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Dive into the research topics where Laura D. Shirtcliff is active.

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Featured researches published by Laura D. Shirtcliff.


Journal of Physical Chemistry A | 2011

Two-Photon Absorption Properties of Two-Dimensional π-Conjugated Chromophores: Combined Experimental and Theoretical Study

Koji Ohta; Satoru Yamada; Kenji Kamada; Aaron D. Slepkov; Frank A. Hegmann; Rik R. Tykwinski; Laura D. Shirtcliff; Michael M. Haley; Paweł Sałek; Faris Gel’mukhanov; Hans Ågren

The two-photon absorption (TPA) properties of four TPEB [tetrakis(phenylethynyl)benzene] derivatives (TD, para, ortho, and meta) with different donor/acceptor substitution patterns have been investigated experimentally by the femtosecond open-aperture Z-scan method and theoretically by the time-dependent density-functional theory (TDDFT) method. The four compounds show relatively large TPA cross sections, and the all-donor substituted species (TD) displays the largest TPA cross-section σ(2) = 520 ± 30 GM. On the basis of the calculated electronic structure, TD shows no TPA band in the lower energy region of the spectrum because the transition density is concentrated on particular transitions due to the high symmetry of the molecular structure. The centrosymmetric donor-acceptor TPEB para shows excitations resulting from transitions centered on D-π-D and A-π-A moieties, as well as transition between the D-π-D and A-π-A moieties; this accounts for the broad nature of the TPA bands for this compound. Calculations for two noncentrosymmetric TPEBs (ortho and meta) reveal that the diminished TPA intensities of higher-energy bands result from destructive interference between the dipolar and three-state terms. The molecular orbitals (MOs) of the TPEBs are derivable with linear combinations of the MOs of the two crossing BPEB [bis(phenylethynyl)benzene] derivatives. Overall, the characteristics of the experimental spectra are well-described based on the theoretical analysis.


Journal of Organic Chemistry | 2008

Computational analysis on the dual reactivity of conjugated "ene-ene-yne" systems.

Sean P. McClintock; Laura D. Shirtcliff; Rainer Herges; Michael M. Haley

The design of new reactions that yield benzo-fused five- or six-membered rings arising from conjugated ene-ene-yne precursors was examined computationally. Inclusion of heteroatoms (particularly N) in the bond making position was shown to lower activation energies due to participation of the lone pair electrons in the cyclization reactions. By systematically varying the atomic configuration in the ene-ene-yne system, the influence of heteroatoms was used to identify optimal candidates for future experimental study.


Proceedings of SPIE | 2005

The effects of donor-acceptor substitution symmetry on the nonlinear absorption of two-dimensionally-conjugated isomeric chromophores

Aaron D. Slepkov; Jeremiah A. Marsden; Jeremie J. Miller; Laura D. Shirtcliff; Michael M. Haley; Kenji Kamada; Rik R. Tykwinski; Frank A. Hegmann

Differential optical Kerr effect (DOKE) detection is a powerful tool for studying the ultrafast time-resolved dynamics of 3rd-order nonlinear processes. In this study, DOKE was used to measure the nonlinear absorption properties of tetraethynylphenylene (TEP) solutions in THF using 800 nm, 80 fs laser pulses. These two-dimensional, highly-conjugated chromophores (also known as TPEBs) show high instantaneous two-photon absorption (TPA) for relatively small chromophores. The TPA cross section is strongly dependent on the donor-acceptor geometry in these materials: a quadrupolar, all-donor TEP shows the smallest TPA, with a cross-section of σ(2)= 90 ± 15 GM. ortho-TEP, for which the donors (and acceptors) are conjugated via the ortho position across the central phenyl ring, is dipolar and displays the largest cross-section, of σ(2)= 260 ± 30 GM. para-TEP, which is quadrupolar, and meta-TEP, which is dipolar, display similar cross-sections of σ(2)= 160 ± 10 GM and σ(2)= 150 ± 10 GM, respectively. In addition to an instantaneous TPA response, these isomers show unique two-photon assisted excited-state absorption (ESA), with the ortho- and meta-TEP displaying a clear 3-10 ps rise to an ESA peak, and subsequent decay. The differences in the nonlinear absorption behaviour of these materials may be partially explained by selection rules and UV-vis spectroscopy. In addition, the polar geometries, coupled to the various in-plane conjugation paths, may further influence their optical nonlinearities. Understanding these trends impacts both the design of materials with desirable nonlinear absorption properties and our understanding of the electronic landscape in functionalized organic materials.


Journal of the American Chemical Society | 2005

Structure−Property Relationships of Donor/Acceptor-Functionalized Tetrakis(phenylethynyl)benzenes and Bis(dehydrobenzoannuleno)benzenes

Jeremiah A. Marsden; Jeremie J. Miller; Laura D. Shirtcliff; Michael M. Haley


Journal of Organic Chemistry | 2007

Systematic structure-property investigations and ion-sensing studies of pyridine-derivatized donor/acceptor tetrakis(arylethynyl)benzenes

Eric L. Spitler; Laura D. Shirtcliff; Michael M. Haley


Journal of Organic Chemistry | 2004

Experimental and Theoretical Investigation of the Coarctate Cyclization of (2-Ethynylphenyl)phenyldiazenes‡

Laura D. Shirtcliff; Timothy J. R. Weakley; Michael M. Haley; Felix Köhler; Rainer Herges


Journal of the American Chemical Society | 2006

Biscyclization reactions in butadiyne- and ethyne-linked triazenes and diazenes: concerted versus stepwise coarctate cyclizations.

Laura D. Shirtcliff; Austin G. Hayes; Michael M. Haley; Felix Köhler; Kirsten Hess; Rainer Herges


Chemical Society Reviews | 2008

Reactions in the conjugated ‘ene–ene–yne’ manifold: five-membered ring fragmentation and ring formation via coarctate/pseudocoarctate mechanisms

Laura D. Shirtcliff; Sean P. McClintock; Michael M. Haley


Journal of Organic Chemistry | 2006

Synthesis of 2H-indazoles via Lewis acid promoted cyclization of 2-(phenylazo)benzonitriles.

Laura D. Shirtcliff; Jazmin Rivers; Michael M. Haley


Journal of Organic Chemistry | 2007

CuCl-induced formation and migration of isoindazolyl carbenoids.

Laura D. Shirtcliff; Michael M. Haley; Rainer Herges

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Kenji Kamada

National Institute of Advanced Industrial Science and Technology

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