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Oxidation reactions of 1,2-diarylbenzenes induce intramolecular C-C bond formation. The substrates studied here were prepared by the stepwise Suzuki-Miyaura coupling reaction that introduced 2-naphthyl, 2-anthranyl, and 2-pyrenyl groups on the ortho positions of benzene. The subsequent oxidation reaction with FeCl3 induced an oxidative C-C bond formation reaction in the interior regions of the molecules. In marked contrast to our previous observations, two C-C bonds were formed. Theoretical calculations indicated that large spin densities at the reaction positions of the bis(cation radical) and/or cation radical species are needed for the C-C bond formation. The π-expanded molecules obtained here showed bathochromic shifts in the absorption spectra and amphoteric multi-redox behavior in electrochemistry.

Considering the widespread interest in the chiroptical properties of materials, especially circularly polarized luminescence (CPL), the functionalization of bipyrenol (BPy) was carried out aiming at future advanced chiral materials (ACMs) in which BPy shows a high quantum yield and clear CPL spectra. To create ACMs using BPy units that contain nucleophilic substituents, amine and thiol were selected as the functional group and attached to BPy by means of alkyl linkages. The obtained thiol and amine derivatives are stable under ambient conditions. To demonstrate the potential of these molecules, photoinduced electron-transfer systems were synthesized.

Treatments of dihydroxyporphyrinato Sn(IV) with 1- and 2-hydroxypyrenols afforded 1- and 2-hydroxypyrene-coordinated Sn(IV) porphyrins. Because of their stability, these complexes enable conventional chemical manipulations, such as SiO2 column chromatography. Single-crystal diffraction studies revealed that the dihedral angles between the porphyrin and the pyrenolato ligand are small. The large high-field shifts of 1H NMR signals attributable to the pyrenolato ligand support the parallel alignment of the porphyrin and the pyrenolato ligand. Singlet signals of the β-hydrogens of porphyrin suggest the free rotation of the pyrenolato ligand around the Sn-O coordination bond. In addition, low-field shifts were observed for these β-hydrogens. These phenomena suggest the free rotation of the pyrenolato ligand around the pyrenolato O-C bond. Because these two rotation axes are positioned at an angle of 120°, this moiety could be regarded to show the transmission-like motion in molecular machines.

The molecular structure of 9,10-bis[bis(4-tert-butylphenyl)methylene)-9,10-dihydroanthracene, an anthraquinodimethane derivative having four aryl groups on exocyclic methylene positions, was experimentally and theoretically characterized. Single-crystal diffraction study revealed that the title molecule takes a butterfly shape, i.e., two exocyclic carbons rise from the molecular plane, defined by four carbons of central quinoidal ring, by 1.257(3) A (average). The dihedral angle of the butterfly wing, i.e., the angle between the two annulated benzenes is 137.71(5)°. Characteristic bond alternation was observed for the central quinoidal moiety and the exocyclic double bond. Theoretical study indicated that this butterfly shape is the stable structure. The two optimized structures nearly reproduced the experimentally observed molecular structures, bond distances, and angles.

Quality of CPL fluorophore is defined by the vectors of electric dipole transition moment and imaginary magnetic dipole transition moment. The aim of this review is to introduce readers to a chiral moiety applicable to CPL studies focusing on chiral cyclophanes because the rigid cyclophanes are able to hold the vector directions of electric dipole transition moment and imaginary magnetic dipole transition moment.

An innovative π-expanded ligand derived from salicylaldimine ligand representing pyrene ring as a substitute for benzene ring was synthesized in 5 steps from commercially available pyrene. This unique bidentate ligand (1) was coordinated to Cu(II) metal centre for affording complex 2, which was characterized by IR, elemental, X-ray diffraction analyses, and magnetic susceptibility. Its coordination geometry is a trans-square plane with an obvious stair-step structure which is formed by two pyrene moieties and the coordination plane (CuN2O2). In addition, the dihedral angle between the coordination plane and the pyrene ring is 34.9o and the plane of seven carbon atoms of the long alkyl chains were arranged nearly parallel to the pyrene rings. The electronic properties of this novel complex 2 were examined via cyclic voltammetry and absorption spectroscopy to show the narrower HOMO-LUMO gap than those of the complex 4. Moreover, the particular behavior of both complexes 2 and 4 was investigated through DFT studies.

Unsymmetrically substituted biphenoquinones, 3,5-dimethyl-3′,5′-diphenylbiphenoquinone and 3,5-di-tert-butyl-3′,5′-diphenylbiphenoquinone, were prepared by a mixed oxidative coupling reaction of the corresponding phenols with potassium permanganate in CHCl3. The properties of the quinones such as reduction potential and visible light absorption were measured and positively shifted reduction potentials and bathochromic shifts as a result of light absorption were found to be characteristic of the π-expanded quinones. We also carried out single-crystal diffraction study and uncovered a unique packing motif attributable to their unsymmetrical structures.

