The field of polyoxometalates (POMs), although a mature field, continues to attract significant attention. The number of publications and patents continues to grow. New researchers are entering the field. The scientific communities of fast-growing new economic/technology powers such as Peoples Republic of China and India are becoming important contributors of the total number of worldwide publications on POMs. Figure 1 depicts the growth of the POM literature per year since 1966. In 1996, according to Chemical Abstracts, nearly 600 refereed publications and over 120 patents were issued in reference to the POM chemistry and technology. Figure 2 shows the countries where the most research activity exists based on publications, and Figure 3 lists the 10 largest patent assignee countries in the world. Japan issues 40% of the worldwide patent literature followed by the USA with ∼17%. The applications of POMs are based on combinations of so-called “value-adding properties” which are summarized in Table 1. From the above-listed properties, the applications of POMs are centered primarily on their redox properties, photochemical response, ionic charge, conductivity, and ionic weights. The majority of the patent and applied literature is devoted to the applications of the Keggin type heteropolyacids (HPA) and their salts. Primarily H3PMo12O40, H3PW12O40, H4SiMo12O40, and H4SiW12O40 are used as the main examples for many applications. Their popularity can be attributed to a large extent to the enormous volume of literature over several decades that describes their fundamental chemistry and to their commercial availability, which makes them convenient starting materials. Approximately two-thirds of the applied chemistry/technology literature describes applications that are based on these POMs. Dimitris E. Katsoulis was born in Athens, Greece in 1955. He received a B.S. degree in Chemistry from University of Athens in 1977. He subsequently joined the research group of Prof. Michael T. Pope at Georgetown University and obtained a Ph.D. degree in 1985. He continued with a postdoctoral assignment at Georgetown University, and in 1988 he joined the Science and Technology function of Dow Corporation in Midland Michigan. He is currently an Associate Research Scientist in the Rigid Materials Science Expertise Center (Central R&D) in Dow Corning. His research interests include hybrid materials, with focus on siloxane-polyoxometalate compositions, sol−gel chemistry, silsesquioxanes, gel systems, polymer matrix composites, and nanocomposites. 359 Chem. Rev. 1998, 98, 359−387

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A Survey of Applications of Polyoxometalates

Buffers for pH and Metal Ion Control

The Acanthaceae family is an important source of therapeutic drugs, and the ethnopharmacological knowledge of this family requires urgent documentation as several of its species are near extinction. Justicia is the largest genus of Acanthaceae, with approximately 600 species. The present work provides a review addressing the chemistry and pharmacology of the genus Justicia. In addition, the biological activities of compounds isolated from the genus are also covered. The chemical and pharmacological information in the present work may inspire new biomedical applications for the species of Justicia, considering atom economy, the synthesis of environmentally benign products without producing toxic by-products, the use of renewable sources of raw materials, and the search for processes with maximal efficiency of energy.

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Chemical constituents and biological activities of species of Justicia: a review

Methods of analysis of 4-quinolone antibacterials

The development and applications of ion-selective membrane electrodes continue to provide excitement in expanding areas of analytical chemistry, including analytical pharmaceutical research and analysis, because these sensors offer the advantages of simple design, construction, and manipulation, reasonable selectivity, fast response time, applicability to colored and turbid solutions, and possible interfacing with automated and computerized systems. The combination of membrane sensors with flow injection analysis (FIA) for the determination of various organic ions of biological interest (e.g., drugs) is a new promising area with many applications. This review covers the material that is of interest to those who deal with ion-selective electrodes in organic and pharmaceutical analysis.

Recent Advances in Pharmaceutical Analysis with Potentiometric Membrane Sensors

A metoclopramide (MCP) ion-selective PVC membrane electrode based on the ion-pair complex of MCP with sodium tetraphenylborate was prepared with dioctyl phthalate as a plasticiser. The electrode exhibits a linear response with an approximate Nernstian slope (50 mV decade–1 at 20 °C) within the concentration range 10–1.7–10–5.6M MCP. The effects of ionic strength and pH of the test solution on the electrode performance were studied. The electrode exhibited very good selectivity for MCP with respect to a large number of inorganic and organic cations of biological importance. The standard additions method and potentiometric titration were used to determine the MCP in pure solutions and in pharmaceutical preparations with satisfactory results.

Ion-selective electrode for the determination of metoclopramide

New plastic membrane electrodes for pipazethate hydrochloride 
based on pipazethatium phosphotungstate, pipazethatium phosphomolybdate and 
a mixture of the two were prepared. The electrodes were fully characterized 
in terms of composition, life span, pH and temperature and were then 
applied to the potentiometric determination of the pipazethate ion in its 
pure state and pharmaceutical preparations under batch and flow injection 
conditions. The selectivity of the electrodes towards many inorganic 
cations, sugars and amino acids was also tested.

A. F. Shoukry

Papers

Ion-selective electrode for the determination of metoclopramide

Flow injection potentiometric determination of pipazethate hydrochloride

Conductimetric determination of reproterol HCl and pipazethate HCl and salbutamol sulphate in their pharmaceutical formulations

Flow injection potentiometric determination of amantadine HCl.

Determination of tetracycline and related compounds using plastic membrane ion-selective electrodes