scholarly journals Synthesis, photophysical and electrochemical properties of pyridine, pyrazine and triazine-based (D–π–)2A fluorescent dyes

2019 ◽  
Vol 15 ◽  
pp. 1712-1721 ◽  
Author(s):  
Keiichi Imato ◽  
Toshiaki Enoki ◽  
Koji Uenaka ◽  
Yousuke Ooyama
Keyword(s):  
Cyclic Voltammetry ◽  
Energy Level ◽  
Electrochemical Properties ◽  
Density Functional ◽  
Fluorescent Dyes ◽  
Stokes Shift ◽  
Solvent Polarity ◽  
Polar Solvents ◽  
Lumo Energy ◽  
Fluorescence Maximum

The donor–acceptor–π-conjugated (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 with two (diphenylamino)carbazole thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and a pyridine, pyrazine or triazine ring as electron-withdrawing group (electron-accepting group, A) have been designed and synthesized. The photophysical and electrochemical properties of the three dyes were investigated by photoabsorption and fluorescence spectroscopy, Lippert–Mataga plots, cyclic voltammetry and density functional theory calculations. The photoabsorption maximum (λmax,abs) and the fluorescence maximum (λmax,fl) for the intramolecular charge-transfer characteristic band of the (D–π–)2A fluorescent dyes show bathochromic shifts in the order of OUY-2 < OUK-2 < OUJ-2. Moreover, the photoabsorption bands of the (D–π–)2A fluorescent dyes are nearly independent of solvent polarity, while the fluorescence bands showed bathochromic shifts with increasing solvent polarity (i.e., positive fluorescence solvatochromism). The Lippert–Mataga plots for OUY-2, OUK-2 and OUJ-2 indicate that the Δμ (= μe − μg) value, which is the difference in the dipole moment of the dye between the excited (μe) and the ground (μg) states, increases in the order of OUY-2 < OUK-2 < OUJ-2. Therefore, the fact explains our findings that OUJ-2 shows large bathochromic shifts of the fluorescence maxima in polar solvents, as well as the Stokes shift values of OUJ-2 in polar solvents are much larger than those in nonpolar solvents. The cyclic voltammetry of OUY-2, OUK-2 and OUJ-2 demonstrated that there is little difference in the HOMO energy level among the three dyes, but the LUMO energy levels decrease in the order of OUY-2 > OUK-2 > OUJ-2. Consequently, this work reveals that for the (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 the bathochromic shifts of λmax,abs and λmax,fl and the lowering of the LUMO energy level are dependent on the electron-withdrawing ability of the azine ring, which increases in the order of OUY-2 < OUK-2 < OUJ-2.

scholarly journals Synthesis and Photophysical and Electrochemical Properties of Pyridine-, Pyrazine- and Triazine-based (D-π-)2A Fluorescent Dyes

2019 ◽  
Author(s):  
Keiichi Imato ◽  
Toshiaki Enoki ◽  
Koji Uenaka ◽  
Yousuke Ooyama
Keyword(s):  
Cyclic Voltammetry ◽  
Energy Level ◽  
Electrochemical Properties ◽  
Density Functional ◽  
Fluorescent Dyes ◽  
Bathochromic Shift ◽  
Stokes Shift ◽  
Solvent Polarity ◽  
Polar Solvents ◽  
Lumo Energy

Donor–acceptor–π-conjugated (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 with two (diphenylamino)carbazole-thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and a pyridine, pyrazine or triazine ring as electron-withdrawing group (electron-accepting group; A) have been designed and developed and their photophysical and electrochemical properties were investigated based on the photoabsorption and fluorescence spectroscopy, Lippert–Mataga plots, cyclic voltammetry and density functional theory calculations. The photoabsorption maximum (λ abs max) and the fluorescence maximum (λ fl max) for the intramolecular charge-transfer characteristic band of the (D–π–)2A fluorescent dyes show bathochromic shift in the order of OUY-2 < OUK-2 < OUJ-2. Moreover, the photoabsorption spectra of the (D–π–)2A fluorescent dyes are nearly independent of solvent polarity, while their fluorescence maxima bathochromically shifted with increasing solvent polarity (i.e., positive fluorescence solvatochromism). The Lippert–Mataga plots for OUY-2, OUK-2 and OUJ-2 indicate that the Δμ (= μ e ‒ μ g) value, which is the difference in the dipole moment of the dye between the excited (μ e) and the ground (μ g) states, increases in the order of OUY-2 < OUK-2 < OUJ-2, that is, the fact explains our findings that OUJ-2 shows large bathochromic shifts in their fluorescence maxima in polar solvents and that the Stokes shift values for OUJ-2 in polar solvents are much larger than those in nonpolar solvents. The cyclic voltammetry of OUY-2, OUK-2 and OUJ-2 demonstrated that there is little difference in the HOMO energy level among the three dyes, but the LUMO energy levels decrease in the order of OUY-2 > OUK-2 > OUJ-2. Consequently, this work reveals that for the (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 the bathochromic shifts of λ abs max and λ fl max and the lowering of the LUMO energy level are dependent on the electron-withdrawing ability of azine ring, which increases in the order of OUY-2 < OUK-2 < OUJ-2.

