Zeolite-based chiral ion-exchangers for chromatographic enantioseparations and potential applications in membrane separation processes.

Chiral resolution of racemic compounds represents an important task in research and development and, most importantly, in the large-scale production of pharmaceuticals. Zeolites, which are already frequently utilized for their unique properties, represent materials that can be used for the development of new chiral stationary phases for liquid chromatography, simulated moving bed or enantioselective membranes. The aim of this study was to modify a series of MWW zeolites by a chiral anion-exchange type selector thereby creating a chiral stationary phase for enantiomeric resolution of acidic compounds.

Reverse ADOR: reconstruction of UTL zeolite from layered IPC-1P.

The assembly-disassembly-organisation-reassembly (ADOR) process has led to the discovery of numerous zeolite structures, albeit limited to materials with decreased pore size in relation to the parent germanosilicate zeolite. This limitation stems from the rapid decrease in -spacing upon hydrolysis (disassembly). Nevertheless, we have artificially increased the -spacing of layered IPC-1P by intercalating organic species.

Exploring the "Goldilocks Zone" of Semiconducting Polymer Photocatalysts by Donor-Acceptor Interactions.

Water splitting using polymer photocatalysts is a key technology to a truly sustainable hydrogen-based energy economy. Synthetic chemists have intuitively tried to enhance photocatalytic activity by tuning the length of π-conjugated domains of their semiconducting polymers, but the increasing flexibility and hydrophobicity of ever-larger organic building blocks leads to adverse effects such as structural collapse and inaccessible catalytic sites. To reach the ideal optical band gap of about 2.

Post-Synthesis Stabilization of Germanosilicate Zeolites ITH, IWW, and UTL by Substitution of Ge for Al.

Germanosilicate zeolites often suffer from low hydrothermal stability due to the high content of Ge. Herein, we investigated the post-synthesis introduction of Al accompanied by stabilization of selected germanosilicates by degermanation/alumination treatments. The influence of chemical composition and topology of parent germanosilicate zeolites (ITH, IWW, and UTL) on the post-synthesis incorporation of Al was studied.

Combined PDF and Rietveld studies of ADORable zeolites and the disordered intermediate IPC-1P.

The disordered intermediate of the ADORable zeolite UTL has been structurally confirmed using the pair distribution function (PDF) technique. The intermediate, IPC-1P, is a disordered layered compound formed by the hydrolysis of UTL in 0.1 M hydrochloric acid solution.

The effect of the zeolite pore size on the Lewis acid strength of extra-framework cations.

The catalytic activity and the adsorption properties of zeolites depend on their topology and composition. For a better understanding of the structure-activity relationship it is advantageous to focus just on one of these parameters. Zeolites synthesized recently by the ADOR protocol offer a new possibility to investigate the effect of the channel diameter on the adsorption and catalytic properties of zeolites: UTL, OKO, and PCR zeolites consist of the same dense 2D layers (IPC-1P) that are connected with different linkers (D4R, S4R, O-atom, respectively) resulting in the channel systems of different sizes (14R × 12R, 12R × 10R, 10R × 8R, respectively).

Synthesis of 'unfeasible' zeolites.

Zeolites are porous aluminosilicate materials that have found applications in many different technologies. However, although simulations suggest that there are millions of possible zeolite topologies, only a little over 200 zeolite frameworks of all compositions are currently known, of which about 50 are pure silica materials. This is known as the zeolite conundrum--why have so few of all the possible structures been made? Several criteria have been formulated to explain why most zeolites are unfeasible synthesis targets.

Layer like porous materials with hierarchical structure.

Many chemical compositions produce layered solids consisting of extended sheets with thickness not greater than a few nanometers. The layers are weakly bonded together in a crystal and can be modified into various nanoarchitectures including porous hierarchical structures. Several classes of 2-dimensional (2D) materials have been extensively studied and developed because of their potential usefulness as catalysts and sorbents.

The ADOR mechanism for the synthesis of new zeolites.

A novel methodology, called ADOR (assembly-disassembly-organisation-reassembly), for the synthesis of zeolites is reviewed here in detail. The ADOR mechanism stems from the fact that certain chemical weakness against a stimulus may be present in a zeolite framework, which can then be utilized for the preparation of new solids through successive manipulation of the material. In this review, we discuss the critical factors of germanosilicate zeolites required for application of the ADOR protocol and describe the mechanism of hydrolysis, organisation and condensation to form new zeolites starting from zeolite UTL.

Atomic force microscopy of novel zeolitic materials prepared by top-down synthesis and ADOR mechanism.

Top-down synthesis of 2D materials from a parent 3D zeolite with subsequent post-synthetic modification is an interesting method for synthesis of new materials. Assembly, disassembly, organisation, reassembly (ADOR) processes towards novel materials based on the zeolite UTL are now established. Herein, we present the first study of these materials by atomic force microscopy (AFM).