Emissive Features of Perylene Diimide Derivative with β-Cyclodextrin: Probing the role of inter and intramolecular interactions.

Perylene diimide (PDI) derivatives have been extensively explored as chromophoric dyes for functional organic materials. Here, the custom synthesized tyrosine appended perylene diimide (PDI-Tyr) derivative has shown strong aggregation in aqueous medium diminishing its emissive features, which was surpassed by the supramolecular interaction with β-cyclodextrin (β-CD). Complex formation between PDI-Tyr and β-CD, proposed from the absorption and emission studies, have been substantiated by the H-NMR, ITC and geometry optimization data.

-Sulfonatocalix[6]arene-Functionalized Gold Nanoparticles: Applications in Drug Delivery and Bioimaging.

Surface-functionalized noble metal nanoparticles with macrocyclic hosts have attracted enormous research interest owing to their applications in drug delivery, catalysis, bioimaging, etc. Stable -sulfonatocalix[6]arene-functionalized gold nanoparticles (SCx6AuNPs) of the sizes ∼7.5 nm have been synthesized and characterized by using UV-vis absorption, transmission electron microscopy, and surface-enhanced Raman spectroscopy measurements.

Enhanced Antibacterial Activity of Levofloxacin with Cucurbit[7]uril-Functionalized Gold Nanoparticles.

Bacterial infection is one of the major concerns of the growing society, and over the years, different permutations and combinations of various drugs and adjuvants have been attempted, which led to considerable improvements in the efficacy of the antibacterial drugs. In this regard, macrocyclic receptors such as cyclodextrin, cucurbiturils, calixarene, etc., have played a major role by modulating the drug properties that supplement the antibacterial efficacy.

Dual catalytic activity of a cucurbit[7]uril-functionalized metal alloy nanocomposite for sustained hydrogen generation: hydrolysis of ammonia borane and electrocatalysts for the hydrogen evolution reaction.

H is one of the most attractive fuel alternatives to the existing fossil fuels that cause detrimental environmental issues. Thus, there has been an upsurge in the research on the production of green hydrogen. In this view, cucurbit[7]uril (CB7)-functionalized Co:Ni alloy nanocomposites with different compositions, reported here for the first time, were synthesized to synergise the catalytic activities of a nanoalloy and CB7 and screened for hydrogen generation hydrolysis of ammonia borane (AB).

Spectroscopic features of a perylenediimide probe for sensing amyloid fibrils: imaging of Aβ-aggregates in a model organism.

Customised perylenediimide (PDI) chromophores find diverse applications not only as chemosensors, inorganic-organic semiconductors, photovoltaics, photocatalysts, , but also in protein surface engineering, bio-sensors and drug delivery systems. This study focuses on the interaction of a custom synthesized phenylalanine derivatized perylenediimide (L-Phe-PDI) dye with a model protein, insulin, and its structurally distinct fibrils to develop fluorescence sensors for fibrillar aggregates and imaging applications. Detailed photophysical studies revealed that L-Phe-PDI gets aggregated in the presence of insulin and causes emission quenching at pH 7.

Supramolecular assembly of coumarin 7 with sulfobutylether-β-cyclodextrin for biomolecular applications.

Coumarins, in general, exhibit a wide range of photophysical characteristics and are highly sensitive to their microenvironment, and, therefore, their fluorescence characteristics have attracted immense attention as sensors in chemical and biological systems. In the present study, the supramolecular interaction of a bichromophoric coumarin dye, namely, Coumarin 7 (C7) with sulfobutylether-β-cyclodextrin (SBEβCD) macrocyclic host at different pH conditions has been investigated by using optical spectroscopic techniques such as absorption, steady-state and time-resolved emissions, and circular dichroism measurements and compared with that of βCD. Considerable enhancement in the fluorescence intensity and lifetime of C7 on complexation with SBEβCD proposes that non-radiative processes like TICT behavior are strictly hindered due to the confinement in the host cavity experienced by the C7 dye.

