where X1: S_aaN, X2: S_ssssSi, X3: LUMO
energy (au), X4: HOMO + LUMO
(au), X5: %H, X6: [S_sCH.
In most polymers, there is a large gap between the HOMO and LUMO
In addition, the surfaces of the HOMO and LUMO
calculated at the B3LYP/6-311 + G(3df,2pd) level are plotted in Fig.
Furthermore, the location of the HOMO and LUMO
for each complex, as determined via semi-empirical quantum mechanical calculations, can help predict the behavior of these ferrocene-alkyl chloride CTCs, which correlates well to the reported mechanism of radiative dissociation.
As a result, hydrogen bond formation between the cation and the carbonyl of the dienophile would stabilize the LUMO
energy of the acceptor, thus increasing the selectivity for formation of the endo product.
Small reducing agents approach the ketones from the face of the carbonyl moiety with the more accessible LUMO
site whereas bulky reducing agents approach the carbonyl from the less sterically hindered site.
Because we are not aware of a database with a sufficient number of experimentally derived properties (and some properties such as HOMO and LUMO
are not experimentally observable), we were not able to verify these calculations.
The HOMO and LUMO
energy levels of the materials are very crucial parameters for electroluminescence device configuration.
With less bulky reducing agents reduction takes place mainly from the face of the carbonyl carbon where the LUMO
is more accessible.
The main requirements of the materials are: (1) enough solubility for solution processability; (2) decreased LUMO
level (increased electron affinity) and HOMO level (to achieve air stability) with a low band gap; (3) highly organized microstructure with favourable molecular orbitals packing along the larger and planar pi-system direction.
]), the energies of HOMO and LUMO
of beta spin states ([E.
In most of the electroluminescent conjugated polymers such as PPV, hole injection, and transport are more favorable than electron injection and transport due to its high LUMO
energy level, which results an imbalance in the rates of electron and hole injection and thus lowering the device efficiency (16), (17).