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and Aris Terzis

Bio: and Aris Terzis is an academic researcher from Aristotle University of Thessaloniki. The author has contributed to research in topics: Crystal structure & Denticity. The author has an hindex of 13, co-authored 13 publications receiving 546 citations. Previous affiliations of and Aris Terzis include Paul Sabatier University & University of Patras.

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TL;DR: In this article, the synthesis, crystal structure, and properties of [MnII(MCPA)2(H2O)2]n (MCPA = 2-methyl-4-chlorophenoxyacetic acid), a 2-D manganese carboxylato polymer is reported.
Abstract: The synthesis, crystal structure, and properties of [MnII(MCPA)2(H2O)2]n (MCPA = 2-methyl-4-chlorophenoxyacetic acid), 1, a 2-D manganese carboxylato polymer is reported. The synthesis of 1 has been achieved via the reaction of MCPA with MnCl2·2H2O and NaHCO3 in methanol. Crystal structure data: [C18H20Cl2O8Mn]; orthorhombic; space group Pbca; a = 7.811(6) A; b = 34.67(3) A; c = 7.481(6) A; Z = 4. The compound has a two-dimensional structure with Mn2+ atoms in an octahedral environment and mixed water/carboxylate coordination. The metal atoms are segregated in planes which are perpendicular to the b axis and are spaced 17.73 A apart. Variable-temperature magnetic susceptibility measurements indicate the presence of antiferromagnetic behavior. The EPR spectra of polycrystalline samples at 4 K show that the intensity of the signal decreases significantly with decreasing temperature and below ∼4 K becomes EPR silent.

117 citations

Journal ArticleDOI
TL;DR: The synthetic route of partially beta-halogenated via a "metal-assisted" reaction and perhalogenate terbium complexes is described and the novel crystal structure of the Ni(Cl(8)TPP) is discussed in great detail and compared with the previously reported structures.
Abstract: The synthetic route of partially ‚-halogenated via a “metal-assisted” reaction and perhalogenated terbium complexes is described. This protocol allows the facile insertion of the halogens (bromines or chlorides) to the porphyrin peripheral positions. The electronic absorption spectra and the redox potentials of the free porphyrins as well as the terbium complexes are dramatically affected as the number of halogen atoms increase. In fact, two antagonistic effects are responsible for that, the inductive and the distortion effects on the porphyrin ring. They result in a red shift for the Soret band and a stabilization/destabilization of the HOMOs/LUMOs which in turn is manifested by variations on the redox potentials. The novel crystal structure of the Ni(Cl8TPP) is discussed in great detail and compared with the previously reported structures of Tb(Cl8TPP) (OAc)(DMSO)2‚3PhCH3‚MeOH and H2(Br8TPP), as well as with other perhalogenated nickel porphyrins available in the literature.

71 citations

Journal ArticleDOI
TL;DR: The octanuclear cluster Zn(8)(shi)(4)(pko)(4) contains a 12-membered tetranuclear metallacrown core constructed by four Zn metal atoms and four shi(3-) ligands that can be described as having the formally anionic [12-MC(Zn(II)N(shi))-4](4-) core.
Abstract: Interaction of ZnCl2 with Hpko (Hpko, di-2-pyridyl-ketonoxime) results in the formation of a uninuclear Zn(Hpko)Cl2 (1) compound or in a 12-membered tetranuclear metallacrown (OH)2[inv12-MCZn(II)N(pko)-4]Cl2 (2) depending on the pH of the mother solution. The addition of H3shi (H3shi, salicylhydroxamic acid) leads to the formation of the octanuclear 12-membered tetranuclear metallacrown [Zn2]{[Zn2(pko)4][12-MCZn(II)N(shi)-4](CH3OH)2} (3). The metallacrown core of 2 is characterized as “inverse” because the zinc atoms, rather than oxygen atoms, are oriented toward the central cavity. Two triply bridging hydroxides are accommodated in the center of the metallacrown ring. The pko- ligands form a propeller configuration that imposes absolute stereoisomerism with Λ and Δ chirality. Each hydroxo oxygen bridges two octahedral zinc atoms and a tetrahedral one. The octanuclear cluster Zn8(shi)4(pko)4(CH3OH)2 contains a 12-membered tetranuclear metallacrown core constructed by four Zn metal atoms and four shi3- lig...

62 citations

Journal ArticleDOI
TL;DR: The first documentation of syn/anti isomerism in N-substituted TcO[SN(R)S][S] mixed-ligand complexes is reported, which was formed in high yield and isolated as a crystalline product.
Abstract: A series of 22 mixed-ligand complexes of the general formula TcOL1L2, where L1H2 are N-substituted bis(2-mercaptoethyl)amine ligands, [SN(R)S], and L2H are monodentate thiols as coligand, is report...

