Details of a Researcher - Yoshioka, Naoki

Papers - Yoshioka, Naoki

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Synthesis of Carbazole-Based Selenaporphyrin via Annulation

MASUDA MOTOKI, MAEDA CHIHIRO, YOSHIOKA NAOKI

Organic Letters (American Chemical Society) 15 ( 3 ) 578 - 581 2013.01

Research paper (scientific journal), Single Work, Accepted

Cu(I)-mediated alkoxylation of doubly 1,3-butadiyne-bridged carbazole dimer 1, followed by acid-catalyzed cyclization, provided furan-bridged carbazole dimer 3, while annulation reaction of 1 with selenium in the presence of hydrazine monohydrate provided selenophene-bridged carbazole dimer 5a. Oxidation of isophlorin 5a afforded carbazole-based selenaporphyrin 5b, which possessed distinct aromaticity and produced intensified and red-shifted absorption bands in the near-IR region.

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Peripherally Ethynylated Carbazole-Based Core-Modified Porphyrins

MAEDA CHIHIRO, YOSHIOKA NAOKI

Organic & Biomolecular Chemistry 10 5182-5185 2012.05

Research paper (scientific journal), Single Work, Accepted

Magnetic Tuning of All-Organic Binary Alloys between Two Stable Radicals

SEBER GONCA , FREITAS S. RAFAEL, MAGUE T. JOEL, PADUAN-FILHO ARMANDO, GRATENS XAVIER, BINDILATTI VALDIR, OLIVEIRA NEI FERNANDES JR., YOSHIOKA NAOKI, LAHTI M. PAUL

Journal of the American Chemical Society 134 ( 8 ) 3825-3833 2012.04

Research paper (scientific journal), Joint Work, Accepted

Synthesis and Characterization of Novel Fused Porphyrinoids Based on Cyclic Carbazole[2]indolones

MAEDA CHIHIRO, YOSHIOKA NAOKI

Organic Letters (American Chemical Society) 14 ( 8 ) 2212 - 2125 2012.04

Research paper (scientific journal), Single Work, Accepted

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Theoretical Study of Intermolecular Magnetic Interaction of Chromium(V)-Nitrido Complex Self-Assembly with Tetradentate Schiff Base Ligand

MATSUOKA NAOKI, YOSHIOKA NAOKI

Chemical Physics Letters 523 65-68 2012.01

Research paper (scientific journal), Joint Work, Accepted

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Theoretical Study of Magnetic Properties of Oxovanadium(IV) Complex Self-Assemblies with Tetradentate Schiff Base Ligands

MATSUOKA NAOKI, TSUCHIMOTO MASANOBU, YOSHIOKA NAOKI

The Journal of Physical Chemistry B 115 ( 26 ) 8465 - 8473 2011.07

Research paper (scientific journal), Joint Work, Accepted

he theoretical study of the magnetic properties of oxovanadium(IV) complex self-assemblies with tetradentate Schiff base ligands is discussed on the basis of DFT calculations. Large negative spin densities are found on the axial oxygens of the various oxovanadium(IV) complexes. The relationship between the effective exchange parameters Jab and the geometrical parameters for these complexes was studied by changing the position of the neighboring molecules for the purpose of clarifying the mechanism of the ferromagnetic coupling. The intermolecular ferromagnetic interaction of the oxovanadium(IV) complexes with tetradentate Schiff base ligands is significantly affected by the formation of polymeric octahedral structures in the solid state. The overlap between the 2p orbitals of the axial oxygen and the 3d orbitals of the adjacent vanadium is effective for the ferromagnetic coupling. On the other hand, the effect of overlap between the vanadium 3dxy orbitals is too small to lead to magnetic coupling. It was revealed that the intermolecular ferromagnetic interaction of the polynuclear oxovanadium(IV) complexes is significantly affected by the spin polarization on the axial oxygen.

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Synthesis of Carbazole-Containing Porphyrirnoids by a Multiple Annulation Strategy: A Core-Modified and pi-Expanded Porphyrin

MAEDA CHIHIRO, YONEDA TOMOKI, ARATANI NAOKI, YOON MIN-CHUL, LIM JONGMIN, KIM DONGO, YOSHIOKA NAOKI, OSUKA ATSUHIRO

Angewande Chemie-International Edition 50 ( 25 ) 5691 - 5694 2011.06

Research paper (scientific journal), Joint Work, Accepted

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Spectroscopic Studies on the Thermodynamic and Thermal Denaturation of the CT-DNA Binding of Methylene Blue

Mudasir, Wahyuni Tri Endang, Tjahjono H. Daryono, YOSHIOKA NAOKI, INOUE HIDENARI

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy 77 ( 2 ) 528 - 534 2010.10

Research paper (scientific journal), Single Work, Accepted, ISSN 1386-1425

The ct-DNA binding properties of methylene blue (MB) including binding constant, thermodynamic parameter and thermal denaturation (T(m)) have been systematically studied by spectrophotometric method. The binding of MB to ct-DNA is quite strong as indicated by remarkable hypochromicity, red shift and equilibrium binding constant (K(b)). Van't Hoff plot of 1/T versus lnK(b) suggests that the MB dye binds exothermically to ct-DNA which is characterized by large negative enthalpy and entropy changes. According to polyelectrolyte theory, the charge release (Z) when ct-DNA interacts with MB is +1.09 which corresponds very well to the one positive charge carried by the MB dye. The K(b) at a low concentration of salt is dominated by electrostatic interaction (90%) while that at a high concentration of salt is mostly controlled by non-electrostatic process (85%). However, the stabilization of the DNA binding event in both cases is governed by non-electrostatic process. A moderate stabilization of double helix ct-DNA occurs when the MB dye binds to ct-DNA as indicated by the increase in T(m) of ct-DNA of about 5.5 degrees C in the presence of MB. This suggests that MB dye possibly binds to ct-DNA via electrostatic and intercalation modes.

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Binding of Nickel(II) Tetrakis(dimethylpyrazolium-4-yl)porphyrin to Poly(dG-dC)(2) and Poly(dA-dT)(2)

Tjahjono Daryono HADI, SUHENDAR, PERMANA BENNY, YOSHIOKA NAOKI, INOUE HIDENARI

Journalof Porphyrins and Phthalocyanines 14 ( 4 ) 305 - 313 2010.04

Research paper (scientific journal), Joint Work, Accepted, ISSN 1088-4246

The interaction of nickel(II) complex of cationic porphyrins bearing five-membered rings, meso-tetrakis(1,2-dimethylpyrazolium-4-yl) porphyrinatonickel(II) (NiPzP), with synthetic polynucleotides poly(dG-dC) 2 and poly(dA-dT) 2 has been characterized by viscometric, visible absorption, CD and MCD spectroscopic, and melting temperature measurements. The nickel(II) complex NiPzP is intercalated into poly(dG-dC) 2 but outside bound to the major groove of poly(dA-dT) 2. The binding constants of NiPzP to poly(dG-dC) 2 and poly(dA-dT) 2 are in the order of 10 6 M -1 and comparable to those of other reported cationic metalloporphyrins. The binding process of NiPzP to poly(dG-dC) 2 and poly(dA-dT) 2 is endothermic and entropically driven.

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Magnetic Property and Crystal Structure of Bis[N-(4-chlorophenyl)salicylideneaminato]oxovanadium (IV)

MATSUOKA NAOKI, KAWAMURA HIROSHI, YOSHIOKA NAOKI

Chemical Physics Letters (ELSEVIER SCIENCE INC) 488 ( 1-3 ) 32 - 37 2010.03

Research paper (scientific journal), Joint Work, Accepted

Synthesis and DNA-Binding Properties of Water-Soluble Cationic Pyropheophorbides Derived from Chlorophyll a/b

TAIMA HIDETOSHI, YOSHIOKA NAOKI, INOUE HIDENARI

Organic & Biomolecular Chemistry (Royal Society of Chemistry) 7 ( 6 ) 1176 - 1183 2009.06

Research paper (scientific journal), Joint Work, Accepted

A series of mono-, di-, tetra-and hexacationic esters of pyropheophorbide a/b have been designed and synthesized to explore the intercalation of their phorbine ring between the base pairs of double-helical DNA and the influence of their peripheral substituents on the DNA interactions. Mono-(1), di-(2, 3) and tetra-(4, 5) cationic pyropheophorbides are soluble as an oligomeric aggregate in HEPES buffer, but hexa-(6) cationic pyropheophorbide is soluble as a monomer at lower concentrations. The interaction of these cationic pyropheophorbide derivatives with DNA has been investigated by DNA unwinding assay,fluorescence energy transfer, and measurements of the melting temperature of the double-helical DNA and visible absorption spectra. Dicationic 2 and 3 bind outside the double-helical DNA without and/or with self-aggregation and with self-aggregation, respectively, because they cannot intercalate between the base-pairs due to their aggregation. On the other hand, tetracationic 4 and 5 and hexacationic 6 intercalate between the base pairs of the double-helical DNA. The binding mode of the cationic pyropheophorbides a/b is strongly dependent on the number and position of the cationic peripheral substituents of the pyropheophorbides.

