Syntheses of novel macrocyclic polyarylate oligomers based on phenolphthalein and m-phthaloyl-dichloride

Novel macrocyclic oligomers were synthesized through the condensation of phenolphthalein and m-phthaloyl-dichloride with triethylamine as catalyst in the mixed solution of methylene chloride and THF via pseudo-high-dilution technique. The oligomers were characterized by IR, H-1 NMR, MS, WAXD, TGA and DSC. It was found that the 3 : 3 adduct (molar ratio of phenolphthalein to m-phthaloyl-dichloride) and the 4 : 4 adduct were the main products and there was a small amount of crystalline in the macrocyclic mixtures. When the mixtures were heated to 360 degrees C, the crystalline disappeared.

Novel macrocyclic aryl thioether ester oligomers: structure characterization and free-radical ring opening polymerization

Novel macrocyclic aryl thioether ester oligomers have been synthesized in high yield from phthaloyl dichloride and 4,4'-thiodiphenol under pseudo high dilution conditions. The cyclic nature was unambiguously confirmed by a combination of MALDI-TOF MS, gel permeation chromatography and NMR analyses. Single-crystal X-ray diffraction of cyclic ester dimer reveals no severe strain on the cyclic structure. The free-radical ring opening polymerization (ROP) of the macrocyclic oligomers was achieved to give high molecular weight polymers via a transthioetherification reaction. The molecular weight of the polymer resulting from ROP decreases as the conversion of cyclic oligomers increases after a polymerization period of 30 min.

Lanthanide binuclear macrocyclic complexes as synthetic enzymes for the cleavage of DNA

Lanthanide binuclear complexes can accelerate the cleavage of pUC19 plasmid DNA, yielding predominantly linear form. The saturation kinetics of the cleavage of pUC19 was studied. The observed rates with lanthanide binuclear complexes showed the expected increase with the catalyst concentration. The rate of cleavage is greater than that of lanthanide ions alone. (C) 1998 Elsevier Science B.V. All rights reserved.

Synthesis and polymerization of some macrocyclic (arylene ether sulfone) containing cardo groups and macrocyclic (arylene ether ketone sulfone) oligomers

Some novel macrocyclic (arylene ether sulfone) containing cardo groups and (arylene ether ketone sulfone) oligomers have been synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-difluorophenylsulfone with bisphenols in the presence of anhydrous potassium carbonate under a pseudo-high-dilution condition. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), fast atom bombardment mass spectrometry (f.a.b.-m.s.), nuclear magnetic resonance spectrometry (n.m.r.) and single-crystal X-ray structure analysis confirms their cyclic nature, and the composition of the oligomeric mixtures is provided by g.p.c. analysis. Ring polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 59.1 k was achieved by heating at 290 degrees C for 40 min in the presence of a nucleophilic initiator. (C) 1998 Elsevier Science Ltd. All rights reserved.

Macrocyclic oligomeric arylene ether ketones: Synthesis and polymerization

Some novel macrocylic(arylene ether ketone)oligomers were synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-dinitrobenzophenone with bisphenols in the presence of anhydrous potassium carbonate under pseudo-high-dilution conditions. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), H-1 NMR and FT-IR confirmed their cyclic nature and the compositions of the oligomeric mixtures was indicated by GPC analysis. Ring-opening polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 52.3 and M-n of 17.2 k was achieved by heating at 280 degrees C for 40 min in the presence of a nucleophilic initiator.

The oxidative demethylation of 24-membered hexa-aza macrocyclic bicopper(I) complex - The mimicking for monooxygenase

By [2 + 2] Schiff base condensation of 5 - bromo - 2 - methoxylbenzene - 1,3 - dicarboxaldehyde with diethylenetriamine, a new hexaaza 24 - membered macrocyclic ligand was obtained,which formed a macrocyclic binuclear copper(I) complex in the presence of [Cu . (CH3CN)(4)]ClO4. When the copper(I) complex was oxidized in air or oxygen, a new macrocyclic binuclear copper( II) complex was obtained. The copper( II.) complex was characterized by several methods and its oxidized products was characterized by H-1 NMR. The results show that during oxidation, a methoxyl group in the ligand ring broke; and the phenoxy - and water - bridged Cu(II) complex formed. In oxidation of monooxygenase such as ligninase, oxidative demethylation also happened. Therefore this work mimicked this process for the first time by using macrocyclic complex. The quantity of absorbed oxygen and the absorption rate of oxygen were determined.

A novel rare earth coordination catalyst for polymerization of biodegradable aliphatic lactones and lactides

A novel rare earth coordination system composed of lanthanide trifluoroacetates Ln(CF3COO)(3) (Ln = Y, Yb, Nd, Tm, Ho, La, Pr) and triisobutylaluminium Al(i-Bu)(3) was used as catalyst for the polymerization of epsilon-caprolactone (CL), D,L-lactide (DLLA) and their copolymerization. The influence of temperature, time and catalyst concentration on polymerization yields and molecular weights of the polyesters have been studied. It was shown that the ring-opening polymerization of cyclic esters catalysed by Ln(CF3COO)(3)/Al(i-Bu)(3) has some living character and the molecular weight of the polyester could be controlled by adjusting the molar ratio of monomer to catalyst. The DLLA/CL copolymer was synthesized by sequential addition of monomers and the structure of the copolyester was characterized by GPC, NMR and DSC. (C) 1998 SCI.

