A detailed investigation into the geometric and electronic structures of CoBQn (n = 2–10, Q = 0, −1) clusters

2017 ◽  
Vol 41 (19) ◽  
pp. 11208-11214 ◽  
Author(s):  
Peifang Li ◽  
Guoliang Sun ◽  
Jianping Bai ◽  
Weihua Wang ◽  
Gang Bao ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Size Dependence ◽  
Lumo Energy ◽  
Boron Clusters ◽  
Energy Gaps ◽  
Homo Lumo ◽  
Co Doped

The size dependence of HOMO–LUMO energy gaps of Co doped boron clusters.

Meso-alkynyl corroles and their cobalt(III), manganese(III) and gallium(III) complexes

2020 ◽  
Vol 24 (05n07) ◽  
pp. 737-749
Author(s):  
Michael Haas ◽  
Sabrina Gonglach ◽  
Wolfgang Schöfberger
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Theoretical Study ◽  
Lumo Energy ◽  
Functional Theory ◽  
Energy Gaps ◽  
Peak Broadening ◽  
Homo And Lumo ◽  
Homo Lumo

We report routes towards synthesis of novel [Formula: see text]-conjugated freebase cobalt, copper, gallium and manganese meso-alkynylcorroles. UV-vis spectra show that extensive peak broadening, red shifts, and changes in the oscillator strength of absorptions increase with the extension of [Formula: see text]-conjugation. Using density functional theory (DFT), we have carried out a first theoretical study of the electronic structure of these metallocorroles. Decreased energy gaps of about 0.3–0.4 eV between the HOMO and LUMO orbitals compared to the corresponding copper, gallium and manganese meso-5,10,15 triphenylcorrole are observed. In all cases, the HOMO energies are nearly unperturbed as the [Formula: see text]-conjugation is expanded. The contraction of the HOMO–LUMO energy gaps is attributed to the lowered LUMO energies.

Basis set effects on relative energies and HOMO–LUMO energy gaps of fullerene C36

2005 ◽  
Vol 113 (4) ◽  
pp. 233-237 ◽  
Author(s):  
Kyoung Hoon Kim ◽  
Young-Kyu Han ◽  
Jaehoon Jung
Keyword(s):  
Basis Set ◽  
Lumo Energy ◽  
Energy Gaps ◽  
Homo Lumo

Synthesis and characterization of a new meso-tetra-dihydro benzocyclobutacenaphthylene free-base porphyrin

2018 ◽  
Vol 22 (01n03) ◽  
pp. 173-180 ◽  
Author(s):  
Ümit İşci ◽  
Sevinc Zehra Topal ◽  
Emel Önal ◽  
İsmail Fidan ◽  
Savaş Berber ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Synthesis And Characterization ◽  
Free Base ◽  
Frontier Orbitals ◽  
Lumo Energy ◽  
Energy Gaps ◽  
Homo Lumo

A meso-tetra-6b,10b-dihydrobenzo[j]cyclobut[a]acenaphthylene free-base porphyrin was synthesised and its photophysical, photochemical and electrochemical properties were compared with those of free-base meso-tetraphenylporphyrin. The frontier orbitals and the HOMO–LUMO energy gaps of both compounds were also determined. It was demonstrated that the meso6b,10b-Dihydrobenzo[j]cyclobut[a]acenaphthylene porphyrin retained the same properties as the tetraphenylporphyrin.

A DFT study on the electronic and redox properties of [X8V14O50]n– (X = SiIV, GeIV, PV, and AsV)

2010 ◽  
Vol 88 (5) ◽  
pp. 434-442 ◽  
Author(s):  
Muhammad Ramzan Saeed Ashraf Janjua ◽  
Zhong-Min Su ◽  
Wei Guan ◽  
Ahmad Irfan ◽  
Shabbir Muhammad ◽  
...  
Keyword(s):  
Density Functional ◽  
Open Shell ◽  
Electronic Configuration ◽  
Redox Properties ◽  
Lumo Energy ◽  
Functional Theory ◽  
Energy Gaps ◽  
System 2 ◽  
System 1 ◽  
Homo Lumo

