bluuebunny/crossref_metadata_2025_split huggingface dataset:
NIR Dyes Based on [M(R,R′timdt)2] Metal‐Dithiolenes: Additivity of M, R, and R′ Contributions To Tune the NIR Absorption (M = Ni, Pd, Pt; R,R′timdt = Monoreduced Form of Disubstituted Imidazolidine‐2,4,5‐trithione)
Authors: Aragoni M. Carla , Arca Massimiliano , Cassano Tiziana , Denotti Carla , Devillanova Francesco A. , Frau Romina , Isaia Francesco , Lelj Francesco , Lippolis Vito , Nitti Luigi , Romaniello Pina , Tommasi Raffaele , Verani Gaetano 
Published: May 2003

AbstractWith the aim of preparing new dyes for Q‐switching and/or mode‐locking Nd‐based lasers, such as Nd:YLF and Nd:YAG (emission wavelengths 1053 and 1064 nm, respectively), the syntheses of about 30 new neutral dithiolenemetal complexes belonging to the class [M(R,R′timdt)2] have been carried out [M = Ni (4a−c; 4g−j), Pd (5a−j), Pt (6a−j); R,R′timdt = monoreduced form of disubstituted imidazolidine‐2,4,5‐trithione]. The examination of the effects induced on the intense NIR absorption by changing M, R, and R′ has allowed for the recognition of the additive contributions (Δλ) of the central metal ion and of the substituents to the λM,R,R′max position of the NIR absorption maximum, which is in the region of 1000 nm. The high Δλ values due to aromatic substituents have been elucidated by means of Hybrid‐DFT calculations performed on the model compound [Ni(H2timdt)(Ph,H‐timdt)]. Both the λM,R,R′max values and the molar extinction coefficients vary with the solvent. Complex 5f [M = Pd, R = p‐F‐C6H4, R′ = m,m,p‐(MeO)3‐C6H2] shows that it has been possible to exactly match the emission wavelength of the Nd:YLF and Nd:YAG lasers in chloroform and toluene, respectively (by choosing the appropriate combination of metal ion and substituents). The highest extinction coefficient ever observed for a metal‐dithiolene (120000 M−1·cm−1 at 1034 nm in toluene) is also reported for complex 6g [M = Pt, R = p‐F‐C6H4, R′ = naphthyl]. Time‐resolved absorption dynamics measurements on 5f have also been carried out by means of pump‐probe experiments, with a picosecond Nd:YAG Q‐switched and mode‐locked laser. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Co‐Ligand Involvement in Ground and Excited States of Electron‐Rich (Polypyridyl)PtII Complexes
Authors: Klein Axel , Slageren Joris van , Záliš Stanislav 
Published: May 2003

AbstractThe electronic absorption and luminescence properties of electron‐rich organometallic platinum(II) complexes with aromatic α‐diimine ligands [(α‐diimine)PtR2] (R = alkyl, alkynyl, Ph or Mes, Mes = 2,4,6‐trimethylphenyl) were examined. The crystal and molecular structures of [(bpy)PtMe2], [(tap)PtPh2] and [(tmphen)PtMes2] were determined from single‐crystal XRD and discussed in view of intermolecular interactions that influence the emission behaviour. The combination of theoretical calculations (DFT) and spectroscopic techniques (absorption and emission) revealed the character of electronic transitions and excited states. In particular they showed that the co‐ligand involvement in the frontier orbitals is small for R = Me, but large in case of R = alkynyl, Ph or Mes. Depending on the chelate ligand and its substitution pattern, the emission efficiencies of the complexes cover a wide range from strong emission in fluid solution at ambient temperature to very weak emission in rigid matrices (glasses) at low temperatures with no emission at ambient temperature. The emission lifetimes, determined at low temperature in solvent glasses, mainly depend on the chelate ligand and not on the co‐ligands. The emission quantum yields of the complexes in solution at room temperatures are much larger for R = Mes than for R = Ph or Me. The emission bands for the complexes with unsaturated co‐ligands show slight structuring at low temperatures in contrast to the alkyl‐substituted ones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Exchange Interactions at the Supramolecular Level − Synthesis, Crystal Structure, Magnetic Properties, and EPR Spectra of [Mn(MAC)(TCNQ)2] (MAC = Pentaaza Macrocyclic Ligand; TCNQ·− = Radical Anion of 7,7,8,8‐Tetracyano‐p‐quinodimethane)
Authors: Madalan Augustin M. , Voronkova Violeta , Galeev Ravil , Korobchenko Ludmila , Magull Jörg , Roesky Herbert W. , Andruh Marius 
Published: May 2003

