Ring Linkage Research Articles

A Cembranoid, Trocheliophorol, from the Cultured Soft Coral Sarcophyton trocheliophorum

Abstract A new cembranoid, trocheliophorol (1), and a known cembranoid sarcophine have been isolated from the cultured soft coral Sarcophyton trocheliophorum. The structure of 1 was determined on the basis of extensive spectroscopic analysis. Compound 1 is the first α,β-unsaturated-γ-lactone cembrane that was found to possess a tetrahydrofuran moiety with an 8,11-ether linkage in a 14-membered ring.

Methyl β-allolactoside [methyl β-D-galactopyranosyl-(1→6)-β-D-glucopyranoside] monohydrate

Methyl beta-allolactoside [methyl beta-D-galactopyranosyl-(1-->6)-beta-D-glucopyranoside], (II), was crystallized from water as a monohydrate, C(13)H(24)O(11).H(2)O. The betaGalp and betaGlcp residues in (II) assume distorted (4)C(1) chair conformations, with the former more distorted than the latter. Linkage conformation is characterized by phi' (C2(Gal)-C1(Gal)-O1(Gal)-C6(Glc)), psi' (C1(Gal)-O1(Gal)-C6(Glc)-C5(Glc)) and omega (C4(Glc)-C5(Glc)-C6(Glc)-O1(Gal)) torsion angles of 172.9 (2), -117.9 (3) and -176.2 (2) degrees , respectively. The psi' and omega values differ significantly from those found in the crystal structure of beta-gentiobiose, (III) [Rohrer et al. (1980). Acta Cryst. B36, 650-654]. Structural comparisons of (II) with related disaccharides bound to a mutant beta-galactosidase reveal significant differences in hydroxymethyl conformation and in the degree of ring distortion of the betaGlcp residue. Structural comparisons of (II) with a DFT-optimized structure, (II(C)), suggest a link between hydrogen bonding, pyranosyl ring deformation and linkage conformation.

3,3′,5,5′-Tetranitrobiphenyl

The title compound, C12H6N4O8, is a biphenyl system that was synthesized as a building block for a new series of anti­malarial compounds. The aromatic rings are oriented at a dihedral angle of 45.5 (2)°, and inter­molecular short O⋯O contacts form a chain along the b axis. The strength of the inter­actions involved in this chain cause one of the rings to be slightly distorted, with the torsion angle between the nitro groups being 23.4 (2)°, whereas, in the other ring, both nitro systems are parallel, forming an angle of 9.6 (2)° with the plane of the aromatic ring to which they are bound. Furthermore, the three ring C atoms around the ring–ring linkage belong to a plane inclined by 4.5 (1)° in relation to the plane containing the other three C atoms, i.e. (NO2–)C—C—C(NO2). This distortion of the ring causes uncommonly short intermolecular O⋯O [3.038 (2) Å] and O⋯C [3.000 (4) and 3.214 (1) Å] contacts.

Syntheses, Crystal Structures, and Gas Storage Studies in New Three-Dimensional 5-Aminoisophthalate Praseodymium Polymeric Complexes

The hydrothermal reaction of 5-aminoisophthalic acid and praseodymium oxide in different acids results in two new praseodymium coordination polymers, {Pr(2)(aip)(3)(H(2)O)(2) x 3 H(2)O}(n) (1) and {Pr(2)(Haip)(2)(aip)(NO(3))(2) x 8 H(2)O}(n) (2) (aip = 5-aminoisophthalate). Complexes 1 and 2 are two distinct three-dimensional metal-organic frameworks constructed from the linkage of rod-shaped praseodymium carboxylate secondary building units and phenyl rings. Both dehydrated coordination frameworks are estimated using a computational method based on Connolly's algorithm, indicating that dehydrated compound 1 cannot host molecules other than water molecules or He, whereas dehydrated compound 2 is able to host molecules with kinetic radii as big as 2.3 A. The potential specific accessible surface of this compound is 792 m(2) g(-1). Meanwhile, N(2) sorption measurements reveal that dehydrated compound 2 having a high 230 cm(3)/g (287 mg/g) N(2) storage capacity at 77 K and 1 atm is in fairly good agreement with our calculation results. Moreover, powder X-ray diffraction measurement results demonstrated that the stable channels of dehydrated compound 2 can reversibly host other small solvent molecules (e.g., water, methanol, and ethanol) and grand canonical Monte Carlo simulation is applied to predict its hydrogen storage capacity.

