RESUMO
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 0.11-0.20eV. The very low lasing efficiency (7.8-8.4%) of 4PhDPM compound was explained by the T1âT4 and T1âT5 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.
Assuntos
Elétrons , Luz , Porfobilinogênio/análogos & derivados , Teoria Quântica , Simulação por Computador , Modelos Moleculares , Estrutura Molecular , Fotoquímica , Porfobilinogênio/química , Espectrometria de FluorescênciaRESUMO
In the framework of density functional theory the equilibrium geometry of the ground electronic state of monoamine tetraphenylporphyrin with the complexon of ethylenediaminetetraacetic acid was found using B3LYP functional and 6-31G(d,p) basis set. Electronic absorption spectrum of this molecule in ethanol solution was measured in the range of 300-600nm and interpreted using the PCM/TDDFT method (with the B3LYP, CAMB3LYP, M06-2X functionals) with 6-31G(d,p) and 6-31++G(d,p) basis sets. The observed and calculated line positions and intensities are well agreed.
Assuntos
Ácido Edético/química , Porfirinas/química , Elétrons , Modelos Moleculares , Teoria Quântica , Espectrofotometria UltravioletaRESUMO
The association of a ratio of blood porphyrin fraction concentrations in pregnant women with hyperandrogenism (HA) with the osmoresistance of red blood cells and the microviscosity of their membranes was studied. A cohort examination was made in parallel groups of 64 pregnant women aged 20 to 30 years at 28-36 weeks gestation. The levels of dehydroepiandrosterone sulfate (DHEAS) and testosterone were measured. External cardiotocography, ultrasonography, and Doppler study were conducted. The blood concentrations of endogenous protoporphyrin (PP) and coproporphyrin (CP) were estimated by the spectral fluorescence technique. Erythrocytic membrane microviscosity was determined from the degree of pyrene eximeration, by measuring the fluorescence spectra; erythrocytic osmoresistance was ascertained by the procedure developed by N. L. Vasilevskaya. The pregnant women with placental insufficiency in the presence of HA were found to have an altered ratio of the concentrations of erythrocytic porphyrin fractions, which enhanced the microviscosity and resistance of red blood cell membranes, causing worse microcirculation. There was an inverse correlation between the level of DHEAS and the ratio of the concentrations of endogenous PP to CP. It is concluded that the development of placental insufficiency in pregnant women with HA is attended by the decreased ratio of PP to CP along with the higher microviscous characteristics of erythrocytic membranes and the lower amplitude of their osmoresistance, by increasing the lower osmoresistance range.