Volatile Organic Compound Colorimetric Array Based on Zinc Porphyrin and Metalloporphyrin Derivatives

Organic thin films based on ZnTPP and two metalloporphyrin derivatives, i.e. (2-Nitro-5, 10, 15, 20-tetraphenylporphyrinato) zinc (II) (ZnTPP-NO2) and (2, 3-Dioxo-5, 10, 15, 20-tetraphenylporphyrinato) zinc (II) (ZnTPP=O) have been deposited by spin-coating and used as optical chemically interesting materials for the detection of pyridine, ethyl acetate and methanol vapors. In particular, very interesting results have been obtained by optical absorption measurements carried out in the specific region and the selectivity towards different vapor analytes, depending both on the metal ion and the peripheral substituent of the macrocycle, was found. Moreover, this paper reports the use of an idea to analyze the variation in the area integral corresponding to the typical absorption peaks in defined spectral range for each sensing layer. The three sensing materials have been arranged in a colorimetric array configuration and examples of applications for “electronic nose”, and shown good responses to single analyte.