Chromone derivatives exhibiting high absorbance values in the UVA/UVB region were synthesized, and their photoprotective properties were evaluated. Chromones were prepared according to known literature procedures and characterized by high resolution mass spectrometry, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. The in vitro solar protection factor (SPF) was determined by the Mansur method and cytotoxicity was evaluated using the sulforhodamine B assay. Two of the chromones synthesized demonstrated suitable SPF values and displayed no cytotoxic effect towards MRC-5 human fibroblasts at the tested concentrations, indicating great potential for future in vivo assays and clinical trials. Finally, the lead compound was incorporated into a nanoemulsion. Nanoemulsions showed high droplet size homogeneity and excellent stability. Chromones bearing methoxy substituents were found to be the most promising compounds with ideal photoprotective properties desirable for utilization and incorporation in sunscreen formulations.

Five new π-conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the target compounds was performed by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), 13C NMR, thermogravimetric analysis (TGA), absorption and emission spectroscopy techniques. Arylcinnamic acids were obtained as pure E-isomers. On the other hand, arylacrylonitrile was obtained as a mixture of E/Z-isomers and the pure E-isomer was isolated in chromatographic columns. The liquid crystal properties were investigated through differential scanning calorimetry and polarized optical microscopy. All chromophores displayed smectic and nematic mesophases. These materials displayed intense fluorescence under UV-Vis light excitation. The maximum absorption peaks were observed between 342-356 nm while emission varied from 428 to 460 nm in chloroform solution. Higher values for the quantum fluorescence yield were associated with acrylic acids compared to arylacrylonitriles. The solvatochromism studies of the materials showed a significant increase in the red-shift of the fluorescence spectra as the polarity of the solvent increased. In some cases, a variation in the emission wavelength from the blue to the green region of the spectrum was observed.

ABSTRACT The excessive sun exposure, coupled with lack of sun protection represents one of the biggest risks to the occurrence of skin cancer and photoaging. Recent strategies for photoprotection have included the incorporation of natural antioxidant and anti-inflammatory compounds, into sunscreens, and the oral administration of natural antioxidant extracts. In this work, we use Brazilian red propolis extract because its antioxidant and anti-inflammatory activities. The aim of this work was to evaluate the sun protection factor and antioxidant activity of different hydroalcoholic extracts of red propolis (70% and 75%) prepared from lyophilized red propolis at room and high temperatures. The sun protection factor in vitro was determined by a spectrophotometric method developed by Mansur. The hydroalcoholic extracts of red propolis incorporated with Filter UVA-UVB 5% Gel Permulem TR-1 presented absorption in the UVB region. Also, the in vitro capacity of the hydroalcoholic extracts of red propolis to increase photoprotective activity of Filter UVA-UVB 5% Gel was evaluated. The hydroalcoholic extracts of red propolis incorporated presented higher values of sun protection factor and showed synergism in the photoprotective activity of Filter UVA-UVB 5% Gel Permulem TR-1. The antioxidant activity and sun protection factor are correlated with total phenolics content of the extracts and the hydroalcoholic extract of red propolis 75% at room temperature was choosen. The formulation developed with Filter UVA-UVB 5% Gel Permulem TR-1 with this hydroalcoholic extract of red propolis showed safe to be applied on the skin according HET-CAM test. Suggests indication of hydroalcoholic extract of red propolis (75% – room temperature) associated to photoprotective formulations for use in photoprotective products.

Although Quercetin absorbs in the UVA/UVB electromagnetic region, it is limited for applications as a UV filter due to its low lipophilicity and capacity to penetrate the epidermis. In order to overcome this limitation, we synthetized and evaluated the photo protective properties of a derivative obtained from Quercetin. The derivative was prepared by alkylation of Quercetin with iodoethane and characterized by IR and NMR spectroscopy. The in vitro Solar Protection Factor was determined by the Mansur method and the cytotoxicity was evaluated using hepatocellular cell (Hep G2) cells. Finally, Quercetin and the corresponding derivative were incorporated in nanoemulsions. Nanoemulsions with particles sizes between 53 and 73 nm were obtained, and polydispersity indexes were around 0.1, indicating good homogeneity of the nanoemulsion particles. The cell viability study for the Quercetin derivative indicated a very low cytotoxicity profile. The chemical modification of Quercetin resulted in a promising compound with improved properties desirable for skin penetration and incorporation into sunscreen formulations.

