ChemInform Abstract: A Novel Bis(N,N′-dimethyl-1,4,7-triazacyclononane)calix(4)arene Ligand That Forms a Ferromagnetic Dinuclear Nickel(II) Complex with Three End- on Azide Bridging Ligands

ChemInform ◽  
2010 ◽  
Vol 26 (37) ◽  
pp. no-no
Author(s):  
P. D. BEER ◽  
M. G. B. DREW ◽  
P. B. LEESON ◽  
K. LYSSENKO ◽  
M. I. OGDEN
Keyword(s):  
Bridging Ligands ◽  
Arene Ligand

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding

2019 ◽  
Author(s):  
Andrew Rosen ◽  
M. Rasel Mian ◽  
Timur Islamoglu ◽  
Haoyuan Chen ◽  
Omar Farha ◽  
...  
Keyword(s):  
Density Functional ◽  
Metal Organic Frameworks ◽  
Redox Activity ◽  
Screening Methods ◽  
Bridging Ligands ◽  
Metal Centers ◽  
Computational Screening ◽  
Open Metal Sites ◽  
Metal Organic ◽  
Unsaturated Metal Sites

<p>Metal−organic frameworks (MOFs) with coordinatively unsaturated metal sites are appealing as adsorbent materials due to their tunable functionality and ability to selectively bind small molecules. Through the use of computational screening methods based on periodic density functional theory, we investigate O<sub>2</sub> and N<sub>2</sub> adsorption at the coordinatively unsaturated metal sites of several MOF families. A variety of design handles are identified that can be used to modify the redox activity of the metal centers, including changing the functionalization of the linkers (replacing oxido donors with sulfido donors), anion exchange of bridging ligands (considering μ-Br<sup>-</sup>, μ-Cl<sup>-</sup>, μ-F<sup>-</sup>, μ-SH<sup>-</sup>, or μ-OH<sup>-</sup> groups), and altering the formal oxidation state of the metal. As a result, we show that it is possible to tune the O<sub>2</sub> affinity at the open metal sites of MOFs for applications involving the strong and/or selective binding of O<sub>2</sub>. In contrast with O<sub>2</sub> adsorption, N<sub>2</sub> adsorption at open metal sites is predicted to be relatively weak across the MOF dataset, with the exception of MOFs containing synthetically elusive V<sup>2+</sup> open metal sites. As one example from the screening study, we predict that exchanging the μ-Cl<sup>-</sup> ligands of M<sub>2</sub>Cl<sub>2</sub>(BBTA) (H<sub>2</sub>BBTA = 1<i>H</i>,5<i>H</i>-benzo(1,2-d:4,5-d′)bistriazole) with μ-OH<sup>-</sup> groups would significantly enhance the strength of O<sub>2</sub> adsorption at the open metal sites without a corresponding increase in the N<sub>2</sub> affinity. Experimental investigation of Co<sub>2</sub>Cl<sub>2</sub>(BBTA) and Co<sub>2</sub>(OH)<sub>2</sub>(BBTA) confirms that the former exhibits only weak physisorption, whereas the latter is capable of chemisorbing O<sub>2</sub> at room temperature. The chemisorption behavior is attributed to the greater electron-donating character of the μ-OH<sup>-</sup><sub> </sub>ligands and the presence of H-bonding interactions between the μ-OH<sup>-</sup> bridging ligands and the O<sub>2</sub> adsorbate.</p>

Exchange-Biasing in a Dinuclear Dysprosium(III) Single-Molecule Magnet with a Large Energy Barrier for Magnetization Reversal

2019 ◽  
Author(s):  
Tian Han ◽  
Marcus J. Giansiracusa ◽  
Zi-Han Li ◽  
You-Song Ding ◽  
Nicholas F. Chilton ◽  
...  
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Energy Barrier ◽  
Magnetic Hysteresis ◽  
Large Energy ◽  
Magnetic Studies ◽  
Bridging Ligands ◽  
Single Molecule Magnet ◽  
Exchange Biasing

