Room temperature phosphorescence from a guest molecule confined in the restrictive space of an organic-inorganic supramolecular assembly

Stable room-temperature phosphorescence of guest aromatic molecules was achieved by the effective suppression of oxygen quenching. The organic capsule (first wall) suppressed static oxygen quenching by enclosing a guest molecule, and dynamic quenching via the capsule opening-closing process was well suppressed and manipulated by the intercalation of this capsule into the restrictive space between clay nanosheets (second wall)

Supramolecular-Surface Photochemistry: Assembly and Photochemistry of Host–Guest Capsules on Silica Surface

Host cavitands and organic guest molecules independently adsorbed on silica particles when mixed and shaken in the presence of a few drops of water underwent intra- and interparticle migration to form capsular complexes that were not formed either in water or organic solvents. Importance of cavitand migration and tumbling on silica surface was established by demonstrating that covalently linked cavitands do not form capsular complexes. The encapsulated guests exhibited selective photochemistry as they do within an organic capsule in solution

Photoinduced electron transfer across an organic molecular wall: octa acid encapsulated ESIPT dyes as electron donors

Efficient photoinduced electron transfer from proton transfer dyes encapsulated within water soluble supramolecular host octa acid to electron acceptors present outside the capsule was observed in aqueous solution. N-Methylpyridinium iodide was found to be the best acceptor compared to 4,4′-dimethylviologen dichloride, most likely due to its better binding with the exterior of the host octa acid walls

Correction: Photoinduced electron transfer across an organic molecular wall: octa acid encapsulated ESIPT dyes as electron donors

Correction for ‘Photoinduced electron transfer across an organic molecular wall: octa acid encapsulated ESIPT dyes as electron donors’ by Fabiano S. Santos et al., Photochem. Photobiol. Sci., 2017, 16, 840–844

Excited state chemistry of flavone derivatives in a confined medium: ESIPT emission in aqueous media

The excited state behavior of two flavone derivatives 3-hydroxyflavone and 4′-N,N-diethylaminoflavonol in a confined medium indicates that supramolecular effects could alter the nature of the fluorescence emission. Within the octa acid host the neutral unionized species of these two dyes are present showing large Stokes shifted emission due to intramolecular proton transfer, a pattern different from that in aqueous medium

Excited state behavior of benzoxazole derivatives in a confined environment afforded by a water soluble octaacid capsule

[Display omitted] •Dual fluorescence emission free in solution.•Fluorescence emission within host OA similar to organic solvents.•Large Stokes’ shift due to ESIPT unlike that in aqueous medium.•Fluorescence emission tailored by the confinement in octaacid.•Within the host OA the ESIPT dyes are shielded from the bulk water. This feature article presents a brief description of the excited state intramolecular proton transfer mechanism (ESIPT), describes the solvent dependence of the ESIPT phenomenon and present the potential applications that can be envisaged for these fluorophores. Photophysics of three dye molecules exhibiting ESIPT were examined free in solution and within a water soluble supramolecular host, octaacid (OA) by steady-state and time resolved fluorescence emission techniques. Inclusion of the above dyes within OA was confirmed by 1H NMR spectra. The free and octaacid complexed dyes had electronic absorption in the UV region. Within the OA container the fluorophores showed fluorescence emission similar to that in benzene, dichloromethane and acetonitrile. Moreover, the observed large Stokes’ shift in the emission of the dyes when confined within OA capsule was unlike that in aqueous medium. The results suggest that a confined medium is a powerful tool to tailor the fluorescence emission of ESIPT compounds in aqueous media

Confinement effect on the photophysics of ESIPT fluorophores

The photophysics of three benzothiazole derivatives that exhibit excited state intramolecular proton transfer (ESIPT) were investigated in a confined medium afforded by the water soluble supramolecular host octaacid (OA). The dye@(OA)2 inclusion complexes were probed by UV-Vis absorption, steady-state and time resolved fluorescence emission techniques. Comparison studies of the free dyes in solution were also conducted. All three benzothiazole derivatives free in solution and as OA complexes in water absorb in the UV region. The fluorescence maxima of the OA complexes in water are similar to those in an apolar environment. This is different from the emission behavior of the dyes dissolved alone in water. The observed Stokes shift when confined within OA is related to the intramolecular proton transfer mechanism. Within OA only neutral species are present, indicating that these compounds are shielded from the bulk water. The excited state behavior of the benzothiazole derivatives in a confined medium indicates that supramolecular effects significantly alter the nature of the fluorescence emission

RhythmEdge: Enabling contactless heart rate estimation on the edge

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