scholarly journals Extended π-Systems in Diimine Ligands in [Cu(P^P)(N^N)][PF6] Complexes: From 2,2′-Bipyridine to 2-(Pyridin-2-yl)Quinoline

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 255 ◽  
Author(s):  
Sarah Keller ◽  
Murat Alkan-Zambada ◽  
Alessandro Prescimone ◽  
Edwin C. Constable ◽  
Catherine E. Housecroft
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Photophysical Properties ◽  
Coordination Environment ◽  
Face To Face ◽  
Diimine Ligands ◽  
Structural Database ◽  
The Impact ◽  
Packing Effects

We describe the synthesis and characterization of [Cu(POP)(1)][PF6], [Cu(POP)(2)][PF6], [Cu(xantphos)(1)][PF6], and [Cu(xantphos)(2)][PF6] in which ligands 1 and 2 are 2-(pyridin-2-yl)quinoline and 2-(6-methylpyridin-2-yl)quinoline, respectively. With 2,2'-bipyridine (bpy) as a benchmark, we assess the impact of the extended π-system on structural and solid-state photophysical properties. The single crystal structures of [Cu(POP)(2)][PF6], [Cu(xantphos)(1)][PF6], and [Cu(xantphos)(2)][PF6] were determined and confirmed a distorted tetrahedral copper(I) coordination environment in each [Cu(P^P)(N^N)]+ cation. The xanthene unit in [Cu(xantphos)(1)][PF6] and [Cu(xantphos)(2)][PF6] hosts the quinoline unit of 1, and the 6-methylpyridine group of 2. 1H NMR spectroscopic data indicate that these different ligand orientations are also observed in acetone solution. In their crystal structures, the [Cu(POP)(2)]+, [Cu(xantphos)(1)]+, and [Cu(xantphos)(2)]+ cations exhibit different edge-to-face and face-to-face π-interactions, but in all cases, the copper(I) centre is effectively protected by a ligand sheath. In [Cu(POP)(2)][PF6], pairs of cations engage in an efficient face-to-face π-stacking embrace, and we suggest that this may contribute to this compound having the highest photoluminescence quantum yield (PLQY = 21%) of the series. With reference to data from the Cambridge Structural Database, we compare packing effects and PLQY data for the complexes incorporating 2-(pyridin-2-yl)quinoline and 2-(6-methylpyridin-2-yl)quinoline, with those of the benchmark bpy-containing compounds. We also assess the effect that Cu⋯O distances in the {Cu(POP)} and {Cu(xantphos)} domains of [Cu(P^P)(N^N)][X] compounds have on solid-state PLQY values.

scholarly journals Exploring the Characteristics and Influencing Factors of Leisure Walking Based on the Demand of Behavior

2021 ◽  
Vol 13 (8) ◽  
pp. 4105
Author(s):  
Yupei Jiang ◽  
Honghu Sun
Keyword(s):  
Health Benefits ◽  
Health Benefit ◽  
Public Health Research ◽  
Space Time ◽  
Time Behavior ◽  
Walking Behavior ◽  
Face To Face ◽  
Residential Neighborhood ◽  
The Impact

Leisure walking has been an important topic in space-time behavior and public health research. However, prior studies pay little attention to the integration and the characterization of diverse and multilevel demands of leisure walking. This study constructs a theoretical framework of leisure walking behavior demands from three different dimensions and levels of activity participation, space-time opportunity, and health benefit. On this basis, through a face-to-face survey in Nanjing, China (N = 1168, 2017–2018 data), this study quantitatively analyzes the characteristics of leisure walking demands, as well as the impact of the built environment and individual factors on it. The results show that residents have a high demand for participation and health benefits of leisure walking. The residential neighborhood provides more space opportunities for leisure walking, but there is a certain constraint on the choice of walking time. Residential neighborhood with medium or large parks is more likely to satisfy residents’ demands for engaging in leisure walking and obtaining high health benefits, while neighborhood with a high density of walking paths tends to limit the satisfaction of demands for space opportunity and health benefit. For residents aged 36 and above, married, or retired, their diverse demands for leisure walking are more likely to be fulfilled, while those with high education, medium-high individual income, general and above health status, or children (<18 years) are less likely to be fulfilled. These finding that can have important implications for the healthy neighborhood by fully considering diverse and multilevel demands of leisure walking behavior.

scholarly journals Crystal structures of 4-chloropyridine-2-carbonitrile and 6-chloropyridine-2-carbonitrile exhibit different intermolecular π-stacking, C—H...Nnitrileand C—H...Npyridineinteractions