A dichlorido-bridged dinuclear dysprosium(III) single-molecule magnet [Dy<sub>2</sub>L<sub>2</sub>(<i>µ</i>-Cl)<sub>2</sub>(THF)<sub>2</sub>] has been made using a diamine-bis(phenolate) ligand, H<sub>2</sub>L. Magnetic studies show an energy barrier for magnetization reversal (<i>U</i><sub>eff</sub>) around 1000 K. Exchange-biasing effect is clearly seen in magnetic hysteresis with steps up to 4 K. <i>Ab</i> initio calculations exclude the possibility of pure dipolar origin of this effect leading to the conclusion that super-exchange <i>via</i> the chloride bridging ligands is important.

Molecular structures and magnetic properties of .mu.-phenolato binuclear copper(II) complexes incorporating chloro, hydroxo, and azido exogenous bridging ligands

1988 ◽  
Vol 27 (21) ◽  
pp. 3710-3716 ◽  
Author(s):  
Azdine Benzekri ◽  
Patrick Dubourdeaux ◽  
Jean Marc Latour ◽  
Jean Laugier ◽  
Paul Rey
Keyword(s):  
Magnetic Properties ◽  
Molecular Structures ◽  
Binuclear Copper ◽  
Bridging Ligands

Mechanistische Untersuchungen zum reversiblen Gleichgewicht von metallorganischen Tripeldecker- und Sandwichkomplexen des Typs [Bis{(η5-CpR)Co}-μ-{η4:η4-aren}] und [(η5-CpR)Co(η6-aren)] / Mechanistic Studies towards the Reversible Equilibrium between Metal Organic Triple Decker and Sandwich Complexes [Bis{(η5 -CpR)Co}-μ-{η4 :η4-arene}] and [{(η5-CpR)Co(η6-arene)]

1998 ◽  
Vol 53 (11) ◽  
pp. 1267-1272 ◽  
Author(s):  
Jörg J. Schneider ◽  
Dirk Wolf
Keyword(s):  
Ligand Exchange ◽  
Sandwich Complexes ◽  
Valuable Metal ◽  
H Nmr ◽  
Synthetic Utility ◽  
Metal Organic ◽  
Arene Ligand ◽  
Benzene Toluene

The arene ligand exchange mechanism of slipped arene triple deckers [Bis{(η5-CpR)Co}-μ-{η4:η4-arene}] (R = Me5, 1,2,4 tri-tert butyl, arene = benzene, toluene) 1 was studied by 1H-NMR spectroscopy for different concentrations and solvents. It has been found that triple deckers of type 1 decompose slowly in solution. A unique equilibrium, between these triple deckers and the mixed sandwich complexes [(η6-arene)Co(η5-CpR)] and 14 e [(η5-Cp)Co]solv fragments generated in situ by decomposition o f 1 exists. In addition to this equilibrium arene lability of the thus formed mixed sandwich complex type has been detected by NMR making slipped triple deckers 1 ideal single source compounds for the generation of two [(η5-Cp)Co] fragments in one reaction step. Such fragments are valuable metal ligand components with high synthetic utility in organometallic chemistry.

scholarly journals 3D Metal–Organic Frameworks Based on Co(II) and Bithiophendicarboxylate: Synthesis, Crystal Structures, Gas Adsorption, and Magnetic Properties

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1269
Author(s):  
Vadim A. Dubskikh ◽  
Anna A. Lysova ◽  
Denis G. Samsonenko ◽  
Alexander N. Lavrov ◽  
Konstantin A. Kovalenko ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gas Adsorption ◽  
Magnetic Moments ◽  
Bet Surface Area ◽  
Separation Performance ◽  
Bridging Ligands ◽  
Magnetization Data ◽  
Metal Organic ◽  
Ch4 Adsorption ◽  
Gas Separation Performance

