Ring‐Opening of Benzocyclobutenol with Mild Bases and Trapping with Dieneophiles

The treatment of benzocyclobutenol with a mild base has been investigated. This reaction results in an electrocyclic opening of the cyclobutene to the corresponding o‐quinodimethane, which has been successfully treated with aldehydes and electron‐deficient alkenes to form benzolactols and benzocyclohexenes respectively.     

Beyond green with synthetic chlorophylls – Connecting structural features with spectral properties

The distinct features of chlorophylls in photosynthesis have led to the formation of numerous derivatives for applications encompassing solar energy conversion, molecular photonics, photodynamic therapy, and molecular imaging. Synthetic chlorins created de novo and bearing a geminal dimethyl group in the reduced ring have proved invaluable for fundamental studies. Four decades of research have led to accumulation of tabulated spectra for > 400 such synthetic chlorins with distinct structural frameworks (17-oxochlorins, 13¹-oxophorbines, chlorinimides) and substituents (alkyl, aryl, ethynyl, phenylethynyl, acetyl, formyl) located at specific (meso, β) positions. In this review, spectral traces (324 absorption, 247 fluorescence) are assembled along with photophysical data including the molar absorption coefficient (ε), fluorescence quantum yield (Φ_f) and singlet excited-state lifetime (τ_s). The review uses the accumulated spectral data derived from chlorins all containing a uniform molecular scaffold to (1) highlight the effects of molecular structure on spectral features, and (2) identify trends including how ε, Φ_f and τ_s vary with wavelength and other features. Use of a common geminal-dimethyl-substituted chlorin scaffold – beginning with no substituents, to one substituent at designated sites, and to 2 or more substituents – provides a systematic Aufbau approach for understanding the absorption spectra of chlorins on a path to and beyond the native chlorophylls. The review provides insights concerning the rational design of potent analogues of Nature’s preeminent red-region absorbers for potential utilization in diverse applications and is aimed at multiple audiences: those interested in spectral properties, tetrapyrrole photophysics, and the molecular design of new chromophores.     

O-phosphorylation of Oligopeptides with Phosphoramidite

Phosphoproteinsplayimportantrolesinbiologicalsignallingcascades,bywhichchemicalsignalsarepassedacrossthecellmembraneandfurthertothecellnucleusl.Forthestudythisprocess,structurallywell-definedpeptidescontainingthecharacteristiclinkageregionofthepeptidebackbonewiththephosphoricacidestercanusedwithmanyadvantages.Ingeneral,estersofoligopeptideswerephosphorylatedwithphosphorylchlorideorwithdialkylordiarylphosphorochloridates'.Butaminogroupsinoligopeptidesshouldbeprotectedwhenhydroxylgroupswerephosp…     

Triclosan-loaded with high encapsulation efficiency into PLA nanoparticles coated with β-cyclodextrin polymer

The purpose was to prepare triclosan-loaded polylactic acid nanoparticles containing β-cyclodextrin polymer shell, evaluate triclosan release from the particles using Franz diffusion cells and to study the stability of the particles in presence of a model protein, bovine serum albumin. The nanoparticles were prepared by a solvent displacement process. The nanoparticles were characterized by their size, encapsulation efficiency and morphology. They were of spherical shape with hydrodynamic diameter of about 100 or 200 nm depending on the polylactic acid used. Their high encapsulation efficiency (~90%) indicated that triclosan is easily incorporated into the nanoparticles. The nanoparticles displayed slow and sustained triclosan release patterns (diffusion coefficient about 10^?22 m²/s) and the β-cyclodextrin polymer coating was stable under simulated physiological conditions. All these data indicated that these novel core–shell nanoparticles might provide a promising carrier system for controlled release of triclosan and other hydrophobic drugs after systemic administration.     

