Gas Sensing With Zinc Phthalocyanine‐Functionalized Quartz Crystal Microbalances

ABSTRACT Phthalocyanines have long been employed as highly effective sensing molecules in various chemical sensors—including quartz crystal microbalance (QCM), surface acoustic wave, and conductivity‐based devices—owing to their strong sensing capabilities and broad sorption characteristics. The sensing performance of these compounds is largely governed by the type of central metal ion and the nature of the substituent groups attached to the periphery of the macrocyclic ring. In this study, two new zinc phthalocyanine (ZnPc) derivatives bearing different peripheral substituents were synthesized and applied as active coating materials in QCM gas sensors. Both compounds exhibited stable, reversible, and concentration‐dependent frequency responses toward various volatile organic compounds (VOCs) and the nerve agent simulant dimethyl methylphosphonate (DMMP). Differences in substituent groups significantly influenced adsorption behavior and sensor selectivity. The fluorinated and sulfanyl‐substituted ZnPc ( 1a ) showed the highest sensitivity toward DMMP (∼60 Hz ppm − 1 , Δ f ≈ 1000 Hz), whereas the ethylthio‐substituted ZnPc ( 1b ) produced stronger responses toward aromatic VOCs such as chlorobenzene and o‐xylene. The results demonstrate that small structural modifications in ZnPc derivatives can effectively alter sensor performance and selectivity. Through this approach, the development of QCM‐based sensors for both chemical warfare agent (CWA) threat detection and industrial VOC monitoring becomes feasible.