Synthesis and Liquid Crystalline Properties of 3-Substituted Pentane-2,4-dione, Pyrazole and Isoxazole Derivatives

The γ-substituted β-diketonate 2,4-dioxo-3-pentyl 4-[4-（n-octyloxy）cinnamoyl]oxybenzoate 1 and its pyrazole and isoxazole derivatives （2 and 3 respectively） have been synthesized and characterized by the spectroscopic methods and elemental analysis. The mesogenic properties of these compounds have been studied by polarizing optical microscopy （POM） and differential scanning calorimetry （DSC）. A monotropic nematic mesophase was observed for the β-diketonate 1, in contrast, the pyrazole 2 displays an enantiotropic smectic A and isoxazole 3 exhibits an enantiotropic nematic mesophase. The relationship between the structure and liquid crystalline properties has also been discussed.     

Synthesis of Doubly Ethyl‐Bridged Bis(p‐sulfonatocalix[4]arene) and Its Supramolecular Polymerization with Viologen Dimer

A water‐soluble supramolecular polymer with a high degree of polymerization and viscosity has been constructed based on the strong host–guest interaction between p‐sulfonatocalix[4]arenes (SC4As) and viologen. A homoditopic doubly ethyl‐bridged bis(p‐sulfonatocalix[4]arene) (d‐SC4A) was prepared and its binding behavior towards methyl viologen compared with the singly ethyl‐bridged bis(p‐sulfonatocalix[4]arene) (s‐SC4A) by NMR spectroscopy and isothermal titration calorimetry. By employing a viologen dimer (bisMV⁴⁺) as the homoditopic guest, two linear AA/BB‐type supramolecular polymers, d‐SC4A?bisMV⁴⁺ and s‐SC4A?bisMV⁴⁺, were successfully constructed. Compared with s‐SC4A?bisMV⁴⁺, d‐SC4A?bisMV⁴⁺ shows much higher solubility and viscosity, and has also been characterized by viscosity, diffusion‐ordered NMR spectroscopy, dynamic light scattering, and atomic force microscopy measurements. Furthermore, the polymer is responsive to electrostimulus as viologen is electroactive, which was studied by cyclic voltammetry. This study represents a proof‐of‐principle as the polymer can potentially be applied as a self‐healing and degradable polymeric material.     

Bis‐hydrophilic and functional triblock terpolymers based on polyethers: Synthesis and self‐assembly in solution

A well‐defined triblock terpolymer, poly(ethylene glycol)‐block‐poly(allyl glycidyl ether)‐block‐poly(tert‐butyl glycidyl ether) (PEG‐b‐PAGE‐b‐Pt‐BGE), with a narrow molar mass distribution has been synthesized by sequential living anionic ring‐opening polymerization. Afterward, the PAGE block was modified via thiol‐ene chemistry and different sugar moieties or cysteine as a model compound for peptides could be covalently attached to the polymer backbone. The solution self‐assembly of the obtained bis‐hydrophilic triblock terpolymers in aqueous media has been studied in detail by turbidimetry, dynamic light scattering, and transmission electron microscopy (TEM and cryo‐TEM). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Controlled synthesis of new amphiphilic glycopolymers with liquid crystal grafts

A cholesterol‐based liquid crystal monomer, diethylene glycol cholesteryl ether acrylate (DEGCholA), has been successfully polymerized by atom transfer radical polymerization (ATRP) for the first time. Appropriate experimental conditions to control the polymerization of DEGCholA have been investigated using a model initiator (ethyl 2‐bromoisobutyrate) in tetrahydrofuran (THF) or toluene at 60 °C. Well‐controlled ATRP of DEGCholA was obtained using N,N,N′,N′,N″‐pentamethyldiethylenetriamine as ligand in THF at 60 °C. These conditions were then applied to initiate the ATRP of DEGCholA from multifunctional macroinitiators based on dextran. Using a protection/deprotection synthetic scheme, novel graft glycopolymers (Dex‐g‐PDEGCholA) have been synthesized. The mesomorphic properties of DEGCholA, PDEGCholA, and Dex‐g‐PDEGCholA have been studied by thermal polarizing optical microscopy, differential scanning calorimetry, and X‐ray scattering. PDEGCholA and Dex‐g‐PDEGCholA show an interdigitated smectic A phase (SmA_d) between T_g (～30 °C) and around 170 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3829–3839     

Autoresolution of Segregated and Mixed p‐n Stacks by Stereoselective Supramolecular Polymerization in Solution

