Synthesis, fabrication of self-assembled film and ambipolar chemical sensing properties of triple-decker (phthalocyaninato) (porphyrinato) europium complex

摘要

A mixed (phthalocyaninato) (porphyrinato) europium triple-decker complex, named (TPyP)Eu-2[Pc(OC4H9)(8)](2) [TPyP = dianion of 5,10,15,20-tetra(4-tert-pyridyl) porphyrin, Pc(OC4H9) (8) = 2,3,9,10,16,17,23,24-octabutoxyphthalocyaninate] is synthesized and characterized by MALDI-TOF, 1HNMR, UV-visible spectra and differential pulse voltammetry techniques. Introduction of electron-donating butoxy groups at the periphery of the phthalocyanine ligands and electron-withdrawing pyridyl substituents onto the meso-positions of the porphyrin ring not only increases the solubility of the triple decker but successfully tunes the HOMO and LUMO energy levels into a soluble ambipolar organic semiconductor. A simple quasi-Langmuir-Shafer (QLS) method is used to fabricate self-assembled film of (TPyP)Eu-2[Pc(OC4H9)(8)](2). Excellent sensitivity, reproducible n-type and p-type responses to electron-accepting gas NO2 and electron-donating gas NH3 are found for the films of (TPyP)Eu-2[Pc(OC4H9)(8)](2) complex at room temperature. The detection limit towards NO2 and NH3 is as low as 0.4 ppm and 1 ppm, respectively, with percentage current change of 4.2% and 1.6%, depending on the uniform molecular packing and intermolecular interactions among the triple decker molecules. The present results represent not only the excellent example of ambipolar triple-decker phthalocyanine-based sensors obtained by a solution-based method, but more importantly provide a new strategy for the molecular design to obtain soluble ambipolar organic semiconductors in sensing device fabrication.