Three new 3D metal-organic porous frameworks based on Co(II) and 2,2′-bithiophen-5,5′-dicarboxylate (btdc2−) [Co3(btdc)3(bpy)2]·4DMF, 1; [Co3(btdc)3(pz)(dmf)2]·4DMF·1.5H2O, 2; [Co3(btdc)3(dmf)4]∙2DMF∙2H2O, 3 (bpy = 2,2′-bipyridyl, pz = pyrazine, dmf = N,N-dimethylformamide) were synthesized and structurally characterized. All compounds share the same trinuclear carboxylate building units {Co3(RCOO)6}, connected either by btdc2– ligands (1, 3) or by both btdc2– and pz bridging ligands (2). The permanent porosity of 1 was confirmed by N2, O2, CO, CO2, CH4 adsorption measurements at various temperatures (77 K, 273 K, 298 K), resulted in BET surface area 667 m2⋅g−1 and promising gas separation performance with selectivity factors up to 35.7 for CO2/N2, 45.4 for CO2/O2, 20.8 for CO2/CO, and 4.8 for CO2/CH4. The molar magnetic susceptibilities χp(T) were measured for 1 and 2 in the temperature range 1.77–330 K at magnetic fields up to 10 kOe. The room-temperature values of the effective magnetic moments for compounds 1 and 2 are μeff (300 K) ≈ 4.93 μB. The obtained results confirm the mainly paramagnetic nature of both compounds with some antiferromagnetic interactions at low-temperatures T < 20 K in 2 between the Co(II) cations separated by short pz linkers. Similar conclusions were also derived from the field-depending magnetization data of 1 and 2.

scholarly journals Synthesis and Structural Characterization of (E)-4-[(2-Hydroxy-3-methoxybenzylidene)amino]butanoic Acid and Its Novel Cu(II) Complex

Molbank ◽  
10.3390/m1179 ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. M1179
Author(s):  
Eleftherios Halevas ◽  
Antonios Hatzidimitriou ◽  
Barbara Mavroidi ◽  
Marina Sagnou ◽  
Maria Pelecanou ◽  
...  
Keyword(s):  
Schiff Base ◽  
Gamma Aminobutyric Acid ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Polymeric Compound ◽  
Bridging Ligands ◽  
1H And 13C Nmr ◽  
One Dimensional ◽  
Ft Ir

A novel Cu(II) complex based on the Schiff base obtained by the condensation of ortho-vanillin with gamma-aminobutyric acid was synthesized. The compounds are physico-chemically characterized by elemental analysis, HR-ESI-MS, FT-IR, and UV-Vis. The complex and the Schiff base ligand are further structurally identified by single crystal X-ray diffraction and 1H and 13C-NMR, respectively. The results suggest that the Schiff base are synthesized in excellent yield under mild reaction conditions in the presence of glacial acetic acid and the crystal structure of its Cu(II) complex reflects an one-dimensional polymeric compound. The molecular structure of the complex consists of a Cu(II) ion bound to two singly deprotonated Schiff base bridging ligands that form a CuN2O4 chelation environment, and a coordination sphere with a disordered octahedral geometry.

Syntheses, crystal structures, and biological evaluations of new dinuclear platinum(II) complexes with 1,2,4-triazole derivate as bridging ligands

2021 ◽  
Author(s):  
Jianwei Wang ◽  
Xinhua Li ◽  
Caixia Yuan ◽  
Feng Su ◽  
Yanbo Wu ◽  
...  
Keyword(s):  
Crystal Structures ◽  
General Formula ◽  
Bridging Ligands ◽  
Dinuclear Platinum

A series of new dinuclear platinum(II) complexes with general formula [Pt2(μ-HL)4] (1–4), where H2L is 4-[(5-chloro-2-hydroxy-benzylidene)-amino)]-3-R-1,2,4-triazole-5-thione: R = H (1), methyl (2), ethyl (3) and propyl (4), have been synthesized...

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