Search

A systematic density functional theory (DFT) calculations is performed on the stabilities and electronic properties of two different structures [Csub.58][X.sub.18] and [C.sub.58][X.sub.1], where X = H, F, and Cl. It is seen that the large energy gaps between the highest occupied molecular orbitals and the lowest unoccupied molecular orbital and the aromatic character possess high stabilities.

A series of multiply N-confused porphyrins and their Zn and Cu complexes are investigated by using density functional theory (DFT) and ZINDO/SOS methods. The findings demonstrate that the multiply N-confused results have shown that the one-photon absorption (OPA) spectra of multiply N-confused porphyrins, along with their metal complexes and derivatives are promising molecules, which can be assembled series of materials with large two-photon absorption (TPA) cross sections.

A series of ferrocenyl derivatives with TCF-type acceptors are designed, and their electronic structures and one- and two-photon absorption properties are investigated. Results reveal that ferrocenyl derivatives with TCF-type acceptors are promising candidates for two-photon absorptions (TPA) materials.

Cationic cluster Ti2P6(super +) is studied within density functional theory. The structure of this cluster is predicted to be a slightly distorted tetragonal prism and the dissociation energy of this cationic cluster is higher than that of the known compound, [(P5)2Ti](super 2-), because of the different bonding in these two compounds.

All the oligomers investigated show less twisted structures compared with pristine polyflourene by incorporation of electron-donating 3,4-ethylenedioxythiophene (EDOT) or electron withdrawing pyridine and 1,3,4-oxadiozole moieties. All decisive molecular orbitals are delocalized on both subunits of the oligomers.

Quantum-chemical techniques are applied to investigate poly[10-(N-(2'-methyl)phenothiazine-3,7-diyl) and its fluorene copolymer poly[10-(N-(2'-methyl)phenothiazine-3,7-diyl)-co-alt-2,7-(9,9-dimenthylfluorene) and gain a detailed understanding the influence of phenothiazine units on the electronic and optical properties of fluorene derivatives. The result indicate that the incorporation with electron-donating moieties phenothiazine (PTZ) would reduce the band gaps of fluorene-based copolymers due to the highly nonplanar structure in PTZ, which resulting in the high HOMO energy level, and with the fractions of the PTZ increasing, the band gaps decrease.

The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICSs) of the ground state of P(sub 5)- anion, [Ti (mu(super 5)-P5)]- and sandwich complex [Ti(mu(super 5)-P5)(sub 2)](super 2-) are calculated. The results revealed that in each of the three molecules, the P-P and Ti-P bond distances are perfectly equal.

The photophysical properties, which vary X is varied, of Re (I)- halide complexes (X (sub 2)-bpy) ReECl (CO)(sub 3), are investigated using density functional theory (DFT). The electronic properties of the natural molecule, in addition to the positive and negative ions, are studied using B3LYP functional.

The AM1 and ZINDO methods were used to determine the equilibrium geometries, electronic structures, and one- and two-photon absorption properties of a series of paracyclophane derivatives. It was found that the molecular length played an important role in the one-photon absorption intensity and the two-photon absorption cross section.

A detailed investigation of the complex potential energy surface for the reaction of singlet methylene (CH2) with Nitrous oxide (N2O) using B3LYP/6-31G(d,p) and single point QCISD(T)/6-311G(d,p) methods is presented. This work can assist experiments to identify the products of the CH2+NO2 reaction.

The article explains the photophysical properties of bis-dipolar diphenylamino-endcapped oligoarylfluorenes, which are used as light-emitting diodes. Oligoarylfluorenes can be used as the hole and electron transport/injection materials in organic light-emitting diodes.

Density functional theory is used for investigating the electronic structures and stabilites of pure [M.sub.12.sup.-] and [Mn.sub.12.sup.2-]. The nucleus-independent chemical shift (NICS) predictions have indicated that larger basis sets including d-orbitals are required for analyzing the aromaticity of some main-group-metal-based clusters to obtain accurate predictions.

The 2385 classical isomers and four nonclassical isomers of fullerene C62 are studied. The relative stability under the interisomeric thermodynamic equilibrium is evaluated in terms of Gibbs function.

Several sum-over-state (SOS) experiments are used to study the molecular equilibrium, electronic and one- and two-photon absorption (TPA) properties of dipolar and octupolar [D.sub.2d] and [D.sub.3] bipyridyl metal complexes having different functionalized bipyridyl ligands. The analysis reveals that the maximum TPA wavelengths and the maximum cross sections of the metal complexes can be easily altered by the substitution of the various bonds.

Various researches are done to obtain certain theoretical, quantum-mechanical calculations to explain the optoelectric properties like photoexcitation, photoluminescence and electron transfer of organometallic compounds like gold(I) complex and its electron-withdrawing substituents. The analysis reveals that such substitutes considerably reduce the energy gap, leading to a red shift in its transition energy, which finds application in the development of a variety of substances like light-emitting diodies (LEDs).

Quantum-chemical techniques are applied to investigate a family of pi-conjugated polymers with substituted dimethoxy groups at the 3,6 positions of the fluorene ring, namely poly(2,7-(3,6-dimethoxy-fluorene) (PDMOF), poly(2,7-(3,6-dimethoxy-fluorene)-co-alt-fluorene (PDMOFF), and poly(2,7-(3,6-dimeth-oxy-fluorene)-co-alt-2,5-thiophene (PDMOFT). The influence of the presence of methoxy groups on the fluorene moiety on the ionization potential is emphasized.

Ground-and excited-state properties of the Re (I) halide bipyridine complex are studied. The B3LYP functional is used for this purpose.

The molecular equilibrium structures, electronic structures, and one- and two-photon absorption (TPA) properties of C2v(Zn(II), Fe(II) and Cu(I)) dipolar and D2d(Zn(II) and Cu(I)) and D3(Zn(II)) octupolar metal complexes featuring different functionalized bipyridyl ligands have been studied by the ZINDO-SOS method. The calculated results show that one- and two-photon absorption properties of metal complexes are strongly influenced by the nature of the ligands (donor end groups and linkers) and metal ions as well as by the symmetry of the complexes. The length of the -conjugated backbone, the Lewis acidity of the metal ions, and the increase of ligand-to-metal ratio result in a substantial enhancement of the TPA cross sections of metal complexes. Substitution of CN and NN for CC plays an important role in altering the maximum TPA wavelengths and the maximum TPA cross sections of metal complexes. Of them, the CN substituted metal complexes have relatively large TPA cross sections. Replacing styryl with thienylvinyl makes the one-photon absorption wavelength red shift and at the same time leads to a great decrease of the maximum TPA cross sections of metal complexes. The possible reason is discussed. In the range 500−1250 nm, octupolar metal complexes exhibit intense TPAs and therefore are promising candidates for TPA materials. [ABSTRACT FROM AUTHOR]