Properties of composite solid polymer electrolyte using hyperbranched polymer with ether-linkage

The cross-linked composite solid polymer electrolytes composed of poly(ethylene oxide), lithium salt (LiN(SO₂CF₃)₂), and a hyperbranched polymer whose repeating units were connected by ether-linkage (hyperbranched polymer (HBP)-2) were prepared, and their ionic conductivity, thermal properties, electrochemical stability, mechanical property, and chemical stability were investigated in comparison with the non-cross-linked or cross-linked composite solid polymer electrolytes using hyperbranched polymers whose repeating units were connected by ester-linkage (HBP-1a, 1b). The cross-linked composite solid polymer electrolyte using HBP-2 exhibited higher ionic conductivity than the non-cross-linked and cross-linked composite solid polymer electrolytes using HBP-1a and HBP-1b, respectively. The structure of the hyperbranched polymer did not have a significant effect on the thermal properties and electrochemical stability of the composite solid polymer electrolytes. The tensile strength of the cross-linked composite solid polymer electrolyte using HBP-2 was lower than that of the cross-linked composite solid polymer electrolyte using HBP-1b, but higher than that of the non-cross-linked composite solid polymer electrolyte using HBP-1a. The HBP-2 with ether-linkage showed higher chemical stability against alkaline hydrolysis compared with HBP-1a with ester-linkage.     

Fluorescence Energy Transfer Study of Interstrand DNA Cross-linking Caused by Rigid Bisintercalator

The intermolecular cross-linking of DNA with a rigid bisintercalator, 1,4-bis(( N -methylquinolinium-4-yl)vinyl)benzene (pMQVB) has been studied using fluorescence resonance energy transfer (FRET), fluorescence anisotropy measurements, and dynamic fluorescence microscopy. Short DNA duplexes, single-labeled with fluorescein (donor) and x-rhodamine (acceptor), were used as energy transfer partners. Due to the quenching effect of pMQVB on the emission of both fluorescein and x-rhodamine, the energy transfer was monitored using the corrected Stern-Volmer plots. The cross-linking ability of pMQVB depended on the ligand structure; the planar E , E isomer cross-linked DNA contrary to the non-planar E , Z isomer. Dynamic fluorescence microscopy observation also demonstrated the ability of pMQVB to cross-link large T4 DNA molecules.     

Host–guest supramolecular polymers constructed of aniline derivatives and three-dimensional coordination polymers [(n-Bu3Sn)2(R3Sn)Fe(CN)6] n,R = n-Bu or Ph

The straightforward self-assembly reaction of R₃Sn⁺ and [Fe(CN)₆]^3? affords three-dimensional (3-D) coordination polymers [(n-Bu₃Sn)₂(R₃Sn)Fe(CN)₆] _n , R = n-Bu(I) or Ph(II). The architecture of these coordination polymers is closely related to zeolite and acts as a host with wide internal cavities or channels capable of encapsulating voluminous organic compounds. Aniline derivatives acting as guest are encapsulated within the cavities of the 3-D-polymeric hosts I and II by tribochemical reaction producing host–guest supramolecular polymers. The structures and physical properties of these hosts and their host–guest systems were investigated by elemental analysis, X-ray powder diffraction, IR, UV-vis, EPR, and magnetic measurements. The morphology of these systems was examined by scanning electron microscopy (SEM). The interesting feature of these host–guest supramolecular polymers is the enhanced electrical conductivities over those of the 3-D-coordination polymeric hosts upon encapsulation of conductive polymers within their cavities.     

The Development of Polybenzimidazole Composites as Ablative Heat Shields

Abstract

The excellent high-temperature mechanical properties and other desirable characteristics of polybenzimidazole (PBI) polymer systems make these systems attractive candidates for development as ablative heat-shield materials. This paper describes the formulation of several new low-density polybenzimidazole composites. The proposed structure of the basic linear PBI prepolymer and of several highly cross-linked PBI polymers are presented. The cross-linked PBI's were obtained either thermally (by postcuring to a high temperature) or chemically (by the use of either preoxidized polyfunctional amines or triphenyl trimeasate as a comonomer in the polymerization).     

