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Title: PhotochemCAD 3: Diverse Modules for Photophysical Calculations with Multiple Spectral Databases

 [1];  [1];  [1]
  1. Department of Chemistry, North Carolina State University, Raleigh NC
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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Photochemistry and Photobiology
Additional Journal Information:
Related Information: CHORUS Timestamp: 2018-02-12 13:33:34; Journal ID: ISSN 0031-8655
Country of Publication:
United Kingdom

Citation Formats

Taniguchi, Masahiko, Du, Hai, and Lindsey, Jonathan S. PhotochemCAD 3: Diverse Modules for Photophysical Calculations with Multiple Spectral Databases. United Kingdom: N. p., 2018. Web. doi:10.1111/php.12862.
Taniguchi, Masahiko, Du, Hai, & Lindsey, Jonathan S. PhotochemCAD 3: Diverse Modules for Photophysical Calculations with Multiple Spectral Databases. United Kingdom. doi:10.1111/php.12862.
Taniguchi, Masahiko, Du, Hai, and Lindsey, Jonathan S. 2018. "PhotochemCAD 3: Diverse Modules for Photophysical Calculations with Multiple Spectral Databases". United Kingdom. doi:10.1111/php.12862.
title = {PhotochemCAD 3: Diverse Modules for Photophysical Calculations with Multiple Spectral Databases},
author = {Taniguchi, Masahiko and Du, Hai and Lindsey, Jonathan S.},
abstractNote = {},
doi = {10.1111/php.12862},
journal = {Photochemistry and Photobiology},
number = ,
volume = ,
place = {United Kingdom},
year = 2018,
month = 2

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on February 12, 2019
Publisher's Accepted Manuscript

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  • Isoporphyrins are porphyrin tautomers with a saturated meso carbon and thus an interrupted {pi} system. We report here steady-state optical absorption, fluorescence, and fluorescence polarization data as well as time-resolved results that detail the significant effects of porphyrine tautomerization on the photophysical properties of a metallo-isoporphyrin, zinc 2,3,5,5{prime},7,8,12,18-octamethyl-13,17-bis(3-methoxy-3-oxop ropyl) isoporphyrin perchlorate (2). Besides the red-shifted, low-energy absorption bands diagnostic of metallo-isoporphyrins, 2 exhibits a large Stokes shift of its fluorescence emission (approximately 600 cm{sup {minus}1}) and an unusually short singlet excited-state lifetime at room temperature (130 {+-} 15 ps), photophysical properties distinctly different from those of the canonical prophyrin tautomers.more » The only porphyrins to exhibit marginally similar perturbations of their photophysical properties are those with severely nonplanar macrocyles whose {pi} systems are significantly destabilized by the conformational distortions and thus approach the interrupted {pi} systems of isoporphyrins. In addition to providing the first insights into the photophysical consequences of porphyrin tautomerization, the results for the isoporphyrin further document the sensitivity of the fundamental electronic and excited-state properties of porphyrinic chromophores to modulation of their {pi} systems in vitro and, by extrapolation, in vivo as well. 28 refs., 4 figs.« less
  • Photosystem II reaction center (RC) preparations isolated from spinach (Spinacea oleracea) by the Nanba-Satoh procedure are quite labile, even at 4{degree}C in the dark. Simple spectroscopic criteria were developed to characterize the native state of the material. Degradation of the RC results in (a) blue-shifting of the red-most absorption maximum, (b) a shift of the 77 K fluorescence maximum from {approximately}682 nm to {approximately}670 nm, and (c) a shift of fluorescence lifetime components from 1.3-4 nanoseconds and >25 nanoseconds to {approximately}6-7 nanoseconds. Fluorescence properties at 77 K seem to be a more sensitive spectral indicator of the integrity of themore » material. The >25 nanosecond lifetime component is assigned to P680{sup +} Phenophytin{sup -}recombination luminescence, which suggest a correlation between the observed spectral shifts and the photochemical competence of the preparation. Substitution of lauryl maltoside for Triton X-100 immediately after RC isolation stabilizes the RCs and suggests that Triton may be responsible for the instability.« less
  • Anthracene-2 sulfonate (2AS) molecules dimerized upon adsorption from aqueous solution onto positively charged alumina-coated silica particles (25-nm diameter). This ground-state dimerization was accompanied by an intensification and red-shift (from 370 to 401 nm) of the O-O absorption band and a large decrease in fluorescence quantum yield. Anthracene-1,5-disulfonate (1,5AS) and anthracene-1-sulfonate molecules also adsorbed to the particles but did not dimerize. Triplet states of the adsorbed molecules were characterized by laser flash photolysis. Direct photoexcitation of the 2AS dimer failed to produce an observable triplet state, but photosensitization yielded a triplet state of the dimer resembling that of the monomer. Themore » triplet state of the adsorbed 1,5AS molecule was obtained by either direct or sensitized excitation. Binding capacities of the particles for 2AS and 1,5AS indicated that at maximal coverage the 2AS molecules were tilted with respect to the surface while the 1,5AS molecules were coplanar. Dimerization of 2AS occurred even when fewer than 1% of available adsorption sites were occupied.« less
  • The room-temperature luminescence and photophysics of a series of early transition metal, first-row organometallic complexes with the general formula Cp*[sub 2]ScX (where Cp* is [eta][sub 5]-C[sub 5](CH[sub 3])[sub 5][sup [minus]] and X represents a [sigma]-donating ligand) are reported. Semiempirical molecular orbital calculations using the INDO/S method (ZINDO) have been performed. The calculations were carried out using full C[sub 5](CH[sub 3])[sub 5]- ligands for Cp*[sub 2]ScX, X = Cl, I, CH[sub 3]. The calculations indicate a large amount of metal and ligand orbital mixing in these d[sup 0] complexes, with the lowest unoccupied molecular orbitals consisting principally of Sc d-orbitals admixingmore » with Cp* [pi]-orbitals. The highest-occupied molecular orbital for the chloride derivative contains primarily Cp* character, while that of the iodide species is mostly halogen in nature. The presence of a lone pair on X is requisite for room-temperature emission to occur, as evidenced by the observation of luminescence for X = Cl[sup [minus]], I[sup [minus]], and NHPh and by the lack of luminescence Cp*[sub 2]ScCH[sub 3] or Cp*[sub 2]ScCH[sub 2]Ph, under identifical conditions. 21 refs., 5 figs., 4 tabs.« less