Syntheses and Properties of Nine-Ring-Fused Linear Thienoacenes

The hetero-Friedel-Crafts-Bradsher Cyclizations with Formation of Ring Carbon-Heteroatom (P, S) Bonds, Leading to Organic Functional Materials

The interest in functional materials possessing improved properties led to development of new methods of their synthesis, which allowed to obtain new molecular arrangements with carbon and heteroatom motifs. Two of the classical reactions of versatile use are the Friedel-Crafts and the Bradsher reactions, which in the new heteroatomic versions allow to replace ring carbon atoms by heteroatoms. In the present work, we review methods of synthesis of C-S and C-P bonds utilizing thia- and phospha-Friedel-Crafts-Bradsher cyclizations. Single examples of C-As and lack of C-Se bond formation, involving two of the closest neighbors of P and S in the periodic table, have also been noted. Applications of the obtained π-conjugated molecules, mainly as semiconducting materials, flame retardants, and resins hardeners, designed on the basis of five- and six-membered cyclic molecules containing ring phosphorus and sulfur atoms, are also included. This comprehensive review covers literature up to August 2020.

Synthesis of Dinaphtho[2,3-d:2',3'-d']anthra[1,2-b:5,6-b']dithiophene (DNADT) Derivatives: Effect of Alkyl Chains on Transistor Properties

To investigate organic field-effect transistor (OFET) properties, a new thienoacene-type molecule, 4,14-dihexyldinaphtho[2,3-d:2’,3’-d’]anthra[1,2-b:5,6-b’]dithiophene (C6-DNADT), consisting of π-conjugated nine aromatic rings and two hexyl chains along the longitudinal molecular axis has been successfully synthesized by sequential reactions, including Negishi coupling, epoxidation, and cycloaromatization. The fabricated OFET using thin films of C6-DNADT exhibited p-channel FET properties with field-effect mobilities (µ) of up to 2.6 × 10⁻² cm² V⁻¹ s⁻¹, which is ca. three times lower than that of the parent DNADT molecule (8.5 × 10⁻² cm² V⁻¹ s⁻¹). Although this result implies that the installation of relatively short alkyl chains into the DNADT core is not suitable for transistor application, the origins for the FET performance obtained in this work is fully discussed, based on theoretical calculations and solid-state structure of C6-DNADT by grazing incidence wide-angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM) analyses. The results obtained in this study disclose the effect of alkyl chains introduced onto the molecule on transistor characteristics.

Toward Soluble 5,10-Diheterotruxenes: Synthesis and Reactivity of 5,10-Dioxatruxenes, 5,10-Dithiatruxenes, and 5,10-Diazatruxenes

The following work presents three general approaches allowing, for the first time, the synthesis of 5,10-diheterotruxene derivatives containing two identical heteroatoms, namely, oxygen OOC, nitrogen NNC, or sulfur SSC. Two of described pathways involve the photocyclization of the corresponding triene 2 as a key step leading to a heptacyclic aromatic system. The third approach is based on the acidic condensation between ninhydrin 14 and benzo[b]heteroole 15. Typical functionalizations of the 5,10-diheterotruxene core have also been presented. In addition, the article discusses the advantages and limitations of the three suggested paths for receiving specific 5,10-diheterotruxene derivatives because the universal method suitable for obtaining molecules with any type of heteroatoms is not known so far.

Indole-Fused Acridone: Synthesis, Structures, Proton Transfer, and Hole-Transport Properties

Three pairs of regioisomers of the planar acridone derivatives (9 vs 10, 11 vs 12, and 13 vs 14), classified as the 1-cyclized compounds (9, 11, and 13) and the 3-cyclized (or 1,3'-cyclized) regioisomers (10, 12, and 14), have been synthesized, and their X-ray structures have been determined. The 1-cyclized compounds have higher yields and lower energies compared with their 3-cyclized isomers. The fluorescence spectra of the intramolecular H-bond containing compounds (9, 11, 13, and 14) consist of two bands (shorter wavelength band for the keto form and longer wavelength band for the enol form) and exhibit the feature of the excited-state intramolecular proton transfer (ESIPT). The density functional theory (DFT) theoretical investigation of the reorganization energy (λ) with respect to molecular symmetry revealed that planar rigid- C_{2 v}-symmetric polycyclic heteroaromatic molecules (such as acridone, 1, and 13) can have low charge-transport barrier (small λ value) and keep the invariance of the molecular point group in the charge-transport process, and therefore can have high hole mobility.

Exploration of SMM behavior of Ln2 complexes derived from thianaphthene-2-carboxylic acid

Observations were made of field-induced SMM property of a dysprosium-based dinuclear complex derived from thianaphthene-2-carboxylic acid ligand.

Synthesis and properties of isoindigo and benzo[1,2-b:4,5-b′]bis[b]benzothiophene oligomers

A series of thienoacene-isoindigo oligomers have been synthesized from novel BBBT bislactam. Their opto-electronic and device characteristics have been investigated.

Bis[1]benzothieno[2,3-d:2′,3′-d′]anthra[1,2-b:5,6-b′]dithiophene: synthesis, characterization, and application to organic field-effect transistors

A straightforward synthetic method of BBTADT having nine aromatic rings fused and evaluation of OFET in polycrystalline films are reported.