scholarly journals Uncovering dark multichromophoric states in Peridinin–Chlorophyll–Protein

2020 ◽  
Vol 17 (164) ◽  
pp. 20190736
Author(s):  
Elliot J. Taffet ◽  
Francesca Fassioli ◽  
Zi S. D. Toa ◽  
David Beljonne ◽  
Gregory D. Scholes
Keyword(s):  
Crystal Structure ◽  
Excited States ◽  
Quantum Chemical ◽  
Light Harvesting ◽  
Singlet Fission ◽  
Chlorophyll Protein ◽  
Triplet Pair ◽  
A Charge ◽  
Hole Generation ◽  
Chemical Evidence

It has long been recognized that visible light harvesting in Peridinin–Chlorophyll–Protein is driven by the interplay between the bright (S 2 ) and dark (S 1 ) states of peridinin (carotenoid), along with the lowest-lying bright (Q y ) and dark (Q x ) states of chlorophyll- a . Here, we analyse a chromophore cluster in the crystal structure of Peridinin–Chlorophyll–Protein, in particular, a peridinin–peridinin and a peridinin–chlorophyll- a dimer, and present quantum chemical evidence for excited states that exist beyond the confines of single peridinin and chlorophyll chromophores. These dark multichromophoric states, emanating from the intermolecular packing native to Peridinin–Chlorophyll–Protein, include a correlated triplet pair comprising neighbouring peridinin excitations and a charge-transfer interaction between peridinin and the adjacent chlorophyll- a . We surmise that such dark multichromophoric states may explain two spectral mysteries in light-harvesting pigments: the sub-200-fs singlet fission observed in carotenoid aggregates, and the sub-200-fs chlorophyll- a hole generation in Peridinin–Chlorophyll–Protein.

Unconventional singlet fission materials

2021 ◽  
Author(s):  
Tobias Ullrich ◽  
Dominik Munz ◽  
Dirk M. Guldi
Keyword(s):  
Excited States ◽  
Singlet Fission ◽  
Triplet Excited States

Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states.

On tungstates of divalent cations (III) – Pb5O2[WO6]

2020 ◽  
Vol 235 (8-9) ◽  
pp. 311-317
Author(s):  
Stephan G. Jantz ◽  
Florian Pielnhofer ◽  
Henning A. Höppe
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Quantum Chemical ◽  
Density Functional ◽  
Divalent Cations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
First Results ◽  
Electrostatic Calculations

Abstract${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ was discovered as a frequently observed side phase during our investigation on lead tungstates. Its crystal structure was solved by single-crystal X-ray diffraction ($P{2}_{1}/n$, $a=7.4379\left(2\right)$ Å, $b=12.1115\left(4\right)$ Å, $c=10.6171\left(3\right)$ Å, $\beta =90.6847\left(8\right)$°, $Z=4$, ${R}_{\text{int}}=0.038$, ${R}_{1}=0.020$, $\omega {R}_{2}=0.029$, 4188 data, 128 param.) and is isotypic with ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{Te}}_{6}\right]$. ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ comprises a layered structure built up by non-condensed [WO6]${}^{6-}$ octahedra and ${\left[{\text{O}}_{4}{\text{Pb}}_{10}\right]}^{12+}$ oligomers. The compound was characterised by spectroscopic measurements (Infrared (IR), Raman and Ultraviolet–visible (UV/Vis) spectra) as well as quantum chemical and electrostatic calculations (density functional theory (DFT), MAPLE) yielding a band gap of 2.9 eV fitting well with the optical one of 2.8 eV. An estimation of the refractive index based on the Gladstone-Dale relationship yielded $n\approx 2.31$. Furthermore first results of the thermal analysis are presented.

Crystal Structure of Archaeal Photolyase from Sulfolobus tokodaii with Two FAD Molecules: Implication of a Novel Light-harvesting Cofactor

2007 ◽  
Vol 365 (4) ◽  
pp. 903-910 ◽  
Author(s):  
Masahiro Fujihashi ◽  
Nobutaka Numoto ◽  
Yukiko Kobayashi ◽  
Akira Mizushima ◽  
Masanari Tsujimura ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Light Harvesting ◽  
Sulfolobus Tokodaii

Modulated vacancy ordering in SrGe6−x (x≈0.45)

2019 ◽  
Vol 74 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Ulrich Schwarz ◽  
Rodrigo Castillo ◽  
Aron Wosylus ◽  
Lev Akselrud ◽  
Yurii Prots ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ambient Pressure ◽  
Stoichiometric Composition ◽  
Binary Compound ◽  
Crystal Structure Analysis ◽  
Local Defect ◽  
X Ray Diffraction ◽  
Vacancy Ordering ◽  
Metal Type ◽  
A Charge

AbstractThe structural properties of modulated SrGe6−x (x≈0.45) were investigated by means of single-crystal and powder X-ray diffraction combined with quantum chemical calculations. The framework compound SrGe6−x adopts a defect variant of the EuGa2Ge4-type crystal structure. Samples of the binary compound with nominal compositions 0≤x≤0.5 were synthesized at pressures from 5 to 6 GPa and a temperature of typically 1400 K. The product reveals diffraction peaks of the EuGa2Ge4-type subcell plus additional reflections indicating an ordered superstructure. Detailed crystal structure analysis evidences the incommensurate nature of the superstructure and a modulation of the vacancy ordering in the germanium network. The computations have shown that the non-stoichiometric composition of the framework with its local defect organization affects the calculated charge of the strontium anions. Although the chemical composition is close to a charge-balanced situation, temperature-dependent resistivity measurements showed metal-type conductivity. At ambient pressure SrGe6−x decomposes exothermally and irreversibly at T=680(10) K into SrGe2 and germanium, indicating its metastable nature at ambient pressure.

Preparation, crystal structure and quantum chemical investigation of [Li(NTO) (H2O)]

1999 ◽  
Vol 44 (3) ◽  
pp. 214-218 ◽  
Author(s):  
Jirong Song ◽  
Zhaoxu Chen ◽  
Heming Xiao ◽  
Rongzu Hu ◽  
Fuping Li
Keyword(s):  
Crystal Structure ◽  
Quantum Chemical ◽  
Chemical Investigation ◽  
Quantum Chemical Investigation
Sign in / Sign up

Export Citation Format

Share Document