Photomodulation of ultrastable host–guest complexes in water and their application in light-controlled steroid release

Máximo, Patrícia; Colaço, Miriam; Pauleta, Sofia R.; Costa, Paulo J.; Pischel, Uwe; Parola, A. Jorge; Basílio, Nuno

doi:10.1039/d2qo00423b

Cited by 11 publications

(11 citation statements)

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“…Nonetheless, the resulting CB–guest complexes possess larger stability constants, which can even be several orders of magnitude higher for guests bearing a positive charge [ 15 , 16 , 17 , 18 ]. All these factors provide a solid premise for their implementation as on–off switches [ 19 , 20 ] in targeted drug delivery [ 21 , 22 , 23 , 24 , 25 ], enzymatic assays [ 26 ], and as supramolecular architectures–bracelets and necklaces [ 27 , 28 , 29 ]. Due to their low toxicity and high biocompatibility, CBs and their resulting complexes are utilized in various branches of pharmacy and medicine [ 30 , 31 , 32 ].…”

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confidence: 99%

Metal-Assisted Complexation of Fluorogenic Dyes by Cucurbit[7]uril and Cucurbit[8]uril: A DFT Evaluation of the Key Factors Governing the Host–Guest Recognition

et al. 2023

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With the emergence of host-guest systems, a novel branch of complexation chemistry has found wide application in industries such as food, pharmacy, medicine, environmental protection and cosmetics. Along with the extensively studied cyclodextrins and calixarenes, the innovative cucurbiturils (CB) have enjoyed increased popularity among the scientific community as they possess even better qualities as cavitands as compared to the former molecules. Moreover, their complexation abilities could further be enhanced with the assistance of metal cations, which can interestingly exert a dual effect on the complexation process: either by competitively binding to the host entity or cooperatively associating with the CB@guest structures. In our previous work, two metal species (Mg2+ and Ga3+) have been found to bind to CB molecules in the strongest fashion upon the formation of host–guest complexes. The current study focuses on their role in the complex formation with three dye molecules: thiazole orange, neutral red, and thioflavin T. Various key factors influencing the process have been recognized, such as pH and the dielectric constant of the medium, the cavity size of the host, Mn+ charge, and the presence/absence of hydration shell around the metal cation. A well-calibrated DFT methodology, solidly based and validated and presented in the literature experimental data, is applied. The obtained results shed new light on several aspects of the cucurbituril complexation chemistry.

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Section: Introductionmentioning

confidence: 99%

Metal-Assisted Complexation of Fluorogenic Dyes by Cucurbit[7]uril and Cucurbit[8]uril: A DFT Evaluation of the Key Factors Governing the Host–Guest Recognition

et al. 2023

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“…50% of DA is released in the light-induced cascade. 53 On shining visible light (>550 nm) on the 1c form, 1o is formed back quantitatively ( Φ 1c → 1o = 0.001) 51 and consequently the initial situation is restored (see Fig. 3c).…”

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“…5000); 49,52 see Table 1. The DTE photoswitch should show a large CB8-affinity differentiation for its activated and nonactivated forms, 51 while being a poor binder for CB7 in any of its forms. To our satisfaction, switch 1 in both forms (1o and 1c) shows very low binding (ca.…”

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confidence: 99%

“…[29][30][31][32][33][34][35][36][37][38][39] This has been explored as well in the context of CBn chemistry. [40][41][42][43] Among other photoswitches, dithienylethenes (DTEs) [44][45][46] have been proven very useful [47][48][49][50][51] and will also play a crucial role in the present work. The design approach towards the envisioned light-controlled supramolecular cascade is outlined in Fig.…”

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confidence: 99%

“…29–39 This has been explored as well in the context of CBn chemistry. 40–43 Among other photoswitches, dithienylethenes (DTEs) 44–46 have been proven very useful 47–51 and will also play a crucial role in the present work.…”

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Phototransduction in a supramolecular cascade: a mimic for essential features of the vision process

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Remón

et al. 2023

Chem. Commun.

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Photofunctional Scope of Fluorescent Dithienylethene Conjugates with Aza‐Heteroaromatic Cations

et al. 2023

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A series of dithienylethene (DTE) photoswitches with aza‐heteroaromatic cationic moieties is synthesized. The switches are characterized regarding their photochemical and photophysical properties in acetonitrile and in water. The efficiency of the switching and the photostationary state composition depend on the degree of π‐conjugation of the heteroaromatic systems. Thus, DTEs with acridinium‐derived moieties have very low quantum yields for the ring‐closing process, which is in contrast to switches with pyridinium and quinolinium moieties. All switches emit fluorescence in their open forms. The involved electronic transitions are traced back to an integrative picture including the DTE core and the cationic arms. The emission can be fine‐tuned by the π‐conjugation of the heteroaromatic cations, reaching the red spectral region for DTEs with acridinium moieties. On ring‐closing of the DTEs the fluorescence is not observable anymore. Theoretical calculations point to rather low‐lying energy levels of the highly conjugated ring‐closed DTEs, which would originate near‐infrared emission (> 1200 nm). The latter is predicted to be very weak due to the concurrent non‐radiative deactivation, according to the energy‐gap law. In essence, an ON–OFF fluorescence switching as the result of the electrocyclic ring‐closing reaction is observed.

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Photomodulation of ultrastable host–guest complexes in water and their application in light-controlled steroid release

Abstract: Host–guest complexation of dithienylethene photoswitches with cucurbit[8]uril leads to photoresponsive binding pairs with picomolar affinity in water.

Cited by 11 publications

References 84 publications

Metal-Assisted Complexation of Fluorogenic Dyes by Cucurbit[7]uril and Cucurbit[8]uril: A DFT Evaluation of the Key Factors Governing the Host–Guest Recognition

Metal-Assisted Complexation of Fluorogenic Dyes by Cucurbit[7]uril and Cucurbit[8]uril: A DFT Evaluation of the Key Factors Governing the Host–Guest Recognition

Phototransduction in a supramolecular cascade: a mimic for essential features of the vision process

Photofunctional Scope of Fluorescent Dithienylethene Conjugates with Aza‐Heteroaromatic Cations

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