Razaname Alain , Vogel Pierre 
Published: December 2004

AbstractStrong dienophiles prefer to add onto the diene moiety attached at C(2),C(3) of 2,3,6,7‐tetramethylidenebicyclo[3.2.1]octane ((±)‐1; see Scheme 1), whereas in the case of 3,4,6,7‐tetramethylidenebicyclo[3.2.1]octane‐2‐exo,8‐syn‐diyl derivatives, the diene moiety at C(6),C(7) reacts faster than that at C(3),C(4), as long the bulk of the 8‐syn‐substituent is large enough (see Schemes 2 and 3).
Photolytic Reactions of (o‐Allylbenzyl)dicarbonyl(η5‐cyclopentadienyl)iron
Authors: Thoma Gebhard , Giese Bernd 
Published: December 2004

AbstractPhotolysis of (o‐allylbenzyl)dicarbonyl(η5‐cyclopentadienyl)iron (4) at 20° in CH2Cl2 leads to carbon‐monoxide loss followed by intramolecular complexation to [η2‐(o‐allylbenzyl)]carbonyl(η5‐cyclopentadienyl)iron (13). At 50° in C6D6, a photochemical rearrangement proceeds forming carbonyl (η5‐cyclopentadienyl){η3‐[3‐(2‐methylphenyl)allyl]}iron (17). Depending on the temperature, photolysis of 4 leads to intermolecular reactions at the benzylic or allylic position of the π complexes 13 and 17, respectively.
Confromational Studies on Peptides Containing Enantiometric α‐Methyl α‐Amino Acids. Part I. Differential conformational properties of (R)‐ and (S)‐2‐methylaspartic acid
Authors: Altmann Karl‐Heinz , Altmann Eva , Mutter Manfred 
Published: December 2004

AbstractThe conformational properties of four model peptides of the general formula Ac‐Tyr‐Xaa‐Yaa‐Zaa‐Ala‐Lys‐Glu‐ala‐Ala‐Glu‐Lys‐Ala‐Zaa‐Yaa‐Xaa‐Lys‐NH2 (Xaa‐Yaa‐Zaa = Ala‐Ala‐(R)‐Asp(2‐Me), 1; Ala‐Ala‐(S)‐Asp(2‐Me), 2; Ala‐Aib‐Asp, 3; Ala‐Ala‐Asp, 4; Asp(2‐Me) = 2‐methylaspartic acid; Aib = 2‐aminoisobutyric acid) were studied by CD spectroscopy in solution, to evaluate the helix‐inducing potential of enantiomerically pure 2‐methylaspartic acid as a function of its chirality at C(2). At neutral pH and 1°, all peptides exhibit significant helix formation in aqueous solution, the degree of helicity increasing in the order 4 3 ≈ 1. Lowering the pH to 2 results in a dramatic increase in helicity for peptide 1, while the diastereoisomeric peptide 2 now exists in a predominantly unordered conformation. Helix induction by protonated (R)‐Asp(2‐Me) exceeds Aib‐induced helix formation in peptide 3, and the helix content of 1 in aqueous solution at pH 2 is comparable to the degree of helicity in the strongly helix‐inducing solvent 2,2,2‐trifluoroethanol.
Ring‐Transformation von Imidazolidin–2,4‐dionen ( = Hydantoinen) zu 4H‐Imidazolen bei der Umsetzung mit 3‐(Dimethylamino)‐2,2‐dimethyl‐2H ‐azirin
Authors: Schläpfer‐Dähler Marlise , Mukherjee‐Müller Gabriele , Heimgartner Heinz 
Published: December 2004