A “chirality driven self‐sorting” strategy is introduced for the controlled supramolecular organization of donor (D) and acceptor (A) molecules in multicomponent assemblies. The trans‐1,2‐bis(amido)cyclohexane (trans‐BAC) has been identified as a supramolecular motif with strong homochiral recognition to direct this chirality controlled assembly process of enantiomers in solution. Stereoselective supramolecular polymerization of trans‐BAC appended naphthalene diimide monomers (NDIs) has been probed in detail by spectroscopic and mechanistic investigations. This chirality‐driven self‐sorting design of enantiomeric components also offers to realize mixed and segregated D‐A stacks by supramolecular co‐assembly of the NDI acceptors with trans‐BAC appended dialkoxynaphthalene (DAN) donor monomers. Such an unprecedented chirality control on D‐A organization paves the way for the creation of supramolecular p‐n nanostructures with controlled molecular‐level organization.     

Sulfobetaine‐containing diblock and triblock copolymers via reversible addition‐fragmentation chain transfer polymerization in aqueous media

A novel bifunctional acrylamido‐based reversible addition–fragmentation chain transfer (RAFT) chain‐transfer agent (CTA), N,N′‐ethylenebis[2‐(thiobenzoylthio)propionamide] (CTA2), has been synthesized and used for the controlled free‐radical polymerization of N,N‐dimethylacrylamide (DMA). A comparative study of CTA2 and the monofunctional CTA N,N‐dimethyl‐s‐thiobenzoylthiopropionamide (CTA1) has been conducted. Polymerizations mediated by CTA1 result in poly(N,N‐dimethylacrylamide) (PDMA) homopolymers with unimodal molecular weight distributions, whereas CTA2 yields unimodal, bimodal, and trimodal distributions according to the extent of conversion. The multimodal nature of the PDMAs has been attributed to termination events and/or chains initiated by primary radicals. The RAFT polymerization of DMA with CTA2 also results in a prolonged induction period that may be attributed to the higher local concentration of dithioester functionalities early in the polymerization. A series of ω‐ and α,ω‐dithioester‐capped PDMAs have been prepared in organic media and subsequently employed as macro‐CTAs for the synthesis of diblock and triblock copolymers in aqueous media with the zwitterionic monomer 3‐[2‐(N‐methylacrylamido)‐ethyldimethylammonio] propane sulfonate (MAEDAPS). Additionally, an ω‐dithioester‐capped MAEDAPS homopolymer has been used as a macro‐CTA for the block polymerization of DMA. To our knowledge, this is the first example of a near‐monodisperse, sulfobetaine‐containing block copolymer prepared entirely in aqueous media. The diblock and triblock copolymers form aggregates in pure water that can be dissociated by the addition of salt, as determined by ¹H NMR spectroscopy and dynamic light scattering. In pure water, highly uniform, micellelike aggregates with hydrodynamic diameters of 71–93 nm are formed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1262–1281, 2003     

Iridium(III) Complexes with Sulfonyl and Fluorine Substituents: Synthesis,Stereochemistry and Effect of Functionalisation on their Photophysical Properties

The synthesis and photophysical and electrochemical characterisation of new heteroleptic iridium complexes with electron‐withdrawing sulfonyl groups and fluorine atoms bound to phenylpyridine ligands are reported. The emission energy of these materials strongly depends on the position of the sulfonyl groups and on the number of fluorine substituents. A 90 nm wide tuning range of photoluminescence from the blue‐green (λ_em=468 nm) of iridium(III)bis[2‐(4′‐benzylsulfonyl)phenylpyridinato‐N,C2′][3‐(pentafluorophenyl)‐pyridin‐2‐yl‐1,2,4‐triazolate] to the orange (λ_em=558 nm) of iridium(III)bis[2‐(3′‐benzylsulfonyl)phenylpyridinato‐N,C2′](2,4‐decanedionate) has been achieved. Emission quantum yields ranging from 47 to 71 % have also been found for degassed solutions of the complexes, and a surprisingly high value of 16 % was recorded for iridium(III)bis[2‐(5′‐benzylsulfonyl‐3′,6′‐difluoro)phenylpyridinato‐N,C2′](2,4‐decanedionate) in air‐equilibrated dichloromethane. A unusual stereochemistry of the benzylsulfonyl‐substituted dimer and heteroleptic complexes has been detected by ¹H NMR spectroscopy, and is characterised by the mutual cis disposition of the pyridyl nitrogen atoms of the phenylpyridine ligands, which differs from the most common trans arrangement reported in the literature.     

