294 research outputs found
Iron(III)-pivalate-based complexes with tetranuclear {Fe4(?3-O)2}8+ cores and n-donor ligands: formation of cluster and polymeric architectures
No full textDifferent synthetic routes have been used for the preparation of a new tetranuclear [Fe4O2(O2CCMe3)(8)(bpm)] cluster (1) and a one-dimensional coordination polymer [Fe4O2-(O2CCMe3)(8)(hmta)](n) (2) (bpm = 2,2'-bipyrimidine and hmta = hexamethylenetetramine). For cluster 1, two structural isomers, 1a and 1b center dot 3MeCN, have been found. X-ray crystallographic analysis showed that all complexes consist of a central {Fe-4(mu(3)-O)(2)}(8+) core. In 1a, metal ions in the core are additionally linked by six bridging pivalates as two other pivalates and a bpm ligand are chelated to Fe-III ions, whereas in cluster 1b, metal ions in the {Fe-4(mu(3)-O)(2)}(8+) core are linked by seven bridging pivalates and only one carboxylate as well as bpm are chelated to the iron centers. In coordination polymer 2, [Fe4O2(O2CCMe3)(8)] clusters are bridged by hmta ligands to form zigzag chains. Magnetic measurements have been carried out to characterize these complexes and revealed antiferromagnetic interactions between Fe-III ions with best-fit parameters of J(wb) = -72.2 (1a) and -88.7 cm(-1) (1b) for wing...body interactions
Aggregation of a Giant Bean-like {Mn 26 Dy 6 } Heterometallic Oxo-Hydroxo-Carboxylate Nanosized Cluster from a Hexanuclear {Mn 6 } Precursor
No full textStarting from a well-known hexanuclear mixed-valent manganese cluster, we report a synthetic protocol for its extension toward very large 3d-4f clusters. The exemplary case study demonstrates that a combination of such Mn6 clusters with a DyIII salt and an auxiliary triazine-type ligand yields a large bean-like, heterometallic dotriacontanuclear mixed-valent nanocluster [Mn26Dy6O16(OH)12(O2CCHMe2)42]. This compound, which possesses a molecular C2 symmetry and crystallizes in a dense packing arrangement without inclusion of solvents, comprises 16 MnIII, 10 MnII, and 6 DyIII ions, thus leading to a plurality of intracluster magnetic exchange interactions. Interestingly, this results in the highest-nuclearity Mn-Dy cluster that shows a single-molecule magnetic (SMM) behavior
Versatility of Cyclic Triimidazole to Assemble 1D, 2D, and 3D Cu(I) Halide Coordination Networks
No full textCyclic triimidazole (C 9 H 6 N 6 , L), with C 3h molecular symmetry and three nitrogen atoms available for coordination, is here successfully employed for the first time in the synthesis of coordination compounds. In particular, by varying the reaction conditions (e.g., solvent, temperature, template), seven Cu(I)-halide coordination polymers of different dimensionality are obtained: two 1D polymers, [CuIL] n (1) and [CuIL]·(I 2 ) 0.5 n (2), three 2D nets, [CuXL] n (X = I, Br) (3-5), and two 3D networks, [CuClL] n (6) and [Cu 3 L 4 ]I 3 n (7). Single crystal X-ray diffraction analysis reveals that the structural versatility of both the ligand and the CuX moiety allows isolating 1D double-stranded stairs in which L is monodentate, 2D layers containing either Cu 2 (μ-X) 2 or Cu 2 (μ-X) moieties and bidentate L ligands, 3D frameworks built up by tridentate L linkers and either monodentate or noncoordinating halogen atoms. The 3D frameworks show nets of srs and bor topologies. The SHG efficiency of powders of 7 (the only noncentrosymmetric derivative of the series) is 10 times higher than that of sucrose. Phosphorescent emission of XLCT character is observed for 1 and 6
Tressler - Victor G. A. Tressler
No full textA.B.; A.M., 1889; salutatorian; entered sophomore class; Phi Gamma Delta. B.D., McCormick Sem., Chicago, Ill., 1891; D.D., Susquehanna U., 1904; Ph.D., Leipsig U., Germany, 1901. Born April 10, 1865. Lutheran clergyman, San Jose, Cal., 1891-99; graduate student, Berlin, Leipsig and Paris, 1899-1902; dean and prof., Ansgar C., Minnesota, 1902-03; prof., Hamma Divinity School, 1905-23. Pres. of Gen. Synod of Evan. Luth. Ch., 1917-23; author of various monographs and contributor to religious publications. Died in 1923. Married 1906, Mary Baugher Gotwald. Handwritten on back: ""Compliments of your friend and classmate, Victor G A Tressler, Peabod[y] Kansas, July 27-86, ""Post-laborem Praemium."