Six-coordinated tungsten(VI) complexes with one rigid chiral bidentate ligand, 1,1′-bi-2-naphthol (bino) 1, and two flexible bidentate ligands (f-bls), pinacol (pin) or ethylene glycol (en), were prepared, and their stereochemistry was discussed. Generally, metal complexes with three f-bls produce enantiomeric Δ- and Λ-forms. Other types of isomerism are produced by f-bls, which are attributable to their conformation, i.e., δ- and λ-forms. Although the conformational isomerism of Δ- and Λ-enantiomers produces diastereomers, the energy differences between the diastereomers are small, less than several kcal mol−1. Therefore, the conformational isomerism of f-bls is not significant in coordination chemistry. We found that the introduction of one rigid chiral bidentate ligand controls the Δ- and Λ-stereochemistry of the complex. The conformation of (R)-bino produces the Δ-isomer, and that of (S)-bino affords the Λ-isomer. We also performed theoretical studies to support our observations.

Tetra(thienyl)biphenoquinones were designed and synthesized. An oxidative coupling of 2,6-bis(3-thienyl)phenol with PbO2 in acetic acid afforded the corresponding biphenoquinone along with 2,6-bis(3-thienyl)-p-benzoquinone. This biphenoquinone showed properties characteristic of a pai-expanded quinone, i.e., positively shifted reduction potential and light absorption in the visible region. In contrast to kinetically protected biphenoquinones having bulky substituents at the ortho-positions of carbonyls, the title compounds take a planar structure because of the small steric repulsion of the five-membered thiophene rings. Its charge transfer complex with perylene is characterized by a well-overlapped mixed stack.

An alternative synthesis has been developed with the objective of extending the applications of bipyrenol in mind. The key reaction involves the oxidative coupling of 2-hydroxypyrene menthyl carbonate to afford the corresponding pyrene dimer. In marked contrast to our previous method, i.e., the oxidation of 2-hydroxypyrene, the revised method is a clean and high-yielding reaction. By optimizing the reaction conditions, the yield of the alternative synthesis is increased to 88%.

The Suzuki–Miyaura coupling reaction of pyren-2-yl boronic acid ester with a meso-dibromodiphenylporphyrin derivative was carried out to give another pyrene-substituted porphyrin. The electrophilic substitution reaction occurred selectively on the porphyrin nucleus of this molecule. The introduced pyrenes acted as a light-harvesting antenna.

The reactions of Co(OAc)2 with two equivalents of 1-hydroxy-2-[(octylimino)methyl-pyrene L, performed in air, lead to the formation of the cobalt(III) complex, tris[2-[(octylimino)methyl]-1-pyrenolato-N,O] cobalt(III) CoL3, accommodating three chelating pyrene-based salicylaldiminato-type ligands. The complex CoL3 and the referent tris(salicylaldiminato) cobalt(III) 1’(CoIII) were obtained in excellent yields, and their characterisation by 1H NMR, IR, mass spectroscopy, elemental analysis and X-ray diffraction revealed that they were of diamagnetic nature, octahedral geometry with the cobalt centre and meridional configuration. The redox behaviour of these complexes shows an irreversible reduction wave with a peak potential in the range -1.9 to -1.2 V. Upon reduction, the complexes decompose, giving rise to a redox pattern compatible with the formation of bis[2-[(octylimino)methyl]-1-pyrenolato-N,O] cobalt(II). Keywords: Coordination chemistry, Cobalt, Pyrene, π-Expanded ligand, Salicylaldimine. References: [1] Luong Xuan Dien, Ken-ichi Yamashita, Motoko S. Asano, Ken-ichi Sugiura, Synthesis of a pyrene-based π-expanded ligand and the corresponding platinum(II) complex, Bis[2-[(octylimino)methyl]-1-pyrenolato-N,O] platinum(II), Inorganica Chimica Acta, 432 (2015) 103-108. https://doi.org/10.1016/j.ica. 2015.03.038.[2] Luong Xuan Dien, Ken-ichi Yamashita, Ken-ichi Sugiura, Metal Complexes of π-Expanded Ligands (2): Synthesis and characterizations of bis[2-[(octylimino)methyl]-1-pyrenolato-N,O] palladium(II) and the stabilized vacant dx2-y2 orbital, Polyhedron, 102 (2015) 69-74. https://doi.org/10.1016/j.poly.2015.07.043.[3] Luong Xuan Dien, Nguyen Xuan Truong, Ngo Duc Quan, Ken-ichi Yamashita, Ken-ichi Sugiura, Syntheses and structures of Ni(II) complexes containing 2 alkyliminomethyl pyrene ligands, VNU Journal of Science, 34 (4) (2018) 16-20. https://doi.org/10.25073/2588-1140/vnunst.4809.[4] Robert D. Jones, David A. Summerville, Fred. Basolo, Synthetic oxygen carriers related to biological systems, Chem. Rev., 79 (1979) 139-179. https://doi.org/10.1021/cr60318a002.[5] Kuninobu Kasuga, Takeo Nagahara, Akira Tsuge, Kunihisa Sogabe, Yasuo Yamamoto, The preparation and some properties of cobalt(II) schiff base complexes and their molecular oxygen adducts, Bull. Chem. Soc. Jpn., 56 (1983) 95-98. https://doi.org/10.1246/bcsj.56.95.[6] H. Pellissier, H. Clavier, Enantioselective cobalt-catalyzed transformations, Chem. Rev., 114 (2014) 2775-2823. https://doi.org/10.1021/ cr4004055.[7] R. H. Crabtree, Energy Production and Storage: Inorganic Chemical Strategies for a Warming World, first ed., John Wiley & Sons, West Sussex, 2010.[8] P. Sravanthi, C. Chandrakala, KS. Nagaraja, B. Jeyaraj, Development of cobalt Schiff base precursors for nanocrystalline cobalt oxide thin film by thermal CVD method, International journal of pharmaceutical, chemical and biological sciences, 5(1) (2015) 112-125. http:/ /www.ijpcbs.com/files/volume5-1-2015/12.pdf.[9] B. O. West, Complexes of tervalent cobalt with N-substituted salicylideneimines, J. Chem. Soc., 0 (1960) 4944-4947. https://doi.org/10. 1039/JR9600004944.[10] A. Ourari, Y. Ouennoughi, S. Bouacida, Tris(2-{[2-(4-meth¬oxy¬phen¬yl)eth¬yl]imino-meth¬yl}phenolato-κ2N,O1)cobalt(III), Acta Cryst., E68 (2012) m803-m804. https://doi.org/10.1107/ S1600536812023033.[11] A. Chakravorty , R. H. Holm, Identification of the geometrical isomers of some tris-chelate cobalt(III) complexes by nuclear resonance, Inorg. Chem., 3 (1964) 1521-1524. https://doi. org/10.1021/ic50021a010.[12] S. Li, S.-B. Wang, K. Tang, Y.-F. Ma, Tris [2-(propyliminomethyl)phenolato-κ2 N,O]cobalt(III), Acta Cryst., E64 (2008) m823. https://doi.org/ 10.1107/S1600536808014074.

