QCM sensors functionalized with non-peripheral 5,6,7,8-tetrahydronaphthalen-2-oxy substituted Phthalocyanines for the detection of metal ions in water samples

Non-peripheral 5,6,7,8-tetrahydronaphthalen-2-oxy substituted metallo (CuPc, CoPc, Mn( OAc )Pc) and metal-free (2HPc) phthalocyanines were designed and synthesized for the detection of Metal Ions (MIs) using a flow-type Quartz Crystal Microbalance (QCM) technique. These novel compounds were synthesized using 3-(5,6,7,8-tetrahydronaphthalen-2-oxy)phthalonitrile and appropriate metal salts and characterized by FT-IR, UV– Vis , ¹H NMR, ¹³C NMR, and MALDI-TOF mass spectral data. The effects of metals on spectroscopic properties and aggregation behaviors of the novel phthalocyanines were investigated in different solvents. J -aggregated species were observed in CoPc in the acidic solvents (CH₂Cl₂ and CHCl₃). Acid-induced J -aggregation was confirmed by the destruction of aggregation with the addition of Na₂CO₃ to the medium. The MI sensing performance of these compounds toward Mg²⁺, Ni²⁺, and Co²⁺ ions, which are selected as representative of hard, soft, and borderline Lewis acids, respectively, was studied experimentally. The results showed that these novel compounds have great potential to detect these metal ions in water within the permissible limits.