The n-π* Absorption and Emission of Optically Active <i>trans-β</i>-Hydrindanone and <i>trans-β</i>-Thiohydrindanone

Emeis, C.A.; Oosterhoff, L.J.

doi:10.1063/1.1674756

Cited by 65 publications

(46 citation statements)

References 22 publications

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“…In these experiments, the separated enantiomers of trans-β-hydrindanone and trans-β-thiohydrindanone were investigated, with results demonstrating the potential utility of CPL as a structural probe of emissive states. 15 Subsequent studies have demonstrated the observation of CPL for a variety of chiral molecules in solution, including organic systems, biomolecules and inorganic metal complexes. 16 Generally speaking, it is apparent from the literature that CPL phenomena are best exemplified by chiral lanthanide complexes.…”

Section: Systems Exhibiting Cplmentioning

confidence: 99%

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

2012

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any wayThe full-text must not be sold in any format or medium without the formal permission of the copyright holders. Statement of CopyrightThe copyright of this thesis rests with the author. No quotations should be published without prior consent and information derived from it must be acknowledged. ABSTRACT -ii - ABSTRACTA series of studies has been undertaken to facilitate the identification and development of chiral lanthanide complexes that are able to report on changes in their local environment through modulation of the circular polarization of their emission. Reports of such systems remain relatively rare in the literature, notwithstanding the prevalence and importance of chirality in biological systems.The work described herein is separated into five chapters, the first of which comprises a discussion of relevant background information, along with a comprehensive review of responsive lanthanide-based CPL probes reported to date. A classification of these probes is built up, which informs the content of the following three chapters.Chapter 2 describes work undertaken in the pursuit of a novel lanthanide-based system for use as a CPL probe for the detection of proteins. The synthesis of an enantiopure lanthanide complex was undertaken and characterisation of this system carried out with reference to a structurally related racemic complex. A series of comparative investigations designed to probe the relative protein binding capability of these complexes was subsequently performed, which revealed that the observation of induced CPL from racemic lanthanide systems may be brought about by a change in complex constitution. This is the first example of such an effect from a well-defined racemic lanthanide complex in solution. Chapter 3 goes on to detail studies undertaken to demonstrate the utility of this racemic lanthanide system as a probe for chiral detection.Chapter 4 describes investigations carried out in an attempt to identify new systems exhibiting chiral quenching effects in solution. Initially, two pairs of enantiomeric electron-rich quenching species were assessed for their ability to quench the emission from an enantiopure DOTA-derived lanthanide complex differentially. Subsequently, investigations were focussed on examining the quenching of emission from novel enantiopure lanthanide complexes based on a 1,4,7-triazacyclononane framework, using cobalt complexes as the quenching species.Finally, Chapter 5 contains experimental procedures for each compound synthesised, as well as general experimental procedures.

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Section: Systems Exhibiting Cplmentioning

confidence: 99%

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

2012

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“…The circular polarization of luminescence (CPL) of a chromophore is the emission analog of circular dichroism, and is related to the conformation of the electronically excited chromophore in the same way that circular dichroism is related to the conformation of the chromophore in the ground state (7)(8)(9)(10)(11)(12)(13). CPL is thus a manifestation of the chirality, or asymmetry, of the molecule in addition to circular dichroism and optical rotatory dispersion.…”

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Antigen-induced conformational changes in antibodies and their Fab fragments studied by circular polarization of fluorescence.

