scholarly journals Unsymmetrical Hexafluorocyclopentene-Linked Twisted π-Conjugated Molecules as Dual-State Emissive Luminophores

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1885
Author(s):  
Shigeyuki Yamada ◽  
Akito Nishizawa ◽  
Kazuki Kobayashi ◽  
Keigo Yoshida ◽  
Masato Morita ◽  
...  
Keyword(s):  
Molecular Design ◽  
Theoretical Calculations ◽  
High Energy ◽  
Single Step ◽  
Molecular Structures ◽  
Structural Shape ◽  
Conjugated Molecules ◽  
Solid States ◽  
The Difference ◽  
Light Green

Dual-state emissive (DSE) luminophores, which can luminesce both in solution and in solid states, have recently attracted significant attention because of their broad applications. However, their development is difficult due to the difference in molecular design between solution- and solid-state luminophores. In this study, DSE luminophores based on unsymmetrical hexafluorocyclopentene-linked twisted π-conjugated structures carrying various substituents to tune the electron-density were designed and synthesized in a single-step reaction from heptafluorocyclopentene or perfluoro-1,2-diphenylcyclopentene derivatives. The twisted π-conjugated luminophores exhibited absorption in the UV region at approximately 330 nm, along with several signals in the high-energy region. Upon irradiating the luminophore solution (wavelength 330 nm), light-green to yellow photoluminescence (PL) was observed in the range of 422–471 nm with high PL efficiency. Theoretical calculations revealed that excitation from ground to excited states altered the structural shape of the luminophores from twisted to planar, leading to red-shifted PL and high PL efficiency (ΦPL). The intense blue PL exhibited by the luminophores in the crystalline state was attributed to their twisted molecular structures that suppressed non-radiative deactivation via the effective blocking of π/π stacking interactions.

Research on Some Novel Trigonal Schiff Base Compounds With Aromatic Core and Different Substituted Groups

2011 ◽  
Vol 197-198 ◽  
pp. 598-601 ◽  
Author(s):  
Ti Feng Jiao ◽  
Juan Zhou ◽  
Jing Xin Zhou ◽  
Qiong Wang ◽  
Xu Zhong Luo
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Schiff Base ◽  
Molecular Design ◽  
Molecular Structures ◽  
Functional Material ◽  
Temperature Ranges ◽  
The Difference ◽  
Structural Influence ◽  
Base Group

Some novel trigonal Schiff base compounds with aromatic core and different substituted groups have been designed and synthesized from the reaction of trigonal aromatic amine with different aldehydes. It has been found that depending on the molecular structures and substituted groups, the formed trigonal Schiff base compounds showed different properties, indicating distinct regulation of molecular design. UV and IR data confirmed commonly the formation of Schiff base as well as aromatic segment in molecular structures. Thermal analysis also clarified the structural influence of these compounds in different temperature ranges. The difference of thermal stability is mainly attributed to molecular structures, formation of Schiff base group and different substituted groups. The present results have showed that the special properties of Schiff base compounds could be turned by modifying molecular structures and substituted groups, which show potential application in fields of functional material and catalyst.

Design and Investigation of Novel L-Glutamate-Based Schiff Base Compounds with Different Substituted Groups

2011 ◽  
Vol 474-476 ◽  
pp. 1529-1533
Author(s):  
Ti Feng Jiao ◽  
Jian Liu ◽  
Jing Xin Zhou ◽  
Xu Hui Li ◽  
Yuan Yuan Xing
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Schiff Base ◽  
Molecular Design ◽  
Molecular Structures ◽  
Functional Material ◽  
Temperature Ranges ◽  
The Difference ◽  
Structural Influence ◽  
Base Group

