Saleh Nidal, Moore Barry, Srebro Monika, Vanthuyne Nicolas, Toupet Loïc, Williams J A Gareth, Roussel Christian, Deol Kirandeep K, Muller Gilles, Autschbach Jochen, Crassous Jeanne
Institut des Sciences Chimiques de Rennes, UMR 6226, Institut de Physique de Rennes, UMR 6251, Campus de Beaulieu, CNRS-Université de Rennes 1, 35042 Rennes Cedex (France).
Chemistry. 2015 Jan 19;21(4):1673-81. doi: 10.1002/chem.201405176. Epub 2014 Nov 21.
Electronic circular dichroism and circularly polarized luminescence acid/base switching activity has been demonstrated in helicene-bipyridine proligand 1 a and in its "rollover" cycloplatinated derivative 2 a. Whereas proligand 1 a displays a strong bathochromic shift (>160 nm) of the nonpolarized and circularly polarized luminescence upon protonation, complex 2 a displays slightly stronger emission. This strikingly different behavior between singlet emission in the organic helicene and triplet emission in the organometallic derivative has been rationalized by using quantum-chemical calculations. The very large bathochromic shift of the emission observed upon protonation of azahelicene-bipyridine 1 a has been attributed to the decrease in aromaticity (promoting a charge-transfer-type transition rather than a π-π* transition) as well as an increase in the HOMO-LUMO character of the transition and stabilization of the LUMO level upon protonation.
在螺旋烯-联吡啶前体配体1a及其“翻转”环金属化衍生物2a中已证明了电子圆二色性和圆偏振发光的酸碱切换活性。前体配体1a在质子化时非偏振和圆偏振发光显示出强烈的红移（>160 nm），而配合物2a显示出稍强的发射。通过量子化学计算解释了有机螺旋烯中的单线态发射与有机金属衍生物中的三线态发射之间这种显著不同的行为。氮杂螺旋烯-联吡啶1a质子化时观察到的发射的非常大的红移归因于芳香性的降低（促进电荷转移型跃迁而非π-π*跃迁）以及跃迁的HOMO-LUMO特征的增加和质子化时LUMO能级的稳定化。
