Molecular-scale electronics: From device fabrication to functionality

Device fabrication and functionality are two crucial aspects in molecular-scale electronics. Recent advancesin this field, including fabrication and application of nanogap electrodes, self-assembled monolayers and their functional devicesarehighlighted in this review paper.     

Corannulene derivatives for organic electronics: From molecular engineering to applications

This paper intends to provide an overview for using corannulene derivatives in organic electronics such as organic field-effect transistors (OFETs), organic solar cells (OSCs), and organic light-emitting diodes (OLEDs). We highlight the rational design strategies, tuning molecular orbital energy levels and arrangement in single crystals of corannulenes. The topological structure and properties of corannulene make it a unique candidate for organic electronics.     

Redox polymers in electrochemical systems: From methods of mediation to energy storage

Redox polymers have been an expanding research area over the last 30 years. The design of redox polymers for mediated bioelectrocatalysis revolutionized glucose biosensors in the early 1990s. These concepts were then applied to biofuel cells in the 2000s, but it was not until recently that researchers further translated these concepts to the fields of electrosynthesis, supercapacitors, and redox flow batteries. This review will give a short background to the early work in the field but will primarily discuss the recent applications of the electrosynthesis, supercapacitors, and redox flow batteries.     

Antioxidant and Prooxidant Nanozymes: From Cellular Redox Regulation to Next-Generation Therapeutics

Nanozymes, nanomaterials with enzyme-mimicking activity, have attracted tremendous interest in recent years owing to their ability to replace natural enzymes in various biomedical applications, such as biosensing, therapeutics, drug delivery, and bioimaging. In particular, the nanozymes capable of regulating the cellular redox status by mimicking the antioxidant enzymes in mammalian cells are of great therapeutic significance in oxidative-stress-mediated disorders. As the distinction of physiological oxidative stress (oxidative eustress) and pathological oxidative stress (oxidative distress) occurs at a fine borderline, it is a great challenge to design nanozymes that can differentially sense the two extremes in cells, tissues and organs and mediate appropriate redox chemical reactions. In this Review, we summarize the advances in the development of redox-active nanozymes and their biomedical applications. We primarily highlight the therapeutic significance of the antioxidant and prooxidant nanozymes in various disease model systems, such as cancer, neurodegeneration, and cardiovascular diseases. The future perspectives of this emerging area of research and the challenges associated with the biomedical applications of nanozymes are described.     

Redox monomer ionic liquid based on quaternary ammonium: From electrochemistry to polymer brushes

Bifunctional quaternary ammonium ionic liquid bearing redox and polymerisable units was synthesized. The electrochemical investigations of the ferrocene monomer ionic liquid were performed. Following that, surface-initiated atom transfer radical polymerization (SI-ATRP) was used to build polymer brushes onto the electrode surface. The presence of the Poly(ferrocenyl quaternary ammonium) was evidenced by surface and electrochemical analysis. The latter exhibits high electron transfer rate and the presence of ions within the polymer framework leads to record the attached ferrocenyl redox signal in solution without adding supporting electrolyte. Finally, the wettability of the surface was modulated by electrochemical switch and by anion exchange within the polymer.     

Antithetic function of alcohol in living cationic polymerization: From terminator/inhibitor to useful initiator

We employed alcohols as initiators for living cationic polymerization of vinyl ethers and p‐methoxystyrene, coupled with tolerant Lewis acid, borontrifluoride etherate (BF₃OEt₂), although they were known to be poisonous reagent to bring about chain‐breaking such as chain transfer/termination rather than such beneficial one for propagation and polymerization‐control. As well known, without assistance of additive, ill‐defined polymers with broad molecular weight distributions (MWDs) were produced. Even addition of conventional oxygen‐based bases, for example, ethyl acetate (AcOEt), 1,4‐dioxane (DO), tetrahydrofran (THF), and diethyl ether (Et₂O) was less efficient in this system to control molecular weights and MWDs (M_w/M_n > 2.0). In contrast, by addition of dimethyl sulfide (Me₂S), MWDs of the resultant polymers became much narrower (M_w/M_n < 1.23) and the number‐average molecular weight (M_n) increased in direct proportion to monomer conversion in agreement with the calculated values assuming that one alcohol molecule generates one polymer chain. Studying changed feed‐ratio of alcohol to monomer and structural analyses with NMR and MALDI‐TOF‐MS indicated that quantitative initiation from alcohol giving alkoxide counteranion. This system opens a new way to use a variety of alcohols as initiators, which would allow us to design variety of structures and functions of counteranion. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4194–4201, 2009     

