betadex and pyridine

The intramolecular oxidation of ROCH

Topics: beta-Cyclodextrins; Coordination Complexes; Crystallography, X-Ray; Demethylation; Dimerization; Ferric Compounds; Heme; Molecular Conformation; Oxidation-Reduction; Porphyrins; Pyridines; Spectrophotometry, Ultraviolet; Water

The inclusion complexation behavior of 3-(2-thienyl)-[1,2,3]triazolo[1,5-a] pyridine (TTP) with native β-cyclodextrin and derivatized cyclodextrins was investigated. Stability constants for complexes with 1 : 1 molar ratios were calculated from phase solubility diagrams. The solubilizing efficiency of the TTP inclusion complex is enhanced in the order of DMβCD > HPβCD > βCD. The TTP-DMβCD inclusion complex was further characterized in solution by means of absorption, fluorescence, 2D NMR and molecular modeling methods. The thermodynamic studies indicate that the inclusion of TTP into the cyclodextrin cavity is mainly an enthalpy-driven process. The 2D NMR studies revealed that the thienyl moiety of TTP is inserted into the CD cavity while the triazolopyridine protrudes the primary rim of the DMβCD, which are in good agreement with docking results. The fluorescence titration of TTP by ctDNA suggested that the quenching mechanism is a dynamic quenching procedure resulting from the temperature dependence of the TTP-ctDNA complex. Thermodynamics of the interaction revealed that the positive values of ΔH and ΔS announced that the binding process was primarily driven by hydrophobic forces indicating that TTP interacts with ctDNA by means of the minor groove. These results are in good agreement with docking experiments and iodide experiments which reinforce TTP's interactions in the minor groove.

Topics: Animals; Antineoplastic Agents; beta-Cyclodextrins; Carbohydrate Conformation; Cattle; DNA; Models, Molecular; Pyridines; Spectrum Analysis; Triazoles

Gold nanoparticles (AuNPs) prepared by citrate reduction of aurochloric acid (HAuCl(4)) were functionalized by tris(4-sulfonatophenyl)porphinatoiron(III) (Fe(III)P2) and poly(ethylene glycol) with thiolated arms (PEG-SH). Fe(III)P2 on the AuNP surface existed as its μ-oxo dimer, which was reduced by Na(2)S(2)O(4) to yield monomeric Fe(II)P2. Fe(II)P2-bearing AuNPs were further functionalized through inclusion of two sulfonatophenyl groups of Fe(II)P2 by a per-O-methylated β-cyclodextrin dimer with a pyridine linker (Py3CD) to obtain AuNPs capable of carrying diatomic molecules in the body. The resulting AuNPs (hemoCD-AuNPs) bound O(2) as well as CO in an aqueous solution. Although a noncolloidal 1:1 complex of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(II) and Py3CD injected into the femoral vein of a rat was rapidly excreted in the urine, no excretion was observed with ferric hemoCD-AuNPs, which were gradually accumulated in the spleen and liver of a rat. These results suggest that hemoCD-AuNPs can be used as a carrier of diatomic molecules such as O(2) and CO in vivo.

Topics: Animals; beta-Cyclodextrins; Carbon Monoxide; Gold; Hemoglobins; Metal Nanoparticles; Myoglobin; Oxygen; Polyethylene Glycols; Pyridines; Rats; Solutions; Spectrophotometry, Ultraviolet; Water

Topics: Animals; beta-Cyclodextrins; Carbon Monoxide; Metalloporphyrins; Oxygen; Pyridines; Rats; Spectrophotometry, Ultraviolet

The photophysical properties of the new pyridin-2'-yl-1,2,3-triazole chromophore have been investigated. Spectroscopic experiments and molecular modelling have provided evidence for a photoinduced charge transfer occurring from the triazole group to the pyridine ring. Hepta- and tetrachromophoric systems have been synthesized by covalently linking seven or four chromophores of this kind, respectively, to a beta-cyclodextrin and a calix[4]arene. They exhibit different fluorescence spectra, decays and quantum yields. Special attention has been paid to the binding of cadmium and zinc ions and to the resulting photophysical effects which are various and very different for the grafted beta-cyclodextrin and calix[4]arene systems.

Topics: Absorption; beta-Cyclodextrins; Cadmium; Calixarenes; Color; Fluorescence; Models, Molecular; Phenols; Pyridines; Spectrometry, Fluorescence; Time Factors; Triazoles

A selective and sensitive fluorescent chemosensor (BBOZP-CD) for Fe(3+) was composed of water-soluble beta-cyclodextrins and 2,6-bis(benzoxazolyl)pyridine which was synthesized through the reaction of 2,6-pyridinedicarboxylic acid and o-aminophenol catalyzed by polyphosphoric acid under microwave irradiation. The chemosensor BBOZP-CD for metal ions were carefully investigated by fluorescent quenching in present of metal ions. The result showed BBOZP-CD chemosensor was remarkable fluorescence quenching and a highly selectivity and sensitivity for Fe(3+) in neutral aqueous solution, and the other common metal ions did not notably disturb the detection of Fe(3+). Additionally, the effect of pH to the chemosensor for Fe(3+) was also studied. The result indicated the respond signals of BBOZP-CD to Fe(3+) was stable and hardly influenced while the pH value was greater than 3.6.

