Structure and spectroscopy of two new bases for building block: Terpyridine derivatives

Two new terpyridine compounds are reported: 4′-(3-methyl-2-thienyl)-4,2′:6′,4″-terpyridine, C₂₀H₁₅N₃S, (I) and 4′-(4-quinolinyl)-4,2′:6′,4″-terpyridine, C₂₅H₁₇C_l3N₄, (II). Both structures crystallize in centrosymmetric space groups and present weak H-bonds, which gives greater stability to their structures. Light absorption by both molecules is firmly established on the experimental and the TDDFT analysis as coming from π → π∗transitions. The fluorescence of both compounds has a small Stockes shift, which is also consistent with the emission from highly rigid molecules. Furthermore, the thermal stability observed for both compounds, until about 280 °C, making these molecules interesting candidates for use as complex ligands, which are obtained by means of solvothermal synthesis (technique with temperatures of about 150 °C).