Circular polarization of fluorescence of chlorophyll in solution and in native structures

Gafni, Ari; Hardt, Haim; Schlessinger, Joseph; Steinberg, Izchak Z.

doi:10.1016/0005-2728(75)90108-5

Cited by 23 publications

(14 citation statements)

References 20 publications

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“…Therefore, rac-2 was converted into the corresponding menthylcarbonate by treatment with (¹)-menthyl chloroformate 13 to give a diastereomixture of 4 (dia-4) quantitatively. To our surprise, the diastereomers exhibited completely different properties as regards 1 H NMR signals (see SI) and retardation factors (R f -value) in SiO 2 thin layer chromatography (TLC), 0.38 and 0.27 (SiO 2 eluted with n-hexane/toluene = 1:1) (see SI). It should be mentioned that the corresponding behaviors of BINOL were not remarkable; for example, the R f -values of the corresponding diastereomers were identical under various conditions, and all of our separation attempts by column chromatography met with failure.…”

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confidence: 99%

“…Because of the high sensitivity of steady-state luminescence, CPL spectroscopy has attracted much attention, particularly in the analysis and evaluation of naturally occurring chiral chromophores, such as chlorophyll (vide infra). 1 Although CPL spectroscopy is a relatively new technique, a pioneering review was published as early as in 1977. 2 Currently, CPL is regarded as an important chiroptical technique.…”

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confidence: 99%

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π-Expanded Axially Chiral Biaryls and Their Emissions: Molecular Design, Syntheses, Optical Resolution, Absolute Configuration, and Circularly Polarized Luminescence of 1,1′-Bipyrene-2,2′-diols

et al. 2015

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Axially chiral biaryls based on pyrene, 1,1¤-bipyrene-2,2¤-diol derivatives 2, were designed and synthesized from 2-hydroxypyrene. Simple optical resolution was carried out and the absolute configuration was determined by diffraction study. Title compounds 2 and corresponding menthylcarbonate 4 showed clear circularly polarized luminescence (CPL) spectra. The degree of dimensionless Kuhn's anisotropy in the photoexcited state («g em «) of 2 and 4 were ca. 3.6 © 10 ¹4 and ca. 1.2 © 10 ¹3, respectively. Noteworthy properties were as follows: 1) high fluorescent quantum yields of 2 and 4, 0.57 and 0.80, respectively, in marked contrast to that of BINOL, 0.04 and 2) bathochromic shifts of CPL .Circularly polarized luminescence (CPL) is luminescence emitted by a chiral molecule. Because of the high sensitivity of steady-state luminescence, CPL spectroscopy has attracted much attention, particularly in the analysis and evaluation of naturally occurring chiral chromophores, such as chlorophyll (vide infra).1 Although CPL spectroscopy is a relatively new technique, a pioneering review was published as early as in 1977.2 Currently, CPL is regarded as an important chiroptical technique. The applications of CPL have shifted from the analytical chemistry of biological chiral molecules 2 to advanced science using polarized light, such as three-dimensional displays and quantum computing. 3CPL spectroscopy has flourished under the watch of physical chemists. However, the lack of a standard molecule having a large quantum yield (Φ fl ) and a large dimensionless Kuhn's anisotropy in the photoexcited state («g em «) (vide infra), 2 has hindered the development of new materials for CPL. Although 1,1¤-binaphthalen-2,2¤-diol (BINOL) 1 (Chart 1) and its corresponding derivatives are well used in this research field, Φ fl and g em are small (vide infra). In this study, our aim was to design a standard molecule for CPL spectroscopy. The expansion of the π-electronic system seemed to be the most promising strategy, i.e., replacement of the naphthalene moiety of BINOL with other π-expanded polycyclic aromatic hydrocarbons (PAHs). Generally, the expansion of the π-electronic system induces 1) a small HOMOLUMO gap and a resultant low excitation energy, 2) an increase in the fluorescence lifetime, 3) a low redox potential, and so on. 4 These properties are preferred for advanced materials. We focused on pyrene as PAH because it showed strong emission, long lifetime, and high quantum yield, making it one of the standard molecules for photochemistry. 5,6 We designed 1,1¤-bipyrene-2,2¤-diol 2, a pyrene-based axially chiral molecule, with a eye to improving the chiroptical properties of BINOLs.Optically pure title compounds 2 and reference 5 were prepared according to Scheme 1. 7 The issues to be addressed were 1) the solubility improvement of 2 and 2) optical resolution. PAHs are notorious for their poor solubilities and our targets 2, dimers of pyrene, ought to be sparingly soluble materials. To solve this problem, a tertbutyl group was intro...