CHAMELEON GROUND STATE AND EXCITED STATES OF EDT-TTF-IM-F4TCNQ RADICAL DYAD IN DIFFERENT ENVIRONMENTS

2012 ◽  
Vol 11 (03) ◽  
pp. 505-525 ◽  
Author(s):  
YUHUA ZHOU ◽  
KAI TAN ◽  
XIN LU
Keyword(s):  
Charge Transfer ◽  
Solid State ◽  
Excited States ◽  
Ground State ◽  
Density Functional ◽  
Solvent Polarity ◽  
Functional Study ◽  
Polar Solvents ◽  
Model Calculations ◽  
A Charge

We have performed a systematic density functional study on the ground-state electronic structure and excited states of a representative D-σ-A dyad, i.e. EDT-TTF-Im-F4TCNQ π-radical, in vacuo and in different conventional solvents (toluene, THF, DMF and DMSO) by using some popular hybrid density functionals (B3LYP, M05, M05-2X, PBE0 and BMK). It has been shown that the M05 and B3LYP functionals perform the best in predicting the intramolecular charge-transfer (ICT) pertaining to both the ground state and excited states of the dyad. The amphoteric dyad is liable to solvent-promoted ICT from its EDT-TTF-Im donor (D) to F4TCNQ acceptor (A), adopting a charge-unseparated ground state D-A• in vacuo, a partially zwitterionic ground state [D-A]• in nonpolar toluene solvent, and a fully zwitterionic ground state D•+-A- in such polar solvents as THF, DMF and DMSO. Owing to its solvent-dependent chameleon ground state, excited states of the dyad in solvents also exhibit remarkable dependence on solvent polarity, as revealed by TDDFT calculations. Furthermore, cluster model calculations revealed that intermolecular charge-transfer readily occurs between the dyads, accounting for the observed zwitterionic charge state in solid state and solid-state semiconductivity.

scholarly journals Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

2021 ◽  
Vol 17 ◽  
pp. 2450-2461
Author(s):  
Najeh Tka ◽  
Mohamed Adnene Hadj Ayed ◽  
Mourad Ben Braiek ◽  
Mahjoub Jabli ◽  
Peter Langer
Keyword(s):  
Density Functional Theory ◽  
Cyclic Voltammetry ◽  
Density Functional ◽  
Energy Levels ◽  
Cross Coupling ◽  
Density Functional Theory Calculations ◽  
Facile Synthesis ◽  
Lumo Energy ◽  
Functional Theory ◽  
Homo Lumo

A facile synthesis of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridine derivatives is reported which is based on POCl3-mediated cyclodehydration followed by double Suzuki–Miyaura cross-coupling. The absorption and fluorescence properties of the obtained products were investigated and their HOMO/LUMO energy levels were estimated by cyclic voltammetry measurements. Besides, density functional theory calculations were carried out for further exploration of their electronic properties.

Synthesis and photophysical study of new blue fluorescent poly(azomethine-1,3,4-oxadiazole)s containing dimethylamino groups

2017 ◽  
Vol 30 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Elena Hamciuc ◽  
Mihaela Homocianu ◽  
Corneliu Hamciuc ◽  
Ionela-Daniela Carja
Keyword(s):  
Stokes Shift ◽  
Solvent Polarity ◽  
Decomposition Temperature ◽  
Photoluminescence Spectra ◽  
Polar Solvents ◽  
Initial Decomposition Temperature ◽  
Yield Values ◽  
Photophysical Study ◽  
Hcl Concentration ◽  
Terephthalic Aldehyde

New aromatic polyazomethines were synthesized by polycondensation reaction of a diamine containing 1,3,4-oxadiazole ring, namely, 4,4′-diamino-4″-[2-(4-phenoxy)-5-(4-dimethylaminophenyl)-1,3,4-oxadiazole)]triphenylmethane, with terephthalic aldehyde or bis(4-formylphenoxyphenyl)fluorene, by using N-methyl-2-pyrrolidinone (NMP) as solvent. The polymers were easily soluble in polar solvents, such as NMP, N, N-dimethylacetamide, or chloroform, and showed high thermal stability with the initial decomposition temperature above 415°C and the temperature of 10% weight loss in the range of 450–460°C. They exhibited high char yield at 800°C in the range of 52–56%. Optical properties were studied by absorption and photoluminescence spectra. In solution, the polymers presented two absorption maxima in the ranges 273–278 and 330–346 nm and emitted violet-blue light in the range of 413–468 nm, depending on the solvent polarity. The Stokes shift and emission quantum yield values depend on the polymer structure and solvent polarity. The emission intensity in NMP solution was enhanced upon increasing the HCl concentration, while the absorption spectral profile was slightly influenced.

