In this report we demonstrate that labile intramolecular N→B-Lewis pair formation can serve to tailor the properties of π-conjugated electronic materials.

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 2.38 to 1.20 eV (Flu) and from 2.27 to 1.55 eV (TPCp) via chemical or electrochemical reduction.

Gold(I) chloride complexes of arylisocyanides derived from 9‐benzylidene‐9H‐fluorene (Flu), 5‐benzylidene‐1,2,3,4‐tetraphenylcyclopentadiene (TPCp), and 5‐benzylidene‐5H‐dibenzo[a,d]cycloheptene (Dbs) have been prepared. The crystal structures and electronic properties of the three complexes are discussed. UV/Vis data complemented by DFT calculations indicate that the gold(I) centers act as Lewis acids and increase the acceptor strength of the isocyano group. The metal center therefore indirectly affects the optical properties of the π‐conjugated ligands, but is not directly involved in electronic transitions.

A series of polythiazoles (PvTzs) featuring conjugated styryl sidechains equipped with different solubilizing p‐alkoxy‐groups (OR, R = n‐octyl, n‐dodecyl, 2‐ethylhexyl, 2‐hexyldecyl) is prepared by Negishi‐coupling polycondensation. Soluble material with number‐average molecular weights of up to Mn = 8.5 kDa (polydispersity (PDI) = 1.3, degree of polymerization (DPn) ≈ 20) is obtained, with a head‐to‐tail content of the PvTzs of ≈77%, as estimated from comparison with reference polymers. The polymers exhibit optical absorption properties similar to their polythiophene analogues, while their electrochemical characterization shows a significant stabilization of their frontier orbital levels. Fluorescence measurements indicate that upon excitation of the electron rich alkoxystyryl side‐chains charge transfer onto the more electron deficient polythiazole backbone occurs. This finding is corroborated by density functional theory (DFT) calculations on oligomeric model systems, which also consistently reproduce the optical properties observed for the polymers. The potentialities of these materials for applications in organic electronics can be demonstrated by their use as donor materials in organic photovoltaic cells, which exhibit higher open circuit voltages (VOC, up to 0.86 V) than P3HT‐ or analogous polythiophene‐based cells (VOC = 0.5–0.6 V).

A fulvenyl-functionalized polyisocyanide (PIC2) with a high electron mobility of μe = 10−2 cm2 V−1 s−1 has been incorporated into donor–acceptor block copolymers. Their self-assembly and bulk-morphology have been studied, and potential device applications have been explored.