A Boron-Bridged Tetrathiaporphyrinogen

Abstract

Lewis acid and Lewis base centers are simultaneously present in the boron-bridged thiophene-containing porphyrinogen 1 that has been synthesized in high yield. Its crystal structure reveals a nonplanar macrocycle; this and the colorless aspect suggest the absence of a delocalized π-electron system. R = NiPr .

A Family of Main-Chain Polymeric Lewis Acids: Synthesis and Fluorescent Sensing Properties of Boron-Modified Polythiophenes

“…1.2−1.5. MALDI-TOF-TOF with benzo[ a ]pyrene/pyridine as the matrix showed peak patterns that correspond predominantly to linear polymers with the expected −Th 2 B(Ar)− repeating unit and bithiophene end groups (Figure ) . This indicates that the polymerization is not limited by solubility but rather by a small amount of destannylated bithiophene, which may form in the presence of trace amounts of protic acids.…”

Highly Luminescent, Electron-Deficient Bora-cyclophanes

“…In addition, the unusual electronic properties of conjugated organoborane oligomers and polymers that result from p-π overlap of the empty p-orbital on boron with π-conjugated organic groups continue to fascinate researchers as they suggest potential applications in optoelectronic devices . However, although several reports on boron-containing macrocycles have appeared in the literature, in most cases the Lewis acidity of boron is low due to π-overlap with amino or alkoxy substituents or the borons are tetracoordinate, and thus no significant electron delocalization is present . Herein we describe a rational approach to hitherto unprecedented bora-cyclophanes that feature multiple highly electron-deficient organoborane moieties as an integral part of the ring system and thus constitute the first “charge-reverse” analogues of electron-donating macrocycles such as porphyrins, phthalocyanines, calixarenes, oligopyrrols, and recently introduced triarylamine-based aza-cyclophanes. , We also discuss the effect of cyclization on optical and electronic characteristics and present preliminary results on the complexation of anions, which can act as a stimulus to turn the electron-deficient macrocycle into an electron-rich one.…”

Synthesis and Structure‐Property Relationships in Regioisomeric Alternating Borane‐Terthiophene Polymers

“…They are also related to tetrameric thienylboranes, introduced by Siebert et al and referred to as "tetrathiaporphyrinogens", but the latter contain electron-donating amino groups on boron that limit the electron-deficient character. [21] More recently, He et al reported 3,3'-borylated bithiophene dimers (dibora [10]annulenes) that could be isolated and crystallographically characterized, and related studies were disclosed subsequently by Helten et al [12m,22] The reasons for the wider molecular weight distribution and observation of cyclic species with additional thienylene units for PFB3T'-B remain not well understood. Given that the brominated monomer used in the synthesis of PFB3T'-B was prepared from the respective iodinated species it is possible that the presence of traces of an iodo species in the polymerization mixture influenced the polymerization process.…”