Metal ion sensing functional mono and double-decker lanthanide phthalocyanines: Synthesis, characterization and electrical properties

We report, in this study, the preparation, physical characterization metal ion sensing properties of peripherally functionalized ionophore ligand, 4,5-bis(6-hydroxyhexylthio)-1,2-dicyanobenzene (1) and its mono 2,3,7,8,12,13,17,18-octakis(6-hydroxyhexylthio)phthalocyaninatometal (II) {M = Zn^II (2), Cu^II (3)} and double-decker lanthanide bis-phthalocyanines, {([4,5,4′,5′ 4″,5″,4‴,5‴]-tetrakis-(6-hydroxyhexylthio)phth alocyaninatolanthanium(III)}){M[Pc(S-C₆H₁₃OH) ₄]₂} {M = Eu^III (4), Yb^III (5), and Lu^III (6)}. All benzenes on phthalocyanines are functionalized with hydroxyhexylsulfanyl moieties for potential use as soft metal ion binding, such as Ag⁺ and Pd²⁺. The temperature dependence of the dc and ac conduction properties of 4, 5 and 6 thin films have been investigated in the frequency range of 40-10⁵ Hz and temperature range 290-436 K. The dc results showed an activated conductivity dependence on temperature for all films. Obtained data reveal that ac conductivity obeys the relation σ_ac(ω) = Aω^s and exponent is found to decrease by increasing temperature. The data obtained results were compared with the prediction of the Quantum Mechanical Tunelling (QMT) and Correlated Barrier Hopping (CBH) models. The analysis showed that the CBH model is the dominant conduction mechanism for the electron transport in the films. The new synthesized compounds have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, MS, UV-vis and EPR spectral data.