Persistent CH···π Interactions in Mefenamic Acid Complexes with Cyclic and Acyclic Amines
No full textInteraction of mefenamic acid [2-(2,3-dimethylphenyl)aminobenzoic acid, maH] with piperazine (ppz), 1,4,7,10-tetraazacyclododecane (cyclen), meso-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (teta), and tris(hydroxymethyl)aminomethane (tris) resulted in crystalline proton-transfer complexes of the compositions (ppzH2)(ma)2·4H2O 1, (cyclenH2)(ma)2·2H2O 2, (tetaH2)(ma)2·2H2O 3, and (trisH)(ma)·H2O 4. Immediate cation−anion hydrogen bonds and those mediated by water molecules are the prime driving forces for the maH and amine assembly. Persistent CH···π interactions involving the aromatic rings were found to play an important role in the formation of final structures. All complexes reveal the pronounced segregation of hydrophilic and hydrophobic regions
Stimuli-Responsive Photoluminescence of Eu(III) Complexes with Triazine-Based Luminophores
No full textThe interaction of europium nitrate with triazine-based luminophores, namely 3-(pyridin-2-yl)triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]triazine (L1), 3-(pyridin-4-yl)triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]triazine (L2), and 3,7,11-tri(pyridin-4-yl)triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]triazine (L3), resulted in three Eu(III) compounds with the compositions (L1H)[Eu(NO3)4(H2O)2] (1), (L2HL2)2[Eu(NO3)5(H2O)] (CH3CN)2 (2), and [Eu(NO3)3(H2O)2(L3)] (3) whose structures were disclosed by single crystal X-ray diffraction analysis. In the organic-inorganic hybrid salts 1 and 2, the direct Eu(III)-triazinic ligand coordination is lacking, while in the neutral complex 3 the direct Eu(III)-L3 coordination occurs through one of the luminophore’s N-pyridine binding sites. The solid-state photoluminescence behavior of 2 and 3 was studied. At room temperature, 2 revealed predominantly the ligand-based photoluminescence in the cyan-blue region of the spectrum when excited at 337 nm; the orange-red Eu(III)-based emission dominated the spectrum when excited at 405 nm. On the other hand, irrespective of the excitation wavelength, compound 3 displayed the characteristic emission of Eu(III), suggesting that the coordinated L3 ligand effectively played an antenna effect toward the metal. The Eu(III)-based contribution in photoluminescence in 2 and 3 displayed an opposite thermochromic behavior when monitored in the 12-300 K range. Specifically, the emission intensity decreases for 2 and increases for 3 with an increase in the temperature. The unusual thermochromic effect for 3 was hypothesized from a density of states (DOS) viewpoint
The Rise and Decline of Catching Up Development. An Experience of Russia and Latin America with Implications for Asian 'Tigers'
No full textThis book deals with the general problems of catching up development, which have been considered through lenses of the concrete cases studies of the former Soviet Union and post-Soviet Russia, Latin American and East Asian countries. The book is subdivided into two parts. In the first part, some general problems of development in the past century are considered and draw attention to the cases of Russia and Latin American countries. The second part is devoted to the NICs of E/SEA.Development, neo-liberal Reforms, globalization, crisis
Crystalline multicomponent compounds involving hexaammine cobalt( iii ) cations
No full textA new series of multicomponent compounds containing the cation [Co(NH3)6]3+ and various organic N-, N,O-, and O-donor moieties has been synthesized and crystallized. The series involves [Co(NH3)6]Cl3·2(phen)·3H2O (1), [Co(NH3)6](Hbdc)(bdc)·3H2O (2), [Co(NH3)6]Cl2(Hpht)·3H2O (3), [Co(NH3)6]Cl(Hpht)2·3H2O (4), [Co(NH3)6]Cl(2,3-pdc)·H2O (5), [Co(NH3)6]11[Co(2,5-pdc)3]8Cl·84H2O (6), [Co(NH3)6][Co(3,5-pdc)2(H2O)4]Cl·3H2O (7), [Co(NH3)6]Cl(sb)·4H2O (8), and [Co(NH3)6]2(sb)3·EtOH·2.5H2O (9) (where phen = 1,10-phenanthroline, H2bdc = diphenyl-4,4′-dicarboxylic acid, H2pht = o-phthalic acid, H2pdc = 2,3-/2,5-/3,5-pyridinedicarboxylic acid, H2sb = 4-sulfobenzoic acid). Single crystal X-ray diffraction studies have revealed that in these compounds the [Co(NH3)6]3+ cation serves as a building block for the incorporation of various anions/molecules and promotes the formation of multicomponent compounds with extended charge-supported networks between cations and anions and others such as H-bonds between charged⋯neutral and neutral⋯neutral components as well as π–π stacking interactions. In addition to the [Co(NH3)6]3+ cations, compounds 1–9 contain in changing composition Cl−, deprotonated phthalate, diphenyldicarboxylate, pyridinedicarboxylate, and sulfonate anions or complex [Co(2,5-pdc)3]4− and [Co(3,5-pdc)2(H2O)4]2− anions, as well as neutral 1,10-phenanthroline and ethanol and water molecules as components of the crystallization. Hirshfeld surface analysis was also performed to discuss the strength of hydrogen bonds and to quantify the inter-contacts. Energy decomposition analysis of the intermolecular interaction energy was performed using the SAPT method to study the non-covalent bonding interactions of [Co(NH3)6]3+ cations with mono-, dianions and neutral molecules, and it was found that the calculated bonding energy for compound 1 is minimal. Compounds 1–9 were tested in vitro against Rhizobium (Agrobacterium) vitis, an oncogenic bacterium that causes tumor formation in plants. Compound 1, comprising hexaammine cobalt(III) chloride and 1,10-phenanthroline, showed the highest inhibitory potential and is thus qualified for an application against bacterial cancer in plants
Template‐Directed Assembly of Zeolite‐like Metal–Organic Frameworks (ZMOFs): A usf‐ZMOF with an Unprecedented Zeolite Topology
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