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confidence: 99%

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confidence: 99%

π-Expanded Axially Chiral Biaryls and Their Emissions: Molecular Design, Syntheses, Optical Resolution, Absolute Configuration, and Circularly Polarized Luminescence of 1,1′-Bipyrene-2,2′-diols

et al. 2015

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“…The bell maximum (no minimum was reported) occurred in the temperature range of 40-45°C, closely resembling our CPL results. Gafni et al (1975) found a close correlation between the Hill reaction and CPL signals of isolated chloroplasts. Taken together with Mukohata's data, these previous findings solidly support our present results.…”

Section: Effect Of a 20fi65°c Thermal Impactmentioning

confidence: 64%

Left- and right-handed LHC II macroaggregates revealed by circularly polarized chlorophyll luminescence

et al. 2006

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Circularly polarized chlorophyll luminescence (CPL) may serve as a measure of chiral macroaggregates of the light-harvesting chlorophyll-protein complexes (LHC II) in both isolated chloroplasts and intact leaves (Gussakovsky et al (2000) Photosynth Res 65: 83-92). In the present work, we applied the CPL approach to study the effect of fast (1-2 min) thermal impacts on LHC II macroaggregates. The results revealed unexpected temperature-response kinetics, composed of initial bell-shaped changes in the CPL signal, followed by degradation down to a steady state (equilibrium). The bell-shape effect was dependent upon illumination, and vanished in the dark. A mathematical analysis of the temperature-response kinetics uniquely indicated that LHC II chiral macroaggregates may persist in both left- and right-handed forms. These forms differ in their response to high temperatures. Both forms are more thermostable in leaves than in isolated chloroplasts. The cooperative degradation of LHC II macroaggregates, which is induced by the thermal impact, is irreversible. It is therefore suggested that the native LHC II macroaggregates are stable, stationary, non-equilibrium, spatially heterogeneous (dissipative) structures. The dissipative properties probably allow the interconversion between left- and right-handed forms under perturbation by certain factors. Illumination probably serves as one such perturbation factor, initiating the interconversion of dark-adapted, left-handed to light-dependent, right-handed LHC II macroaggregates. The chiral heterogeneity of the LHC II macroaggregates is a newly revealed aspect which needs to be taken into consideration in future circular dichroism or CPL studies.

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“…Circularly polarized luminescence (CPL), i. e., light emission from a chiral molecule, is an old research topic that has continued to attract researchers because of the many new and exciting discoveries made . This phenomenon was discovered in the mid 1960s and chlorophyll was one of the first substrates to be measured . However, the unavailability of the CPL spectrophotometer had stunted the progress of this research topic although many applications to contemporary advanced materials had been proposed, e. g., three‐dimensional displays, quantum computing, security tags, and so on .…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Optical Resolution, and Circularly Polarized Luminescence of an Axially Chiral Porphyrin Dimer

et al. 2018

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Motivated by the chiral supramolecular structures of chlorophylls in photosynthesis proteins, i. e., special pairs present in purple photosynthetic bacteria, photosystems‐I, and ‐II, a chiral porphyrin dimer was designed, synthesized, and resolved to give optically pure forms. Synthesis of the dimer was achieved by using 5,10‐diarylporphyrin as the starting material. The stereochemistry of the dimer was speculated by comparing experimentally and theoretically obtained circular dichroism spectra. Clear circularly polarized luminescence spectra were obtained at 636 nm with dimensionless Kuhn's anisotropy value of ∼2.0 × 10−3.

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Circular polarization of fluorescence of chlorophyll in solution and in native structures

Cited by 23 publications

References 20 publications

π-Expanded Axially Chiral Biaryls and Their Emissions: Molecular Design, Syntheses, Optical Resolution, Absolute Configuration, and Circularly Polarized Luminescence of 1,1′-Bipyrene-2,2′-diols

π-Expanded Axially Chiral Biaryls and Their Emissions: Molecular Design, Syntheses, Optical Resolution, Absolute Configuration, and Circularly Polarized Luminescence of 1,1′-Bipyrene-2,2′-diols

Left- and right-handed LHC II macroaggregates revealed by circularly polarized chlorophyll luminescence

Synthesis, Optical Resolution, and Circularly Polarized Luminescence of an Axially Chiral Porphyrin Dimer

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