scholarly journals Diversifying the luminescence of phenanthro-diimine ligands in zinc complexes

2021 ◽  
Author(s):  
Diana Temerova ◽  
Kristina S. Kisel ◽  
Toni Eskelinen ◽  
Alexei S. Melnikov ◽  
Niko Kinnunen ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Zinc Complexes ◽  
Diimine Ligands ◽  
Diimine Ligand

Strongly blue fluorescent 1-phenyl-2-(pyridin-2-yl)-1H-phenanthro[9,10-d]imidazole (L1) is a facile block for the construction of multichromophore organic molecules, and simultaneously serves as a chelating diimine ligand.

scholarly journals Imidazo-Phenanthroline Ligands as a Convenient Modular Platform for the Preparation of Heteroleptic Cu(I) Photosensitizers

Inorganics ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 134 ◽  
Author(s):  
Marie-Ann Schmid ◽  
Martin Rentschler ◽  
Wolfgang Frey ◽  
Stefanie Tschierlei ◽  
Michael Karnahl
Keyword(s):  
Essential Feature ◽  
Photophysical Properties ◽  
Diimine Ligands ◽  
Starting Point ◽  
Diimine Ligand ◽  
Modular Platform ◽  
20 Nm ◽  
And Storage ◽  
Current Energy ◽  
Bright Emission

The capture and storage of solar energy is a promising option to overcome current energy issues. To put such systems into practice, molecular photosensitizers should be based on abundant metals and possess a strong absorption capability for visible light. Therefore, a systematic series of four novel heteroleptic Cu(I) complexes of the type [(P^P)Cu(N^N)]+ (with P^P = xantphos and N^N = different diimine ligands) has been prepared. As an essential feature, these copper photosensitizers contain an imidazole moiety at the backbone of the diimine ligand, which increases the aromatic π-system compared to phenanthroline type ligands. Moreover, 2-(4-bromophenyl)-1-phenyl-1H-imidazo-[4,5-f][1,10]phenanthroline was used as a starting point and modular platform for gradually extended diimine ligands. Suzuki cross-coupling was applied to introduce different kind of substituents in the back of this ligand. Afterwards, a combination of NMR spectroscopy, mass spectrometry, X-ray analysis, cyclic voltammetry, UV/vis and emission spectroscopy was used to investigate the structural, electrochemical and photophysical properties of these compounds. As a result, a reversible reduction, strongly increased extinction coefficients and significantly redshifted absorption maxima (>20 nm) were found compared to traditional Cu(I) photosensitizers without an imidazo moiety. Moreover, these compounds show a bright emission in the solid state.

Synthesis and structures of mononuclear and dinuclear gallium complexes with α-diimine ligands: reduction of the metal or ligand?

2016 ◽  
Vol 45 (1) ◽  
pp. 246-252 ◽  
Author(s):  
Yanxia Zhao ◽  
Yanyan Liu ◽  
Qian-Shu Li ◽  
Ji-Hu Su
Keyword(s):  
Oxidation State ◽  
Oxidation States ◽  
Lower Oxidation State ◽  
Diimine Ligands ◽  
Diimine Ligand ◽  
Dianionic Ligands ◽  
Lower Oxidation ◽  
Gallium Complexes

A series of gallium complexes with different oxidation states of ligand and metal were obtained, both monoanionic and dianionic ligands can be further reduced, where reduction of the radical monoanionic α-diimine ligand into dianion or of Ga (+3) into the lower oxidation state Ga (+2) or Ga (+1.5) takes place.

Binuclear Zinc Complexes with Radical-Anionic Diimine Ligands

2009 ◽  
Vol 28 (13) ◽  
pp. 3863-3868 ◽  
Author(s):  
Igor L. Fedushkin ◽  
Olga V. Eremenko ◽  
Alexandra A. Skatova ◽  
Alexander V. Piskunov ◽  
Georgi K. Fukin ◽  
...  
Keyword(s):  
Zinc Complexes ◽  
Diimine Ligands

Transition metal complexes of a sterically demanding diimine ligand

2005 ◽  
Vol 83 (5) ◽  
pp. 477-484 ◽  
Author(s):  
Jason D Masuda ◽  
Douglas W Stephan
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Key Words ◽  
Transition Metal Complexes ◽  
Metal Halide ◽  
Chelate Complexes ◽  
X Ray ◽  
Diimine Ligands ◽  
Sterically Demanding ◽  
Diimine Ligand

