Synthesis, characterization, electrochemistry and VOC sensing properties of novel ball-type dinuclear metallophthalocyanines

Abstract

Abstract New homodinuclear ball-type Cu(II)–Cu(II) 4 , Zn(II)–Zn(II) 5 , and Co(II)–Co(II) 6 phthalocyanines were synthesized from 4,4′-(9H-fluorene-9-yl-dimethoxy)diphthalonitrile 3 , which was obtained by the reaction of 4-nitrophthalonitrile 2 with 9H-fluorene-9,9-dimethanol 1 . The compounds were characterized by elemental analysis, UV/vis, IR, 1 H NMR, 13 C NMR and MALDI-TOF mass spectroscopies. Electrochemical and spectroelectrochemical measurements suggested that ball-type phthalocyanine compounds 4–6 form stable mixed-valence species in nonaqueous medium, as a result of the remarkable intramolecular interactions between the two metallophthalocyanine units. Ball-type cobalt phthalocyanine complex, 6 showed high catalytic activity toward dioxygen reduction. Temperature dependence of direct current (dc) conductivity of the films of 4–6 in the range of 295–523 K displayed their semiconductor behavior. Alternating current (ac) conductivity measurements (40 Hz–100 kHz) showed that dominant conduction mechanism for 4–6 can be modeled depending on temperature and frequency. Gas sensing properties of the thin films of 4–6 toward volatile organic compounds (toluene, chloroform, and acetone) at room temperature were good with reversible response. The best sensitivities were obtained with the film of 6 for the vapors of toluene (250 ppm), acetone (150 ppm), and chloroform (1500 ppm) with the values of 1.3 × 10 −1 , 1.6 × 10 −2 , and 2.1 × 10 −2 ppm −1 , respectively.