Oxidative polymerization of terthiophene and a substituted thiophene monomer in metal-organic framework thin films. (December 2018) - Haldar, Ritesh
Graphical abstract: The oxidative polymerization of terthiophene and a substituted thiophene has been successfully carried out inside the pores of surface anchored metal-organic frameworks (SURMOFs). Using SURMOF-2 thin film as a porous host, terthiophene and 3, 4-ethylenedioxythiophene monomers are oligomerized into oligomers. The ease of deposition of these oligomer:MOF composite thin films on transparent, conductive substrates offers possibilities for future optolelectronic applications. Highlights: Terthiophene and 3, 4-Ethylenedioxythiophene have been encapsulated inside the 1D pores of SURMOF thin films and oligomerized by chemical oxidation method. Inside the nanochannels of SURMOFs only short chain oligomers are formed. PEDOT:MOF thin film was found to be electrically conductive. Control of oligomer chain length and fabrication of oligomer:MOF composite on transparent and conductive substrates as thin film, both are of great significance towards future optoelectronic applications of polymer/oligomer:MOF composite. Abstract: Films consisting of surface-anchored metal-organic frameworks (SURMOFs) which are prepared by layer-by-layer deposition techniques can be used as highly oriented crystalline template structures for oligomerization processes. Herein, SURMOF films of Zn(bdc) (1 ) and, Cu(bpdc) (2 ) were prepared, which consist of lamellar ordered 2D MOF sheets forming 1D channels as the host structures for oligomerization of terthiophene (Tth) and, 3, 4-ethylenedioxythiophene (EDOT), respectively. After SURMOF preparation, the pores were filled either with Tth or EDOT and the oligomerization was initiated by oxidizing agents, such as I2 and FeCl3 . Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS), the short chains of polyterthiophene (PTth) and poly(3, 4-ethylenedioxythiophene) (PEDOT) were characterized. FT-IR and Raman spectroscopy further confirmed the presence of oligomers inside the pores of the SURMOFs. Using the SURMOF thin films as template, a homogeneously distributed conductive MOF-PEDOT composite coating can be achieved, with potential applications in optoelectronics.