Ring Transformation of Imidazolidine‐2,4‐diones ( = Hydantoins) to 4H‐Imidazoles in the Reaction with 3‐(Dimethylamino)‐2,2‐dimethyl‐2H‐azirinesAt ca. 70°, 3‐(dimethylamino)‐2,2‐dimethyl‐2H ‐azirine (1) and 5,5‐disubstituted hydantoins 4 in MeCN or i‐PrOH give 2‐(1‐aminoalkyl)‐5‐(dimethylamino)‐4,4‐dimethyl‐4H ‐imidazoles 5 in good yield (Scheme 2). These products are decarboxylated 1:1 adducts of 1 and 4. A reaction mechanism is suggested in analogy to the previously reported reactions of 1 and NH‐acidic heterocycles containing the CONHCONH moiety (Scheme 5). The formation of ureas 6 and 7 can be rationalized by trapping the intermediate isocyanate F by an amine. No reaction is observed between 1 and 1,5,5‐ or 3,5,5‐trisubstituted hydantoins in refluxing MeCN or i‐PrOH, but an N‐isopropylation of 1,5,5‐trimethylhydantoin (8b) occurs in the presence of morpholine (Scheme 3). The reaction of the bis(azirine)dibromozink complex 11 and hydantoines 4 in refluxing MeCN yields zink complexes 12 of the corresponding 2‐(1‐aminoalkyl)‐4H ‐imidazoles 5 (Scheme 4).
Synthesis and X‐Ray Structural Studies of ‘4,7,13‐Trioxa‐1,10‐diaza‐5,6‐benzocyclopentadecane‐2,9‐dione’ ( = 5,6,9,10‐Tetrahydro‐2H, 8H‐benzo[b][1,4,10]trioxa[7,13]diazacyclopentadecene‐311(4H,12H)‐dione) and ‘4,7,13,16‐Tetraoxa‐1,10‐diaza‐5,6‐benzocyclooctadecane‐2,9‐dione’ ( = 5,6,8,9,12,13‐Hexahydro‐2H,11H‐benzo[b][1,4,10,13]tetraoxa‐ [7,16]diazacyclooctadecene‐3,14(4H, 15H)‐dione)
Authors: Gluziński Przemyslaw , Jurczak Janusz , Krajewski Janusz W. , Sałański Piotr , Stankiewicz Tomasz , Urbańczyk‐Lipkowska Zofia , Armbruster Thomas , Bürgi Hans‐Beat 
Published: December 2004

AbstractThe molecular structures of the title compounds 3 and 5 were investigated by NMR and X‐ray structural methods. The NMR results suggest two equivalent halves for both molecules. The X‐ray study shows an approximate mirror plane for 3 and an approximate twofold axis for a significant portion of the macrocycle of 5.
1,3,5‐Triamino‐1,3,5‐trideoxy‐cis‐inositol, a New Ligand with a Remarkable Versatility for Metal Ions. Part 2. Safe and efficient ligand preparation and structure of the free ligand and the CoIII complex
Authors: Ghisletta Michele , Hegetschweiler Kaspar , Jalett Hans‐Peter , Gerfin Tobias , Gramlich Volker 
Published: December 2004

AbstractA new, convenient, and safe route to 1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol (taci) was investigated by hydrogenation of azo‐coupled derivatives of phloroglucinol. In the presence of acetic anhydride, the reduction of trisphenylazophloroglucinol (H2/Pd(5%) on C) resulted in the formation of tri‐, hexa‐, and nona‐acetylated derivatives of triaminophloroglucinol. All three compounds are air‐stable, colorless solids. However, the succeeding hydrogenation to the cyclohexane derivative failed. Trisodiumtris(p‐sulfonatophenylazo)phloroglucinol could be hydrogenated in a one‐pot reaction to the desired taci· 1.5H2SO4 using a Pt/Rh oxide as catalyst. taci provides two distinct chair conformations with either three amino or three hydroxy groups for metal binding. The unique metal‐binding properties are discussed in terms of minimal conformational changes required for coordination. Conformational analysis, based on X‐ray structural data of [BiCl6][H3(taci)] ·2 H2O (Pnma, a = 24.314 (5) Å, b = 10.215 (2) Å, c = 7.422 (8) Å, R = 5.8%) and [Co(taci)2(NO3)3]·2H2O (C2/c, a = 22.912 (8) Å, b = 8.942 (2) Å, c = 14.731 (3) Å, β = 128.66 (2)°, R = 4.9%) and the previously investigated [Cr(taci)2]3+ revealed an almost ideal chair conformation in all three molecules.
Protonic Quantum Correlations in the H‐Bond Dynamics of Nucleic Acids. Part 1. Conformational comparison of G‐C with Benner's κ‐π
Authors: Chatzidimitriou‐Dreismann C. Aris 
Published: December 2004