Poly(hydroxyether of bisphenol A) ‐alt‐polydimethylsiloxane: a novel thermally crosslinkable alternating block copolymer

AbstractBACKGROUND: An important strategy for making polymer materials with combined properties is to prepare block copolymers consisting of well‐defined blocks via facile approaches.RESULTS: Poly(hydroxyether of bisphenol A)‐block‐polydimethylsiloxane alternating block copolymers (PH‐alt‐PDMS) were synthesized via Mannich polycondensation involving phenolic hydroxyl‐terminated poly(hydroxyether of bisphenol A), diaminopropyl‐terminated polydimethylsiloxane and formaldehyde. The polymerization was carried out via the formation of benzoxazine ring linkages between poly(hydroxyether of bisphenol A) and polydimethylsiloxane blocks. Differential scanning calorimetry and small‐angle X‐ray scattering show that the alternating block copolymers are microphase‐separated. Compared to poly(hydroxyether of bisphenol A), the copolymers displayed enhanced surface hydrophobicity (dewettability). In addition, subsequent crosslinking can occur upon heating the copolymers to elevated temperatures owing to the existence of benzoxazine linkages in the microdomains of hard segments.CONCLUSION: PH‐alt‐PDMS alternating block copolymers were successfully obtained. The subsequent self‐crosslinking of the PH‐alt‐PDMS alternating block copolymers could lead to these polymer materials having potential applications. Copyright © 2008 Society of Chemical Industry

Synthesis and Reactivity of Tantalum Complexes Supported by Bidentate X2 and Tridentate LX2 Ligands with Two Phenolates Linked to Pyridine, Thiophene, Furan, and Benzene Connectors: Mechanistic Studies of the Formation of a Tantalum Benzylidene and Insertion Chemistry for Tantalum−Carbon Bonds

Using either alkane elimination or salt metathesis methods, tantalum complexes have been prepared with new ligand systems with tridentate bis(phenolate)donor (donor = pyridine, furan, and thiophene) or bidentate bis(phenolate)benzene arrangements. The ligand framework has two X-type phenolates connected to the flat heterocyclic L-type donor at the 2,6- or 2,5- positions or to the 2,6- positions of benzene via direct ring−ring (sp_2−sp_2) linkages. Solid-state structures of these complexes show that in all cases the ligands bind in a mer fashion, but with different geometries of the LX_2 frameworks. The pyridine-linked system binds in a Cs-fashion, the furan-linked system in a C2_v-fashion, and the thiophene-linked system in a C_1-fashion. A bis(phenolate)pyridine tantalum tribenzyl species (7), upon heating in the presence of dimethylphenylphosphine, generates a stable benzylidene complex by α-hydrogen abstraction with loss of toluene and PMe_2Ph trapping. This process was found to be independent of PMe_2Ph concentration with ΔH = 31.3 ± 0.6 kcal·mol−1 and ΔS = 3 ± 2 cal·mol−1·K−1, and the kinetic isotope effect kH/kD = 4.9 ± 0.4, consistent with a mechanism involving rate determining α-hydrogen abstraction with loss of toluene, followed by fast phosphine coordination to the resulting benzylidene species. An X-ray structure determination reveals that the benzylidene π-bond is oriented perpendicular to the oxygen−oxygen vector, in accord with the prediction of DFT calculations. Tantalum alkyl complexes with the benzene-linked bis(phenolate) ligand (Ta(CH_3)2[(OC_6H_2-tBu_2)2C_6H_3] (16), Ta(CH_2Ph)2[(OC_6H_2-tBu_2)2C_6H_3] (17), and TaCl_2CH_3[(OC_6H_2-tBu_2)2C_6H_4] (18)) are obtained with (to afford pincer complexes) or without cyclometalation at the ipso-position. Deuterium labeling of the phenol hydrogens and of the linking 1,3-benzene-diyl ring reveals an unexpected mechanism for the metalation of bis(phenol)benzene with TaC_l2(CH_3)3 to generate 18. This process involves protonolysis of a methyl group, followed by C-H/Ta-CH_3 σ bond metathesis leading to cyclometalation of the linking ring, and finally protonation of the cyclometallated group by the pendant phenol. TaCl_2CH_3[(OC_6H_2-tBu_2)2C_6H_4] was found to undergo σ bond metathesis at temperatures over 90 °C to give the pincer complex TaCl_2[(OC_6H_2-tBu_2)2C_6H_3] (1_9) and methane (ΔH = 27.1 ± 0.9 kcal·mol−1; ΔS≠ = −2 ± 2 cal·mol^1·K^1; k_H/k_D = 1.6 ± 0.2 at 125 °C). Ta(CH_3)_2[(OC_6H_2-tBu_2)_2C_6H_3] (16) was found to react with tBuNC to insert into the Ta-CH_3 bonds and generate an imino-acyl species (23). Reaction of 16 with Ph_2CO or PhCN leads to insertion into the Ta-Ph bond to give 21 and 22. Complexes 6, 7, 10, 11-P, 12, 13, 17, 18, 19-OEt_2, 21, 22, and 23 have been structurally characterized by single crystal X-ray diffraction, and all show a mer binding mode of the diphenolate ligands, but the ligand geometry varies leading to C_2v-, pseudo-C_s-, pseudo-C_2-, and C_1-symmetric structures.

