Papers - Yoshioka, Naoki

Synthesis and Structures of Vanadium-Cerium Trinuclear Complexes with Schiff-Base Ligands

TSUCHIMOTO MASANOBU, ISHII TOSHIO, IMAOKA TAKANE, YAMAMOTO KIMIHISA, YOSHIOKA NAOKI, SUNATSUKI YUKINARI

Bulletin of the Chemical Society of Japan (CHEMICAL SOC JAPAN)  79 ( 9 ) 1393 - 1397 2006.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0009-2673

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A vanadium(V)-cerium(IV) trinuclear complex, [{(VO2)-O-V(L-1)}(2)Ce-IV](1) (H3L1: N,N'-bis-3-ethoxysalicylidene-2-hydroxy-1,3-propanediamine),was prepared by the reaction of [(VO)-O-IV(acac)(2)] and [Ce-III(acac)(3)](.)3H(2)O with H3L1 in CH3CN, followed by oxidation of the product in air. The structure of complex 1 was determined by X-ray
crystal structure analysis. The complex has a V-V-Ce-IV-V-V trinuclear structure with two dioxovanadium(V) moieties on each side of the cerium(IV) moiety. Complex I has two L-1 ligands to form a trinuclear structure. The basal oxo atoms of the dioxovanadium(V) moieties are coordinated to the cerium atom with Ce-O distances of 2.322(3) and 2.343(3) angstrom. The apical two non-coordinating oxo atoms are
oriented to the same direction to form an endo structure. IR data of complex 1 show V=O stretching bands at 975 cm(-1) for the apical non-coordinated oxo atoms and 802 cm(-1) for the basal coordinated oxo atoms. The cyclic voltammogram of complex I in CH3CN shows a quasi-reversible two-electron redox couple with E-1/2 = -0.60 V vs Fc/Fc(+).

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DNA-Binding Properties and Photocleavage Activity of Cationic Water-Soluble Chlorophyll Derivatives

TAIMA HIDETOSHI, OKUBO AKIHIRO, YOSHIOKA NAOKI, INOUE HIDENARI

Chemistry-A European Journal (WILEY-V C H VERLAG GMBH)  12 ( 24 ) 6331 - 6340 2006.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0947-6539

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Three cationic water-soluble chlorin e(6) derivatives, that is,6a-,gamma b-,7c-tris(2-trimethylammonioethyl)chlorin e6 (1), 6a-gamma b-,7c-tris(3-methylpyridiniummethyl)chlorin e6 (2), and 6a-,gamma b-,
7c-tris(2-trimethylammonioethyl)-2-(3-trimethylammonioprop-l-enyl)chlorin e(6) (3), have been designed and synthesized to allow the study of their DNA-binding and -photocleavage activities. The DNA-unwinding assay, measurements of melting temperatures of double-stranded DNA, and the induced CD and visible absorption spectra have revealed that 1 and 3 are intercalated into the base pairs of the double-helical DNA, while 2 is bound to outside the minor groove of the double-helical DNA. The cationic water-soluble chlorin e(6) derivatives effectively cleave the double-helical DNA under photo-irradiation and the DNA-photocleavage activity increases in the order 3 > 1 > 2. The DNA-binding and -photocleavage characteristics of the three cationic water-soluble chlorin e6 derivatives are influenced by aspects of their molecular structure, such as the kind, number, and position of the cationic substituents.

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Binding of Tetrakis(pyrazoliumyl)porphyrin and its Copper(II) and Z0inc(II) Complexes to Poly(dG-dC)(2) and Poly(dA-dT)(2)

TJAHJONO H. DARYONO, KARTASASMITA E. RAHMANA, NAWAWI AS’ARI, MIMA SHUNSUKE, AKUTSU TAKEHIRO, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Biological Inorganic Chemistry (SPRINGER)  11 ( 4 ) 527 - 538 2006.06

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0949-8257

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Interactions of cationic porphyrins bearing five-membered rings at the meso position, meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin(MPzP; M is H-2, Cu-II or Zn-II), with synthetic polynucleotides poly(dG-dC)(2) and poly(dA-dT)(2) have been characterized by viscometric, visible absorption, circular dichroisim and magnetic circular dichroism spectroscopic and melting temperature measurements. Both H(2)PzP and CuPzP are intercalated into poly(dG-dC)(2) and are outside-bound to the major groove of poly(dA-dT)(2), while ZnPzP is outside-bound to the minor groove of poly(dA-dT)(2) and surprisingly is intercalated into poly(dG-dC)(2). The binding constants of the porphyrin and poly(dG-dC)(2) and poly(dA-dT)(2) are on the order of 10(6) M-1 and are comparable to those of other cationic porphyrins so far reported. The process of the binding of the porphyrin to poly(dG-dC)(2) and poly(dA-dT)(2) is exothermic and enthalpically driven for H(2)PzP, whereas it is endothermic and entropically driven for CuPzP and ZnPzP. These results have revealed that the kind of the central metal ion of metalloporphyrins influences the characteristics of the binding of the porphyrins to DNA.

