Microscopic chiral pockets in a tris(chelated) iridium(iii) complex as sites for dynamic enantioselective quenchingElectronic supplementary information (ESI) available: CD spectra of the enantiomers of [Ir(bzq)2(phen)]+; adsorption behaviour of Ir(iii) by clay minerals; quantum yield of Ir(iii) in various solvents; emission spectra of Ir(iii) in clay suspensions; stereochemical effects of emission from Ir(iii) adsorbed by SAP; enhancement of the luminescent quantum yield of [Ir(bzq)2(phen)]+ ads
An attempt to develop a chiral luminescent probe with enantioselectivity is described. A tris(chelated) iridium( iii ) complex with bulky ligands, [Ir(bzq) 2 (phen)] + (bzqH = benzo[ h ]quinoline; phen = 1,10-phenanthroline), was synthesized and optically resolved into Δ- and Λ-enantiomers. The comp...
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Main Authors | , , , , |
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Format | Journal Article |
Language | English |
Published |
26.03.2018
|
Online Access | Get full text |
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Summary: | An attempt to develop a chiral luminescent probe with enantioselectivity is described. A tris(chelated) iridium(
iii
) complex with bulky ligands, [Ir(bzq)
2
(phen)]
+
(bzqH = benzo[
h
]quinoline; phen = 1,10-phenanthroline), was synthesized and optically resolved into Δ- and Λ-enantiomers. The complex (denoted as Ir(
iii
)) was emissive in non-polar organic solvents, while in aprotic and protic polar solvents it was less emissive. When Ir(
iii
) was adsorbed by the colloidal particles of synthetic saponite (denoted as SAP), it recovered its emitting capability even in a solvent containing water. Emission from Ir(
iii
) adsorbed by SAP was quenched by adding [Ru(acac)
3
] (acac = acetylacetonato, denoted as Ru(
iii
)). The Stern-Volmer constant (
K
SV
) exhibited remarkable stereoselectivity;
K
SV
= 15 900 ± 900 M
−1
for Δ-Ir(
iii
)/Δ-[Ru(acac)
3
] (or Λ-Ir(I
iii
)/Λ-[Ru(acac)
3
]) and 7000 ± 500 M
−1
for Δ-Ir(
iii
)/Λ-[Ru(acac)
3
] (or Λ-Ir(
iii
)/Δ-[Ru(acac)
3
]). The dependence of the emission lifetime on the concentration of Ru(
iii
) indicated that quenching proceeded dynamically. On the basis of the molecular model, it was postulated that a microscopic pocket surrounded by the bulky ligands at the top of adsorbed Ir(
iii
) acted as a site discriminating the chirality of an approaching molecule.
A microscopic pocket surrounded by bulky ligands in Ir(
iii
) acted as a site discriminating the chirality of an approaching molecule. |
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Bibliography: | adsorbed by SAP; enhancement of the luminescent quantum yield of [Ir(bzq) by clay minerals; quantum yield of Ir adsorbed by SAP; Stern-Volmer plots for the quenching of emission from [Ir(bzq) 10.1039/c7nj04688j iii phen)](ClO on emission from [Ir(bzq) adsorption behaviour of Ir + See DOI by [Ru(acac) in various solvents; emission spectra of Ir 2 3 4 in clay suspensions; stereochemical effects of emission from Ir Electronic supplementary information (ESI) available: CD spectra of the enantiomers of [Ir(bzq) in methanol; stereoselective adsorption of [Ru(acac) and synthetic hectorite; comparison of the stereochemical effects on saturated adsorption between [Ir(bzq) (phen) by an ion-exchange adduct of chiral Ir and [Ru(phen) ] adsorbed by synthetic saponite; quenching effects of [Ru(acac) |
ISSN: | 1144-0546 1369-9261 |
DOI: | 10.1039/c7nj04688j |