From a spin-crossover molecule to the bulk electronic behaviour of a material: the paramount role of hydrogen bonds in molecular electronics

The exact role of the hydrogen bond network in a spin-crossover material is unambiguously shown: changing the −N-H…O(nitro)salicylidene− ‘communication wire’ between adjacent Fe ions in the unidi-mensional chains of a two-step spin-transition material to the poorer −N-C-H…O(nitro)salicylidene− pathway results in a gradual and partial spin conversion of Fe^II in otherwise similar unidimensional chains of complex molecules. Cooperativity in the spin-crossover phenomenon indeed results from the effectiveness of the inter-molecular communication.     

Abiotic chelators and iron acquisition in living organisms: From molecular iron(III) chelators to self-assembled nanostructures

The story of the highly selective iron(III) chelating agent O-TRENSOX is presented. The promising (and somewhat unexpected in regard to partition coefficients) properties of this molecule induced the development of several tools for iron metabolism studies. The tuning of the properties of O-TRENSOX by chemical modifications of the parent molecules is also developed. Finally, fascinating perspectives are opened by amphiphilic derivatives which mimic marine siderophores from phytoplankton. The self-assembling properties of amphiphilic abiotic chelators and their iron derivatives, as well as the first results concerning iron nutrition of Erwinia chrysanthemi and some mutants, have been studied.     

Discotic liquid crystals: from tailor-made synthesis to plastic electronics

Most associate liquid crystals with their everyday use in laptop computers, mobile phones, digital cameras, and other electronic devices. However, in contrast to their rodlike (calamitic) counterparts, first described in 1907 by Vorl?nder, disklike (discotic, columnar) liquid crystals, which were discovered in 1977 by Chandrasekhar et al., offer further applications as a result of their orientation in the columnar mesophase, making them ideal candidates for molecular wires in various optical and electronic devices such as photocopiers, laser printers, photovoltaic cells, light-emitting diodes, field-effect transistors, and holographic data storage. Beginning with an overview of the various mesophases and characterization methods, this Review will focus on the major classes of columnar mesogens rather than presenting a library of columnar liquid crystals. Emphasis will be given to efficient synthetic procedures, and relevant mesomorphic and physical properties. Finally, some applications and perspectives in materials science and molecular electronics will be discussed.     

Liquid crystals: first active organics in electronics

A Commentary on the paper “Anisotropic gels and plasticized networks formed by liquid crystal molecules”, by R. A. M. Hikmet. First published in Liquid Crystals, 9, 405–416 (1991).     

Liquid crystals: first active organics in electronics

A Commentary on the paper “Anisotropic gels and plasticized networks formed by liquid crystal molecules”, by R. A. M. Hikmet. First published in Liquid Crystals, 9, 405-416 (1991).     

Redox reactions: inconsistencies in their description

The paper is aimed at defining reduction, oxidation, and redox reactions based both on the oxidation number and charge changes in reacting species. It is rationalized that the processes of oxidation and reduction, usually occurring simultaneously, can occur also as independent processes. It is explained that in balancing chemical equations of redox reactions the “gain” or “loss” of electrons should be understood as changes in oxidation number. A formal expressions “+n e^?” and “?n e^?” represent in reality a decrease and increase in oxidation number by n units, respectively.     

