Swapping Circularly Polarised Luminescence of Eu(III)‐Binaphthyl Hybridized Luminophore with and without Oxymethylene Spacer

Chiroptical signs in circularly polarised luminescence (CPL) of Eu(III) luminophores coordinated to C2‐symmetric binaphthyl ring carrying carboxylic acids, (R)‐1 (and (S)‐1)) and (R)‐2 (and (S)‐2)) were inverted by inserting two oxymethylene spacers between the ring and the acids. The subtle difference in reorganization between (R)‐1 and (R)‐2 causes the apparent CPL sign‐swapping characteristics. We assume that (R)‐2 is more likely to undergo this reorganization rather than (R)‐1 because of the highly flexible spacer and vice versa. The subtle difference in the rotational freedom of the ligands with and without the two spacers causes the opposite CPL signs although (R)‐1/Eu and (R)‐2/Eu had the same CD sign in the ground state. This was proven by experimental and theoretical data. Chiroptical signs in CPL of Eu(III) luminophores coordinated to two binaphthyl derivatives (1 and 2) with carboxylic acids were inverted by inserting two oxymethylene spacers between the rings and the acids. The subtle difference in the rotational freedom of the ligands causes the opposite CPL signs, although 1/Eu and 2/Eu had the same CD sign in the ground state.