Magnetic "Molecular Oligomers" based on decametallic supertetrahedra: A giant Mn49 cuboctahedron and its Mn25Na4 fragment

et al.Two nanosized Mn and MnNa clusters based on analogues of the high-spin (S=22) [Mn Mn (μ-O)] supertetrahedral core are reported. Mn and MnNa complexes consist of eight and four decametallic supertetrahedral subunits, respectively, display high virtual symmetry (O), and are unique examples of clusters based on a large number of tightly linked high nuclearity magnetic units. The complexes also have large spin ground-state values (Mn: S=61/2; MnNa: S=51/2) with the Mn cluster displaying single-molecule magnet (SMM) behavior and being the second largest reported homometallic SMM.This work was supported by the Cyprus Research Promotion Foundation grant ANABAVMISH/PAGIO/0308/12 which is co-funded by the Republic of Cyprus and the European Regional Development Fund, the US National Science Foundation (Grant DMR-1213030 to G.C.), and the Spanish MINECO (Project FEDER-MAT2012-38318-C03-01).Peer Reviewe

Synthesis and Structural Characterization of a Metal Cluster and a Coordination Polymer Based on the [Mn6(μ4-O)2]10+ Unit

A new 1-D coordination polymer {[Mn6O2(O2CMe)10(H2O)4]·2.5H2O}∞ (1·2.5H2O)∞ and the cluster [Mn6O2(O2(O2CPh)10 (py)2(MeCN)(H2O)]·2MeCN (2·2MeCN) are reported. Both compounds were synthesized by room temperature reactions of [Mn3(μ3-O)(O2CR)6(L)2(L′)] (R = Me, L = L′ = py, (1·2.5H2O)∞; R = Ph, L = py, L′ = H2O, 2·2MeCN) in the presence of 3-hydroxymethylpyridine (3hmpH) in acetonitrile. The structures of these complexes are based on hexanuclear mixed-valent manganese carboxylate clusters containing the [Mn4IIMn2III(μ4-O)2]10+ structural core. (1·2.5H2O)∞ consists of zigzag chain polymers constructed from [Mn6O2(O2CMe)10(H2O)4] repeating units linked through acetate ligands, whereas 2·2MeCN comprises a discrete Mn6-benzoate cluster

Synthesis and Characterization of a Linear [Mn3(O2CMe)4(py)8]2+ Complex

Two new compounds that consist of the linear trinuclear manganese(II) cation [Mn3(O2CMe)4(py)8]2+ cocrystallizing with different counteranions (I3−, [1]; ClO4−, [2]) are reported. Complex 1 was prepared from the reaction of [Mn(O2CMe)2] · 4H2O with I2 in MeCO2H/py, whereas complex 2 was isolated from the reaction of [Mn3O(O2CMe)6(py)3] · py with [Mn(ClO4)2] · 6H2O in MeCN/py. The crystal structures of both compounds were determined by single crystal X-ray crystallography. Magnetic susceptibility studies that were performed in microcrystalline powder of 1 in the 2–300 K range revealed the presence of antiferromagnetic exchange interactions that resulted in an S = 5/2 ground spin state

Bismuth(III) bromide-thioamide complexes: synthesis, characterization and cytotoxic properties

New bismuth(III) bromine compounds of the heterocyclic thioamides were prepared and structurally characterized. The reaction of heterocyclic thioamides with bismuth(III) bromide resulted in the formation of the {[BiBr2(mu(2)-Br)(MMI)(2)](2)center dot CH3COCH3 center dot H2O} (1), {[BiBr2(MBZIM)(4)]center dot Br center dot 2H(2)O} (2), {[BiBr2(mu(2)-Br)(tHPMT)(2)](2)center dot CH3CN} (3), {[BiBr2(mu(2)-Br)(PYT)(2)](2)center dot CH3CN} (4) and {[BiBr2(mu(2)-Br)(MBZT)(2)](2) 2CH(3)OH} (5) complexes (MMI: 2-mercapto-1-methylimidazole, MBZIM: 2-mercaptobenzimidazole, tHPMT: 2-mercapto-3,4,5,6-tetrahydro-pyrimidine, PYT: 2-mercaptopyridine and MBZT: 2-mercaptobenzothiazole). The complexes 1-5 were characterized by melting point (m.p.), elemental analysis (c.a.), molar conductivity, Fourier-transform infrared (FT-IR), Fourier-transform Raman (FT-Raman), nuclear magnetic resonance (H-1 and (CNMR)-C-13) spectroscopy, UV-Vis spectroscopy and thermogravimetric-differential thermal analysis (TG-DTA). The molecular structures of 1-5 were determined by single-crystal X-ray diffraction. Complex 2 is a first ionic monomuclear octahedral bismuth(III) bromide, while the complexes 1,3-5 are the first examples of dinuclear bismuth(III) bromide derivatives. Complexes 1-5 were evaluated in terms of their in vitro cytotoxic activity against human adenocarcinoma breast (MCF-7) and cervix (HeLa) cells. The toxicity on normal human fetal lung fibroblast cells (MRC-5) was also evaluated. Moreover, the complexes 1-5 and free heterocyclic thioamide ligands were studied upon the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX).Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114Z457](a) I.I.O. and M.C. acknowledge the financial support from The Scientific and Technological Research Council of Turkey (TUBITAK, Project No. 114Z457). (b) CNB and SKH would like to thank the Unit of Bioactivity Testing of Xenobiotics of the University of Ioannina for providing access to their facilities. (c) The International Graduate Program in 'Biological Inorganic Chemistry', which operates at the University of Ioannina within the collaboration of the Departments of Chemistry of the Universities of Ioannina, Athens, Thessaloniki, Patras, Crete and the Department of Chemistry of the University of Cyprus (http://bic.chem.uoi.gr/BIC-En/index-en.html), is acknowledged for the stimulating discussion forum

