Supramolecular Chirality in Self-Assembled Systems

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Infinite-Dimensional Dynamical Systems in Mechanics and Physics (Roger Temam)

Anion recognition and sensing in organic and aqueous media using luminescent and colorimetric sensors

As an alternative to conventional inorganic intercalation electrode materials, organic electrode materials are promising candidates for the next generation of sustainable and versatile energy storage devices. In this paper we provide an overview of organic electrode materials, including their fundamental knowledge, development history and perspective applications. Based on different organics including n-type, p-type and bipolar, we firstly analyzed their working principles, reaction mechanisms, electrochemical performances, advantages and challenges. To understand the development history and trends in organic electrode materials, we elaborate in detail various organics with different structures, including conducting polymers, organodisulfides, thioethers, nitroxyl radical polymers and conjugated carbonyl compounds. The high electrochemical performance, in addition with the unique features of organics such as flexibility, processability and structure diversity, provide them great perspective in various energy storage devices, including rechargeable Li/Na batteries, supercapacitors, thin film batteries, aqueous rechargeable batteries, redox flow batteries and even all-organic batteries. It is expected that organic electrode materials will show their talents in the “post Li-ion battery” era, towards cheap, green, sustainable and versatile energy storage devices.

Towards sustainable and versatile energy storage devices: an overview of organic electrode materials

Studying nature to reveal the mechanisms of special wetting phenomena in biological systems can effectively inspire the design and fabrication of functional interfacial materials with superwettability. In this Review, the historical development, new phenomena and emerging applications of superwettability systems are discussed.

Nature-inspired superwettability systems

A fundamental and persistent problem in the study of carbonbased electrode materials for lithium ion batteries is the question of how many lithium ions can be inserted onto a C6 aromatic ring. Although different empirical models of Lix/C6 (x< 3) have been proposed, the question remains unresolved. Herein we employ 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), an aromatic compound containing a naphthalene ring system (fused C6 aromatic rings), to demonstrate that each carbon in a C6 ring can accept a Li ion to form a Li6/C6 additive complex through a reversible electrochemical lithium addition reaction. This process results in Li ion insertion capacities of up to nearly 2000 mAhg , depending on the exact molecular structure. This value is several times higher than any other organic electrode material previously reported and can be fully released under certain conditions. Our experiments and theoretical calculations indicate that the anhydride groups on the sides of the aromatic system are crucial for this process, which provides a promising strategy for the design of novel high-performance organic electrode materials. Organic molecules are intriguing candidates for electrode materials for use in rechargeable Li ion batteries. The application of such species has aroused much interest recently, owing to the obvious advantages of such a system: no need for rare metals, low safety risks compared to transition metal oxides, and design flexibility at the molecular level. However, organic molecules are usually considered to possess relatively poor specific energies and cycling properties, as compared to those of inorganic materials, and these factors greatly limit their practical application. Recently, studies on aromatic carbonyl derivatives showed that organic materials can possess outstanding electrochemical performance comparable to, or even superior to, inorganic materials. Furthermore, the wide diversity of organic redox systems, as well as the excellent flexibility in their molecular design, suggest even greater prospects for these materials, and this has inspired the exploration of new organic Li ion insertion systems with improved performance. Aromatic C6 rings are the basic structural units of graphite and other carbon-based electrode materials, which are the most commonly used anodes in commercial Li ion batteries owing to their high electric conductivity and low cost. It has traditionally been believed that each C6 ring can accept one Li ion to form an intercalated Li/C6 complex, giving a relatively low theoretical capacity of 372 mAhg . Recently, studies on graphene, nanographene, and their derivatives reveal that, through the reduction of size and dimensionality, these materials exhibit unique electric and electrochemical properties superior to those of conventional graphitic materials; thus, these materials are currently a hot research topic. In studies of electrode materials for Li ion batteries, these derivatives also exhibit high reversible capacities of up to almost twice the theoretical value of graphite, although the detailed mechanism is still unclear. This leads to a fundamental question in the study of carbonbased electrode materials: How many Li ions can actually be inserted onto each C6 aromatic ring? Multi-ring aromatics (for example, naphthalene, NTCDA, perylene, etc.) and their derivatives have planar C6 ring structures similar to graphene or nanographene. NTCDA is a typical example; it has a naphthalene-like ring structure consisting of two C6 rings fused together along with two cyclic anhydride groups (Figure 1a). NTCDA is a well-known organic semiconductor with good crystallinity and has been extensively studied for use in molecular electric devices. It provides an ideal model to study Li ion insertion onto C6 rings owing to the minimal number of C6 rings it possesses, which guarantees the necessary insolubility of the electrode materials in the commonly used electrolyte solution (ethylene carbonate/dimethyl carbonate/LiPF6) for Li ion batteries. NTCDA also possesses the necessary degree of conductivity for electron transport among molecules. We investigated the electrochemical Li ion insertion/deinsertion properties of NTCDA using model test cells with Li metal as the counter electrode. The working electrode consisted of NTCDA, acetylene black (AB), and polytetrafluoroethylene binders in a weight ratio of about 60:35:5. The cells were initially cycled by discharging (Li ion insertion) and charging (Li ion deinsertion) repeatedly in a potential range of 0.001–3.0 V vs. Li/Li at a moderate current rate of 100 mAg . Figure 1b shows selected discharge/charge curves (the 1st, 2nd, 3rd, and 8th cycles) for NTCDA. Figure 1c shows the corresponding discharge and charge capacities of NTCDA versus the cycle number. The first discharge and charge capacities are 1273 and 724 mAhg , respectively, showing a coulombic efficiency [*] X. Han, G. Qing, T. Sun State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology Wuhan, 430070 (China) E-mail: suntaolei@iccas.ac.cn

