Curved π-Conjugated Helical Carbon Frameworks: Syntheses, Structural Analyses, and Properties

Abstract

Two enantiomers with helical carbon frameworks (M-HCFa and P-HCFa) and their conformational isomers (M-HCFb and P-HCFb) have been synthesized and characterized. The single-crystal analysis revealed the novel structures in which three propeller blades spiro-fused on two central benzene rings. The optical properties were further investigated, and stable bipolar electrochemiluminescence emissions were discovered for the first time existing in helical carbon frameworks, which provide new insights into the future development of high-performance molecular luminescent devices.

Simultaneous Dehalogenation and Hydrogenation in Sonogashira Coupling

“…Benefiting from Sonogashira coupling, we recently synthesized several curved π-conjugated helical polyynes and reported their intriguing photophysical properties. 20 At present, there are various types of Sonogashira coupling that have been developed, such as asymmetric Sonogashira coupling, 10−12 photocatalytic Sonogashira coupling, 21,22 aqueous Sonogashira coupling, 23,24 and Cu-free Sonogashira coupling. 25,26 Although Sonogashira coupling involving small steric hindrance substrates often proceeds smoothly, it is difficult when steric hindrance from aryl/alkenyl halides and/or terminal alkyne is bulky.…”

“…Based on Sonogashira coupling, numerous interesting alkynyl functional molecules have been synthesized, such as graphyne, , dehydrophenylannulene, − etc. Benefiting from Sonogashira coupling, we recently synthesized several curved π-conjugated helical polyynes and reported their intriguing photophysical properties . At present, there are various types of Sonogashira coupling that have been developed, such as asymmetric Sonogashira coupling, − photocatalytic Sonogashira coupling, , aqueous Sonogashira coupling, , and Cu-free Sonogashira coupling. , …”

Positional Isomeric Thiophene-Based π-Conjugated Chromophores: Synthesis, Structure, and Optical Properties

“…Although those thiophene-based π-conjugated oligomers often possess many interesting photoluminescence (PL) properties, there is no report on their electrochemiluminescence (ECL) so far. Based on our previous work, ECL properties may exist in either planar π-conjugated or curved π-conjugated aryl acetylene oligomers. − Therefore, in order to explore new properties and applications and understand the relationship between the geometries and the properties, we designed and synthesized a series of positional isomeric thiophene-based chromophores (named TCs ), in which ortho -, meta -, and para -phenylene are used as π-bridges to connect the two bis-thiophene moieties (Scheme ). After confirming the structure by 1 H NMR, 13 C NMR, HR MS, and single-crystal X-ray diffraction (XRD) analysis, the ultraviolet–visible (UV–vis) absorption, fluorescence (FL) emission, and electrochemiluminescence (ECL) properties were further investigated.…”