Syntheses and properties of π-conjugated oligomers containing furan-fused and thiophene-fused aromatic units

Supramolecular polymerization of electronically complementary linear motifs: anti-cooperativity by attenuated growth

Anti-cooperative supramolecular polymerization by attenuated growth exhibited by self-assembling units of two electron-donor benzo[1,2-b:4,5-b']dithiophene (BDT) derivatives (compounds 1a and 1b) and the electron-acceptor 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) (compound 2) is reported. Despite the apparent cooperative mechanism of 1 and 2, AFM imaging and SAXS measurements reveal the formation of small aggregates that suggest the operation of an anti-cooperative mechanism strongly conditioned by an attenuated growth. In this mechanism, the formation of the nuclei is favoured over the subsequent addition of monomeric units to the aggregate, which finally results in short aggregates. Theoretical calculations show that both the BDT and BODIPY motifs, after forming the initial dimeric nuclei, experience a strong distortion of the central aromatic backbone upon growth, which makes the addition of successive monomeric units unfavourable and impedes the formation of long fibrillar structures. Despite the anti-cooperativity observed in the supramolecular polymerization of 1 and 2, the combination of both self-assembling units results in the formation of small co-assembled aggregates with a similar supramolecular polymerization behaviour to that observed for the separate components.

Buchwald-Hartwig Amination of Aryl Halides with Heterocyclic Amines in the Synthesis of Highly Fluorescent Benzodifuran-Based Star-Shaped Organic Semiconductors

The study of palladium-catalyzed amination of bromobenzene with aromatic and heterocyclic amines, widely used in the synthesis of organic semiconductors, was performed. The best conditions for the coupling of aryl bromides with carbazole, diphenylamine, phenoxazine, phenothiazine, 9,9-dimethyl-9,10-dihydroacridine, and their derivatives have been developed. Based on the results, nine new star-shaped organic semiconductors, exhibiting up to 100% fluorescent quantum yield in the 400-550 nm range, have been synthesized in good yields. The TDDFT calculations of the absorption spectra revealed a good correlation with experimental results and slight solvatochromic effects with a change in the polarity of the solvent.

A Raman Spectroscopic and Computational Study of New Aromatic Pyrimidine-Based Halogen Bond Acceptors

Two new aromatic pyrimidine-based derivatives designed specifically for halogen bond directed self-assembly are investigated through a combination of high-resolution Raman spectroscopy, X-ray crystallography, and computational quantum chemistry. The vibrational frequencies of these new molecular building blocks, pyrimidine capped with furan (PrmF) and thiophene (PrmT), are compared to those previously assigned for pyrimidine (Prm). The modifications affect only a select few of the normal modes of Prm, most noticeably its signature ring breathing mode, ν1. Structural analyses afforded by X-ray crystallography, and computed interaction energies from density functional theory computations indicate that, although weak hydrogen bonding (C–H···O or C–H···N interactions) is present in these pyrimidine-based solid-state co-crystals, halogen bonding and π-stacking interactions play more dominant roles in driving their molecular-assembly.

The anion impact on the self-assembly of naphthalene diimide diimidazolium salts

Self-assembly behavior of naphthalene diimide diimidazolium salts was analyzed as a function of their anions. Changes in the anion nature significantly impact the properties of aggregates.

A Furan-Thiophene-Based Quinoidal Compound: A New Class of Solution-Processable High-Performance n-Type Organic Semiconductor

The furan-thiophene-based quinoidal organic semiconductor, TFT-CN, is designed and synthesized. TFT-CN displays a high electron mobility of 7.7 cm(2) V(-1) s(-1) , two orders of magnitude higher than the corresponding thiophene-based derivative.

Self-assembly of fluorescent diimidazolium salts: tailor properties of the aggregates changing alkyl chain features

Self assembly of fluorescent diimidazolium NDI salts showed properties of aggregates changing with alkyl chain length, with an odd–even effect.

π-Conjugated diimidazolium salts: rigid structure to obtain organized materials

The photophysical properties and aggregation ability of π-conjugated diimidazolium salts were studied in solution and in the solid state. Experimental investigations were supported by DFT calculations.