2015 ◽  
Vol 71 (7) ◽  
pp. 852-856 ◽  
Author(s):  
Matthew J. Montgomery ◽  
Thomas J. O'Connor ◽  
Joseph M. Tanski
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Pyridine Ring ◽  
Nitrile Group ◽  
Two Dimensional ◽  
One Dimensional ◽  
Face To Face ◽  
Π Stacking

The two title compounds are isomers of C6H3ClN2containing a pyridine ring, a nitrile group, and a chloro substituent. The molecules of each compound pack together in the solid state with offset face-to-face π-stacking, and intermolecular C—H...Nnitrileand C—H...Npyridineinteractions. 4-Chloropyridine-2-carbonitrile, (I), exhibits pairwise centrosymmetric head-to-head C—H...Nnitrileand C—H...Npyridineinteractions, forming one-dimensional chains, which are π-stacked in an offset face-to-face fashion. The intermolecular packing of the isomeric 6-chloropyridine-2-carbonitrile, (II), which differs only in the position of the chloro substituent on the pyridine ring, exhibits head-to-tail C—H...Nnitrileand C—H...Npyridineinteractions, forming two-dimensional sheets which are π-stacked in an offset face-to-face fashion. In contrast to (I), the offset face-to-face π-stacking in (II) is formed between molecules with alternating orientations of the chloro and nitrile substituents.

scholarly journals Switching the Conformation of 3,2′:6′,3″-tpy Domains in 4′-(4-n-Alkyloxyphenyl)-3,2′:6′,3″-Terpyridines

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3162 ◽  
Author(s):  
Dalila Rocco ◽  
Alessandro Prescimone ◽  
Edwin C. Constable ◽  
Catherine E. Housecroft
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Crystal Structures ◽  
Dominant Role ◽  
Van Der Waals Interactions ◽  
Single Crystal Structures ◽  
Solid State Structures ◽  
Packing Interactions ◽  
Adjacent Sheet

The preparation and characterization of 4′-(4-n-octyloxyphenyl)-3,2′:6′,3″-terpyridine (8) and 4′-(4-n-nonyloxyphenyl)-3,2′:6′,3″-terpyridine (9) are reported. The single crystal structures of 4′-(4-n-hexyloxyphenyl)-3,2′:6′,3″-terpyridine (6), 4′-(4-n-heptyloxyphenyl)-3,2′:6′,3″-terpyridine (7), and compounds 8 and 9 have been determined. The conformation of the 3,2′:6′,3″-tpy unit is trans,trans in 6 and 7, but switches to cis,trans in 8 and 9. This is associated with significant changes in the packing interactions with a more dominant role for van der Waals interactions between adjacent n-alkyloxy chains and C–Hmethylene... π interactions in 8 and 9. The solid-state structures of 6 and 7 with the n-hexyloxy and n-heptyloxy chains feature interwoven sheets of supramolecular assemblies of molecules, with pairs of n-alkyloxy chains threaded through cavities in an adjacent sheet.

Imidazole-containing Bispidine Ligands: Synthesis, Structure and Cu(II) Complexation

2011 ◽  
Vol 66 (7) ◽  
pp. 721-728 ◽  
Author(s):  
Martin Walther ◽  
Madlen Matterna ◽  
Stefanie Juran ◽  
Silke Fähnemann ◽  
Holger Stephan ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Enol Form ◽  
Trans Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Impact ◽  
Configurational Isomerism

The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state.

Tris{(diphenylphosphino)dimethylsilyl}methane: a sterically hindered tripod

1999 ◽  
Vol 77 (11) ◽  
pp. 1931-1940 ◽  
Author(s):  
Dawn M Friesen ◽  
Robert McDonald ◽  
Lisa Rosenberg
Keyword(s):  
Solid State ◽  
Variable Temperature ◽  
State Structure ◽  
Hindered Rotation ◽  
Solid State Structure ◽  
Conformational Preferences ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
The Impact

The synthesis and characterization of a new tripodal tris(phosphine) molecule, HC(Me2SiPPh2)3 (3) is described. The impact of dimethylsilyl "elbows" on the conformational preferences of this tris(dimethylsilyl)methane core in solution and in the solid state was assessed for 3 and its precursor HC(Me2SiBr)3 (2). Hindered rotation around the "arms" of 3, evident from its solid state structure, has been probed in solution by variable temperature, 1H{31P} NMR spectroscopy, and molecular modelling studies based on the solid state structure of 2 also indicate significant barriers to rotation in this molecule. The susceptibility of 3 to cleavage of the P-Si bonds by protic reagents is described.Key words: tripodal tris(phosphine), polyphosphine, trisilylmethane, C3-symmetry.