AbstractA new base pair (called κ‐π) of Watson‐Crick type, with an H‐bond pattern different from that in A‐T and G‐C base pairs, has been recently synthesized by Benner and coworkers and shown to be stable and incorporable into duplex DNA and RNA by polymerases. This new base pair, which contains three H‐bonds, is compared with G‐C, in the framework of modern dynamical theory of quantum nonlocality and quantum correlations (also called Einstein‐Podolsky‐Rosen correlations). Connection with the traditional treatment of proton transfer in DNA base pairs, which uses the adiabatic approximation (thus considering the protons as classical particles), is explicitly made. As a result, the dynamics of the H‐bond pattern of G‐C is shown to exhibit a specific quantum‐mechanical phase stability (or: rigidity, stiffness), which is clearly missing in the case of κ‐π. This finding is discussed and illustrated, also in connection with recent quantum chemical calculations of proton transfers in DNA base pairs. Additionally, certain speculations concerning a probable ‘evolutionary advantage’ of G‐C with respect to κ‐π are shortly considered.
Paramagnetic Redox Stages of a Bisphane: An ESR and ENDOR Study
Authors: Gerson Fabian , Scholz Markus , De Meijere Armin , König Burkhard , Heinze Jürgen , Meerholz Klaus 
Published: December 2004

AbstractSeven redox stages, the dication 12+, the radical cation \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {{+}\kern-4pt {.}\kern-2pt }}$\end{document}, the neutral 1, the radical anion \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {{\relbar}\kern-4pt {.}\kern-2pt }}$\end{document}, the dianion 12−, the radical trianion \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {3{\relbar}\kern-4pt {.}\kern-2pt }}$\end{document}\end{document}, and the tetraanion 14−, are indicated by cyclic voltammetry for the bisphane 1, in which the benzene decks of two lateral paracyclophane moieties are orthogonal to the plane of anthracene framework. In \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {{+}\kern-4pt {.}\kern-2pt }}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {{\relbar}\kern-4pt {.}\kern-2pt }}$\end{document}, the unpaired electron is accommodated into the central anthracene subsystem, and the same statement holds for the two positive or negative charges in 12+ and 12−. Formation of \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {3{\relbar}\kern-4pt {.}\kern-2pt }}$\end{document}\end{document} and 1− occurs through admission of additional electrons one‐by‐one into the two paracyclophane moieties flanking the doubly charged anthracene subsystem in 12−. The above‐postulated, successive release or uptake of electrons by the individual parts of the bisphane is in perfect accord with the hyperfine data determined by ESR and ENDOR spectroscopy for \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {{+}\kern-4pt {.}\kern-2pt }}$\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {{\relbar}\kern-4pt {.}\kern-2pt }}$\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$1^{\scriptstyle {3{\relbar}\kern-4pt {.}\kern-2pt }}$\end{document}\end{document}, as well as for radical ions of suitable reference compounds.
Reactions of Carbonyl Group with Nitroso Compounds: Reaction of Formaldehyde with Substituted Nitrosobenzenes
Authors: Uršić Stanko 
Published: December 2004

