Characterization of Benzo[a]naphtho[2,3‐f]pentalene: Interrelation between Open‐shell and Antiaromatic Characters Governed by Mode of the Quinoidal Subunit and Molecular Symmetry

2021 ◽  
Author(s):  
Akihito Konishi ◽  
Koki Horii ◽  
Haruna Iwasa ◽  
Yui Okada ◽  
Ryohei Kishi ◽  
...  
Keyword(s):  
Open Shell ◽  
Molecular Symmetry

scholarly journals Stacking Control by Molecular Symmetry of Sterically Protected Phthalocyanines

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5552
Author(s):  
Ryota Kudo ◽  
Masahiro Sonobe ◽  
Yoshiaki Chino ◽  
Yu Kitazawa ◽  
Mutsumi Kimura
Keyword(s):  
Lamellar Structure ◽  
Synthesis And Characterization ◽  
Molecular Symmetry ◽  
X Ray Diffraction ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Structural Isomers ◽  
X Ray ◽  
Temperature Controlled

The synthesis and characterization of two phthalocyanine (Pc) structural isomers, 1 and 2, in which four 2,6-di(hexyloxy)phenyl units were attached directly to the 1,8,15,22- or 1,4,15,18-positions of the Pc rings, are described. Both Pcs 1 and 2 exhibited low melting points, i.e., 120 and 130 °C respectively, due to the reduction in intermolecular π-π interaction among the Pc rings caused by the steric hindrance of 2,6-dihexyloxybenzene units. The thermal behaviors were investigated with temperature-controlled polarizing optical microscopy, differential scanning calorimetry, powder X-ray diffraction, and absorption spectral analyses. Pc 1, having C4h molecular symmetry, organized into a lamellar structure containing lateral assemblies of Pc rings. In contrast, the other Pc 2 revealed the formation of metastable crystalline phases, including disordered stacks of Pcs due to rapid cooling from a melted liquid.

scholarly journals Substituent Effects of Amines on Genipin Dye Formation – Insights into Dye Origins

2021 ◽  
Author(s):  
Fiona Jeeva ◽  
Chris Caputo
Keyword(s):  
Oxidative Polymerization ◽  
Substituent Effects ◽  
Gel Permeation Chromatography ◽  
Open Shell ◽  
Aliphatic Amines ◽  
Polymerization Reaction ◽  
Unique Reaction ◽  
Dye Absorption ◽  
Interesting Class

<p>Genipin, a naturally occurring iridoid, represents an interesting class of reactive dyes. This colorless molecule produces brilliant blue dyes in the presence of primary aliphatic amines. The mechanism behind this unique reaction has been suggested to proceed via an oxidative polymerization reaction, albeit few studies have investigated this process. By utilizing aromatic amines, we demonstrate that the dye absorption properties can be redshifted to form green dyes as opposed to the blue that is most associated with aliphatic amines. Characterization of the green material with gel-permeation chromatography, mass spectrometry, and electrochemical experiments suggest an alternate structure of the dye molecules and led us to revisit the mechanism behind this reaction. Generation of dyes from the reaction of genipin and methylamine or various aniline derivatives revealed the complete absence of polymeric material and instead revealed a material that contains an open-shell configuration as determined by EPR spectroscopy. Herein we report the first findings that dyes formed from the reaction of genipin with amines form persistent radicals that are likely responsible for their vibrant colors, as opposed to the previously suggested polymer formation. </p>

scholarly journals Substituent Effects of Amines on Genipin Dye Formation – Insights into Dye Origins

2021 ◽  
Author(s):  
Fiona Jeeva ◽  
Chris Caputo
Keyword(s):  
Oxidative Polymerization ◽  
Substituent Effects ◽  
Gel Permeation Chromatography ◽  
Open Shell ◽  
Aliphatic Amines ◽  
Polymerization Reaction ◽  
Unique Reaction ◽  
Dye Absorption ◽  
Interesting Class