Mono- and difunctional furan-based 1,2,3,5-dithiadiazolyl radicals; preparation and solid state structures of 2,5-[(S2N2C)OC4H2(CN2S2)] and 2,5-[(S2N2C)OC4H2(CN)]

1992 ◽  
Vol 70 (3) ◽  
pp. 919-925 ◽  
Author(s):  
A. Wallace Cordes ◽  
Charles M. Chamchoumis ◽  
Robin G. Hicks ◽  
Richard T. Oakley ◽  
Kelly M. Young ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
The Mean ◽  
Solid State Structures ◽  
Solid State Characterization

The preparation and solid state characterization of the bifunctional radical furan-2,5-bis(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN2S2)] and the related monofunctional radical 2-cyanofuran-5-(1,2,3,5-dithiadiazolyl) 2,5-[(S2N2C)OC4H2(CN)] are described. The crystal structure of 2,5-[(S2N2C)OC4H2(CN2S2)] is orthorhombic, space group Pna21, and consists of interleaved arrays of dimers, for which the mean interannular [Formula: see text] contact is 3.137 Å. The crystal structure of the monofunctional radical 2,5-[(S2N2C)OC4H2(CN)] is monoclinic, space group P21/n, and consists of a ribbon-like network of dimers (mean interannular [Formula: see text] interconnected by close head-to-tail [Formula: see text] contacts. The dimer units form stacks parallel to z, with a mean interdimer [Formula: see text] separation of 3.956 Å. The similarities and differences between these two crystal structures and those of related benzene-substituted systems are discussed. Keywords: dithiadiazolyl radicals, furan-based diradicals, cyanofuran-based radicals, radical dimers, crystal structures.

scholarly journals Chimera Diimine Ligands in Emissive [Cu(P^P)(N^N)][PF6] Complexes

Inorganics ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 33 ◽  
Author(s):  
Marco Meyer ◽  
Fabian Brunner ◽  
Alessandro Prescimone ◽  
Edwin C. Constable ◽  
Catherine E. Housecroft
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Photophysical Properties ◽  
Phenyl Ether ◽  
Steric Effects ◽  
Single Crystal Structures ◽  
Diimine Ligands ◽  
Chelating Ligand ◽  
Tetrahedral Environment ◽  
Related Compounds

The syntheses and characterizations of the chelating ligand 6-chloro-6′-methyl-2,2′-bipyridine (6-Cl-6′-Mebpy) and of the copper(I) compounds [Cu(POP)(6-Cl-6′-Mebpy)][PF6] and [Cu(xantphos)(6-Cl-6′-Mebpy)][PF6] (POP = bis(2-(diphenylphosphanyl)phenyl)ether and xantphos = 4,5-bis(diphenylphosphanyl)-9,9-dimethyl-9H-xanthene) are described. The single crystal structures of both complexes were determined; the copper(I) ion is in a distorted tetrahedral environment and in [Cu(xantphos)(6-Cl-6′-Mebpy)][PF6], the disorder of the 6-Cl-6′-Mebpy ligand indicates there is no preference of the ‘bowl’-like cavity of the xanthene unit to host either the methyl or chloro-substituent, consistent with comparable steric effects of the two groups. The electrochemical and photophysical properties of [Cu(POP)(6-Cl-6′-Mebpy)][PF6] and [Cu(xantphos)(6-Cl-6′-Mebpy)][PF6] were investigated and are compared with those of the related compounds containing 6,6′-dichloro-2,2′-bipyridine or 6,6′-dimethyl-2,2′-bipyridine ligands. Trends in properties of the [Cu(P^P)(N^N)]+ complexes were consistent with 6-Cl-6′-Mebpy behaving as a combination of the two parent ligands.

scholarly journals Blue fluorescence from N,O-coordinated BF2 complexes having aromatic chromophores in solution and the solid state

2019 ◽  
Vol 18 (12) ◽  
pp. 2884-2892 ◽  
Author(s):  
Minoru Yamaji ◽  
Kazuhiro Tomonari ◽  
Keisuke Ikuma ◽  
Kenta Goto ◽  
Fumito Tani ◽  
...  
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Photophysical Properties ◽  
Blue Fluorescence

N,O-Coordinated BF2 complexes (Ar@HCs) having aromatic (Ar) and heterocycle (HC) moieties were prepared, and their photophysical properties were investigated in solution and the solid state along with their crystal structures.

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