The electronic and redox properties of the title polyanions have been calculated by means of density functional theory (DFT). These were unrestricted open-shell systems with electronic configuration of d1 of V. In this behalf, energies and compositions of α-LUMO, β-LUMO, α-HOMO, and β-HOMO were also analyzed. First of all, electronic and redox properties of vanadosilicate [Si8V14O50]12– (system 1) were calculated and then SiIV was substituted with GeIV, PV, and AsV for further investigations of systems 2, 3, and 4, respectively. The substitution greatly modifies the electronic properties as α-LUMOs are quite different in all the studied systems. The α-LUMO is mainly composed of V and O in system 1, V and Ge in system 2, V and O in system 3, and As, O, and V in system 4. The alpha HOMO–LUMO energy gaps are greatly reduced in systems 2, 3, and 4 as compared with system 1. The system 4 [As8V14O50]4– has minimal value of total bonding energy, whereas system 2 [Ge8V14O50]12– has maximal, so energetically system 4 is more favourable than the others. After the first reduction, α-LUMO in [Si8V14O50]14– is made up of V and Si, β-LUMO in [Ge8V14O50]13– is concentrated on V and Ge, β-LUMO in [P8V14O50]5– is composed of V only, whereas β-LUMO in [As8V14O50]5– is delocalized over V, O, and As with almost the same contribution of all three atoms.

scholarly journals Density functional study of structures, stabilities and electronic properties of AgAunλ(λ=0,±1;n=1-12){\rm{AgAu}}_n^\lambda \left( {\lambda = 0, \pm 1;n = 1 - 12} \right) clusters: comparison with pure gold clusters

2020 ◽  
Vol 38 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Prabhat Ranjan ◽  
Tanmoy Chakraborty ◽  
Ajay Kumar
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Gold Clusters ◽  
Pure Gold ◽  
Functional Study ◽  
Bimetallic Clusters ◽  
Planar Geometry ◽  
Lumo Energy ◽  
Energy Gaps ◽  
Homo Lumo

AbstractGeometrical structures, relative stabilities and electronic properties of neutral, cationic and anionic pure gold {\rm{A}}u_{n + 1}^\lambda and Ag-doped bimetallic {\rm{AgAu}}_n^\lambda \left( {\lambda = 0, \pm 1;n = 1 - 12} \right) clusters have been systematically investigated by using density functional theory methodology. The optimized structures show that planar to three-dimensional structural transition occurs at n = 5 for cationic clusters. Due to strong relativistic effect of Au clusters, the ground state configurations of neutral and anionic bimetallic clusters favor planar geometry till n = 12. Silver atoms tend to occupy the most highly coordinated position and form the maximum number of bonds with Au atoms. The computed HOMO-LUMO energy gaps, fragmentation energies and second-order difference of energies show interesting odd-even oscillation behavior. The result indicates that AgAu5, {\rm{AgAu}}_2^ + and {\rm{AgAu}}_2^ - are the most stable clusters in this molecular system. The DFT based descriptors of bimetallic clusters are also discussed and compared with pure gold clusters. The high value of correlation coefficient between HOMO-LUMO energy gaps and DFT based descriptors supports our analysis. A good agreement between experimental and theoretical data has been obtained in this study.

Bithiophene-Fused Benzo[c]phospholes: Novel P,S-Containing Hybrid π-Conjugated Systems with Small HOMO–LUMO Energy Gaps

2008 ◽  
Vol 2008 (2) ◽  
pp. 255-259 ◽  
Author(s):  
Tooru Miyajima ◽  
Yoshihiro Matano ◽  
Hiroshi Imahori
Keyword(s):  
Lumo Energy ◽  
Conjugated Systems ◽  
Energy Gaps ◽  
Homo Lumo

Fluorinated Poly(N-vinylcarbazole) Host for Triplet Energy Confinement on Phosphorescent Emitter in Organic Light-emitting Diodes

2009 ◽  
Vol 1197 ◽  
Author(s):  
Yukitami Mizuno ◽  
Isao Takasu ◽  
Shuichi Uchikoga ◽  
Shintaro Enomoto ◽  
Tomoaki Sawabe ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Energy Gap ◽  
Organic Light Emitting Diodes ◽  
Lumo Energy ◽  
Light Emitting ◽  
Energy Gaps ◽  
Organic Light ◽  
Host Materials ◽  
Homo Lumo ◽  
Polymer Host

