Solvent effects on infrared spectra of methyl 4-hydroxybenzoate in pure organic solvents and in ethanol/CCl4 binary solvents

Infrared spectroscopy studies of methyl 4-hydroxybenzoate (MHB) in 17 different organic solvents and in ethanol/CCl4 binary solvent were undertaken to investigate the solvent-solute interactions. The frequencies of carbonyl stretching vibration nu(C=O) of MHB in single solvents were correlated with the solvent acceptor number (AN) and the linear solvation energy relationships (LSER). The assignments of the two bands of nu(C=O) of MHB in alcohols and the single one of that in non-alcoholic solvents were discussed. The shifts of nu(C=O) of MHB in ethanol/CCl4 binary solvents showed that several kinds of solute-solvent hydrogen bonding interactions coexisted in the mixture solvents, with a change in the mole fraction of ethanol in the binary solvents.     

Preparation and proton conductivity of poly(N‐methylbenzimidazole) doped with acid

To increase the solubility and film forming ability of polybenzimidazole (PBI), poly(N‐methylbenzimidazole) (PNMBI) with different degrees of methylation was synthesized. Chemical structure, degree of substitution, and solubility of PNMBI was studied. PNMBI is easier to be doped with acid than PBI. The basicity of PNMBI was improved with the introduction of methyl groups on the imidazole moiety. Effects of methylation degree, H₃PO₄ content and temperature on proton conductivity of PNMBI doped H₃PO₄ was studied. Proton conductivity of H₃PO₄ doped PNMBI‐1.2 membranes increases with increasing doping level. Temperature dependence of proton conductivity of H₃PO₄ doped PNMBI‐1.2 membranes follows the Arrhenius law. With an increase in the degree of substitution, proton conductivity of H₃PO₄ doped PNMBI decreases dramatically. The proton transport mechanism was also discussed. The proton conductivity of PNMBI/H₃PO₄ is mainly contributed by proton hopping or Grotthuss mechanism. Copyright © 2004 John Wiley & Sons, Ltd.     

ETC and Thermal Ligand Substitution in PhCCo3(CO)9 with 2,3-Bis(diphenylphosphino)-N-phenylmaleimide(bppm). X-Ray Diffraction Structure of Co3(CO)6[μ2,η2, η1-C(Ph)(O)](μ2-PPh2)

The reactivity of the bidentate ligand 2,3-bis(diphenylphosphino)-N-phenylmaleimide (bppm) with the tetrahedrane cluster PhCCo₃(CO)₉ under thermolysis and ETC conditions has been studied and found to ultimately give Co₃(CO)₆[μ₂,η²,η¹-C(Ph) ${\text{C}}{\text{ = }}{\text{ = }}{\text{C(PPh}}_{\text{2}} {\text{)C(O)NPhC}}$ (O)](μ₂-PPh₂) as the final product. The intermediate cluster compound PhCCo₃(CO)₇(bppm), which was observed by IR and ³¹P NMR spectroscopies, readily and rapidly transforms into the product cluster under the reactions conditions. The solid-state structure of Co₃(CO)₆[μ₂,η²,η¹-C(Ph)fptt(O)](μ₂-PPh$_{2})$ was unequivocally determined by X-ray crystallography. Co₃(CO)₆[μ₂, η², η¹-C(Ph)Õ(O)](μ₂-PPh₂) crystallizes in the monoclinic space group P2(1)/n, a = 11.825(5) Å, b = 31.20(1) Å, c = 11.831(5) Å, β = 108.720(7)°, V = 4134(7) ų, Z = 4, d _calc = 1.567 Mg/m³; R = 0.0350, R _w = 0.0817 for 4747 observed reflections with I > 2σ(I). The X-ray structure confirms the coupling of the benzylidyne ligand with the bppm ligand in Co₃(CO)₆[μ₂,η²,η¹-C(Ph)Õ(O)](μ₂-PPh₂). The course of the thermolysis reaction is identical to those reactions carried out with the related diphosphine ligands bma and bpcd. The utility of electron-transfer catalysis (ETC) in the preparation of PhCCo₃(CO)₇(bppm) is discussed relative to the reduction potential of the bppm ligand and the tricobalt cluster PhCCo₃(CO)₉.     

三烃基锡肟类化合物的合成及生物活性

共合成了１３个未见文献报道的三烃基锡肟衍生物，测定了它们的＾１ｈ，（＾１３Ｃ，＾１１９Ｓｎ）ＮＭＲ，ＩＲ和ＭＳ。结果表明此类化合物为四配位锡单体结构，生物活性测定结果表明部分化合物同时兼有杀菌、杀螨、除草多种活性。     

Thermally responsive polymeric micellar nanoparticles self-assembled from cholesteryl end-capped random poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide): synthesis, temperature-sensitivity, and morphologies

Cholesteryl end-capped thermally responsive amphiphilic polymers with two different hydrophobic/hydrophilic chain-length ratios were synthesized from the hydroxyl-terminated random poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) and cholesteryl chloroformate. The hydroxyl-terminated precursor polymers with narrow molecular weight distributions were synthesized by free-radical polymerization using 2-hydroxyethanethiol as a chain-transfer agent. The aqueous solutions of the cholesteryl end-capped copolymers exhibited reversible phase transitions at temperatures slightly above human body temperature, with the lower critical solution temperature values being 37.7 and 38.2 degrees C, respectively. The critical micelle concentration values of the two cholesteryl end-capped polymers were 9 and 25 mg/L, respectively. Polymeric micellar nanoparticles were prepared from the amphiphilic polymers using a dialysis method as well as a direct dissolution method. Transmission electron microscope studies showed that the micellar nanoparticles existed in different morphologies, including spherical, star-like, and cuboid shapes. Pyrene as a model hydrophobic compound could be readily encapsulated in these polymeric nanoparticles, at loading levels of 1.0 and 0.8 mg/g for the two cholesteryl end-capped polymers, respectively. The temperature sensitivity and unusual morphology of these novel polymeric nanoparticles would make an interesting drug delivery system.     

