Designing new quinoline-based organic photosensitizers for dye-sensitized solar cells (DSSC): a theoretical investigation.

In this work, 27 new quinoline-derivative dyes were proposed, and their geometries, electronic structures, and absorption spectra were investigated using density functional theory (DFT) calculations. An important feature found in most of the new compounds was that the lowest unoccupied molecular orbital (LUMO) was above the TiO2 conduction band, facilitating electron transfer from the excited dye to the semiconductor. The energy of the highest occupied molecular orbital (HOMO) was below the reduction potential energy of the electrolyte (I-/I3-), improving the charge regeneration process after photooxidation. Here we present compounds with a small band gap, favorable absorption properties, a D-π-A-type structure that exhibits maximum absorption above 540 nm, and a high light harvesting efficiency (LHE > 0.78). The results show that the compounds D1C, D2C, D3C, and R3C could be used as dye sensitizers for dye-sensitized solar cells (DSSCs).

Excited state absorption spectra of dissolved and aggregated distyrylbenzene: A TD-DFT state and vibronic analysis.

A time-dependent density functional theory study is performed to reveal the excited state absorption (ESA) features of distyrylbenzene (DSB), a prototype π-conjugated organic oligomer. Starting with a didactic insight to ESA based on simple molecular orbital and configuration considerations, the performance of various density functional theory functionals is tested to reveal the full vibronic ESA features of DSB at short and long probe delay times.

Theoretical-Experimental Photophysical Investigations of the Solvent Effect on the Properties of Green- and Blue-Light-Emitting Quinoline Derivatives.

This paper describes the investigations on the solvatochromic effect and the photophysical properties of quinoline derivatives, compounds with potential applicability in optoelectronic devices. Using an experimental and theoretical approach, the effect of the solvent and the insertion of the phenyl, nitro, amino and dimethylamino group in the quinoline backbone were investigated. The use of Density Functional Theory (DFT) calculations provided the bases for the understanding of the energetic transitions observed in the absorption and fluorescence experiments. In general, it was observed a change in the wavelength of maximum absorption and fluorescence quantum yield of the studied compounds caused by the substituents in the quinoline core. This effect was correlated with the solvent dielectric constants.

Febrifugine derivative antimalarial activity: quantum mechanical predictors.

Plasmodium falciparum resistant strain development has encouraged the search for new antimalarial drugs. Febrifugine is a natural substance with high activity against P. falciparum presenting strong emetic property and liver toxicity, which prevent it from being used as a clinical drug. The search for analogues that could have a better clinical performance is a current topic. We aim to investigate the theoretical electronic structure by means of febrifugine derivative family semi-empirical molecular orbital calculations, seeking the electronic indexes that could help the design of new efficient derivatives. The theoretical results show there is a clustering in well-defined ranges of several electronic indexes of the most selective molecules. The model proposed for achieving high selectivity was tested with success.

Febrifugine derivative antimalarial activity: quantum mechanical predictors / Descritores da atividade antimalarial de derivados de febrifugina obtidos via mecânica qüântica

Plasmodium falciparum resistant strain development has encouraged the search for new antimalarial drugs. Febrifugine is a natural substance with high activity against P. falciparum presenting strong emetic property and liver toxicity, which prevent it from being used as a clinical drug. The search for analogues that could have a better clinical performance is a current topic. We aim to investigate the theoretical electronic structure by means of febrifugine derivative family semi-empirical molecular orbital calculations, seeking the electronic indexes that could help the design of new efficient derivatives. The theoretical results show there is a clustering in well-defined ranges of several electronic indexes of the most selective molecules. The model proposed for achieving high selectivity was tested with success.

O desenvolvimento de linhagens resistentes de Plasmodium falciparum tem encorajado a busca por novas drogas antimalariais. A febrifugina é uma substância natural com alta atividade contra o P. falciparum que apresenta propriedade emética e toxicidade para o fígado tal que não permitem o seu uso clínico. A busca por análogos que possam ter uma performance clínica melhor é um tema de pesquisa atual. Nosso objetivo é investigar a estrutura eletrônica teórica de uma família de derivados da febrifugina empregando cálculos semi-empíricos de orbitais moleculares, procurando por índices eletrônicos que possam ajudar a modelar novos derivados mais eficientes. Os resultados teóricos mostram que para as moléculas mais seletivas existe um agrupamento dos valores de determinados índices em intervalos bem definidos. O modelo proposto para se obter alta seletividade foi testado com sucesso.