mz6b00513_si_001.pdf (1.3 MB)
Near-Ultraviolet Circular Dichroism of Achiral Phenolic Termini Induced by Nonchromophoric Poly(l,l‑lactide) and Poly(d,d‑lactide)
journal contribution
posted on 2016-08-11, 16:04 authored by Kai Kan, Michiya Fujiki, Mitsuru Akashi, Hiroharu AjiroHerein,
we
present the first induced chirality of vanillin and its phenolic analogs
attached to the chain ends of poly(l,l-lactide)
and poly(d,d-lactide). Vanillin analogs were used
as chromophoric
and luminophoric, but achiral, ring-opening initiators of corresponding
chiral cyclic lactides. Induced chirality was evident from clear circular
dichroism bands at 270–320 nm due to π–π*
and n−π* transitions at the vanillin moiety. However,
no circularly polarized
luminescence band was detected. Density functional theory (DFT) and
time-dependent DFT calculations suggested the existence of multiple
through-space intramolecular CH/O interactions between the ortho-methoxy moiety of vanillin and nearest-neighbor lactic
acid units. The terminus sensitively indicated whether the main-chain
chirality was l or d.