A Graph-theoretical Analysis of the HOMO-LUMO Separation in Conjugated Hydrocarbons

1974 ◽  
Vol 29 (1-2) ◽  
pp. 80-82 ◽  
Author(s):  
I. Gutman ◽  
J. V. Knop ◽  
N. Trinajstić
Keyword(s):  
Theoretical Analysis ◽  
Energy Gap ◽  
Membered Ring ◽  
Lumo Energy ◽  
Graph Theoretical Analysis ◽  
Conjugated Hydrocarbons ◽  
Homo Lumo

Graph-theoretical rules concerning the HOMO-LUMO separation in conjugated hydrocarbons are given. It has been found that a closure of odd-membered rings will not essentially change the HOMO-LUMO energy gap (ΔΕ). However, ΔΕ will be shifted down or up depending whether a (4m + 1)-or (4m + 3)-ring is closed. A closure of an even-membered ring increase the value of ΔΕ in the case of (4m + 2)- and decrease ΔΕ value in the case of (4m)-cycles if delocalized rings are formed. The effect is opposite if quinonoid rings are generated.

Direct Observation of a Lattice-Framework Silylene:  A Planar Four-Membered-Ring Dialkylsilylene with a Small HOMO−LUMO Energy Gap

2006 ◽  
Vol 25 (5) ◽  
pp. 1325-1328 ◽  
Author(s):  
Eunsang Kwon ◽  
Hiromasa Tanaka ◽  
Takayuki Makino ◽  
Shinobu Tsutsui ◽  
Shigeki Matsumoto ◽  
...  
Keyword(s):  
Direct Observation ◽  
Energy Gap ◽  
Membered Ring ◽  
Lumo Energy ◽  
Homo Lumo

The six-membered-ring azomethineN-((E)-{5-[(E)-(pyridin-3-ylimino)methyl]thiophen-2-yl}methylidene)pyridin-3-amine

2013 ◽  
Vol 69 (10) ◽  
pp. 1196-1199 ◽  
Author(s):  
Andréanne Bolduc ◽  
Stéphane Dufresne ◽  
W. G. Skene
Keyword(s):  
Energy Gap ◽  
Three Dimensional ◽  
Energy Difference ◽  
Membered Ring ◽  
Intermolecular Hydrogen Bonding ◽  
Lumo Energy ◽  
Azomethine Group ◽  
Compound C ◽  
The Mean ◽  
Homo Lumo

The title compound, C16H12N4S, forms a three-dimensional layered network structureviaintermolecular hydrogen bonding and π-stacking. The azomethine molecule adopts the thermodynamically stableEregioisomer and the pyridine substituents are antiperiplanar. The mean planes of the pyridine rings and the azomethine group to which they are connected are twisted by 27.27 (5) and 33.60 (5)°. The electrochemical energy gap of 2.3 eV based on the HOMO–LUMO energy difference is in agreement with the spectroscopically derived value.

A p–n fusion strategy to design bipolar organic materials for high-energy-density symmetric batteries

2021 ◽  
Author(s):  
Jihyeon Kim ◽  
Heechan Kim ◽  
Sechan Lee ◽  
Giyun Kwon ◽  
Taewon Kang ◽  
...  
Keyword(s):  
Energy Density ◽  
Organic Material ◽  
Energy Gap ◽  
High Energy ◽  
High Energy Density ◽  
Lumo Energy ◽  
Fusion Strategy ◽  
Redox Active ◽  
Bipolar Type ◽  
Homo Lumo

A new bipolar-type redox-active organic material with a wide HOMO–LUMO energy gap is designed though the ‘p–n fusion’ strategy.

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.

scholarly journals 5-Methyl-1,3-phenylene bis[5-(dimethylamino)naphthalene-1-sulfonate]: crystal structure and DFT calculations

2019 ◽  
Vol 75 (7) ◽  
pp. 1079-1083
Author(s):  
Tanwawan Duangthongyou ◽  
Ramida Rattanakam ◽  
Kittipong Chainok ◽  
Songwut Suramitr ◽  
Thawatchai Tuntulani ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Energy Gap ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Hydrogen Atoms ◽  
Lumo Energy ◽  
Compound C ◽  
Dansyl Group ◽  
Weak Hydrogen Bonds ◽  
Homo Lumo

The title compound, C31H30N2S2O6, possesses crystallographically imposed twofold symmetry with the two C atoms of the central benzene ring and the C atom of its methyl substituent lying on the twofold rotation axis. The two dansyl groups are twisted away from the plane of methylphenyl bridging unit in opposite directions. The three-dimensional arrangement in the crystal is mainly stabilized by weak hydrogen bonds between the sulfonyl oxygen atoms and the hydrogen atoms from the N-methyl groups. Stacking of the dansyl group is not observed. From the DFT calculations, the HOMO–LUMO energy gap was found to be 2.99 eV and indicates n→π* and π→π* transitions within the molecule.

