Combinatorial selectivity with an array of phthalocyanines functionalized TiO2/ZnO heterojunction thin film sensors

The development of electronic noses requires the control of the selectivity pattern of each sensor of the array. Organic chemistry offers a manifold of possibilities to this regard but in many cases the chemical sensitivity is not matched with the response of electronic sensor. The combination of organic and inorganic materials is an approach to transfer the chemical sensitivities of the sensor to the measurable electronic signals. In this paper, this approach is demonstrated with a hybrid material made of phthalocyanines and a bilayer structure of ZnO and TiO2. Results show that the whole spectrum of sensitivity of phthalocyanines results in changes of the resistance of the sensor, and even the adsorption of compounds, such as hexane, which cannot change the resistance of pure phthalocyanine layers, elicits changes of the sensor resistance. Furthermore, since phthalocyanines are optically active, the sensitivity in dark and visible light are different. Thus, operating the sensor in dark and light two different signals per sensors can be extracted. As a consequence, an array of 3 sensors made of different phthalocyanines results in a virtual array of six sensors. The sensor array shows a remarkable selectivity respect to a set of test compounds. Principal component analysis scores plot illustrates that hydrogen bond basicity and dispersion interaction are the dominant mechanisms of interaction.

Developing Predictive Models for Carrying Ability of Micro-Plastics towards Organic Pollutants

Microplastics, which have been frequently detected worldwide, are strong adsorbents for organic pollutants and may alter their environmental behavior and toxicity in the environment. To completely state the risk of microplastics and their coexisting organics, the adsorption behavior of microplastics is a critical issue that needs to be clarified. Thus, the microplastic/water partition coefficient (log Kd) of organics was investigated by in silico method here. Five log Kd predictive models were developed for the partition of organics in polyethylene/seawater, polyethylene/freshwater, polyethylene/pure water, polypropylene/seawater, and polystyrene/seawater. The statistical results indicate that the established models have good robustness and predictive ability. Analyzing the descriptors selected by different models finds that hydrophobic interaction is the main adsorption mechanism, and π−π interaction also plays a crucial role for the microplastics containing benzene rings. Hydrogen bond basicity and cavity formation energy of compounds can determine their partition tendency. The distinct crystallinity and aromaticity make different microplastics exhibit disparate adsorption carrying ability. Environmental medium with high salinity can enhance the adsorption of organics and microplastics by increasing their induced dipole effect. The models developed in this study can not only be used to estimate the log Kd values, but also provide some necessary mechanism information for the further risk studies of microplastics.

Solubility of Cellulose in Binary Mixtures of 1-Alkyl-3-methylimidazolium Acetate and Dimethyl Sulfoxide: Influence of Alkyl Chain Length in the Cation

The influence of alkyl chain length of cations on cellulose solubility in a neat imidazolium (MIM)-based ionic liquid (IL) [CnMIM][OAc] and [CnMIM][OAc]–DMSO binary system (n=0–6) was investigated. The correlation between cellulose solubility and Kamlet–Taft hydrogen bond basicity (β) was also examined. Cellulose solubility (g per mol IL) in neat [CnMIM][OAc] increased as the cation alkyl chain length decreased from 6 to 2. However, alkyl chain lengths of 1 and 0 resulted in extremely poor cellulose solubility, indicating that a chain length of 2 was optimal for dissolution of cellulose in the system. Cellulose solubility in the [CnMIM][OAc]–DMSO binary system (n=1–6) was greater than that in neat IL, with maximum solubility occurring at an IL mole fraction of ~0.2. Maximum cellulose solubility in the [CnMIM][OAc]–DMSO binary system was slightly better at even alkyl chain lengths (n=2, 4, or 6) than at odd chain lengths (n=1, 3, or 5), with the best solubility at n=4. More interestingly, maximum cellulose solubility and specific IL mole fraction in the IL-DMSO binary system were related with the β values of neat ILs, even with ILs containing different anionic species or cation alkyl chain lengths. This indicates that solubility information in IL-DMSO binary systems is influenced by the characteristics of neat ILs.

Hydrogen bond basicity of ionic liquids and molar entropy of hydration of salts as major descriptors in the formation of aqueous biphasic systems

A predictive model for ionic liquid/salt aqueous biphasic systems’ formation based on the hydrogen bond basicity of ionic liquids and molar entropy of hydration of salts.

A closer look into deep eutectic solvents: exploring intermolecular interactions using solvatochromic probes

Kamlet Taft solvatochromic parameters, namely the hydrogen-bond acidity, hydrogen-bond basicity and dipolarity/polarizability and ETN parameters of a wide range of DESs composed of cholinium chloride, dl-menthol and a quaternary ammonium salt ([N4444]Cl), and corresponding ILs are here presented.