PMID- 20192161
OWN - NLM
STAT- MEDLINE
DCOM- 20100908
LR  - 20121115
IS  - 1520-5827 (Electronic)
IS  - 0743-7463 (Linking)
VI  - 26
IP  - 11
DP  - 2010 Jun 1
TI  - Supramolecular photochemistry in beta-cyclodextrin hosts: a TREPR, NMR, and CIDNP 
      investigation.
PG  - 8971-80
LID - 10.1021/la904788t [doi]
AB  - A systematic investigation of the photochemistry and ensuing radical chemistry of 
      three guest ketones encapsulated in randomly methylated beta-cyclodextrin 
      (beta-CD) hosts is reported. Dibenzyl ketone (DBK), deoxybenzoin (DOB), and 
      benzophenone (BP) triplet states are rapidly formed after photolysis at 308 nm. 
      Time-resolved electron paramagnetic resonance (TREPR) spectroscopy, steady-state 
      NMR spectroscopy, and time-resolved chemically induced nuclear polarization 
      (TR-CIDNP) experiments were performed on the ketone/CD complexes and on the 
      ketones in free solution for comparison. The major reactivity pathways available 
      from these excited states are either Norrish I alpha-cleavage or H-atom 
      abstraction from the interior of the CD capsule or the solvent. The DOB triplet 
      state undergoes both reactions, whereas the DBK triplet shows exclusively 
      alpha-cleavage and the BP triplet shows exclusively H-atom abstraction. Radical 
      pairs are observed in beta-CDs by TREPR, consisting of either DOB or BP ketyl 
      radicals with sugar radicals from the CD interior. The TREPR spectra acquired in 
      CDs are substantially broadened due to strong spin exchange. The electron spin 
      polarization mechanism is mostly due to S-T(0) radical pair mechanism (RPM) in 
      solution but changes to S-T(-) RPM in the CDs due to the large exchange 
      interaction. The TR-CIDNP results confirm the reactivity patterns of all three 
      ketones, and DOB shows strong nuclear spin polarization from a novel 
      rearrangement product resulting from the alpha-cleavage reaction.
FAU - Krumkacheva, Olesya A
AU  - Krumkacheva OA
AD  - International Tomography Center, Institutskaya 3a, Novosibirsk 630090, Russia.
FAU - Gorelik, Vitaly R
AU  - Gorelik VR
FAU - Bagryanskaya, Elena G
AU  - Bagryanskaya EG
FAU - Lebedeva, Natalia V
AU  - Lebedeva NV
FAU - Forbes, Malcolm D E
AU  - Forbes MD
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Langmuir
JT  - Langmuir : the ACS journal of surfaces and colloids
JID - 9882736
RN  - 0 (beta-Cyclodextrins)
RN  - JV039JZZ3A (betadex)
SB  - IM
MH  - Magnetic Resonance Spectroscopy/*methods
MH  - *Photochemistry
MH  - beta-Cyclodextrins/*chemistry
EDAT- 2010/03/03 06:00
MHDA- 2010/09/09 06:00
CRDT- 2010/03/03 06:00
PHST- 2010/03/03 06:00 [entrez]
PHST- 2010/03/03 06:00 [pubmed]
PHST- 2010/09/09 06:00 [medline]
AID - 10.1021/la904788t [doi]
PST - ppublish
SO  - Langmuir. 2010 Jun 1;26(11):8971-80. doi: 10.1021/la904788t.