A facile and metal-free method for the preparation of free base meso-aminodiarylporphyrins from readily available meso-bromodiarylporphyrins is described. Simple treatment of meso-bromoporphyrins with sodium azide and sodium ascorbate in DMF affords the corresponding meso-aminoporphyrins in very good yields. This method involves the aromatic nucleophilic substitution (SNAr) of a bromo group with an azido group and the subsequent in situ reduction of the introduced azido group by sodium ascorbate. This amination reaction can be scaled up to gram scale without any decrease of the product yield. The amination reaction of free base meso-dibromoporphyrin affords a monoaminated product selectively, whereas that of the Ni(II) complex furnishes a diaminated product that is oxidized by air under ambient conditions but isolable as a trifluoroacetyl ester. Metal-insertion reactions of the obtained free base aminoporphyrins afford the corresponding metal complexes (Ni(II), Cu(II), Zn(II), and Pd(II)) all in good yiel...

Based on our recent reinvestigation of the disproportionation reaction of 3,3′,5,5′-tetraphenyl-4,4′-biphenoquinone, which exhibited drastic color change, we performed the synthesis and characterization of 3,3′′,5,5′′-tetraphenyl-4,4′′-terphenoquinone with the aim of obtaining enhanced physical properties, such as lower reduction potentials and bathochromic shift in light absorption, and realizing a disproportionation reaction at a lower temperature. To construct the terphenyl and/or terphenoquinone skeletons, the Suzuki-Miyaura coupling, which involves coupling between 1,4-diiodobenzene and the boronic acid ester with phenyl and oxygen moieties attached was carried out. The subsequent hydroquinone formation reaction and oxidation reaction yielded a brilliant ultramarine-blue terphenoquinone. The quinone showed properties typical of π-expanded quinones, namely, positively shifted reduction potential, small on-site Coulomb repulsion, and lower excitation energy. DSC measurement of this product showed an exothermic process at 212.5 °C and this temperature was much lower than that of the corresponding biphenoquinone, 289.5 °C. The products of this reaction were similar to those of the biphenoquinone reaction, i. e., two benzofurans and the corresponding hydroquinone.

The Glaser–Hay coupling reaction of a tetraphenylporphyrin derivative having two acetylenes in the quasi-trans positions was carried out. Although this oxidative coupling reaction has high reactivity and produces various butadiynylene oligomers, the degree of oligo­merization was low. A large substrate and/or product might decrease the frequency factor of the Arrhenius equation and the resultant rate constant. This finding is in agreement with that of the one-pot synthesis of structurally well-defined porphyrin oligomers, such as trimers and tetramers, which are used frequently in the field of advanced materials.

