Syntheses, structural properties, and charge-transfer complexes of pyrenophanes

Dithia[3.3](4,9)benzenopyrenophanes carrying various functional groups at the inner position or the outer position of the benzene ring have been prepared. The pyrenophanes with the substituent at the inner position of the opposite benzene ring exhibit the conformation in which the pyrene and the benzene components exist in the parallel manner (parallel conformation). On the contrary the conformation characterized by the perpendicular orientation of the pyrene and the benzene components has been confirmed for the pyrenophanes having the substituent at the outer position of the opposite benzene ring (perpendicular conformation). The NH-pi interaction between the inner amino group on the opposite benzene ring and the pyrene ring was observed. Formation of charge-transfer complexes of the pyrenophanes and tetracyanoethylene (TCNE) was performed. It has been found out that the orientation of two aromatic components and the NH-pi interaction as well as the electronic nature of the substituent on the opposite benzene ring significantly affect characteristics of the charge-transfer complexes in this pyrenophane system.     

Simultaneous construction of polymer backbone and side chains by three‐component polycondensation. Synthesis of polyethers with propargyl side chains from dialdehydes,alkylene bis(trimethylsilyl) ethers,and allenyltrimethylsilane

Polyethers with propargyl side chains were synthesized by the acid‐catalyzed reaction of dialdehydes 1 , alkylene bis(trimethylsilyl) ethers 2 , and allenyltrimethylsilane 4 . When ethylene glycol bis(trimethylsilyl) ether was used as 2 , only oligomer was obtained. However, the use of 2 with longer carbon chains gave the desired polyethers consisting of 1 , 2 , and 4 in the molar ratio 1:1:2 in good yields in the presence of 10 mol % triphenylmethyl perchlorate (TrClO₄) at ?20 °C. This polyether was treated with organometallic reagents such as Co complex or CuCl to give a cross‐linked polymer. This polymer synthesis is unusual in that it concurrently constructs both the polymer backbone and the functional side chains from three starting compounds. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5440–5448, 2005     

Circular DNA by “Bis‐Click” Ligation: Template‐Independent Intramolecular Circularization of Oligonucleotides with Terminal Alkynyl Groups Utilizing Bifunctional Azides

A highly effective and convenient “bis‐click” strategy was developed for the template‐independent circularization of single‐stranded oligonucleotides by employing copper(I)‐assisted azide–alkyne cycloaddition. Terminal triple bonds were incorporated at both ends of linear oligonucleotides. Alkynylated 7‐deaza‐2′‐deoxyadenosine and 2′‐deoxyuridine residues with different side chains were used in solid‐phase synthesis with phosphoramidite chemistry. The bis‐click ligation of linear 9‐ to 36‐mer oligonucleotides with 1,4‐bis(azidomethyl)benzene afforded circular DNA in a simple and selective way; azido modification of the oligonucleotide was not necessary. Short ethynyl side chains were compatible with the circularization of longer oligonucleotides, whereas octadiynyl residues were used for short 9‐mers. Compared with linear duplexes, circular bis‐click constructs exhibit a significantly increased duplex stability over their linear counterparts. The intramolecular bis‐click ligation protocol is not limited to DNA, but may also be suitable for the construction of other macrocycles, such as circular RNAs, peptides, or polysaccharides.     

Synthesis of Highly Substituted Hexahelicenes

C₂‐Symmetric hexahelicenes 3a – 3g , which bear four or six alkoxy chains, were prepared in eight‐to‐nine reaction steps in high overall yields. The final step consisted of a twofold oxidative photocyclization of the corresponding 2,7‐bis(2‐phenylethenyl)naphthalenes. Long (and branched) chains provide a good solubility and processability, which is a prerequisite for applications in organic synthesis and materials science.     

Synthesis of neutral stable polyradicals and their application on photovoltaic devices

Three stable polyradicals with large π-conjugated planar phenalenyl (PLY) radical units as side chain were synthesized. Due to the different conjugated backbones and the interactions between main chains and side chains, these polyradicals and their corresponding precursor polymers presented diverse optical and electrical properties, which were confirmed by UV–vis, fluorescence and CV detections. Besides, they showed excellent solubility in common organic solvents and good stability in the air. Considering their special characteristics, we have fabricated photovoltaic (PV) devices using these polyradicals or polymers as donor material and PCBM as acceptor material. The significant PV performance improvement was observed using a radical-based active layer in the PV devices.     

