Temperature-, Concentration-, and Solvent-Dependent M / P Helicity Switching of Double-Helical Monometallofoldamers with Inversion of Circularly Polarized Luminescence

High Resolution Image Download MS PowerPoint Slide Fluorescent double-helical monometallofoldamers [Ag( 1 ) 2 ][PF 6 ] were constructed by the mononuclear complexation of two bipyridine strands 1 featuring two L-shaped dibenzopyrrolo[1,2- a ][1,8]naphthyridine units at both ends with a Ag(I) cation. These monometallofoldamers exhibited double-helical/open conformational switching. [( R )-Ag( 1c ) 2 ][PF 6 ] with chiral side chains induced a single-handed helix sense and enabled precise control of M / P helicity switching in response to a solvent. This complex also exhibited strong fluorescence and circularly polarized luminescence (CPL) inversion switching upon M / P helicity inversion. For instance, [( R )-Ag( 1c ) 2 ][PF 6 ] exhibited positive CPL in CH 2 Cl 2 (φ F = 0.69, g lum = 1.9 × 10 –3 ) and negative CPL in toluene (φ F = 0.79, g lum = −2.0 × 10 –3 ). This double helix also aggregated in polar solvents, which led to CPL inversion switching induced by temperature- and concentration-dependent aggregation.