Abstract This paper evaluated the influence of the incorporation of the coinitiator Ethyl 4-(dimethylamino) benzoate (EDB) in Filtek Z250 XT resin in the reduction of the polymerization time and its behavior in halogen light and LED (Light Emitting Diode) light. The samples were subjected to thermal and spectroscopic analysis. The TG/DTG-DTA curve showed that both samples studied have a thermal stability temperature similar to the other polymers in the monomer blend. Morphological features were analyzed by SEM. By the MIR analysis, the degree of conversion using halogen light showed a better result compared to the LED light. The polymerization time applied to the specimens was 10 seconds, reducing the original resin time by half.

Abstract 1,4-dihydro-1,2,4,5-tetraarylpyrrolo[3,2-b]pyrroles are a versatile class of materials with simple synthesis and promising application in organic electronic devices. In this work we present a method of synthesis of new 1,4-dihydro-1,2,4,5-tetraarylpyrrolo[3,2-b]pyrrole derivatives, with ester and carboxylic acid groups as anchoring groups, by multicomponent reactions using niobium pentachloride as catalyst. The new materials were structurally and optically characterized. Also, it was compared the bonding of different moieties to the titanium dioxide mesoporous film. The preliminary tests as dyes in standard configuration in dye-sensitized solar cells have shown a potential performance in the energy conversion.

Multicomponent reactions between phenols, β-diesters and benzaldehydes for the synthesis of 4-aryl-3,4-dihydrocoumarin derivatives were carried out under mild conditions (room temperature) and presented moderate yields (38-88%) and reasonable reaction times (2-4 days), using niobium pentachloride as a catalyst.

The intramolecular Friedel-Crafts acylation reaction of 3-arylpropanoic acids to give 1-indanones can be effected in good yields under mild conditions (room temperature) by using niobium pentachloride. Our results indicate that NbCl5 acts both as reagent (to transform carboxylic acids into acyl chlorides) and as catalyst in the Friedel-Crafts cyclization.