AbstractThe reaction between [Mn(MAC)(H2O)2]Cl2·4H2O and LiTCNQ (MAC = 2,13‐dimethyl‐3,6,9,12,18‐pentaazabicyclo[12.3.1]octadeca‐1(18),2,12,14,16‐pentaene) affords a complex with the formula [Mn(MAC)(TCNQ)2] (1), whose crystal structure has been determined. Its structure consists of neutral mononuclear entities. The manganese(II) ion is heptacoordinated, with a pentagonal bipyramidal geometry. The apical positions are occupied by the TCNQ·− radicals, while the macrocyclic ligand is coordinated at the equatorial positions. The seven Mn−N distances range from 2.273(3) to 2.301(6) Å. The strong intermolecular π−π stacking interactions between the TCNQ radicals (3.2 Å) leads to weave‐like infinite chains, which propagate along the crystallographic c axis. The cryomagnetic investigation of 1 revealed a weak intermolecular antiferromagnetic coupling of the Mn2+ ions (J = −0.18 cm−1), which is mediated by the diamagnetic (TCNQ)22− pairs resulting from the stacking interactions in the crystal. The intermolecular exchange interaction between the Mn2+ ions was further confirmed by variable temperature EPR spectroscopic measurements [|J| = 0.15(5) cm−1], which have been carried out in both the X and Q bands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
IR Study of the Interaction of Dioxygen with [meso‐Triphenyl(4‐pyridyl)porphyrinato]cobalt(II)
Authors: Kurtikyan Tigran S. , Ogden J. Steven , Kazaryan Robert K. , Madakyan Valery N. 
Published: May 2003

AbstractThe interaction of O2 (18O2) with [meso‐triphenyl(4‐pyridyl)porphyrinato]cobalt(II) [Co(MPyTPP)] has been investigated by means of IR spectroscopy under matrix‐isolation conditions and by the action of dioxygen on thin sublimed layers. These studies have led to the characterisation of two dioxygen adducts: (1) a very unstable dioxygen adduct similar to that observed earlier for the closely related [meso‐tetraphenylporphyrinato]cobalt(II) Co(TPP), and (2) a new type of coordinated O2 (18O2) complex which is formed after warming Co(MPyTPP) either in pure oxygen matrices, or as sublimed layers in the presence of oxygen. The ν(O2) vibration in this second species is more than 100 cm−1 lower than in the first, and the dioxygen adduct thus formed is thermally stable at 200 K. This adduct is identified as a six‐coordinate dioxygen complex, with one coordination site occupied by the pyridyl group of an adjacent Co(MPyTPP) molecule. In the sublimed layers, the capacity for self‐assembly of Co(MPyTPP) oligomers leads to the formation of microporous solids containing coordinatively unsaturated metal ions which have the ability to bind oxygen reversibly upon storage at ambient conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Characterisation and Antiamoebic Studies of Dioxovanadium(V) Complexes Containing ONS Donor Ligands Derived from S‐Benzyldithiocarbazate
Authors: Maurya Mannar R. , Khurana Shilpa , Shailendra  , Azam Amir , Zhang Wenjian , Rehder Dieter 
Published: May 2003

