Vicente Parra

Electrical transduction in phthalocyanine-based gas sensors: from classical chemiresistors to new functional structures

Phthalocyanines are organic-based materials which have attracted a lot of research in recent times. In the field of sensors, they present interesting and valuable potentialities as sensing elements for real gas sensor applications. In the present article, and taking some of our experiments as representative examples, we review the different ways of transduction applied to such applications. Some of the new tendencies and transducers for gas sensing based on phthalocyanine derivatives are also reported. Among them, electrical transduction (resistors, field-effect transistors, diodes, etc.) has been, historically, the most commonly exploited way for the detection and/or quantification of gas pollutants, vapors and aromas, according to the conducting behavior of phthalocyanines. We will focus precisely on these systems.

Grafting of Porphyrins on Cellulose Nanometric Films

Ultrathin films of cellulose were functionalized with iron protoporphyrin IX (FePP). Spin-coating allows the production of silylated cellulose films in a controlled way. Cellulose regeneration is achieved through the hydrolyzation of the silane groups, exposing the film to acidic vapors. To enhance the reactivity of the cellulose surface to the protoporphyrin, carbonyldiimidazole (CDI) was used as an activator. The effect of different spacers on the porphyrin grafting such as 1,8-diaminooctane and 1,4-phenylenediamine was studied. The highest level of cellulose functionalization with FePP was achieved when both the cellulose film and FePP were activated by CDI and a diaminoalkane was used as a spacer between the surface and the FePP. ATR/MIR (attenuated total reflection in multiple internal reflections) was performed in situ to follow the kinetics of the different chemical reactions with the cellulose surface. ATR/MIR proved again to be a powerful tool for probing the surface reaction. X-ray photoelectron spectroscopy permitted the elemental analysis of the cellulose surface after the chemical modification.