Cyclic Tetramers of Zinc Chlorophylls as a Coupled Light‐Harvesting Antenna–Charge‐Separation System

A coupled light‐harvesting antenna–charge‐separation system, consisting of self‐assembled zinc chlorophyll derivatives that incorporate an electron‐accepting unit, is reported. The cyclic tetramers that incorporated an electron acceptor were constructed by the co‐assembly of a pyridine‐appended zinc chlorophyll derivative, ZnPy , and a zinc chlorophyll derivative further decorated with a fullerene unit, ZnPyC₆₀ . Comprehensive steady‐state and time‐resolved spectroscopic studies were conducted for the individual tetramers of ZnPy and ZnPyC₆₀ as well as their co‐tetramers. Intra‐assembly singlet energy transfer was confirmed by singlet–singlet annihilation in the ZnPy tetramer. Electron transfer from the singlet chlorin unit to the fullerene unit was clearly demonstrated by the transient absorption of the fullerene radical anion in the ZnPyC₆₀ tetramer. Finally, with the co‐tetramer, a coupled light‐harvesting and charge‐separation system with practically 100 % quantum efficiency was demonstrated.     

Novel fluorescent liquid crystals: synthesis,mesomorphism and fluorescence of triphenylene-Bodipy derivatives based on 1,3,5-triazine core

The novel triphenylene-Bodipy derivatives 6 and 7 based on 1,3,5-triazine core were designed and synthesised by introducing BODIPY unit and triphenylene units sequentially onto cyanuric chloride. The Bodipy derivative 6 with one triphenylene unit was a nematic liquid crystal but the derivative 7 with two triphenylene units was a hexagonal columnar liquid crystal. The investigation on photophysical properties suggested that both of them exhibited excellent fluorescence with high fluorescence quantum yields and the Stokes shifts were larger than their Bodipy precursors. This research presented a good example of design and synthesis of columnar Bodipy liquid crystal with high fluorescence and large Stokes shift.     

Synthesis of a partially benzylated derivative of the anhydro-d-altro-heptulose found in Coriaria japonica A

A partially benzylated derivative of the anhydro-d-altro-heptulose found in Coriaria japonica A, which is a synthetically useful unit, was successfully synthesized from a d-mannose derivative by a novel synthetic approach involving an intramolecular O-ketopyranosylation.     

新型含二茂铁基螺苝嗪类光致变色化合物的合成及其光谱研究

合成了一种新的含二茂铁基螺 嗪类光致变色化合物 ,并研究了其吸收光谱和荧光光谱。发现在分子内引入二茂铁基团提高了热不可逆性 ,发生光致变色反应前后化合物结构的不同对其荧光特性影响很大     

Fluoranthene and its π-extended diimides: Construction of new electron acceptors

3,4,8,9-Fluoranthenetetracarboxylic diimides (FDI) are first synthesized as stable yellow compounds by the Diels-Alder (DA) reaction of maleic anhydride and acecyclone derivative bearing an acenaphthylene imide unit and subsequent imidations. An X-ray crystallographic analysis of di(N-octyl)FDI derivative reveals the planar fluoranthene diimide π -system. The cyclic voltammograms of FDIs shows considerably high electron affinity. Moreover, its π -extended analogue involving an anthracene unit (DAAI) was also prepared by the DA reaction of acenaphthylene-3,4-dicarboxylic imide with o-xylylene derivative. The compound exhibits long wavelength absorption and intense fluorescence with moderate solvatofluorochromism (Δλ_EM?=?41?nm). Theoretical calculations based on density function theory (DFT) were performed to characterize the electronic feature of these diimides.     

Regioselective construction of polysubstituted benzene ring from Baylis-Hillman adduct via [4+2] annulation strategy

A new and regioselective [4+2] benzannulation protocol toward polysubstituted benzenes was developed. Nitroalkane derivative, which was prepared from Baylis-Hillman adduct, served as the four-carbon unit and Michael acceptor as a two-carbon unit.     