Zirconium and Titanium Complexes Supported by Tridentate LX2 Ligands Having Two Phenolates Linked to Furan, Thiophene, and Pyridine Donors: Precatalysts for Propylene Polymerization and Oligomerization

Zirconium and titanium complexes with tridentate bis(phenolate)−donor (donor = pyridine, furan and thiophene) ligands have been prepared and investigated for applications in propylene polymerization. The ligand framework has two “X-type” phenolates connected to the flat heterocyclic “L-type” donor at the 2,6- or 2,5- positions via direct ring−ring (sp2−sp2) linkages. The zirconium and titanium dibenzyl complexes have been prepared by treatment of the neutral bis(phenol)−donor ligands with M(CH2Ph)4 (M = Ti, Zr) with loss of 2 equiv of toluene. Titanium complexes with bis(phenolate)pyridine and -furan ligands and zirconium complexes with bis(phenolate)pyridine and -thiophene ligands have been characterized by single-crystal X-ray diffraction. The solid-state structures of the bis(benzyl)titanium complexes are roughly C2-symmetric, while the zirconium derivatives display Cs and C1 symmetry. The bis(phenolate)pyridine titanium complexes are structurally affected by the size of the substituents (CMe3 or CEt3) ortho to the oxygens, the larger group leading to a larger C2 distortion. Both titanium and zirconium dibenzyl complexes were found to be catalyst precursors for the polymerization of propylene upon activation with methylaluminoxane (MAO). The activities observed for the zirconium complexes are particularly notable, exceeding 106 g polypropylene/mol Zr·h in some cases. The bis(phenolate)pyridine titanium analogues are about 103 times less active, but generate polymers of higher molecular weight. When activated with MAO, the titanium bis(phenolate)furan and bis(phenolate)thiophene systems were found to promote propylene oligomerization.

Bismaleimides, bisnadimides, and polyaspartimides containing ether and ester linkages and pyridine

AbstractA series of bismaleimides (BMI) and bisnadimides (BNI) containing pyridine ring and flexible linkages were prepared and the structural characterization of the resins was carried out by elemental analysis, FTIR, 1H NMR, and 13C NMR spectroscopy. Their curing behavior were characterized by differential scanning calorimetry and thermal stability of the cured resins were investigated by thermogravimetric analysis. In addition, a series of polyaspartimides were prepared by the polyaddition of the bismalemide with various dimaines. The polymers were characterized by FT‐IR, inherent viscosity, and molecular weight measurements. All the polyimides were soluble in many organic solvents, the glass transition temperature of the polyaspartimides are in the range of 194–231°C, 10% weight loss (T10) takes place in the temperature range of 379–482°C in N2 and char yield in the range of 44.31–53.31%. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymer and its nanostructured blends with epoxy resin