AbstractFluorinated carbazoles as host materials have been investigated for highly efficient organic light emitting diodes (OLEDs). By molecular orbital calculations, we found that fluorinations at position 2, 4, 5 and 7 of carbazole ring were effective for widening HOMO-LUMO energy gap. The energy gaps of our synthesized 2,7-difluorocarbazole (F2-Cz) and 2,4,5,7-tetrafluorocarbazole (F4-Cz), were estimated to be 3.71 eV and 3.87 eV by the absorption spectra, respectively. These energy gaps were higher than that of the non-substituted carbazole (Cz, 3.59 eV). We synthesized poly(N-vinyl-2,7-difluorocarbazole) (F2-PVK) and poly(N-vinyl-2,4,5,7-tetrafluorocarbazole) (F4-PVK) as solution processable polymer host materials. However, the F4-PVK was found to be an unsolved polymer. The F2-PVK could be compared with non substituted poly(N-vinylcarbazole) (PVK) in OLEDs. The emission layer (EML) contained iridium(III) bis [(4,6-di-fluorophenyl)-pyridinato-N,C2′] picolinate (FIrpic) as a blue phosphorescent dopant, and iridium(III) bis [2-(9,9-dihexylfluorenyl)-1-pyridine] acetylacetonate as a yellow dopant. The white OLED with the F2-PVK showed 1.4 times higher luminous current efficiency (24 cd/A) than the PVK (17 cd/A). These data show that the excitation energy is confined on dopants by using fluorinated polymer host material with higher T1 corresponding to wider HOMO-LUMO energy gap.

Mono- and Bi-nuclear Complexes of the Doubly Bidentate, Bridging Ligand 4,6-Di(2-pyridyl)pyrimidine.

1998 ◽  
Vol 51 (5) ◽  
pp. 371 ◽  
Author(s):  
Ian G. Phillips ◽  
Peter J. Steel
Keyword(s):  
Transition Metal Complexes ◽  
Binuclear Complexes ◽  
Two Dimensional ◽  
Lumo Energy ◽  
Metal Interactions ◽  
Bridging Ligand ◽  
Energy Gaps ◽  
Metal Metal ◽  
Homo Lumo ◽  
Metal Ligand

Thirteen mononuclear, homobinuclear and heterobinuclear transition metal complexes of 4,6-di(2- pyridyl)pyrimidine have been prepared. Assignments of the 1H n.m.r. spectra of the molybdenum(0) and ruthenium(II) complexes were achieved by a combination of one- and two-dimensional n.m.r. techniques, especially 1D-TOCSY. For the ruthenium complexes, electronic absorption spectroscopy and cyclic voltammetry were used to probe the nature of the metal{ligand and, for the binuclear complexes, metal-metal interactions. The complexes have low HOMO−LUMO energy gaps. Meta-metal interactions are shown to be of similar magnitude to those in complexes of the better-studied ligands 2,2′-bipyrimidine and 2,3-di(2-pyridyl)pyrazine.

scholarly journals Structural Properties and Nonlinear Optical Responses of Halogenated Compounds: A DFT Investigation on Molecular Modelling

2018 ◽  
Vol 16 (1) ◽  
pp. 978-985 ◽  
Author(s):  
Muhammad Ramzan Saeed Ashraf Janjua
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Study ◽  
Visible Region ◽  
Second Order ◽  
Computational Method ◽  
Lumo Energy ◽  
Functional Theory ◽  
Energy Gaps ◽  
Homo Lumo

AbstractComputational chemistry is used to evaluate structures of different compounds by using principles of theoretical and quantum chemistry integrated into useful computer programs. It is used to determine energies, dipole moments and thermodynamic properties of different compounds. The present work reports the computational study of six donor-acceptor dyes. The computational method CAM-B3LYP with 6-31G(d,p) was used in this research to determine the effect of halogens on non-linear optical compounds. HOMO-LUMO energy gaps, dipole polarizabilities, first hyperpolarizabilities, and absorption spectra of six studied compounds (dye 1: 4-(2-(4-fluorophenyl)ethynyl)benzenamine; dye 2: 4-(2-(4-chlorophenyl)ethynyl)benzenamine; dye 3: 4-(2-(4-bromophenyl)ethynyl)benzenamine; dye 4: 5-(2-(4-fluorophenyl)ethynyl)benzene-1,2,3-triamine; dye 5: 5-(2-(4-chlorophenyl)ethynyl)benzene-1,2,3-triamine; dye 6: 5-(2-(4-bromophenyl)ethynyl)benzene-1,2,3-triamine) with aniline and halo phenyl segments were computed by using density functional theory (DFT) and time-dependent density functional theory (TDDFT). Results indicate that all dyes showed wavelengths of maximum absorbance in the visible region. Small HOMO-LUMO energy gaps were observed in all investigated dyes. The present calculations on these dyes (1-6) offer an understanding of the direction of charge transfer (CT) and how NLO behavior can be explained. The aniline-to-halo phenyl CT, caused by the combination of the donor amino group and the acceptor halo group, could be a reason for NLO behavior of these sorts of compounds. These compounds exhibit significant molecular second-order NLO responses, especially dyes (6) and (5), with second-order polarizability determined to be approximately 4600 a.u.

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