Enrique González Vergara

The supramolecular structure of pyridine-2,6-dicarboxylic acid

The structure of pyridine-2,6-dicarboxylic acid, C(7)H(5)NO(4), has been determined at 0.71 A resolution. The molecule is located on a site with mirror symmetry. A one-dimensional supramolecular structure is stabilized in the solid state through a strong symmetric double hydrogen bond, with H* * *O distances of 1.86 (3) A and O-H* * *O angles of 167 (3) and 171 (5) degrees. This arrangement is similar but not identical to that reported for the isoelectronic isophthalic acid (benzene-1,3-dicarboxylic acid).

De aulas visibles e invisibles y hasta inteligentes

Abstract In a world where more than a fifth of the population has internet connectivity and that amount is increasing constantly in giant steps, classrooms cannot keep being just the same. More and more schools and universities are giving virtual learning environments to their students. In the specific case of teaching Chemistry, this has become a challenge given the experimental nature of this science; however, it is possible to build an intelligent classroom-laboratory by making some changes to a conventional classroom. In this work we present five examples in which schools are making efforts to change the traditional model based only in the teacher-student relationship to one in which the classroom plays a fundamental role. Some important aspects of the relevance of visible classrooms are also included.

Un tetraedro o un tetraedro alargado a partir de un popote y un cordel

The construction of a regular (or an elonged) tetrahedron model from a plastic straw and a cord is described. These models can be used for teaching stereochemistry of tetrahedral compounds and allenes, respectively.

Geometría, Simetría y Química. Un modelo de icosaedro hecho con popotes de plástico

La quimica como ciencia netamente molecular requiere la explicacion a escala macroscopica de los fenomenos microscopicos. A este respecto, el uso de modelos moleculares en la ensenanza y en la investigacion juega un importante papel. La quimica de boranos, carboranos y cumulos metalicos no es la excepcion; sin embargo, casi no existen modelos simples de desarrollar que sean capaces de representar a muchas de tales moleculas.