Search Results for « Chemistry »

The introduction of the dimension of green chemistry into the assessment of analytical methods should be a natural development trend in chemistry and should coincide with its general policy. Some of the principles of green chemistry - such as prevention of waste generation; safer solvents and auxiliaries; design for energy efficiency; safer chemistry to minimize the potential of chemical accidents; development of instrumental methods - are directly related to analytical chemistry. Analytical chemistry is considered to be a small-scale activity, but this is not always true in the case of controlling and monitoring laboratories whose number of runs performed is high. This makes an analytical laboratory comparable with the fine chemicals or pharmaceutical industry. The use of instrumental methods instead of wet chemistry, automation, and minimization is a new trend in analytical chemistry, making this branch of chemistry more sustainable. In this study, widespread separation methods are considered and an attempt is made to characterize them against the above-mentioned principles. Special attention is given to capillary electrophoresis (CE), which provides a very good opportunity to improve analytical chemistry by replacing many chromatographic methods that consume large volumes of solvents. The choice of different solvents and micronization in analytical chemistry is also discussed.

The field of atmospheric chemistry is very broad, both in the problems addressed and in the approaches taken. Thus, it includes laboratory and theoretical studies, field measurements, and modeling, and addresses chemistry from the lower to the upper atmosphere, in remote and polluted regions, from marine to continental areas, and both outdoors and indoors. Given this complexity, it is impossible to capture all aspects with the limited number of articles that can be included in a special feature. Thus, what follows should be taken as illustrative rather than inclusive. The genesis of the field of atmospheric chemistry lies in air pollution in the troposphere (lower atmosphere), for which there is documentation at least as long ago as the 13th century. Dramatic incidents of excess deaths such as in the Meuse Valley, Belgium, in 1930 (1), and in London, England, in 1952 (2) brought public and scientific attention to “smog” (smog = smoke + fog) and, in particular, to the problem of sulfur dioxide and sulfate particles it forms in air, as well as to direct emissions of particles from combustion sources. Around 1950, what initially appeared to be a different kind of smog, now known as photochemical air pollution, was recognized in the Los Angeles area. The seminal work of Haagen-Smit demonstrated that the necessary ingredients (primary pollutants) were volatile organic compounds (VOC), oxides of nitrogen (NOx = NO + NO2), and sunlight. The wavelengths available to drive photochemistry at the earth's surface are restricted to … 1E-mail: bjfinlay{at}uci.edu.

Building on our ability to design and synthesise molecules and our understanding of the noncovalent interactions between these molecules, the chemical sciences are currently entering the new territory of Systems Chemistry. This young field aims to develop complex molecular systems showing emergent properties; i.e. properties that go beyond the sum of the characteristics of the individual consituents of the system. This review gives an impression of the state of the art of the field by showing a diverse number of recent highlights, including out-of-equilibrium self-assembly, chemically fuelled molecular motion, compartmentalised chemical networks and designed oscillators. Subsequently a number of current challenges related to the design of complex chemical systems are discussed, including those of creating concurrent formation-destruction systems, continuously maintaining chemical systems away from equilibrium, incorporating feedback loops and pushing replication chemistry away from equilibrium. Finally, the prospects for Systems Chemistry are discussed including the tantalizing vision of the de novo synthesis of life and the idea of self-synthesising and self-repairing chemical factories.

"Complexity" is a subject that is beginning to be important in chemistry. Historically, chemistry has emphasized the approximation of complex nonlinear processes by simpler linear ones. Complexity is becoming a profitable approach to a wide range of problems, especially the understanding of life.

Machine learning plays an increasingly important role in many areas of chemistry and materials science, being used to predict materials properties, accelerate simulations, design new structures, and predict synthesis routes of new materials. Graph neural networks (GNNs) are one of the fastest growing classes of machine learning models. They are of particular relevance for chemistry and materials science, as they directly work on a graph or structural representation of molecules and materials and therefore have full access to all relevant information required to characterize materials. In this Review, we provide an overview of the basic principles of GNNs, widely used datasets, and state-of-the-art architectures, followed by a discussion of a wide range of recent applications of GNNs in chemistry and materials science, and concluding with a road-map for the further development and application of GNNs.

The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-established and recently developed green analytical chemistry metrics, including NEMI labeling and analytical Eco-scale, are presented. Additionally, this paper focuses on the possibility of the use of multivariate statistics in evaluation of environmental impact of analytical procedures. All the above metrics are compared and discussed in terms of their advantages and disadvantages. The current needs and future perspectives in green chemistry metrics are also discussed.