AbstractThree new dioxovanadium(V) compounds, [K(H2O)][VO2(sal‐sbdt)] (1), [K(H2O)2][VO2(Clsal‐sbdt)] (2), and [K(H2O)2][VO2(Brsal‐sbdt)] (3) (where H2sal‐sbdt are the Schiff bases formed between salicylaldehyde and dithiocarbazates) have been synthesised, and the structures of 1 and 2 revealed by X‐ray diffraction analyses. The ligands coordinate in the tridentate ONS fashion out of the enethiolate tautomeric form. The potassium counterions, coordinated to water molecules, the phenolate‐O, the oxo groups on vanadium and, in the case of 1, to the thiolate, provide interlinkages between the anions and thus a complex supramolecular network, further reinforced by intermolecular hydrogen bonds between oxo groups and water molecules. In vitro tests of the antiamoebic activity against the protozoan parasite Entamoeba histolytica showed comparable (1 and 2) or substantially better (3) amoebocidal action than metronidazole, a commonly used drug against amoebobiasis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
ZnII Complex with a Phenanthroline‐Containing Macrocycle as Receptor for Amino Acids and Dipeptides − Hydrolysis of an Activated Peptide Bond
Authors: Bazzicalupi Carla , Bencini Andrea , Berni Emanuela , Bianchi Antonio , Fornasari Patrizia , Giorgi Claudia , Valtancoli Barbara 
Published: May 2003

AbstractThe interaction between several L‐amino acids and dipeptides and the ZnII complex with ligand L, a macrocycle containing a triamine chain linking the 2,9 positions of a phenanthroline moiety, has been studied by means of potentiometric and 1H NMR spectroscopic measurements in aqueous solutions. In the [ZnL]2+ complex, the metal ion displays an unsaturated coordination environment and the metal can act as a binding site for these substrates. Amino acids and dipeptides in their neutral (zwitterionic) form bind to ZnII through the carboxylate function and, when in their anionic form, through the amine group. In this case the carbonyl of the amide function is probably also involved in metal coordination. Amino acids containing aromatic pendants form the most stable complexes, due to hydrophobic and/or π‐stacking interactions between the aromatic subunits of the substrates and the phenanthroline moiety of the metal receptor. The hydrolytic properties of the ZnII complex with L, involving the cleavage of the peptide bond, have been tested by using L‐leucine‐p‐nitroanilide (LNA), which contains an activated peptide bond. This substrate forms stable [ZnL(LNA)]2+ and [ZnL(OH)(LNA)]+ complexes. The formation of the [ZnL(OH)(LNA)]+ complex is followed by LNA hydrolysis, through a nucleophilic attack of the Zn−OH function on the peptide bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Quest for Isophosphaalkynes (Isophosphocyanides) C≡P−R — Still an Elusive Class of Compounds
Authors: Weber Lothar 
Published: May 2003

AbstractThis review gives an account on the quest for isophosphaalkynes, a class of compounds that still resists isolation and/or spectroscopic detection. Synthetic attempts toward this target are reported. On the other hand, a number of coordination compounds featuring isophosphaalkyne ligands have been prepared, the syntheses, structures, and chemistry of which are discussed.
Thermodynamics of Complex Formation of Silver(I), Cadmium(II) and Cobalt(II) with Open‐Chain Polyamines in Dimethyl Sulfoxide and Molecular Dioxygen Binding to Cobalt(II) Complexes
Authors: Comuzzi Clara , Melchior Andrea , Polese Pierluigi , Portanova Roberto , Tolazzi Marilena 
Published: May 2003

