Angew Chem Int Ed Engl
September 2024
Pores containing molecular adapters provide internal selective binding sites, thereby allowing the stochastic sensing of analytes. Herein, we demonstrate that semiaza-bambusuril (BU) acts as a non-covalent molecular adapter when lodged within the lumen of the wild-type α-hemolysin (WT-αHL) protein pore. Because the bambusurils are recognized as anion receptors, the anion binding site within the adapter-nanopore complex allows the detection of chloride anions, thus converting a non-selective pore into an anion sensor.
View Article and Find Full Text PDFIn the last two decades, perchlorate salts have been identified as environmental pollutants and recognized as potential substances affecting human health. We describe self-assembled monolayers (SAMs) of novel semiaza-bambus[6]urils (semiaza-BUs) equipped with thioethers or disulfide (dithiolane) functionalities as surface-anchoring groups on gold electrodes. Cyclic voltammetry (CV) with Fe(CN) as a redox probe, together with X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and ellipsometry, were employed to characterize the interactions at the interface between the anchoring groups and the metal substrate.
View Article and Find Full Text PDF-Bambus[6]urils efficiently transport anions across lipid membranes. A systematic modification of their lipophilic side chains to include various alkyl groups and thioethers reveals that the most efficient chloride transporters are those that agree with Lipinski's rule-of-lipophilicity, exhibiting clog values close to 5. Furthermore, vesicle anion-transport assays show that the new anion-transporters are independent of the cation identity but exhibit high anion selectivity, NO > Br > Cl > SO, in agreement with the Hofmeister series.
View Article and Find Full Text PDFAmmonia borane (AB) is considered a potential "on-board" hydrogen storage material. However, its implementation as a hydrogen reservoir in fuel cells is lacking due to the extremely slow release of hydrogen at room-temperature hydrolysis. In this study, a metal-free supramolecular strategy is demonstrated at room temperature to increase the hydrolysis rate and yield of hydrogen along with significant reduction in ammonia release by using cucurbit[5/8]uril (CB5/CB8) nanocavitands as catalysts.
View Article and Find Full Text PDFThe amelioration of antibacterial efficacy along with the reduced minimum inhibitory concentration (MIC) of sanguinarine (SGR) drug have been demonstrated through the uptake of SGR by p-sulfonatocalix[6]arene functionalized silver nanoparticles. The large upward pKa shift and enhanced stability of SGR resulting from the favorable supra-nanomolecular strategy are deciphered into an improved antibacterial drug against different pathogenic micro-organisms including multi drug resistant bacteria.
View Article and Find Full Text PDFModulation and control of stimuli responsive features of molecular assemblies in organized assemblies/cavitand macrocycles have received immense attention in many areas. In this study, we have established the formation of a discrete molecular assembly of thiazole orange (TO) dyes at the portals of the sulfobutylether β-cyclodextrin (SBE βCD) macrocycle leading to the evolution of a strong and distinct emission band from aggregated TO. The supramolecular assembly promoted portal aggregation of TO in its 1 : 4 (SBE βCD : TO) composition, characterized by absorption, fluorescence, circular dichroism, ITC and H NMR measurements, was probed to be selectively responsive to tyramine among other biogenic amines/neurotransmitters.
View Article and Find Full Text PDFDeaggregated perylenediimide (PDI) derivatives exhibit exceptionally high quantum yields, photostability and appropriate molecular features for organic electronics. This work demonstrates a metal-dye-metal framework with a large and stable negative differential resistance (NDR) at ambient conditions, built using a supramolecular strategy. The deaggregation achieved through the encapsulation of the bay-substituted phenyl groups of aggregated (l/d)-Phe-PDI dyes by the β-CD macrocyclic host is validated through detailed spectroscopic and imaging techniques.
View Article and Find Full Text PDFPorphyrins, especially the 5,10,15,20-tetrakis(4--methylpyridyl) porphyrin (TMPyP), are well-accepted as photosensitizers due to strong absorption from visible to near-infrared region, good singlet oxygen quantum yields as well as chemical versatility, all of which can be further modulated through planned supramolecular strategies. In this study, we report the construction of supramolecular nanorods of TMPyP dye/drug with captisol [sulfobutylether-β-cyclodextrin (SBEβCD)] macrocycle through host-guest interaction. The availability of four cationic N-methylpyridyl groups favors multiple binding interaction with the captisol host, building an extended supramolecular assembly of captisol and TMPyP.
View Article and Find Full Text PDFAlthough aqueous dye lasers are much sought after, they have been of no practical use, as laser dyes show a strong tendency for aggregation in water, thus diminishing their optical output. Contributing towards this shortcoming, we studied the noncovalent interactions of two prominent laser dyes, namely, rhodamine 6G and rhodamine B, with a water soluble macrocyclic host, sulfobutylether-β-cyclodextrin (SBE βCD). Spectral changes in the absorption and fluorescence behavior of dyes in presence of the SBE βCD host indicated adequate complex formation between dye and host (K∼10 M ).
View Article and Find Full Text PDFThe interaction between red-emitting pyridinium derivative [4-((1,3)-4-(4-(dimethylamino)phenyl)buta-1,3-dien-1-yl)-1-methylpyridin-1-ium] (DABP) and cucurbit[7]uril was investigated using optical absorption, steady-state and time-resolved fluorescence and anisotropy measurements. The changes in the UV/Vis absorption, fluorescence spectral characteristics and lifetime, with a change in pH, reveal efficient binding of CB7 to the dye molecule. The cucurbit[7]uril encapsulated DABP brings ∼1.
View Article and Find Full Text PDFWe report the construction of a non-toxic nanoassembly of bovine serum albumin (BSA) protein and the cucurbit[7]uril macrocycle as well as its stimuli-responsive breakage with adamantylamine or pH, which restores the protein structure and recognition properties. The assembly showed efficient loading and controlled release of a standard drug, doxorubicin (DOX), and the same was validated in live cells. The cell viability studies documented that the DOX-loaded assembly mask the cytotoxicity of DOX and the toxicity can be revived at the target on demand, triggering its therapeutic activation.
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