Sulfated β‐Cyclodextrin Templated Assembly and Disassembly of Acridine Orange: Unraveling Contrasting Binding Mechanisms and Light Off/On Switching

Abstract

Present article reports the intriguing aggregation‐deaggregation behavior of acridine orange (AOH+), as induced by the water soluble macrocyclic host, sulfated β‐cyclodextrin (SCD), and the results are compared with those obtained earlier in the presence of sulfobutylether‐β‐cyclodextrin (SBEβCD) host. While monomeric form of AOH+ is widely investigated, the aggregation behavior of AOH+ still remains to be quite less explored, though dye aggregation has a great consequence for its uses as a fluorescence probe for various biological and other microheterogeneous systems. It is observed that aggregation/dimerization of AOH+ is highly assisted by SCD at lower host concentration, resulting a drastic fluorescence quenching for AOH+. In contrast, at higher SCD concentrations the host drives the initially formed AOH+ aggregates/dimers to convert into the monomeric AOH+‐SCD exo and inclusion complexes, ensuing a huge enhancement for AOH+ fluorescence. Though similar host assisted sequential fluorescence turn‐off and turn‐on for AOH+ was also observed earlier on using SBEβCD host (Phys. Chem. Chem. Phys. 2017, 19, 24166), in the present case the effect is exceptionally very large, suggesting the SCD to be a very efficient host to induce such a fluorescence Off‐On switching for the cationic dye AOH+, as explored elaborately in the present study following various photochemical and other complementary measurements.

Stimulus-Responsive Supramolecular Host–Guest Assembly of a Cationic Pyrene Derivative with Sulfated β-Cyclodextrin

“…In this regard, the sulfated derivative of β-cyclodextrin (SCD), where the hydroxyl group of both the upper and lower rims of β-cyclodextrin is substituted with sulfate groups, is expected to induce more efficient aggregation, for cationic guest molecules, as compared to p -sulfonatocalixarene because SCD carries a relatively much higher negative charge density. In spite of having these technical and logistic advantages associated with sulfated β-cyclodextrin over p -sulfonatocalixarene, there are limited reports of interaction of organic guest molecules with this important polyanionic macrocyclic host molecule, that is, SCD, , as compared to a large volume of work performed with p -sulfonatocalixarene and reviewed in literature . Thus, many opportunities still remained to be explored for this polyanionic host in the field of supramolecular host–guest aggregation and its potential uses in different areas.…”

Nanomaterials with Supramolecular Assembly Based on AIE Luminogens for Theranostic Applications

“…[ 93 ] Moreover, Sayed and co‐workers reported off/on switching of acridine orange mediated by fluorescence light induced by their assembly and disassembly templated by sulfated β‐CD. [ 94 ] Recently, Zhu and co‐workers also constructed crystalline materials based on γ‐CD‐MOF with circularly polarized luminescence (CPL). [ 95 ] Intriguingly, different CPL effects were observed when different guest luminophores were added as the γ‐CD‐MOF is capable of selectively encapsulating guest molecules owing to the size‐dependent host–guest property.…”