AbstractAgI, CdII and CoII complex formation with the primary and tertiary tetraamines 1,4,7,10‐tetraazadecane (trien) and 1,1,4,7,10,10‐hexamethyltriethylenetetraamine (hmtrien) has been studied at 298 K in the aprotic solvent dimethyl sulfoxide (DMSO) and in an ionic medium set to 0.1 mol·dm−3 with Et4NClO4 under anaerobic conditions. UV/Vis spectrophotometric and calorimetric measurements have been carried out to obtain the thermodynamic parameters for the systems investigated. Mononuclear 1:1 complexes are formed for all systems. In addition, trien also forms the ML2 mononuclear complex and a polynuclear M2L3 species with M = Cd2+ and Co2+. All the complexes are enthalpy stabilized, whereas the entropy changes counteract the complex formation. The results are discussed in terms of the different basicities, steric requirements and solvation both of the ligands and of the complexes formed. The influence of N‐alkylation on the selectivity of the ligands towards metal ions is analysed. In the case of the CoII complexes, their ability to take up dioxygen has also been studied by voltammetric and UV/Vis measurements and gasometric absorption. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Formation of Ruthenium−Aminocarbene Complexes from Aldimines and Aminals
Authors: Standfest‐Hauser Christina M. , Mereiter Kurt , Schmid Roland , Kirchner Karl 
Published: May 2003

AbstractSpecific pyridine‐based aldimines and aminals act as chelating ligands towards the RuCpL and RuTpL (Tp = hydrido trispyrazolylborate) fragments giving κ2N,N′‐coordinated cyclic imine complexes. Under particular conditions, as elucidated in this paper, these complexes rearrange into cyclic aminocarbene complexes. Thus, the reaction of [RuCp(L)(CH3CN)2]PF6 (L = CH3CN, PMe3, SbPh3) with 1 equiv. of py−N=CHR [R = Ph (phenyl), Fc (ferrocenyl), Np (naphthyl)] affords the cyclic aminocarbene complexes [RuCp(L)(=C(R)NH−py)]PF6, whereas when L = PPh3, PiPr3, and CO the reaction stops at the stage of the imine complex [RuCp(L)(κ2N,N′‐py−N=CHR)]PF6. Analogously, [RuTp(COD)Cl] (COD = 1,5‐cyclooctadiene) also reacts readily with the imines py−N=CHR (R = Ph, pMeOC6H4, Np) at elevated temperatures to yield the aminocarbene complexes [RuTp{=C(R)NH−py}Cl]. This process may open a new synthetic route for obtaining carbene complexes. The mechanism of the imine−aminocarbene conversion was analyzed by DFT/B3LYP calculations. Accordingly, the operation of a direct 1,2 hydrogen shift can be ruled out; the reaction seems to involve hydrido iminoacyl intermediates resulting from C−H bond activation and deprotonation/protonation steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structures and Thermodynamics of the Sulfuranes SF3CN and SF2(CN)2 as well as of the Persulfurane SF4(CN)2 − An ab initio MO Study by the G3(MP2) Method
Authors: Steudel Yana , Steudel Ralf 
Published: May 2003

AbstractAt the G3(MP2) level of theory the trans isomer 1a of the hypothetical molecule SF4(CN)2 is more stable than the cis isomer 1b by 8 kJ·mol−1. The isomerization of 1a to 1b requires an activation enthalpy of 319 kJ·mol−1 at 298 K. The decomposition of trans‐SF4(CN)2 to SF2(CN)2 and F2 is endothermic (ΔHo298 = 395 kJ·mol−1) but the elimination of FCN from trans‐SF4(CN)2 is exothermic by −7 kJ·mol−1. The elimination of (CN)2 from cis‐SF4(CN)2 is exothermic by −137 kJ·mol−1. The activation enthalpies for the latter two reactions were calculated as 251 and 311 kJ·mol−1, respectively. Thus, SF4(CN)2 should be a thermally stable compound. In the sulfuranes SF3CN and SF2(CN)2 the CN ligands prefer the equatorial positions; mutual exchange of an axial F atom by an equatorial CN group requires a reaction enthalpy of 51 kJ·mol−1 [SF3CN] or 58 kJ·mol−1 [SF2(CN)2]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cubane Complexes with Two (or More) Group 14−Group 16 Double Bonds: Synthesis and X‐ray Structures of Sn4Se2(NtBu)4 and Ge4Se3(NtBu)4
Authors: Chivers Tristram , Clark Timothy J. , Krahn Mark , Parvez Masood , Schatte Gabriele 
Published: May 2003