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Salt-Dependent Binding of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a : 2 ',3 '-c]phenazine to Calf Thymus DNA

Mudasir, Wijaya Kama, Wahyuni Tri Endang, Yoshioka Naoki, Inoue Hidenari

Biophysical Chemistry (ELSEVIER SCIENCE BV)  121 ( 1 ) 44 - 50 2006.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0301-4622

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The salt-dependent binding of racemic iron(II) mixed-ligand complex containing 1,10-pherianthroline (phen) and dipyrido[3,2-a:2',3'-c]phenazine (dppz), [Fe(phen)(2)(dppz)](2+) to calf thymus DNA (ct-DNA)has been characterized by UV-VIS spectrophotometric titration. The
equilibrium binding constant (K-b) of the iron(II) complex to ct-DNAdecreases with the salt concentration in the solution. The slope, SK=(delta log K-b/delta log [Na2+]) has been found to be 0.49, suggesting that, in addition to intercalation, considerable electrostatic interaction is also involved in the ct-DNA binding of [Fe(phen)(2)(dppz)](2+). The calculation of non-electrostatic binding constant (K-t degrees) based on polyelectrolyte theory has revealed that the non-electrostatic contribution to the total binding constant (K-b) increases significantly with the increase in [Na+] and reaches 36% at 0.1 M NaCl. On the other hand, the contribution of the non-electrostatic binding free energy (Delta(G) under bar (t)degrees) to the total binding free energy change (Delta G degrees) is considerably large, i.e. 87% at [Na+]=0.1 M, suggesting that the stabilization of the DNA binding is mostly due to the contribution of non-electrostatic process. Moreover, the effect of specific ligand substitutions on Delta G degrees has been rigorously evaluated using the quantity Delta Delta G(t)degrees, i.e. the difference in Delta G(t)degrees relative to that of the parent iron(II) complex,
[Fe(phen)(3)](2+), indicating that each substitution of phen by dip and dppz contributes 7.5 and 17.5 kJ mol(-1), respectively to more favorable ct-DNA binding.

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Synthesis and magnetic properties of 2,2,4-and 2,2,6-triphenyl-1,2-dihydroquinoline-N-oxyl derivatives

Yao Masaru, Shibuya Hideki, Kato Takashi, Inoue Hidenari, Yoshioka Naoki

Polyhedron (PERGAMON-ELSEVIER SCIENCE LTD)  24 ( 16-17 ) 2828 - 2834 2005.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0277-5387

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The synthesis and magnetic properties of two novel aromatic Ar-oxyl radicals based on the quinoline skeleton, 2,2,4-triphenyl-1,2-dihydroquinoline-N-oxyl (1) and 2,2,6-triphenyl-1,2-dihydroquinoline-N-oxyl (2) are described. ESR measurements and DFT calculations for 1 and 2 revealed that their spins were delocalized over the pi-systems. Based on the SQUID measurement, 1 exhibited a weak antiferromagnetic interaction in its crystal. For 2, two crystalline phases were obtained, and the alpha-phase of 2
exhibited a paramagnetic behavior; however, the beta-phase of 2 showed a weak ferromagnetic interaction. The observed ferromagnetic interaction was analyzed by a dimer model, and the singlet-triplet gap was estimated to be 2J = +2.5 cm(-1).

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Synthesis of Cationic Water-Soluble Esters of Chlorin e(6)

Taima Hidetoshi, Okubo Akihiro,Yoshioka Naoki, Inoue Hidenari

Tetrahedron Letters (PERGAMON-ELSEVIER SCIENCE LTD)  46 ( 24 ) 4161 - 4164 2005.06

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0040-4039

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Two esters of chlorin e(6) have been synthesized by esterification with aminoalcohols via the formation of acid chloride using oxalyl chloride and converted to the corresponding cationic water-soluble esters of chlorin e(6). The visible absorption and circular dichroism spectra
have revealed that these two cationic chlorin e(6) esters synthesized are readily soluble in water as a monomer.

