RESUMO
By means of density functional theory, we have studied the electronic structure and vibronic properties of single neutral NiPc, PdPc, and PtPc molecules and their singly and doubly ionized cations and anions. In particular, the vibronic couplings and reorganization energies of all systems are compared. Partitioning of the reorganization energy, corresponding to the photoelectron spectra of the first and second ionizations of studied molecules, into normal mode contributions shows that the major contributions are due to several vibrational modes with a(1g) symmetry and energies lower than 1600 cm(-1). The results reveal that the reorganization energy due to the singly positive ionization in the studied molecules is up to about one order of magnitude less than other reorganization energies. This makes these metal phthalocyanines, from the perspective of intramolecular reorganization energies, attractive as electron donor for intramolecular electron transfer in electron acceptor-donor systems.
RESUMO
The S(1)((1)A('))<--S(0)((1)A(')) absorption spectrum of jet-cooled 2,3-benzofluorene (Bzf) has been measured by cavity ring-down spectroscopy. The potential energy surfaces of the S(n=0,1,2) states of Bzf have been investigated with calculations based on the time-dependent density functional theory (TD-DFT). At the B3LYP/TZ level of theory, TD-DFT does not deliver a realistic difference between the excited S(1) and S(2) potential energy surfaces, a problem which can be avoided by introducing a reference geometry where this difference coincides with the observation. In this geometry, an expression for the Herzberg-Teller corrected intensities of the vibronic bands is proposed, allowing a straightforward assignment of the observed a(') modes below 900 cm(-1), including realistic calculated intensities. For vibronic bands at higher energies, the agreement between calculated and observed modes is deteriorated by substantial Dushinsky rotations and nonparabolicities of the potential energy surface S(1).