Schlessinger¹,

Steinberg²,

Hochman³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

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Conformational changes induced in antibody molecules and in their Fab fragments by binding of antigen were investigated by the circular polarization of the fluorescence emitted by the tryptophan residues. This property of the fluorescence is related to the asymmetry, and thus to the conformation and environment, of the emitting chromophore. Changes in the circular polarization of the fluorescence of the antibody were observed upon binding of RNase to anti-RNase, of poly(DL-alanyl)-poly(L-lysine) to antipoly(D-alanine), and of the "loop" of lysozyme, a monovalent antigenic determinant, to anti-"loop." The spectral changes were observed at different antigen-antibody ratios, including high antigen excess, indicating that they are due to antigen binding and not to aggregation. We would like to understand how antigens trigger these events, and whether a "signal" is transmitted from the Fv to the Fc region within the antibody molecule. The structural expression of such a "signal" will presumably be an antigeninduced conformational change in the Fab, which will affect the Fc fragment. It is desirable to find a method that will resolve the changes in these portions of the antibody.Various attempts to demonstrate such conformational changes [see Metzger (1) for a review] have not yielded unequivocal conclusions, although some of these studies have indicated changes in the flexibility of the molecule (2), its sedimentation coefficient (3), or its volume (4), as a consequence of hapten binding. Other studies, using optical methods such as absorption, fluorescence, and circular dichroism clearly demonstrated changes in the antibody molecules that take place upon binding of hapten, but could be interpreted as changes in the combining site or in its vicinity (5, 6). In this study we have investigated the conformational changes that take place in antibody molecules upon binding of antigens or hapten by the circular polarization of the tryptophan fluorescence of the antibodies because this spectroscopic technique has some pronounced merits.The circular polarization of luminescence (CPL) of a chromophore is the emission analog of circular dichroism, and is related to the conformation of the electronically excited chromophore in the same way that circular dichroism is related to the conformation of the chromophore in the ground state (7-13). CPL is thus a manifestation of the chirality, or asymmetry, of the molecule in addition to circular dichroism and optical rotatory dispersion. CPL has a pronounced advantage over the other two spectroscopic techniques mentioned, i.e., the advantage of specificity when one studies complex systems. This is because only luminescent chromophores contribute to the CPL of the system, whereas, circular dichroism and optical rotatory dispersion are affected by all chromophores present. In the case of proteins, CPL probes only the region of those tryptophan, and to some extent tyrosine, residues that are both fluorescent and are situated in an asymmetric environment when they are in their elec...

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“…2 is a reflection of the asymmetry induced in the TNS chromophore by the protein environment when the dye is in the excited state. If the conformation and environment of the chromophore in the excited state are the same as those in the ground state, and if the absorption and emission processes involve exactly the same pairs of quantum states, the emission anisotropy factor, ge, should be of the same sign and magnitude as the absorption anisotropy factor, ga (7,8,14). Obviously, the value of ge obtained for the chymotrypsin-TNS complex is markedly smaller, by about a factor of 10, than the value of gp obtained for this complex.…”

Section: Resultsmentioning

confidence: 99%

“…An absorption band is circularly dichroic if the relevant excitation involves both an electric and a magnetic transition dipole moment and if the two transition moments are not orthogonal in space (7). Analogously, when the above conditions are fulfilled for a radiative transition from an excited state to the ground state, i.e., in luminescence, the light emitted by the luminescent molecules in solution will be partly circularly polarized (7,8). If the absorption and emission processes involve exactly the same pairs of quantum states, the extent of circular dichroism (CD) and the degree of circular polarization of the luminescence are related to each other by a simple expression (see below).…”

mentioning

confidence: 99%

Circular Polarization of Fluorescence of Probes Bound to Chymotrypsin. Change in Asymmetric Environment upon Electronic Excitation

Schlessinger

Steinberg

1972

Proc. Natl. Acad. Sci. U.S.A.

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The circular polarization of fluorescence is related to the conformational asymmetry of the emitting molecule in the first singlet excited state in the same way that circular dichroism is related to the conformational asymmetry of the absorbing molecule in the electronic ground state. By measurement of these optical phenomena, the induced asymmetry of two chromophores bound to chymotrypsin (EC 3.4.4.5) when in the ground state Was compared with the induced asymmetry of the ligands when in the excited state. The two chromophores studied were 2-p-toluidinylnaphthalene-6.sulfonate (TNS), bound at a specific site which is not the active site of the protein, and an anthraniloyl group, bound at the active site of the enzyme. Both chromophores showed a change in induced asymmetry upon electronic excitation, the effect being particularly large in the case of the TNS chromophore. It is thus concluded that the orientation of TNS in the binding site, its freedom of rotation in its site, the strength of binding, or even the site of binding of the dye to the protein might have changed upon electronic excitation.

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The n-π* Absorption and Emission of Optically Active trans-β-Hydrindanone and trans-β-Thiohydrindanone

Cited by 65 publications

References 22 publications

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

Antigen-induced conformational changes in antibodies and their Fab fragments studied by circular polarization of fluorescence.

Circular Polarization of Fluorescence of Probes Bound to Chymotrypsin. Change in Asymmetric Environment upon Electronic Excitation

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