Mannich condensation was utilized to synthesize poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymer (PH-alt-PDMS). The polymerization between the phenolic hydroxyl-terminated oligo(hydroxyether of bisphenol A) and amino-terminated oligodimethylsiloxane with the defined lengths was carried out via the formation of benzoxazine ring linkages, which was mediated with paraformaldehyde. The alternating block copolymer was characterized by means of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). The block copolymer was incorporated to prepare nanostructured thermosetting blends. The nanostructures of the thermosetting blends were investigated by means of atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). The formation of the nanostructures in the thermosetting composites was judged to follow the self-assembly mechanism in terms of the difference in miscibility of PDMS and PH subchains with epoxy resin after and before curing reaction. The fracture toughness of the nanostructured blends was evaluated in terms of the measurement of stress field intensity factor (KIC). It is noted that the epoxy resin was significantly toughened.

Structural Diversity in Expanded Porphyrins

Inspired by the chemistry of porphyrins, in the last decade, a new research area where porphyrin analogues such as expanded, isomeric, and contracted porphyrins have been synthesized, and their chemistry has been exploited extensively. Expanded porphyrins are macrocyclic compounds where pyrrole or heterocyclic rings are connected to each other through meso carbon bridges. Depending on the number of pyrrole rings in conjugation or the number of double bonds linking the four pyrrole rings expanded porphyrins containing up to 64 pi electrons are reported in the literature. The interest in these systems lies in their potential applications as anion binding agents, as photosensitizers for photodynamic therapy (PDT), in antisensing applications, as MRI contrasting agents, and more recently, as material for nonlinear optical application. Expanded porphyrins containing more than four pyrrole or heterocyclic rings, such as sapphyrin (five pyrrole), rubyrin (six pyrrole), heptaphyrin (seven pyrrole), and octaphyrin (eight pyrrole), are reported in the literature. Furthermore, substituents on expanded porphyrins can be attached either at the meso carbons or at beta-pyrrole positions. beta-substituted expanded porphyrins generally adopt normal structure where all the pyrrole nitrogens point inward in the cavity 1, while the meso-substituted expanded porphyrins exhibit normal 2, inverted 3, fused 4, confused 5, and figure eight 6 conformations. The conformation of expanded porphyrin is dependent on the nature of the linkage of the heterocyclic rings, the nature and the number of the heteroatoms present in the cavity, and the state of protonation. It is possible to change one conformation to another by varying temperature or by simple chemical modification, such as protonation by acids. An understanding of the structure-function correlation in expanded porphyrins is an important step for designing these molecules for their potential applications. In this context, even though several meso aryl expanded porphyrins are reported in literature, there is no comprehensive understanding of structural diversity exhibited by them. In this Account, an attempt has been made to provide a systematic understanding of the conditions and circumstances that lead to various conformations and structures. Specifically, the structural diversities exhibited by five pyrrolic macrocycles to ten pyrrolic macrocycles are covered in this Account. In pentapyrrolic systems, sapphyrins, N-fused, and N-confused pentaphyrins are described. It has been shown that the positions of the heteroatom affect the conformation and in turn the aromaticity. In hexapyrrolic systems, rubyrins and hexaphyrins are covered. The conformation of core-modified rubyrins was found to be dependent on the number and nature of the heteroatom present inside the core. Further, in the hexapyrrolic systems, an increase in the number of meso carbons from four (rubyrin) to six (hexaphyrin) increases the conformational flexibility, where different types of conformations are observed upon going from free base to protonated form. Heptapyrrolic and octapyrrolic expanded porphyrins also exhibit rich structural diversity. Octaphyrins are known to exhibit figure eight conformation, where the macrocycle experiences a twist at the meso carbon, losing aromatic character. By suitable chemical modification, it is possible to avoid the twist, and planar 34 pi core-modified octaphyrins have been reported that show aromatic character and obey the (4 n + 2) Hückel rule. The structural diversity exhibited by nine pyrrolic macrocycles (nonaphyrins) and ten pyrrolic macrocycles (decaphyrins) are also described.

