EFFECT OF SUBSTITUTION ON THE STRUCTURES AND OPTOELECTRONIC PROPERTIES OF MERCURY-CONTAINING DIETHYNYLFLUORENE

We report on a quantum-chemical study of the electronic and optical properties of Mercury(II) complexes HgTFT (1) and its electron-withdrawing substitutent HgTFOT (2), HgTFCNT (3) [where TFT = diethynylfluorenyl, TFOT = diethynylfluorenone and TFCNT = diethynyl-(9-(dicyanomethylene)fluorene)]. Our theoretical calculations indicate that the substitution of - CO , - C ( CN )2 for - CH in HgTFT significantly decreases the bond length alternation and increases the electron affinity, which would qualify HgTFOT 2 and HgTFCNT 3, especially 3, as candidates for n-type electrical conductors. The vertical transition energy associated with the low-lying excited state has been examined within the time-dependent DFT formalism for mercury diethynylfluorenyl derivatives. It is found that the electron-withdrawing substitutions lead to remarkable red shift in transition energy and alter the corresponding charge transfer manner.

Abinitio MRD-CI study of NO2. 1. Multi-dimensional potential surfaces for the two lowest 2A′ states

For a detailed theoretical abinitio study of the X2A1/A2B2 system of the NO2 molecule, three-dimensional potential energy surfaces have been calculated with the MRD-Cl method for both symmetric and asymmetric NO bond distances. The calculated data are given here together with the technical parameters of the respective treatment, and the main features of the surfaces are discussed. The geometrical locations and depths of the computed energy minima as well as the A–X vertical transition energy are found to be in good agreement with all known experimental data and allow for a good qualitative understanding of the overall appearance of the observed spectrum. The wavefunctions and potential energy surfaces will be used in subsequent investigations for the study of various molecular properties and coupling elements involved in the X2A1/A2B2 system of NO2.