一种以聚酰亚胺为主链的分子刷合成及表征

以自制的侧基含溴的聚酰亚胺为大分子引发剂,2,2'-联吡啶/氯化亚铜为催化体系,通过原子转移自由基聚合(ATRP)反应,引发甲基丙烯酸三氟乙酯(TFEMA)和甲基丙烯酸2-(三甲基硅氧基)乙酯(HEMA-tms)共聚,制备了以聚酰亚胺为主链的分子刷,聚酰亚胺-接枝-聚(甲基丙烯酸三氟乙酯-共-甲基丙烯酸2-(三甲基硅氧基)乙酯),(PI-g-P(TFEMA-co-HEMA-tms)).对其中甲基丙烯酸2-(三甲基硅氧基)乙酯进行水解得到侧链含羟基的聚酰亚胺分子刷(PI-g-P(TFEMA-co-HEMA)),最后通过羟基与氯磷酸二乙酯反应,得到含亚磷酸酯基团的聚酰亚胺分子刷(PI-g-P(TFEMA-co-HEMA-P)).利用核磁共振氢谱(1H-NMR)、红外等方法,表征了所合成分子刷的结构.利用示差扫描量热法(DSC)、热失重分析(TGA)研究了聚合物分子刷的热性能.根据TGA计算出的分子刷组成与1H-NMR计算结果能较好的吻合.     

Rigid rod polymers with flexible side chains. X. Thermotropic mesophases from aromatic stiff-chain polyamides bearing n-alkoxy side chains

The synthesis of stiff-chain poly(1,4-phenylene terephthalamide)s substituted by two as well as by four flexible side chains per repeating unit is described. The solubility of the materials bearing only two side chains is still very low. Appending of four side chains leads to polyamides which dissolve in common organic solvents. All polyamides reported herein form layered structures in the solid state as well as in the mesophase. Polyamides with two side chains have a very weak tendency for crystallization and do not exhibit a transition to the isotropic state even for the longest side chains. Polyamides with four side chains show three reversible thermal transitions: a disordering transition of the side chains, a transition to a layered, smectic-like mesophase, and finally the transition to an isotropic melt. It is shown that the phase behavior of these materials is mainly governed by the strong segregation of main- and side-chains which can be compared best to the microphase separation in block copolymers. © 1993 John Wiley & Sons, Inc.     

用后功能化方法合成含吲哚二阶非线性光学发色团侧基的高分子

用后功能化方法合成了两类连有吲哚二阶非线性光学发色团侧基的高分子.通过核磁、红外、紫外-可见、示差扫描量热分析、分子量测定等手段对所得高分子进行了鉴定.此合成方法简便易行,易于产物的分离提纯,为二阶非线性光学材料的合成提供了一种新方法.     

Photochromic polymers: effects of structure and environment on photoresponsiveness

In this review paper the photoresponsiveness of photochromic macromolecules under different structural and environmental conditions is discussed with reference to results from the authors' laboratories. Polypeptides, in particular poly(L -glutamic acid) and poly(L -lysine), with spirobenzopyrane side chains show photoinduced conformational variations which are amplified by addition of organic acids or bases to hexafluoro-2-propanol (HFP) solutions. Thus combination of light and environment effects allows modulation of order–disorder conformational transitions. Such photoindiced conformational changes are not observed in the case of macromolecules with a hydrocarbon main chain and azobenzene or stilbene side chains, obtained by polymerization of acrylic monomers. However, even in these systems structural variations affect the dependence of optical properties on irradiation. Moreover, the combination of organic solvents and water shows that polymer solubility can be modulated by light.     

The CA.M lattice revisited. Gel formation from a linear bis-isocyanuric acid and 2-amino-4,6-bis-(4-tert-butylphenylamino)-1,3,5-triazine

Five bis(isocyanuric) acid dimers have been prepared and characterised. The introduction of flexible alkyl chains was necessary to aid solubility. On mixing with N,N-bis(4-tert-butyphenyl)melamine in THF followed by slow evaporation, a viscous gel can form which is interpreted as evidence for the assembly of an infinite 2-D hydrogen bonded network.     

Process intensification of whole-cell biocatalysis with ionic liquids

The unique properties of room temperature ionic liquids such as non-volatility, nonflammability, and, in many cases, high thermal and chemical stability have made them an environmentally attractive alternative to organic solvents. Biphasic biocatalytic processes with nonmiscible liquid phases are usually applied with whole-cell biocatalysts to overcome low water solubility of substrates or products, inhibitory effects of the reactants on the biocatalyst, or low stability of substrates or products in the aqueous phase. The surprising noninvasive effects on cellular membranes of hydrophobic ionic liquids especially of those with hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anions in biphasic ionic liquid/water systems make them superior to many organic solvents so far applied in whole-cell biotransformations. Impressive process intensification in simple biphasic batch processes was recently demonstrated on the examples of asymmetric synthesis with whole-cell biocatalysts, if the distribution coefficients of inhibitory substrates and products between ionic liquids and aqueous phase exceed a log D of about 2 (e.g., ketones and beta-ketoesters with lipophilic side chains and their corresponding chiral alcohols).     