Copolymerization of N-Phenylmaleimide with Cyclohexene

MalebodeanditSderivatvesarewell-bowntopolyInrizetogivethermallystablepolyTnersandthecopolymeriZationwithvariousvinylmonomershasbeenexaminedtohaProvethethermalpropeniesofthepolymers[';-'].HoweverlessworkhasbeendoneonthecopolyInerizationofN-phenylmaletride(PHMI)withcyclohexene(CH).Inthisletter,wesynthesizedanewcopolymerfromthepolymerizahonofPHMIwithCH.ThemonomerPHMIwaspreparedfrommaleicanhydrideandedlineaccordingtoT.OkadaI41.2,2'-Azobisisobutyronitrile(AIBN)wasrecrystallizedtWicefro…     

Cyclopropanation of Diazoacetate with Olefins

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Hybrid supramolecular hydrogels induced by Au nanoparticles protected with MPEG-b-PCL copolymers with α-cyclodextrin

To fabricate supramolecular hydrogel hybridised with well-dispersed gold nanoparticles (AuNPs), water-soluble AuNPs protected with methoxy poly(ethylene glycol)-b-poly(?-caprolactone) (MPEG-b-PCL) self-assembled monolayers (MPEG-b-PCL/AuNPs) were synthesised and used as guest molecules to interact with α-cyclodextrin (α-CD) in aqueous solutions. Transmission electron microscopy measurement results showed that the diameter of the AuNPs produced was about 6–10 nm with a narrow particle size distribution, and stained MPEG-b-PCL/AuNPs micelles made in water clearly displayed the formation of a core-shell structure with a single gold core per micelle. X-ray diffraction measurement results confirmed that there existed the characteristic peaks of both AuNPs and polypseudorotaxanes formed via the inclusion complexation of MPEG-b-PCL moieties with α-CD in as-obtained hydrogels. UV–visible spectra displayed that the same surface plasma resonance absorption peaks appeared at 526 nm for both aqueous dispersion of MPEG-b-PCL/AuNPs and resultant hybrid hydrogel with α-CD. Rheological measurements showed that the hybrid hydrogel has a lower mechanical strength and viscosity, and a relatively prolonged gelation time in comparison with the corresponding native hydrogel. The mechanical strength of the hydrogel nanocomposites could be tailored by modulating the concentration of MPEG-b-PCL/AuNPs and α-CD as well as the composition of MPEG-b-PCL/AuNPs.     

Morphological characterization of metal porphyrin tailed with aspirin interacting with bovine serum albumin congeries

The porphyrins tailed with acetylsalicylic acid (ASA) and Zn (or Cu) complexes were prepared.Meanwhile,morphological images,such as shape and size of porphyrins-BSA congeries were observed by using atomic force microscopy (AFM).The result showed the interaction of BSA and prepared porphyrins led to obvious change of shape and size of BSA congeries.     

A biocatalytic cascade with several output signals—towards biosensors with different levels of confidence

The biocatalytic cascade based on enzyme-catalyzed reactions activated by several biomolecular input signals and producing output signal after each reaction step was developed as an example of a logically reversible information processing system. The model system was designed to mimic the operation of concatenated AND logic gates with optically readable output signals generated at each step of the logic operation. Implications include concurrent bioanalyses and data interpretation for medical diagnostics.

β-Aminovinyl ketonates with heterocyclic fragments

-Aminovinyl ketones containing heterocyclic fragments (tetrahydro-1-6,2-benzothiazine 1,1-dioxide and 2,3-dimethyl-1-phenyl-2,5-dihydro-1H-pyrazole-5-one) (LH) and their complexes with 3d-metals (Co^II, Ni^II, Cu^II, and Zn^II) were synthesized. The obtained ligands give rise to two types of ML₂ chelates with coordinated (coordination number 6; Co, Ni, Zn) and uncoordinated carbonyl group in the pyrazole fragment (coordination number 5; Cu).Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1709–1713.Original Russian Text Copyright © 2004 by Anpilova, Korshunov, Bicherov, Burlov, Borodkin, Zaletov, Uflyand, Garnovskii.This revised version was published online in April 2005 with a corrected cover date.     

DNA Modification with Photochromic Spiro Compounds

The photochromic spiropyrans and spirooxazine having a succinimidyl ester or isothiocyanate pendant group can form covalent products with transaminated DNA.The absorption spectra and solid reflection spectra of modified DNA with these photochromic spiro compounds were investigated.     

Reactions of α-nitroacrylates with thiophenols

Reactions of α-nitroacrylates with aromatic thiols like 4-methyl- and 4-chlorothiophenols afford a series of new 3-arylsulfanyl-2-nitropropanoates. The latter were isolated as diastereomerically pure substances or mixtures of two diastereomers. Structures of the obtained S-adducts were confirmed by IR, ¹H and ¹³C-{¹H} NMR spectroscopy using HMQC and HMBC experiments.     

A Chelate with Conformational Memory?

