lumo energy
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Author(s):  
P. Periyannan ◽  
M. Beemarao ◽  
K . Karthik ◽  
S. Ponnuswamy ◽  
K. Ravichandran

In the title compound [systematic name: 1-(3-methyl-2,6-diphenylpiperidin-1-yl)ethanone], C20H23NO, the piperidine ring adopts a distorted boat conformation, while the phenyl rings subtend a dihedral angle 65.1 (2)°. In the crystal, molecules are linked by C—H...O hydrogen bonds into chains extending along the b-axis direction. The DFT/B3LYP/6–311 G(d,p) method was used to determine the HOMO–LUMO energy levels. A Hirshfeld surface analysis was conducted to verify the contributions of the different intermolecular interactions, indicating that the important contributions to the crystal packing are from H...H (73.2%), C...H (18.4%) and O...H (8.4%) interactions.


2021 ◽  
Vol 8 (4) ◽  
pp. 20218416
Author(s):  
Igor L. Nikonov ◽  
Leila K. Sadieva ◽  
Мaria I. Savchuk ◽  
Еkaterina S. Starnovskaya ◽  
Dmitry S. Kopchuk ◽  
...  

A rational approach to the synthesis of substituted naphtho[1,8-ef]perimidines based on SNH methodology and cyclization  reaction in the series of condensed azines with naphthalene substituents was presented. Photophysical properties of the obtained fluorophores were studied, in particular, green fluorescence in the 485–536 nm range with quantum yield up to 32.4% was detected. HOMO-LUMO energy values and distributions for the new compounds were calculated by the DFT method in comparison with nitroanalytes and perylene. Based on the data obtained, as well as on the results of fluorescence titration, the possibility of using the new diazaperylenes as potential chemosensors for the visual detection of nitro-containing explosives was shown.


Author(s):  
Elham Abdalrahem Bin Selim ◽  
Mohammed Hadi Al–Douh ◽  
Hassan Hadi Abdullah ◽  
Dahab Salim Al–Nohey

Two bis-Schiff Bases 1 and 2 are ligands that can coordinate with manganese metal to form stable complexes and have biological activity. Thermodynamic parameters, HOMO-LUMO energy levels and FTIR spectra of two ligands have been computed using B3LYP/6-311++G(d,p) functional of the DFT calculations. Both ligands are favored thermodynamically, and the ligand 1 has been shown to be more stable than ligand 2. The Polarizability values of two ligands have been investigated. The results refer that ligand 2 interacts earlier than ligand 1 to the metal ion. The FTIR spectra of two ligands have been evaluated. All results show the good agreement between the theoretical and experimental data.


Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7309
Author(s):  
Gulraiz Ahmad ◽  
Nasir Rasool ◽  
Adeel Mubarik ◽  
Ameer Fawad Zahoor ◽  
Muhammad Ali Hashmi ◽  
...  

Synthesis of 5-aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides (4a–4n) by a Suzuki cross-coupling reaction of 5-bromo-N-(pyrazin-2-yl)thiophene-2-carboxamide (3) with various aryl/heteroaryl boronic acids/pinacol esters was observed in this article. The intermediate compound 3 was prepared by condensation of pyrazin-2-amine (1) with 5-bromothiophene-2-carboxylic acid (2) mediated by TiCl4. The target pyrazine analogs (4a–4n) were confirmed by NMR and mass spectrometry. In DFT calculation of target molecules, several reactivity parameters like FMOs (EHOMO, ELUMO), HOMO–LUMO energy gap, electron affinity (A), ionization energy (I), electrophilicity index (ω), chemical softness (σ) and chemical hardness (η) were considered and discussed. Effect of various substituents was observed on values of the HOMO–LUMO energy gap and hyperpolarizability. The p-electronic delocalization extended over pyrazine, benzene and thiophene was examined in studying the NLO behavior. The chemical shifts of 1H NMR of all the synthesized compounds 4a–4n were calculated and compared with the experimental values.


Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1292
Author(s):  
Huai-Wen Tsai ◽  
Kan-Lin Hsueh ◽  
Mei-Hsin Chen ◽  
Che-Wun Hong

The electronic and optical properties of polythiophene (PT) for polymer light-emitting diodes (PLEDs) were calculated using density functional theory (DFT) and time-dependent DFT. We calculated the electronic and optical properties of thiophene and PT polymers with degrees of polymerization (DP) from 2 to 30 monomers (T1–T30) and their derivatives. The associated highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, band gaps, electron orbitals, and molecular structures were determined. As the DP increased, the LUMO energy gradually decreased, and the HOMO energy gradually increased. The band gap of PT approached 2 eV as the DP of the PT polymer increased from 1 to 30. The calculations and exchange–correlation functional were verified against values in the literature and experimental data from cyclic voltammetry (redox potential) and ultraviolet-visible, photoluminescence, and ultraviolet photoelectron spectra. The color of PT PLEDs can be adjusted by controlling the DP of the polymer and the substituents.


2021 ◽  
Vol 17 ◽  
pp. 2450-2461
Author(s):  
Najeh Tka ◽  
Mohamed Adnene Hadj Ayed ◽  
Mourad Ben Braiek ◽  
Mahjoub Jabli ◽  
Peter Langer

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.


Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1103
Author(s):  
Abdulrahman A. Alsimaree ◽  
Omar M. Alatawi ◽  
Paul G. Waddell ◽  
David P. Day ◽  
Nawaf I. Alsenani ◽  
...  

Two new pyrrolylquinoline-substituted heteroaromatic-containing compounds bearing a central boron bridge have been prepared by a short, high-yielding sequence consisting of Suzuki-coupling of 8-bromoquinoline and N-Boc 2-pyrroleboronic acid, thermolytic tert-butyloxycarbonyl deprotection, and subsequent boron chelation (either using boron trifluoride or triphenylborane). Both derivatives display longer wavelength absorption maxima (λabsmax) than a previously reported indolopyridine-BPh2 analogue, in agreement with the smaller HOMO-LUMO energy gap predicted by DFT quantum chemical calculations. Both of the pyrrolylquinoline-boron chelates display weak emission (quantum yields 0.3–0.9%) and the BPh2 complex displays a very broad, long-wavelength emission (λemmax = 715 nm, MeCN), which may be due to dimer emission and results in a large pseudo-Stokes’ shift (7753 cm−1) for this compound.


2021 ◽  
pp. 1-9
Author(s):  
Kun Harismah ◽  
Mohsen Mohammad Raei Nayini ◽  
Shadi Montazeri ◽  
Shaghayegh Ariaei ◽  
Milad Nouraliei

A huge number of parabens, esters of p-hydroxybenzoic acid, are used in cosmetic and personal care products as preservative substances. Due to their detrimental effects on ecosystem and human health, taking precautionary measures to remove these compounds is an important task regarding the environmental issues. In this study, a silica (SiO2) nanotube has been selected as a novel sensor to adsorb the most common parabens which are methyl paraben and propyl paraben molecules. To this aim, density functional theory (DFT) calculations were used to evaluate the properties for investigated compounds. The calculated adsorption energies of the most stable configurations for methyl parban@SiO2 and propyl paraben@SiO2 complexes were found to be –0.238 and –0.242 eV, respectively. The electronic properties of nanotubes experienced dramatic changes in case of interactions with parabens, which led to declining the HOMO/LUMO energy gap of the nanotube to its original value. Such adsorption could also enhance the electrical conductivity of the nanotubes meaning that the utilized SiO2 nanotube could detect the existence of methyl and propyl parabens molecules in the environment. As a concluding remark, the investigated SiO2 nanotube could work as a possible sensor for hazardous paraben with the importance of environmental issues.


Author(s):  
Younos Bouzian ◽  
Karim Chkirate ◽  
Joel T. Mague ◽  
Fares Hezam Al-Ostoot ◽  
Noureddine Hammou Ahabchane ◽  
...  

The title molecule, C20H15NO3, adopts a Z-shaped conformation with the carboxyl group nearly coplanar with the dihydroquinoline unit. In the crystal, corrugated layers are formed by C—H...O hydrogen bonds and are stacked by C—H...π(ring) interactions. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (43.3%), H...C/C...H (26.6%) and H...O/O...H (16.3%) interactions. The optimized structure calculated using density functional theory at the B3LYP/ 6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated HOMO–LUMO energy gap is 4.0319 eV.


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