scholarly journals Effect of Deposition Parameters on Electrochemical Properties of Polypyrrole-Graphene Oxide Films

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 624 ◽  
Author(s):  
Alina Iuliana Pruna ◽  
Nelly Ma. Rosas-Laverde ◽  
David Busquets Mataix
Keyword(s):  
Cyclic Voltammetry ◽  
Graphene Oxide ◽  
Electrochemical Properties ◽  
Sodium Dodecyl ◽  
Hybrid Coatings ◽  
Deposition Parameters ◽  
Structure Morphology ◽  
Energy Storage Applications ◽  
Improved Performance ◽  
Sds Surfactant

Graphene oxide (GO)-modified polypyrrole (PPy) coatings were obtained by electrochemical methods in the presence of the anionic surfactant, sodium dodecyl sulfate (SDS). The structure, morphology, and electrochemical properties of the coatings were assessed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry at varying scan rates, respectively. The properties of the obtained coatings were analyzed with the GO and PPy loadings and electrodeposition mode. The hybrid coatings obtained galvanostatically showed a coarser appearance than those deposited by cyclic voltammetry CV mode and improved performance, respectively, which was further enhanced by GO and PPy loading. The capacitance enhancement can be attributed to the SDS surfactant that well dispersed the GO sheets, thus allowing the use of lower GO content for improved contribution, while the choice of suitable electrodeposition parameters is highly important for improving the applicability of GO-modified PPy coatings in energy storage applications.

scholarly journals Research on Molecular Structure and Electronic Properties of Ln3+ (Ce3+, Tb3+, Pr3+)/Li+ and Eu2+ Co-Doped Sr2Si5N8 via DFT Calculation

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1849
Author(s):  
Ziqian Yin ◽  
Meijuan Li ◽  
Jianwen Zhang ◽  
Qiang Shen
Keyword(s):  
Molecular Structure ◽  
Energy Level ◽  
Density Functional ◽  
Formation Energy ◽  
Electronic Band Structure ◽  
Blue Shift ◽  
Lanthanide Ions ◽  
Partial Replacement ◽  
Electronic Band ◽  
Charge Imbalance

We use density functional theory (DFT) to study the molecular structure and electronic band structure of Sr2Si5N8:Eu2+ doped with trivalent lanthanides (Ln3+ = Ce3+, Tb3+, Pr3+). Li+ was used as a charge compensator for the charge imbalance caused by the partial replacement of Sr2+ by Ln3+. The doping of Ln lanthanide atom causes the structure of Sr2Si5N8 lattice to shrink due to the smaller atomic radius of Ln3+ and Li+ compared to Sr2+. The doped structure’s formation energy indicates that the formation energy of Li+, which is used to compensate for the charge imbalance, is the lowest when the Sr2 site is doped. Thus, a suitable Li+ doping site for double-doped lanthanide ions can be provided. In Sr2Si5N8:Eu2+, the doped Ce3+ can occupy partly the site of Sr12+ ([SrN8]), while Eu2+ accounts for Sr12+ and Sr22+ ([SrN10]). When the Pr3+ ion is selected as the dopant in Sr2Si5N8:Eu2+, Pr3+ and Eu2+ would replace Sr22+ simultaneously. In this theoretical model, the replacement of Sr2+ by Tb3+ cannot exist reasonably. For the electronic structure, the energy level of Sr2Si5N8:Eu2+/Li+ doped with Ce3+ and Pr3+ appears at the bottom of the conduction band or in the forbidden band, which reduces the energy bandgap of Sr2Si5N8. We use DFT+U to adjust the lanthanide ion 4f energy level. The adjusted 4f-CBM of CeSr1LiSr1-Sr2Si5N8 is from 2.42 to 2.85 eV. The energy range of 4f-CBM in PrSr1LiSr1-Sr2Si5N8 is 2.75–2.99 eV and its peak is 2.90 eV; the addition of Ce3+ in EuSr1CeSr1LiSr1 made the 4f energy level of Eu2+ blue shift. The addition of Pr3+ in EuSr2PrSr2LiSr1 makes part of the Eu2+ 4f energy level blue shift. Eu2+ 4f energy level in EuSr2CeSr1LiSr1 is not in the forbidden band, so Eu2+ is not used as the emission center.