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Electronic Structures and Magnetic Properties of Copper(II) Complexes with Axially Coordinated Nitronyl Nitroxide Radicals

MATSUOKA NAOKI, YOSHIOKA NAOKI

Polyhedron (PERGAMON-ELSEVIER SCIENCE LTD) 28 ( 9-10 ) 1875 - 1879 2009.06

Research paper (scientific journal), Joint Work, Accepted

Electronic structures and magnetic properties of Cu(II) complexes with axially coordinated nitronyl nitroxide radicals are discussed on the basis of computational study using density functional theory (DFT) calculation. The tendency of the effective exchange integrals J is examined by changing the position of the nitronyl nitroxide moiety. The spin density distributions for these complexes are also estimated in order to understand the mechanism of the ferromagnetic interaction. The relationship between the geometrical parameters and the magnetic interaction indicates the delocalization of the unpaired electron from the π* orbital of the nitronyl nitroxide group to the 3dz2 atomic orbital of the Cu(II) ion. On the other hand, there is practically no dependence of the overlap between the 3dx2-y2 atomic orbital of the Cu(II) ion and the π* orbital of the nitronyl nitroxide group on the magnitude of the ferromagnetic coupling. It is revealed that the delocalization mechanism is important for the ferromagnetic properties in Cu(II) complexes with axially coordinated nitronyl nitroxide radicals.

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Enantioselective DNA Binding of Iron(II) Complexes of Methyl-Substituted Phenanthroline

MUDASIR, YOSHIOKA NAOKI, INOUE HIDENARI

Journal of Inorganic Biochemistry (ELSEVIER SCIENCE INC) 102 ( 8 ) 1638 - 1643 2008.08

Research paper (scientific journal), Single Work, Accepted

The enantioselective binding of [Fe(4,7-dmp)(3)](2+) (dmp: 4,7-dimethyl-1,10-phenantroline) and [Fe(3,4,7,8-tmp)(3)](2+) (tmp: 3,4,7,8-tetramethyl-1,10-phenanthroline) to calf-thymus DNA (ct-DNA) has been systematically studied by monitoring the circular dichroism (CD) spectral profile of the iron(II) complexes in the absence and presence of ct-DNA. The effect of salt concentration and temperature on the degree of enantioselectivity of the ct-DNA binding of the iron(II) complexes, i.e. the molar ratio of Delta- to Lambda-enantiomer in the solution or vice versa has been rigorously evaluated. It is noticeable that Delta-[Fe(4,7-dmp)(3)](2+) and Lambda-[Fe(3,4,7,8-tmp)(3)](2+) are preferentially bound to ct-DNA as reflected in their opposite CD spectral profiles. The preferential binding of the A-enantiomer of [Fe(3,4,7,8-tmp)(3)](2+) to ct-DNA compared to that of the A-enantiomer is associated with the bulkiness of the ancillary ligands due to substitution of four hydrogen atoms in 1,10-phenanthroline for four methyl groups. The determination of enantiomeric inversion constant (K-inv) at various salt concentrations has revealed that the degree of enantioselectivity is salt concentration dependent, indicating that electrostatic interaction is involved in the enantioselective binding of the iron(II) complexes to ct-DNA. Although [Fe(4,7-dmp)(3)](2+) and [Fe(3,4,7,8-tmp)(3)](2+) exhibit an opposite pattern in the CD spectra, the degree of their enantioselectivity (K-inv) is not different from each other significantly. A thermodynamic study on the enantioselective binding of [Fe(4,7-dmp)(3)](2+) to ct-DNA using the van't Hoff plot of lnK(inv) versus 1/T has demonstrated that the enthalpy change (Delta H-o) in the inversion process from the Lambda- to Delta-enantiomer of [Fe(4,7-dmp)(3)](2+) ct-DNA is positive, indicating that the process is endothermic and thus entropically driven. @ 2008 Elsevier Inc. All rights reserved.