Construction of Supramolecular Polymers with Different Topologies by Orthogonal Self-Assembly of Cryptand–Paraquat Recognition and Metal Coordination

Recently, metal-coordinated orthogonal self-assembly has been used as a feasible and efficient method in the construction of polymeric materials, which can also provide supramolecular self-assembly complexes with different topologies. Herein, a cryptand with a rigid pyridyl group on the third arm derived from BMP32C10 was synthesized. Through coordination-driven self-assembly with a bidentate organoplatinum(II) acceptor or tetradentate Pd(BF₄)₂•4CH₃CN, a di-cryptand complex and tetra-cryptand complex were prepared, respectively. Subsequently, through the addition of a di-paraquat guest, linear and cross-linked supramolecular polymers were constructed through orthogonal self-assembly, respectively. By comparing their proton nuclear magnetic resonance (¹H NMR) and diffusion-ordered spectroscopy (DOSY) spectra, it was found that the degrees of polymerization were dependent not only on the concentrations of the monomers but also on the topologies of the supramolecular polymers.     

Properties and hydrolysis of PLGA and PLLA cross-linked with electron beam radiation

Radiation has been used as a processing tool to modify the properties of polymers. The aim of this study is to understand how electron beam radiation, together with pentaerythritol tetraacrylate (PTTA) as a tetra-functional monomer, can alter the properties (i.e. thermal and mechanical) and hydrolysis rates of PLGA and PLLA. The effects of radiation dose and PFM concentration on the physical properties of the polymers were investigated. The results showed that upon irradiation PLGA and PLLA cross-linked, and an increased in gel content was observed. Glass transition temperature (T_g) and mechanical properties of the polymers also increased. Cross-linked PLGA and PLLA samples were found to retard hydrolytic degradation. The mechanical properties of these polymers were also unaffected by hydrolysis. In summary, PLGA and PLLA cross-linked with PTTA were found to have enhanced mechanical properties and were able to retard hydrolytic degradation.     

Tuning energy landscapes and metal–metal interactions in supramolecular polymers regulated by coordination geometry

Herein, we exploit coordination geometry as a new tool to regulate the non-covalent interactions, photophysical properties and energy landscape of supramolecular polymers. To this end, we have designed two self-assembled Pt(ii) complexes 1 and 2 that feature an identical aromatic surface, but differ in the coordination and molecular geometry (linear vs. V-shaped) as a result of judicious ligand choice (monodentate pyridine vs. bidentate bipyridine). Even though both complexes form cooperative supramolecular polymers in methylcyclohexane, their supramolecular and photophysical behaviour differ significantly: while the high preorganization of the bipyridine-based complex 1 enables an H-type 1D stacking with short Pt⋯Pt contacts via a two-step consecutive process, the existence of increased steric effects for the pyridyl-based derivative 2 hinders the formation of metal–metal contacts and induces a single aggregation process into large bundles of fibers. Ultimately, this fine control of Pt⋯Pt distances leads to tuneable luminescence—red for 1vs. blue for 2, which highlights the relevance of coordination geometry for the development of functional supramolecular materials.

In this article, we exploit coordination geometry as a new tool to control the energy landscape and photophysical properties (red vs. blue luminescence) of supramolecular polymers.     

Syntheses and structures of Cd(II) and Co(II) compounds of 4-[(3-pyridyl)methylamino]benzoate anion

Three coordination polymers containing Cd(II) and Co(II), connected via 4-[(3-pyridyl)methylamino]benzoate (L^?), have been synthesized in hydrothermal conditions. In [Cd(L)Cl] _n (1), adjacent Cd(II) cations are linked by carboxylates to give a dinuclear cluster. Pairs of L^? bridge the dinuclear cluster to form double helical chains, and these chains are further linked by Cl^? to produce a 4-connected net with (4²?·?6³?·?8) topology. [CdL₂] _n (2) contains 1-D ladder-like chains. The packing structure displays a 3-D supramolecular structure, with π?···?π interactions stabilizing the framework. [CoL₂] _n (3) has a 2-D extended supramolecular structure via π?···?π interactions of 1-D coordination polymers of 3. The crystal structures of 1–3 have been determined by single-crystal X-ray diffraction. Luminescent properties for 1 and 2 are discussed.     

