Modulare Synthese von funktionellen nanoskaligen Koordinationspolymeren

Abstract

Die koordinativ vermittelte Organisation von Metallionen und organischen Brückenliganden liefert Hybridmaterialien mit vielversprechenden Eigenschaften für Anwendungen etwa in der Gasspeicherung und heterogenen Katalyse. Eine besondere Klasse von Hybridmaterialien sind die Koordinationspolymere. In diesem Kurzaufsatz betrachten wir jüngste Entwicklungen bei der Synthese von amorphen und kristallinen nanoskaligen Koordinationspolymeren und zeigen, dass die Maßstabsverkleinerung in den Nanometerbereich zu breiten Anwendungsmöglichkeiten führt, z. B. in der Katalyse, für Spin‐Crossover‐Materialien, zur Verwendung als Templat, in der Biosensorik, der biomedizinischen Bildgebung und im Wirkstofftransport. Die Ergebnisse unterstreichen das Potenzial funktioneller Nanomaterialien aus molekularen Komponenten.

Photoisomerization of a Maleonitrile‐Type Salen Schiff Base and Its Application in Fine‐Tuning Infinite Coordination Polymers

“…Coordination between metal ions and carboxylate-functionalized ligands is well-known in transition metal coordination chemistry, and it can be characterized by IR spectroscopy. [20,21,24] On coordinating with Zn II , deprotonation of the carboxyl group results in a decrease in C=O stretching frequency from 1672 cm À1 for the precursor (2Z) to 1618 cm…”

“…Hybrid materials have been built from metal ions and polydentate bridging ligands, of which salen-type ligands are among the most common building blocks. [20,21] Because of their appropriate coordinating functionalities (COOH), we propose that 2Z (2E) with its intrinsic structure-building motif would be a suitable template to demonstrate as well as to differentiate maleonitrile E/Z conformers leading to different coordination polymers with transition metal ions as nodes. As depicted in Scheme 1, a condensation process [8,9] involving cis-diaminomaleonitrile and 3-formyl-4-hydroxybenzoic acid [22] in methanol afforded 2Z by syn addition, as evidenced by the 1 H NMR spectrum (Figure 7 A, see Experimental Section for further characterization).…”

Nanoscale Light‐Harvesting Metal–Organic Frameworks

“…[12] Recently, increasing interest has been paid to the miniaturization of MOFs to the nanometer scale; these miniaturized coordination polymers can overcome, to some extent, the limited solution-based behavior of their corresponding bulk materials. [13] The so-called nanoscale coordination polymers [13] have potential applications such as ion exchange, [14] multimodal bioimaging, [15] drug delivery, and sensing. [16] Recent studies showed that some fluorescent molecules confined in coordination polymer nanoparticles by novel adaptive self-assembly or host-guest strategies exhibit remarkably enhanced fluorescence and/or efficient FRET.…”

“…[1] However, the arrangement of different components into long-range ordered frameworks is challenging. [13] Owing to different intermolecular forces in the precursor solution, such as counter ionic interactions, hydrogen bonding, and p-p interactions, coordination polymers easily aggregate to form amorphous particles. Recently, crystalline NMOFs have been prepared by surfactant-assisted processes or by approaches combining surfactants with hydrothermal techniques, microwave, or ultrasonication.…”

“…XRD data reveal that the sample has a highly ordered hexagonal structure (Figure 1 c). Seven fine reflexions (d spacings: 3.365, 1.948, 1.672, 1.265, 1.121, 0.968, 0.923 nm) correspond to the squared spacing ratios 1, 3,4,7,9,12,13, and to the indexing (hk) = (10), (11), (20), (21), (30), (22), (31), respectively. [21] HRTEM images are shown in Figure 1 d. The distance between two adjacent pore centers is approximately 3.3-3.5 nm, which is comparable to that of Eu-L1.…”