Volume 79, Issue 1

For IUPAC, the global, scientific organization that cares about chemistry and the chemical sciences in all senses of the word, it is a duty, but also a pleasure to follow the development in chemical research closely with the aim of spotting pioneering work and new trends as early as possible. In doing so, it became abundantly clear that the young chemists were about to become more important for the future of our science than they were just a decade or so ago. For chemistry, it is therefore important to encourage our young colleagues in their work, and IUPAC does so through the IUPAC Prize for Young Chemists. This prestigious annual prize honors 4-5 chemists with a fresh Ph.D. for exceptional work during their Ph.D. studies. The work is mainly judged on the basis of a 1000-word essay which is supported by recommendations from the senior scientist(s) with whom the candidate collaborated. As immediate Past President of IUPAC, I had the pleasure of chairing an international prize selection committee of eminent chemists with a wide range of expertise in chemistry that adjudicated essays from 49 applicants from 19 countries. To pick the winners was not an easy task, because there were many outstanding candidates, but at the end the committee arrived at a unanimous decision and awarded the 2006 IUPAC Prize to the following young chemists: Michelle Nena Chrétien , University of Ottawa, Ontario, Canada, with a thesis entitled "Photochemical, photophysical, and photobiological studies of zeolite guest–host complexes" Valentina Domenici , University of Pisa, Italy, with a thesis entitled "Structure, orientational order and dynamics of rod-like and banana-shaped liquid crystals by means of 2 H NMR: New developments" Matt Law , University of California, Berkeley, CA, USA, with a thesis entitled "Oxide nanowires for sensing, photonics and photovoltaics" Emilio M. Pérez , University of Edinburgh, UK, with a thesis entitled "Hydrogen-bonded synthetic molecular machines" Dunwei Wang , Stanford University, CA, USA, with a thesis entitled "Synthesis and properties of germanium nanowires" Each of the winners will receive both a cash prize of USD 1000 and a free trip to the 41st IUPAC World Chemistry Congress, which will take place in Turin, Italy, 5-11 August 2007. Here the winners will have the opportunity to present their work, which is an important stage of any research project. But to reach an even wider audience, the prizewinners have been invited to submit manuscripts on aspects of their research for publication in Pure and Applied Chemistry . It is therefore a pleasure to see that four refereed papers, containing critical reviews of high quality, appear in this issue of PAC . It is a great pleasure to congratulate each of the winners (and their supervisors) with the 2006 IUPAC Prize. It is IUPAC's hope that each winner is encouraged to continue to do exciting research that will contribute to a bright future for the molecular-based sciences, which are so important for our common future. Leiv K. Sydnes IUPAC Immediate Past President and Chairman of the IUPAC Prize Selection Committee

Zeolites are nanoporous, crystalline aluminosilicate materials comprised of a series of strictly uniform channels and cavities repeating along the tri-directional structure of the lattice. Over the last 30 years, researchers have increasingly recognized the desirable properties of these materials as hosts for photochemical reactions. This review will endeavor to draw attention to the properties of zeolite materials that make them appealing substrates for hosting guest molecules during photochemical reactions. An overview of some classical examples in zeolite host-guest photochemistry will be presented along with a brief description of a new use for zeolite materials as protective encapsulators.

Deuterium NMR spectroscopy is a very powerful technique for studying partially or totally ordered systems, such as liquid crystals (LCs) and polymers. LCs represent a branch of the most general class of soft materials, with peculiar physical and chemical properties which attracted scientific attention for their potentiality for technological applications. From a chemical point of view, there are three aspects in which 2 H NMR could provide significant insights: (i) the conformational and structural properties; (ii) the molecular dynamics and mobility; and (iii) the orientational order and aggregation/distribution of molecules in the different liquid-crystalline phases. In this work, some of the recent developments in this field are discussed, focusing on two main topics: (1) the molecular dynamics of the smectic liquid-crystalline phases formed by rod-like molecules and (2) the unusual orientational and dynamic properties of the new liquid-crystalline mesophases formed by banana-shaped molecules (BLCs).