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Formation of a One-Dimensional Stacking Structure of pi-Conjugated Nitroxyl Radical Bearing a 1,2,5-Thiadiazole Ring and its Magnetic Property

Yao Masaru, Asakura Satoshi, Abe Masahiro, Inoue Hidenari, Yoshioka Naoki

Crystal Growth & Design (AMER CHEMICAL SOC)  5 ( 2 ) 413 - 417 2005.03

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1528-7483

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A novel stable organic radical,7,7-diphenyl-6,7-dihydro[1,2,5]thiadiazolo[3,4-f]quinoline-6-oxyl (1),forms a one-dimensional columnar structure consisting of slipped,pi-stacks, which is in contrast to dimer formation of the isoelectronic benzologue,3,3-diphenyl-3,4-dihydrobenzo[f]quinoline-4-oxyl (2). Magnetic susceptibility of 1 obeyed an antiferromagnetic chain model with J =-47 cm(-1), while 2 behaved as an isolated doublet spin state even in the dimer.

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Novel Aromatic N-oxyl Radical Based on the Benzo[g]quinoline Skeleton: Synthesis and Intermolecular Ferromagnetic Interaction

Yao Masaru, Inoue Hidenari, Yoshioka Naoki

Chemical Physics Letters (ELSEVIER SCIENCE BV)  402 ( 1-3 ) 11 - 16 2005.01

Research paper (scientific journal), Single Work, Accepted,  ISSN  0009-2614

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A novel stable organic radical,2,2-diphenyl-1,2-dihydrobenzo[g]quinoline-N-oxyl (2), has been synthesized and structurally characterized in order to examine the ring
extension effect on the known derivative, 2,2-diphenyl-1,2-dihydroquinoline-N-oxyl (1). Based on SQUID measurement, 2 exhibited a ferromagnetic interaction obeying the Bleaney-Bowers equation with 2J = +4.6 cm(-1). The X-ray analysis revealed an intermolecular edge-edge association of the aryl ring and N-oxyl moiety in the crystal of 2. The bifurcated edge-edge contacts between the alpha-spin site (nitroxyl O atom) and the beta-spin site (aryl-H atoms) are responsible for the ferromagnetic interaction of 2.

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Amphiphilic meso-Disubstituted Porphyrins: Synthesis and the Effect of the Hydrophilic Group on Absorption Spectra at the Air-Water Interface

Yao Masaru, Iwamura Yuko,Inoue Hidenari, Yoshioka Naoki

Langmuir (AMER CHEMICAL SOC)  21 ( 2 ) 595 - 601 2005.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0743-7463

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Five amphiphilic meso-disubstituted porphyrins bearing one polar group were synthesized. and their monolayer films were prepared. Their limiting molecular areas obtained from pi-A isotherms were 0.5-0.6nm(2), which were smaller than those of the corresponding meso-tetrasubstituted porphyrins. At the air-water interface, the disubstituted porphyrins showed a broad band in visible absorption spectra compared with the solution state, and the red shift of the Soret band exhibited a significant dependence on the kind of hydrophilic groups at the meso positions. Interestingly, the monolayer of the disubstituted porphyrin bearing a carboxyphenyl group (1-CO2H) showed a blue shift of the Soret band by adding cadmium chloride to the subphase, and the spectra varied upon multilayer deposition. The observed phenomena were interpreted by using the exciton theory. The effect of hydrophilic substituents on the absorption Spectra of disubstituted porphyrin monolayers is discussed.

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An Ideal One-Dimensional Antiferromagnetic Spin System Observed in Hydrogen-Bonded Naphth[2,3-d]imidazol-2-yl Nitronyl Nitroxide Crystal:The Role of the Hydrogen Bond