Synthesis and structural characterization of three supramolecular coordination polymers constructed from different metal ions and 2,2′-bipyridyl-3,3′-dicarboxylic acid

Three new supramolecular coordination polymers based on 2,2′-bipyridyl-3,3′-dicarboxylic acid (H₂BPDC) and Mn(II), Fe(II), and Zn(II) were synthesized under hydrothermal conditions and characterized with single-crystallographic X-ray analysis and IR spectrum. Complex 1 exhibits a 1-D, chain-like structure, which is further connected to 2-D supramolecular layer structure through hydrogen bonds. Complex 2 exhibits a 3-D supramolecular structure constructed from 1-D chains through hydrogen bonds and π–π interactions. Like 1, 3 also shows 2-D supramolecular layer structure based on 1-D chains. Furthermore, the fluorescence of 3 was studied.     

Aggregation of two different coordination polymers by reacting zinc nitrate and cadmium chloride with N,N′-ethylenebisacetamide

Two different coordination polymers are obtained from d¹⁰ metal ions [Zn(II) and Cd(II)] and N,N′-ethylenebisacetamide (EBA). {[Zn(EBA)_1.5(NO₃)]?·?(NO₃)} _n (1) is a 1-D coordination polymer assembled from zinc ions and EBA molecules acting as a bridging ligand. Cd(H₂O)₂Cl₂(EBA) (2) is constructed from 1-D inorganic polymeric chains {Cd(OH₂)₂Cl₂} _n and uncoordinated N,N′-ethylenebisacetamide molecules. These chains are interconnected through hydrogen bonds resulting in a 3-D supramolecular network. The luminescent properties of the organic molecule EBA, as well as of the coordination polymers 1, and 2 have been investigated.     

Viologen derivatives with extended π-conjugation structures: From supra-/molecular building blocks to organic porous materials

Recently, increasing attention has been paid on extending the π-conjugation structures of viologens (1,1′-disubstituted-4,4′-bipyridylium salts) by incorporating planar aromatic units into the bipyridinium backbones. Various viologen derivatives with extended π-conjugation structures have been synthesized, including the N-termini aromatic substituted viologens, the extended π-conjugated viologens (denoted as ECVs) as well as the π-conjugated oligomeric viologens (denoted as COVs). These compounds typically exhibit interesting properties distinguished from those of an isolated viologen unit, which make them as new class of electron deficient supra-/molecular building blocks in supramolecular chemistry and materials science. In this review, we would like to highlight the recent advances of viologen derivatives with extended π-conjugation structures in versatile applications ranging from electrochromic and energy storage materials, the ECV/COV-based supramolecular self-assembly systems including the linear supramolecular polymers and 2D/3D supramolecular organic frameworks (SOFs), to the viologen-based covalent organic frameworks (COFs)/networks. We hope this review will serve as an in-time summary worthy of referring, more importantly, to provide inspiration in the rational design of novel molecules with unexplored properties and functions.     

Multipurpose selenophene containing conjugated polymers for optoelectronic applications

In this study, two new conjugated polymers were synthesized including benzotriazole (BTz) as the acceptor unit and selenophene as the π bridge donor segment. These acceptors were coupled with fluorene and carbazole via Suzuki condensation reactions. Electrochemical band gaps were calculated as 2.45 eV for P1 and 2.40 eV for P2. Electrochemical and optical studies of polymers indicate that both polymers are promising candidates for organic solar cell (OSC) and polymer organic light emitting diode (PLED) applications since they have suitable HOMO-LUMO energy levels and appropriate absorption and emission band ranges. Light emitting properties of synthesized polymers were investigated and the highest luminance value was found as 6608cd/m² for P1 at 8 V. Photovoltaic properties of polymers were investigated and the optimized device based on P2 showed 1.75% power conversion efficiency for P2 under AM 1.5 G illumination at 100 mW/cm².     

