Organometallic compounds can also form porous structures and have greatly broadened the palette of porous materials, though until now these have been limited to species with very small pores. In the journal Angewandte Chemie, Korean researchers led by Jaheon Kim now report the synthesis and characterization of a mesoporous organometallic lattice with cagelike pores that are 3.9 to 4.7 nm in diameter.
Previously, only a few stable structures made of metal atoms or ions and organic ligands have been made that have larger pores, called mesopores (>3 nm in diameter). Among the reasons for this is the special type of bonding that takes place between a metal and a ligand, known as complex coordination. Large cavities can easily destabilize this type of lattice. Just as difficult as the synthesis of such structures is their characterization at the atomic level. The Korean researchers have overcome both challenges. Their lattice structures are made of ions of the rare-earth metal terbium and an organic ligand. By using X-ray crystallographic methods, the scientists were also able to precisely determine the structures of both the crystal and the pores.
The use of nitrogen adsorption measurements also allowed them to confirm that there are two types of pore in the structure, some a little bigger, some smaller. When the samples are activated at 160 °C, the specific surface area of the porous crystals increases further, but its sorption ratio does not change. This behavior is also confirmed in adsorption experiments with carbon dioxide.
When irradiated with light, the crystals fluoresce green. They are very thermally stable and hold out well enough in a vacuum to be loaded up by means of a sublimation process with guest molecules that are catalytically active or useful for optoelectronics. The researchers tested this with ferrocene, a molecular “sandwich” with two aromatic five-membered rings acting as the “bread” and an iron atom as the “filling”. With ferrocene guests in its pores, the crystal no longer fluoresces green. Instead, emission from the ferrocene is observed. The researchers believe that the crystal lattice absorbs the photons like an antenna and passes them on to the ferrocene unit in the form of “energy bundles”. The ferrocene molecule in turn gives off this energy in the form of light. However, its emission is stronger than that given off in the irradiation of ferrocene alone. Systems using this construction principle could be useful for future optoelectronic components such as novel light-emitting diodes.
Author: Jaheon Kim, Soongsil University, Seoul (Korea), mailto:email@example.com
Title: Crystal Structure and Guest Uptake of a Mesoporous Metal-Organic Framework Containing Cages of 3.9 and 4.7nm in Diameter
Angewandte Chemie International Edition, doi: 10.1002/anie.200702324
Jaheon Kim | Angewandte Chemie
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering