bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunosuppressive components of Ascaris suum down‐regulate expression of costimulatory molecules and function of antigen‐presenting cells via an IL‐10‐mediated mechanism
Authors: Silva Sandriana R. , Jacysyn Jacqueline F. , Macedo Mahasti S. , Faquim‐Mauro Eliana L. 
Published: November 2006

AbstractHigh‐molecular‐weight components (PI) of Ascaris suum suppress both cell‐mediated and humoral responses against ovalbumin (OVA) via an IL‐4/IL‐10‐dependent mechanism. The aim of this work was to investigate the effect of PI on the ability of APC to activate T cells and the role of IL‐10 in this process. Flow cytometry analyses of MHC class II, CD80, CD86 and CD40 molecules on LN cells from mice immunized with OVA or OVA+PI showed that PI inhibits expression of these molecules on unfractionated cells and on purified CD11c+ cells. A low proliferative response was obtained when OVA‐specific TCR‐Tg T cells were incubated with CD11c+ cells from OVA+PI‐immunized mice pulsed with OVA, when compared to those incubated with cells from OVA‐immunized mice. Similar results were obtained using as APC CD11c+ cells from OVA‐immunized mice pulsed with OVA+PI, which also expressed less of the four markers. The inhibitory effect of PI on both the expression of costimulatory molecules and the induction of T cell proliferation was abolished in IL‐10‐deficient mice. Our data indicate that the potent immunosuppressive effect of A. suum extract components on the host immune system is primarily related to their property of down‐regulating the Ag‐presenting ability of DC via an IL‐10‐mediated mechanism.
α2,3‐Sialyltransferase‐IV is essential for L‐selectin ligand function in inflammation
Authors: Sperandio Markus , Frommhold David , Babushkina Inna , Ellies Lesley G. , Olson Timothy S. , Smith Michael L. , Fritzsching Benedikt , Pauly Eva , Smith David F. , Nobiling Rainer , Linderkamp Otwin , Marth Jamey D. , Ley Klaus 
Published: November 2006

AbstractL‐selectin belongs to the C‐type lectin family of glycoproteins and is constitutively expressed on most leukocytes. L‐selectin mediates leukocyte rolling in inflamed microvessels and high endothelial venules (HEV) via binding to specific carbohydrate structures on selectin ligands. Previous studies using sialidase treatment suggested a role of sialic acid residues in L‐selectin‐dependent rolling. To investigate the role of the α2,3‐sialyltransferase (ST3Gal)‐IV on L‐selectin ligand activity in vivo, we studied leukocyte rolling in inflamed venules of the cremaster muscle and in Peyer's patch HEV of ST3Gal‐IV‐deficient mice and littermate control mice. In cremaster muscle venules with or without TNF‐α treatment, L‐selectin‐dependent rolling was almost completely abolished in ST3Gal‐IV–/– mice. In both models, L‐selectin interacts with P‐selectin glycoprotein ligand‐1 (PSGL‐1) presented by adherent leukocytes and leukocyte fragments, but not with endothelial L‐selectin ligands. In contrast, L‐selectin‐dependent rolling in Peyer's patch HEV, which is mediated by unknown endothelial L‐selectin ligands, was not impaired in the absence of ST3Gal‐IV. Our in vivo data show that PSGL‐1, the molecule responsible for L‐selectin‐mediated leukocyte interactions in inflammation, is dependent on ST3Gal‐IV, while α2,3‐sialylation by ST3Gal‐IV is not necessary for L‐selectin ligand activity on high endothelial cells of Peyer's patch HEV.
CD4+ T cells specific for a model latency‐associated antigen fail to control a gammaherpesvirus in vivo
Authors: Smith Christopher M. , Rosa Gustavo T. L. , May Janet S. , Bennett Neil J. , Mount Adele M. , Belz Gabrielle T. , Stevenson Philip G. 
Published: November 2006

AbstractCD4+ T cells play a major role in containing herpesvirus infections. However, their cellular targets remain poorly defined. In vitro CD4+ T cells have been reported to kill B cells that harbor a latent gammaherpesvirus. We used the B cell‐tropic murine gammaherpesvirus‐68 (MHV‐68) to test whether this also occurred in vivo. MHV‐68 that expressed cytoplasmic ovalbumin (OVA) in tandem with its episome maintenance protein, ORF73, stimulated CD8+ T cells specific for the H2‐Kb‐restricted OVA epitope SIINFEKL and was rapidly eliminated from C57BL/6 (H2b) mice. However, the same virus failed to stimulate CD4+ T cells specific for the I‐Ad/I‐Ab‐restricted OVA323–339 epitope. We overcame any barrier to the MHC class II‐restricted presentation of an endogenous epitope by substituting OVA323–339 for the CLIP peptide of the invariant chain (ORF73‐IRES‐Ii‐OVA), again expressed in tandem with ORF73. This virus presented OVA323–339 but showed little or no latency deficit in either BALB/c (H2d) or C57BL/6 mice. Latent antigen‐specific CD4+ T cells therefore either failed to recognize key virus‐infected cell populations in vivo or lacked the effector functions required to control them.
The structure of the human allo‐ligand HLA‐B*3501 in complex with a cytochrome p450 peptide: Steric hindrance influences TCR allo‐recognition
Authors: Hourigan Christopher S. , Harkiolaki Maria , Peterson Neil A. , Bell John I. , Jones E. Yvonne , O'Callaghan Chris A. 
Published: November 2006

AbstractVirus‐specific T cell populations have been implicated in allo‐recognition. The subdominant T cell receptor JL12 recognizes both HLA‐B*0801 presenting the Epstein–Barr virus‐derived peptide FLRGRAYGL and also HLA‐B*3501 presenting the cytochrome p450 self peptide KPIVVLHGY. This cross‐reactivity could promote the rejection of HLA‐B*3501‐positive cells in Epstein–Barr virus‐exposed HLA‐B*0801 recipients. LC13, the dominant TCR against the HLA‐B*0801:FLRGRAYGL complex, fails to recognize HLA‐B*3501:KPIVVLHGY. We report the 1.75‐Angstrom resolution crystal structure of the human allo‐ligand HLA‐B*3501:KPIVVLHGY. Similarities between this structure and that of HLA‐B*0801:FLRGRAYGL may facilitate cross‐recognition by JL12. Moreover, the elevated peptide position in HLA‐B*3501:KPIVVLHGY would provide steric hindrance to LC13, preventing it from interacting in the manner in which it interacts with HLA‐B*0801:FLRGRAYGL. These findings are relevant to understanding the basis of T cell cross‐reactivity in allo‐recognition, optimal transplant donor‐recipient matching and developing specific molecular inhibitors of allo‐recognition.
Immunomodulatory effects associated with a live vaccine against Leishmania major containing CpG oligodeoxynucleotides
Authors: Wu Wenhui , Weigand Luise , Belkaid Yasmine , Mendez Susana 
Published: November 2006

AbstractThe inoculation of live Leishmania major to produce a lesion that heals (leishmanization) is to date the only vaccine against cutaneous leishmaniasis that has proven effective in humans, but it still has an unacceptable frequency of large ulcerating lesions that are slow to heal or, in rare cases, non‐healing. We have previously shown that C57BL/6 mice vaccinated intradermally with 104 L. major/50 µg CpG oligodeoxynucleotides develop little or no dermal lesions and show early containment of parasite growth in the vaccination site, eliminating safety concerns related to the inoculation of live organisms. The addition of CpG to the live vaccine resulted in early activation of dermal dendritic cells and increased IL‐6 production, as well as in a reduction in the accumulation of Foxp3+CD4+CD25+ regulatory T (Treg) cells that naturally occurs in the skin following Leishmania infection. Neutralization of IL‐6 caused the development of larger lesions and increased local Treg cell numbers. Transfer of vaccine‐primed dendritic cells into IL‐6‐deficient mice mitigated lesion development, indicating that IL‐6 reconstitution limited pathology in the vaccination site.
Activation‐induced cell death of human melanoma specific cytotoxic T lymphocytes is mediated by apoptosis‐inducing factor
Authors: Chhabra Arvind , Mehrotra Shikhar , Chakraborty Nitya G. , Dorsky David I. , Mukherji Bijay 
Published: November 2006

AbstractActivation‐induced cell death (AICD) of T cells can be an impediment towards achieving a robust and long‐lived cytolytic T lymphocyte (CTL) response from active specific immunization or after adoptive cell transfer in cancer immunotherapy. The mechanism of AICD in primary CTL, however, remains poorly understood. It is widely believed that AICD is driven by signals from death receptors (DR) and that the cell death takes place in a caspase‐dependent manner, although it has been shown that AICD of T cells can be induced by internal triggers and that death takes place in a caspase‐independent manner. We show here that AICD in human melanoma epitope‐specific primary CTL involves selective mitochondrio‐nuclear translocation of the apoptosis inducing factor (AIF) without cytochrome c release, caspase‐3 and caspase‐8 activation, and results from large‐scale DNA fragmentation. The c‐jun‐N terminal kinase (JNK) inhibitor, SP600125, blocks the mitochondrio‐nuclear translocation of AIF and prevents AICD in these CTL. These findings suggest that the AICD in human melanoma epitope specific primary CTL is mediated by mitochondrial AIF release and JNK is involved in regulation of this death process.
Expression and function of NKG2D in CD4+ T cells specific for human cytomegalovirus
Authors: Sáez‐Borderías Andrea , Gumá Mónica , Angulo Ana , Bellosillo Beatriz , Pende Daniela , López‐Botet Miguel 
Published: November 2006

AbstractThe human NKG2D killer lectin‐like receptor (KLR) is coupled by the DAP10 adapter to phosphoinositide 3‐kinase (PI3 K) and specifically interacts with different stress‐inducible molecules (i.e. MICA, MICB, ULBP) displayed by some tumour and virus‐infected cells. This KLR is commonly expressed by human NK cells as well as TCRγδ+ and TCRαβ+CD8+ T lymphocytes, but it has been also detected in CD4+ T cells from rheumatoid arthritis and cancer patients. In the present study, we analysed NKG2D expression in human cytomegalovirus (HCMV)‐specific CD4+ T lymphocytes. In vitro stimulation of peripheral blood mononuclear cells (PBMC) from healthy seropositive individuals with HCMV promoted variable expansion of CD4+NKG2D+ T lymphocytes that coexpressed perforin. NKG2D was detected in CD28– and CD28dull subsets and was not systematically associated with the expression of other NK cell receptors (i.e. KIR, CD94/NKG2 and ILT2). Engagement of NKG2D with specific mAb synergized with TCR‐dependent activation of CD4+ T cells, triggering proliferation and cytokine production (i.e. IFN‐γ and TNF‐α). Altogether, the data support the notion that NKG2D functions as a prototypic costimulatory receptor in a subset of HCMV‐specific CD4+ T lymphocytes and thus may have a role in the response against infected HLA class II+ cells displaying NKG2D ligands.
Synthesis and Structure of [nPr3N(CH2)6NnPr3][CuFe3Br3(SePh)6], [Cu5Fe(SePh)7(PPh3)4] and [Cu4Fe3(SePh)10(PPh3)4]
Authors: Eichhöfer Andreas , Fenske Dieter , Olkowska‐Oetzel Jolanta 
Published: November 2006

AbstractCuBr and Fe(OOCCH3)2 react with PhSeSiMe3 in acetonitrile in the presence of the diammonium salt [nPr3N(CH2)6NnPr3]Br2 to yield ionic [nPr3N(CH2)6NnPr3][CuFe3Br3(SePh)6]. The neutral complexes [Cu5Fe(SePh)7(PPh3)4] and [Cu4Fe3(SePh)10(PPh3)4] were obtained by similar reactions of different stoichiometric mixtures of CuOOCCH3 and FeCl2 with PPh3 and PhSeSiMe3. The crystal structures of the compounds were determined by single‐crystal X‐ray analysis to give new structural types of molecular cluster compounds formed by copper, iron and selenium. Thermal treatment of [Cu5Fe(SePh)7(PPh3)4] and [Cu4Fe3(SePh)10(PPh3)4] resultsin the formation of mixtures of binary Cu2Se and ternaryCuFeSe2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Crystal Structure of Three Carborane Complexes, [M{7,8‐(OPPh2)2‐7,8‐C2B9H10}2] (M = Cu, Zn) and [Ni(thf){7,8‐(OPPh2)2‐7,8‐C2B9H10}2]·thf, and Two Carborane Compounds, 1‐(OPPh2)‐2‐(PPh2)‐1,2‐C2B10H10 and H[7,8‐(OPPh2)2‐7,8‐C2B9H10]·0.25C2H5OH
Authors: Dou Jianmin , Zhang Daopeng , Li Dacheng , Wang Daqi 
Published: November 2006