Oxo(porphyrinato)vanadium(IV), the oxovanadium [V IV O] 2+ complex of unsubstituted porphyrin, was prepared and structurally characterized. Our synthetic method enabled us to obtain 1 in sufficient quantity. The paramagnetic complex was characterized by IR and mass spectroscopic measurements. The IR spectrum contained a strong absorption at 994 cm −1 (in KBr matrix) attributable to the V O stretching mode. Single-crystal diffraction study revealed that 1 was a pot lid shaped molecule, i.e. , 1 exhibited a five-coordinate pseudo -square pyramidal geometry at the vanadium center. Vanadium was located above the porphyrin mean plane with a distance of 0.537(1) A, and an oxygen atom was coordinated perpendicularly with a bond distance of 1.599(2) A. The ligation of electropositive [V IV O] 2+ induced a partial negative charge on N and a positive charge on vanadium. The resultant polarization induced an electrostatic attractive interaction, affording a dimer in the solid state with a very short interplanar distance of 3.269(2) A. This dimer unit was packed in a herringbone manner.

A pyrene-based new ligand (1) attaching hydroxyl and imine group, i.e., a salicylaldimine-style ligand based on pyrene, was designed and synthesized. The ligand was prepared from the commercially available pyrene in five steps. A treatment of this ligand 1 (L) with Pt(II)Cl2(PhCN)2 in the presence of AcONa in PhCl afforded the corresponding metal complex, Pt(II)L2 (2) (80%). Single crystal diffraction study revealed that the complex is a square planar four-coordinated platinum(II) complex. The ligands bind to the metal in trans-manner. The coordination geometry, i.e., bond distances and angles for the coordination site, is the typical of the reported platinum(II) salicylaldiminatos, e.g., the mean Pt–N distance (d(Pt–N)): 2.011 and d(Pt–O): 1.994 A, respectively. The expansion of the π-system of the ligand induces the bathochromic shift in absorption spectra. The lowest excitation energy of 2 was found at 520 nm. Theoretical studies suggest that this phenomenon is attributable to the narrowing intramolecular HOMO–LUMO gap of 2.

A push–pull porphyrin dimer with multiple electron-donating groups has been synthesized as a sensitizer with an excellent light-harvesting ability in the near-infrared region for dye-sensitized solar cells (DSSCs). The DSSC based on the sensitizer exhibited the photocurrent generation exceeding a wavelength of 900 nm, together with a power conversion efficiency of 6.21% under AM 1.5 condition.

We studied the conductance of Au/1,4-benzenedicarbothioamide (BDTA)/Au junctions at room temperature and measured a single-molecule conductance of BDTA. A carbothioamide (thioamide, – CSNH 2 ) group of this molecule consists of two potential linkers, thioketone and amine groups, and would thus be expected to show high conductance. The experimental single-molecule conductance of BDTA is ( 0.8 – 1.0 ) × 10 - 3 G 0 which roughly compares with that of π -conjugated molecules. We consider that this relatively high conductance of Au/BDTA/Au is due to the homoconjugation of π -orbitals of benzene and sulfur while the amine group is likely to remain as a side group. We also observed that Au/BDTA/Au junctions can exist in multiple configurations of different conductances.

Visible light irradiation of anthracene in the presence of platinum(II) porphyrin (PtPor) and dioxygen affords anthraquinone as the main product. This reaction involves two steps: the [4+2]cycloaddition of anthracene with singlet oxygen to afford anthracene-9,10-endoperoxide and the degradation of endoperoxide. PtPor catalyzes both reactions.

Axially chiral biaryls based on pyrene, 1,1′-bipyrene-2,2′-diol derivatives 2, were designed and synthesized from 2-hydroxypyrene. Simple optical resolution was carried out and the absolute configu...

A series of structurally well-defined molecular wires were designed and synthesized. The wires consisted of metalloporphyrins connected by platinum acetylides. Stepwise synthesis afforded stable wi...

A facile and mild method for the preparation of platinum(II) porphyrin complexes is reported. A simple treatment of free-base porphyrins with 1.5 equiv of [PtCl2(PhCN)2] in the presence of sodium p...

LEC-1 is a major galectin in Caenorhabditis elegans and contains two carbohydrate recognition domains (CRDs), N-CRD and C-CRD. To determine the role of LEC-1, we examined the phenotypes of a mutant C. elegans strain lacking lec-1. We observed negligible differences in embryogenesis, morphogenesis and egg laying at 20 °C between the mutant and the wild-type. Furthermore, the life spans of the mutant and the wild-type were equivalent at either 20 °C or 25 °C. However, the lec-1 mutant showed a greater susceptibility to H2O2 and paraquat than the wild-type. This result suggests an increased susceptibility to oxidative stress, with the phenotypes being similar to those of lec-10 deletion mutants as previously described. To understand the molecular mechanism underlying this phenotype, C. elegans proteins bound by either the LEC-1 N-CRD or C-CRD were isolated and identified using a nano liquid chromatography-tandem mass spectrometry technique. MIG-6 was identified as a major binding partner of LEC-1 with both N- and C-CRD. From these results and previous reports, we speculate that interaction of LEC-1 and MIG-6 in the pharynx may affect susceptibility to paraquat and that LEC-10 has different functions from LEC-1 in regulating H2O2 and paraquat resistance in the intestine.

meso-Mono- or diazidoporphyrins were readily obtained in high yields by the catalyst-free aromatic nucleophilic reaction of the corresponding bromoporphyrins with azide anions under mild conditions. The molecular structures of the obtained azides were unambiguously determined by X-ray crystallographic analysis.

