Morphological and palaeoecological aspects of fossil insects unveiled by UV-A light.

Studying insect fossils, particularly those preserved as compressions in sedimentary matrices, can be difficult due to the taphonomic processes that often result to poor preservation and contrast of structures compared to the embedding matrix. To address this, we propose a user-friendly and simple methodology based on UV-light to study insect fossils and select specimens of interest for more advanced imagery exploration. While UV-light imaging has been previously applied to compressions of arthropod fossils, it typically involved laser light sources.

Halogen bonding effect on electrochemical anion oxidation in ionic liquids.

Three Ionic liquids (ILs) based on an imidazolium core have been compared and used as solvents for the oxidation of various anions. Electrochemical experiments as well as NMR titrations and X-ray diffraction analyses unambiguously confirm the crucial role of non-covalent halogen bonding on the oxidation potentials and consequently the electrochemical window of the respective ILs.

Bright green fluorescence of Asian paper wasp nests.

An exceptionally bright fluorescent biomatter was discovered when exploring, with UV-A light, the nests of several oriental paper wasp species of the genus , a genus of diurnal social insects. Fluorescence spectra of the cocoon cap membranes revealed narrow emission bands in the green range of the visible spectrum. Large Stokes shifts of around 160 nm and high fluorescence quantum yields of up to 35% were measured.

Electrochemically driven interfacial halogen bonding on self-assembled monolayers for anion detection.

Electrochemically driven interfacial halogen bonding between redox-active SAMs and halide anions was quantitatively studied for the first time. The halogen bond donor properties were switched on by electrochemically controlling the oxidation state of the adsorbates. Experimental data and simulation show high binding enhancement towards halide anions compared to homogeneous systems.

Comparative study of non-covalent interactions between cationic N-phenylviologens and halides by electrochemistry and NMR: the halogen bonding effect.

Five N-phenylviologen (PV) derivatives have been synthesized and their electrochemical behavior in the presence of halide anions has been studied. Further investigations were carried out by H and F NMR spectroscopy at different chloride concentrations. This is the first time a systematic study combines cyclic voltammetry and NMR spectroscopy in order to analyse the contribution of halogen bonding among the various non-covalent interactions between iodinated N-phenylviologens.

Self-assembled monolayer formation of a (N)Fe(ii) complex on gold electrodes: electrochemical properties and coordination chemistry on a surface.

A coordinatively unsaturated Fe complex bearing a pentadentate ligand (N,N',N'-tris(2-pyridyl-methyl)-1,2-diaminoethane) functionalized with a cyclic disulfide group has been prepared in order to graft reactive metal entities as self-assembled monolayers (SAMs) on gold electrodes. Prior to grafting, exogenous ligand exchange has been investigated by cyclic voltammetry (CV) in solution, showing that the nature of the first coordination sphere (N)Fe-X (X = Cl, OTf, MeCN, acetone) can be tuned, thanks to the control of the chemical conditions. The Fe complex has been immobilized on gold electrodes by spontaneous (passive) adsorption as well as by an electro-assisted method.

Electrochemical controlling and monitoring of halogen bond formation in solution.

Cyclic voltammetry has been used for the first time to probe and to control the formation of non-covalent halogen bonding (XB) via redox switching. These results strongly encourage the use of electrochemistry as an economical and precisely controllable tool for the investigation of XB in solution.

Rational design of a redox-labeled chiral target for an enantioselective aptamer-based electrochemical binding assay.

A series of redox-labeled L-tyrosinamide (L-Tym) derivatives was prepared and the nature of the functional group and the chain length of the spacer were systematically varied in a step-by-step affinity optimization process of the tracer for the L-Tym aptamer. The choice of the labeling position on L-Tym proved to be crucial for the molecular recognition event, which could be monitored by cyclic voltammetry and is based on the different diffusion rates of free and bound targets in solution. From this screening approach an efficient electroactive tracer emerged.

Switching on/off the chemisorption of thioctic-based self-assembled monolayers on gold by applying a moderate cathodic/anodic potential.

An in situ and real-time electrochemical method has been devised for quantitatively monitoring the self-assembly of a ferrocene-labeled cyclic disulfide derivative (i.e., a thioctic acid derivative) on a polycrystalline gold electrode under electrode polarization.

Synthesis and characterization of oligonucleotide conjugates bearing electroactive labels.

Oxime bond formation has been applied to the preparation of oligonucleotides labeled with electrochemical ferrocene and viologen labels. Aminooxy functionalized ferrocene and viologen derivatives were prepared by a straightforward route and efficiently conjugated with aldehyde containing oligonucleotides either at 3' or 5' end. Both labels were found to not disturb the recognition properties of the oligonucleotide.

Water-soluble, redox-active organometallic calcium chelators.

This paper describes a new series of organometallic water-soluble chelators combining a redox moiety (ferrocene) and a selective Ca2+ chelator (BAPTA) separated by an ethynyl bridge. We report the synthesis and characterization of organometallic derivatives of the BAPTA chelator featuring one (2a) and two ferrocenyl (2b) moieties. Single crystal X-ray structural analysis on these chelators revealed unexpected conformations for the ferrocenyl substituent with respect to the phenyl ring of the BAPTA unit.

Simple and highly enantioselective electrochemical aptamer-based binding assay for trace detection of chiral compounds.

