Anthracene-based fluorescent sensors

An anthracene-based fluorescent sensor for transition metal ions (Figure 93) has been developed by Fabbrizzi et al. [120]. They have shown that at an appropriate pH (6-8), the addition of Mn " ", Co or Zn2+ does not affect the fluorescence. However, the addition of Cu or Ni ions results in a sharp... 

Several anthracene-based fluorescent sensors (compound 5 in Figiue 2 is one example) that present different fluorescence responses to Cd " and Zn " in aqueous solutions have been synthesized [45 8]. In these molecules, the PET-quenched fluorescence is restored to the original anthracenic fluorescence in the presence of Zn " whereas addition of Cd " generates an anthracene-Cd " 7i-complex, and the resulting spectrum is red-shifted and broadened [47]. However, anthracene-based sensors for Cd " have not been utilized in cell imaging, possibly because of the instability of the d-7i complex of Cd " in biological conditions. 

A related anthracene-based ditopic sensor (11.28) has been constructed, which can recognise diammonium cations along the same lines as 3.103 (Section 3.12.3). Use of the anthracene-derived group as a spacer as in 11.27 gives fluorescent recognition of 11 N1 (Cl I NI I3+ guests as a function of spacer length.20... 

Qing G, He Y, Chen Z et al (2006) Sensitive fluorescent sensors for malate based on calix[4] arene bearing anthracene. Tetrahedron Asymmetry 17 3144—3151... 

A further step in the development of fluorescent sensors based on [Zn (tren)] + and anthracene fragments is the construction of a cage-shaped host. For example, 44 can be obtained by reacting the ligand 43 with two equivalents of terephtalal-dehyde and subsequent reduction of the four imine bonds of the Schiff base. 

Yoon, Kim and co-workers have reported a highly effective fluorescent sensor for dUiydrogen phosphate based on a 1,8-disubstituted-anthracene-dimer macrocycle bridged by two imidazolium subimits (68) [81]. 

Fabbrizzi, L. Licchelli, M. Pallavicini, P. Perotti, A. Sacchi, D. A fluorescence sensor for transition metal ions based on anthracene. Angew. Chem.,Int. Ed. Engl. 1994, 33 (19). 1975-1977. 

Crown ethers can also be used to develop fluorescent sensors. The De Silva group was the first to use crown-ether-based ionophores and developed the photoinduced electron transfer (PET) sensor. In their system (Figme 3b), a methylene spacer connected an anthracene fiuorophore and an aza-18-crown-6 receptor. The lone pair of the nitrogen atom on the receptor quenches the fluorescence owing to PET. Once potassium ion binds to the aza-18-crown-6, the PET process is turned off and fluorescence is turned on. Electrochemical sensors are also available, where the ion-selective electrode (ISE) made by a modified crown ether is popular (Figure 3c). ... 

In 2004, Zhao and James et developed the anthracene-based chiral boronic acid fluorescent sensors 5 and 6, with the a-methylbenzylamine as the chirogenic centre (Eigure 6.6). It is supposed that a cyclic adduct can be formed between the bis-boronic acid sensor and tartaric acids. Based on the fluorescence response of the bis-boronic acid sensor, drastically different fluorescence responses toward the two enantiomers were observed in the acid/ neutral pH range (Figure 6.7). For example, the (i )-sensor shows substantially increased fluorescence in the presence of o-tartaric acid at pH 8.3. In the presence of L-tartaric acid, however, there was no fluorescence enhancement (Figure 6.8a). 

One of the first alkali metal cation chemosensors was based on the molecular architecture of the anthracene derivative (Figure 16.2c) [9]. Substitution of the simple tertiary amino group with an azacrown macrocycle resulted in fluorescence of the chemosensor responding to protons and potassium cations (Figure 16.5a). Further increase in selectivity of the sensor can be achieved via reduction of Brpnsted s basicity of the macrocycle. On the other hand, this modification must retain the electron donor character of the receptor in order to preserve the PET mode of... 

Duprey, J.-L. H. A. Bassani, D. M. Hyde, E. L Ludwig, C. Rodger, A. Vyle, J. S. Wilkie, J. Zhao, Z.-Y Tucker, J. H. R. Anthracene-modified ohgonncleotides as fluorescent DNA mismatch sensors discrimination between varions base-pair mismatches. Supramol. Chem. 2011, 23, 273-277. 

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