POLYTHIOPHENES AND OLIGOTHIOPHENES IN ZEOLITE HOSTS - CONJUGATED NANOMETER-SIZE FILAMENTS

The polymerization of different thiophenes in the channels of molecula r sieve zeolite hosts is described. Thiophene, 3-methylthiophene, 2,2' -bithiophene, and terthiophene were introduced into dehydrated proton- , Cu(II)- or Fe(III)-containing zeolites (Nay and Na-mordenite) from o rganic solvents or vapor-phase. In the large-pore hosts, green-black p roducts are formed from the monomers within several minutes. Spectrosc opic characterization (IR, UV-NIR) confirms die formation of oxidized polymer chains in the zeolite channels. UV-Near IR reflectance spectra of the zeolite/polythiophene samples exhibit a broad absorption from 500 to about 2500 nm as die bulk and not the resolved spectra of short oligomers, thus fairly long polymer chains are formed in the zeolites . Conducting polymers can be recovered after dissolution of the zeolit e host in HF. 2, 2'-bithiophene and a-terthiophene in acidic H2Y and H 6Y zeolites (2 and 6 protons per super cage/beta-cage) yield yellow-gr een and purple products, respectively. UV-NIR reflectance data indicat e that the acidic zeolite hosts oxidize the thiophene oligomers to yie ld stable radical cations and dications in their channel systems.