Synthesis, structure and ring-opening polymerization of macrocyclic arylates containing phthalic unit

A series of macrocyclic arylate dimers have been selectively synthesized by an interfacial polycondensation of o-phthaloyldichloride with bisphenols. A combination of GPC, FAB-MS, H-1 and C-13 NMR unambiguously confirmed the cyclic nature. Although single-crystal X-ray analysis of two such macrocycles reveals no severe strain on the cyclic structures, these macrocycles can undergo facile melt polymerization to give high molecular weight polyarylates.

Isolation, spectra, structure, and ring-opening polymerization of strained macrocyclic aryl(ether ketone) dimer

Macrocyclic arylene ether ketone dimer was isolated from a mixture of cyclic oligomers obtained by the nucleophilic substitution reaction of bisphenol A and 4,4'-difluorobenzophenone and easily polymerized to high molecular weight linear poly(ether ketone). The cyclic compound was characterized by FTIR, H-1- and C-13-NMR, and single-crystal x-ray diffraction. Analysis of the spectral and crystal structure reveals extreme distortions of he phenyl rings attached to the isopropylidene center and of the turning points of the molecular polygons. The release of the ring strain on ring-opening combined with entropical difference between the linear polymer chain and the more rigid macrocycle at temperatures of polymerization may be the proposed motivating factors in the polymerization of this precursor to high molecular weight poly(ether ketone). (C) 1997 John Wiley & Sons, Inc.

Crystal structure of a Pr-III complex with a novel macrocyclic ligand

The crystal structure of a novel macrocyclic ligand complex of Pr-III, C112H178O52N8S4Pr2, [Pr2L2(HL)(2)(H2O)(6)]. 22H(2)O is reported. The macrocyclic ligand has pendant acetic acid through which the ligand is coordinated to the Pr-III ion. For the dimeric unit, [Pr2L2(HL)(2)(H2O)(6)], two Pr-III ions are connected by two bridging-chelating carboxyl groups and two bridging carboxyl groups of the ligands, and each Pr-III ion is also bonded to a unidentate carboxyl group of the ligand and three water molecules. The dimeric units are bridged by four ligands through their carboxyl groups to form an infinite one-dimensional chain. The coordination number of the Pr-III ion is nine, with a distorted tricapped trigonal prismatic configuration. (C) 1997 Elsevier Science Ltd.

Synthesis, structure, and ring-opening polymerization of macrocyclic aromatic esters: A new route to high-performance polyarylates

A series of macrocyclic arylate dimers have been efficiently synthesized by an interfacial polycondensation of o-phthaloyl dichloride with bisphenols. A combination of GPC, FAB MS, and H-1 and C-13 NMR unambiguously confirmed the cyclic nature. Although single-crystal X-ray analysis of one such macrocycle reveals no severe strain on the cyclic structure, these macrocycles can undergo facile melt polymerization to give high molecular weight polyarylates.

ANODIC-OXIDATION OF HYDRAZINE ON GLASSY-CARBON MODIFIED BY MACROCYCLIC TRANSITION-METAL COMPLEXES .1. COBALT PROTOPORPHYRIN DIMETHYL ESTER MODIFIED ELECTRODE

The electrocatalytic oxidation of hydrazine (N2H4) on a glassy carbon electrode (GC) modified by monolayer and polymer films of cobalt protoporphyrin dimethyl ester (CoPP) has been studied. Both the monolayer and polymer films of CoPP are very active to the anodic oxidation of N2H4. The activity of CoPP for the anodic oxidation of N2H4 is dependent on the pH of the solution, and the thickness of polymerized CoPP film. The oxidation kinetics were examined by methods of cyclic voltammetry, rotating disc electrodes and steady-state polarization measurement.

Effects of ginkgo biloba extract on cation currents in rat ventricular myocytes

Ginkgo biloba extract (GBE), a valuable natural product for cerebral and cardiovascular diseases, is mainly composed of two classes of constituents: terpene lactones (e.g., ginkgolide A and B, bilobalide) and flavone glycosides (e.g., quercetin and kaempferol). Its electrophysiological action in heart is yet unclear. In the present study, using whole-cell patch clamp technique, we investigated electrophysiological effects of GBE on cation channel currents in ventricular myocytes isolated from rat hearts. We found that GBE 0.01-0.1% inhibited significantly the sodium current (I-Na), L-type calcium current (I-Ca) and transient outward potassium current (IKto) in a concentration-dependent manner. Surprisingly, its main ingredients, ginkgolide A (GB A), ginkgolide B (GB B) and bilobalide (GB BA) at 0.1 mM did not exhibit any significant effect on these cation channel currents. These results suggested that GBE is a potent non-selective cation channel modulator in cardiaomyocytes. Other constituents (rather than GB A, GB B and GB BA) might be responsible for the observed inhibitory effects of GBE on cation channels. (C) 2004 Elsevier Inc. All rights reserved.