The reaction of the metal halide with the sterically demanding ligand (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2 afforded the complexes (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2MX2 (X = Cl, M = Fe (2), Co (3); X = Br, M = Ni (4), M = Cu (5), Zn (6)). The species of 2 reacts with Li(OEt2)B(C6F5)4 to form the yellow adduct [(i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2Fe(µ-Cl)2Li(OEt2)2][B(C6F5)4] (7) while alkylation of 2 gave (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2FeClCH2SiMe3 (8). The species [(i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2Ni(η3-C3H5)][B(3,5-CF3C6H3)4] (9) was obtained from reaction of 1 with [(η3-C3H5)NiBr]2 and [Na][B(3,5-(CF3)2C6H3)4] while reaction of 4 with Super-Hydride afforded (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2NiH2BEt2 (10). X-ray data are reported for 2–10. The sterically demanding nature of the ligand inhibits subsequent reactivity of these species. Key words: sterically demanding ligands, chelate complexes, X-ray structure, diimine ligands.

scholarly journals Synthesis and crystal structures of manganese(I) carbonyl complexes bearing ester-substituted α-diimine ligands

2020 ◽  
Vol 76 (9) ◽  
pp. 1433-1436
Author(s):  
Takatoshi Kanno ◽  
Tsugiko Takase ◽  
Dai Oyama
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Coordination Sphere ◽  
Carbonyl Complexes ◽  
Complex Molecules ◽  
Carbonyl Ligands ◽  
Distorted Octahedral Coordination ◽  
Diimine Ligands ◽  
Distorted Octahedral ◽  
Diimine Ligand

The crystal structures of two manganese(I) complexes with ester-substituted bipyridine or biquinoline supporting ligands are reported, namely, fac-bromidotricarbonyl(diethyl 2,2′-bipyridine-4,4′-dicarboxylate-κ2 N,N′)manganese(I), [MnBr(C16H16N2O4)(CO)3], I, and fac-bromidotricarbonyl(diethyl 2,2′-biquinoline-4,4′-dicarboxylate-κ2 N,N′)manganese(I), [MnBr(C24H20N2O4)(CO)3], II. In both complexes, the manganese(I) atom adopts a distorted octahedral coordination sphere defined by three carbonyl C atoms, a Br− anion and two N atoms from the chelating α-diimine ligand. Both complexes show fac configurations of the carbonyl ligands. In I, the complex molecules are linked by C—H...Br hydrogen bonds and aromatic π–π contacts. In II, intramolecular C—H...O hydrogen bonds are present as well as intermolecular C—H...O and C—H...Br hydrogen bonds and π–π interactions.

Multistep Electrochemical Reduction Path of Clusters [Os3(CO)10(α-diimine)]: Comparison of Electrochemical and Photochemical Os-Os(α-diimine) Bond Cleavage

2006 ◽  
Vol 71 (2) ◽  
pp. 237-263 ◽  
Author(s):  
František Hartl ◽  
Josephina W. M. van Outersterp
Keyword(s):  
Electrochemical Reduction ◽  
Radical Anion ◽  
Bond Cleavage ◽  
Polymeric Chain ◽  
Parent Cluster ◽  
Diimine Ligands ◽  
Diimine Ligand ◽  
Electron Reduction ◽  
Open Core ◽  
Reactive Cluster

Electrochemical reduction of the triangular clusters [Os3(CO)10(α-diimine)] (α-diimine = 2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpym)) and [Os3(CO)10(μ-bpym)ReBr(CO)3] produces primarily the corresponding radical anions. Their stability is strongly determined by the π-acceptor ability of the reducible α-diimine ligand, which decreases in the order μ-bpym > bpym >> bpy. Along this series, increasing delocalisation of the odd electron density in the radical anion over the Os(α-diimine) chelate ring causes weakening of the axial (CO)4Os-Os(CO)2(α-diimine) bond and its facile cleavage for α-diimine = bpy. In contrast, the cluster radical anion is inherently stable for the bridging bpym ligand, the strongest π-acceptor in the studied series. In the absence of the partial delocalisation of the unpaired electron over the Re(bpym) chelate bond, the Os3-core of the radical anion remains intact only at low temperatures. Subsequent one-electron reduction of [Os3(CO)10(bpym)]•- at T = 223 K gives the open-triosmium core (= Os3*) dianion, [Os3*(CO)10(bpym)]2-. Its oxidation leads to the recovery of parent [Os3(CO)10(bpym)]. At room temperature, [Os3*(CO)10(bpym)]2- is formed along a two-electron (ECE) reduction path. The chemical step (C) results in the formation of an open-core radical anion that is directly reducible at the cathodic potential of the parent cluster in the second electrochemical (E) step. In weakly coordinating tetrahydrofuran, [Os3*(CO)10(bpym)]2- rapidly attacks yet non-reduced parent cluster molecules, producing the relatively stable open-core dimer [Os3*(CO)10(bpym)]22- featuring two open-triangle cluster moieties connected with an (bpym)Os-Os(bpym) bond. In butyronitrile, [Os3*(CO)10(bpym)]2- is stabilised by the solvent and the dimer [Os3*(CO)10(bpym)]22- is then mainly formed by reoxidation of the dianion on reverse potential scan. The more reactive cluster [Os3(CO)10(bpy)] follows the same reduction path, as supported by spectroelectrochemical results and additional valuable evidence obtained from cyclic voltammetric scans. The ultimate process in the reduction mechanism is fragmentation of the cluster core triggered by the reduction of the dimer [Os3*(CO)10(α-diimine)]22-. The products formed are [Os2(CO)8]2- and {Os(CO)2(α-diimine)}2. The latter dinuclear fragments constitute a linear polymeric chain [Os(CO)2(α-diimine)]n that is further reducible at the α-diimine ligands. For α-diimine = bpy, the charged polymer is capable of reducing carbon dioxide. The electrochemical opening of the triosmium core in the [Os3(CO)10(α-diimine)] clusters exhibits several common features with their photochemistry. The same Os-α-diimine bond dissociates in both cases but the intimate mechanisms are different.