AbstractMonomeric complexes with two or three terminal M=Se bonds, Sn4Se2(NtBu)4 or Ge4Se3(NtBu)4, respectively, are produced by oxidation of (MNtBu)4 (M = Sn, Ge) with selenium in hot toluene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: IR Study of the Interaction of Dioxygen with [meso‐Triphenyl(4‐pyridyl)porphyrinato]cobalt(II) (Eur. J. Inorg. Chem. 10/2003)
Authors: Kurtikyan Tigran S. , Ogden J. Steven , Kazaryan Robert K. , Madakyan Valery N. 
Published: May 2003

AbstractThe cover picture shows a schematic view of part of a novel complex that undergoes reversible dioxygen binding. The complex is a zig‐zag oligomer formed in sublimed layers of [meso‐triphenyl(4‐pyridyl)porphyrinato]cobalt(II) and is depicted here with molecular dioxygen coordinated at each cobalt centre. The relatively open, microporous structure of the oligomer arises as a result of pyridine coordination, which inhibits closer‐packed structures (e.g. with parallel contiguous porphyrin rings), and ensures facile transport of molecular oxygen to the coordination site. The zig‐zag chain also inhibits the formation of dioxygen‐bridged centres, with the result that this basic structure is relatively stable. On warming, the Co−dioxygen link may be broken, with the evolution of dioxygen, which can readily diffuse through the microporous structure, leaving the zig‐zag oligomer chain effectively intact. Details are discussed in the article by T. S. Kurtikyan et al. on p. 1861 ff.
Amalgam Electrodes for Electroanalysis
Authors: Mikkelsen Øyvind , Schrøder Knut H. 
Published: May 2003

AbstractLiquid mercury is a unique material for the indicator electrode in voltammetry. One reason for this is the high overvoltage for hydrogen formation, thus extending the actual potential window. Diluted amalgams are important reaction products in voltammetric (polarographic) processes, however liquid amalgams are rarely used directly as electrode material for analytical purposes. Because of the fact that voltammetry is very suitable for field and remote monitoring, issues concerning the use of mercury electrodes in environmental analyses have led to considerable research effort aimed at finding alternative tools with acceptable performance. Solid electrodes are such alternatives. Different types of electrodes are reviewed. In particular, solid amalgam electrodes are very promising, with acceptable low toxicity to be used for field measurements. Solid amalgam electrodes are easy and cheap to construct and are stable over a reasonable time up to several weeks. Assessment of the toxicity risk and the long time stability for remote and unattended monitoring is discussed. The differences between solid dental amalgam electrodes, made by using techniques known from dental clinical practice, and mercury film or mercury layer electrodes on solid substrates are reviewed. In particular the dental technique for constructing solid amalgam electrodes gives advantage because it's fast and inexpensive. Also the technique for making dental amalgam has been explored and optimized over years by dentists, giving advantage when the same technique is used for constructing electrodes. Dental amalgam electrodes has been found to act similar to a silver electrodes, but with high overvoltage towards hydrogen. This make it possible to use the dental amalgam electrode for detection of zinc, cobalt and nickel in additions to other metals like lead, copper, thallium, cadmium, bismuth, iron etc. Also the use for reducible organic compounds is expected to be promising.
Reaction with N,N‐Diethyl‐p‐phenylenediamine: A Procedure for the Sensitive Square‐Wave Voltammetric Detection of Chlorine
Authors: Seymour E. Hugo , Lawrence Nathan S. , Compton Richard G. 
Published: May 2003