Low Temperature X-ray Structures of Two Crystalline Forms (I) and (II) of the Pyrimidine Derivative and Sodium Channel Blocker BW1003C87: 5-(2,3,5-Trichlorophenyl)-2,4-diaminopyrimidine

The X-ray crystal structures of two crystalline forms of 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine, C10H7Cl3N4 (code name BW1003C87) (I) and (II), have been carried out at liquid nitrogen temperature. A detailed comparison of the two structures is given. Both are centrosymmetric, with structure (I) in the triclinic space group P $$\bar 1,$$ unit cell a = 6.4870(10), b = 9.216(2), c = 12.016(2) A, α = 75.78(3)°, β = 89.95(3)°, γ = 83.45(3)°, V = 691.5(2) A3, Z = 2 and density (calculated) = 1.544 Mg/m3; and (II) in the monoclinic space group P21/c, unit cell a = 12.000(2), b = 7.518(2), c = 13.450(3) A, β = 97.87(3)°, V = 1202.0(5) A3, Z = 4, Density (calculated) = 1.600 Mg/m3. Structure (I) includes a solvated CH3OH in the lattice. Final R indices [I > 2sigma(I)] are R1 = 0.0427, wR2 = 0.1075 for (I) and R1 = 0.0487, wR2 = 0.1222 for (II). R indices (all data) are R1 = 0.0470, wR2 = 0.1118 for (I) and R1 = 0.0623, wR2 = 0.1299 for (II). 5-Phenyl-2,4 diaminopyrimidine and 6-phenyl-1,2,4 triazine derivatives, which include lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine), have been investigated for some time for their effects on the central nervous system. Both lamotrigine and 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine (code name BW1003C87), the subject of the present study, are anticonvulsant as well as neuroprotective in models of brain ischaemia and in a model of white matter ischaemia. BW1003C87 is a sodium channel blocker which also reduces the release of the neurotransmitter glutamate. The three dimensional structures reported here form part of a newly developed data base for the detailed investigation of members of this drug family and their biological activities. Rex A. Palmer, Brian S. Potter, Michael J Leach and Babur Z. Chowdhry 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine occurs in two crystalline forms whose X-ray structures are described here. The molecular conformations in (I) and (II) are quite distinct as illustrated, the ring linkage torsion angle differing by 23.5 deg. (I) has a methanol solvate molecule in the lattice.

X-ray Crystallographic Structures of Two Lamotrigine Analogues: (I) 3,5-Diamino-6-(2-chlorophenyl)-1,2,4-triazine Water Solvate and (II) 3,5-Diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine Methanol Solvate