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DNA Binding of Iron(II)-Phenanthroline Complexes: Effect of Methyl Substitution on Thermodynamic Parameters

MUDASIR，YOSHIOKA NAOKI,INOUE HIDENARI

Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences (VERLAG Z NATURFORSCH) 63 ( 1 ) 37 - 46 2008.01

Research paper (scientific journal), Joint Work, Accepted

The influence of methyl substitution on the thermodynamic parameters for the binding of [Fe(DMP)(3)](2+) and [Fe(TMP)(3)](2+) (DMP = 4,7-dimethyl-1,10-phenanthroline, TMP = 3,4,7,8-tetramethyl-1,10-phenanthroline) to calf thymus DNA (ct-DNA) has been studied by determining their equilibrium binding constants (K-b) at various salt concentrations and temperatures. Kb of the iron(II) complexes to ct-DNA decreases with the salt concentration in the solution, suggesting considerable electrostatic interaction in the ct-DNA binding of the iron(II) complexes. In contrast, Kb of the DNA binding increases with temperature, indicating that the DNA binding reaction of the complex is endothermic and entropically driven. The evaluation of the non-electrostatic binding constant (K-t(0)) based on polyelectrolyte theory has revealed that the K-t(0) portions of the total binding constant (Kb) are relatively large and reach 46.4% for [Fe(DMP)3]2+ at [Na+] = 0.075 m and 43.9% for [Fe(TMP)(3)](2+) at [Na+] = 0.100 M. The contribution of non-electrostatic binding free energy (Delta G(t)(0)) to total binding free energy change (AGO) is extremely large, L e. > 90 % for both iron(II) complexes at [Na+] = 0.05 M, suggesting that the stabilization of the DNA binding is mainly contributed from the non-electrostatic process. The effect of methyl substitution on electrostatic (AGO and non-electrostatic (Delta G(t)(0)) binding free energy changes has been systematically evaluated using the quantity of Delta Delta G(pe)(0) and Delta Delta G(t)(0) relative to that of the parent iron(II) complex, [Fe(phen)(3)](2+). The results indicate that the substitution of hydrogen atoms in the phen ligand by methyl groups decreases slightly the electrostatic binding free energy changes, but tremendously increases the non-electrostatic ones to yield net binding free energy changes which are more favorable for the ct-DNA binding.

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An Organic Radical Solid Solution with Strong Ferromagnetic Exchange

MURATA HIDENORI, MAGUE T. JOEL,ABOAKU SAFO, YOSHIOKA NAOKI, LAHTI M. PAUL

Chemistry of Materials (AMER CHEMICAL SOC) 19 ( 17 ) 4111 - 4113 2007.08

Research paper (scientific journal), Joint Work, Accepted

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Base-Specific and Enantioselective Studies for the DNA Binding of Iron(II) Mixed-Ligand Complexes Containing 1,10-Phenanthroline and Dipyrido[3,2-a : 2 ',3 '-c]phenazine

MUDASIR, WIJAYA KARNA,WAHYUNI TRI ENDANG, INOUE HIDENARI, YOSHIOKA NAOKI

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy (PERGAMON-ELSEVIER SCIENCE LTD) 66 ( 1 ) 163 - 170 2007.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 1386-1425

Base specificity and enantioselectivity for the DNA binding of [Fe(phen)(2)(dppz)](2+) (phen = 1, 10-phenanthroline and dppz =dipyrido[3,2-a:2,3'c]phenazine) have been studied by determining the equilibrium binding constant (K-b) of the iron(II) complex to calf thymus DNA (ct-DNA), poly[(dA-dT)(2)], poly[(dG-dC)(2)] and poly[(dI-dC)(2)] using spectrophotometric titration and by monitoring the CD spectral profile of the iron(II) complex in the presence and absence of different types of DNA using circular dichroism (CD) spectroscopy, respectively. It has been shown that [Fe(phen)(2)(dppz)](2+) prefers to intercalate into the A-T and I-C sequences of poly[(dA-dT)(2)] and poly[(dI-dC)(2)] rather than into the G-C sequences of poly[(dG-dC)21 or into the base pairs of ct-DNA. In contrast to previous reports, it is a surprising observation that the enantioselectivity of the DNA binding for [Fe(phen)2(dppZ)]21 is base-dependent in nature. The A-enantiomer of [Fe(phen)2(dppz)]2, is preferentially intercalated into the base pairs of poly[(dG-dC)21 or ct-DNA as indicated by its CD spectral profiles. On the other hand, the A-enantiomer of [Fe(phen)2(dppZ)]2, is favorably intercalated into poly[(dA-dT)(2)] or poly[(dI-dC)(2)] as suggested by the opposite CD spectral profile. This preferential binding of A-[Fe(phen)(2)(dppz)](2+) for the A-T sequence may be attributed to the fact that the binding site for the A-T sequence is relatively facile and thus the steric effect caused by the ancillary (non intercalated)phen ligands is alleviated. The degree of enantioselectivity represented by inversion constants (K-inv) decreases as the salt concentration in the solution increases, indicating that electrostatic interaction is also operating in the ct-DNA-binding events of the iron
(II) complex.

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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

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

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

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

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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