AbstractThe reaction of chlorine and N,N‐diethyl‐p‐phenylenediamine has been studied as a means of generating an analytical voltammetric signal of much improved sensitivity and selectivity for the detection of the former than is possible via direct electrolysis. A reaction mechanism is suggested whereby the chlorine attacks the primary amine of DEPD to form the N‐chlorinated product that shows a much enhanced signal under conditions of square‐wave voltammetry than does chlorine itself. The analytical parameters were found to vary with concentration of DEPD and a linear range from 17 to 495 μM was achievable with a corresponding limit of detection of 6.8 μM
Differential Pulse Techniques on Modified Conventional‐Size and Microelectrodes. Electroactivity of Poly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene] Coating Towards Dopamine and Ascorbic Acid Oxidation
Authors: Lupu S. , Parenti F. , Pigani L. , Seeber R. , Zanardi C. 
Published: May 2003

AbstractPoly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene] modified conventional‐size and (ultra)microelectrodes are first investigated in acetonitrile and quasi‐neutral aqueous solution with respect to the repeatability of the responses obtained both in cyclic voltammetry and in differential pulse voltammetry. The reactivity towards ferrocene and hydroquinone, chosen as benchmark oxidizable substances in the two media, respectively, is considered. Comparison is made with the behavior of poly(3‐methylthiophene) as electrode coating, which is one of the most commonly used redox mediators in amperometric sensors based on coatings consisting of conducting polymers. The results confirm the appealing properties of poly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene], previously evidenced by us in different electrochemical studies: it exhibits particularly high stability and the characteristics of the current/potential curves obtained make it particularly suitable for analytical purposes. After performing these tests, the quantitative determination of dopamine by modified microelectrode is examined and the simultaneous voltammetric determination of ascorbic acid and dopamine is considered. The possibility of working profitably with a microelectrode at very low buffer‐supporting electrolyte concentration is ascertained.
Capillary zone electrophoresis in methanol: Migration behavior and background electrolytes
Authors: Beckers Jozef L. , Ackermans Mariëtte T. , Boček Petr 
Published: May 2003

AbstractNonaqueous (NA) solutions are often used as background electrolytes (BGEs) and NA solvents are added to aqueous BGEs as organic modifiers in capillary zone electrophoresis (CZE), in order to optimize the separations. This can be tricky, however, because the pH* and pK* concepts may be totally different in NA solvents, whereas often less knowledge is available concerning phenomena, such as system zones, applying NA solvents. In this paper, the concepts of pH* and pK* are considered for methanol as a solvent and pK* values are determined for several components in mixtures of water and methanol. With a mathematical model, adapted for calculations in methanol, parameters are calculated describing the fronting or tailing character of peaks and the question of peaks or dips, and the existence of system zones is discussed for pure methanol as a solvent. These aspects are experimentally verified, applying BGEs useful for the separation of cationic species in the indirect UV mode. It can be concluded that the mathematical model developed for aqueous BGEs is applicable to BGEs in methanol, too, and that the behavior of BGEs in methanol is comparable with that in water concerning the fronting or tailing character of peaks and the question of peaks and dips, although the mobilities and pK values can change significantly.
Modeling the zeta potential of silica capillaries in relation to the background electrolyte composition
Authors: Berli Claudio L. A. , Piaggio María V. , Deiber Julio A. 
Published: May 2003

AbstractA theoretical relation between the zeta potential of silica capillaries and the composition of the background electrolyte (BGE) is presented in order to be used in capillary zone electrophoresis (CZE). This relation is derived on the basis of the Poisson‐Boltzmann equation and considering the equilibrium dissociation of silanol groups at the capillary wall as the mechanism of charge generation. The resulting model involves the relevant physicochemical parameters of the BGE‐capillary interface. Special attention is paid to the characterization of the BGE, which can be either salt or/and buffer solutions. The model is successfully applied to electroosmotic flow (EOF) experimental data of different aqueous solutions, covering a wide range of pH and ionic strength. Numerical predictions are also presented showing the capability of the model to quantify the EOF, the control of which is relevant to improve analyte separation performance in CZE.