An indium(III)–water chain based on an unusual acyclic water pentamer

An in situ reaction under hydro­thermal conditions leads to the formation of the title compound, diaqua­(pyridine‐2‐carboxyl­ato)­(pyridine‐2,6‐dicarboxyl­ato)indium(II) trihydrate, [In(C₆H₄NO₂)(C₇H₃NO₄)(H₂O)₂]·3H₂O, in which the central In^III atom is seven‐coordinated by one pyridine‐2,6‐di­carboxyl­ate ligand, one pyridine‐2‐carboxyl­ate ligand and two water mol­ecules in a penta­gonal–bipyramidal coordination environment. An indium(III)–water chain based on an unusual water pentamer is observed.     

Configuration of MFI-type zeolite interacting with the probe molecule P(CH<Subscript>3</Subscript>)<Subscript>3</Subscript> – a theoretical study

With P(CH₃)₃ as the probe molecule adsorbed on titanium silicalite (TS-1) zeolite, the special and important role of T12 site in MFI-type zeolite was clearly elucidated. There are altogether three active sites present in TS-1 zeolite with Ti at the T12 site. Owing to the preferential adsorption of probe molecules on the first Brönsted acidic site, the Ti12 center will probably fail to show Lewis acidity. The ionic [HP(CH₃)₃]⁺ species can be stabilized by the first or second Brönsted acidic site, with the former energetically favored. The latter was formed through the transfer of the ionic [HP(CH₃)₃]⁺ species from the first to the second Brönsted acidic site.     

Prenylated isoflavones with potential antiproliferative activities from Mappianthus iodoides

Abstract

A phytochemical investigation on the stems of Mappianthus iodoides led to the isolation of a new naturally occurring prenylated isoflavone, mappianthone A (1), together with seven known analogues (2?8). The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparison with data reported in the literature. All isolated compounds were evaluated for their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1?8 showed significant antiproliferative effects against several human cancer cell lines with IC₅₀ values ranging from 0.16 to 12.68?μM.

     

Intramolecular metathesis of a vinyl group with vinylidene C=C double bond in Ru complexes

The cationic complex {[Ru]=C=CHCPh2CH2CH=CH2}BF4 (3a, [Ru] = (eta5-C5H5)(PPh3)2Ru) in solution transforms to {[Ru]=C=CHCH2CPh2CH=CH2}BF4 (4a) via a new metathesis process of the terminal vinyl group with the C=C of the vinylidene group which is confirmed by 13C labeling studies. This transformation is irreversible as revealed by deuteration and decomplexation studies. The cationic complex {[Ru]=C=CHCPh2CH2CMe=CH2}BF4 (3b) undergoes a cyclization process yielding 6b containing a eta2-cyclic allene ligand which is fully characterized by single-crystal X-ray diffraction analysis. Analogous complexes 4a' and 6b' ([Ru] = (eta5-C5H5)(dppe)Ru) containing dppe ligands were similarly obtained from protonation of the corresponding acetylide complexes via formation of vinylidene intermediate. Protonation of the acetylide complex containing a terminal alkynyl group [Ru]-CCCPh2CH2CCH (2c) generates the vinylidene complex {[Ru]=C=CHCPh2CH2CCH}BF4 (3c) which again undergoes an irreversible transformation to give {[Ru]=C=CHCH2CPh2CCH}BF4 (4c) possibly via a pi-coordinated alkynyl complex followed by hydrogen and metal migration. No similar transformation is observed for the analogous dppe complex 3c'. With an extra methylene group, complex {[Ru]=C=CHCPh2CH2CH2CH=CH2}BF4 (3d) and complex {[Ru]=C=CHCPh2CH2Ph}BF4 (3e) are stable. The presence of a gem-diphenylmethylene moiety at the vinylidene ligand with the appropriate terminal vinyl or alkynyl group along with the correct steric environment implements such a novel reactivity in the ruthenium vinylidene complexes.     

A new method for the derivation of exact vibration-rotational kinetic energy operator in internal coordinates

An efficient angular momentum method is presented and used to derive analytic expressions for the vibration-rotational kinetic energy operator of polyatomic molecules.The vibration-rotational kinetic energy operator is expressed in terms of the total angular momentum operator J,the angular momentum operator J and the momentum operator p conjugate to Z in the molecule-fixed frame Not only the method of derivation is simpler than that in the previous work,but also the expressions ot the kinetic energy operators arc more compact.Particularly,the operator is easily applied to different vibrational or rovibrational problems of the polyatomic molecules by variations of matrix elements Gn of a mass-dependent constant symmetric matrix