How many lithium ions can be inserted onto fused C6 aromatic ring systems

Controlling the interfacial chemical and physical properties, and thus modulating the behaviours of cells and biomolecules on material surfaces, form an important foundation for the development of high-performance biomaterials and devices. Biological systems in nature exhibit unique features in this aspect. The first one is that the superior properties of natural biomaterials are normally not determined by their bulk properties, but more related to the multi-scale micro- and nanostructures on the surface; the second is that biological systems usually utilize highly specific weak interactions (e.g. hydrogen bonding interaction, hydrophobic interaction, etc.) to solve the problems of biomolecule interactions; the third is that the biomolecules in nature are often chiral molecules and show high preference for one specific enantiomorphous configuration, suggesting a distinctive chiral recognition mechanism in biological systems. These features bring much inspiration to design novel biointerface materials with special functionalities, e.g. structural biointerface materials, smart biointerface materials and chiral biointerface materials. The purpose of this critical review is to give a brief introduction of recent advances in these aspects (90 references).

Functional biointerface materials inspired from nature

Controlling the surface chemical and physical properties of materials and modulating the interfacial behaviors of biological entities, e.g., cells and biomolecules, are central tasks in the study of biomaterials. In this context, smart polymer interface materials have recently attracted much interest in biorelated applications and have broad prospects due to the excellent controllability of their surface properties by external stimuli. Among such materials, poly(N-isopropylacrylamide) and its copolymer films are especially attractive due to their reversible hydrogen-bonding-mediated reversible phase transition, which mimics natural biological processes. This platform is promising for tuning surface properties or to introduce novel biofunctionalities via copolymerization with various functional units and/or combination with other materials. Important progress in this field in recent years is highlighted.

Biomimetic Smart Interface Materials for Biological Applications

Chiral phenomena are ubiquitous in nature from macroscopic to microscopic, including the high chirality preference of small biomolecules, special steric conformations of biomacromolecules induced by it, as well as chirality-triggered biological and physiological processes. The introduction of chirality into the study of interface interactions between materials and biological systems leads to the generation of chiral biointerface materials, which provides a new platform for understanding the chiral phenomena in biological system, as well as the development of novel biomaterials and devices. This critical review gives a brief introduction to the recent advances in this field. We start from the fabrication of chiral biointerface materials, and further investigate the stereo-selective interaction between biological systems and chiral interface materials to find out key factors governing the performance of such materials in given conditions, then introduce some special functionalities and potential applications of chiral biointerface materials, and finally present our own thinking about the future development of this area (108 references).

Chiral biointerface materials

Protein misfolding to form amyloid aggregates is the main cause of neurodegenerative diseases. While it has been widely acknowledged that amyloid formation in vivo is highly associated with molecular surfaces, particularly biological membranes, how their intrinsic features, for example, chirality, influence this process still remains unclear. Here we use cysteine enantiomer modified graphene oxide (GO) as a model to show that surface chirality strongly influences this process. We report that R-cysteine modification suppresses the adsorption, nucleation, and fiber elongation processes of Aβ(1–40) and thus largely inhibits amyloid fibril formation on the surface, while S-modification promotes these processes. And surface chirality also greatly influences the conformational transition of Aβ(1–40) from α-helix to β-sheet. More interestingly, we find that this effect is highly related to the distance between chiral moieties and GO surface, and inserting a spacer group of about 1–2 nm between them prevents the ...

Guangyan Qing

Papers

How many lithium ions can be inserted onto fused C6 aromatic ring systems

Functional biointerface materials inspired from nature

Biomimetic Smart Interface Materials for Biological Applications

Chiral biointerface materials

Chiral Effect at Protein/Graphene Interface: A Bioinspired Perspective To Understand Amyloid Formation