NAGASHIMA HIDEAKI, INOUE HIDENARI, YOSHIOKA NAOKI

Journal of Physical Chemistry B 108 ( 20 ) 6144 - 6151 2004.05

Research paper (scientific journal), Joint Work, Accepted

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A novel stable organic radical, 2-(naphth[2,3-d]imidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide (4), has been designed, synthesized, and structurally characterized to examine the effects of ring extension on 2-(benzimidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide (2). 4 forms four-centered intramolecular and intermolecular hydrogen bonds, and the hydrogen bonds are repeated along the c-axis to form a one-dimensional chain structure. This hydrogen-bonding motif contrasts that of 2, which forms three-centered intramolecular and intermolecular hydrogen bonds. The magnetic susceptibility measurement of 4 reveals that an antiferromagnetic interaction is dominant between spins, and the magnetic behavior is reproduced by the Bonner-Fisher model with J = −14 cm-1. Because each hydrogen-bonded chain is well isolated, a magnetic interaction pathway was thought to exist along the chain direction. Two interaction pathways have been assumed:  (i) through-space interaction between the O atoms of the nitroxide and (ii) through the NH···ON intermolecular hydrogen bond. We have concluded that pathway (i) is predominant, by considering the identical magnetic data between the NH nondeuterated and deuterated samples. The hydrogen bond mainly has a role in crystal scaffolding.

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DNA-Binding Properties of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a : 2 ',3 '-c]phenazine

MUDASIR, WIJAYA, Karna, YOSHIOKA NAOKI, INOUE HIDENARI

Zeitschrift für Naturforschung B (VERLAG Z NATURFORSCH)  59 ( 3 ) 310 - 318 2004.03

Research paper (scientific journal), Joint Work, Accepted

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An iron(II) mixed-ligand complex with 1,10-phenanthroline (phen) and dipyrido[3,2-a:2’,3’- c]phenazine (dppz), [Fe(phen)2(dppz)]2+, has been synthesized. The DNA-binding properties of the mixed-ligand complex have been studied in terms of equilibrium binding constant, thermodynamic parameter, thermal denaturation as well as Pfeiffer effect upon binding to DNA. The spectrophotometric titration of [Fe(phen)2(dppz)]2+ with calf thymus DNA (ct-DNA) has shown that the iron(II) mixed-ligand complex binds effectively to ct-DNA in an intercalation mode as indicated by remarkable hypochromicity (ca. 36%) and moderate bathochromic shift (8 nm) of the absorption spectra. This intercalative mode is supported by a significant increase (Δ Tm = 21 °C) in the melting temperature (Tm) of ct-DNA at R([complex]/[ct-DNA]) = 1.5. The binding of [Fe(phen)2(dppz)]2+ to ct-DNA is entropically driven as characterized by a positive enthalpy change and a large negative TΔ S term. An intense CD signal in the UV and visible region develops upon addition of ct-DNA to the racemate solution of [Fe(phen)2(dppz)]2+. This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one enantiomer of the DNA-iron(II) complex (Pfeiffer effect). The striking resemblance of the CD spectral profiles to those of the corresponding Δ -enantiomer indicates that Δ -[Fe(phen)2(dppz)]2+ is preferentially bound to ct-DNA

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Metamagnetic Behavior Observed in Purely Organic 5-Azaindol-2-yl Nitronyl Nitroxide Brick-Wall Architecture

NAGASHIMA HIDEAKI, FUJITA SHIN'YA, INOUE HIDENARI, YOSHIOKA NAOKI

Crystal Growth & Design 4 ( 1 ) 19 - 21 2004.01

Research paper (scientific journal), Joint Work, Accepted

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A novel stable organic radical, 2-(5-azaindol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazoline-1-oxyl-3-oxide (3), forms a two-dimensional brick-wall architecture based on hydrogen bonding and π-stacking. Low-temperature magnetization curves reveal an S-shape dependence on the applied field below ca. 3.0 K, which could be interpreted as metamagnetic behavior.

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Interaction of Dicationic Bis(imidazoliumyl)porphyrinatometals with DNA