The X-ray crystal structures of two lamotrigine derivatives (I) 3,5-diamino-6-(2-chlorophenyl)-1,2,4-triazine, C9H8ClN5, (465BL) as a hydrate, and (II) 3,5-diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine, C9H7Cl2N5, (469BR) as a methanol solvate, have been carried out at liquid nitrogen temperature and room temperature, respectively. A detailed comparison of the two structures is given. Both are centrosymmetric with (I) in the orthorhombic space group Pbca, a = 12.2507(3), b = 15.7160(6), c = 21.71496(9) A, Z = 16, and (II) in the monoclinic space group C2/c, a = 38.553(3), b = 4.9586(2), c = 14.546(2) A, β = 111.59(1)°, Z = 8. Final R indices [I > 2sigma(I)] for (I) are R1 = 0.0670, wR2 = 0.1515 and for (II) R1 = 0.0434, wR2 = 0.1185. Structure (I) has water of crystallization in the lattice and (II) includes a solvated CH3OH. Structure (I) is characterized by having two crystallographically independent molecules, A and B, of 465BL, per asymmetric unit. Molecule B has a very unusual feature in that the 2-chlorophenyl ring is statistically disordered, occupying site (1) in 87.5% of the structure and site (2) in 12.5% of the structure. Sites (1) and (2) are related by an exact 180° pivot of the phenyl ring about the ring linkage bond. The presence of two independent molecules per asymmetric unit provides an ideal opportunity for the conformational flexibility of the molecule 465BL to be studied. Structure (I) also includes a further unusual feature in that the lattice contains one fully occupied water molecule and an additional solvated water which is only 33% occupied. Rex A. Palmer, Brian S. Potter, Michael J Leach and Babur Z. Chowdhry The crystal structures of two lamotrigine analogues: (I) 3, 5-diamino-6-(2-chlorophenyl)-1, 2, 4-triazine, water solvate and (II) 3, 5-diamino-6-(3,6-dichlorophenyl)-1, 2, 4-triazine methanol solvate are presented. Structure (I) includes two molecules per asymmetric unit labeled A and B where molecule B is unusually disordered having Cl in either position 2 (87.5% occupied) or position 6 of the phenyl ring (12.5% occupied), the two sites being related by 180deg rotation about the ring linkage bond. Molecule I(A) on the other hand shows no disorder. The relative orientations of the two rings in I(A and B) and in II is shown to be different. Lamotrigine and analogues have been investigated for some time for their effects on the central nervous system. For example both lamotrigine and 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine (code name BW 1003C87) are voltage-gated sodium channel blockers as well as blocking the release of the neurotransmitter glutamate. BW 1003C87 has also been shown to reduce the release of glutamate evoked by veratrine in brain tissue, providing a therapeutic approach in both cerebral ischemia and epilepsy [B. S. Meldrum, J. H. Swan, M. J. Leach, M. H. Millan, R. Gwinn, K. Kadota, S. H Graham, J. Chen, R. P. Simon , Brain Res., 1992, 593, 1.]. This is one of a series of papers on the structures of lamotrigine analogues.

Synthesis, Characterization, and Fluorescence Behavior of Twisted and Planar B2N2-Quaterphenyl Analogues

A series of planar and twisted heteroaromatic quaterphenyl analogues containing BN ring linkages has been synthesized using primarily difunctional Lewis acidic diborabiphenyl moieties as molecular cores. Crystal structure analyses indicated the presence of large twist angles between adjacent aromatic rings in 1 and 3, which were also observed to possess nonfluorescent behavior due to a lack of molecular rigidity and insufficient B=N character in the excited state. In contrast, the incorporation of one or two bridging ethylene groups between the adjacent rings (installed via an ethynyl cycloisomerization) was found to afford planar phenanthrene or pyrene moieties, which resulted in weak fluorescence behavior (Phi F = 0.02-0.16) for the n-Bu and Ph derivatives 5-12. Emission colors ranged from green (lambda em = 521 nm) to red (lambda em = 630 nm) and depended primarily on the conformation (2,2'- vs 4,4'-), the extent of chromophore conjugation (phenanthrene vs pyrene), and the type of exocyclic substituent present (n-Bu vs Ph). Communication between the two phenanthrene or pyrene moieties was observed in some cases, which was characterized by bathochromically shifted emission bands relative to that of monomeric phenanthrene or pyrene species. Unique excited-state dimer (excimer) fluorescence was observed for the 2,2'-isomer 8, which was characterized by broad, low-energy emission bands bathochromically shifted from that of the corresponding monomer.

One-, two- and three-dimensional Cu(ii) complexes built via new oligopyrazinediamine ligands: from antiferromagnetic to ferromagnetic coupling

Six new pyrazine-modulated N,N'-bis(alpha-pyridyl)-2,6-diaminopyridine ligands (PMN5) were synthesized and their complexes studied. Reaction of copper(II) with the ligand that contained one pyrazine ring in its terminal position led to formation of a one-dimensional zigzag complex whereas copper(II) reactions with ligands containing three pyrazine rings or one pyrazine ring in its middle position yielded straight one-dimensional complexes. A 2-D complex was produced from the ligand with two pyrazine rings at both terminals. When nickel(II) was introduced, a 3-D network was obtained from the three-pyrazine-modulated ligand. Researches on variable-temperature magnetic susceptibility measurements revealed excellent Heisenberg chains with weak antiferromagnetic interaction of J values from -2 to -3 cm(-1)viasigma and pi pathways in straight one-dimensional complexes between the Cu(II) centers separated by 6.8-6.9 A. The zigzag one-dimensional complex showed very poor magnetic coupling. The two-dimensional compound showed significant ferromagnetic interaction in spite of the Cu-Cu distance of 7.2 A. Ferromagnetic coupling was discussed and attributed to the unusual coordination mode of in-plane and out-of-plane linkage of bridging pyrazine rings. The three-dimensional heterometal Cu(II)-Ni(II) compound showed weak antiferromagnetic interaction, which was satisfactorily fitted with J=-2.4 cm(-1) following a one-dimensional theoretical model including MFA.