双光子激发的超分子聚合物纳米颗粒生物成像研究

将具有双-2-脲基-4[1H]-嘧啶酮（bisUPy）的β-二羰基氟硼类衍生物（BF₂-bisUPy）及卟啉衍生物（Por（Pt）-bisUPy）通过四重氢键作用组装成超分子聚合物,通过微乳液法制备成在水中均匀分散的超分子聚合物纳米颗粒（SPNP）。扫描电子显微镜形貌表征表明获得的纳米颗粒粒径约为60 nm。紫外-可见吸收光谱、荧光发射光谱及寿命衰减实验均证明纳米颗粒内BF₂-bisUPy与Por（Pt）-bisUPy可发生高效的能量传递。具有双光子吸收的BF₂-bisUPy作为能量供体,可通过荧光共振能量传递（FRET）增强双光子激发下Por（Pt）-bisUPy的发光。双光子激发荧光强度与激光功率测试表明所制备的超分子聚合物纳米颗粒具有强烈的双光子激发下的荧光及磷光双发射,这种纳米材料可进入细胞,具有优秀的生物相容性,并在双光子激发时表现出强烈的荧光和磷光双发射生物成像。     

Three transition-metal polymers from imidazole dicarboxylates-bearing methoxyphenyl groups: syntheses,crystal structures and properties

Three coordination polymers, namely, {[Cu₂(HMOPhIDC)(4,4′-bipy)]}_n (H₃MOPhIDC = 2-(3-methoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid) (1), [Co(HDMOPhIDC)(phen)]_n (H₃DMOPhIDC = 2-(3,4-dimethoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid) (2) and [Ni₂(HDMOPhIDC)₂(H₂O)₄]_n (3) have been prepared under hydrothermal condition and characterised by elemental analyses, infrared spectroscopy and single-crystal X-ray diffraction. Each of the polymers 1–3 is a 1D column-like structure and displays a 3D supramolecular network via the π…π stacking or hydrogen bond interactions. Furthermore, fluorescence and UV–vis spectroscopic properties of the polymers have been studied.     

Polymers with advanced structural and supramolecular features synthesized through topochemical polymerization

Polymers are an integral part of our daily life. Hence, there are constant efforts towards synthesizing novel polymers with unique properties. As the composition and packing of polymer chains influence polymer''s properties, sophisticated control over the molecular and supramolecular structure of the polymer helps tailor its properties as desired. However, such precise control via conventional solution-state synthesis is challenging. Topochemical polymerization (TP), a solvent- and catalyst-free reaction that occurs under the confinement of a crystal lattice, offers profound control over the molecular structure and supramolecular architecture of a polymer and usually results in ordered polymers. In particular, single-crystal-to-single-crystal (SCSC) TP is advantageous as we can correlate the structure and packing of polymer chains with their properties. By designing molecules appended with suitable reactive moieties and utilizing the principles of supramolecular chemistry to align them in a reactive orientation, the synthesis of higher-dimensional polymers and divergent topologies has been achieved via TP. Though there are a few reviews on TP in the literature, an exclusive review showcasing the topochemical synthesis of polymers with advanced structural features is not available. In this perspective, we present selected examples of the topochemical synthesis of organic polymers with sophisticated structures like ladders, tubular polymers, alternating copolymers, polymer blends, and other interesting topologies. We also detail some strategies adopted for obtaining distinct polymers from the same monomer. Finally, we highlight the main challenges and prospects for developing advanced polymers via TP and inspire future directions in this area.

This perspective showcases the potential of topochemical polymerization as an effective tool for synthesizing polymers with advanced molecular and supramolecular structures.     

Supramolecular isomerism of Cu(I) and 3,5-di-2-pyridyl-1,2,4-triazolate via in situ solvothermal ligand reaction: meso-helix and luminescence

The sixth supramolecular isomer of Cu(I) and 3,5-di-2-pyridyl-1,2,4-triazolate (2-pytz), [Cu₂(2-pytz)₂] _n (1), via in situ solvothermal ligand reaction, has been synthesized and characterized as a rare meso-helical chain. Complex 1 exhibits high thermal stability (until 400°C) confirmed by thermogravimetric analysis and has potential applications as an optical material. This research makes the maximum number of genuine supramolecular isomers with structural characterization, found for coordination polymers, six.     

