RESUMEN
We investigated the ground- and photoexcited-state chiralities of two chiral fluorophores with a rigid framework embedded in two achiral polyurethanes as the solid matrices. As the fluorophores, we used two pairs of atropisomeric binaphthyl derivatives, (R)-(−)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate [(R)-1a] and (R)-(−)-(3,5-dioxa-4-phosphacyclohepta-[2,1-a:3,4-a']dinaphthalen-4-yl)-dimethylamine [(R)-1b], and for comparison, their optical antipodes (S)-1a and (S)-1b. As the solid matrices, we used two soluble achiral polyurethanes (2a and 2b) derived from the naturally occurring myo-inositol as the building block, because these polymers had a high glass transition temperature of ~150 °C. The chiral fluorophores in the polyurethanes emitted circularly polarised luminescence with a high circular anisotropy of ~0.61.5 × 10(-3). Regardless of the matrix, (R)- and (S)-1a had nearly mirror-image chiroptical properties in the ground and photoexcited states, as did (R)- and (S)-1b.
RESUMEN
2,2-Dimethyl-1,3-dioxolane connected to two pyrene moieties through flexible wires in chloroform exhibited cryptochirality in the ground state, as proven by the lack of detectable circular dichroism signals. This cryptochirality was deciphered in the photoexcited state by circularly polarised luminescence signals.
RESUMEN
The fluorescent modes and signs of the circularly polarized luminescence of an axially chiral binaphthyl-pyrene organic fluorophore were successfully controlled by changing from a fluidic chloroform solution to a glassy poly(methyl methacrylate) solid film.
RESUMEN
Tethering four 1- versus 2-naphthyls to the same chiral scaffold derived from tartaric acid led to oppositely signed circularly polarized luminescence (CPL) and circular dichroism (CD) in solution, which not only reveals the decisive role of the spatial arrangement of chromophores/fluorophores in determining the chiroptical behaviors but also provides us with a versatile tool for switching the signs of CPL and CD without using the antipodal scaffold.