AbstractThree new carborane complexes containing the bis(phosphoryl)‐nido‐carborane ligand, [Cu{7,8‐(OPPh2)2‐7,8‐C2B9H10}2] (1), [Zn{7,8‐(OPPh2)2‐7,8‐C2B9H10}2] (2), and [Ni(thf){7,8‐(OPPh2)2‐7,8‐C2B9H10}2]·thf (3), were synthesized by the reactions of 1,2‐(PPh2)2‐1,2‐C2B10H10 with CuCl2·2H2O, ZnCl2, and NiCl2·6H2O, respectively, in ethanol in air. Two other compounds, 1‐(OPPh2)‐2‐(PPh2)‐1,2‐C2B10H10 (4) and H[7,8‐(OPPh2)2‐7,8‐C2B9H10]·0.25C2H5OH (5), were also obtained through the oxidation of the closo ligand in air. All new compounds were characterized by elemental analysis, FT‐IR, 1H and 13C NMR spectroscopy, and single‐crystal X‐ray diffraction. In complexes 1 and 2, the metal atoms are coordinated to the four oxygen atoms of the two bidentate bis(phosphoryl) ligands [7,8‐(OPPh2)2‐7,8‐C2B9H10]– and adopt a square‐planar geometry. For complex 3, the molecular structure reveals that the geometry at the nickel atom is square‐pyramidal, with four oxygen atoms from the four OPPh2 groups and one additional one from a thf molecule. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The Transient Titanocene(II): Direct Synthesis from Solvated Titanium(II) Chloride and Cyclopentadienylsodium and Ensuing Interception with Diphenylacetylene as 1,1‐Bis(cyclopentadienyl)‐2,3,4,5‐tetraphenyltitanacyclopentadiene
Authors: Eisch John J. , Adeosun Adetenu A. , Birmingham John M. 
Published: November 2006

AbstractFor the first time the unstable titanocene(II) has been directly synthesized by the Wilkinson metallocene approach, namely the interaction of a THF‐soluble form of titanium(II) chloride with two equivalents of cyclopentadienylsodium in THF solution at 0°–25 °C. Because of the transient existence of the titanocene(II) thereby obtained, it could only be chemically trapped in high yield as 1,1‐bis(cyclopentadienyl)‐2,3,4,5‐tetraphenyltitanacyclopentadiene by two equivalents of diphenylacetylene, if the acetylene was added at 25 °C, without removal of the by‐product LiCl and NaCl. If the addition of the acetylene was delayed, in order to filter off the LiCl and NaCl from the reaction mixture, then no trace of the titanacyclopentadiene derivative was found upon hydrolytic workup. Instead, a significant portion of the acetylene was found to have undergone hydrotitanation. This finding is clear evidence that the titanocene(II) had undergone a precedented rearrangement to a known dimer having the structure of a titanocene(III) hydride with a fulvalene bridge between the titanium centers. We suggest that the LiCl and NaCl present in the unfiltered reaction mixture form a dichloro complex with titanocene(II) and thereby retard its dimerizing rearrangement to the titanocene(III) hydride. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Competing Radical and Non‐Radical Pathways for the Decomposition of LFeII(H2O2) Complexes: a Density Functional Study
Authors: Anastasi Anna E. , Lienke Achim , Comba Peter , Rohwer Heidi , McGrady John E. 
Published: November 2006

AbstractDensity functional theory has been used to explore the mechanism of hydrogen peroxide decomposition when coordinated to a bispidone iron(II) complex. Two quite distinct pathways are identified, one involving O–O bond homolysis followed by a “rebound” hydrogen atom abstraction, the other involving proton transfer followed by O–O bond heterolysis. A water molecule in the second coordination sphere plays a key role in both pathways. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Characterisation of WVI Complexes of Phosphane Oxide Ligands, [WO2X2(OPR3)2] (X = F, Cl or Br; R = Me or Ph), and of the [MoO2F2(OPR3)2]
Authors: Davis Martin F. , Levason William , Ratnani Raju , Reid Gillian , Rose Tim , Webster Michael 
Published: November 2006

