BackgroundImidazo[1,2-a]pyridines and pyrimidines are important organic fluorophores which have been investigated as biomarkers and photochemical sensors. The effect on the luminescent property by substituents in the heterocycle and phenyl rings, have been studied as well. In this investigation, series of 3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines were synthesized and evaluated in relation to fluorescence emission, based upon the hypothesis that the hydroxymethyl group may act as an enhancer of fluorescence intensity.ResultsCompounds of both series emitted light in organic solvents dilutions as well as in acidic and alkaline media. Quantitative fluorescence spectroscopy determined that both fused heterocycles fluoresced more intensely than the parent unsubstituted imidazo[1,2-a]azine fluorophore. In particular, 3-hydroxymethyl imidazo[1,2-a]pyridines fluoresced more intensely than 3-hydroxymethyl imidazo[1,2-a]pyrimidines, the latter emitting blue light at longer wavelengths, whereas the former emitted purple light.ConclusionIt was concluded that in most cases the hydroxymethyl moiety did act as an enhancer of the fluorescence intensity, however, a comparison made with the fluorescence emitted by 2-aryl imidazo[1,2-a]azines revealed that in some cases the hydroxymethyl substituent decreased the fluorescence intensity.

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One of the main uses of energy is the heating of fluids, mainly water and air. In the residential and industrial sectors, energy applications are diverse, mainly; Prepared food, washing clothes and personal hygiene, as well as the generation of steam and heat to process. The solar collectors represented an excellent sustainable alternative to cover the needs of these sectors. In Mexico there is a diverse market of brands and solar equipment, mostly of foreign origin. But those manufactured in our country. With selective coatings, such as titanium oxide, they are imported, and the substances and processes used are highly toxic and harmful to the environment. Given this, selective organic coatings represent an excellent alternative. It is important to increase the thermal efficiency of the solar collectors, as well as to improve the heat transfer in a thermal tank. For all the above, this research proposes a solar collector for 15 liters of water with organic selective coating and the support of a heat exchanger with nano fluid. So far, the best results are: thermal efficiency of 0.58 with a 0.1% concentration of ZnO nano fluid, thermal efficiency of 0.6 with a concentration of 0.1% ZnCuO nano fluid and thermal efficiency of 0.63 with a concentration of 0.1% CuO nano fluid.   Uma das principais utilizações da energia é o aquecimento de fluidos, principalmente água e ar. Nos sectores residencial e industrial, as aplicações energéticas são diversas, principalmente; alimentos preparados, lavagem de roupa e higiene pessoal, bem como a geração de vapor e calor para processar. Os colectores solares representaram uma excelente alternativa sustentável para cobrir as necessidades destes sectores. No México existe um mercado diversificado de marcas e equipamentos solares, na sua maioria de origem estrangeira. Mas aqueles fabricados no nosso país. Com revestimentos selectivos, tais como óxido de titânio, são importados, e as substâncias e processos utilizados são altamente tóxicos e prejudiciais para o ambiente. Por isso, os revestimentos orgânicos selectivos representam uma excelente alternativa. É importante aumentar a eficiência térmica dos colectores solares, bem como melhorar a transferência de calor num tanque térmico. Por tudo isto, esta investigação propõe um colector solar para 15 litros de água com revestimento orgânico selectivo e o apoio de um permutador de calor com nanofluido. Até agora, os melhores resultados são: eficiência térmica de 0,58 com uma concentração de 0,1% de ZnO nano fluido, eficiência térmica de 0,6 com uma concentração de 0,1% de ZnCuO nano fluido e eficiência térmica de 0,63 com uma concentração de 0,1% de CuO nano fluido.