Facultad de Química, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain.
J Org Chem. 2011 May 20;76(10):3837-45. doi: 10.1021/jo200204u. Epub 2011 Apr 15.
A series of 4-arylvinyl-2,6-di(pyridin-2-yl)pyrimidines have been efficiently prepared by a double cross-coupling reaction between 2,4-dichloro-6-methylpyrimidine and 2-(tributylstannyl)pyridine, followed by aldol condensation with the appropriate aromatic aldehyde substituted with electron-donating, electron-withdrawing, dendritic, or water-soluble groups. The effect of different protic and aprotic solvents on the optical absorption and emission properties of these systems was studied. Compounds with electron-donating groups display strong emission solvatochromism, suggesting the formation of an intramolecular charge-separated emitting state. The solvatochromic behavior depends not only on the solvent polarity but also on the hydrogen bonding parameters of the solvent. The effect of protonation was also studied, and the abilities of some of these molecules to function as colorimetric and luminescent pH sensors were demonstrated with dramatic color changes and luminescence switching upon the introduction of acid.
一系列 4-芳基乙烯基-2,6-二(吡啶-2-基)嘧啶已通过 2,4-二氯-6-甲基嘧啶和 2-(三丁基锡基)吡啶之间的双交叉偶联反应以及与具有供电子、吸电子、树枝状或水溶性基团取代的合适芳醛的醛缩合反应高效制备。研究了不同质子和非质子溶剂对这些体系的光吸收和发射性质的影响。具有供电子基团的化合物显示出强烈的发射溶剂化变色，表明形成了分子内电荷分离发射态。溶剂化变色行为不仅取决于溶剂的极性，还取决于溶剂的氢键参数。还研究了质子化的影响，并且一些分子能够作为比色和发光 pH 传感器的能力得到了证明，在引入酸时会发生剧烈的颜色变化和发光开关。