Stimuli-responsive molecular shuttles are rotaxanes in which the macrocycle can be translocated from one position on the thread to a second site in response to an external trigger. Here, we present a brief overview of the contributions of the Leigh group to the field from 2001 to 2006. In this short period of time, molecular shuttles have moved from little more than laboratory curiosities to truly functional molecular machines.

As a promising electronic material, Ge nanowire (GeNW) has attracted much attention for its low band gaps, high mobilities, and unprecedented dimensions. This article reviews recent research and advancement on this topic and summarizes many aspects of GeNWs, including preparation, surface chemistry, physical properties, functional devices, and controlled assembly. It is shown that GeNWs can be readily synthesized by chemical methods and their electronic properties are comparable or superior to that of the bulk counterparts. Studies of surface chemistry have revealed dominant roles of surfaces on nanowires, and this result led to successful passivations toward air-stable, high-performance functional devices. Finally, controlled assembly to organize chemically synthesized nanowires into functional structures is discussed. Doors are opened up to widely utilize this novel material as excellent electronic building blocks.

An explanation of the origin and interpretation of the suspension effect (SE) is presented in accordance with "pH Measurement: IUPAC Recommendations 2002" [ Pure Appl. Chem. 74 , 2169 (2002)]. It is based on an analysis of detailed schemes of suspension potentiometric cells and confirmed with experimental results. Historically, the term "suspension effect" evolved during attempts to determine electrochemically the thermodynamically defined activity of H + (aq) in suspensions. The experimental SE arises also in determining other pIon values, analogous to pH values. The SE relates to the observation that for the potential generated when a pair of electrodes (e.g., reference electrode, RE, and glass electrode) is placed in a suspension, the measured cell voltage is different from that measured when they are both placed in the separate equilibrium solution (eqs). The SE is defined here as the sum of: (1) the difference between the mixed potential of the indicator electrode (IE) in a suspension and the IE potential placed in the separated eqs; and (2) the anomalous liquid junction potential of the RE placed in the suspension. It is not the consequence of a boundary potential between the sediment and its eqs in the suspension potentiometric cells as is stated in the current definition of the SE.

The measured cell potentials for suspension potentiometric cells have been interpreted and explained by a detailed analysis of the schemes for these cells ["Guidelines for potentiometric measurements in suspensions. Part A. The suspension effect (IUPAC Technical Report", Pure Appl. Chem. 79 , 67 (2007)]. Some former disagreements amongst investigations have been clarified. A new unambiguous operational definition of the suspension effect (SE) is presented. It is defined as the difference in cell potential for two suspension potentiometric cells, one with both electrodes in the separated equilibrium solution (eqs) and the other with both electrodes in the sediment or suspension. This potential difference is the sum of the change in the indicator electrode (IE) potential and the change in the liquid junction potential of the reference electrode (RE), when the electrodes are used for measurement, once in the sediment of the suspension and then in its eqs.

This document describes the introduction of the concept of property in the field of clinical and environmental human toxicology for the presentation of results of clinical laboratory investigations. It follows the IFCC-IUPAC systematic terminological rules and attempts to create a common base for communication between the clinical chemist, the medical practitioner, the human toxicologist, and the environmental toxicologist. The term designating a substance being a toxicant may be an international nonproprietary name (INN), a generic name, a registered trade name, a fantasy name, or other. This causes difficulties in the transmission of requests and reports on properties involving substances in biological fluids and environmental media to and from laboratories, to the end user, and in the collating of this information from different sources. The document comprises a list of properties of human and environmental systems involving toxicants for use in transmitting medical laboratory data. The document recommends terms based on the format developed by the IFCC and IUPAC to facilitate interaction between disciplines and unambiguous interpretation of data, e.g., for purposes of risk interpretation. Systematic terms are presented together with a code (identified by the letters NPU) for each. The complete CNPU Database may be found at http://dior.imt.liu.se/cnpu/info.htm.