Synthesis and Electronic Structure of Ferrocenylborane-Modified Quaterthiophenes and Polythiophenes

Abstract

Polythiophene was functionalized with redox-active ferrocenylborane pendent groups. A postpolymerization modification procedure was applied, in which silylated polythiophene was reacted with BBr 3 to give a polymer with pendent BBr 2 groups. The dibromoboryl functionalities were then further elaborated by first treating the intermediate with FcSnMe 3 to introduce the ferrocenyl moieties and then with an arylcopper derivative ArCu (Ar = 2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tip)) to sterically stabilize the boron centers. Using similar methods, two quaterthiophene derivatives were also prepared. The number-average molecular weight (M n ) of the polymers was determined by gel permeation chromatography (GPC) relative to narrow PS standards to range from 9400 to 14 600 Da. The polymer structure was further confirmed by MALDI-TOF mass spectrometry and by multinuclear NMR spectroscopy. H,H-NOESY spectroscopy and single crystal X-ray diffraction experiments on the quaterthiophene derivatives were used to gain insight into the conformation of the oligomers and polymers in solution and the solid state. The electronic structure of the oligo-and polythiophenes was studied in detail by UV-vis spectroscopy and electrochemical measurements.

Polymers with pendant ferrocenes

“…As an example, borylated polystyrene derivatives with pendant electron-rich ferrocene moieties at boron along with aryl groups have been prepared via post-synthetic modification of the corresponding dibromoborane with trimethylstannyl ferrocene (Scheme 8). 36,37 3. Polymer properties…”

“…Anion complexation with fluoride has been studied and showed a distinct polymer effect compared with analogous low molecular model compounds. 36,37 For redox polymers immobilized on electrode surfaces both the spacer between the redox center and the polymer backbone and the distance between the redox center and the electrode surface become relevant. Therefore, the preparation of block copolymer brushes with varying sequences and chain lengths of FcMA segments was conducted to interrogate the effects of spacing from the indium tin oxide (ITO) electrode surface on the electrochemical properties of a tethered electroactive film (Scheme 15).…”

Turn-on fluorescence response upon anion binding to dimesitylboryl-functionalized quaterthiophene

“…4 Straightforward detection schemes based on changes in the absorption or emission color upon analyte binding have been developed, by taking advantage of the extended p-conjugation in tricoordinate organoboranes that originates from overlap of the empty p-orbital with p-conjugated substituents. 9,10 We demonstrated that introduction of the boryl groups greatly affects the electronic structure of the conjugated thiophene main chain, leading to lowering of the LUMO energy level and a red-shifted absorption due to narrowing of the HOMO-LUMO gap. Upon anion binding to B, the extended conjugation pathway is interrupted, which results in a distinct change in the absorption color and luminescence properties.…”

Synthetic Approaches to Triarylboranes from 1885 to 2020

“…[92] Both monomeric and polymeric boron-containing systemsw ere synthesized from aryldibromoboranes and organotin reagents (vide supra, Scheme14; vide infra, Scheme 29). They subsequently used this strategy for similar applications with slight modifications of the synthetic procedure, the third aryl group being added via at in, [92] a copper [124][125][126] or aG rignardr eagent [127] (Scheme 29).…”