Self-Assembly of a Donor–Acceptor Nanotube. A Strategy To Create Bicontinuous Arrays

The self-assembly of bolaamphiphile <b>1</b> into nanotubes containing a nanostructured electron donor/acceptor heterojunction is reported. In 10% MeOH/H₂O, the tetraphenylporphyrin (TPP) and 1,4,5,8-naphthalenetetracarboxylic acid diimide chromophores engage in strong <i>J</i>-type π–π interactions within monolayer rings that further stack into the nanotube assemblies. In 10% MeOH/H₂O at pH 1 or 11 or in pure MeOH, assembly is driven exclusively by the TPP ring, leading to the formation of nonspecific, unstructured aggregates. Steady-state, time-resolved fluorescence and femtosecond transient absorption spectroscopy revealed a strong dependence of the fluorescence decay and electron-transfer/charge-recombination time constants on the nature of the assemblies. These studies highlight the importance of local nanostructure in determining the photophysical properties of optoelectronic materials

Scope and Regioselectivity of Iridium-Catalyzed C–H Borylation of Aromatic Main-Chain Polymers

An efficient functionalization of aromatic main-chain polymers was established using a combination of iridium-catalyzed borylation of aromatic C–H bonds and the Suzuki–Miyaura coupling reaction. Comparative studies of various iridium catalysts and borylation reagents show that [Ir­(OMe)­(COD)]₂ is significantly more active than [IrCl­(COD)]₂, and bis­(pinacolato)­diboron induces higher efficiency than pinacolborane. The regioselectivity of the borylation was investigated using model compounds that mimic the repeating unit structure of poly­(arylene ether sulfone). The C–H bonds of the sulfone model compound were more reactive than those of the bisphenol model compound, and the borylation occurred preferentially at the meta position to the sulfone moiety owing to steric hindrance and electronic effects. The glass transition temperature of the borylated polymer increases with increasing concentration of pinacolboronic ester group. The pinacolboronic ester group could be conveniently converted to boronic acid [B­(OH)₂] and potassium trifluoroborate (BF₃K), which could also serve as versatile reactive sites for the synthesis of a wide range of functionalized polymers via Suzuki–Miyaura couplings