Polyynes as Precursors of Photoluminescent Solvent Polarity Probes

A simple and convenient synthesis of substituted thiophenes from pyrrole end-capped polyynes is being reported. The method allows one to obtain a variety of different fluorescent oligo­(hetero)­aryles from polyyne precursors. The resulting thiophenes exhibit strong emission solvatochromism in a wide scope of different solvents which makes them promising candidates for fluorescent solvent polarity probes

Palladium End-Capped Polyynes via Oxidative Addition of 1‑Haloalkynes to Pd(PPh₃)₄

Reported here is the use of 1-haloacetylenes and 1-halopolyynes as synthons for the preparation of new palladium­(II) end-capped polyynes. The 1-haloalkynes were obtained in a series of transformations from <i>para</i>-substituted bromoarenes that included Sonogashira coupling followed by halogenation and chain elongation via Cadiot–Chodkiewicz protocol. The key step for the synthesis of metal complexes was oxidative addition of 1-haloalkynes to Pd­(PPh₃)₄, which allowed obtaining a series of metal compounds <b>1</b>–<b>5</b>-C_<i>n</i>X with carbon chains up to hexatriyne in 75–100% yield. All the compounds were characterized by NMR and HRMS or elemental analysis. The ¹³C spectra of the 1-haloalkynes showed interesting, although expected, shifts of the carbon chain atoms close to the halogen termini. X-ray crystal structures were obtained for three polyynestwo butadiynes (<b>2</b>-C₄[Pd]Br and <b>3</b>-C₄[Pd]­Br) and one hexatriyne (<b>1</b>-C₆[Pd]­Br)and the latter is the first reported X-ray crystal structure of palladium end-capped hexatriyne

Palladium End-Capped Polyynes via Oxidative Addition of 1‑Haloalkynes to Pd(PPh₃)₄

Reported here is the use of 1-haloacetylenes and 1-halopolyynes as synthons for the preparation of new palladium­(II) end-capped polyynes. The 1-haloalkynes were obtained in a series of transformations from <i>para</i>-substituted bromoarenes that included Sonogashira coupling followed by halogenation and chain elongation via Cadiot–Chodkiewicz protocol. The key step for the synthesis of metal complexes was oxidative addition of 1-haloalkynes to Pd­(PPh₃)₄, which allowed obtaining a series of metal compounds <b>1</b>–<b>5</b>-C_<i>n</i>X with carbon chains up to hexatriyne in 75–100% yield. All the compounds were characterized by NMR and HRMS or elemental analysis. The ¹³C spectra of the 1-haloalkynes showed interesting, although expected, shifts of the carbon chain atoms close to the halogen termini. X-ray crystal structures were obtained for three polyynestwo butadiynes (<b>2</b>-C₄[Pd]Br and <b>3</b>-C₄[Pd]­Br) and one hexatriyne (<b>1</b>-C₆[Pd]­Br)and the latter is the first reported X-ray crystal structure of palladium end-capped hexatriyne

Use of Stable Amine-Capped Polyynes in the Regioselective Synthesis of Push–Pull Thiophenes

The reactions of a series of 1-halopolyynes with secondary amines led to novel amine end-capped polyynes exhibiting surprisingly high stability toward moisture. The new compounds were characterized by NMR spectroscopy, ESI-MS spectrometry, and X-ray single-crystal diffractometry. The use of amine end-capped polyynes as precursors to substituted push–pull thiophenes was next presented. The results show the firstto the best of our knowledgetransformation of ynamine to thiophene and the first regioselective transformation of a longer polyynes to butadiyne-substituted thiophene. Photophysical studies of the resulting compounds show that some of the substituted thiophenes have high quantum yield photoluminescence upon UV light irradiation

Use of Stable Amine-Capped Polyynes in the Regioselective Synthesis of Push–Pull Thiophenes

The reactions of a series of 1-halopolyynes with secondary amines led to novel amine end-capped polyynes exhibiting surprisingly high stability toward moisture. The new compounds were characterized by NMR spectroscopy, ESI-MS spectrometry, and X-ray single-crystal diffractometry. The use of amine end-capped polyynes as precursors to substituted push–pull thiophenes was next presented. The results show the firstto the best of our knowledgetransformation of ynamine to thiophene and the first regioselective transformation of a longer polyynes to butadiyne-substituted thiophene. Photophysical studies of the resulting compounds show that some of the substituted thiophenes have high quantum yield photoluminescence upon UV light irradiation

Transition-Metal Free Mechanochemical Approach to Polyyne Substituted Pyrroles

In this contribution, the synthesis of long chain hexatriynyl- and octatetraynyl-substituted pyrroles in one step from 1-halopolyyne precursors is reported. The products were obtained via a mechanochemical approach by simple grinding of 1-haloalkynes with <i>N</i>-substituted pyrroles and potassium carbonate which played a role of heterogeneous catalyst and this solvent- and transition metal-free approach is unprecedent in the synthesis of new, organic, long chain polyynes. Additionally, an extensive X-ray single crystal study of pyrrole end-capped polyynes is presented. Such compounds are possible substrates for different oligoheterocycles and have a significant application potential such as for instance molecular wires

Transition-Metal Free Mechanochemical Approach to Polyyne Substituted Pyrroles

In this contribution, the synthesis of long chain hexatriynyl- and octatetraynyl-substituted pyrroles in one step from 1-halopolyyne precursors is reported. The products were obtained via a mechanochemical approach by simple grinding of 1-haloalkynes with <i>N</i>-substituted pyrroles and potassium carbonate which played a role of heterogeneous catalyst and this solvent- and transition metal-free approach is unprecedent in the synthesis of new, organic, long chain polyynes. Additionally, an extensive X-ray single crystal study of pyrrole end-capped polyynes is presented. Such compounds are possible substrates for different oligoheterocycles and have a significant application potential such as for instance molecular wires