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Apical Position (apical + position)

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Chemistry88%

Selected Abstracts

Ultrastructural study of spermiogenesis in the Jamaican Gray Anole, Anolis lineatopus (Reptilia: Polychrotidae)

ACTA ZOOLOGICA, Issue 4 2010
Justin L. Rheubert
Rheubert, J.L., Wilson, B.S., Wolf, K.W. and Gribbins, K.M. 2010. Ultrastructural study of spermiogenesis in the Jamaican Gray Anole, Anolis lineatopus (Reptilia: Polychrotidae). ,Acta Zoologica (Stockholm) 91: 484,494. Abstract As the number of spermatozoal characters being described in reptiles increases, it is important to detail the ontogeny of the features leading to the mature morphology of the spermatozoa which may give rise to more comprehensive data matrices for future phylogenetic analyses within the Reptilia. Therefore, spermiogenically active testes from Anolis lineatopus were investigated ultrastructurally to describe the intracellular changes that occur throughout spermiogenesis. The primary events of spermiogenesis (acrosome formation, nuclear condensation, and elongation) seen in A. lineatopus are similar to those previously described for other amniotes. Characters including a round perforatorium tip, stopper-like perforatorial base plate, open pits of nucleoplasm during condensation, and protein layers within the acrosome complex corroborate trends from previous studies in squamates. However, uniquely defined in A. lineatopus are the excessive amounts of endoplasmic reticulum and Golgi complexes that contribute to cellular secretions during mid elongation of the spermatids and the lack of a manchette. During acrosome formation, the acrosome granule is found in a basal rather than an apical position, which has been observed in previous studies. These similarities and differences observed during spermiogenesis may be helpful in elucidating the development of mature spermatozoal characters as well as aid in future phylogenetic analyses. [source]

XAS, ESR and Potentiometric Studies of Three Dinuclear N,N, -para -Xylylenebis(tetraazamacrocycle)copper(II) Complexes , X-ray Crystal Structure of [N,N,- p -Xylylenebis(cyclen)]copper(II)

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2003
Mathieu Soibinet
Abstract Dicopper complexes with N,N, - p -xylylenebis(cyclam or cyclen) and with the heteroditopic N,N, - p -xylylenebis(cyclam-cyclen) were synthesized. An X-ray study of the N,N, - p -xylylenebis(cyclen)dicopper complex showed that the copper(II) ion is five-coordinate with an H2O molecule in apical position. With this ligand, a polymeric chain was also obtained in the presence of KSCN. The terminal donor atoms of the bridging NCS, anion are coordinated in apical position to the square-pyramidal copper(II) ion. Two alternating kinds of Cu2L4+ moieties are present in the chain, the first with two N4S chromophores and the second with two N5 chromophores. EXAFS and XANES results are in agreement with a five-coordinate copper ion in the cyclen unit and a six-coordinate copper ion in the cyclam unit. Thermodynamic constants were determined by potentiometry. The existence of dinuclear Cu2L4+ species (ligand/metal ratio < 1) and mononuclear CuLHn(2+n)+ species (ligand/metal ratio > 1) were confirmed by an ESR study at variable pH. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

The chiral helical structure of a copper(II) complex with a tridentate Schiff base ligand

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009
Wen-Juan Shi
In the title salt, catena -poly[[[aquacopper(II)]-,-3-(2-pyridylmethyleneamino)propanoato-,4N,N,,O:O,] perchlorate], {[Cu(C9H9N2O2)(H2O)]ClO4}n, the monomeric unit contains a square-based pyramidal CuII centre. The four basal positions are occupied by a tridentate anionic Schiff base ligand which furnishes an NNO-donor set, with the fourth basal position being occupied by an O-donor atom from the carboxylate group of an adjacent Schiff base ligand. The coordination sphere is completed by a water molecule at the apical position. Interestingly, each carboxylate group in the ligand forms a syn,anti -configured bridge between two CuII centres, leading to left-handed chiral helicity. The framework also exhibits O,H...O hydrogen bonds involving the water molecules and an O atom of the perchlorate anion. [source]

(Acetato-,O)aqua(1H -imidazole-,N3)(picolinato-,2N,O)copper(II) 0.87-hydrate: a Z,> 1 structure