Fluorescence resonance energy transfer (FRET) in chemistry and biology: Non-F?rster distance dependence of the FRET rate

Fluorescence resonance energy transfer (FRET) is a popular tool to study equilibrium and dynamical properties of polymers and biopolymers in condensed phases and is now widely used in conjunction with single molecule spectroscopy. In the data analysis, one usually employs the F?rster expression which predicts (l/R ⁶) distance dependence of the energy transfer rate. However, critical analysis shows that this e_xpression can be of rather limited validity in many cases. We demonstrate this by explicitly considering a donor-acceptor system, polyfluorene (PF₆)-tetraphenylporphyrin (TPP), where the size of both donor and acceptor is comparable to the distance separating them. In such cases, one may expect much weaker distance (as l/R ² or even weaker) dependence. We have also considered the case of energy transfer from a dye to a nanoparticle. Here we find l/R ⁴ distance dependence at large separations, completely different from F?rster. We also discuss recent application of FRET to study polymer conformational dynamics. Dedicated to Prof J Gopalakrishnan on his 62nd birthday.     

基于一种柔性和角型有机芳香多酸配体的两种3D配位聚合物的合成、结构和荧光性

通过水热合成的方法制得具有三维超分子结构的2种配位聚合物{[Zn（L）（bpa）_0.5（H₂O）₂]·2.25H₂O}_n （1）和{[Cd（L）（H₂O）]·2H₂O}_n （2）,其中,H₃LCl为氯化5-（4-羟基吡啶基甲基）间苯二甲酸,bpa为1,2-二（4-吡啶基）乙烷。这2种化合物的结构通过单晶X射线衍射、红外光谱（IR）、元素分析、热重分析（TG）等方法进行了表征。结构解析表明：化合物1是一种梯型链式结构,并通过链间氢键作用延伸成了3D超分子网络;化合物2为含有大量一维隧道空腔的2D配位网络。此外,研究了这2种化合物的荧光性质。     

Photoluminescence quenching effects of surface-modified gold nanoparticles on side-chain polymers containing pyridyl H-acceptors with various lateral polarities

In this study, we used photoluminescence (PL) quenching and transmission electron microscopy (TEM) to study the morphological behavior of hydrogen-bonded (H-bonded) supramolecular assemblies of luminescent H-acceptor polymers and H-donor gold nanoparticles (Au NPs). In fluorescence titration experiments, the lateral Me and MeO substituents on the fluorescent H-acceptor side-chain polymers PBOT1–PBOT3 and PBT1–PBT3 exhibited different electron-donating capabilities, thereby inducing different degrees of H-bonding and dipole–dipole interactions, as evidenced by effective fluorescence quenching upon the addition of surface-modified Au NPs bearing acid and acid-free surfactants (AuSCOOH and AuSC10, respectively). Among all of our tested nanocomposites, the highest Stern–Volmer quenching constant (K_SV) was that obtained from the assembly of AuSCOOH with the homopolymer PBOT1. In addition, we developed fittable exponential equations to predict the values of K_SV of other fluorescent polymers (containing various molar ratios of pyridyl conjugated units) when titrated with these NP quenchers. The morphologies observed in the TEM images confirmed that fluorescence quenching resulted from the self-assembly of the supramolecular nanocomposites, mediated by H-bonds between the fluorescent H-acceptors of the polymers and the H-donors of the Au NPs presenting acid-modified surfactants.     

基于一种柔性和角型有机芳香多酸配体的两种3D配位聚合物的合成、结构和荧光性

通过水热合成的方法制得具有三维超分子结构的2种配位聚合物{[Zn（L）（bpa）_0.5（H₂O）₂]·2.25H₂O}_n（1）和{[Cd（L）（H₂O）]·2H₂O}_n（2）,其中,H₃LCl为氯化5-（4-羟基吡啶基甲基）间苯二甲酸,bpa为1,2-二（4-吡啶基）乙烷。这2种化合物的结构通过单晶X射线衍射、红外光谱（IR）、元素分析、热重分析（TG）等方法进行了表征。结构解析表明：化合物1是一种梯型链式结构,并通过链间氢键作用延伸成了3D超分子网络;化合物2为含有大量一维隧道空腔的2D配位网络。此外,研究了这2种化合物的荧光性质。