Redox‐Active Heteroatom‐Functionalized Polyacetylenes

Abstract

The discovery of metallic conductivity in polyacetylene [‐HC=CH‐]n upon doping represents a landmark achievement. However, the insolubility of polyacetylene and a dearth of methods for its chemical modification have limited its widespread use. Here, we employ a ring‐opening metathesis polymerization (ROMP) protocol to prepare functionalized polyacetylenes (fPAs) bearing: (1) electron‐deficient boryl (‐BR2) and phosphoryl (‐P(O)R2) side chains; (2) electron‐donating amino (‐NR2) groups, and (3) ring‐fused 1,2,3‐triazolium units via strain‐promoted Click chemistry. These functional groups render most of the fPAs soluble and can lead to intense light absorption across the visible to near‐IR region. Also, the presence of redox‐active boryl and amino groups leads to opposing near‐IR optical responses upon (electro)chemical reduction or oxidation. Some of the resulting fPAs show greatly enhanced air stability when compared to known polyacetylenes. Lastly, these fPAs can be cross‐linked to yield network materials with the full retention of optical properties.

MOF-based colorimetric sensor for rapid and visual readout of trace acetylene

“…It became more prominent with time lapsing and evolved to a broad and intense absorption peak at 511 nm (1.66 eV) at around 30 min. It has been established that the functionalized polyacetylene possesses HOMO–LUMO gaps ranging from 1.55 to 1.75 eV, 35 corresponding to the newly formed absorption peak in the present study (Fig. 3b and S22†).…”

Multicomponent Synthesis of Poly(α-aminophosphine chalcogenide)s and Subsequent Depolymerization

“…The GPC analysis was inconsistent with M w data obtained by both end-group analysis and DOSY ( vide infra ), likely because of the interactions between the polar PCh (EN; P = 2.19, O = 3.44, S = 2.58) and N–H functional groups and the stationary phase of the GPC column. Similar incompatibility of inorganic polymers with GPC columns has been acknowledged. , The notable low solubility of 4 – 7 likely also biases the M W values toward the more soluble oligomeric molecules. This prompted the analysis of chain lengths by alternative experimental means.…”

The Green Box: Selenoviologen-Based Tetracationic Cyclophane for Electrochromism, Host–Guest Interactions, and Visible-Light Photocatalysis

“…Bridging of main group elements (P, S, Se, Te, and Bi) in the bipyridine bay, as an effective modification method for viologens (V 2+ ), is developed to improve their optoelectronic properties and stabilization of cationic radical. − Among the heteroatoms-bridged viologens, selenoviologen (SeV 2+ ) has been reported as a photosensitizer as well as an electron-transfer mediator in visible-light photocatalysis, benefiting from the superior properties of its radical cations (SeV +• ). − Recently, two SeV 2+ -appendant metallacycles with highly stable radical cations and long-lived charge separation were reported, which were used for electrochromism and visible-light-induced cross-dehydrogenative coupling . It can be envisioned that introducting selenoviologens into cationic cyclophanes can not only narrow highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO–LUMO) energy gaps and improve the photophysical properties of tetracationic cyclophane but also enchance the stability of biradical dicationic species (V 2(+•) ) and retard the charge recombination of tetracationic species (V 4+ ), which are extremely essential for tetracationic cyclophane derivatives in visible-light photocatalysis.…”