Exploring the possibilities of two-dimensional transition metal carbides as anode materials for sodium batteries

2015 ◽  
Vol 17 (7) ◽  
pp. 5000-5005 ◽  
Author(s):  
Eunjeong Yang ◽  
Hyunjun Ji ◽  
Jaehoon Kim ◽  
Heejin Kim ◽  
Yousung Jung
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Electrochemical Properties ◽  
Anode Materials ◽  
Density Functional ◽  
Two Dimensional ◽  
Metal Carbides ◽  
Functional Theory ◽  
Transition Metal Carbides ◽  
Sodium Batteries

MXenes are predicted to be a family of promising Na anode materials with desirable electrochemical properties using density functional theory.

Preparation and Electrochemical Properties of LaMnO3 Powder as a Supercapacitor Electrode Material

2017 ◽  
Vol 727 ◽  
pp. 698-704 ◽  
Author(s):  
Xian Wei Wang ◽  
Xiao Er Wang ◽  
Hui Chao Zhang ◽  
Qian Qian Zhu ◽  
Dong Li Zheng ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Properties ◽  
Electrode Material ◽  
Raw Materials ◽  
Sol Gel ◽  
Galvanostatic Charge ◽  
Supercapacitor Electrode ◽  
Lanthanum Manganate ◽  
Pure Phase ◽  
Charge Discharge

The structural and electrochemical properties of lanthanum manganate (LaMnO3) powder prepared by the sol-gel method are researched in this article. The powder calcined at 600 °C showed amorphous, and the powder calcined at 700-800 °C showed the pure phase of the LaMnO3. The grains with the size of about 80-120 nm were agglomerating together. Cyclic voltammetry and galvanostatic charge-discharge were used to characterize the electrochemical properties in alkaline environment. The electrochemical properties calcined at 700 °C showed a specific capacitance of 73 F/g at the current density of 0.5 A/g. The raw materials for preparing the LaMnO3 powder are cheap, and the operation method is simple.

STRUCTURES, ABSORPTION SPECTRA, AND ELECTRONIC PROPERTIES OF POLYFLUORENE AND ITS DERIVATIVES: A THEORETICAL STUDY

2006 ◽  
Vol 05 (03) ◽  
pp. 595-608 ◽  
Author(s):  
KRIENGSAK SRIWICHITKAMOL ◽  
SONGWUT SURAMITR ◽  
POTJAMAN POOLMEE ◽  
SUPA HANNONGBUA
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Level Energy ◽  
Excitation Energies ◽  
Lumo Energy ◽  
Functional Theory ◽  
Local Energy Minimum ◽  
Pi Systems ◽  
Homo Lumo

The structural and energetic properties of polyfluorene and its derivatives were investigated, using quantum chemical calculations. Conformational analysis of bifluorene was performed by using ab initio (HF/6-31G* and MP2/6-31G*) and density functional theory (B3LYP/6-31G*) calculations. The results showed that the local energy minimum of bifluorene lies between the coplanar and perpendicular conformation, and the B3LYP/6-31G* calculations led to the overestimation of the stability of the planar pi systems. The HOMO-LUMO energy differences of fluorene oligomers and its derivatives — 9,9-dihexylfluorene (DHPF), 9,9-dioctylfluorene (PFO), and bis(2-ethylhexyl)fluorene (BEHPF) — were calculated at the B3LYP/6-31G* level. Energy gaps and effective conjugation lengths of the corresponding polymers were obtained by extrapolating HOMO-LUMO energy differences and the lowest excitation energies to infinite chain length. The lowest excitation energies and the maximum absorption wavelength of polyfluorene were also performed, employing the time-dependent density functional theory (TDDFT) and ZINDO methods. The extrapolations, based on TDDFT and ZINDO calculations, agree well with experimental results. These theoretical methods can be useful for the design of new polymeric structures with a reducing energy gap.

Synthesis and Characterization of a Methanofullerene-4-Fluoro-α-Cyanostilbene Dyad as a Potential Acceptor for Organic Solar Cells

2015 ◽  
Vol 1784 ◽  
Author(s):  
Venkata Neti
Keyword(s):  
Mass Spectrometry ◽  
Cyclic Voltammetry ◽  
Solar Cells ◽  
Organic Solar Cells ◽  
Synthesis And Characterization ◽  
Lumo Energy ◽  
Homo Lumo ◽  
Aryl Ester

ABSTRACTA series of fluorine appended highly conjugated fullerenes were prepared containing fluoro-α-cyanostilbene and aryl ester units. These modified PCBM dyads are fully characterized by NMR, Mass spectrometry, UV-vis, and cyclic voltammetry (Figures 1-4). It was found that the presence of fluoro-α-cyanostilbenes and esters affects the cyclic voltammetry and absorption in the UV-Vis region. The PCBA modified fullerenes significantly influences the HOMO-LUMO energy and wide absorption compared to PCBM.

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