Low-melting salts based on a glycolated cobalt bis(dicarbollide) anion

A new series of low-melting quaternary ammonium salts based on a glycolated cobalt bis(dicarbollide) anion structure have been synthesized and characterized, and their spectroscopic and physicochemical properties have been studied. The lowest melting point was obtained for 1-butyl-3-methylimidazolium (～50 °C) followed by 1-butyl-1-methylpiperidinium (～80 °C), 1-butyl-1-methylpyrrolidinium (～95 °C), and 1-butyl-4-methylpyridinium salts (～115 °C). The salts were thermally stable up to 180 °C [decomposition of an oligo(ethylene glycol) chain] and contained variable amounts of water. The flexible oligo(ethylene glycol) chains contributed to the waxy state of salts. The solubility of the salts was determined for 76 solvents that are commonly used in organic chemistry. Generally, the solubility increased with the dipole moment and relative polarity of the solvent. Salts exhibited good solubility in ketones and esters; moderate solubility was observed in alcohols, aromates, and chlorinated solvents, and poor solubility was obtained in ethers. The salts were practically insoluble in higher hydrocarbons and water. Salts are dissolved in the form of ion pairs or separated ions, depending on the nature of the solvent.     

Shape-persistant macrocycles with terpyridine units: synthesis,characterization, and structure in the crystal

The synthesis of a variety of shape-persistent macrocycles with either one (1a-d, 2) or two (opposing) terpyridine units (3, 4, 5a-c) and inner diameters of up to 2 nm is described. The sequences are mainly based on transition metal cross-coupling reactions and, whenever appropriate, compared with one another regarding their respective efficiency. Typical overall yields and amounts prepared range from 8% (4) to 27% (3) and 25 mg (1a) to 290 mg (1b), respectively. For solubility and processing of the targeted cycles, all precursors have already been decorated with flexible side chains (hexyloxy or hexyloxymethyl). The cycles' characterization is based on MALDI-TOF mass spectrometry, 2D NMR spectroscopy, and/or low-temperature single-crystal X-ray diffraction. Their packing in the crystal is discussed in terms of both number and length of side chains. Cycle 1d was physisorbed into an ordered structure at the solution-HOPG interface and investigated by scanning tunneling microscopy (STM).     

Synthetic receptors for the differentiation of phosphorylated peptides with nanomolar affinities

Artificial ditopic receptors for the differentiation of phosphorylated peptides varying in i+3 amino acid side chains were synthesized, and their binding affinities and selectivities were determined. The synthetic receptors show the highest binding affinities to phosphorylated peptides under physiological conditions (HEPES, pH 7.5, 154 mM NaCl) reported thus far for artificial systems. The tight and selective binding was achieved by high cooperativity of the two binding moieties in the receptor molecules. All receptors interact with phosphorylated serine by bis(ZnII-cyclen) complex coordination and a second binding site recognizing a carboxylate or imidazole amino acid side chain functionality.     

DPD Molecular Simulations of Asphaltene Adsorption on Hydrophilic Substrates: Effects of Polar Groups and Solubility

Adsorption of asphaltenes onto a polar substrate (e.g., a mineral) was modeled with dissipative particle dynamics (DPD) simulations, using continental asphaltene models. The adsorption mechanisms in 10–20% wt, of asphaltene in toluene/ heptane solutions were studied (well above the solubility limit). The structure in the adsorbed layer was highly sensitive to the presence of polar groups in the alkyl side chains and heteroatom content in the aromatic ring structure. Four types of asphaltene models were used: completely apolar (zero adsorption), apolar chains and polar heteroatoms, polar chains and no heteroatoms, and polar chains and heteroatoms (maximum adsorption). One hundred asphaltene monomers were distributed homogeneously in the solvent initially, in a ～(10 nm)³ domain.

Asphaltene monomers adsorbed irreversibly on the substrate via the polar group in the side chains, resulting in an average perpendicular orientation of the aromatic rings relative to the substrate. More frequent π–π stacking of the aromatic rings occurred for less solubility (more heptane), as in aggregates. With apolar side chains, only the heteroatoms in the aromatic ring structure had affinity to the substrate, but the ring plane did not have any preferred direction.

