Design of anion-selective PET probes based on azacryptands: the effect of pH on binding and fluorescence properties

Abstract

Design of PET probes for anions working in an aqueous buffered solution is described. The design has been used to develop selective fluorescent probes for sulfate and pyrophosphate. The relationship between the selectivity of receptors towards anions, their conformation, fluorescence response and the pH of the solution has been studied in detail.

FeIII–Salen‐Based Probes for the Selective and Sensitive Detection of E450 in Foodstuff

“…In 1994, Czarnik and Vance reported on the fluorometric detection of PPi with a polyamine‐modified anthracene derivative in H 2 O . The Kataev group described the encapsulation and detection of PPi with an azacryptand‐based receptor (Figure , right) . Probably the first example of discrimination of PPi over ATP was reported in 2004 by Hong and co‐workers using a binuclear Zn II ‐bis(2‐pyridylmethyl)amine complex.…”

Acid‐Regulated Switching of Metal Cation and Anion Guest Binding in Halogen‐Bonding Rotaxanes

“…With rotaxane 2 , the binding of different transition metal cations, added as their perchlorate salts, in acetonitrile elicited contrasting fluorescence responses. The binding of closed‐shell Zn 2+ resulted in a dramatic increase in the rotaxane's fluorescence intensity (Figure B), which was likely primarily due to metal coordination of the Lewis basic lone pair on the macrocycle component's tertiary amine functionality responsible for photoinduced electron transfer (PET) quenching of the anthracene's fluorescence . In stark contrast, the binding of redox‐active Cu 2+ and Ni 2+ to rotaxane 2 elicited significant fluorescence quenching (Figure C and Figures S4–3, respectively) which probably results from an electron transfer quenching mechanism from the photoexcited anthracene moiety to the respective transition metal centre …”

“…This clearly indicates that despite the presence of Lewis basic nitrogen atoms on the iodotriazoles, the amine unit is preferentially protonated. In further support, HBF 4 addition to rotaxane 2 led to a large turn ‐ on fluorescence response from the anthracene fluorophore (Figure S4‐4), which results from the loss of PET fluorescence quenching pathways upon amine protonation …”

“…In further support, HBF 4 addition to rotaxane 2 led to al arge turn-on fluorescencer esponse from the anthracene fluorophore (Figure S4-4), which results from the loss of PET fluorescence quenching pathways upon amine protonation. [32,37,40,41] The cationic binding cavities of rotaxanes [1·2 H + ](BF 4 À ) 2 and [2·H + ]BF 4 À were now expected to bind anions strongly in competitives olventm edia. Indeed, in the organic-aqueous solvent mixture CDCl 3 /CD 3 OD/D 2 O( 45:45:10 v/v/v), Cl À addition to rotaxane [1·2 H + ](BF 4 À ) 2 once again elicited numerouschanges to its 1 HNMR spectrum( Figure 5A), the most noteworthy of which are the downfield shifts of H d andH 4 ,w hich likely arise from anion binding in close proximity to the interlocked cavity which results in furthers tructural changes to the rotaxane.…”

Synthesis and applications of fluorescent-tagged scale inhibitors in water treatment. A review

“…A significant number of papers are devoted to the usage of naphthalic acid imide derivatives as fluorescent markers [59][60][61][62][63]. This class of compounds has already found a wide range of practical applications as fluorescent markers in biochemical analysis or sensors [59,60].…”