21414-81-3Relevant academic research and scientific papers
Quantitative cavities and reactivity in stages of crystal lattices: Mechanistic and exploratory organic photochemistry
Zimmerman, Howard E.,Nesterov, Evgueni E.
, p. 2818 - 2830 (2007/10/03)
In continuing our research on solid-state organic photochemistry, we have been investigating the phenomenon of reactivity in stages. In this study we present new examples where the photochemical reactivity changes discontinuously at some point in the conversion. In these instances, the reaction course of the solid differs from that in solution. One example is the reaction of 2-methyl-4,4-diphenylcyclohexenone, where an unusual reaction course was encountered in the solid state; and, of two possible mechanisms, one was established by isotopic labeling. A second case is that of 4,5,5-triphenylcyclohexenone. The solid-state reaction of this enone was found to give a new photochemical transformation, the Type C rearrangement, a process that involves a δ to α aryl migration. In the case of 3-tert-butyl-5,5-diphenylcyclohexenone the Type C rearrangement occurred even in solution. The stage behavior was investigated using X-ray analysis and Quantum Mechanics/Molecular Mechanics computations. This permitted us to determine the sources and details of the stage phenomenon. The analysis revealed how a product molecule as a neighbor affects reactivity. The computations were employed to follow the course of a solid-state reaction from reactant through the succeeding stages. Additionally, the Delta-Density Analysis was utilized to ascertain the electronic nature of molecular changes. Besides product composition changing with extent of conversion, the reaction quantum yield was found to change as one stage gave way to a succeeding one.
General theoretical treatments of solid-state photochemical rearrangements and a variety of contrasting crystal versus solution photochemistry
Zimmerman, Howard E.,Zhu, Zhaoning
, p. 5245 - 5262 (2007/10/02)
In continuing our investigations of control of excited state reactivity by inclusion in crystal lattices, we have encountered a variety of new examples of differing reactivity resulting from lattice restraints. Different theoretical treatments were tested
Photochemistry of some allenic counterparts of cyclohexenones and 2,5-cyclohexadienones
Zimmerman, Howard E.,Baker, Mark R.,Bottner, Robert C.,Morrissey, Michael M.,Murphy, Sean
, p. 459 - 466 (2007/10/02)
Allenic analogs of 4,4-diphenylcycIohexenone and a similar counterpart of 4,4-diphenyl-2,5-cyclohexadienone were synthesized. These molecules have a 2-electron π-MO perpendicular to the six-ring π-system. This perpendicular π-orbital is analogous to the oxygen py orbital which is orthogonal to the carbonyl π-bond. The photochemistry of the allenic systems was explored with the finding that the triplets were unreactive and the singlets underwent a phenyl migration to form bicyclic photoproducts whose structures were established by spectral means, degradation, and independent synthesis. Excited states involving appreciable out-of-plane to π or π to out-of-plane excitations are defined as π- * and -π*, respectively. MNDO-CI level and CASSCF ab initio computations with geometry optimization were carried out with the objective of determining the role of -π* and π-* transitions and for comparison with the experimental results.
Photochemistry in a Box. Photochemical Reactions of Molecules Entrapped in Crystal Lattices: Mechanistic and Exploratory Organic Photochemistry
Zimmerman, Howard E.,Zuraw, Michael J.
, p. 7974 - 7989 (2007/10/02)
An exploration was made of the photochemical behavior in the crystalline state of a series of molecules we have previously studied in solution.The reactions studied fall into the categories of cyclohexenone rearrangements, reactions of di-?-methane system
Photochemical Rearrangements of Molecules Having Quenchers on a Chain. Mechanistic and Exploratory Organic Photochemistry
Zimmerman, Howard E.,Weber, Andrew M.
, p. 995 - 1007 (2007/10/02)
The photochemistry of 4,4-diphenylcyclohexenones bearing substituents at C-6 was investigated.The C-6 substituents utilized were 4-(β-naphthyl)butyl, β-naphthylmethyl, biphenylylmethyl, methyl, and propyl.There was an interesting kinetic preference for fo