57 citations

Journal ArticleDOI
TL;DR: The first example of a copper-II polymer having a tetrameric repeating unit with S = 2 ground state is reported in this paper, where the synthesis of compound 1 has been achieved via the reaction of CuCl2 with dpk in methanol.
Abstract: The synthesis, crystal structure and properties of the compound [Cu4(dpk·CH3O)2Cl6]n (dpk·CH3OH = unimethylated diol of di-2-pyridyl ketone) (1), the first example of a copper(II) polymer having a tetrameric repeating unit with S = 2 ground state is reported. The synthesis of compound 1 has been achieved via the reaction of CuCl2 with dpk in methanol. The base-catalyzed addition results in the formation of a unimethylated diol which may deprotonated. Crystal structure data: [C12H11N2O2Cl3Cu2], Mr = 448.68; triclinic; space group P1; a = 7.800(1) (A); b = 8.946(1) (A); c = 13.383(1) (A); α = 118.964(3)°; β = 92.693(3)°; γ = 66.824(3)°; Z = 2. Variable temperature magnetic susceptibility measurements indicate the presence of a ferromagnetic behavior with antiferromagnetic coupling below 15 K. The best fit parameters obtained from this model are J1 = 71.32 cm-1, J2 = 1.43 cm-1, J3 = 0.07 cm-1, J4 = 0 (fixed), zJ = −0.553 cm-1, and g = 2.1 (fixed). The energy levels obtained from the fitting procedure show ...

53 citations


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TL;DR: A hybrid density functional theory has been utilized to put forward a triangular Mn moiety closely coupled by μ-oxo groups as a potential model for the WO site and another mechanism incorporating a “C-shaped” cluster has also been suggested recently.
Abstract: ion model is not a true H-abstracting process but rather a special case of proton-coupled electron transfer where reduction of YZ by the Mn4 cluster occurs with the proton emanating from solvent water. These two theories will now be described briefly. A hydrogen atom abstraction process by the YZ residue in conjunction with a dimer-of-dimers structural template has led to an interesting hypothesis wherein an O atom is proposed as a terminal ligand to Mn (see Figure 8 (top)).175,188 The Clion is proposed to migrate in S1 to S2 and S2 to S3 state transitions while YZ serves as the H atom abstractor and Ca2+ ion binds to Clin the lower S states. In another proposal two dinuclear Mn complexes perform diverse functions: one oxidizes H2O to peroxide while the other converts peroxide to water.16,189-191 The final O-O bond forming step in the S4 state is predicted to result from attack of the hydroxo group bound to Ca2+ to a strongly electrophilic MnVdO species. In a similar hypothesis, a Clbridging between a Mn and a Ca2+ is responsible for modulating the nucleophilic attack of the hydroxide ion.181,192 This was first predicted from mass spectrometric studies.176 The product of this step has been argued to be similar to the ferric hydroperoxide in oxyhemerythrin. Oxygen release is envisioned in a manner similar to that of oxyhemerythrin concomitant with reduction of Mn and protonation of μ-oxo bridges.192 On the basis of XAS and EPR data, another mechanism incorporating a “C-shaped” cluster has also been suggested recently involving one redox-active Mn per [Mn2(μ-O)2] dimeric moiety (see Figure 8 (bottom)).17,193,194 Here, the O-O bond is formed between an oxyl radical and a μ-oxo atom. A hybrid density functional theory has been utilized to put forward a triangular Mn moiety closely coupled by μ-oxo groups as a potential model for the WO site. The previously suggested oxyl radical mechanism14 has been reexamined in this work with an oxyl radical placed in a bridging fashion between two Mn atoms. Consistent with earlier studies, only one Mn is redox active in this model and the Ca2+ ion has been shown as playing the role of a bridging metal Manganese Clusters with Relevance to Photosystem II Chemical Reviews, 2004, Vol. 104, No. 9 3991

533 citations

Journal ArticleDOI
TL;DR: Recent advances in the study of the Oxygen Evolving Complex (OEC) of Photosystem II (PSII) include structural information attained from several X-ray crystallographic and spectroscopic investigations that offer better insight into the possible pathways used by PSII to drive photosynthetic water oxidation catalysis.

322 citations

Journal ArticleDOI
TL;DR: The coordination chemistry of pyridyl oximes is reviewed in this paper, with emphasis on structural features and physical properties (mainly magnetic properties) of the resulting metal complexes.

299 citations