An important finding is that the aromatic ring assemblies “shielded” the substrate and polar groups that were anchored to the substrate, resulting in an effective non-polar surface layer seen by asphaltenes in the bulk, leading to much lower adsorption probability of the remaining asphaltenes. This “adsorption termination” effect leads to mono-layer formation. Continued adsorption with multilayering and reversible nanoaggregate adsorption occurred when both side chains in the model asphaltene (located on opposite sides of the aromatic sheet) contained polar groups, with a higher probability of exposing further polar groups to the bulk asphaltene. The general conclusion is that the number and position of the polar groups in side chains determine to a large degree the adsorption and aggregation behavior/efficiency of (continental) asphaltenes, in line with experimental evidence. The heteroatoms in the aromatic ring structure plays a more passive role in this context, only by providing organization via more π–π stacking in the adsorbed layer, and in aggregates.     

Synthesis of bis-indole carboxamides as G-quadruplex stabilizing and inducing ligands

The design and synthesis of a series of bis‐indole carboxamides with varying amine containing side chains as G‐quadruplex DNA stabilising small molecules are reported. Their interactions with quadruplexes have been evaluated by means of Förster resonance energy transfer (FRET) melting analysis, UV/Vis spectroscopy, circular dichroism spectroscopy and molecular modelling studies. FRET analysis indicates that these ligands exhibit significant selectivity for quadruplex over duplex DNA, and the position of the carboxamide side chains is of paramount importance in G‐quadruplex stabilisation. UV/Vis titration studies reveal that bis‐indole ligands bind tightly to quadruplexes and show a three‐ to fivefold preference for c‐kit2 over h‐telo quadruplex DNA. CD studies revealed that bis‐indole carboxamide with a central pyridine ring induces the formation of a single, antiparallel, conformation of the h‐telo quadruplex in the presence and absence of added salt. The chirality of h‐telo quadruplex was transferred to the achiral ligand (induced CD) and the formation of a preferred atropisomer was observed.     

Molecular brushes with long polyfluorene backbones and polymethacrylic acid side chains: Luminescent properties and self-organization in solutions

A series of molecular brushes with a polyfluorene (PF) backbone and polymethacrylic acid side chains of varying lengths were prepared by atom transfer radical polymerization. The structure and composition of the synthesized compounds were confirmed by ¹H NMR and IR spectroscopy. Effect of the length of the backbone on spectral and conformational parameters of the macromolecules in solutions was analyzed. The grafting density of side chains was about 90%. Spectral methods have been used to determine the dependence of side chain grafting on the luminescent properties of polymer solutions, including quantum yields. It was shown that an optimal length of polymethacrylic acid side chains provides solubility of the polymer brushes. Solutions of PF-graft-polymethacrylic acid complexes with the model substance curcumin were investigated. It was established that the molecular brushes containing curcumin form monomolecular micelles. Molecular brushes with zinc phthalocyanine, potential systems for photodynamic, and photothermal therapy, were studied.     

Poly(Azomethine Sulfones). I. Synthesis and Characterization of New Poly(Azomethine Sulfones) Containing Ortho/Para Aromatic Moieties

Abstract

New poly(azomethine sulfones) with linear structures containing methylene bis(2-oxobenzylidene aniline), methylene bis(4-oxobenzylidene aniline), 1,4-bis(4-oxobenzylidene amino)phenylene and 1,4-bis(2-oxobenzylidene amino)phenylene units were prepared in the conventional literature manner by the reaction of azomethine bisphenols (M 1–4) with 4,4′-sulfonyl bischlorobenzene. The resulting polymers were confirmed by IR, ¹H-NMR and elemental analysis, and were characterized by UV measurements, viscosities, solubilities, DSC and thermo-gravimetric analysis (TGA) in air. A difference in the solubility and thermal behavior between the polymers with ortho- and para- chains was observed. The hydrolitic stability of the polymers in 10% wt aqueous sulfuric acid was reasonable     

Oligo‐ and poly(fullerene)s for photovoltaic applications: Modeled electronic behaviors and synthesis

The atom transfer radical addition polymerization (ATRAP) of fullerene to give poly(fullerene)s (PFs) for organic electronics is explored. Quantum chemistry maps the expected electronic behavior of PFs with respect to common electron acceptors, namely fullerene, phenyl‐C₆₁‐butyric acid methyl ester and its bis‐adduct, and mono‐ and bis‐indine‐fullerene derivatives. Surprisingly, it is found that PFs should demonstrate electron affinities and LUMO energy levels closer to the bis‐derivatives than the mono‐adducts, even though only one C₆₀ double‐bond is used in PF chain formation. A self‐consistent library of PFs is synthesized and a correlation between structural characteristics and molecular weights is found. While comonomers with –OC₁₆H₃₃ linear side‐chains lead to the highest known ATRAP molecular weights of 21000 g mol ^{? 1}, like‐for‐like, branched side‐chains permit syntheses of higher molecular weights and more soluble polymers. Of the series, however, PFs with ‐OC₁₂ side‐chains are expected to be of the greatest interest for opto‐electronic applications due to their ease of handling and highest regioregularity. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1345–1355