In this communication, we report the superior role of 1,3-dimethyl-2-imidazolidinone (DMI) as a solvent for aromatic Finkelstein iodination (AFI), the conversion of aryl bromides to aryl iodides. DMI accelerates the reaction rate and affords product(s) that could not be prepared using previous methods. Our findings for AFI avoid the use of toxic solvents such as N,N-dimethylformamide and hexamethylphosphoramide.

The authors propose 4-alkoxy-3,5-diisopropyl-phenyl (DIPP) group as the most suitable substituent to realize porphyrin based advanced materials (PAMs). Our experiments reveal that DIPP achieved the introduction of the following properties on porphine and/or PAMs: (1) easy synthesis, (2) high solubility, (3) good crystallinity natures, and (4) single molecule visualization by scanning tunneling microscopy.

Galβ1-4GlcNAc is thought to be a common disaccharide unit preferentially recognized by vertebrate galectins. Eight amino acid residues conserved in proteins belonging to the galectin family have been suggested to be responsible for recognition. Meanwhile, we isolated and analyzed endogenous N-glycans of Caenorhabditis elegans that were captured by a C. elegans galectin LEC-6, and demonstrated that the unit of recognition for LEC-6 is a Gal-Fuc disaccharide, though the linkage between these residues was not confirmed. In the present study, we chemically synthesized Galβ1-4Fuc and Galβ1-3Fuc labeled with 2-aminopyridine (PA), and demonstrated that LEC-6 interacts with PA-Galβ1-4Fuc more strongly than PA-Galβ1-3Fuc by frontal affinity chromatography (FAC). Galβ1-4Fuc also inhibited hemagglutination caused by LEC-6 more strongly than Galβ1-3Fuc. FAC analysis using LEC-6 point mutants revealed that some of the conserved amino acid residues which have proved to be important for recognition of Galβ1-4GlcNAc are not necessary for the binding to Galβ1-4Fuc. Another major C. elegans galectin, LEC-1, also showed preferential binding toGalβ1-4Fuc. These results suggest that Galβ1-4Fuc is the endogenous unit structure recognized by C. elegans galectins, which implies that C. elegans glycans and galectins may have co-evolved through an alteration in the structures of C. elegans glycans and a subsequent conversion in the sugar-binding mechanism of galectins. Furthermore, since glycans containing the Galβ1-4Fuc disaccharide unit have been found in organisms belonging to 4 Protostomia, this unit might be a common glyco-epitope recognized by galectins in these organisms., DOI: 10.1093/glycob/cwp125 竹内智春(Takeuchi, Tomoharu)： 2010.4～ 城西大学（Josai University）薬学部薬学科分子免疫学講座

Control of the molecular orientation of double-decker complexes comprised of rare-earth metals sandwiched with naphthalocyanine and porphyrin/phthalocyanine, at the interface of a graphite surface and 1-phenyloctane solution, has been demonstrated for the future application of molecular rotor assembly. Scanning tunneling microscope images clarified the internal structures of the top ligands. The observed images indicate that naphthalocyanine ligands were selectively adsorbed onto the graphite surface and the counterpart ligands of porphyrin/phthalocyanine were oriented off the surface. Control of the orientation of monolayers of mixed double-decker complexes has also been demonstrated.

An alternated 1:1 chain compound of a Mn(III) salen derivative and the TCNQ monoradical was synthesized: [Mn(5-TMAMsaltmen)(TCNQ)](ClO(4))(2) (1) (TCNQ=tetracyano-p-quinodimethane; 5-TMAMsaltmen=N,N'-(1,1,2,2-tetramethylethylene) bis(5-trimethylammoniomethylsalicylideneiminato)). Compound 1 has a zigzag chain structure packed with adjacent chains with an interchain MnMn distance of over 8 Angatrom. As compound 1 contains no crystallization solvent, the void spaces between chains are occupied only by ClO(4) (-) counter ions. Compound 1 has a structure reminiscent of what has been observed in the family of Mn(III)(porphyrin)-TCNE or -TCNQ compounds reported previously by Miller and co-workers and we demonstrate herein its unique single-chain magnet behavior among this family of compounds. The direct current (dc) magnetic measurements established the one-dimensional nature of compound 1 with an antiferromagnetic exchange coupling, J/k(B) approximately -96 K, between the Mn(III) ion and TCNQ radical and with an activated correlation length (Delta(xi)=26.5 K) at low temperatures (50-15 K). The slow relaxation of the magnetization was shown in compound 1 by the field hysteresis of the magnetization observed below 3.5 K (with a coercive field up to 14 kOe at 1.8 K). Single-crystal magnetization measurements demonstrated the uniaxial symmetry of this compound and allowed an estimation of the anisotropy field, H(a) approximately 97 kOe. The absence of magnetic ordered phase or spin-glass behavior was established by heat-capacity calorimetry measurements that exhibit no abnormality of C(p) between 0.5 K and 10 K. The study of the magnetization relaxation by combined ac (alternating current) and dc techniques showed that compound 1 possesses a single relaxation time (tau). As the consequence of the finite size of the chain, the temperature dependence of tau presents two activated regimes above and below 4.5 K with tau(01)=2.1 x 10(-10) s, Delta(tau1)=94.1 K and tau(02)=6.8 x 10(-8) s and Delta(tau2)=67.7 K, respectively. The detailed analysis of these dynamics properties together with the correlation length, allows an unambiguous demonstration of the single-chain magnet behavior in 1.