Yamamoto Tomoko, Tjahjono Hadi Daryono, Yoshioka Naoki, Inoue Hidenari

Bulletin of the Chemical Society of Japan 76 ( 10 ) 1947-1955 - 1955 2003.10

Research paper (scientific journal), Joint Work, Accepted

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A pair of dicationic metalloporphyrins with only two meso-substituents, i.e. copper(II) and zinc(II) complexes of 5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrin (H2-1), have been synthesized by insertion reaction of the metal ions. Interactions of [5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrinato]copper(II) (Cu-I) and [5,15-bis(1,3-dimethylimidazolium-2-yl)porphyrinato]zinc(II) (Zn-1) with calf thymus DNA (CT-DNA) and double-helical synthetic polynucleotides ([poly(dA-dT)]2 and [poly(dG-dC)]2) have been studied by melting temperature, viscometric, visible absorption, CD and MCD spectroscopic measurements. The copper(II) complex, Cu-1, intercalates into the base pairs of DNA such as CT-DNA, [poly(dA-dT)]2 and [poly(dG-dC)]2 to stabilize the DNA duplex due to its high affinity for them. In contrast, the zinc(II) complex, Zn-1, binds edge-on to CT-DNA, [poly(dA-dT)]2 and [poly(dG-dC)]2 as an outside binder. The binding constant of Cu-1 to DNA is in the order of 106 M-1 in a phosphate buffer (pH 6.8) at 25 °C, while that of Zn-1 ranges from 104 to 10 5 M-1 under the same experimental conditions. The binding of Cu-1 and Zn-1 to DNA is entropically driven, although that of H 2-1 is enthalpically driven. As a result, it has been revealed that the kind of central metal ions in dicationic metalloporphyrins influences the binding properties of the dicationic porphyrin to DNA.

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Synthesis, Solution ESR Spectra, and Solid-State Magnetic Property of Thieno[3,4-d]imidazol-2-yl Nitronyl Nitroxide

NAGASHIMA HIDEAKI, INOUE HIDENARI, YOSHIOKA NAOKI

Polyhedron 22 ( 14-17 ) 1823 - 1827 2003.07

Research paper (scientific journal), Joint Work, Accepted

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2-(Thieno[3,4-d]imidazol-2-yl)-1,3-dihydro-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (2) was designed and synthesized. Compound 2 was stable in a solid state but unstable in organic solvents. Solution ESR spectra showed that small spin densities locate on the four methyl groups and the thieno[3,4-d]imidazole ring, though most of spin densities localized on the ONCNO moiety. Magnetic susceptibility measurement showed that antiferromagnetic interaction is dominant which could be fitted to the Bonner–Fisher model with J=−8.8 cm−1.

A new nitronyl nitroxide derivative carrying thieno[3,4-d]imidazole ring was designed and synthesized. It was stable in a solid state but unstable in organic solvents. Solution ESR spectra showed that small spin densities locate on the four methyl groups and the thieno[3,4-d]imidazole ring. Magnetic susceptibility measurement showed that antiferromagnetic interaction is dominant which could be fitted to the Bonner–Fisher model with J=−8.8 cm−1.

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Synthesis and Physicochemical Properties of Some 5,15-Diarylporphyrin Derivatives

YAO MASARU, KAMISHIRO MASAFUMI, INOUE HIDENARI, YOSHIOKA NAOKI

Polyhedron 22 ( 14-17 ) 2281 - 2285 2003.07

Research paper (scientific journal), Joint Work, Accepted

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Several derivatives of meso-5,15-diarylporpyrins (1–4) and their metal complexes were prepared and their physicochemical properties were studied. Their magnetic properties were characterized by SQUID magnetometer. The temperature dependence of the molar magnetic susceptibility of the copper and vanadyl complex of 5,15-diphenylporphyrin (1-Cu, 1-VO) obeyed the Curie law and were almost identical with those of corresponding meso-tetraphenyl derivatives. In addition to the magnetic properties of disubstituted porphyrins, the properties of Langmuir film of meso-disubstituted porphyrins 2-H2 were investigated by π–A isotherms and visible absorption spectra.

meso-Diphenylmetalloporpyrins (M=Cu, VO) were prepared and their magnetic properties were characterized. These derivatives obeyed the Curie law and were almost identical with those of corresponding meso-tetraphenyl derivatives. Prepared amphiphilic diarylporphyrin showed a large red shift pattern in the visible absorption spectrum at air–water interface, compared with in the solution.

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Theoretical study on magnetic properties of imidazolyl nitronyl nitroxide derivatives

NAGASHIMA HIDEAKI, INOUE HIDENARI, YOSHIOKA NAOKI

Synthetic Metals 137 ( 1-3 ) 1257 - 1258 2003.04

Research paper (scientific journal), Joint Work, Accepted

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imidazol-2-yl nitronyl nitroxideとbenzimidazol-2-yl nitronyl nitroxideは、水素結合により連鎖構造を形成し、前者は強い反強磁性、後者は強磁性相互作用が存在する。構造－磁性相関より、磁気的相互作用として水素結合を介する経路と、空間を介した磁気軌道の接近による経路が考えられる。DFT計算を活用してこれら２つのラジカル分子では、磁気軌道の直積的な接近が主要な経路であることを明らかにした。

