Room-Temperature Reversibleσ-Dimerization of a Phenalenyl Radical

Phenalenyl derivatives have been of tremendous interest due to their reversible dimerization in response to the external stimuli such as temperature.However,most of PLY derivatives only show the reversibility dependent on temperature.Herein,we report a unique PLY-based radical anionic salt with reversibleσ-dimerization controlled by solvent rather than temperature.The structure and reversibility of this PLY anion system have been spectroscopically,crystallographically,and theoretically investigated.The molecule exists mainly as theσ-dimer form of K2[σ-12]in toluene,while it can be broken into the monomeric radical anion 1•–by re-dissolving in THF.Moreover,when THF is replaced with toluene,radical 1•–could beσ-dimerized back again.Theoretical calculations reveal that the potassium ions are necessary for the formation of theσ-dimer and the solvent polarity controls theσ-dimerization by regulating the presence of K+.

基于合作能量传递的Sm^(2+)离子上转换发光

报道了Sm^(2+)离子的上转换发光。在实验上证明了变价镧系离子同样可以作为上转换材料的发光中心。在近红外光的激发下,复合Ba FCl_(0.5)Br_(0.5)∶1%Sm^(2+)-Ca F_2∶1%Yb^(3+)化合物发出红色上转换发光。上转换发射光谱中位于631,644,665,689,704,729 nm的特征发射分别来自于样品中Sm^(2+)的~5D_i(i=0,1)→~7F_j(j=0,1,2)特征跃迁。根据动力学分析及光子数拟合的结果,我们将二价Sm离子的上转换过程归因于合作能量传递,即:两个同时被激发的Yb^(3+)离子合作将能量传递给一个Sm^(2+)离子。