A hexa-peri-hexabenzocoronene cyclophane: an addition to the toolbox for molecular electronics

Cyclophanes with the largest-to-date polycyclic aromatic hydrocarbon (hexa-peri-hexabenzocoronene, HBC) to be entrained in such a structural motif are reported. The two disks are covalently captured by intermolecular ring-closing olefin metathesis of dienes in good yield. DSC, optical microscopy, and WAXD show the new cyclophanes to self-assemble to thermotropic columnar liquid crystal mesophases similar to monomeric analogues. Solution spectroscopic studies reveal that the two disks within a single unit lie face-to-face, with a small average lateral offset. Self-assembly into two-dimensional crystals at a solid-liquid interface was visualized by STM, and the electrical properties of single molecules were assessed by scanning tunneling spectroscopy revealing a diode-like behavior which is similar to that previously reported for single HBC disks, laying the groundwork for future electrical interrogations of dynamic molecular complexes.     

Triphenylamine-based electroactive compounds: synthesis,properties and application to organic electronics

This review is devoted to low and high molecular mass electroactive materials containing triphenylamine (TPA) structural units. It is shown that by appropriate selection of C–C coupling methods, it is possible to obtain solution-processable, electroactive materials of tunable donor–acceptor properties, suitable for the use as active layers in p-channel or ambipolar field effect transistors, as hole-transporting layers and as electroluminophores in organic light-emitting diodes. Other applications involve their use as components of bulk heterojunctions in organic solar cells and dye-sensitized solar cells. Since TPA-based materials exhibit high electrochemical reversibility, they can also be technologically exploited as solution-processable electrochromic materials.     

Metal complexes in molecular electronics: progress and possibilities

A selective summary of some of the issues surrounding the development of a molecular-based electronics technology is presented, highlighting the characteristics of metal complexes that make these species particularly attractive for the construction of highly integrated, functional molecular components.     

Digital pulse processing: New possibilities in portable electronics

In this paper we discuss the advantages that digital processors have, compared to traditional analog spectrometers, and present some of the opportunities these offer for next generation portable instruments. We begin with a comparison of the topologies of analog and digital instruments and then show how digital processors' ability to operate on pulse specific information is applied to two example cases: ballistic deficit correction in large Ge detectors and particle identification in CsI(Tl) scintillators. Finally, we examine the power budget of existing XIA instruments and show an easy path to lower power portable devices in the future.     

Entropy production in living systems: from organisms to ecosystems

Entropy production in the human body as a whole can be calculated from observed energetic data. The entropy production in humans thus calculated shows a two-stage character over the human life span, that is an early increasing stage and a later decreasing stage until death. Similar methods for calculating entropy production are also applied to lake ecosystems. Entropy production in two lakes (Lake Biwa in Japan and Lake Mendota in USA) has been calculated, and it is found that entropy production per year per volume of lake water in the eutrophic Lake Mendota is larger than that in the oligotrophic Lake Biwa. Because ecological succession (evolution) in a lake always proceeds from oligotrophy to eutrophy, the present results suggest that processes of ecological succession accompany the increase in entropy production. This situation is parallel to the trend in the early stage of the human life span. Based on the above discussion, a hypothesis is presented on the entropy principle in living systems.     

Filler-nanocellulose substrate for printed electronics: experiments and model approach to structure and conductivity

Composites made of inorganic filler particles and cellulose nanofibres can be applied as substrates for printed electronics. We have studied the structural properties of these substrates both experimentally and with particle-level modeling approach. Our model describes the skeleton structure formed by pigment particles of varied shapes and size distributions. Nanocellulose is assumed to fill voids of the structure. The model simulations predict quite well the relative changes in measured density, porosity and roughness for kaolin and precipitated calcium carbonate (PCC) pigments. Measured roughness turns out to be higher for kaolin than for PCC. Yet, the measured conductivity of printed lines on kaolin surface is higher than the conductivity on the PCC surface. The simulations reveal a more open surface pore structure for PCC than for kaolin, which leads to stronger absorption of the silver ink, and thus explains the differences in the measured conductivities.