Valiev R.R.,Tomsk Polytechnic University |
Sinelnikov A.N.,Tomsk State University |
Aksenova Y.V.,Tomsk State University |
Kuznetsova R.T.,Tomsk State University |
And 3 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2014
The electronic excited states of BF2 dipyrromethene (2BrDPM, DPMI, DPMII, PM567 and 4PhDPM) complexes were investigated using the extended multi-configuration quasi-degenerate at the second order of perturbation theory (XMCQDPT2) and the second-order approximate coupled-cluster (CC2) methods. The excitation energies calculated by CC2 are significantly overestimated by 0.42-0.59 eV because of the substantial contributions of double excitation levels to excited states (>10%). However, the calculated XMCQDPT2 excitation energies agree well with experimental ones within the accuracy 0.11-0.20 eV. The very low lasing efficiency (7.8-8.4%) of 4PhDPM compound was explained by the T1 → T4 and T1 → T5 reabsorptions at XMCQDPT2 level of theory. The molecular photonics of pyrromethenes are studied using a combination of the first-principle and semi-empirical calculations. The main mechanism for the deactivation of the energy of the first singlet excited electronic state is the radiative electronic transition for DPMI, DPMII, PM567 and 4PhDPM compounds. Also, the main mechanism for the quenching of fluorescence in considered complexes (except DPMII compound) is the internal conversion. The processes of the internal conversion and intersystem crossing compete with each other in DPMII compound. The measured and calculated fluorescence quantum yields agree well for all considered molecules. © 2013 Elsevier B.V. All rights reserved.
Mikhalitsyna E.A.,Russian Academy of Sciences |
Tyurin V.S.,Russian Academy of Sciences |
Nefedov S.E.,Russian Academy of Sciences |
Syrbu S.A.,ISCTU |
And 3 more authors.
European Journal of Inorganic Chemistry | Year: 2012
New 5-(4-bromophenyl)-3,7,12,13,17,18-hexamethyl-2,8-dipentyl- and 5,15-bis(4-bromophenyl)-2,8,12,18-tetramethyl-2,8,12,18-tetrapentylporphyrins (H2P-1 and H2P-2) and their zinc metal complexes (ZnP-1 and ZnP-2, respectively) were synthesized in high yields by condensation of β-tetraalkyl-substituted dipyrromethanes with 2-formyl-3,4-dialkylpyrroles or 4-bromobenzaldehyde and subsequent metallation. X-ray analysis data showed the formation of axial complexes of ZnP-1 and ZnP-2 with the solvent molecules of THF and dioxane in the solid state. Coordination of ZnP-1 with dioxane led to polymer multidecker structures. Axial coordination of oxygen-containing solvent molecules leads to supramolecular self-organization of zinc porphyrins into multidecker cofacial structures. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.