Fulvenyl-Functionalized Polyisocyanides: Cross-Conjugated Electrochromic Polymers with Variable Optical and Electrochemical Properties

• DOI: 10.1021/acs.macromol.8b00977
• Publication Date: 2018-07-11T16:54:24Z
• Authors: Sandra Schraff; Yu Sun; Frank Pammer
• Keywords: 01 natural sciences; 0104 chemical sciences

We describe the preparation of arylisocyanide monomers bearing conjugated fulvenyl groups derived from 9-benzylidene-9H-fluorene (Flu), 5-benzylidene-1,2,3,4-tetraphenylcyclopentadiene (TPCp), and 5-benzylidene-5H-dibenzo[a,d]cycloheptene (Dbs). The electrochemical and optical properties of the monomers and their precursors have been characterized and consistently showed the effect of the conjugation of the respective functional group (−NO2, −NH2, −NHCHO, and −N≡C) with the fulvenyl moiety. The isocyanides have been subsequently polymerized to the corresponding polyisocyanides (PICs), which exhibited number-average molecular weights of 124–136 kDa (PDI = 2.0–2.7), as determined by gel permeation chromatography in THF vs polystyrene standards. The thermal, optical, and electrochemical properties of the polymers have been studied in detail. Spectroelectrochemical analyses of polymers equipped with redox-active pentafulvene groups show reversible electrochromism, which allows to lower the optical gap from 2....