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Mereshchenko_PhD_final.pdf (3.47 MB)
ETD Abstract Container
Abstract Header
ULTRAFAST PHOTOCHEMISTRY OF POLYATOMIC MOLECULES CONTAINING LABILE HALOGEN ATOMS IN SOLUTION
Author Info
Mereshchenko, Andrey S
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1369774991
Abstract Details
Year and Degree
2013, Doctor of Philosophy (Ph.D.), Bowling Green State University, Photochemical Sciences.
Abstract
Because breaking and making of chemical bonds lies at the heart of chemistry, this thesis focuses on dynamic studies of labile molecules in solutions using ultrafast transient absorption spectroscopy. Specifically, my interest is two-fold: (i) novel reaction intermediates of polyhalogenated carbon, boron and phosphorus compounds; (ii) photophysics and photochemistry of labile copper(II) halide complexes. Excitation of CH
2
Br
2
, CHBr
3
, BBr
3
, and PBr
3
into n(Br)σ*(X-Br) states, where X=C, B, or P, leads to direct photoisomerization with formation of isomers having Br-Br bonds as well as rupture of one of X-Br bonds with the formation of a Br atom and a polyatomic radical fragment, which subsequently recombine to form similar isomer products. Nonpolar solvation stabilizes the isomers, consistent with intrinsic reaction coordinate calculations of the isomer ground state potential energy surfaces at the density functional level of theory, and consequently, the involvement of these highly energetic species on chemically-relevant time scales needs to be taken into account. Monochlorocomplexes in methanol solutions promoted to the ligand-to-metal charge transfer (LMCT) excited state predominantly undergo internal conversion via back electron transfer, giving rise to vibrationally hot ground-state parent complexes. Copper-chloride homolitical bond dissociation yielding the solvated copper(I) and Cl- atom/solvent CT complexes constitutes a minor pathway. Insights into ligand substitution mechanisms were acquired by monitoring the recovery of monochloro complexes at the expense of two unexcited dichloro- and unsubstituted forms of Cu(II) complexes also present in the solution. Detailed description of ultrafast excited-state dynamics of CuCl
4
2-
complexes in acetonitrile upon excitation into all possible Ligand Field (LF) excited states and two most intense LMCT transitions is reported. The LF states were found to be nonreactive with lifetimes remarkably longer than those for copper(II) complexes studied so far, in particular, copper blue proteins. The highest
2
A
1
and lowest
2
E LF states relax directly to the ground electronic state whereas the intermediate
2
B
1
LF state relaxes stepwise through the
2
E state. The LMCT excited states are short-lived undergoing either ionic dissociation (CuCl
3
-
+ Cl
-
) or cascading relaxation through the manifold of vibrationally hot LF states to the ground state.
Committee
Alexander Tarnovsky (Advisor)
H. Peter Lu (Committee Member)
John Cable (Committee Member)
Donald Deters (Committee Member)
Pages
254 p.
Subject Headings
Chemistry
;
Physical Chemistry
;
Physics
Keywords
Pump-probe
;
bromoform
;
dibromomethane
;
boron bromide
;
phosphorous(III) bromide
;
copper(II)
;
chlorocomplexes
;
chloride
;
CH2Br2
;
CHBr3
;
PBr3
;
BBr3
;
CuCl+
;
CuCl4
;
ultrafast
;
dynamics
;
femtosecond
;
time-resolved
;
strong coupling limit
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Citations
Mereshchenko, A. S. (2013).
ULTRAFAST PHOTOCHEMISTRY OF POLYATOMIC MOLECULES CONTAINING LABILE HALOGEN ATOMS IN SOLUTION
[Doctoral dissertation, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1369774991
APA Style (7th edition)
Mereshchenko, Andrey.
ULTRAFAST PHOTOCHEMISTRY OF POLYATOMIC MOLECULES CONTAINING LABILE HALOGEN ATOMS IN SOLUTION.
2013. Bowling Green State University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1369774991.
MLA Style (8th edition)
Mereshchenko, Andrey. "ULTRAFAST PHOTOCHEMISTRY OF POLYATOMIC MOLECULES CONTAINING LABILE HALOGEN ATOMS IN SOLUTION." Doctoral dissertation, Bowling Green State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1369774991
Chicago Manual of Style (17th edition)
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Document number:
bgsu1369774991
Download Count:
1,460
Copyright Info
© 2013, some rights reserved.
ULTRAFAST PHOTOCHEMISTRY OF POLYATOMIC MOLECULES CONTAINING LABILE HALOGEN ATOMS IN SOLUTION by Andrey S Mereshchenko is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Bowling Green State University and OhioLINK.