Study of cavity size and nature of bridging units on recognition of nucleotides by cyclophanes

Abstract

We synthesized a few novel cyclophanes CP-1 to CP-4 containing anthracene units linked together through different bridging and spacer groups and have investigated their interactions with various nucleosides and nucleotides. Of these systems, CP-1 and CP-3 showed selectivity for 5'-GTP and 5'-ATP as compared to other nucleotides and nucleosides, whereas negligible selectivity was observed with CP-2 and CP-4. Interestingly, CP-1, CP-2 and CP-3 exhibited significant binding interactions with the fluorescent indicator, 8-hydroxy-1,3,6-pyrene trisulfonate (HPTS), resulting in the formation of non-fluorescent complexes. Titration of these complexes with nucleosides and nucleotides resulted in the displacement of HPTS, leading to the revival of its fluorescence intensity. It was observed that 5'-GTP induced the maximum displacement of HPTS from the complex [CP-1·HPTS] with an overall fluorescence enhancement of ca. 150-fold, while 5'-ATP induced ca. 45-fold. Although the displacement of HPTS from the complexes [CP-2·HPTS] and [CP-3·HPTS] was found to be similar to that of [CP-1·HPTS], these complexes showed lesser selectivity and sensitivity. In contrast, negligible displacement of HPTS was observed from the complex [CP-4·HPTS] under similar conditions. These results indicate that CP-1, having a well-defined cavity and good electron acceptor (viologen), is capable of forming selective and stable complexes. Though CP-2 and CP-3 retain the good electron acceptor (viologen), their reduced aromatic surface and larger cavity, respectively, resulted in lesser sensitivity. In contrast, CP-4 having a large cavity and a poor acceptor (1,2-bis(pyridin-4-yl)ethene) showed negligible selectivity, thereby indicating the importance of cavity size, bridging unit and aromatic surface on biomolecular recognition properties of cyclophanes.

Smartphone-based fluorescence detection of bisphenol A from water samples

“…Previous research has demonstrated HPTS quenching by electron transfer with viologen moieties and in p-bond interactions with other aromatic compounds, including caffeine, theobromine, and theophylline. [25][26][27][28] Based on these electrontransfer binding interactions conrmed previously through uorescence and NMR titration and corroborated with cyclic voltammetry or mathematical modelling, we hypothesized that HPTS uorescence may be quenched through a similar binding complex with BPA, and that this may be distinguishable from quenching by similarly structured EDC and hormone comparators. To answer this, we investigated the BPA-HPTS binding interaction in contrast with the binding interactions of 17b-estradiol (E2), a natural estrogen, nonylphenol (NP), a structurally similar suspected endocrine disruptor, and nonspecic compounds in wastewater effluent (Fig.…”

Molecular Receptors for Recognition and Sensing of Nucleotides

“…The combination of a water‐soluble ammonium‐pillar[6]arene with dapoxyl sodium sulfonate, as well as Zn II complexes with fluorescein, can selectively detect ATP in buffered solutions. In contrast, GTP prefers to displace HPTS (8‐hydroxypyrene‐1,3,6‐trisulfonic acid) from the positively charged cyclophanes and a porphyrin–pyridinium conjugate . A similar strategy was used by Schäferling and co‐workers, who used HPTS together with bipyridinium salt modified with triethylamine subunits .…”

Anthracene‐Based Cyclophanes with Selective Fluorescent Responses for TTP and GTP: Insights into Recognition and Sensing Mechanisms

“…[20][21][22] This work hasi nspired other groups to evaluate interactions between cyclophanes andn ucleotides in aqueous solution. [23][24][25][26][27][28][29] These macrocycles have also been found to interact with G-quadruplex [30] and showa ntiproliferativea ctivity. [31] Interestingly,b is-naphthaline-derived macrocycles and bis-anthracene receptor 2 containing 2,2'-oxybis(ethylamine) as linker can recognize thymine-thymine mismatches in DNA ( Figure 1).…”

“…In the 1990s, Lehn proposed the use of cyclophanes as artificial receptors for nucleosides and nucleotides . This work has inspired other groups to evaluate interactions between cyclophanes and nucleotides in aqueous solution . These macrocycles have also been found to interact with G‐quadruplex and show antiproliferative activity .…”