Electronic Spectroscopy of Methylcyanodiacetylene (CH3 C5 N)

Synthesis and Electronic Phosphorescence of Dicyanooctatetrayne (NC10N) in Cryogenic Matrixes

The rodlike 1,8-dicyano-octa-1,3,5,7-tetrayne (NC₁₀N) molecule was synthesized with UV-assisted coupling of rare-gas matrix-isolated cyanobutadiyne (HC₅N) molecules. Detection of NC₁₀N molecule was possible due to its strong orange-red (origin at 618 nm) electronic luminescence. Excitation spectra of this emission (ã ³Σ_u⁺-X̃ ¹Σ_g⁺ phosphorescence) gave access to studying the fully allowed H̃ ¹Σ_u⁺-X̃ ¹Σ_g⁺ UV system of NC₁₀N. The identification of observed spectral features was assisted with quantum chemical computations. Certain regularities shaping the electronic spectroscopy of NC_{2 n}N molecules have been discussed.

Low Temperature Synthesis and Phosphorescence of Methylcyanotriacetylene

This paper reports on UV-stimulated synthesis of methylcyanotriacetylene carried out in cryogenic rare gas matrixes via coupling of smaller precursors: propyne and cyanodiacetylene. The detection was possible due to the strong visible ã ³A' → X̃ ¹A₁ phosphorescence of CH₃C₇N, discovered in the course of this work. The ensuing measurements of electronic spectroscopy revealed the formally forbidden B̃ ¹E-X̃ ¹A₁ system, as well as the allowed one Ẽ ¹A₁-X̃ ¹A₁, with origins at approximately 3.32 and 5.4 eV, respectively. It was also possible to revisit the spectroscopic characterization of cyanotriacetylene, HC₇N, formed in parallel to the title photoproduct. Spectral assignments were assisted with a density functional theory study.