Neste trabalho, filmes de polianilina (PAni) depositados por eletropolimerização potenciostática pulsada foram utilizados como camada transportadora em dispositivo orgânico fotovoltaico de heterojunção. Os filmes de PAni foram depositados sobre eletrodo de óxido de índio e estanho (ITO) utilizando-se potenciais pulsados de 1,0 V e 1,5 V em solução ácida contendo 0,1 M de monômero anilina. Os filmes apresentaram coloração esverdeada, uniforme e sem descontinuidades. A morfologia dos filmes de PAni foi analisada por imagens de microscópio de força atômica (AFM) e sua estabilidade foi verificada através de curvas de voltametria cíclica. Análise de espectroscopia de absorção ultravioleta-visível (UV-Vis) evidenciou a obtenção de filmes poliméricos no estado condutor (base esmeraldina). Os filmes de PAni depositada por eletropolimerização potenciostática pulsada sob diferentes tensões foram utilizados como camada transportadora de cargas em dispositivos fotovoltaicos de heterojunção à base de polímeros conjugados. As eficiências de conversão de energia (η) dos dispositivos com estrutura ITO/PAni/MDMO-PPV_PCBM/Al foram determinadas através da curva densidade de corrente-tensão (J-V) e comparadas com os dispositivos construídos sem a camada de PAni com estrutura ITO/MDMO-PPV_PCBM/Al, e observou-se que os dispositivos contendo filmes de PAni apresentaram eficiência cerca de 4 vezes maior.

Polyaniline (PAni) films obtained by means of pulsed potentiostatic electropolymerization were used as hole-transporting layer in organic photovoltaic devices. PAni films were deposited onto Indium Tin Oxide (ITO) from an acid solution containing 0.1 M aniline monomer at pulsed potentials of 1 V and 1.5V. The PAni films were characterized by Atomic Force Microscopy (AFM), Cyclic voltammetry and UV-Vis absorption spectroscopy. The active layer of poly[2-methoxy-5-(3’,7’-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and phenyl-C61-butyric acid methyl ester (PCBM) was spin coated onto PAni films to obtain the ITO/PAni/MDMO-PPV_PCBM/Al photovoltaic device structures. The power conversion efficiency (η) of multilayered devices was evaluated by current density-voltage (J-V) curves. The results indicate that devices obtained with PAni films exhibit a 4-fold increase in conversion efficiency compared to devices without PAni films.

In this work we investigated the effect of visible radiation on the electrical properties of poly[(2-methoxy-5-hexyloxy)-p-phenylenevinylene]- MH-PPV films and light emitting diodes. Complex impedance measurements of (Au or ITO)/MH-PPV/(Au or Al) samples were carried out at room temperature and exposed to white light. Over the frequency range from 100 mHz to 2 MHz, the electrical results of Au/MH-PPV/Au was dominated by the Cole-Cole approach, where the electrode influence is negligible. However, some additional influence of the interface was observed to occur when Al was used as electrode. These effects were observed under both dark and visible-light illumination conditions. A simple model based on resistor-capacitor parallel circuits was developed to represent the complex impedance of the samples, thereby separating bulk and interface contributions. We observed that the polymer electrical resistivity decreased while the dielectric constant of the polymer and the thickness of the Al/MH-PPV layer were almost constant with increasing light intensity. The decrease of the polymer layer resistance comes from a better charge injection due to a light induced dissociation of positive charge carriers at the electrode.