Topics: Benzoxazoles; beta-Cyclodextrins; Fluorescence; Hydrogen-Ion Concentration; Iron; Metals; Pyridines; Solutions; Spectrometry, Fluorescence

Two simple interfaces were designed and realized, enabling on-line coupling of microfluidics reactor chips to a nanoflow electrospray ionization (NESI) time-of-flight (TOF) mass spectrometer (MS). The interfaces are based on two different approaches: a monolithically integrated design, in which ionization is assisted by on-chip gas nebulization, and a modular approach implying the use of commercially available Picospray tips. Using reserpine as a reference compound in a 1ratio1 mixture of acetonitrile and water revealed that both interfaces provide a remarkably stable mass spectrometric signal (standard deviations lower than 8% and 1% for the monolithic and modular approaches, respectively). Glass microreactors, containing mixing zones, were fabricated and coupled to the modular interface with perfluoroelastomer Nanoport fluidics connectors, providing a tool to study chemical reactions on-line. Investigation of the mixing dynamics showed that complete on-chip reagents mixing is achieved within a few tens of milliseconds. Metal-ligand interactions of Zn-porphyrin with pyridine (2), 4-ethylpyridine (3), 4-phenylpyridine (4), N-methylimidazole (5), and N-butylimidazole (6) in acetonitrile as well as host-guest complexations of beta-cyclodextrin (7) with N-(1-adamantyl)acetamide (8) or 4-tert-butylacetanilide (9) in water were studied by mass spectrometry using the modular NESI-chip interface. From on-chip dilution-based mass spectrometric titrations of Zn-porphyrin 1 with pyridine (2) or 4-phenylpyridine (4) in acetonitrile Ka-values of 4.6 +/- 0.4 x 10(3) M(-1) and 6.5 +/- 1.2 x 10(3) M(-1), respectively, were calculated. The Ka-values are about four times larger than those obtained with UV/vis spectroscopy in solution, probably due to a higher ionization efficiency of complexed compared to uncomplexed Zn-porphyrin. For the complexation of N-(1-adamantyl)acetamide (8) with beta-cyclodextrin (7), a Ka-value of 3.6 +/- 0.3 x 10(4) M(-1) was obtained, which is in good agreement with that determined by microcalorimetry.

Topics: Acetanilides; Acetonitriles; Amantadine; beta-Cyclodextrins; Calorimetry; Electrophoresis, Capillary; Electrophoresis, Microchip; Gases; Imidazoles; Ions; Kinetics; Ligands; Mass Spectrometry; Metals; Microfluidic Analytical Techniques; Microscopy, Fluorescence; Models, Chemical; Nanotechnology; Porphyrins; Protein Array Analysis; Pyridines; Reserpine; Software; Spectrometry, Mass, Electrospray Ionization; Time Factors; Water; Zinc

Four different poly(pyridine) complexes of ruthenium, viz. Ru(II)(trpy)(phen)(OH(2))](2+) (1), trans-[Ru(III)(2,2'bpy)(2)(OH(2))(OH)](2+) (2), [(2,2'bpy)(2)(OH)Ru(III)ORu(III)(OH)(2,2'bpy)(2)](4+) (3), and [Ru(II)(4,4'bpy)(NH(3))(5)](2+) (4) (2,2'bpy=2,2'-bipyridine, 4,4'bpy=4,4'-bipyridine, trpy=2,2',2"-terpyridine, phen=1,10-phenanthroline), were tested as non-physiological charge mediators of 'second-generation' glucose biosensors. The membranes for these biosensors were prepared by casting anionic carboxymethylated beta-cyclodextrin polymer films (beta-CDPA) directly onto the Pt or glassy carbon (GC) disk electrodes. Simultaneously, glucose oxidase (GOD) was immobilized in the films by covalent bonding and the Ru complexes were incorporated both by inclusion in the beta-CD molecular cavities and by ion exchange at the fixed carboxymethyl cation-exchange sites. The leakage of the mediator from the polymer has been minimized by adopting a suitable pre-treatment procedure. The biosensors catalytic activities increased in the order 1<2<3<4, as established by linear sweep voltammetry. In case of complexes 2-4, the enzymatic glucose oxidation was mediated by the Ru complexes at their redox potentials. However, this oxidation was mediated by oxygen in case of complex 1 where H(2)O(2) was detected as the reaction product. The effectiveness of the mediators used in the presence of oxygen has been estimated using Pt and GC supports. The redox potential of the mediator does not depend on the support used, while the oxidation of H(2)O(2) proceeds on GC at much higher positive potentials than on Pt. The sensitivity and the linear concentration range of the biosensor studied varied significantly. For complex 4, which forms stable inclusion complex with beta-CD, the biosensor sensitivity was the highest and equal to 7.2 micro A mM(-1) cm(-2), detectability was as low as 1 mM, but the linear concentration range was limited only to 4 mM. In contrast, for complexes 2 and 3 the sensitivity was 0.4 and 3.2 micro A mM(-1) cm(-2), while the linear concentration range extended up to at least 24 and 14 mM glucose, respectively. Even though some common interfering substances, such as ascorbate, paracetamol or urea, are oxidized at potentials close to those of the Ru complex redox couples, their electro-oxidation currents at physiological concentrations are insignificant compared to those due to the biocatalytic oxidation of glucose. The biosensor response to glucose is revers

Topics: beta-Cyclodextrins; Biosensing Techniques; Cyclodextrins; Enzymes, Immobilized; Glucose; Glucose Oxidase; Membranes, Artificial; Oxidation-Reduction; Polymers; Pyridines; Ruthenium Compounds