AbstractPhosphane oxide complexes of dioxidotungstenVI, [WO2X2(OPR3)2] (X = Cl or Br, M = Ph or Me) have been prepared under anhydrous conditions from the reaction of WX6 with (Me3Si)2O in CH2Cl2, followed by addition of OPR3. Some diphosphane dioxide analogues have been made similarly, viz, [WO2X2(L–L)] {L–L = Ph2P(O)(CH2)nP(O)Ph2 (n = 1 or 2), o‐C6H4[P(O)Ph2]2}. The complexes have been characterised by elemental analysis, IR and NMR (1H and 31P{1H}) spectroscopy, and the structures of [WO2Br2(OPPh3)2] and [WO2Cl2(OPMe3)2] determined, revealing distorted six‐coordinate tungsten centres with cis‐WO2 and trans‐WX2 units. The difluorido‐dioxido complexes [MO2F2(OPR3)2] (M = Mo or W) and [WO2F2(L′–L′)] (L′–L′ = 2,2′‐bipyridyl, 1,10‐phenanthroline) have been prepared by fluorination of the corresponding chlorido complexes with Me3SnF in CH2Cl2. These are characterised similarly and by 19F{1H} NMR spectroscopy. Attempts to make [MO2I2(OPR3)2] were unsuccessful. No adduct formation occurs between CrO2Cl2 and OPPh3 under rigorously anhydrous conditions. Crystal structures of [Me3SnCl(OPPh3)] and two forms of [WO2Cl2(1,10‐phen)] are also reported and discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Valence‐State Distribution in the Ruthenium o‐Quinonoid Systems [Ru(trpy)(Cl)(L1)]+ and [Ru(trpy)(Cl)(L2)]+ (L1 = o‐Iminobenzoquinone, L2 = o‐Diiminobenzoquinone; trpy = 2,2′:6′,2″‐Terpyridine)
Authors: Maji Somnath , Patra Srikanta , Chakraborty Saumen , Janardanan Deepa , Mobin Shaikh M. , Sunoj Raghavan B. , Lahiri Goutam Kumar 
Published: November 2006

AbstractValence‐state distributions in the ruthenium quinonoid (L) frameworks of [Ru(trpy)(Cl)(L1)]ClO4 (1‐ClO4) and [Ru(trpy)(Cl)(L2)]ClO4 (2‐ClO4) (L1 = o‐iminobenzoquinone, L2 = o‐diiminobenzoquinone, and trpy = 2,2′:6′,2″‐terpyridine) have been examined by structural, spectroelectrochemical, and density functional studies. The structural data, in corroboration with the DFT‐calculated bond lengths, suggest that the primary valence formulation of 1+ and 2+ is a spin‐coupled singlet configuration of [RuIII(trpy)(Cl)(LSq)]+ with a minority contribution from diamagnetic [RuII(trpy)(Cl)(LQ)]+. Consequently, the closely spaced successive two oxidation processes of 1+ and 2+ can be assigned to RuIII→RuIV and LSq→LQ, which involve the HOMO and HOMO–3 levels, respectively. The one‐electron‐oxidized species 12+ and 22+ display sharp EPR signals with g values of 2.011 and 2.014 at 77 K, respectively. The free radical EPR signal (g ≈ 2.0) of the one‐electron‐reduced species 1 or 2 signifies the preferential involvement of the ruthenium‐based orbitals in the first reduction process to yield [RuII(trpy)(Cl)(LSq)], although the LUMO is calculated to be a mixture of dπ(Ru) (≈24 %) and π*(L) (≈ 70 %). The subsequent second (1–/2–) and third (12–/22–) reduction steps in each case are associated simply with the terpyridyl‐based orbitals (≥90 %). The lowest energy charge‐transfer transitions of 1+ and 2+ at 556 and 509 nm are predicted to be HOMO → LUMO+1 and HOMO–1 → LUMO+1 transitions, respectively. In the successive oxidations 1+/2+ → 12+/22+ → 13+/23+ the lowest energy charge‐transfer transitions undergo a blue shift with a substantial reduction in intensity. The lowest energy charge‐transfer transitions, however, are red shifted with a reduction in intensity on going from (1+/2+) to 1/2. The origin of the transitions in the 12+/22+ and 1/2 systems is predicted by TDDFT analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Resonance Raman Spectroscopy with Overtones Involving Metal‐Ligand and Ligand‐Centered Modes in (o‐Benzoquinonediimine)ruthenium(II) Complexes
Authors: Beaulac Rémi , Lever A. B. P. , Reber Christian 
Published: November 2006