Synthesis of Z‐Protected Aib‐ and Phe(2Me)‐Containing Pentapeptides and Their Crystal Structures

A series of pentapeptide derivatives containing α,α‐disubstituted α‐amino acids have been prepared by a combination of the ‘azirine/oxazolone method’ and segment condensations. X‐Ray crystal‐structure determinations of the molecular structures confirmed the presence of helical conformations stabilized by β‐turns of type III or III′. Pentapeptides containing (R)‐Phe(2Me) form a right‐handed helix, whereas those containing (S)‐Phe(2Me) adopt a left‐handed helical structure.     

Triazine‐Cored Lanthanide‐Based Metal–Organic Frameworks Featuring Unique Water Chains and Strong Characteristic Emissions

A new triazine‐cored tricarboxylic acid, N,N′,N“‐1,3,5‐triazine‐2,4,6‐triyltris(cis‐4‐aminocyclohexane‐carboxylic acid) (H₃L), has been prepared by replacing the chlorine atoms of cyanuric chloride with cis‐4‐aminocyclohexane‐carboxylic acid, which has been used for the construction of a series of triazine‐cored lanthanide‐based metal–organic frameworks (MOFs). All these MOFs were structurally authenticated, revealing that they are isostructural and exist as two‐dimensional (2D) coordination networks with the general formula [Ln(L)(H₂O)₂]?5.5 H₂O (Ln= 1?Gd , 2?Tb , 3?Eu ). A unique one‐dimensional water chain, composed of primary tetrameric cyclic rings and dodecameric cyclic rings, has been found entrapped in the lattice. Moreover, all these compounds display bright characteristic photoluminescence. Particularly, for 1 , apart from the strong blue emission peak (Φ_f=20.6 %) corresponding to the intraligand transition under near‐UV excitation, the characteristic emissions of Gd³⁺ cation (Φ_f=5.0 %) were unexpectedly observed upon excitation at 273 nm.     

Arylspiroborates Derived from 4‐tert‐Butylcatechol and 3,5‐Di‐tert‐butylcatechol and Their Antimicrobial Activities

A family of arylspiroborates has been prepared by the addition of either 4‐tert‐butylcatechol or 3,5‐di‐tert‐butylcatechol to boric acid and an alkali metal hydroxide. All compounds were characterized fully using multinuclear NMR spectroscopy and by elemental analyses. A single crystal X‐ray diffraction was carried out on potassium (bis‐(3,5‐di‐tertbutyl[1,2‐benzenediolato(2‐)‐O,O′]borate)) ( 8 ). All compounds displayed appreciable anti‐microbial activities.     

从脯氨酸合成一种三齿手性配体及其在二乙基锌对醛的对映选择性加成中的应用

A new chiral tridentate ligand [1-(1-methyl-S-pyrrolidin-2-ylmethyl)-S-pyrrolidin-2-yl]-diphenylmethanol (1) has been successfully synthesized from S-proline. The structure of the ligand was characterized by NMR spectra and X-ray diffraction analysis. Its catalytic ability has also been examined in enantioselective addition of diethylzinc towards aldehydes with 15%-84% enantiomeric excesses (ee).     

Encapsulation and release by star‐shaped block copolymers as unimolecular nanocontainers

A five‐arm star‐shaped poly(ethylene oxide) (PEO) with terminal bromide groups was used as a macroinitiator for the atom transfer radical polymerization of tert‐butyl acrylate (tBA), resulting in five‐arm star‐shaped poly(ethylene oxide)‐block‐poly(tert‐butyl acrylate) block copolymers. The polymerization proceeded in a controlled way using a copper(I)bromide/pentamethyl diethylenetriamine catalytic system in acetonitrile as solvent. The hydrolysis of the tBA blocks of the amphiphilic star‐shaped PEO‐b‐PtBA block copolymer resulted in dihydrophilic star structures. The encapsulation of the star‐block copolymers and their release properties in acid environment have been followed by UV‐spectroscopy and color changes, using the dye methyl orange as a hydrophilic guest molecule. Characterization of the structures has been done by ¹H NMR, size exclusion chromatography, MALDI‐TOF, and differential scanning calorimetry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 650–660, 2008     

Synthesis of 2,4,8‐Trisubstituted 1,7‐Naphthyridines by the Reaction of 4‐(1‐Aryl‐2‐methoxyethenyl)‐3‐isocyanopyridines with Excess Organolithiums

A convenient method for the synthesis of 2,4,8‐trisubstituted 1,7‐naphthyridines 6 by the reaction of (E)‐4‐(1‐aryl‐2‐methoxyethenyl)‐3‐isocyanopyridines 4 , which could be easily prepared from commercially available 3‐aminopyridine via aroylation of lithium (4‐lithiopyridin‐3‐yl)pivalamide with N‐methoxy‐N‐methylbenzamides, with excess organolithiums has been developed.     