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009
Anne-Christine Chamayou
The crystal structure of the title compound, [Cu(C6H4NO2)(C2H3O2)(C3H4N2)(H2O)]·0.87H2O, has a square-pyramidal-coordinated CuII centre (the imidazole is trans to the picolinate N atom, the acetate is trans to the picolinate ,CO2 group and the aqua ligand is in a Jahn,Teller-elongated apical position) and has two symmetry-independent molecules in the unit cell (Z, = 2), which are connected through complementary imidazole,picolinate N,H...O hydrogen bonding. The two partially occupied solvent water molecules are each disordered over two positions. The disordered solvent water molecules, together with pseudosymmetry elements, support the notion that a crystal structure with multiple identical chemical formula units in the structural asymmetric unit (Z, > 1) can represent a crystal `on the way', that is, a kinetic intermediate form which has not yet reached its thermodynamic minimum. Neighbouring molecules form ,,, stacks between their imidazole and picolinate N-heterocycles, with centroid,centroid distances in the range 3.582,(2),3.764,(2),Å. [source]

Synthesis, crystal structure and electrochemical properties of three isocloso eleven-vertex ferrocenecarboxylate ruthenaborane clusters

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2006
Jianmin Dou
Abstract The reaction of [RuCl2(PPh3)3] with closo -[B10H10]2, and C5H5FeC5H4COOH (FcCO2H) in refluxing CH2Cl2 solution affords three ruthenaborane clusters: [PPh3(H2O)(FcCO2)RuB10H8Cl] (1), [(PPh3)2ClRu(PPh3)(FcCO2)RuB10H9]·0.5CH2Cl2 (2 × 0.5CH2Cl2) and [PPh3(FcCO2)2RuB10H8] (3). All of these compounds are characterized by FT-IR, NMR spectroscopic techniques, elemental analysis and single-crystal X-ray analysis. They are all based on a closo -type 1:2:4:2:2 {RuB10} stack with the metal occupying the unique six-connected apical position and can be considered as having isocloso structures derived from the complete capping of the open face of an arachano geometry to give a completely closed deltahedral cluster. Compounds 1 and 2 both have an exo -polyhedral ferrocenecarboxylate that is attached with one {RuO} and one {BO} bond each, resulting in one exo -cyclic five-membered RuOCOB ring. There is in addition one exo -polyhedral ruthenium atom bonded to the center {RuB10} cluster via one {RuRu} linkage and two {RuHµB} bridges, which forms a closed exo -polyhedral tetrahedron configuration in compound 2. Compound 3 has two exo -polyhedral ferrocenecarboxylates to form two five-membered RuOCOB rings engendering a symmetrical conformation. All of these new 11-vertex ruthenaboranes can be considered as having isocloso structures derived from the complete capping of the open face of an arachano geometry to give a completely closed deltahedral cluster. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Crystallographic report: 2-Furfurylgermatrane

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2004
Edmunds Lukevics
Abstract The germanium atom is penta-coordinated and adopts a trigonal bipyramidal geometry. The 2-furfuryl group and the nitrogen atom each occupy an apical position with a transannular N,Ge bond distance of 2.173(3) Å. Copyright © 2004 John Wiley & Sons, Ltd. [source]

catena -Poly­[[bis­[,-1,2-bis(1-methyl­tetrazol-5-yl)­ethane-,2N4:N4,]bis[chloro­copper(II)]]-di-,-chloro]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2003
Dmitry O. Ivashkevich
In the title compound, [Cu2Cl4(C6H10N8)2]n, the ligand has C2 symmetry, and the Cu and Cl atoms lie on a mirror plane. The coordination polyhedron of the Cu atom is a distorted square pyramid, with the basal positions occupied by two N atoms from two different ligands [Cu,N,=,2.0407,(18),Å] and by the two Cl atoms [Cu,Cl,=,2.2705,(8) and 2.2499,(9),Å], and the apical position occupied by a Cl atom [Cu,Cl,=,2.8154,(9),Å] that belongs to the basal plane of a neighbouring Cu atom. The [CuCl2(C6H10N8)]2 units form infinite chains extending along the a axis via the Cl atoms. Intermolecular C,H,Cl contacts [C,Cl,=,3.484,(2),Å] are also present in the chains. The chains are linked together by intermolecular C,H,N interactions [C,N,=,3.314,(3),Å]. [source]

Transition metal complexes with thiosemicarbazide-based ligands.

