Vol. 103 No. 4 (2007)

Since the discovery of C60 fullerene, carbon-based nanostructures became one of the hottest research topics in science. During the past decade research efforts were mainly devoted to the investigation of C60 and carbon nanotubes, although the ability of carbon to exist in different allotropic forms has provided a variety of nanoscale size shapes with fascinating properties. In this article we highlight some of the most representative examples that document the scientific progress accomplished in this field which, surprisingly, started with a serendipitous discovery.

The paper gives a description of the well-known SRK (Soave-Redlich-Kwong) equation of state. Some drawbacks of its original form are evidenced and some important modifications of it are suggested in order to improve it.

The development of synthetic receptors based in supramolecular chemistry concepts will not allow a selective molecular recognition. A more simple, convenient and innovative approach relies on the use of organic-inorganic hybrid materials. These hybrid materials will be prepared by the grafting of certain synthetic receptors onto porous inorganic solids. The grafting of these coordinating systems onto a solid support leads to synergic effects that are hardly achievable with only the synthetic receptors or the solids alone. The presence of these synergic effects suggests that these organic-inorganic hybrid materials will be used for the development of novel sensory systems and novel molecular and/or ionic recognition protocols.

Electrochromism is defined as the ability of a material to reversibly and continuously change its colour by means of an electrochemical reaction. In the present article the most relevant applications of these materials are described, together with the colour change process, the most widely employed organic electrochromic materials (conducting polymers) and the device assembling process. Limitations and perspectives of this technology in a near future are also discussed, in the fields of image generation as well as domotics.

The Nobel Prize in Chemistry 2007 has been awarded to Gerhard Ertl, a German scientist 71 years old, with an enormous prestige, kind personality and exceptionally talented. At the end of the 70's, Ertl pioneered the introduction of extremely sophisticated techniques to investigate the interaction of molecules with solid surfaces. The monocrystalline surfaces under investigation were encapsulated in an ultra high vacuum camera and isolated from the atmosphere.

The aim of this work is the application of an experimental activity that employs a different strategy in order to get a deeper insight in the study of the properties of ionic substances and their crystals. In the present article the following experimental activities are proposed: a simple method to obtain monocrystals of NaCl prepared from culinary salt, the use of Archimedes' principle with the purpose of the determination of its density and the use of the cell parameters of the cubic crystalline system of NaCl and related salts to calculate their densities.

: The separation of photosynthetic pigments by paper chromatography in general and those of the spinach in particular, frequently is explained on the basis of its differences of solubility. This incorrect explanation, next to the perception of a methodology considered like an authentic and pure partition between two inmiscible liquid phases, shows the necessity to analyze and clarify the conceptual framed complex that sublies after the apparent simplicity of this classic laboratory practice. The theoretical and experimental foundations that allow to explain part of this complexity are presented, in this article, with purpose of causing more coherent explanatory models with the involved phenomena.

A. Lavoisier, C. L. Berthollet y H. Davy enjoy a significant place in the history of chemical theory. A closer examination of all their contributions reveals that they played as well an important role in fields properly related to practical issues. This wide range of occupations was something assumed by a great number of chemists of the period considered in this study, the second half of the XVIIIth Century and the beginning of the XIXth Century. Thus the paper will focus on offering details of the areas that drew the attention of relevant chemists of the period mentioned and on the ideas that legitimize their labours.

Some representative cases of the scientific controversies that led to consolidate Chemistry in 19th century and to establish the present theories, are studied. Polemics related with combination laws, chemical symbols, beginnings of structural theory, and real existence of atoms and molecules, are especially analysed. The global study of these controversies shows both dialectic (with opposition of contraries) and dialogue (with complementary entities) contradictions and suggests that one of the central problems to be accomplished by Chemistry was the full acceptance of the atomic and molecular nature of matter.

Keywords: Scientific controversies, combination laws, chemical symbols, structural theory, atomism

The contribution of Spain to the discovery of new elements of the Periodic Table is modest but significant (two and a half). We conclude that Spain is, also in this respect, a normal European country. The discovery of platinum, vanadium and tungsten is illustrated with historic and cultural details.

Keywords: periodic table, Mendeléiev, isotopes, platinum, vanadium, tungsten