127464-92-0Relevant articles and documents
Templation of the excited-state chemistry of α-(n-alkyl) dibenzyl ketones: how guest packing within a nanoscale supramolecular capsule influences photochemistry
Gibb, Corinne L. D.,Sundaresan, Arun Kumar,Ramamurthy,Gibb, Bruce C.
, p. 4069 - 4080 (2008/12/20)
Excited-state behavior of eight α-alkyl dibenzyl ketones (alkyl = CH3 through n-C8H17) that are capable of undergoing type II and/or type I photoreactions has been explored in isotropic solution and within a water-soluble capsule. The study consisted of two parts: photochemistry that explored the excited-state chemistry and an NMR analysis that revealed the packing of each guest within the capsule. The NMR data (COSY, NOESY, and TOCSY experiments) revealed that ternary complexes between α-alkyl dibenzyl ketones and the capsule formed by two cavitands are kinetically stable, and the guests fall into three packing motifs modulated by the length of the α-alkyl chain. In essence, the host is acting as an external template to promote the formation of distinct guest conformers. The major products from all eight guests upon irradiation either in hexane or in buffer solution resulted from the well-known Norrish type I reaction. However, within the capsule the excited-state chemistry of the eight ketones was dependent on the alkyl chain length. The first group consisted of α-hexyl, α-heptyl, and α-octyl dibenzyl ketones that yielded large amounts of Norrish type II products within the host, while in solution the major products were from Norrish type I reaction. The second group consists of α-butyl and α-pentyl dibenzyl ketones that yield equimolar amounts of two rearranged starting ketones within the capsule (combined yield of ca 60%), while in solution no such products were formed. The third group consisted of α-methyl, α-ethyl, and α-propyl dibenzyl ketones that within the capsule yielded only one (not two) rearranged starting ketone in larger amounts (21-35%) while in solution no rearrangement product was obtained. Variation in the photochemistry of the guest within the capsule, with respect to the α-alkyl chain length of the guest, highlights the importance of how a small variation in supramolecular structure can influence the selectivity within a confined nanoscale reactor.
Norrish Type I and Type II Reactions of Ketones as Photochemical Probes of the Interior of Zeolites
Ramamurthy, V.,Corbin, D. R.,Eaton, D. F.
, p. 5269 - 5278 (2007/10/02)
The Norrish type I and type II reactions of alkylbenzoin ethers, alkyldeoxybenzoins and α-alkyldibenzyl ketones included within the microporous structures of zeolites X and Y have been investigated.Product distributions varied significantly from that observed in benzene.In addition, it differed between various alkali-metal cation-exchanged samples.These variations are interpreted to result from the restriction offered by the zeolite micropores on the motions of the adsorbed organic molecule.Although this study is restricted to ketones, the knowledge gained is expected to be of general value.
Modification of Photochemical Reactivity by Cyclodextrin Complexation: A Remarkable Effect on the Photobehavior of α-Alkyldibenzyl Ketones
Nageshwer Rao, B.,Syamala, M. S.,Turro, N. J.,Ramamurthy, V.
, p. 5517 - 5521 (2007/10/02)
The Norrish type I and type II reactions of cyclodextrin-included α-alkyldibenzyl ketones have been investigated in the aqueous solution and in the solid state.The photolysis of solid cyclodextrin complexes led to a single product, diphenylethane (AB), and that of complexes in the aqueous solution resulted in a product arising from the rerrangement of α-alkyldibenzyl ketones.Conformational and super-cage effects are proposed to be responsible for the dramatic alteration observed in the above photobehavior.The difference in the product distribution between solid and solution complexes is attributed to the differences in the restriction imposed by the host on the translational motions of the geminate radical pairs.