Preparation and chromatographic evaluation of β-cyclodextrin derivative CSPs bearing substituted phenylcarbamate groups for HPLC

Five β-cyclodextrin (β-CD) derivatives bearing substituted phenylcarbamate/3-(triethoxysilyl)propylcarbamate groups at the 2-, 3-, and 6-positions of glucose unit and another five derivatives containing benzoate at the 2-position and substituted phenylcarbamate/3-(triethoxysilyl)propylcarbamate groups at the 3- and 6-positions were synthesized using the regioselective esterification method. The obtained β-CD derivatives were efficiently immobilized onto the silica gel through the intermolecular polycondensation of a small amount of the triethoxysilyl groups, which were used as the chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). The chiral separation properties of these CSPs were evaluated under the normal-phase HPLC. The effects of solvent polarity and the side chain structures of β-CD derivatives on the chiral recognition ability of the immobilized CSPs were investigated. Among these β-CD derivative CSPs, 2,3,6-tris(3,5-dichlorophenylcarbamate)-β-CD CSP showed a relatively high chiral recognition ability for the studied racemates. The regioselective esterification at the 2-position of glucose unit in the β-CD decreased the chiral recognition ability at the same conditions. For some racemates, the β-CD derivative CSPs showed chiral recognition abilities comparable or better to some chemical bonded β-CD derivative CSPs and 3,5-dichloro- and 3,5-dimethylphenylcarbamates of cellulose and amylose CSPs.     

Liquid-crystalline [60]fullerene-TTF dyads

[structure: see text] [60]Fullerene was functionalized with a TTF derivative and a bis-mesogenic fragment. The synthetic methodology was based on the addition of a malonate derivative to C60 (Bingel-type reaction). Both the malonate and dyad showed smectic B and A phases. The supramolecular organization within the smectic layers was of the monolayer type for the malonate and of the bilayer type for the fullerene derivative. In the latter case, the supramolecular organization was governed by the C60 unit.     

Constituents from the bark of Tabebuia impetiginosa

Thirteen new phenolic glycosides were obtained by further study of constituents from the bark of Tabebuia impetiginosa (MART. ex DC) Standley (Bignoniaceae). The structures of these compounds were determined based on NMR, mass spectral and chemical evidence. Most of them have a glycosyl unit esterified by a benzoic acid derivative.     

Regioselective synthesis of polysubstituted benzenes from Baylis-Hillman adducts via [4+2] annulation protocol

A new and regioselective [4+2] benzannulation protocol toward polysubstituted benzenes was developed. A nitroalkane derivative, which was prepared from Baylis-Hillman adduct, served as the four-carbon unit and a Michael acceptor as a two-carbon unit. Vinyltriphenylphosphonium salt could also be used as a Michael acceptor efficiently.     

Biomimetic synthesis of the pyrrolobenzoxazine core of paeciloxazine

Starting from a protected L-tryptophan derivative the pyrrolobenzoxazine core unit of paeciloxazine can be synthesized in two oxidation steps.     

A new fluorescence probe based on diarylethene with a benzothiazine unit for selective detection of Cd2+

A novel photochromic diarylethene derivative containing a benzothiazine unit has been synthesized. Its photochromism and fluorescent selectivity to metal ions were studied in detail in methanol solution. Under the stimulation of Cd²⁺ ions, the derivative showed a significant fluorescence enhancement and obvious red shift, accompanied by the fluorescent color changed from dark purple to bright blue. The 1: 1 stoichiometry between the derivative and Cd²⁺ was verified by titration experiments and high resolution mass spectrometry. In addition, a molecular logic circuit was designed with the emission intensity at 476?nm as output and the stimuli of Cd²⁺/EDTA and UV/vis as inputs.     

Surface-functionalized fluorescent silica nanoparticles for the detection of ATP

The design of two-dyed fluorescent silica nanoparticles for ATP detection is presented. The indicator dye possesses a dipicolyl-amine (DPA) unit complexed with Zn(II) as a receptor function for ATP while a rhodamine derivative is used as the reference dye. The nanoparticles were fully characterized regarding analytical performance, morphology and cytocompatibility.     

