Challenges, Prospects, and Emerging Applications of Inkjet-Printed Electronics: A Chemist's Point of View

Driven by the development of new functional inks, inkjet-printed electronics has achieved several milestones upon moving from the integration of simple electronic elements (e.g., temperature and pressure sensors, RFID antennas, etc.) to high-tech applications (e.g. in optoelectronics, energy storage and harvesting, medical diagnosis). Currently, inkjet printing techniques are limited by spatial resolution higher than several micrometers, which sets a redhibitorythreshold for miniaturization and for many applications that require the controlled organization of constituents at the nanometer scale. In this Review, we present the physico-chemical concepts and the equipment constraints underpinning the resolution limit of inkjet printing and describe the contributions from molecular, supramolecular, and nanomaterials-based approaches for their circumvention. Based on these considerations, we propose future trajectories for improving inkjet-printing resolution that will be driven and supported by breakthroughs coming from chemistry. Please check all text carefully as extensive language polishing was necessary. Title ok? Yes.

Self-Assembly of Nanoparticles from Evaporating Sessile Droplets: Fresh Look into the Role of Particle/Substrate Interaction

We studied the dependence of solid deposit shape obtained by free drying of sessile drops on particle concentration and Derjaguin-Landau-Verwey-Overbeek (DLVO) particle/substrate interaction. In contrast to previous contributions using pH as a control parameter of interactions, we investigated an unprecedentedly wide range of concentrations and particle/substrate DLVO forces by modifying the nature of the substrate and particles as well as their size and surface chemistry, whereas long-distance repulsive interactions between particles were maintained for most of the drying time. Our main result is that the different shapes of deposits obtained by modifying the particle concentration are the same in the different regimes of concentration regardless of particle/substrate interaction in the studied range of DLVO forces and particle concentrations. The second result is that, contrary to expectations, the dominant morphology of dry patterns at low particle concentration always shows a dotlike pattern for all the studied systems.

Morphological Control of Linear Particle Deposits from the Drying of Inkjet-Printed Rivulets

We studied the morphology of linear particle deposits obtained by inkjet printing of a silica nanoparticle suspension in drying conditions where contact line depinning occurs. We show that this evaporation mode can be obtained by adjusting the particle concentration in different solvents. For isolated drops, deposited manually or by inkjet printing, drying induces the formation of two concentric rings in which particles self-assemble into a monolayer. For fused drops, our main result is that stable rivulets could be formed by drop overlap leading, after drying, to the formation of three parallel lines composed of a self-assembled particle monolayer. The three lines are of homogeneous thickness with two very thin outer lines (∼1 μm width) and a wider central line (∼20 μm width). We reveal how the width of the resulting lines is influenced by drop spacing in a predictable manner for a large experimental window knowing the drop size.

Monitoring photosynthetic microorganism activity with an electrolyte-gated organic field effect transistor

Among organic thin film transistors (OTFTs), Organic Electrochemical Transistors (OECTs) have been extensively used for cell monitoring while Electrolyte-Gated Organic Field-Effect Transistors (EGOFETs) have never been described for that kind of application. However, EGOFETs are well adapted for this use because, as well as OECTs, they can operate directly in aqueous solutions such as cells culture media, but they offer much a higher on/off ratio which could lead to better sensitivity. As a proof of concept, we propose herein to monitor the photosynthetic activity of a cyanobacterium (Anabaena flos-aquae) contained within an EGOFET's electrolyte.

A frugal implementation of Surface Enhanced Raman Scattering for sensing Zn2+ in freshwaters - In depth investigation of the analytical performances

Surface Enhanced Raman Scattering (SERS) has been widely praised for its extreme sensitivity but has not so far been put to use in routine analytical applications, with the accessible scale of measurements a limiting factor. We report here on a frugal implementation of SERS dedicated to the quantitative detection of Zn²⁺ in water, Zn being an element that can serve as an indicator of contamination by heavy metals in aquatic bodies. The method consists in randomly aggregating simple silver colloids in the analyte solution in the presence of a complexometric indicator of Zn²⁺, recording the SERS spectrum with a portable Raman spectrometer and analysing the data using multivariate calibration models. The frugality of the sensing procedure enables us to acquire a dataset much larger than conventionally done in the field of SERS, which in turn allows for an in-depth statistical analysis of the analytical performances that matter to end-users. In pure water, the proposed sensor is sensitive and accurate in the 160-2230 nM range, with a trueness of 96% and a precision of 4%. Although its limit of detection is one order of magnitude higher than those of golden standard techniques for quantifying metals, its sensitivity range matches Zn levels that are relevant to the health of aquatic bodies. Moreover, its frugality positions it as an interesting alternative to monitor water quality. Critically, the combination of the simple procedure for sample preparation, abundant SERS material and affordable portable instrument paves the way for a realistic deployment to the water site, with each Zn reading three to five times cheaper than through conventional techniques. It could therefore complement current monitoring methods in a bid to solve the pressing needs for large scale water quality data.

