Covalent functionalization of single-walled carbon nanotubes with polytyrosine: Characterization and analytical applications for the sensitive quantification of polyphenols

This work reports the synthesis and characterization of single-walled carbon nanotubes (SWCNT) covalently functionalized with polytyrosine (Polytyr); the critical analysis of the experimental conditions to obtain the efficient dispersion of the modified carbon nanotubes; and the analytical performance of glassy carbon electrodes (GCE) modified with the dispersion (GCE/SWCNT-Polytyr) for the highly sensitive quantification of polyphenols. Under the optimal conditions, the calibration plot for the amperometric response of gallic acid (GA) shows a linear range between 5.0 × 10⁻⁷ and 1.7 × 10⁻⁴ M, with a sensitivity of (518 ± 5) m AM⁻¹ cm⁻², and a detection limit of 8.8 nM. The proposed sensor was successfully used for the determination of total polyphenolic content in tea extracts.     

Factors affecting the competitive reduction of 8,8-dimethylnaphthalene-1,4,5(8H)-trione in a Diels–Alder cycloaddition with hydroxysulfinyldienes

Competing reduction and cycloaddition products were formed in the reaction of 8,8-dimethylnaphthalene-1,4,5(8H)-trione with a hydroxysulfinyldiene. The ratio of reduction to cycloaddition products depended on the stereochemistry of the diene and on the solvent employed, being higher in ethanol than in benzene. The ratio was also affected by the addition of Lewis acids, decreasing in the order BF₃ = Al₂O₃ > MgCl₂ > ZnCl₂. The results help to explain and predict the occurrence of these competing processes in Diels–Alder cycloadditions involving quinonedienophiles.     

Benzotrithiophene versus Benzo/Naphthodithiophene Building Blocks: The Effect of Star‐Shaped versus Linear Conjugation on Their Electronic Structures

The synthesis, characterization, and optical properties of a novel star‐shaped oligothiophene with a central rigid trithienobenzene (BTT) core and diketopyrrolopyrrole (DPP) units are reported and compared with homologous linear systems based on the benzodithiophene (BDT) and the naphthodithiophene (NDT) units end capped with DPPs. This comparison is aimed at elucidating the effect of the star‐shaped configuration versus linear conformation on the optical and electrical properties. Electronic and vibrational spectroscopies, together with transient absorption spectroscopy, scanning electronic microscopy, and DFT calculations are used to understand not only the molecular properties of these semiconductors, but also to analyze the supramolecular aggregation in these derivatives. We conclude that although the subject star‐shaped derivative is not optimal in terms of π‐conjugation, its extended BTT unit significantly favors intermolecular π‐stacking interactions, which is interesting for their applications in devices. Field‐effect transistors and solar cells were fabricated with these new molecular semiconductors and the performance difference discussed.