COMMUNICATION: New derivatives of ethyl cellulose

Triethylamine-mediated carboxymethylation of ethyl cellulose using monochloroacetic acid produced a hydroxymethyl acetate derivative (I). The derivative (I) was subsequently converted to a phthalimidoethyl-ethyl cellulose ether derivative by reacting it with β-hydroxyethyl phthalimide using concentrated sulphuric acid as the catalyst. The elemental analysis agreed with the calculated values using an anhydroglucose unit formula that incorporates the degree of substitution. Mechanisms for the formation of these derivatives are proposed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Total synthesis of (+)-tubelactomicin A. 1. Stereoselective synthesis of the lower-half segment by an intramolecular Diels-Alder approach

[reaction: see text]. Starting from diethyl (R)-malate, synthesis of the lower-half segment of (+)-tubelactomicin A, a 16-membered macrolide antibiotic, has been achieved. The synthesis involved the highly endo- and pi-facial selective intramolecular Diels-Alder reaction achieved using a trisubstituted methacrolein derivative tethering a 10-carbon dienyne unit at the beta-carbon, which in turn was prepared from a known allylated malic acid derivative.     

Syntheses of a partially benzylated derivative of the anhydro-d-altro-heptulose found in Coriaria japonica A and of its analogs

A partially benzylated derivative of anhydro-d-altro-heptulose found in Coriaria japonica A, which is a synthetically useful unit, was successfully synthesized from a d-mannose derivative by a novel synthetic approach involving the intramolecular O-ketopyranosylation reaction developed by us. This synthetic approach was also applicable to the preparation of its four analogs.     

Construction of supramolecular polymers with alternating alpha-, beta-cyclodextrin units using conformational change induced by competitive guests

Supramolecular polymers having alternating alpha- and beta-cyclodextrin (CD) units have been prepared by using conformational change induced by competitive guests. Although each CD unit does not form intermolecular complexes, a mixture of an alpha-CD derivative and a beta-CD derivative formed intermolecular complexes to give supramolecular polymers having alternating CD units. This is the first example of construction of supramolecular polymers with alternating alpha-, beta-cyclodextrin units.     

Reductive PET-fragmentation-cyclization processes of bicyclo[n.3.0]alkanones: synthesis of angular quasi-triquinane and propellane systems

Bicyclo[3.3.0]octanone and bicyclo[4.3.0]nonanone derivatives with a cyclopropane unit in the α-position and an unsaturated side chain in the γ-position of the carbonyl group undergo fragmentation-cyclization processes leading to quasi-triquinane systems upon reductive photoinduced electron transfer (PET). For example, the new angular triquinane derivative 6 and the new propellane derivative 12 were synthesized in one step from these starting materials in moderate to good yields.     

Synthesis and functionalization of 3,3'-bis(spirodienone)-bridged 2,2'-bithiophene: a new building block for redox-active molecular switching materials

Bithiophene derivatives bridged with a bis(spirodienone) unit were synthesized and characterized. Lithiation of the thiophene rings of an unsubstituted derivative proceeded without decomposition of the bis(spirodienone) skeleton. Palladium-catalyzed cross-coupling reactions (Suzuki-Miyaura, Sonogashira) with bromides afforded a variety of pi-extended derivatives. Bond breaking and formation under redox conditions were observed by cyclic voltammetry.     

The chemical synthesis of a cyclic oligosaccharide derivative with branching

A cyclic oligosaccharide derivative was synthesized by cationic ring-opening polymerization of an anhydrodisaccharide derivative under high vacuum in dichloromethane with 20 mol% of PF₅ as initiator. Analysis of the spectral results showed that the oligomer chain is composed of only 3 glucose units connected by -1,6 linkages with a glucopyranosyl branching unit at C-4 of each sugar residue in the main chain.