New antibacterial cationic surfactants prepared by atom transfer radical polymerization

Efficient antibacterial surfactants have been prepared by the quaternization of the amino groups of poly(ethylene‐co‐butylene)‐b‐poly[2‐(dimethylamino)ethylmethacrylate] (PEB‐b‐PDMAEMA) diblock copolymers by octyl bromide. The diblock copolymers have been synthesized by ATRP of 2‐(dimethylamino)ethylmethacrylate (DMAEMA) initiated by an activated bromide‐end‐capped poly(ethylene‐co‐butylene). In the presence of CuBr, 1,4,7,10,10‐hexamethyl‐triethylenetetramine (HMTETA), and toluene at 50 °C, the initiation is slow in comparison with propagation. This situation has been improved by the substitution of CuCl for CuBr, all the other conditions being the same. Finally, the addition of an excess of CuCl₂ (deactivator) to the CuCl/HMTETA catalyst is very beneficial in making the agreement between the theoretical and experimental number‐average molecular weights excellent. The antibacterial activity of PEB‐b‐PDMAEMA quaternized by octyl bromide has been assessed against bacteria and is comparable to the activity of a commonly used disinfectant, that is, benzalkonium chloride. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1214‐1224, 2006     

Mechanism and Linear Free Energy Relationships in Michael‐Type Addition of 4‐Substituted Anilines to Activated Olefin in Acetonitrile

Kinetic studies for the Michael‐type reactions of ethyl‐3‐(4′‐N,N‐dimethylaminophenyl)‐2‐(nonafluorobutane)sulfonylpro‐penoate 1 with 4‐X‐substituted anilines 2a–e (X = OCH₃, CH₃, H, F, and Cl) have been investigated in acetonitrile at 20°C. A quadratic dependence of the pseudo–first‐order rate constants (k_obsd) versus [ 2a–e ] has been observed and has been interpreted in terms of a dimer nucleophile mechanism. The finding of a relatively large negative ρ value (?3.09) for the Hammett plot suggests that the intermediate ( I^± ) is highly zwitterionic in nature. A linear correlation (r² = 0.9989) between the Hammett's substituent constants σ and nucleophilicity parameters N of 4‐X‐substituted anilines in acetonitrile has been observed. The electrophilicity parameters E of the olefin 1 is evaluated, using the correlations σ versus N and log k versus σ and compared with the electrophilicities of analogously Michael acceptors.     

Regioisomeric Effects on the Electronic Features of Indenothiophene‐Bridged D–π‐A′–A DSSC Sensitizers

Two D–π‐A′–A regioisomers (A‐IDT‐D and D‐IDT‐A) featuring 4,4′‐di‐p‐tolyl‐4 H‐indeno[1,2‐b]‐thiophene as a π linker (π) between the diarylamino donor (D) and the pyrimidine–cyanoacrylic acid acceptor (A′–A) have been successfully synthesized and characterized as efficient sensitizers for the dye‐sensitized solar cells (DSSCs). The different arrangements of the D and A′–A blocks on the unsymmetrical indenothiophene (IDT) core render the dipole of IDT being along (A‐IDT‐D) or opposite (D‐IDT‐A) to the direction of intramolecular (donor‐to‐acceptor) charge transfer, and thus induce variations in the physical properties. The experimental observations correlated well with the theoretical analyses, clearly revealing the trade‐off between the molar extinction coefficient (ε) and the S₀→S₁ transition energy. As a result, a superior ε value was observed for D‐IDT‐A, whereas a bathochromic shift in the absorption occurred in A‐IDT‐D. The larger ε value of D‐IDT‐A together with its more favorable energy level relative to TiO₂ led to a higher power conversion efficiency of 7.41 % for the D‐IDT‐A‐based DSSC, retaining approximately 95 % of the N719‐based DSSC efficiency. This work manifests the clear structure–property relationship for the case of donor and acceptor components being connected by an unsymmetrical π linker and provides insights for molecular engineering of organic sensitizers.     