In-solution patterning of standing up porphyrin based nanostructures within hydrogen bonded porous networks--a structural effect of a host matrix on guest entities

Through an all-solution process, we elaborate a host-guest system based on the self-assembly of a porphyrin derivative entrapped in a PTCDI-melamine porous network on Au(111). In contrast to the unpatterned molecular assembly, complementary STM and surface IR spectroscopy show that the host template modifies the packing and the tilt angle of porphyrin nanodomains.

Long-range ordered nanodomains of grafted electroactive molecules

We demonstrate the capability to build zero and one-dimensional electroactive molecular nanostructures ordered over a macroscopic scale and stable under ambient conditions. To realize these arrays, we use the selective grafting of functionalized thiols (juglon and terthiophene based) on a self-organized metallic template. The nanoscale patterning of the molecular conductance is demonstrated and analyzed by scanning tunneling spectroscopy. Finally, the influence of the nanostructuring on electro-chemical properties is measured, paving the way to an all-bottom-up fabrication of nanostructured templates for nanosciences.

Multifunctional and reactive enantiopure organometallic helicenes: tuning chiroptical properties by structural variations of mono- and bis(platinahelicene)s

Acetylacetonato-platina[6]- and -platina[7]helicenes have been prepared from 2-pyridyl-substituted benzophenanthrene ligands by following a two-step cycloplatination reaction. The photophysical properties (UV-visible absorption and emission behavior) and chiroptical properties (circular dichroism and molar rotation) of the resolved enantiomers have been measured. These metallahelicenes constitute a novel family of easily accessible helicene derivatives that exhibit large and tuneable chiroptical properties that can be rationalized theoretically and compared to the parent [6]- and [7]carbohelicenes. Furthermore, they are red phosphors at room temperature and their large chiroptical properties can be modulated by oxidation of the metal center to Pt(IV). Hetero- and homochiral diastereomeric bis(metallahelicene)s that possess a rare Pt(III)-Pt(III) scaffold bridged by benzoato ligands have also been prepared. It is shown that the heterochiral (P,M)-bis(Pt(III)-[6]helicene) 9a(1) can isomerize into the homochiral (P,P)- and (M,M)-bis(Pt(III)-[6]helicene) 9a(2). Spectral assignments and an analysis of the optical rotation of these systems were made with the help of time-dependent density functional theory. The calculations highlight the contributions of the metal centers to the chiroptical properties. For 9a(1) and 9a(2), σ-π conjugation between the helicenes and the Pt-Pt moiety may contribute strongly to the optical rotation and electronic circular dichroism.

Progress toward the first observation of parity violation in chiral molecules by high-resolution laser spectroscopy

Parity violation (PV) effects in chiral molecules have so far never been experimentally observed. To take up this challenge, a consortium of physicists, chemists, theoreticians, and spectroscopists has been established and aims at measuring PV energy differences between two enantiomers by using high-resolution laser spectroscopy. In this article, we present our common strategy to reach this goal, the progress accomplished in the diverse areas, and point out directions for future PV observations. The work of André Collet on bromochlorofluoromethane (1) enantiomers, their synthesis, and their chiral recognition by cryptophanes made feasible the first generation of experiments presented in this article.

Λ-Type Regioregular Oligothiophenes: Synthesis and Second-Order NLO Properties

The synthesis of a new series of Lambda-type, D-Pi-A regioregular oligothiophenes is described. The simultaneous presence of the chiral centers and the Lambda-type structure disfavored the formation of centro-symmetrical dimeric assemblies. Hence, enhanced first hyperpolarizabilities betaHRS were measured in comparison with those of the corresponding monomers.

Enantioselective epoxidation of olefins with chiral metalloporphyrin catalysts

The intent of this tutorial review is to cover the recent progress accomplished in iron and manganese porphyrin-catalyzed enantioselective epoxidation of terminal olefins. The literature is covered up to the beginning of 2005. In the first part of the manuscript, we will present the results obtained with simple catalysts in the early eighties, before describing the pickets and strapped series reported more recently. We will also place a special emphasis on the biomimetic approach that oriented most of this research throughout the years. As a conclusion, we will demonstrate that easy-to-prepare porphyrin catalysts should play an important role in the future and should compete with other well-known, successful systems. Among those, the popular titanium tartrate-catalyzed Sharpless-Katsuki asymmetric epoxidation allows the conversion of allylic alcohols to chiral epoxides with high enantiomeric excesses and high conversion. We will also cite the chiral metallosalen complexes independently reported by Jacobsen and Katsuki in 1990. Using manganese-salens, cis-1,2-disubstituted, trisubstituted and some tetrasubstituted olefins are efficiently epoxidized with high enantiomeric excess. However, they suffer from two major drawbacks. They often require low temperature for the epoxidation of monosubstituted (57% ee for styrene at 5 degrees C; 80% at -78 degrees C). More importantly, they proceed with low turnover numbers, TON (TON approximately 40 for styrene). More recently, a new approach involving metal-free chiral dioxiranes was also reported. In some cases, they constitute an interesting alternative to the more common systems previously discussed. Compared to the three pre-cited systems, chiral metalloporphyrins allow the enantioselective epoxidation of unfunctionalized terminal olefins with high enantiomeric excess (>97% ee for styrene) and impressive turnover numbers (>16000) when PhIO is used as oxidant. These results highlight the remarkable potential of porphyrin-based catalysts.