A combination of a graphene quantum dots-cationic red dye donor-acceptor pair and cucurbit[7]uril as a supramolecular sensor for ultrasensitive detection of cancer biomarkers spermine and spermidine.

In a unique approach, the combination of a donor-acceptor pair of hydroxy graphene quantum dots (GQDs-OH) and a red-emissive donor-two-acceptor (D-2-A) type dye with pyridinium units (BPBP) and the well-known host cucurbit[7]uril (CB[7]) has been exploited as a supramolecular sensing assembly for the detection of cancer biomarkers spermine and spermidine in aqueous media at the sub-ppb level based on the affinity-driven exchange of guests from the CB[7] portal. In the binary conjugate, green fluorescent GQDs-OH transfers energy to trigger the emission of the dye BPBP and itself remains in the turn-off state. CB[7] withdraws the dye from the surface of GQDs-OH by strong host-guest interactions with its portal, making GQDs-OH fluoresce again to produce a ratiometric response.

Cucurbituril-Based Supramolecular Assemblies: Prospective on Drug Delivery, Sensing, Separation, and Catalytic Applications.

Precise control over the stimuli-responsive noncovalent interactions operative in a complex molecular system has emerged as a convenient way to realize applications in the detection and sensing of trace analytes, metal ion separation, uptake-release, nanoparticle synthesis, and catalytic activity. This feature article focuses on the attributes and advantages of noncovalent host-guest interactions involving cucurbituril homologues (CBs) with a wide range of organic and inorganic guests, starting from organic dyes to drugs, proteins, surfactants, metal ions, and polyoxometalates. The unique structural features of CBs provide interaction sites for cations at the portals, polyanions at the periphery, and hydrophobic groups in its cavity.

Fibril-induced neurodegenerative disorders in an Aβ-mutant Drosophila model: therapeutic targeting using ammonium molybdate.

The ability of polyanionic molybdate to inhibit and degrade protein fibrils both in vitro (insulin protein) and in vivo (Drosophila fly model) has been demonstrated. We establish the disappearance of fibrillar structures and recovery from neurodegenerative disorders in molybdate-treated Aβ42-mutant Drosophila flies as compared to the untreated ones, corroborating the therapeutic ability of ammonium molybdate towards the treatment of Alzheimer's disease.

Metal-Free Supramolecular Catalytic Hydrolysis of Ammonia Borane through Cucurbituril Nanocavitands.

Ammonia 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.

Interaction of esculetin with aluminium ion by spectroscopic studies and isothermal titration calorimetry: a probable molecule for chelation therapy.

The use of aluminium has made significant impact in our life by virtue of its attractive properties. The lack of essentiality of aluminium in biosphere indicated that its accumulation above certain level is undesirous. Esculetin (6,7-dihydroxy coumarin) is an excellent aluminium ion chelator and the chelation interaction was studied by exploiting the absorption and fluorescence behavior of esculetin.

Supramolecular interaction of sanguinarine dye with sulfobutylether-β-cyclodextrin: modulation of the photophysical properties and antibacterial activity.

The noncovalent host-guest interaction of sanguinarine (SGR), a benzophenanthridine alkaloid, with a nontoxic, water soluble sulfobutylether-β-cyclodextrin (SBEβCD, commercially available as Captisol) macrocyclic host has been investigated using ground-state optical absorption, and steady-state and time-resolved fluorescence measurements. The pH-dependent changes in the absorbance of the dye at 327 nm showed a p value of 7.5, which has been shifted to 8.

Cooperative enhancement of antibacterial activity of sanguinarine drug through p-sulfonatocalix[6]arene functionalized silver nanoparticles.

The 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.

Supramolecular Assembly Induced Emission of Thiazole Orange with Sulfobutylether β-cyclodextrin: A Stimuli-Responsive Fluorescence Sensor for Tyramine.

Modulation 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.

Redox-mediated Negative Differential Resistance (NDR) Behavior in Perylenediimide Derivative: A Supramolecular Approach.

Deaggregated 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.