Synthesis,photopolymerization and adhesive properties of new hydrolytically stable phosphonic acids for dental applications

Novel monomers 2‐(N‐methylacrylamido)ethylphosphonic acid, 6‐(N‐methylacrylamido)hexylphosphonic acid, 10‐(N‐methylacrylamido)decylphosphonic acid, and 4‐(N‐methylacrylamidomethyl)benzylphosphonic acid have been prepared in good yields for use in dental adhesives. They have been fully characterized by ¹H‐NMR, ¹³C‐NMR, ³¹P ‐ NMR, and by HRMS. All monomers are hydrolytically stable in aqueous solution. Free radical homopolymerizations of these monomers have been carried out in solution of ethanol/water (2.5/1:v/v), using 2,2′‐azo(2‐methylpropionamidine) dihydrochloride (AMPAHC) as initiator. They lead to homopolymers in moderate to excellent yields. Structure of the polymers has been confirmed by SEC/MALLS and ¹H‐NMR spectra. The photopolymerization behavior of the synthesized monomers with N,N′‐diethyl‐1,3‐bis(acrylamido)propane has been investigated by DSC. New self‐etch primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on (N‐methylacrylamido)alkylphosphonic acids assure a strong bond between the tooth substance and a dental composite. Moreover, the monomer with the longest spacer group provides the highest shear bond strength. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7074–7090, 2008     

Synthesis of 6‐Aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles by the Cu‐Catalyzed Reaction of 2‐(2‐Bromophenyl)‐1H‐indoles with CH2(CN)2

A series of 6‐aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles 4 have been prepared by treatment of 2‐(2‐bromophenyl)‐1H‐indoles 1 , available from 1‐(2‐bromophenyl)ethanones or 1‐(2‐bromophenyl)propan‐1‐ones by using Fischer indole synthesis, with propanedinitrile in the presence of a catalytic amount of CuBr and an excess of K₂CO₃ in DMSO at 100°.     

Well‐defined polyoxazoline‐based alkoxyamines as efficient macroinitiators in nitroxide‐mediated radical polymerization of styrene

The synthesis of two well‐defined 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐nitroxide‐terminated poly(2‐methyl‐2‐oxazoline) with narrow dispersity (M_w/M_n = 1.1) has been achieved for the first time. The insertion of the alkoxyamine end groups at one or both ends of poly(2‐methyl‐2‐oxazoline) (PMEOX) chains has been successfully done using a method based on “terminating reagent method.” These macroinitiators have molecular weights ranging from 6.3 × 10³ to 9.4 × 10³ g mol^?1. In contrast, attempt to introduce the alkoxyamine group at one end of PMEOX chain through the “initiator method” has furnished a mixture of alkoxyamine‐graft polyoxazolines because of rearrangement of alkoxyamine occurring during the synthesis of PMEOX. The macroinitiators obtained by terminating reagent method have been used successfully for polymerization of styrene by nitroxide‐mediated radical polymerization (NMP), which exhibited all the expected features of a controlled system. The control of NMP has been proved by a good agreement between theoretical and experimental molecular weights and by narrow dispersity (M_w/M_n < 1.2). Different types of well‐defined multiblock copolymers have been prepared: diblock copolymers poly[(2‐methyl‐2‐oxazoline)‐b‐(styrene)] (PMEOX‐b‐PS) and, for the first time, triblock copolymers poly[(styrene)‐b‐(2‐methyl‐2‐oxazoline)‐b‐(styrene)] (PS‐b‐PMEOX‐b‐PS). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1H‐5‐Selena‐1,3,6‐triazaaceanthrylene Derivatives

The reaction of aryl isoselenocyanates 8 with methyl 3‐amino‐4‐chloro‐1‐ethylpyrrolo[3,2‐c]quinoline‐2‐carboxylate ( 6 ) in boiling pyridine leads to tetracyclic selenaheterocycles of type 9 in high yield (Scheme 3). A reaction mechanism via an intermediate selenoureido derivative A and cyclization via nucleophilic substitution of Cl by Se is proposed (Schemes 3 and 5). The reaction of 6 with 4‐bromophenyl isothiocyanate yields the analogous thiaheterocycle 12 (Scheme 4). The molecular structures of 9c and 12 have been established by X‐ray crystallography.