A new class of mononuclear metal complexes with 1-methylimidazole-2-aldoximate (miao) has been synthesized and characterized: trans-NiII(Cl)2(Hmiao)2 (1), trans-NiII(miao)2(py)2 (2), NO-trans-NiII(miao)2(phen) (3), and NO-trans-FeII(miao)2(phen) (4). The crystal structures of 2, 3, and 4 have been determined by single-crystal X-ray crystallography. Compound 1 having the protonated miao ligand (i.e., Hmiao) is a precursor for synthesizing 2 and 3. Compound 2 is an octahedral NiII complex surrounded by two miao bidentate ligands and two monodentate ligands of pyridine in a trans-arrangement. Compound 3 is a cis-type octahedral NiII complex with two miao ligands and a bidentate ligand of 1,10-phenanthroline, in which the ligand arrangement around NiII center is found in an NO-trans form. Compound 4 is an isostructural FeII derivative of 3. Compounds 1, 2, and 3 exhibit paramagnetic nature with an S = 1 spin and a positive zero-field splitting, among which it for 3 is overlapped with intermolecular ferromagnetic interaction (zJ/kB = +0.16 K). Compound 4 is diamagnetic due to the existence of low-spin FeII ion.

Mn I I I -Ni I I -Mn I I I linear-type trinuclear complexes bridged by oximate groups were selectively synthesized by the assembly reaction of [Mn 2 (5-Rsaltmen) 2 (H 2 O) 2 ](ClO 4 ) 2 (5-Rsaltmen 2 - = N,N'-(1,1,2,2-tetramethylethylene) bis(5-R-salicylideneiminate); R=Cl, Br) with [Ni(pao) 2 (phen)] (pao - = pyridine-2-aldoximate; phen = 1,10-phenanthroline) in methanol/ water: [Mn 2 (5-Rsaltmen) 2 Ni(pao) 2 -(phen)](ClO 4 ) 2 (R=Cl, 1; R=Br, 2). Structural analysis revealed that the [Mn I I I -ON-Ni I I -NO-Mn I I I ] skeleton of these trimers is in every respect similar to the repeating unit found in the previously reported series of 1D materials [Mn 2 (saltmen) 2 Ni(pao) 2 (L 1 ) 2 ](A) 2 (L 1 = pyridine, 4-picoline, 4-tert-butylpyridine, N-methylimidazole; A = ClO 4 - , BF 4 - , PF 6 - , ReO 4 - ). Recently, these 1D compounds have attracted a great deal of attention for their magnetic properties, since they exhibit slow relaxation of the magnetization (also called single-chain magnet (SCM) behavior). This unique magnetic behavior was explained in the framework of Glauber's theory, generalized for chains of ferromagnetically coupled anisotropic spins. Thus, in these 1D compounds, the [Mn I I I -ON-Ni I I -NO-Mn I I I ] unit was considered as an S T =3 anisotropic spin. Direct-current magnetic measurements on 1 and 2 confirm their S T =3 ground state and strong uniaxial anisotropy (D/k B -2.4 K), in excellent agreement with the magnetic characteristic deduced in the study on the SCM series. The ac magnetic susceptibility of these trimers is strongly frequency-dependent and characteristic of single-molecule magnet (SMM) behavior. The relaxation time r shows a thermally activated (Arrhenius) behavior with τ 0 1×10 - 7 s and Δ e f f /k B 18 K. The effective energy barrier for reversal of the magnetization Δ e f f is consistent with the theoretical value (21 K) estimated from ‖D‖S 2 T . The present results reinforce consistently the interpretation of the SCM behavior observed in the [Mn 2 (saltmen) 2 Ni-(pao) 2 (L 1 ) 2 ](A) 2 series and opens new perspectives to design single-chain magnets.

The selective meso-monobromination of 5,15-diarylporphyrins is difficult to achieve and extensive chromatography is required to obtain pure products. A sequence of (i) dibromination, (ii) selective monoinsertion of Pd ( dppe ) (dppe = 1,2-bis(diphenylphosphino)ethane) and (iii) hydrodepalladation using methanolic base affords pure monobromoporphyrins in typically ≥ 60% overall yield without isolation of the organopalladium porphyrin. Monobromo derivatives of even highly lipophilic 5,15-diarylporphyrins are thus readily available without tedious, expensive and environmentally undesirable chromatography.