Some novel L-glutamate-based Schiff base compounds with glutamate segment and different substituted groups have been designed and synthesized from the reaction of aromatic L-glutamate amine with different aldehydes. It has been found that depending on the molecular structures and substituted groups, the formed Schiff base compounds showed different properties, indicating distinct regulation of molecular design. UV and IR data confirmed commonly the formation of Schiff base as well as aromatic substituted groups in molecular structures. Thermal analysis also clarified the structural influence of these compounds in different temperature ranges. The difference of thermal stability is mainly attributed to molecular structures, formation of Schiff base group and different substituted groups. These results indicated that the the special properties of Schiff base compounds could be regulated through the design of molecular structures and substituted groups, which leads to potential application in fields of functional material as well as catalyst.

scholarly journals Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanming Cai ◽  
Jiaju Fu ◽  
Yang Zhou ◽  
Yu-Chung Chang ◽  
Qianhao Min ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Active Sites ◽  
Theoretical Calculations ◽  
High Energy ◽  
Single Atom ◽  
Faradaic Efficiency ◽  
High Energy Barrier ◽  
Catalytic Sites ◽  
Electron Reduction ◽  
First Time

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

scholarly journals On the Proton-Bound Noble Gas Dimers (Ng-H-Ng)+ and (Ng-H-Ng')+ (Ng, Ng'= He-Xe): Relationships betweenStructure, Stability, and Bonding Character

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1305
Author(s):  
Stefano Borocci ◽  
Felice Grandinetti ◽  
Nico Sanna
Keyword(s):  
Theoretical Calculations ◽  
Noble Gas ◽  
Structure Stability ◽  
Covalent Bonds ◽  
Dissociation Energies ◽  
Non Covalent Interactions ◽  
The Difference ◽  
Noble Gas Dimers ◽  
Covalent Interactions ◽  
Cluster Level

The structure, stability, and bonding character of fifteen (Ng-H-Ng)+ and (Ng-H-Ng')+ (Ng, Ng' = He-Xe) compounds were explored by theoretical calculations performed at the coupled cluster level of theory. The nature of the stabilizing interactions was, in particular, assayed using a method recently proposed by the authors to classify the chemical bonds involving the noble-gas atoms. The bond distances and dissociation energies of the investigated ions fall in rather large intervals, and follow regular periodic trends, clearly referable to the difference between the proton affinity (PA) of the various Ng and Ng'. These variations are nicely correlated with the bonding situation of the (Ng-H-Ng)+ and (Ng-H-Ng')+. The Ng-H and Ng'-H contacts range, in fact, between strong covalent bonds to weak, non-covalent interactions, and their regular variability clearly illustrates the peculiar capability of the noble gases to undergo interactions covering the entire spectrum of the chemical bond.

scholarly journals A multicolor and ratiometric fluorescent sensing platform for metal ions based on arene–metal-ion contact

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Anna Kanegae ◽  
Yusuke Takata ◽  
Ippei Takashima ◽  
Shohei Uchinomiya ◽  
Ryosuke Kawagoe ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Near Infrared ◽  
Molecular Design ◽  
Theoretical Calculations ◽  
Probe Design ◽  
One Pot ◽  
Fluorescent Sensing ◽  
Sensing Platform ◽  
Ratiometric Detection

AbstractDespite continuous and active development of fluorescent metal-ion probes, their molecular design for ratiometric detection is restricted by the limited choice of available sensing mechanisms. Here we present a multicolor and ratiometric fluorescent sensing platform for metal ions based on the interaction between the metal ion and the aromatic ring of a fluorophore (arene–metal-ion, AM, coordination). Our molecular design provided the probes possessing a 1,9-bis(2′-pyridyl)-2,5,8-triazanonane as a flexible metal ion binding unit attached to a tricyclic fluorophore. This architecture allows to sense various metal ions, such as Zn(II), Cu(II), Cd(II), Ag(I), and Hg(II) with emission red-shifts. We showed that this probe design is applicable to a series of tricyclic fluorophores, which allow ratiometric detection of the metal ions from the blue to the near-infrared wavelengths. X-ray crystallography and theoretical calculations indicate that the coordinated metal ion has van der Waals contact with the fluorophore, perturbing the dye’s electronic structure and ring conformation to induce the emission red-shift. A set of the probes was useful for the differential sensing of eight metal ions in a one-pot single titration via principal component analysis. We also demonstrate that a xanthene fluorophore is applicable to the ratiometric imaging of metal ions under live-cell conditions.