Giant Heterometallic [Mn36Ni4]0/2− and [Mn32Co8] “Loops-of-Loops-and-Supertetrahedra” Molecular Aggregates

We report the synthesis, crystal structures and magnetic properties of the giant heterometallic [Mn36Ni4]2−/0 (compounds 1, 2)/[Mn32Co8] (compound 3) “loops-of-loops-and-supertetrahedra” molecular aggregates and of a [Mn2Ni6]2+ compound (cation of 4) that is structurally related with the cation co-crystallizing with the anion of 1. In particular, after the initial preparation and characterization of compound [Mn2Ni6(μ4-O)2(μ3-OH)3(μ3-Cl)3(O2CCH3)6(py)8]2+[Mn36Ni4(μ4-O)8(μ3-O)4(μ3-Cl)8Cl4(O2CCH3)26(pd)24(py)4]2− (1) we targeted the isolation of (i) both the cationic and the anionic aggregates of 1 in a discrete form and (ii) the Mn/Co analog of [Mn36Ni4]2− aggregate. Our synthetic efforts toward these directions afforded the discrete [Mn36Ni4] “loops-of-loops-and-supertetrahedra” aggregate [Mn36Ni4(μ4-O)8(μ3-O)4(μ3-Cl)8Cl2(O2CCH3)26(pd)24(py)4(H2O)2] (2), the heterometallic Mn/Co analog [Mn32Co8(μ4-O)8(μ3-O)4(μ3-Cl)8Cl2(μ2-OCH2CH3)2(O2CCH3)28(pd)22(py)6] (3) and the discrete [Mn2Ni6]2+ cation [Mn2Ni6(μ4-O)2(μ3-OH)4(μ3-Cl)2(O2CCH3)6(py)8](ClO4)(OH) (4). The structure of 1 consists of a mixed valence [Mn28IIIMn8IINi4II]2− molecular aggregate that contains two Mn8IIINi2II loops separated by two Mn6IIIMn4II supertetrahedral units and a [Mn2IIINi6II]2+ cation based on two [MnIIINi3II(μ4-O)(μ3-OH)1.5(μ3-Cl)1.5]4+ cubane sub-units connected through both mono- and tri-atomic bridges provided by the μ4-O2− and carboxylate anions. The structures of 2–4 are related to those of the compounds co-crystallized in 1 exhibiting however some differences that shall be discussed in detail in the manuscript. Magnetism studies revealed the presence of dominant ferromagnetic interactions in 1–3 that lead to large ground state spin (ST) values for the “loops-of-loops-and-supertetrahedra” aggregates and antiferromagnetic exchange interactions in 4 that lead to a low (and possibly zero) ST value. In particular, dc and ac magnetic susceptibility studies revealed that the discrete [Mn36Ni4] aggregate exhibits a large ST value ~ 26 but is not a new SMM. The ac magnetic susceptibility studies of the [Mn32Co8] analog revealed an extremely weak beginning of an out-of-phase tail indicating the presence of a very small relaxation barrier assignable to the anisotropic Co2+ions and a resulting out-of-phase ac signal whose peak is at very low T

A hexameric [MnIII18Na6] wheel based on [MnIII3O]7+ sub-units

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A flexible Cd2+ metal organic framework with a unique (3,3,6)-connected topology, unprecedented secondary building units and single crystal to single crystal solvent exchange properties

A new flexible Cd2+ metal organic framework (MOF), denoted as UCY-3, which is the second example of a MOF with the ligand H3CIP [H3CIP = 5-(4-carboxybenzylideneamino)isophthalic acid], is reported. It shows a unique (3,3,6)-connected topology and is based on a neutral non-oxo triangular [Cd-3(COO)(6)] secondary building unit that appears for the first time in MOFs chemistry. UCY-3 displays significant structural flexibility, capability for exchange of the guest solvents by various organic molecules in a single-crystal-to-single-crystal fashion as well as breathing capacity allowing the incorporation of relatively large amount of benzene into its pores. Overall this work indicates that MOFs based on semi-rigid polytopic ligands may adopt unprecedented structural types and exhibit unexpectedly high absorption capacities for relatively bulky organic molecules, as a result of their flexibility and breathing capability

Insertion of Functional Groups into a Nd3+ Metal-Organic Framework via Single-Crystal-to-Single-Crystal Coordinating Solvent Exchange

Single-crystal-to-single-crystal (SCSC) transformations represent some of the most fascinating phenomena in chemistry. They are not only intriguing from a basic science point of view but also provide a means to modify or tune the properties of the materials via the postsynthetic introduction of suitable guest molecules or organic functional groups into their structures. Here, we describe UCY-2, a new flexible Nd3+ metal-organic framework (MOF), which exhibits a unique capability to undergo a plethora of SCSC transformations with some of them being very uncommon. These structural alterations involve the replacement of coordinating solvent molecules of UCY-2 by terminally ligating solvents and organic ligands with multiple functional groups including -OH, -SH, -NH-, and -NH2 or their combinations, chelating ligands, anions, and two different organic compounds. The SCSC coordinating solvent exchange is thus demonstrated as a powerful method for the functionalization of MOFs