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2002
XLIV.
The title complex, [Cu(NO3)(C10H14N4O2S)(H2O)](NO3), is the first metal complex with a Schiff base derived from iso­thio­semicarbazide and pyridoxal (pyridoxal is 3-hydroxy-5-­hydroxy­methyl-2-methyl­pyridine-4-carbox­aldehyde). The CuII environment is a square pyramid, the equatorial plane of which is formed by the tridentate ONN -coordinated iso­thio­semicarbazone and one water mol­ecule, while the nitrate ligand is in the apical position. The existence of numerous strong intermolecular hydrogen bonds, and weak C,H,O and C,H,, interactions, leads to a three-dimensional supramolecular structure. [source]

A Micellar Multitasking Device: Sensing pH Windows and Gauging the Lipophilicity of Drugs with Fluorescent Signals

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2010
Franck Denat Prof.
Abstract A multitasking fluorescent device can be obtained by forming micelles of Triton,X-100, containing a lipophilic macrocyclic Cu2+ complex and the coordinating fluorophore Coumarin,343 (C343), which features a COOH moiety. At low pH the two micellised components do not interact, and the fluorescence of Courmarin,343 (C343) is intense. At intermediate pH, C343 is deprotonated and coordinates to the Cu2+ centre in its apical position, with fluorescence quenching. At higher pH the deprotonated C343 is displaced from Cu2+ by the formation of an OH, complex, and the fluorescence is revived. This allows the system to carry out its first task as it behaves as an "on,off,on" fluorescent sensor for pH windows. The "off" part of the window ranges from pH,6 to 8. In this interval, in which the carboxylate form of C343 is apically coordinated to the Cu2+ complex inside micelles, the device carries out its second task, that is, it behaves as a gauge for lipophilicity. For pHs between 6 and 8, molecules containing a COOH group are in their COO, form and distribute between bulk water and micelles proportionally to their lipophilicity. Upon entering the micelle, their COO, moiety competes for coordination with C343, displacing it from the Cu2+ centre, and this results in fluorescence revival, the intensity of which is also proportional to the lipophilicity of the examined molecule. We have chosen the physiological pH value (7.4) as the working pH, and we have examined the lipophilicity of fatty acids and of the widely used family of non-steroidal anti-inflammatory drugs (NSAIDs). The device successfully measures their lipophilicity, expressing it with an "off,on" type fluorescent signal, as demonstrated by the correlation of the fluorescence increase with the logarithmic water/octanol partition coefficient (log,P) and with the difference between the pKa observed in micelles and that measured in water for NSAIDs. [source]

Synthesis and Crystal Structure of Two iso - closo 11-Vertex p -Bromobenzoate Ruthenoborane Clusters: [(PPh3)(p -BrC6H4CO2)2RuB10H8] and [(PPh3)2Ru(p -BrC6H4CO2)-(PPh3)RuB10H9]

CHINESE JOURNAL OF CHEMISTRY, Issue 12 2006
Qing-Liang Guo
Abstract The title clusters [(PPh3)(p -BrC6H4CO2)2RuB10H8] (1) and [(PPh3)2Ru(PPh3)(p -BrC6H4CO2)RuB10H9] (2) have been prepared and characterized by elemental analysis, FT-IR, 1H, 13C NMR spectra and single-crystal X-ray diffraction analysis. The clusters crystallize in monoclinic system, space group C2/c, with a=2.569(4) nm, b=1.546(2) nm, c=1.927(3) nm, ,=95.11(2)°, Z=8, V=7.622(21) nm3, Dc=1.533 Mg/m3, F(000)=3472, S=1.009, R=0.0418, wR=0.0775 and triclinic system, space group P -1, with a=1.3142(3) nm, b=1.3761(3) nm, c=1.8503(4) nm, ,=90.445(4)°, ,=105.950(4)°, (=108.980(4)°, Z=2, V=3.0251(12) nm3, Dc=1.434 Mg/m3, F(000)=1316, S=1.007, R=0.0464, wR=0.1175, respectively for 1 and 2. In the structures, both of the clusters are based on a closo -type C2v 1:2:4:2:2 RuB10 stack with the metal occupying the unique six-connected apical position. In cluster 1, the metal center has three exo -polyhedral ligands:one triphenylphosphine and two dative oxygen atoms of p -bromobenzoates. The other oxygen atoms of two p -bromobenzoate are additionally bonded to B(2) and B(3) atoms respectively, resulting in two exo -cyclic five-membered Ru-O-C-O-B rings and engendering a symmetrical conformation. The cluster 2 is a bimetallic species in which the second ruthenium is bound to the {RuB10} center via one Ru,Ru bond and two {RuHµB} bridges resulting in one closo distorted exo -polyhedral Ru(1)- Ru(2)-B(3)-B(6) tetrahedron. [source]