Supramolecular Nanorods of (N-Methylpyridyl) Porphyrin With Captisol: Effective Photosensitizer for Anti-bacterial and Anti-tumor Activities.

Porphyrins, 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.

Ultra-Bright Rhodamines with Sulfobutylether-β-Cyclodextrin: A Viable Supramolecular Dye Laser in Aqueous Medium.

Although 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 ).

Stimuli-Responsive Cucurbit[7]uril-Mediated BSA Nanoassembly for Uptake and Release of Doxorubicin.

We 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.

Reversible Insulin Hexamer Assembly Promoted by Ethyl Violet: pH-Controlled Uptake and Release.

Therapeutically improved long-acting insulin preparations require in-depth understanding of the hexamer assembly, structural selectivity, and its stability in solution. This Letter demonstrates, for the first time, an efficient method for the hexamerization of human insulin by a structure-specific triphenylmethane (TPM) dye, Ethyl Violet (EV), particularly, in the absence of Zn. Upon detailed spectroscopic evaluation and comparison with other TPM homologues, we establish that the diethylamino phenyl arms of EV are specific and effective in clipping the three dimer helices in a hexameric assembly.

Recognition-mediated cucurbit[7]uril-heptamolybdate hybrid material: a facile supramolecular strategy for (99m)Tc separation.

We report the construction of a novel non-covalently held cucurbit[7]uril-heptamolybdate hybrid material for the first time, and demonstrate its application as a generator bed for the facile and efficient separation of the (99m)Tc radiotracer, which is in demand for several theranostic applications.

Inhibition and disintegration of insulin amyloid fibrils: a facile supramolecular strategy with p-sulfonatocalixarenes.

We reveal the ability of p-sulfonatocalix[4/6]arene to effectively inhibit the fibril formation in human insulin and demonstrate its potential to disintegrate the mature fibrils, a promising supramolecular strategy to combat amyloidosis.

Cucurbit[8]uril-templated H and J dimers of bichromophoric coumarin dyes: origin of contrasting emission.

We report the supramolecular control and mechanism for the contrasting dimer emission from selected bichromophoric coumarin dyes caught in the cucurbit[8]uril cavity-a facile approach to developing photo-responsive molecular assemblies through structural tuning.

Metal-ion-mediated assemblies of thiazole orange with cucurbit[7]uril: a photophysical study.

The formation of molecular superstructures by metal-ion-mediated noncovalent self-assembly has been demonstrated using the macrocycle, cucurbit[7]uril (CB7), and the dye, thiazole orange (TO), as building blocks. Interestingly, the association of these molecular building blocks can be tuned by the chemical environment, leading to self-assembled structures of different stoichiometries, which is supported by absorption, fluorescence, (1)H NMR, and AFM measurements. Most importantly, the self-assembly process of the CB7/TO/metal ion system is observed to be remarkably different for alkali (Na(+)) and alkaline earth (Ca(2+)) metal ions.

Molecular-recognition-assisted pKa shifts and metal-ion-induced fluorescence regeneration in p-sulfonatocalix[6]arene-encapsulated acridine.

The host-guest interactions of cationic (AcH(+) ) and neutral (Ac) forms of the dye acridine with the macrocyclic host p-sulfonatocalix[6]arene (SCX6) were investigated by using ground-state absorption, steady-state and time-resolved fluorescence, and NMR measurements. The cationic form undergoes significant complexation with SCX6 (Keq =2.5×10(4)  M(-1) ), causing a sharp decrease in the fluorescence intensity and severe quenching in the excited-state lifetime of the dye.

Synergistic effect of intramolecular charge transfer toward supramolecular pKa shift in cucurbit[7]uril encapsulated coumarin dyes.

This article presents the process and mechanism of supramolecular pKa shift in two bichromophoric coumarin laser dyes, namely, coumarin 7 (C7), (ΔpK(a) = 4.6) and coumarin 30 (C30), (ΔpK(a) = 3.0), achieved by introducing a synthetic macrocyclic receptor, cucurbit[7]uril (CB7), in aqueous media.