AbstractFormaldehyde reacts with substituted nitrosobenzenes giving the corresponding N‐phenylhydroxamic acids. A mechanism involving three sequential steps in this reaction is proposed. The first step is the nucleophilic attack of the nitroso group on the carbonyl group which leads to the formation of the unstable tetrahedral zwitterionic intermediate. This step is followed by the proton transfer to the zwitterionic intermediate to form more stable nitrosocarbinolic cation intermediate, which in the subsequent step undergoes the rate‐controlling elimination of proton from the C‐atom of nitrosocarbinolic group, leading to the final product, hydroxamic acid. The first and the second step appear to be reversible. The experimental evidence obtained, which is the basis for such a description of the investigated reaction, includes: (a) the order of reactivity of substituted nitrosobenzenes, as demonstrated by the plot of log kobs vs. σ Hammett parameters with slope of −1.74; (b) the observation of a general‐acid catalysis; (c) the observation of the inverse solvent deuterium isotope effect of ca. 1.8 in the reaction; (d) the observation of kinetic primary deuterium isotope effect of ca. 8 related to the ‘water’ reaction in the reactions of formaldehyde with substituted nitrosobenzenes; (e) the observation of general‐base catalysis in the reaction; (f) the observation of the kinetic primary deuterium isotope effect of ca. 2.1 for the acetate‐ion‐catalyzed reaction.
(o‐Hydroxyphenyl)methylphosphonic acids: Synthesis and potentiometric determinations of their pKa Values
Authors: Böhmer Volker , Vogt Walter , Chafaa Salah , Meullemeestre Jean , Schwing Marie‐José , Vierling François 
Published: December 2004

Abstract(o‐Hydroxyphenyl)methylphosphonic acids are readily obtained from o‐(bromomethyl)‐ or o‐(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pKa values have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric effects.
Enantioselective Synthesis of α‐N‐Alkylamino Acids via Sultam‐Directed ‘Enolate’ Hydroxyamination
Authors: Oppolzer Wolfgang , Cintas‐Moreno Pedro , Tamura Osamu , Cardinaux Francis 
Published: December 2004

AbstractCrystalline N‐hydroxyamino‐acid derivatives 4, readily available from non‐chiral acyl chlorides 2 and sultams 1, were treated with aldehydes in the presence of NaBH3CN to give N‐alkylhydroxylamines 5. N,O‐Hydrogenolysis of 5 and saponification of 6 furnished (S)‐N‐alkylamino acids 7 in high optical purity. Similarly, (R)‐N‐alkylamino acids 12 were obtained from the antipodal acylsultams 8.
Warum pentose‐und nicht hexose‐nucleinsäuren? Teil III. Oligo(2′,3′‐dideoxy‐β‐D‐glucopyranosyl) nucleotide (‘homo‐DNS’): Paarungesigenschaften
Authors: Hunziker Jürg , Roth Hans‐Jorg , Böhringer Markus , Giger Alfred , Diederichsen Ulf , Göbel Michael , Krishnan Ravichandran , Jaun Bernhard , Leumann Christian , Eschenmoser Albert 
Published: December 2004

Why Pentose‐And Not Hexose‐Nucleic Acids? Part III. Oligo(2′,3′‐dideoxy‐β‐D‐glucopyranosyl)nucleotides. (‘Homo‐DNA’): Base‐Pairing PropertiesSummary in collaboration with Prof. Dr. C. E. Wintner, Haverford College, Haverford, PA 19041‐1392.
The paper presents results of a comprehensive investigation on the pairing properties of homo‐DNA oligonucleotides, the preparation of which has been described in Part II of this series [2]. The investigation was carried out by using established methods described in the literature for the characterization of oligonucleotides in the natural series, such as determination of melting temperatures of oligonucleotide duplexes by temperature‐dependent of melting temperatures, determination of pairing stoichiometry by ratio‐dependent UV spectroscopy of binary mixtures of pairing partners, temperature‐dependent CD spectroscopy, gel electrophoresis under non‐denaturing conditions, and – in selected cases – 1H – and31P‐NMR spectroscopy.The systematic comparison of the paring properties of homo‐DNA oligonucleotides with corresponding DNA nucleotides (up to dodecamers) indicates that homo‐DNA is a highly efficient, autonomous, artificial pairing system with a pairing behavior that is in part similar to, but also, in part, strikingly different from, the pairing behavior of DNA. The pairing properties established so far are listed below in a manner that reflects the sequence of subtitles in Chapt.2 of the text; they were determined under the conditions: H2O, 0.15M NaCl, 0.01M Tris‐HCl buffer, pH 7, oligonucleotide concentrations in the μM range, 1:1 ratio of single strands in the case of non‐selfcompementary sequences.
Transport Properties of H+‐Selective Membranes Containing Amine‐Derivative Ionophores and Mobile Sites
Authors: Nahir Tal M. , Buck Richard P. 
Published: December 2004