Two Ni(II) pyridine-2-aldoximate complexes, Ni(pao)2(bpy) (1) and Ni(pao)2(phen) (2) (pao−=pyridine-2-aldoximate, bpy=2,2′-bipyridine, phen=1,10-phenanthroline), were synthesized via the deprotonation of NiCl2(Hpao)2 in methanol followed by the addition of bidentate ligands of 2,2′-bipyridine and 1,10-phenanthroline. Crystallization in CHCl3 gave block-type crystals of 1 and 2 in high yields. The mononuclear structure surrounded by three bidentate ligands, i.e., two pao− and one bpy or phen, was revealed by X-ray crystallography: 1 crystallizes in monoclinic space group P21/c with cell dimensions of a=13.457(3) A, b=14.493(3) A, c=19.104(4) A, β=108.681(3)°, Z=4, and 2 crystallizes in monoclinic space group P21/n with cell dimensions of a=14.235(5) A, b=12.018(4) A, c=20.696(7) A, β=110.304(4)°, Z=4. 1 and 2 each have two oximate groups (pao−), with an NO-trans arrangement around the NiII ion. Complexes 1 and 2 are racemic, namely, each molecule has a chiral center of Δ or Λ, thereby forming NO-trans-Δ and -Λ geometries in the solid state. Magnetic measurements revealed a paramagnetic S=1 spin state with a positive zero-field splitting parameter.

A series of single-chain magnets, [Mn2(saltmen)2Ni(pao)2(L)2](A)2 (saltmen(2-)=N,N'-(1,1,2,2-tetramethylethylene) bis(salicylideneiminate), pao-=pyridine-2-aldoximate; A-=ClO4- with L=4-picoline; 2, 4-tert-butylpyridine; 3, N-methylimidazole; 4, and L=pyridine with A-=BF4-; 5, PF6-; 6, ReO4-; 7), was prepared by reactions between MnIII dimer units, i.e., [Mn2(saltmen)2(H2O)2](A)2 (A-=ClO4-, BF4-, PF6-) or Mn2(saltmen)2(ReO4)2, and NiII monomeric units, i.e., Ni(pao)2(L)2, in methanol/water media. The crystal structures of 4, 6, and 7 were established by single-crystal X-ray crystallography. These three compounds are isostructural with [Mn2(saltmen)2Ni(pao)2(py)2](ClO4)2 (1) (Clerac, R.; Miyasaka, H.; Yamashita, M.; Coulon, C. J. Am. Chem. Soc. 2002, 124, 12837) and crystallize in monoclinic space group C2/c. The linear arrangement of MnIII dimer units and NiII building blocks leads to an alternating chain having a repeating unit, [-(O)2-Mn-ON-Ni-NO-Mn-]. The chains are well separated with the nearest interchain intermetallic distance of 10.36 A for 4, 10.51 A for 6, and 10.30 A for 7, and there is no significant pi-pi interchain interaction between ligands. The void space between the chains is occupied by counteranions, which control the three-dimensional organization of the chains. The X-ray diffraction analysis (XRD) on a powder sample was also performed for all compounds. The XRD patterns for 1, 2, and 4-7 are very similar, emphasizing the isostructural nature of these materials although they have individually slight different interchain distances. Inversely, the XRD pattern for 3 reveals a completely different shape being indicative of the peculiar crystal packing compared to the others. Nevertheless, the one-dimensional nature of the structure is also kept in 3 as indicated by magnetic measurements. The whole family of compounds exhibits quasi-identical magnetic behavior compared to that described for 1. Above 30 K, the heterometallic chain can be described as an assembly of antiferromagnetically coupled Mn...Ni....Mn trimers (via oximate bridge, -24.2 K

A substituted porphyrinatoplatinum(II), meso-tetrakis(4-t-butylphenyl)porphyrinatoplatinum(II), has been spectroscopically and structurally characterized. The 1H NMR signal from the β-protons of the pyrrole ring is observed as a singlet with a full-width at half maximum of 1.6 Hz, contrary to the reported quasi-triplet resonance attributable to the 1H–195Pt long-range coupling. The porphyrin nucleus is nearly planar in the solid state. All macrocycle atoms lie within approximately 0.06 A of the least squares mean plane with a pseudo-wave core conformation. The intramolecular Pt–N distances are 2.019(3) A.

