96107-96-9

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• 96107-95-8 calix[6]arene 

Relevant academic research and scientific papers

P-Sulfocalix[6]arene as Nanocarrier for Controlled Delivery of Doxorubicin

Given the high toxicity of the anthracycline antibiotic doxorubicin (DOX), it is relevant to search for nanocarriers that decrease the side effects of the drug and are able to transport it towards a therapeutic target Here, the encapsulation of DOX by p-sulfocalix[6]arene (calix) has been studied. The interaction of DOX with the macrocycle, as well as with DNA, has been investigated and the equilibrium constant for each binding process estimated. The results showed that the binding constant of DOX to DNA, KDNA, is three orders of magnitude higher than that to calix, Kcalix. The ability of calixarenes to encapsulate DOX molecules, as well as the capability of the DOX molecules included into the inner cavity of the macrocycle to bind with DNA have been examined. Cytotoxicity measurements were done in different cancer and normal cell lines to probe the decrease in the toxicity of the encapsulated DOX. The low toxicity of calixarenes has also been demonstrated for different cell lines.

Molecular Association of Water-Soluble Calixarenes with Several Stilbene Dyes and Its Application to the Facile Determination of Cationic Surfactant Concentrations

The molecular association of water-soluble p-sulfonatocalix[n]arenes (1n; n = 4, 6, and 8) with several stilbene dyes (D) has been studied by spectrophotometric and 1HNMR methods. It was found that 1n reacts in 1: 1 stoichiometry with, D such as 4-[(4-dimethylamino)styryl]-1-methylpyridinium (St-4Me), 2-[(4-dimethylamino)styryl]-1-methylpyridinium (St-2Me) and 2-[(4-dimethylamino)styryl]-1-ethylpyridinium (St-2Et) iodides to form their complexes (1nD). The apparent association constants for 18-complexes are larger by about ten times than those of 14- and 16-complexes. Examinations of the CPK molecular models and the spectrophotometric studies suggested that 14 complexes D mainly with its 1-methyl- or 1-ethylpyridinium group, whereas 16 complexes D either with its pyridinium ring or with its protonated dimethylamino group in a similar probability, and in 18-complexes the molecule is wholly incorporated into the cavity of 18. The absorbance of D, which was decreased by association with 1n, was regenerated by the addition of other colorless cationic surfactants (A) such as cetylethyldimethylammonium ion. Studies on the substitution reaction of 1nD with A indicated that a 1 : 1 complex (1nA) is formed by releasing a free dye molecule (D). This was applied to a convenient determination of the cationic surfactant concentration in water.

Hexasulfonated Calixarene Derivatives: A New Class of Catalysts, Surfactants, and Host Molecules

Water-soluble hexasulfonated calixarenes with various substituens (1-R) have been sythesized for the first time and applied as host molecules in an aqueous system.Dynamic 1H NMR studies established that calixarene-p-hexasulfonate (1-H) adopts a "winged" or "hinged" conformation in D2O-Me2SO-d6 (2:1 v/v) owing to hydrogen bonding among the OH groups, while 5,11,17,23,29,35-hexasulfonato-37,38,39,40,41,42-hexakis(hexyloxy)calixarene (1-C) adopts a similar conformation in D2O owing to hydrophobic bonding among the hexyl groups.The aggregation behavior in water was examined about 1-C6 and 1-C12.Physical (light-scattering, surface tension, and conductance) and spectral (fluorescence and absorption spectroscopies) studies established that 1-C6 has a cmc at ca. 6E-4 M, as does sodium dodecyl sulfate (SDS), while 1-C12 has no detectable cmc and rather acts as a "unimolecular" micelle.In fact, 1-C6 associated with small molecules (pyrene, 2-anilinonaphtalene, and Orange OT) according to the micelle-like biphasic concentration dependence, while 1-C12 formed host-guest-type 1:1 complexes with these molecules.It was found that these calixarene derivatives efficiently accelerate acid-catalysed hydration of 1-benzyl-1,4-dihydronicotinamide and the reaction proceeds according to the Michaelis-Menten kinetics.In particular, the rate constans for 1-H and 1-CH2COOH, which both have acidic protons to catalyze the reaction and anionic sulfonates to stabilize the cationic intermediate at the two edges of the cavity, were greater by 426-1220-fold than those for noncyclic analogues.These findings indicate that hexasulfonated calixarenes serve as a new class of catalysts, surfactants, and host molecules.This is the first example for the host-guest-type behavior of calixarenes observed in an aqueous system.

NEW WATER-SOLUBLE HOST MOLECULES DERIVED FROM CALIXARENE

4-Sulfonate derivatives of calixarene and O-n-hexylcalixarene (1a and 1b, respectively) were synthesized.Measurements using fluorescence and absorption spectral probes indicated that the cavity of calixarene can accept a naphthalene molecule but not pyrene molecule and that (1b) has a hydrophobic cavity constructed from the aggregate of the hexyl groups while (1a) provides a reaction field apparently more polar than water.This is the first example for water-soluble host molecules derived from calixarene.