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ABSTRACT: A systematic investigation of D3 C32 fullerene and its derivatives C32Xn (X = H and Cl) has been performed using B3LYP/6-31G(d) method based on the density functional theory. The geometry structures,
reaction energies, relative stabilities, and electronic properties have been studied. By investigating the possible C32Xn (X = H and Cl) molecules, C32H2 and C32Cl2 behave more thermodynamically accessible with respect to other derivatives. The frontier molecular orbitals and electronic
density of states calculations of C32X2 system indicate that H and Cl passivation have less contribution to the electronic structures, but significantly improve
the stability of D3 C32 fullerene. Finally, the 13C NMR chemical shifts of C32H2 and C32Cl2 have been simulated to provide helpful information for further experiment identification.
PACS68.35.bp Fullerenes-68.55.ap Fullerenes-73.61.Wp Fullerenes and related materials
The European Physical Journal D 04/2012; 53(2):197-204. · 1.48 Impact Factor
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ABSTRACT: Molecules with D-π-A structures are drawing increased attention for applications in organic electronic devices due to their distinct optoelectronic properties. A study of a new series of bipolar fluorophores that have been chemically modified for use as highly efficient nondoped blue organic light-emitting diodes (OLEDs) has been carried out based on existing molecular structures and a literature survey. The aim of this study is to provide a profound interpretation of the optical and electronic properties and the structure-property relationships of a series of new bipolar fluorophores. The study also aims to predict the photophysical and optoelectronic properties of the new fluorophores. The density functional theory (DFT) has been confirmed as reliable, especially in predicting the properties of unknown products. The geometry and the electronic structure of these molecules in the ground state were studied with DFT and ab initio HF, whereas the lowest singlet excited-state geometries were optimized by ab initio singlet configuration interaction (CIS). The absorption and emission spectra, both in the gas phase and in THF, and the lowest singlet excited energies were calculated by employing the time-dependent density functional theory (TDDFT) and the polarizable continuum model (PCM). To precisely predict the charge-transporting and charge-confining properties of the new fluorophores, three-layered devices have been simulated. The results show that the molecular geometries, HOMOs, LUMOs, energy gaps, ionization potentials (IP), electron affinities (EA), radiative lifetimes (τ), absorption and emission spectra are all tuned by chemical modifications with different π-conjugated bridges. The results also show that these molecular materials could be used as bipolar light-emitting materials for blue and deep-blue OLEDs.
Journal of molecular graphics & modelling 04/2012; 34:46-56. · 2.17 Impact Factor
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ABSTRACT: A comparative study using density functional theory (DFT) on the molecular structure, electronic structure and relative properties of 1,3,4-oxadiazole dimers 1,3-bis[2-(4-methylphenyl)-1,3,4-oxadiazol-5-yl]benzene (OXD-X) and its derivatives with alkoxy substituents -O(CH(2))(n-1)CH(3) (OXD-An, n=1, 2) and electron-withdrawing substituents -CN (OXD-C), -CF(3) (OXD-TFM), -NO(2) (OXD-N) added at meta-substitution in the phenyl ring are presented. The ground state structures of the title complexes are optimized at B3LYP/6-31G level of theory. In addition, the time dependent density functional theory (TDDFT) method is applied to calculate the absorption and emission spectra of the derivatives based on the ground state geometries. Comparing with the alkoxy substituents, the results show that the electron-withdrawing substituents have remarkable influences on the energy levels of the frontier molecular orbitals, the spectra and the transition compositions. Especially, -NO(2) group plays the prominent role and the fluorine improves the energy level of LUMO further. The experimental absorption wavelengths for OXD-X, OXD-A3 and OXD-A7 are well reproduced by the TDDFT technique. Moreover the absorption wavelengths and the transition compositions can be effectively adjusted through introducing electro-withdrawing groups in the phenyl ring. The reorganization energies for hole and electron are smaller than that of typical hole and electron transport materials.
Journal of molecular graphics & modelling 10/2009; 28(5):427-34. · 2.17 Impact Factor
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ABSTRACT: A direct dynamics method is employed to study the mechanism and kinetics of the hydrogen abstraction reaction of CH3OH with NCO. The optimized geometries and frequencies of the stationary points and the minimum-energy paths (MEPs) are obtained at the MP2/6-311G(d,p) level. In order to obtain more accurate potential energy surface (PES) information and provide more credible energy data for kinetic calculation, the single-point energies along the MEPs are further computed at QCISD(T)/6-311+G(d,p) and G3MP2 levels. The rate constants for two channels, the methyl-H abstraction channel and hydroxyl-H abstraction channel, are calculated by canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) contributions over the wide temperature region 220–1500 K. The theoretical overall rate constants are in good agreement with the available experimental data. For the title reaction, the methyl-H abstraction channel is dominant, while the hydroxyl-H abstraction channel is negligible over the whole temperature region.
Molecular Physics. 04/2007; 105(8):967-972.
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ABSTRACT: Based on the recently reported D(5h) C(50), the geometries and stabilities of its Saturn-like derivatives C(50)X(10) (X=F, Cl, Br) have been investigated by DFT method. Compared with C(50), the equatorial carbon atoms in C(50)X(10) have been saturated by halogens and change to sp(3) hybridization to release the large angle strain. Because the equatorial carbon atoms have been taken out of the pi system by the halogens "ring," the C(50)X(10) system has been split into two well-delocalized conjugated annulene subunits, and then the electronic stabilization has been enhanced.
The Journal of Chemical Physics 10/2005; 123(9):94305. · 3.33 Impact Factor
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ABSTRACT: The electronic structures and geometries of all even carbon fullerenes were investigated theoretically using density functional theory (DFT) at the B3LYP/6-31G* level. Based on geometries, energies, and aromaticities, the potential relationship between geometry factors and stability has been investigated systematically. The extra stability of C60 has been confirmed by the shorter average bond length, smaller angle strain, widest energy gap, larger binding energy, and dissociation energy. Furthermore, C32 and C50 are predicted to have higher aromaticity due to larger negative nucleus independent chemical shift (NICS) values, whereas C60 displays a weak aromaticity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
International Journal of Quantum Chemistry 06/2005; 105(2):142 - 147. · 1.36 Impact Factor
