Electrostatic interactions as a factor in the determination of the HOMO in the liquid state

Abstract

An ellipsoidal cavity model has been used to study the energy changes in occupied molecular orbitals induced by solute–solvent electrostatic interactions. Some benzene derivatives have been selected as solutes. Calculations have been carried out at the CNDO and abinitio STO-4G levels. Important variations in the molecular orbital sequence, involving a change in the HOMO nature, have been observed. A perturbation analysis is employed to understand the orbital evolution from gas phase to solution.

Theoretical investigation of solvent and oxidation/deprotonation effects on the electronic structure of a mononuclear Ru-aqua-polypyridine complex in aqueous solution

“…Such destabilizing orbitals effect can happen, for example, when the FMOs dipole moments do not have the same direction as the molecular dipole moment, thus inducing a destabilizing effect. 89 Conversely, the H(or S)OMO and LUMO orbitals stability are also connected to the total charges of the Ru-complex species. In solution, the H(or S)OMO (and LUMO) energies are −5.02 (−2.44), −6.11 (−2.73), −7.12 (−2.96), −7.05 (−3.03), −7.92 (−3.37) eV for [Ru II (OH)] + , [Ru II (H 2 O)] 2+ , [Ru III (OH)] 2+ , [Ru IV (O)] 2+ and [Ru III (H 2 O)] 3+ , respectively.…”

“…Such destabilizing orbitals effect can happen, for example, when the FMOs dipole moments do not have the same direction as the molecular dipole moment, thus inducing a destabilizing effect. 89 Conversely, the H(or S)OMO and LUMO orbitals stability are also connected to the total charges of the Ru-complex species. In solution, the H(or S)OMO (and LUMO) energies are À5.02 (À2.…”

“…91 According to the definitions given by Parr and Pearson [92][93][94] and the Koopmans theorem, m = (e L + e H )/ 2 and Z = (e L À e H )/2, where e L and e H are the energy of LUMO and HOMO respectively. 89 For [Ru II (H 2 O)] 2+ (and [Ru II (OH)] + ), m is worth À9.70 (À6.15) and À4.42 (À3.73) eV in vacuum and in solution, respectively. It means that the solvation or the abstraction of a proton makes the chemical potential less negative, facilitating the removal of electrons from the complexes, thus making easier any chemical process.…”

An ab initio and TD-DFT study of solvent effect contributions to the electronic spectrum of Nile Red

“…The HOMO orbital energy is unaffected and the HOMO-1 orbital is only very slightly stabilized. This variability in orbital energy stabilization is not uncommon [34][35][36] and only recently has a systematic understanding of the effects been considered. 37 The red shift in the S 0 -S 1 transition can be rationalized as a result of the LUMO orbital energy being stabilized preferentially by the more polar solvent field.…”

A systematic understanding of orbital energy shift in polar solvent

“…In fact, it is also well known that computed in solution phase is different from that in gas phase due to the interaction between solute and solvent. [4][5][6][7] The electronic structure of solvated molecule can be calculated using solvation theory such as the family of reference interaction site modelself-consistent field [8][9][10] ͑RISM-SCF͒ and polarizable continuum model ͑PCM͒. 11 However, the obtained shifts look often random; sometimes increases and sometimes decreases.…”