First (Peroxo)vanadium(V) Complex with Heteroligand Formed in Reaction System , Synthesis, Structure and Reactivity of K[VO(O2)(omeida)]·H2O {omeida = N -[2-(2-oxomorpholine-4-yl)ethyl]iminodiacetato(2,)}

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2003
Michal Sivįk
Abstract The crystalline peroxo complex of vanadium(V), K[VO(O2)(omeida)]·H2O, where omeida is a ,-lactone derivative, N -[2-(2-oxomorpholine-4-yl)ethyl]iminodiacetate(2,), has been obtained by reaction of vanadate with H2O2 and N -(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) in acidic aqueous solution at pH = 3 and 278 K. X-ray analysis revealed a distorted pentagonal-bipyramidal coordination around the vanadium atom, with a typical cis arrangement of oxo and peroxo ligands in apical and equatorial positions, respectively. Two amino nitrogen atoms of the tetradentate omeida(2,)-N1,N2,O1,O2 ligand occupy the neighbouring equatorial positions of the pentagonal plane, and two oxygen atoms of carboxymethyl groups bound to the same N1 nitrogen atom are in equatorial and apical positions. The six-membered lactone ring in omeida was formed in the reaction solution from carboxy and hydroxy groups not involved in coordination with the vanadium atom. The 51V NMR spectra of K[VO(O2)(omeida)]·H2O, and of peroxovanadate/HEDTA/H2O and vanadate/HEDTA/H2O solutions, as well as the 1H NMR spectrum of HEDTA, proved that lactone ring closure proceeds only in peroxovanadate but not vanadate solutions. Spectroscopic investigation of the oxygen transfer reaction from the peroxo ligand in [VO(O2)(omeida)], to the thiolato sulfur atom in [Co(en)2{S(CH2)2NH2}]2+ or [Co(en)2(cyst)]+, and of the oxidation of N -acetyl- L -cysteine by K[VO(O2)(omeida)]·H2O, revealed much more complicated reaction mechanisms than those of other (amino-polycarboxylato)monoperoxo complexes of vanadium(V). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Translocation of 14C-sucrose within the Ear in Durum and Aestivum Wheat Varieties

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2001
I. Ravi
Excised ears of Triticum durum (HD 4502 and B 449) and T. aestivum (Kalyansona and Kundan) varieties were cultured in 14C-sucrose, and the uptake and distribution of 14C within the ear was examined. Species-level differences in the distribution of 14C to spikelets at basal, middle and apical positions in the wheat ear (vertical distribution) were observed. T. aestivum var. Kalyansona and Kundan showed no limitation in vertical translocation of 14C-sucrose, whereas in T. durum there was a decrease in the distribution of 14C to apical spikelets. Within a spikelet, the distribution of 14C-sucrose to distal grains was significantly less than that to proximal grains in all the genotypes. Translokation von 14C-Sukrose innerhalb der Ähre von Durum-und Aestivumweizen-varietäten Abgetrennte Ähren von T. durum (HD 4502 und B 449) und T. aestivum (Sorten: Kalyansona und Kundan) wurden in14C-Sukrose kultiviert und Aufnahme und Verteilung von14C innerhalb der Ähren untersucht. Die artspezifischen Differenzen in der Verteilung von14C im Hinblick auf die Ährchen im basalen, mittleren und apikalen Teil der Weizenähre (vertikale Verteilung) wurden beobachtet. Triticum aestivum var. Kalyansona und Kundan zeigten keine Limitierung in der vertikalen Translokation von14C-Sukrose, während bei Triticum durum eine Abnahme in der Verteilung von14C zum apikalen Ährchen vorlag. Innerhalb der Ährchen war die Verteilung von14C-Sukrose zu den distalen Körnern bei allen Genotypen signifikant geringer als zu den proximalen Körnern. [source]

