The solution/solid state luminescence properties of selected orthometalated palladium complexes have been investigated in parallel with the relevant structural information provided by their X-ray crystal structures and theoretical calculations. Two cyclometalated backbones with different stacking abilities and a selection of bridging O^O, O^N or N^S ligands comprise the series under study, [{Pd(μ-L) (C^N)}2] (C^N = N-phenylpyrazole (Phpz) ; N-benzylideneaniline (Bza) ; L = acetate (Aco) , succinimidate (succ) , phthalimidate (phthal) , 1-methylimidazoline-2 thionate (Smeimid) ), completed with mononuclear [Pd(C^N)(N-pClPhsal)] (N-pClPhsal = chlorophenylsalycilaldiminate) complexes. New compounds , and were synthesized and the X-ray structures of , , , and have been elucidated in order to examine and compare solid-state Pd(C^N)-Pd(C^N) and ligand-ligand interactions with the rest of the series. The molecular structures of the complexes reveal intramolecular PdPd distances between 2.842 and 2.999 Å and π-π and C-Hπ interactions. All complexes studied show emission in the solid state at room temperature and a relationship is observed between emission energy, the nature of the lowest energy excited state, and metal-metal interactions. DFT calculations are undertaken to gain insight into the relationship between the structure and photophysical properties of the complexes.
El presente estudio tiene como objetivo conocer las principales ideas de alumnos de educación secundaria en relación con la Herencia Biológica antes de estudiarla y comprobar si se modifican después de haber recibido una enseñanza del tema de manera tradicional. La población de estudio está formada por alumnos de 4º de ESO de un instituto de enseñanza secundaria de la Región de Murcia y el instrumento de recogida de información ha sido un cuestionario. Los resultados muestran que, en general, los estudiantes tienen conocimientos sobre contenidos elementales de Genética antes incluso de tener el primer contacto académico con ellos y que, si no son tenidos en cuenta, pueden dificultar sus aprendizajes. También ponen de manifiesto que algunas de estas ideas no se modifican sustancialmente después de estudiar los contenidos sobre Herencia Biológica. Las principales implicaciones educativas nos llevan a enfocar el proceso de enseñanza/aprendizaje de la Genética de manera que las actividades tengan en cuenta las ideas de los alumnos.Palabras clave: Ideas previas; aprendizaje; herencia biológica; educación secundaria. Knowledge of high school students on biological inheritance: implications for teachingThe objective of this investigation is to know the main ideas students of secondary education have in relation with Biological Inheritance before they study it and to check whether this knowledge changes after receiving a traditional teaching of the contents. The study population was formed by students from the 4th year of Secondary Education in a high school from Region of Murcia and the instrument for collecting information was a questionnaire. The results show that, in general, students have some prior knowledge about elementary contents of Genetics even before having the first academic contact with them. This can make learning difficult if it is not taken into account. Moreover, the results show that some of these ideas do not change substantially after they study the contents of Biological Inheritance. The main educational implications lead us to focus the teaching/learning process of Genetics in a way that the activities take into account the prior ideas of the students.Keywords: Previous ideas; learning; biological inheritance; secondary education.Para citar este artículo: Ruiz González C., Banet E. y López Banet L. (2017) IntroducciónLa enseñanza de la Herencia Biológica resulta básica para la alfabetización científica y tecnológica de los ciudadanos, ya que son numerosos los contextos sociales en los que la Genética es la protagonista: clonación de animales, alimentos transgénicos, enfermedades de origen genético… (Puigcerver e Íñiguez, 2013).Las ideas previas en relación con la Herencia Biológica de los seres vivos son condicionantes en el aprendizaje de conocimientos relacionados con la Genética, uno de los temas que plantea mayores dificultades en el proceso formal de enseñanza-aprendizaje de la biología (Abril, Mayoral y Muela, 2004). El docente ha de conocerlas y tenerlas en cuenta durante el proceso de en...
The reaction of benzazole ligands 2-(2'-hydroxylphenyl)benzimidazole (Hpbm), 2-(2'-hydroxylphenyl)benzoxazole (Hpbx), and 2-(2'-hydroxylphenyl)benzothiazole (Hpbt), with [Ni(Tp*)(μ-OH)]2 (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate), leads to pentacoordinate nickel complexes [Ni(Tp*)(pbz)] (pbz = pbm (1), pbx (2), pbt (3)). The structures of 1, 2, and 3 were determined by X-ray crystallography. The pentacoordinate nickel complexes have distorted trigonal bipyramidal geometries with Addison's τ parameter values of 0.63, 0.73, and 0.61 for 1, 2 and 3, respectively. The benzazolates are bonded in an η(2)(N,O) fashion to the nickel atoms. DFT calculations are carried out to optimize the structures of the three complexes giving a good agreement with the X-ray structures. The (1)H NMR spectra of complexes 1-3 exhibit sharp isotropically shifted signals. The complete assignment of these signals required an application of two-dimensional {(1)H-(1)H}-COSY techniques. The experimental absorption spectra of the three complexes in chloroform solution each show an intense absorption band in the ultraviolet region ca. 240 nm, followed by three less intense bands, the first two at ∼295 and ∼340 nm, and the last more disperse one, at wavelengths between 360 and 410 nm. The absorption spectra are simulated by TD-DFT and reproduce the main features of the experimental spectra well. The analysis of the electronic transitions by inspection of the frontier molecular orbitals and also the natural transition orbitals allowed us to characterize and assign the observed bands properly. The three complexes are moderately blue luminescent at room temperature, both in the solid state and in solution. Emission spectra at room temperature display broad structureless bands in chloroform solution at 460, 482, and 512 nm for complexes 1, 2 and 3, respectively, and structured emission in solid state with λmax values of 473, 486, and 516 nm. Complexes containing different donor atoms in the benzazole ligand are furthermore observed to give different luminescence responses in the presence of Zn(II), Cd(II), Hg(II), and Cu(II).
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