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.

Electrocatalytic miRNA detection using cobalt porphyrin-modified reduced graphene oxide.

Metalated porphyrins have been described to bind nucleic acids. Additionally, cobalt porphyrins present catalytic properties towards oxygen reduction. In this work, a carboxylic acid-functionalized cobalt porphyrin was physisorbed on reduced graphene oxide, then immobilized on glassy carbon electrodes. The carboxylic groups were used to covalently graft amino-terminated oligonucleotide probes which are complementary to a short microRNA target. It was shown that the catalytic oxygen electroreduction on cobalt porphyrin increases upon hybridization of miRNA strand ("signal-on" response). Current changes are amplified compared to non-catalytic amperometric system. Apart from oxygen, no added reagent is necessary. A limit of detection in the sub-nanomolar range was reached. This approach has never been described in the literature.

A chiral rhenium complex with predicted high parity violation effects: synthesis, stereochemical characterization by VCD spectroscopy and quantum chemical calculations.

With their rich electronic, vibrational, rotational and hyperfine structure, molecular systems have the potential to play a decisive role in precision tests of fundamental physics. For example, electroweak nuclear interactions should cause small energy differences between the two enantiomers of chiral molecules, a signature of parity symmetry breaking. Enantioenriched oxorhenium(VII) complexes S-(-)- and R-(+)-3 bearing a chiral 2-methyl-1-thio-propanol ligand have been prepared as potential candidates for probing molecular parity violation effects via high resolution laser spectroscopy of the Re=O stretching. Although the rhenium atom is not a stereogenic centre in itself, experimental vibrational circular dichroism (VCD) spectra revealed a surrounding chiral environment, evidenced by the Re=O bond stretching mode signal. The calculated VCD spectrum of the R enantiomer confirmed the position of the sulfur atom cis to the methyl, as observed in the solid-state X-ray crystallographic structure, and showed the presence of two conformers of comparable stability. Relativistic quantum chemistry calculations indicate that the vibrational shift between enantiomers due to parity violation is above the target sensitivity of an ultra-high resolution infrared spectroscopy experiment under active preparation.

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.

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.

Engineering tuneable light-harvesting systems with oligothiophene donors and mono- or bis-bodipy acceptors.

Oligothiophene-Bodipy-based donor-acceptor systems for light harvesting have been synthesized and characterized. Absorption, excitation, and emission spectra indicate a tuneable and efficient resonance energy transfer from quaterthiophene as donor to mono- and bis-Bodipy as acceptors. This shows that engineering tuneable light harvesting systems is possible based on the combination of oligothiophenes with one or two Bodipy(s).

Lambda-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.