A new electrochemical methodology is reported for monitoring in homogeneous solution the enantiospecific binding of a small chiral analyte to an aptamer. The principle relies on the difference of diffusion rates between the targeted molecule and the aptamer/target complex, and thus on the ability to more easily electrochemically detect the former over the latter in a homogeneous solution. This electrochemical detection strategy is significant because, in contrast to the common laborious and time-consuming heterogeneous binding approaches, it is based on a simple and fast homogeneous binding assay which does not call for an aptamer conformational change upon ligand binding.

Do molecular conductances correlate with electrochemical rate constants? Experimental insights.

We measured single-molecule conductances for three different redox systems self-assembled onto gold by the STMBJ method and compared them with electrochemical heterogeneous rate constants determined by ultrafast voltammetry. It was observed that fast systems indeed give higher conductance. Monotonous dependency of conductance on potential reveals that large molecular fluctuations prevent the molecular redox levels to lie in between the Fermi levels of the electrodes in the nanogap configuration.

An organometallic derivative of a BAPTA ligand: towards electrochemically controlled cation release in biocompatible media.

The combination of a ferrocenyl moiety with BAPTA provides a novel, water-soluble, redox-active chelator. This chelator behaving as a conformational sensor exhibits an unexpected electrochemical response with high affinity and selectivity for calcium.

Electrochemically assisted fabrication of metal atomic wires and molecular junctions by MCBJ and STM-BJ methods.

Atomic wires (point contacts) and molecular junctions are two fundamental units in the fields of nanoelectronics and devices. This Minireview introduces our recent approaches aiming to develop versatile methods to fabricate and characterize these unique metallic and molecular structures reliably. Electrochemical methods are coupled with mechanically controllable break junction (EC-MCBJ) or scanning tunneling microscopy (STM) break junction (EC-STMBJ) methods to fabricate metallic point contacts and metal/molecule/metal junctions.

Electroactive benzothiazole hydrazones and their [Mo6O19]2- derivatives: promising building blocks for conducting molecular materials.

The electroactive benzothiazole hydrazone AMBTH-H(2), a new member of the 2,2'-azino-bis(N-alkylbenzothiazole) family, was synthesised in a five-step procedure and characterised by using X-ray diffraction along with two intermediates and the N-methylbenzothiazole hydrazone MBTH-H(2). Both AMBTH-H(2) and MBTH-H(2) were coupled to [Mo(6)O(19)](2-) in acetonitrile in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine to give two new diazoalkane-hexamolybdates, which were isolated as tetrabutylammonium salts and characterised by using IR, UV/Vis and NMR spectroscopies, cyclic voltammetry and, for one of them, X-ray diffraction. The packing arrangement molecules in crystals of AMBTH-H(2), the redox features of the AMBTH-hexamolybdate hybrid together with a good electronic communication between the organic pi system and the molybdenum centres make these compounds very promising blocks for the synthesis of conducting molecular materials.

The fabrication and characterization of adjustable nanogaps between gold electrodes on chip for electrical measurement of single molecules.

This work reports on a new method to fabricate mechanically controllable break junctions (MCBJ) with finely adjustable nanogaps between two gold electrodes on solid state chips for characterizing electron transport properties of single molecules. The simple, low cost, robust and reproducible fabrication method combines conventional photolithography, chemical etching and electrodeposition to produce suspended electrodes separated with nanogaps. The MCBJ devices fabricated by the method can undergo many cycles in which the nanogap width can be precisely and repeatedly varied from zero to several nanometers.

Revealing molecular self-assembly and geometry of non-covalent halogen bonding by solid-state NMR spectroscopy.

We report a new spectroscopic fingerprint of intermolecular contacts in halogen bond-driven self-assembling aggregates and a precise determination of intermolecular NI distances in microcrystalline samples.

Theory and practice of enzyme bioaffinity electrodes. Direct electrochemical product detection.

The use of enzyme labeling techniques to convert biorecognition events into high sensitivity electrochemical signals may follow two different strategies. One, in which the current is the electrocatalytic response of a redox couple serving as cosubstrate to a redox enzyme label and another that consists in the detection of an electrochemically active product of the enzyme label. The theoretical relationships that link, in the latter case, the electrochemical current response to the amount of recognized labeled target analyte are established for steady-state diffusion-convection chronoamperometric regimes.

Ultrafast voltammetry for probing interfacial electron transfer in molecular wires.

Electron transfer inside self-assembled monolayers made from complex redox-active oligophenylenevinylene molecular wires is examined by ultrafast cyclic voltammetry. Rate constants above 10(6) s(-1) are measured when the electroactive moieties are easily accessible to counterions from the electrolyte. These counterion movements are necessary to compensate the local charge created upon electron transfer.

Dense monolayers of metal-chelating ligands covalently attached to carbon electrodes electrochemically and their useful application in affinity binding of histidine-tagged proteins.

In this work, monolayers of metal complexes were covalently attached to the surface of carbon electrodes with the goal of binding monolayers of histidine-tagged proteins with a controlled molecular orientation and a maintained biological activity. In this novel method, which is simple, versatile, and efficient, the covalent attachment was accomplished in a single step by the electrochemical reduction of aryl diazonium ions that were substituted with a nitrilotriacetic (NTA) or an imminodiacetic (IDA) ligand at the para position. The transient aryl radicals that were generated in the reduction were grafted to the surfaces of glassy carbon, highly oriented pyrolitic graphite, and graphite-based screen-printed electrodes, producing dense monolayers of the ligands.