Poly­(indacenodithiophene-benzothiadiazole) has received significant interest because of its exceptional hole mobility despite its near-amorphous thin-film morphology and brittleness at low M n. In comparison, poly­(indacenodithiophene-benzopyrollodione) (PIDTBPD) has a lower hole mobility but is exceptionally ductile at similar M n. Herein, we synthesize random indacenodithiophene (IDT) copolymers with varying amounts of incorporated benzothiadiazole and benzopyrollodione (BPD), which introduces varied degrees of backbone twist to each respective polymer system. This allows us to elucidate how the BPD monomer introduction leads to conformational and morphological changes that influence the crack onset strain (CoS) and hole mobility of these near-amorphous IDT copolymers and the rates by which each material property responds to sequentially larger BPD incorporation. Results of density functional theory calculations suggest that BPD introduction does not lead to significant differences in backbone linearity between the studied polymers, and grazing incidence wide-angle X-ray scattering demonstrates that the degree of crystallinity within thin films is not significantly altered. It does, however, lead to a more varied circular distribution of the hexadecyl side chains around the polymer backbone. With increasing BPD incorporation, a crossover point between CoS and hole mobility emerges. At this crossover point, a random copolymer with 30% BPD introduction displays increased CoS and an average hole mobility value equal to that of the PIDTBPD system, suggesting that hole mobility is more sensitive to torsion along the polymer backbone, while the response of the CoS is relatively delayed. The data also suggest that the increase in CoS with increasing BPD content does not arise because of differences in rigidity but because the more circular distribution of the side chains makes polymer chains with sufficient BPD content better able to flow.

Green chemistry and a natural product together provide a cost-effective, safe and scalable solution to create luminophores with suppressed aggregation quenching in organic semiconductors.

Organic hybrid light-emitting diodes (hybrid-LEDs) employ organic dyes as light converters on top of commercial blue inorganic LEDs, replacing incumbent inorganic phosphor light converters synthesized from rare-earth and/or toxic metallic...

Indacenodithiophene (IDT) copolymers are a class of conjugated polymers that have limited long-range order and high hole mobilities, which makes them promising candidates for use in deformable electronic devices. Key to their high hole mobilities is the coplanar monomer repeat units within the backbone. Poly­(indacenodithiophene-benzothiadiazole) (PIDTC16-BT) and poly­(indacenodithiophene-thiapyrollodione) (PIDTC16-TPDC1) are two IDT copolymers with planar backbones, but they are brittle at low molecular weight and have unsuitably high elastic moduli. Substitution of the hexadecane (C16) side chains of the IDT monomer with isocane (C20) side chains was performed to generate a new BT-containing IDT copolymer: PIDTC20-BT. Substitution of the methyl (C1) side chain on the TPD monomer for an octyl (C8) and 6-ethylundecane (C13B) afford two new TPD-containing IDT copolymers named PIDTC16-TPDC8 and PIDTC16-TPDC13B, respectively. Both PIDTC16-TPDC8 and PIDTC16-TPDC13B are relatively well deformable, have a low yield strain, and display significantly reduced elastic moduli. These mechanical properties manifest themselves because the lengthened side chains extending from the TPD-monomer inhibit precise intermolecular ordering. In PIDTC16-BT, PIDTC20-BT and PIDTC16-TPDC1 side chain ordering can occur because the side chains are only present on the IDT subunit, but this results in brittle thin films. In contrast, PIDTC16-TPDC8 and PIDTC16-TPDC13B have disordered side chains, which seems to lead to low hole mobilities. These results suggest that disrupting the interdigitation in IDT copolymers through comonomer side chain extension leads to more ductile thin films with lower elastic moduli, but decreased hole mobility because of altered local order in the respective thin films. Our work, thus, highlights the trade-off between molecular packing structure for deformable electronic materials and provides guidance for designing new conjugated polymers for stretchable electronics.

A comparative study involving bimetallic nickel catalysts designed from disubstituted N,N,N′,N′‐tetra(diphenylphosphanylmethyl)benzene diamine bridging ligands is reported. Catalyst behavior is explored in the Kumada catalyst‐transfer polymerization (KCTP) using poly(3‐hexylthiophene) (P3HT) as the model system. The success of a controlled polymerization is monitored by analyzing monomer conversion, degree of polymerization, end‐group identity, and molecular weight distribution. The characterization of P3HT obtained from KCTP initiated with the bimetallic catalysts shows chain‐growth behavior; however, the presence of Br/Br end‐groups and broader molecular weight distribution reveals a reduced controlled polymerization compared to the commonly employed Ni(dppp)Cl2. The observed increase in intermolecular chain transfer and termination processes in KCTP initiation with the bimetallic catalysts can be attributed to a weaker Ni(0)‐π‐aryl complex interaction, which is caused by increased steric crowding of the coordination sphere.

A strained, cyclic hydrocarbon comprising a meta‐quaterphenyl‐based arc that is clamped by an alkyne tether was synthesized via Yamamoto coupling of a dichloro precursor. DFT calculations (B3LYP/6‐31G*) indicate that the lowest‐energy ground state adopts a twisted, C2 conformation that bears 19.0 kcal/mol of strain energy. X‐ray crystallographic analysis confirms that, in the solid state, the molecule adopts a twisted structure that is similar to the calculated C2 conformation. Exposure of the ortho‐linked dichloro precursor to Yamamoto conditions generates 9,9′‐bisfluorenylidene in high yield.

The Cover Feature shows a young archer carefully aiming his bow at a target in the background. The synthetic target shown in the foreground incorporates a short alkyne linker that clamps a meta‐quaterphenyl group, generating strain much like a taut string creates tension in an archer's bow. To illustrate this effect, a cartoon string threads through the exterior benzene rings of the quaterphenyl unit and tightens in a knot, drawing the benzenes closer together. Photograph courtesy of Alan Richard. More information can be found in the Full Paper by D. K. Frantz et al.