Video Experimental Relacionado
Updated: Jul 6, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Agrupaciones desnudas de 56 átomos de estaño en estado sólido
1Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
Journal of the American Chemical Society
|March 28, 2002
Resumen
Los investigadores descubrieron gigantescos grupos de estaño aislados de 56 átomos dentro de un nuevo compuesto de bario-sodio-estaño. Este hallazgo representa el mayor cúmulo desnudo de grupo principal en estado sólido, excluyendo los fullerenos.
Área de la Ciencia:
- Química del estado sólido.
- Química inorgánica y inorgánica.
- Ciencia de los materiales ciencia de los materiales.
Sus antecedentes:
- Los clústeres de estaño son de gran interés debido a sus propiedades electrónicas y estructurales únicas.
- Las investigaciones anteriores se han centrado en grupos de estaño más pequeños o en aquellos encapsulados dentro de otros materiales.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos compuestos ternaros que contienen grandes grupos de estaño.
- Para investigar la estructura y la unión de estos grupos de estaño recién descubiertos.
Principales métodos:
- Fusión directa del bario elemental, el sodio y el estaño a 800 grados C.
- Difracción de rayos X de un solo cristal para la determinación estructural del compuesto Ba{16) Na{204) Sn{310).
Principales resultados:
- Descubrimiento de grupos aislados y gigantescos de estaño ([Ba(4)@Sn(56)](36-)) compuestos de 56 átomos de estaño, que se asemejan a un fullereno cóncavo.
- El cúmulo está formado por cuatro dodecaedros pentagonales de cara fusionada y está estabilizado por cuatro cationes de bario.
- Esto representa el mayor grupo principal de cúmulo desnudo encontrado en estado sólido, excluyendo los fullerenos.
- Otros grupos de estaño, incluyendo Sn 16 n y Sn 8 , también fueron identificados en la estructura.
Conclusiones:
- La síntesis de Ba ((16) Na ((204) Sn ((310) proporciona una ruta a nuevos y grandes grupos de grupos principales en el estado sólido.
- El cúmulo descubierto [Ba(4)@Sn(56)](36-) amplía nuestra comprensión de la química del cúmulo más allá de los fullerenos.
- Este trabajo abre nuevas vías para explorar las propiedades y aplicaciones potenciales de materiales complejos a base de estaño.
Videos de Conceptos Relacionados
01:52Atomic Mass
Atoms — and the protons, neutrons, and electrons that compose them — are extremely small. For example, a carbon atom weighs less than 2 × 10−23 g. When describing the properties of tiny objects such as atoms, we use appropriately small units of measure, such as the atomic mass unit (amu). The amu was originally defined based on hydrogen, the lightest element, then later in terms of oxygen. Since 1961, it has been defined with regard to the most abundant isotope of carbon, atoms of which are...
03:26Electron Configuration of Multielectron Atoms
The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3s orbital, giving a 1s22s22p63s1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n) are called valence electrons, and those occupying the inner shell orbitals are called core electrons. Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron...
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
03:20Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
01:03Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.