jo3023928_si_001.pdf (3.46 MB)
Role of Free Space and Conformational Control on Photoproduct Selectivity of Optically Pure α‑Alkyldeoxybenzoins within a Water-Soluble Organic Capsule
journal contribution
posted on 2013-02-01, 00:00 authored by Revathy Kulasekharan, Murthy V. S. N. Maddipatla, Anand Parthasarathy, V. RamamurthyOptically pure α-alkyl deoxybenzoins resulting
in products
of Norrish Type I and Type II reactions upon excitation has been investigated
within the octa acid (OA) capsule in water. The product distribution
was different from that in an organic solvent and was also dependent
on the length of the α-alkyl chain. Most importantly, a rearrangement
product not formed in an organic solvent arising from the triplet
radical pair generated by Norrish Type I reaction was formed, and
its yield was dependent on the alkyl chain length. In an organic solvent,
since the cage lifetime is shorter than the time required for intersystem
crossing (ISC) of the triplet radical pair to the singlet radical
pair the recombination with or without rearrangement of the primary
radical pair (phenylacetyl and benzyl) does not occur. Recombination
without rearrangement within the capsule as inferred from monitoring
the racemization of the optically pure α-alkyl deoxybenzoins
suggesting the capsule’s stability for at least 10–8 s (the time required for ISC) is consistent with our previous photophysical
studies that showed partial opening and closing of the capsule in
the time range of microseconds.