A Solid-State pH Sensor for Nonaqueous Media Including Ionic Liquids

A Facile One-Pot Synthesis of Hierarchically Organized Carbon/TiO2 Monoliths with Ordered Mesopores

Sol-gel processing combined with soft templating and gelation-induced phase separation is very sensitive to the precursor sol composition. In this work we present a straightforward synthesis towards hierarchically structured, macroporous carbon/titania monoliths with ordered mesopores derived from resorcinol/formaldehyde monoliths and a glycolated titanium precursor. We demonstrate the influence of various reaction solvents, where diol-based media and the proportion of the catalyst seem to be essential in controlling spinodal decomposition, obtaining similar monolithic structures under different synthesis conditions. Based on these observations, we further homogeneously incorporated TiO₂ into the carbon structure by an in situ synthesis approach, obtaining structural features similar to pure carbon materials with surface areas of about 400 m²  g^-1 , periodically arranged mesopores with a mean distance of 10-11 nm and cellular macroporosity.

High throughput approach to investigating ternary solvents of aqueous non-stoichiometric protic ionic liquids

The use of ionic liquids (ILs) is limited for many applications due to their cost and/or viscosity. An efficient solution is to make mixtures of ILs with molecular solvents. However, it is well known that there are a large number of possible cation and anion combinations resulting in ILs, and this becomes a vast number when these are then combined with a molecular solvent. Therefore, we need structure-property relationships to design new IL-molecular solvent systems. In this work we have applied high throughput methods to investigate IL containing solutions to provide systematic data of a broad compositional space. We have principally focused on the surface tension, apparent pH and liquid nanostructure to identify potential self-assembly and protein stabilizing ability of solvent systems. Non-stoichiometric and aqueous IL-solvents were prepared in a high-throughput manner based on a deliberate experimental design approach such that 26 samples were prepared for each cation-anion-water combination. A selection of 8 protic ionic liquids (PILs) were used as starting materials, comprising ethanol-, ethyl-, butyl-, and pentylammonium cations combined with formate, acetate and nitrate anions. This resulted in a total of 208 different solvent systems. The measured solvent properties showed different trends in base-rich and acid-rich solvent combinations. Surface tensions of base-rich samples exhibited a relatively linear relationship with increasing excess amine, while acid-rich samples were more dominantly affected by the change in water content. Liquid nanostructure of acid-rich samples was retained upon water dilution, whereas a significant SAXS peak shift towards lower scattering angles was observed in the presence of excess amines, indicating larger nanosized aggregates were forming. The design of experiment approach used here is considered to be applicable to any multi-component solvent compositional space due to its suitability in using small data sets to cover large compositional spaces, and hence can be employed to decrease the time and sample quantities required.

Aqueous Brønsted-Lowry Chemistry of Ionic Liquid Ions

Ionic liquids have become commonplace materials found in research laboratories the world over, and are increasingly utilised in studies featuring water as co-solvent. It is reported herein that proton activities, aH (+) , originating from auto-protolysis of H2O molecules, are significantly altered in mixtures with common ionic liquids comprised of Cl(-), [HSO4 ](-), [CH3SO4 ](-), [CH3COO](-), [BF4](-), relative to pure water. paH (+) values, recorded in partially aqueous media as -log(aH (+)), are observed over a wide range (∼0-13) as a result of hydrolysis (or acid dissociation) of liquid salt ions to their associated parent molecules (or conjugate bases). Brønsted-Lowry acid-base character of ionic liquid ions observed is rooted in equilibria known to govern the highly developed aqueous chemistry of classical organic and inorganic salts, as their well-known aqueous pKs dictate. Classical salt behaviour observed for both protic and aprotic ions in the presence of water suggests appropriate attention need be given to relevant chemical systems in order to exploit, or avoid, the nature of the medium formed.

Miniaturisation and simplification of solid-state proton activity sensors for non-aqueous media and ionic liquids

Solid-state proton activity sensors capable of measuring the proton activity of non-aqueous media and ionic liquids regardless of their hydrophobicity and water content were miniaturised and simplified.

Colorimetric and ratiometric pH responses by the protonation of phenolate within hemicyanine

The indolium–phenol based tetramethylene hemicyanine has colorimetric and ratiometric optical responses under acidic and basic conditions.

Brønsted acids in ionic liquids: how acidity depends on the liquid structure

Gutmann Acceptor Number (AN) values have been determined for Brønsted acid–ionic liquid mixtures, over a wide compositional range.

Electrochemical Reactivity on Conducting Polymer Alloys

Embedding macromolecules and active centers such as inorganic nanoparticles into conducting polymers (CPs) has been an ongoing challenge due to the normally harsh conditions required during chemical or electrochemical polymerization that limits the selection of the functional molecules to be incorporated. By developing alternative approaches for incorporating various organic and inorganic materials into CPs it has been possible to obtain efficient charge transfer within the alloys. In this report, two facile techniques are discussed for obtaining such composites: 1) In-situ polymerisation of poly (3,4-ethylenedioxythiophene) (PEDOT) in the presence of non-conducting polymers and 2) electrochemical deposition in-organic nanoparticles inside PEDOT.