AbstractResonance Raman spectra of (o‐benzoquinonediimine)ruthenium(II) complexes measured with visible excitation wavelengths show distinct resonance enhancements and intense overtone and combination bands. Assignments of the most prominent fundamental bands are made on the basis of comparisons with theoretical spectra obtained from DFT calculations. Excited state distortions are determined from the resonance Raman intensities and lead to calculated luminescence and absorption spectra in good agreement with experiment. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Bonding Properties Related with Chiral Discrimination in Dinuclear Metal Complexes of Group 10
Authors: Picazo Oscar , Alkorta Ibon , Elguero José , Sundberg Markku R. , Valo Jaana 
Published: November 2006

AbstractA series of neutral dinuclear homo‐ and heterochiral complexes formed by hydrazine (a molecule with axial chirality), a metal atom of group 10 (Ni, Pd, Pt), and halogen atoms (F, Cl, Br, I) was studied by computational methods including density functional theory. In the optimized structures the heterochiral complexes were always found to be energetically favored. The chiral discrimination depends on the contributions coming from the metal atoms and the halogen anions attached to them. Moreover, the relative energies of the optimized complexes are correlated with the electronegativity of the metals and the halogens as well as with the relative distances of the bond critical points in the metal–nitrogen bonds. Also the smaller deviation of the ligand–metal–ligand angles from the ideal value of 90° corresponds to the heterochiral complexes. An analysis of the bonding properties reveals a complex mechanism for the behavior of the electron lone pairs of the nitrogen and halogen atoms. The electronic properties of the optimized complexes were studied by NBO (Natural Bond Orbital) and QTAIM (Quantum Theory of Atoms in Molecules) methods. An NBO analysis of the energy differences between the stabilizing energies related to the interactions between an electron lone pair of the coordinated nitrogen atom and the opposite M–X antibonding orbital explain the differences of the total energies between the diastereomeric heterochiral and homochiral complexes. The stabilizing energies have systematically more negative values in the heterochiral complexes; this can be interpreteted as a measure of the trans influence. Small energy values related to the cis influence were found mainly in the nickel complexes. The M–N bonds in the heterochiral complexes are more polar with a higher bond order than that in the homochiral ones, as shown by QTAIM methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The Poly(Radical Cation) of a Star‐Shaped Oligoarylamine — Detection of Excited High‐Spin States
Authors: Hirao Yasukazu , Ishizaki Haruya , Ito Akihiro , Kato Tatsuhisa , Tanaka Kazuyoshi 
Published: November 2006

AbstractThe intramolecular spin–spin interaction in the highly oxidized species of a star‐shaped oligoarylamine, namely hexakis{4‐[bis(p‐methoxyphenyl)amino]phenyl}benzene (1), in which six diphenylamine units are introduced as redox‐active sites into a central hexaphenylbenzene core, has been investigated by EPR spectroscopy. The hexacation‐rich sample was prepared by chemical oxidation with 7.5 equivalents. of [bis(trifluoroacetoxy)iodo]benzene (PIFA) in the presence of 10 vol.‐% trifluoroacetic acid (TFA) in dichloromethane at 195 K. Variable‐temperature EPR measurements provided the non‐Curie temperature dependence of the signal intensity. The fine structure of the EPR spectrum also varies with temperature. In order to identify the spin multiplicity of the generated poly(radical cation), we carried out electron spin transient nutation (ESTN) measurements based on pulsed EPR spectroscopy at various temperatures. From the ESTN spectra, it was found that the high‐spin states are thermally populated with increasing temperature. These results indicate the low‐spin ground state of the poly(radical cation) of 1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)