Coordinated out, pendant in! Exchange of coordinated for pendant amino groups is achieved by the complex cation 1 . The incoming group attacks the concave and convex positions with the same rate and always adopts the same conformation as the leaving group. However, this “conformational memory” is an inexorable consequence of well‐known and dependable concepts: the principle of microscopic reversibility and the induction of chirality in prochiral reagents.     

Complexes of β-cyclodextrin with chloronitrobenzenes and with solvents in water + organic solvent mixtures

Inclusion complexes of chloronitrobenzenes with -cyclodextrin in aqueous 0.1 M phosphate buffer solutions containing various concentrations of ethanol, dimethylsulfoxide, dimethylformamide, acetone and acetonitrile have been studied by a polarographic method. The diffusion coefficients and the stability constants of the corresponding complexes have been determined. Using an equation derived by us which takes account of the change in the cyclodextrin concentration due to the simultaneous complexation of the solvent, both stability constants have been calculated. The influence of solvent on the stability constant of chloronitrobenzenes is discussed     

Transparent conductors from carbon nanotubes LBL-assembled with polymer dopant with π-π electron transfer

Single-walled carbon nanotube (SWNT) and other carbon-based coatings are being considered as replacements for indium tin oxide (ITO). The problems of transparent conductors (TCs) coatings from SWNT and similar materials include poor mechanical properties, high roughness, low temperature resilience, and fast loss of conductivity. The simultaneous realization of these desirable characteristics can be achieved using high structural control of layer-by-layer (LBL) deposition, which is demonstrated by the assembly of hydroethyl cellulose (HOCS) and sulfonated polyetheretherketone (SPEEK)-SWNTs. A new type of SWNT doping based on electron transfer from valence bands of nanotubes to unoccupied levels of SPEEK through π-π interactions was identified for this system. It leads to a conductivity of 1.1 × 10(5) S/m at 66 wt % loadings of SWNT. This is better than other polymer/SWNT composites and translates into surface conductivity of 920 Ω/? and transmittance of 86.7% at 550 nm. The prepared LBL films also revealed unusually high temperature resilience up to 500 °C, and low roughness of 3.5 nm (ITO glass -2.4 nm). Tensile modulus, ultimate strength, and toughness of such coatings are 13 ± 2 GPa, 366 ± 35 MPa, and 8 ± 3 kJ/m(3), respectively, and exceed corresponding parameters of all similar TCs. The cumulative figure of merit, ∏(TC), which included the critical failure strain relevant for flexible electronics, was ∏(TC) = 0.022 and should be compared to ∏(TC) = 0.006 for commercial ITO. Further optimization is possible using stratified nanoscale coatings and improved doping from the macromolecular LBL components.     

Heterocycles with a β-nitroenamine fragment

Reactions of dimedone and dihydroesorcinol with arylidenenitroacetonitriles yield fused 2-amino-3-nitropyrans. The crystal and molecular structure of one of the reaction products was determined by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1142–1145, June, 1999.     

Inclusion complexes of prochiral heterocyclic ketones with β-cyclodextrins and their reduction with sodium borohydride

Alkyl(2-furyl), alkyl(2-thienyl), and methyl pyridyl ketones form stoichiometric inclusion complexes with -cyclodextrins. Reduction of these complexes in aqueous solution of Na₂CO₃ at room temperature yields the corresponding secondary alcohols with an optical yield which attains 27%.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1621–1627, December, 1993.     

Synthesis of Metal Porphyrins Tailed with Salicylic Acid and their Interaction with Bovine Serum Albumin

A synthetic method of porphyrins tailed with salicylic substituents is described.Reaction of bromoalkoxyphenyl porphyrin 1 with salicylic acid gave porphyrins 2-5. These new compounds were confirmed by ^1H NMR, IR, UV-vis, MS and elemental analysis, and observed their interaction with bovine serum albumin (BSA) in fluorescence spectrum.     

Production of Superoxide Ion with Carbon Gas-Diffusion-Electrode And Reaction of Superoxide Ion with Aromatic Halide

Superoxide ion O~-_2 is prepared in aprotic media by carbon gas-diffusion-electrode for the first time. The experimental results indicate that this electrode is superior to carbon plane-electrode in the reaction of O~-_2 with p-bromonitrobenzene. When the gas-diffussion-electrode is used, the yield of the product nitrophenol increases by 20%, and the selectivity of the reaction is nearly doubled as compared with the plane-electrode.