Electrochemical Oxidation of W(CO)4(LL): Generation, Characterization, and Reactivity of [W(CO)4(LL)]+ (LL=α-diimine ligands)

2017 ◽  
Vol 70 (9) ◽  
pp. 1006 ◽  
Author(s):  
John P. Bullock ◽  
Chong-Yong Lee ◽  
Brian Hagan ◽  
Humair Madhani ◽  
John Ulrich
Keyword(s):  
Kinetic Studies ◽  
Radical Cations ◽  
Reaction Scheme ◽  
Diimine Ligands ◽  
Steric Crowding ◽  
Diimine Ligand ◽  
Major Reaction ◽  
Weakly Coordinating ◽  
The One

The electrochemistry of a series of W(CO)4(LL) complexes, where LL is an aromatic α-diimine ligand, was examined in coordinating and weakly coordinating media using several techniques. These compounds undergo metal-centred one-electron oxidations and the electrogenerated radical cations undergo a range of subsequent chemical steps, the nature of which depends on the substituents of the α-diimine ligand and the presence of coordinating species. In CH2Cl2/TBAPF6, where TBAPF6 is n-tetrabutylammonium hexaflurophosphate, the bulk oxidations are partially reversible at scan rates of 0.25 V s−1; the resulting tungsten(i) radicals react via disproportionation and loss of carbonyl, the rate constants for which were measured by double-potential step chronocoulometry. Large-amplitude a.c. voltammetry experiments suggest that the one-electron oxidized species are in equilibrium with the corresponding disproportionation products. Steric crowding of the metal centre prolongs the lifetime of the radical cations, allowing the infrared spectroelectrochemical characterization of two [W(CO)4(LL)]+ species. Electrogenerated [W(CO)4(LL)]+ cations are highly susceptible to attack by potential ligands; oxidations performed in CH3CN/TBAPF6, for example, were chemically irreversible. Kinetic studies in weakly coordinating media show that near-stoichiometric amounts of added pyridine and acetonitrile are enough to greatly diminish the reversibility of the bulk oxidations; the dominant path of the coupled chemistry depends on the ligand strength, with substitution being the major reaction with added pyridine, whereas disproportionation is favoured by the presence of acetonitrile. A reaction scheme that provides an overall framework of the reactions followed by the radical cations is presented and discussed in the context of the previously observed chemistry of the molybdenum analogues.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

Direct phase determination in electron crystallography: small organic molecules

1992 ◽  
Vol 50 (2) ◽  
pp. 1166-1167
Author(s):  
Douglas L. Dorset
Keyword(s):  
Organic Molecules ◽  
Data Sets ◽  
Temperature Structure ◽  
3D Analysis ◽  
Intensity Data ◽  
Electron Crystallography ◽  
Phase Determination ◽  
Measured Intensity ◽  
3D Data

The quantitative use of electron diffraction intensity data for the determination of crystal structures represents the pioneering achievement in the electron crystallography of organic molecules, an effort largely begun by B. K. Vainshtein and his co-workers. However, despite numerous representative structure analyses yielding results consistent with X-ray determination, this entire effort was viewed with considerable mistrust by many crystallographers. This was no doubt due to the rather high crystallographic R-factors reported for some structures and, more importantly, the failure to convince many skeptics that the measured intensity data were adequate for ab initio structure determinations.We have recently demonstrated the utility of these data sets for structure analyses by direct phase determination based on the probabilistic estimate of three- and four-phase structure invariant sums. Examples include the structure of diketopiperazine using Vainshtein's 3D data, a similar 3D analysis of the room temperature structure of thiourea, and a zonal determination of the urea structure, the latter also based on data collected by the Moscow group.

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