SOLVENT EFFECTS ON THE ELECTRONIC STRUCTURE AND NON-LINEAR OPTICAL PROPERTIES OF PYRENE AND SOME OF ITS DERIVATIVES BASED ON DENSITY FUNCTIONAL THEORY

2021 ◽  
Vol 4 (4) ◽  
pp. 236-251
Author(s):  
A. S. Gidado ◽  
L. S. Taura ◽  
A. Musa
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Basis Set ◽  
Lumo Energy ◽  
Functional Theory ◽  
Organic Optoelectronic ◽  
Homo Lumo

Pyrene (C16H10) is an organic semiconductor which has wide applications in the field of organic electronics suitable for the development of organic light emitting diodes (OLED) and organic photovoltaic cells (OPV). In this work, Density Functional Theory (DFT) using Becke’s three and Lee Yang Parr (B3LYP) functional with basis set 6-311++G(d, p) implemented in Gaussian 03 package was  used to compute total energy, bond parameters, HOMO-LUMO energy gap, electron affinity, ionization potential, chemical reactivity descriptors, dipole moment, isotropic polarizability (α), anisotropy of polarizability ( Δ∝) total first order hyper-polarizability () and second order hyperpolarizability (). The molecules used are pyrene, 1-chloropyrene and 4-chloropyrene  in gas phase and in five different solvents: benzene, chloroform, acetone, DMSO and water. The results obtained show that solvents and chlorination actually influenced the properties of the molecules. The isolated pyrene in acetone has the largest value of HOMO-LUMO energy gap of and is a bit closer to a previously reported experimental value of  and hence is the most stable. Thus, the pyrene molecule has more kinetic stability and can be described as low reactive molecule. The calculated dipole moments are in the order of 4-chloropyrene (1.7645 D) < 1-chloropyrene (1.9663 D) in gas phase. The anisotropy of polarizability ( for pyrene and its derivatives were found to increase with increasing polarity of the solvents.  In a nutshell, the molecules will be promising for organic optoelectronic devices based on their computed properties as reported by this work.

HOMO–LUMO Energy-Gap Tuning of π-Conjugated Zwitterions Composed of Electron-Donating Anion and Electron-Accepting Cation

2020 ◽  
Vol 86 (1) ◽  
pp. 770-781
Author(s):  
Akihiro Shimizu ◽  
Yu Ishizaki ◽  
Shun Horiuchi ◽  
Takashi Hirose ◽  
Kenji Matsuda ◽  
...  
Keyword(s):  
Energy Gap ◽  
Lumo Energy ◽  
Homo Lumo

Strategic design of thiophene-fused nickel dithiolene derivatives for efficient NLO response

2018 ◽  
Vol 20 (28) ◽  
pp. 19007-19016 ◽  
Author(s):  
Manoj Majumder ◽  
Anirban Misra
Keyword(s):  
Energy Gap ◽  
First Hyperpolarizability ◽  
Lumo Energy ◽  
Strategic Design ◽  
Nlo Response ◽  
Acceptor Group ◽  
Donor Acceptor ◽  
Homo Lumo

The zwitterionic donor–acceptor group significantly reduces the HOMO–LUMO energy gap resulting in an enormous increase in the first hyperpolarizability values.

scholarly journals Trans influence and substituent effects on the HOMO-LUMO energy gap and Stokes shift in Ru mono-diimine derivatives

2019 ◽  
Vol 1195 ◽  
pp. 620-631 ◽  
Author(s):  
Sanaa AlAbbad ◽  
Tova Sardot ◽  
Oliko Lekashvili ◽  
Daniel Decato ◽  
Francesco Lelj ◽  
...  
Keyword(s):  
Energy Gap ◽  
Stokes Shift ◽  
Substituent Effects ◽  
Lumo Energy ◽  
Trans Influence ◽  
Homo Lumo
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