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It is known that among other applications porphyrin aggregates can be used in the detection of volatile organic compounds (VOC) and gases and vapors in general. However, the use of porphyrins for this purpose has been limited by the fact that usually the porphyrin and the polymer employed as a matrix are soluble in different media, such as polyvinyl alcohol and tetraphenylporphyrin, respectively. In this paper, we discuss how starting from stable aqueous solutions of hydrophobic porphyrins one can use the drop coating method to prepare polyvinyl alcohol polymer matrices containing porphyrin aggregates. The resulting solid films were characterized by optical techniques, and we have used UV-vis absorption spectroscopy to analyze how they interact with vapors of HCl , NO2 and NH3 .

Porphyrin nanoaggregates formed in the interior of colloidal suspensions can be considered as examples of supramolecular systems with self-organized architecture. Due to their peculiar optical and electrochemical properties such as decrease of fluorescence, increase of conductivity and possible electron transfer, these aggregates can be used in the design and fabrication of optoelectronic devices, such as organic solar cells and optical and electrochemical sensors. In this paper, we first describe the synthesis of a series of hydrophobic tetraphenylporphyrins by a change in the order of reagents addition that results in high yields of the desired products. These products were then employed to obtain stable suspensions of porphyrinic nanoaggregates in aqueous solutions of sodium dodecyl sulfate (SDS). The aggregates resulting of the encapsulation of the tetraphenylporphyrins into the micelles of the surfactant were studied by dynamic light scattering (DLS), atomic force microscopy (AFM) and UV-vis and fluorescence spectroscopies. The results indicate that the nanoggregates have a spherical morphology with particles whose average size ranges between 46–78 nm and ζ-potential values (higher than 55 mV), indicative of excellent stability. Optical characterization was used to determine the classification of nanoaggregates, according to the observed shifts on the absorption spectra.

A series of triphenylamino (TPA)-chalcones and triphenylamino-β-arylchalcones, displaying either D-π-D or D-π-A architecture, were synthesized through aldol condensations and Heck reactions. The chalcone derivatives display intense absorption bands ranging from 389 to 432 nm and molar extinction coefficients of ca. 10 5 L mol-1 cm-1 corresponding to π-π* electronic transitions. The photoluminescence emissions are peaked between 470 and 563 nm with large Stokes shifts (80-131 nm), attributed to charge transfer in the excited state. The dyes present low fluorescence quantum yields, which is attributed to radiationless excited state deactivation related to aryl rings rotation. Spectroscopic and electrochemical methods were used to determine the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. Both optical and electrochemical properties of the TPA-chalcone derivatives are considerably affected by the substitution pattern of the chalcones aryl rings and also by the β-arylation of the olefin moiety.