The Isolation and Structure Elucidation of a New Sesquiterpene Lactone from the Poisonous Plant Coriaria japonica (Coriariaceae).

AbstractFor Abstract see ChemInform Abstract in Full Text.

Bismuth Borates: One‐Dimensional Borate Chains and Nonlinear Optical Properties.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Recent Development of a Porphyrin Mutant — N‐Confused Porphyrin

AbstractFor Abstract see ChemInform Abstract in Full Text.

Bismuth Borates: One-Dimensional Borate Chains and Nonlinear Optical Properties

Three bismuth borates, Bi[B4O6(OH)2]OH (I), BiB2O4F (II), and Bi3[B6O13(OH)] (III), were obtained in boric acid flux at low temperatures and their structures were determined by using single-crystal and powder X-ray diffraction techniques. All these three bismuth borates contain one-dimensional borate chains and crystallize in noncentrosymmetric space groups. I is a hydrated borate, crystallizing in the space group P1 with lattice constants a = 4.300(1) Å, b = 8.587(2) Å, c = 10.518(2) Å, α = 113.11(3)°, β = 100.50(3)°, and γ = 90.36(3)°, and the borate chain consists of a 3-ring (2BO3 + BO4) and a BO3 group. II is a fluoroborate, which crystallizes in the trigonal space group P32 with a = 6.7147(1) Å and c = 6.4688(1) Å, and the borate anion is a 3-fold helix chain formed by extensive linkage of three-membered borate rings (3BO4). III is also a hydrated borate with a structure that is closely related to II, in which one-sixth of the borate groups are in triangular geometry (BO3), which reduces the symmetry to P1, a = 6.6257(1) Å, b =6.6238(1) Å, c = 6.6541(1) Å, and α = 89.998(3)°, β = 89.982(2)°, and γ = 119.992(2)°. All these three bismuth borates exhibit nonlinear optical (NLO) properties.

ポルフィリン変異種―Ｎ‐混乱ポルフィリン―の最近の展開について

Unusual α and β' linkage of the pyrrole rings (confusion) in porphyrinoids affords a new family of porphyrin analogs having unique physical properties, reactivity and metal-coordination chemistry. Since the finding of N-confused porphyrin (NCP), an isomer of porphyrin, in 1994, various confused porphyrinoids and their metal complexes, including multiply N-confused, hetero-atom substituted, and ring expanded ones, have been synthesized, successively. Confused porphyrinoids reveal a lot of interesting properties, such as NH tautomerism, inner- and outer-metal coordination, organometallics nature, multiple redox system, extended aromatic π-system, etc. In this article, recent development of the confused porphyrinoids is summarized.

The Isolation and Structure Elucidation of a New Sesquiterpene Lactone from the Poisonous Plant Coriaria japonica (Coriariaceae)

A new sesquiterpene lactone named coriarin was isolated from achenes (seeds) of Coriaria japonica (Coriariaceae) along with known constituents tutin, dihydrotutin and corianin, and its structure was deduced on a spectroscopic basis. The structure of coriarin was finally confirmed by the base-catalized chemical conversion of tutin into coriarin, in which the lactone ring linkage was transposed from C-3 to C-2. Chemical investigation of sarcocarps was also undertaken in parallel, but neither sesquiterpene lactones nor related constituents were obtained. The results indicate that sesquiterpene lactones occur only in achenes of C. japonica berry, as is the case in other Coriaria species.