The title compound, (NEt(4))[[Mn(salen)](2)Fe(CN)(6)] (1), was synthesized via a 1:1 reaction of [Mn(salen)(H(2)O)]ClO(4) with (NEt(4))(3)[Fe(CN)(6)] in a methanol/ethanol medium (NEt(4)(+) = tetraethylammonium cation, salen(2)(-) = N,N'-ethylenebis(salicylidene)iminate). The two-dimensional layered structure of 1 was revealed by X-ray crystallographic analysis: 1 crystallizes in monoclinic space group P2(1)/c with cell dimensions of a = 12.3660(8) A, b = 15.311(1) A, c = 12.918(1) A, beta = 110.971(4) degrees, Z = 2 and is isostructural to the previously synthesized compound, (NEt(4))[[Mn(5-Clsalen)](2)Fe(CN)(6)] (5-Clsalen(2-) = N,N'-ethylenebis(5-chlorosalicylidene)iminate; Miyasaka, H.; Matsumoto, N.; Re, N.; Gallo, E.; Floriani, C. Inorg. Chem. 1997, 36, 670). The Mn ion is surrounded by an equatorial salen quadridentate ligand and two axial nitrogen atoms from the [Fe(CN)(6)](3-) unit, the four Fe[bond]CN groups of which coordinate to the Mn ions of [Mn(salen)](+) units, forming a two-dimensional network having [[bond]Mn[bond]NC[bond]Fe[bond]CN[bond]](4) cyclic repeating units. The network is spread over the bc-plane of the unit cell, and the layers are stacked along the a-axis. The countercation NEt(4)(+) is located between the layers. Compound 1 is a ferrimagnet with T(c) = 7.7 K and exhibits hysteresis with a remnant magnetization of 13.44 cm(3).mol(-1) (M/N mu(B) = 2.4) at zero field and a coercivity of 1000 Oe when the powder sample was measured at 1.9 K. Magnetic measurements of a direction-arranged single crystal were also carried out. The orientation of the crystallographic axes of a selected single crystal was determined by X-ray analysis, and magnetization was measured when an external field was applied in the a*, b, and c directions. The magnetization in the a* direction increased more easily than those in the b and c directions below the critical temperature. No hysteresis was observed only for the measurement in the a* direction, indicating the presence of strong structural anisotropy with potential anisotropy on Mn(III) ions.

A series of 2,3,7,8,12,13,17,18-octakis(alkyl-thio)tetraazaporphyrins (H2OATTAP) with different alkyl chain lengths have been synthesized. Cyclic voltammetry and differential pulse voltammetry have been used to investigate the effect of the controlled lengths of the eight peripheral thioether tails on the redox behavior of the molecules. The electrochemical reduction of octakis(hexyl-thio)tetraazaporphyrins, MOHTTAP (where M = Cu , Ni ), was studied in 1,2-dichloroethane at a platinum electrode. The Cu derivative was oxidized in one single-electron-transfer step to yield a π-cation radical and reduced in three single-electron-transfer steps to yield a π-anion radical, dianion and trianion, respectively. For the Ni derivative, electron transfer reactions involving both the central metal atom and the macrocyclic ring were observed. Electron transfer pathways are proposed based upon voltammetric and in situ spectroelectrochemical results.

The cocrystallites that contain C 60 , C 70 and endohedral metallofullerenes with metal complexes of macrocycles are reviewed. Metal complexes of porphyrin cocrystallites with fullerenes form solids with remarkably close contact between the curved π surface of a fullerene and the planar π surface of a porphyrin, without the need for matching convex with concave surfaces. The structures of metal octaethylporphyrins (oeps) in C 60 ·Pd(II)(oep)·1.5C 6 H 6 , C 60 ·Cu(II)(oep)·2C 6 H 6 , C 60 ·Ag(II)(oep)·2C 6 H 6 and C 60 ·2Ni(II)(oep)·2C 6 H 5 Cl reveal the remarkable anti -formed oep configurations, with the four ethyl groups of the metal oep portions lying on both the same and the opposite sides of the porphyrin plane toward the C 60 . On the other hand, syn -formed metal oeps are observed in the many cases of metal oep compounds, suggesting that there is a face-to-face interaction between two adjacent oep planes. A new cocrystallite which exhibits a strong intermolecular interaction between fullerene C 60 and the Co(tbp) is also reviewed, where tbp denotes a dianion of tetra(bis- tert -butylphenyl)porphyrin. The intermolecular interactions of the anti - and syn -formed metal oeps in the cocrystallites containing fullerenes are also described by DV-Xα molecular orbital calculation.

Three Mn(III) quadridentate Schiff base compounds with N , N '-(1, 1, 2, 2-tetramethylethylene)bis(5-chlorosalicylideneiminato) (5-Clsaltmen 2 m ) were prepared and characterized: [Mn 2 (5-Clsaltmen) 2 (H 2 O) 2 ](ClO 4 ) 2 ( 1 ), [Mn 2 (5-Clsaltmen) 2 (5-Clsal) 2 ](ClO 4 ) 2 ( 2 ; 5-Clsal=5-chlorosalicylaldehydonato), and [NEt 4 ] 2 [Mn 2 (5-Clsaltmen) 2 (MeOH) 2 ][Fe(CN) 6 ]ClO 4 ·2MeOH ( 3 . All compounds contain Mn(III) out-of-plane dimer units. The magnetic measurements revealed intra-dimer ferromagnetic exchange interaction between Mn(III) ions via phenolate oxygen, producing a S =4 spin ground state. Mn(III) quadridentate Schiff base compounds out-of-plane dimers ferromagnetic interaction S =4 spin ground state

The reactions of Mn(III) quadridentate Schiff base compounds, [Mn(saltmen)(H 2 O)]ClO 4 ( 1 ; saltmen 2 m = N , N '-(1, 1, 2, 2-tetramethylethylene)bis(salicylideneiminato)) and [Mn(naphtmen)(H 2 O...

The addition of 0.5 equiv of vinylboronic acid pinacol ester I to 1-bromopyrene derivative 3 in the presence of [Pd(PPh3)4] and K2CO3 induced a cascade reaction involving Suzuki–Miyaura and Mizorok...