AbstractTransport processes in plasticized PVC membranes containing the H+ chromoionophore ETH 5294 and additional tetraphenylborate‐type mobile sites were analyzed by employing the potential‐step method. Using chronoamperometry, impedance spectroscopy, and UV/VIS absorbance measurements, it is shown that the ionophore behaves as a carrier for protons, when the membranes are immersed between two aqueous solutions. It was possible to document the changes in the concentration profiles of both free ionophores and ionic species in some of the membranes. There is no evidence of proton hopping between the ionophores.
Zine Complexes of Cysteine, Histidine, and Derivatives Thereof: Potentiometric determination of their compositions and stabilities
Authors: Gockel Peter , Vahrenkamp Heinrich , Zuberbühler Andreas D. 
Published: December 2004

AbstractThe stabilities of Zn complexes of cysteine and histidine have been determined together with those with those of three derivatives of each n which one of their three donor functions (carboxyl, amino, and mercapto and imidazole, respectively) has been blocked. Using potentionmetric titrations of aqueous solutions, the 1:1 and 1:2 complexes of all for cysteine‐ and all four histidine‐derived ligands are observed among te various species present (ligands, 1:1 and 1:2 complexes, and protonatd derivatives thereof). All cysteine‐derived complexes are more stable than the corresponding histidine‐derived complexes by 1–2 orders of magnitude for the 1:1 composition and by 1–6 order of magnitude for the 1:2 composition. For the cysteine series, the sequence of stabilities is cysteine > cysteine ethyl ester ≫ N(α)‐acetylcysteine ≫ SMethylcysteine. For the histidine series, the corresponding sequence is histidine > histidine methyl ester > N,N (imidazole)‐dimethylhistidine > N(α)‐acetylhistidine. The order of stabilities can be explained by the relative strengths of the Zn–S vs. Zn–N coordination, y charge effects, and by chelate ring sizes.
Metal Complexes with Macrocylclic Ligands. Part XXXV. Stabilities of some bivalent metal‐ion complexes with 1,4,7‐triazacyclononane‐1‐acetie acid
Authors: Cai Hui‐Zhi , Kaden Thomas A. 
Published: December 2004

AbstractThe stability constants of the Mn2+, Zn2+, Ni2+, pb2+, and Cd2+ complexes with 1,4,7‐triazacylononane‐1‐acetic acid (noma) were determined at 25° and 0.5M (KNO3) by potentiometric titrations. The species [ML] and [ML(OH)] were found in al cases except for Ni2+, whereas [ML2] was only detected for Cd2+. For the complexes [ML], the order of stability is Mn2+ < Cd2+ < pb2+ < Zn2+ < Zn2+ < Ni2+ < Cu 2+, which is consisten with the Irvin‐Williams Series.
1,1′‐Disubstituted Ferrocene‐Containing Thermotropic Liquid Crystals of structure [Fe{(η5‐C5H4)COOC6H4XC6H4OCnH2n+1}2] (X  OOC or COO). Influence of the orientation of the central ester function on the mesogenic properties
Authors: Deschenaux Robert , Marendaz Jean‐Lue , Santiago Julio 
Published: December 2004

AbstractThe two series I and II of 1,1′ ‐disubstituted ferrocenes which differ by the direction of the ester function included in the rigid organic part were synthesized and their liquid crystal properties examined. These latter were found to be strongly dependent on the orientation of the connecting ester group and on the alkyl chain length.