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Several γ‐cyclodextrin (CD) derivatives mono‐ or di‐substituted by pyrenes at the primary rim of the CD were demonstrated to aggregate into nano‐strips in aqueous solutions, with the pyrene moieties interpenetrating into γ‐CD cavities. The hydrophobic complexation‐induced aggregation provides a rigid chiral environment for the pyrenes and leads to significant electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) activities, giving unprecedently high gabs and glum values up to 4.3×10−2 and 5.3×10−2, respectively. The aggregates lead to excimer emission with high quantum yields and show BCPL and BiCPL up to 338. 6 M−1 cm−1 and 169.3 M−1 cm−1, respectively. [ABSTRACT FROM AUTHOR]

A supramolecular strategy for detecting the concentration of polyamines has been established through competitive/synergetic complexation among polyamines, CB[7], γ-CD, and pyrene derivatives, which allows for convenient, rapid, and high throughput spectral/visual detection of the concentration of urinary polyamines based on the switching on/off of the pyrene excimer fluorescence. [ABSTRACT FROM AUTHOR]

Reaction of chiral amines with benzaldehydes 3,5-disubstituted by two pyrenes or perylenes afforded corresponding double winged chiral imines, which aggregated to show significantly enhanced circular dichroism spectra at the transition bands of the chromophores in the mixture solutions of DMF and H2O. [ABSTRACT FROM AUTHOR]

N N-PtII-bis(acetylide) complexes [ N N = 4,4′-bis( tert-butyl-2,2′-bipyridine) (dbbpy)] with ethynylpyrene ( Pt-2) or 4-ethynyl-1,8-naphthalimide ligands ( Pt-3) that show long-lived 3IL triplet excited states ( τT = 118.0 μs) were used as new triplet sensitizers for triplet-triplet annihilation (TTA) based upconversion (UC). UC quantum yields of up to 18.1 % were observed. We found that the triplet-triplet energy-transfer (TTET) processes, which are crucial for the TTA UC, were improved by up to 150-fold and 250-fold with Pt-2 (Stern-Volmer quenching constant KSV = 5.70 × 105 M-1) and Pt-3 ( KSV = 9.64 × 105 M-1), respectively, relative to the model complex dbbpy-PtII-bis(phenylacetylide) ( Pt-1) ( KSV = 3.80 × 103 M-1). The efficient upconversion is attributed to the long-lived triplet excited states as well as the high T1-state energy level of the sensitizers Pt-2 and Pt-3. [ABSTRACT FROM AUTHOR]

Pt(ii) Schiff base complexes containing pyrene subunits were prepared using the chemistry-on-complexapproach. This is the first time that supramolecular photochemical approach has been used to tune the photophysical properties of Schiff base Pt(ii) complexes, such as emission wavelength and lifetimes. The complexes show intense absorption in the visible region (= 13100 M−1cm−1at 534 nm) and red phosphorescence at room temperature. Notably, much longer triplet excited state lifetimes (τ= 21.0 μs) were observed, compared to the model complexes (τ= 4.4 μs). The extension of triplet excited state lifetimes is attributed to the establishment of equilibrium between the metal-to-ligand charge-transfer (3MLCT) state (coordination centre localized) and the intraligand (3IL) state (pyrene localized), or population of the long-lived 3IL triplet excited state. These assignments were fully rationalized by nanosecond time-resolved difference absorption spectra, 77 K emission spectra and density functional theory calculations. The complexes were used as triplet sensitizers for triplet–triplet-energy-tranfer (TTET) processes, i.e.luminescent O2sensing and triplet–triplet annihilation (TTA) based upconversion. The O2sensitivity (Stern–Volmer quenching constant) of the complexes was quantitatively evaluated in polymer films. The results show that the O2sensing sensitivity of the pyrene containing complex (KSV= 0.04623 Torr−1) is 15-fold of the model complex (KSV= 0.00313 Torr−1). Furthermore, significant TTA upconversion (upconversion quantum yield ΦUC= 17.7% and the anti-Stokes shift is 0.77 eV) was observed with pyrene containing complexes being used as triplet sensitizers. Our approach to tune the triplet excited states of Pt(ii) Schiff base complexes will be useful for the design of phosphorescent transition metal complexes and their applications in light-harvesting, photovoltaics, luminescent O2sensing and upconversion, etc. [ABSTRACT FROM AUTHOR]