Coexistence of an Antiferromagnetically Coupled Dimer and Isolated Paramagnetic Spin in 4-Azaindol-2-yl Nitronyl Nitroxide Crystal

NAGASHIMA HIDEAKI, HASHIMOTO NORIKO, INOUE HIDENARI, YOSHIOKA NAOKI

New Journal of Chemistry (Royal Society of Chemistry)  27 ( 5 ) 805 - 810 2003.04

Research paper (scientific journal), Joint Work, Accepted

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A novel stable organic radical, 2-(4-azaindol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazoline-1-oxyl-3-oxide was synthesized and its magneto-structual correlation is discussed.

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Effect of Hydrophilic Group on Absorption Spectra of meso-Disubstituted Porphyrin LB Films

YAO MASARU, ISHIDA NAOMI, INOUE HIDENARI, YOSHIOKA NAOKI

Synthetic Metals 137 ( 1-3 ) 917 - 918 2003.04

Research paper (scientific journal), Joint Work, Accepted

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両親媒性基を導入したmeso-２置換ポルフィリン誘導体を合成し、これを膜物質とするLB膜を作製した。膜の光吸収特性に及ぼす、導入置換基の効果を各種分光法を用いて明らかにした。

ESR Study and Deuteration Effect on the Magnetic Property of Hydrogen-Bonded Benzimidazole Nitronyl Nitroxide

NAGASHIMA HIDEAKI, IRISAWA MUNETOSHI, YOSHIOKA NAOKI, INOUE HIDENARI

Molecular Crystals and Liquid Crystals 376 ( 1 ) 371 - 376 2002.03

Research paper (scientific journal), Joint Work, Accepted

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A solution ESR spectral investigation on 2-(benzimidazol-2-yl)-4,4,5,5-tetramethyl-1 H -imidazoline-1-oxyl-3-oxide (=BIm-NN) and a magnetic susceptibility measurement of its −(N)H deuterated sample (BIm-NN-d 1 ) were carried out. A moderate amount of spin density was observed in benzimidazole ring bearing a hydrogen-bonding site. There was no appreciable difference in the temperature dependence of magnetic susceptibility between BIm-NN and BIm-NN-d 1 .

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Self-Assembly of a Porphyrin Array via the Molecular Recognition Approach: Synthesis and Properties of a Cyclic Zinc(II) Porphyrin Trimer Based on Coordination and Hydrogen Bonding

IKEDA CHUSAKU, TANAKA YUICHI, FUJIHARA TAKESHI, ISHII YOKO, USHIYAMA TAKESHI, YAMAMOTO KIMIHISA, YOSHIOKA NAOKI, INOUE HIDENARI

Inorganic Chemistry 40 ( 14 ) 3395 - 3405 2001.08

Research paper (scientific journal), Joint Work, Accepted

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Self-assembly of [5-(pyrazol-4-yl)-10,20-bis(p-tolyl)-15- (2-ethoxycarbonylphenyl)porphyrinato]-zinc(II) (1), designed to have both a coordination site and a hydrogen bonding site, leads to a stable cyclic trimer array where coordination of the pyrazole nitrogen to the zinc(II) ion as well as hydrogen bonding between carbonyl oxygen and pyrazole NH holds each zinc(II) porphyrin. The recognition event for pyrazole has been confirmed preliminarily in the model studies using [5-(2-ethoxycarbonylphenyl)tris(p-tolyl)porphyrinato]-zinc(II) (3). The zinc(II) porphyrin 3 has large affinity for pyrazole due to the hydrogen bond between pyrazole and the 2-ethoxycarbonyl group in addition to the coordination bonding accompanied by the conformational change of the ethoxycarbonyl group in the coordination process. The 1H NMR, IR, and UV−vis spectra of 1 and its ESI-MS and VPO measurements have revealed the cyclic trimer structure with an overall association constant of 6.0 × 1013 M-2 at 22 °C. The contribution of the hydrogen bond to the total free energy change in trimer formation is estimated to be 7.5 kcal/mol based on a reference trimer system without a hydrogen bonding site. The trimer geometry causes characteristic exitonic interaction between porphyrin units to yield a broad Soret band which is deconvoluted into four components by UV−vis and MCD spectral analyses. Electrochemical measurements have shown that only the first ring-oxidation process proceeds stepwise in the trimer.

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