scholarly journals Synthesis, Cytotoxic Activity, Crystal Structure, DFT Studies and Molecular Docking of 3-Amino-1-(2,5-dichlorophenyl)-8-methoxy-1H-benzo[f]chromene-2-carbonitrile

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 184
Author(s):  
Menna El Gaafary ◽  
Tatiana Syrovets ◽  
Hany M. Mohamed ◽  
Ahmed A. Elhenawy ◽  
Ahmed M. El-Agrody ◽  
...  
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Cancer Cell ◽  
Dna Methyltransferase ◽  
Human Cancer ◽  
Theoretical Calculations ◽  
Cancer Cell Lines ◽  
Molecular Structures ◽  
Cytotoxic Activities ◽  
X Ray

The target compound 3-amino-1-(2,5-d ichlorophenyl)-8-methoxy-1H-benzo[f]-chromene-2-carbonitrile (4) was synthesized via a reaction of 6-methoxynaphthalen-2-ol (1), 2,5-dichlorobenzaldehyde (2), and malononitrile (3) in ethanolic piperidine solution under microwave irradiation. The newly synthesized β-enaminonitrile was characterized by FT-IR, 1H NMR, 13C NMR, mass spectroscopy, elemental analysis and X-ray diffraction data. Its cytotoxic activity was evaluated against three different human cancer cell lines MDA-MB-231, A549, and MIA PaCa-2 in comparison to the positive controls etoposide and camptothecin employing the XTT cell viability assay. The analysis of the Hirshfeld surface was utilized to visualize the reliability of the crystal package. The obtained results confirmed that the tested molecule revealed promising cytotoxic activities against the three cancer cell lines. Furthermore, theoretical calculations (DFT) were carried out with the Becke3-Lee-Yang-parr (B3LYP) level using 6-311++G(d,p) basis. The optimization geometry for molecular structures was in agreement with the X-ray structure data. The HOMO-LUMO energy gap of the studied system was discussed. The intermolecular-interactions were studied through analysis of the topological-electron-density(r) using the QTAIM and NCI methods. The novel compound exhibited favorable ADMET properties and its molecular modeling analysis showed strong interaction with DNA methyltransferase 1.

Mullite Diffusion Barriers for SiC-C/C Composites Produced by Pulsed Laser Deposition

1998 ◽  
Vol 555 ◽  
Author(s):  
H. Fritze ◽  
A. Schnittker ◽  
T. Witke ◽  
C. Rüscher ◽  
S. Weber ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Target Material ◽  
High Energy ◽  
Single Step ◽  
Laser Deposition ◽  
Reduced Pressure ◽  
Oxidation Rates ◽  
Energy Impact ◽  
Diffusion Parameters

AbstractPulsed Laser Deposition (PLD) allows the ablation of nonconductive and high melting point target materials and the preparation of films with complex composition. High energy impact leads to melting and evaporation of the target material in a single step. In case of mullite ablation, the flux of the metal components is stoichiometric. Under reduced pressure the oxygen content in the layers decreases. However, after a short oxidation treatment, the formation of mullite in the coating is completed, as confirmed by IR spectroscopy and XRD investigations. For a commercial Si-SiC precoated C/C material, the effectiveness of additional PLD mullite layers as outer oxidation protection is tested in the temperature range 773 K < T < 1873 K. Mullite coatings with a thickness of 2.5 pm improve the oxidation behaviour significantly. Because of SiO2 formation at the mullite-SiC interface, all samples exhibited a mass increase upon oxidation. For oxidation durations of three days, only amorphous SiO2 is formed at the mullite-SiC interface. The inward diffusion of oxygen across the outer mullite-containing layer controls the kinetics of the reaction, as was deduced from 18O diffusivity measurements in PLD mullite layers. At temperatures close to the eutectic temperature (1860 K), mullite can seal defects. The calculated oxidation rates resulting from the diffusion parameters in SiO2 and mullite are close to the thermogravimetric data.

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