<p>Genipin, a naturally occurring iridoid, represents an interesting class of reactive dyes. This colorless molecule produces brilliant blue dyes in the presence of primary aliphatic amines. The mechanism behind this unique reaction has been suggested to proceed via an oxidative polymerization reaction, albeit few studies have investigated this process. By utilizing aromatic amines, we demonstrate that the dye absorption properties can be redshifted to form green dyes as opposed to the blue that is most associated with aliphatic amines. Characterization of the green material with gel-permeation chromatography, mass spectrometry, and electrochemical experiments suggest an alternate structure of the dye molecules and led us to revisit the mechanism behind this reaction. Generation of dyes from the reaction of genipin and methylamine or various aniline derivatives revealed the complete absence of polymeric material and instead revealed a material that contains an open-shell configuration as determined by EPR spectroscopy. Herein we report the first findings that dyes formed from the reaction of genipin with amines form persistent radicals that are likely responsible for their vibrant colors, as opposed to the previously suggested polymer formation. </p>

Synthesis of the Open-Shell 3d-Transition Metal(II) Bis(phosphinidenide) [Mn{P(sIDipp)}2]

2022 ◽  
Author(s):  
Ruth Weller ◽  
Markus Balmer ◽  
Carsten von Hänisch ◽  
Gunnar Werncke
Keyword(s):  
Transition Metal ◽  
Open Shell ◽  
Synthesis And Characterization

The synthesis and characterization of the first homoleptic open-shell transition metal phosphinidenide is presented. By reacting [MnL2] (L = −N(SiMe3)2) with [(sIDipp)PK] (sIDipp = 1,3-bis(2,6-di-iso-propylphenyl)-imidazolidine-2-ylidene), the formation of [Mn{P(sIDipp)}2] instead...

Spectroscopic Characterization of Open-Shell Cations: Emission and Laser Excitation spectra of Rotationally Cooled CH3(C?C)2X+, X = Cl, Br

1984 ◽  
Vol 67 (5) ◽  
pp. 1222-1232 ◽  
Author(s):  
Dieter Klapstein ◽  
Robert Kuhn ◽  
John P. Maier ◽  
Liubomir Misev ◽  
Martin Ochsner
Keyword(s):  
Laser Excitation ◽  
Spectroscopic Characterization ◽  
Open Shell ◽  
Excitation Spectra

scholarly journals Experimental and theoretical characterization of the Zn—Zn bond in [Zn2(η5-C5Me5)2]

2007 ◽  
Vol 63 (6) ◽  
pp. 862-868 ◽  
Author(s):  
Juan F. Van der Maelen ◽  
Enrique Gutiérrez-Puebla ◽  
Ángeles Monge ◽  
Santiago García-Granda ◽  
Irene Resa ◽  
...  
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Topological Analysis ◽  
Open Shell ◽  
Synchrotron Diffraction ◽  
Functional Theory ◽  
Metal Metal ◽  
Moller Plesset ◽  
Experimental Electron Density

The existence and characterization of a bond between the Zn atoms in the recently synthesized complex [Zn2(η5-C5Me5)2], as well as between Zn and ligand C atoms is firmly based on neutron diffraction and low-temperature X-ray synchrotron diffraction experiments. The multipolar analysis of the experimental electron density and its topological analysis by means of the `Atoms in Molecules' (AIM) approach reveals details of the Zn—Zn bond, such as its open-shell intermediate character (the results are consistent with a typical metal–metal single bond), as well as many other topological properties of the compound. Experimental results are also compared with theoretical ab initio calculations of the DFT (density functional theory) and MP2 (Møller-Plesset perturbation theory) electron densities, giving a coherent view of the bonding in the complex. For instance, charges calculated from the AIM approach applied to the atomic basin of each Zn atom are, on average, +0.72 e from both the experimental and the theoretical electron density, showing a moderate charge transfer from the metal, confirmed by the calculated topological indexes.

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