Synthesis, properties and crystal structural characterization of diorganotin(IV) derivatives of 2-mercapto-6-nitrobenzothiazole

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2003
Chunlin Ma
Abstract The diorganotin(IV) dichlorides R2SnCl2 (R: Ph, PhCH2 or n -Bu) react with 2-mercapto-6-nitrobenzothiazole (MNBT) in benzene to give [Ph2SnCl(MNBT)] (1), [(PhCH2)2Sn(MNBT)2] (2) and [(n -Bu)2Sn(MNBT)2] (3). The three complexes have been characterized by elemental analysis and IR, 1H, 13C and 119Sn NMR spectroscopies. X-ray studies of the crystal structures of 1, 2 and 3 show the following. The tin environment for complex 1 is distorted cis-trigonal bipyramid with chlorine and nitrogen atoms in apical positions. The structure of complex 2 is a distorted octahedron with two benzyl groups in the axial sites. The geometry at the tin atom of complex 3 is that of an irregular octahedron. Interestingly, intra-molecular non-bonded Cl,S interactions and S,S interaction were recognized in the crystallographic structures of 1 and 3 respectively. As a result, complex 1 is a polymer and complex 3 is a dimer. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Tetraaqua-1,4O -bis(,-caprolactam-1,O)-,-cyano-1:2,2N:C -pentacyano-2,5C -iron(III)yttrium(III), a novel cyano-bridged dinuclear complex

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2002
Yi He
Using caprolactam as a ligand, the novel title cyano-bridged yttrium(III),ferricyanide complex, [Y(caprolactam)2(H2O)4Fe(CN)6] or [FeY(CN)6(C6H11NO)2(H2O)4], has been synthesized and structurally characterized. The Y atom is seven-coordinate and has approximately pentagonal,bipyramidal stereochemistry, with water mol­ecules occupying apical positions. Of the five ligands in equatorial positions, one is the N -bound bridging cyano group, and flanking this are two O -­bound caprolactam moieties, which are markedly inclined towards the bridged ferricyanide moiety such that they partially envelop it. Water mol­ecules occupy the remaining two equatorial positions. The Y,N,C,Fe,C,N sequence of atoms lies on a crystallographic twofold axis and is therefore perfectly linear, which has not been observed previously in cyano-bridged bimetallic complexes. [source]

Transition metal complexes with ­thiosemicarbazide-based ligands.

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2002
XLIII.
In the title compound, [ZnCl(C2H7N3S)2]Cl, the ZnII ion is five-coordinated in a distorted trigonal,bipyramidal arrangement, with the hydrazine N atoms located in the apical positions. The structure is stabilized by N,H,Cl hydrogen bonds, which involve both the Cl atoms and all the hydrogen donors, except for one of the two thio­amide N atoms. A comparison of the geometry of thio­semicarbazide and S -­methyl­iso­thio­semicarbazide complexes with ZnII, CuII and NiII shows the pronounced influence of the hydrogen-bond network on the coordination geometry of ZnII compounds. [source]

Syntheses, Crystal and Solution Structures, Ligand-Exchange, and Ligand-Coupling Reactions of Mixed Pentaarylantimony Compounds

CHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2007
Günter Schröder Dr.
Abstract All possible combinations of mixed pentaarylantimony compounds bearing p -methylphenyl and p -trifluoromethylphenyl groups were synthesized; ArnTol5,nSb (n=0,5: Ar=p -CF3C6H4, Tol=p -CH3C6H4): Tol5Sb (1), ArTol4Sb (2), Ar2Tol3Sb (3), Ar3Tol2Sb (4), Ar4TolSb (5), and Ar5Sb (6). Compounds 2,5 are the first well-characterized examples of mixed acyclic pentaarylantimony species. The structures of 2,6 were determined by X-ray crystallography to feature trigonal-bipyramidal (TBP) geometry with the more electronegative p -trifluoromethylphenyl substituents selectively occupying the apical positions. Consideration of the chemical shifts of the ipso carbons of the aryl and tolyl groups suggested that the solution structures of 1,6 were also TBP, although their pseudorotation could not be frozen even at ,80,°C. Ligand-exchange reactions (LERs) took place between 1 and 6 at ,60,°C in [D6]benzene and all six species 1,6 were found in the equilibrium mixture. The relative stabilities of 1,6 were determined quantitatively by comparison of the observed molar ratios of 1,6 in equilibrium with calculated statistical molar ratios, and Ar2Tol3Sb (3) was found to be the most stable. The ligand-coupling reactions (LCRs) of 2,5 in solution were greatly accelerated by adding Cu(acac)2 or Li+TFPB, (TFPB: [3,5-(CF3)2,C6H3]4,B), whereby the rate becomes comparable to the LER. The use of flash vacuum thermolysis (FVT) allowed the LCR to occur with very little ligand-exchange; the exception ArTol4Sb had very fast ligand-exchange. The selectivities of the LCRs were calculated from the yield of the biaryls synthesized by using FVT. These results were highly consistent with reactions catalyzed in solution, in which bitolyl was not obtained at all. The experimental results suggested that the LCR of pentaarylantimony compounds proceeds in the manner of apical,apical coupling. [source]

The Effect of Counterion/Ligand Interplay on the Activity and Stereoselectivity of Palladium(II),Diimine Catalysts for CO/p -Methylstyrene Copolymerization

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007
Barbara Binotti Dr.
Abstract The catalytic activity and stereoselectivity of complexes [Pd(,1,,2 -C8H12OMe)(ArNC(R,)C(R,)NAr)]X in the copolymerization of CO and p -methylstyrene have been correlated with their interionic structure in solution and in the solid state, as determined by 19F,1H-HOESY NMR spectroscopy and X-ray diffraction studies, respectively. The highest productivity is obtained with unhindered diimine ligands bearing electron-donating substituents and with the least coordinating counterion. Copolymers with a microstructure ranging from atactic to predominantly isotactic are obtained. The degree of isotacticity increases as the steric hindrance in the apical positions and the coordinating ability of the counterion increase. The counterion is located close to the diimine in both solution and the solid state but it moves toward the palladium as the steric hindrance in the apical positions decreases. When the latter is small the counterion competes with the substrate for apical coordination, and consequently it affects the productivity. In the case of ortho -dimethyl-substituted ligands the counterion is confined in the back, above the NC(R,)C(R,)N moiety, and does not affect the productivity. However, it contributes to increasing the stereoregularity of the copolymer by making the aryl moieties more rigid. With R,=Me and Ar=o -Me2C6H3 an ll of 81,% and 72,% was obtained with X,=CF3SO3, or BArF,, respectively. The isotacticity of the copolymers produced by ortho -monosubstituted catalysts depends greatly on the counterion and ranges from 30,% to 59,% with X,=BArF, and X,=CF3SO3,, respectively, with Ar=o -EtC6H4 and R,=Me. Based on the interionic structural results, this effect can be explained by a greater reduction of the copolymerization rate of Cs -symmetric isomers with respect to their C2 -symmetric counterparts. [source]

Synthesis, Crystal Structures and Photoluminescence Properties of Two 2D Coordination Polymer Compounds with Drug Ligand Enoxacin

CHINESE JOURNAL OF CHEMISTRY, Issue 7 2006
Liang-Cai Yu
Abstract Two new 2D coordination polymers of [M(Enox)2]·C2H5OH (MZn, 1 and Co, 2; HEnox=1,4-dihydro- 1-ethyl-6-fluoro-4-oxo-7-piperazine-1,8-naphtyridine-3-carboxylic acid) were synthesized under hydrothermal conditions. The single crystal X-ray diffraction analyses showed that 1 and 2 are isostructural. The Zn(II) in 1 and Co(II) ions in 2 are six-coordinated in an octahedral environment with an equatorial plane composed of four oxygen atoms:two of them from the 4-oxo and the other two from 3-carboxylate of two coordinated Enox ligands, forming a stable six-membered chelating ring with the apical positions occupied by two N atoms of the piperazinyl rings. Thus, the molecules were self-assembled into a 2D neutral square grid with cavity dimensions of 1.3399 nm×1.3399 nm for 1 and 1.3389 nm×1.3389 nm for 2, respectively. Compound 1 emits strong blue fluorescence on irradiation by UV light in the solid state at room temperature. [source]