Supramolecular Organic and Organometallic Chemistry Centre

Abstract
The project aims to obtain a new generation of metal-organic frameworks (MOFs) using novel families of made-by-design spacers (Cyclophane and cyclophane-like spacers with pre-formed cavities; C3-symmetry cryptand-based ligands; Tetrahedral synthons; Organometallic spacers featuring robust metal-carbon bonds, e.g. Organometallic halides, with appropriate organic groups attached to the metal centre to provide stability of the organometallic unit and/or potential to develop 3D architectures. The efforts will be concentrated towards compounds with the metal in lower oxidation state bearing a lone pair of electrons and thus higher reactivity). The construction of MOFs using organometallic tectons is a field largely unexplored. A special emphasis will be given to the post-synthesis processing of the MOFs (removal of solvent and weakly coordinated ligands; functionalization of selected MOFs by nanoconfinement with metal nanoparticles and functionalization for generation of acidic and basic sites). The sorption of various gases (H₂, CO₂, C₂H₂, etc.) as well the catalytic properties of the newly synthesized MOFs will be investigated. Enantioselective organic reactions catalyzed by chiral MOFs will be studied as well. In this scope MOFs functionalized with acid and base functions will be investigated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solvent-free conditions. The luminescence properties of some MOFs as well as the influence of the host molecules on the luminescence (especially for those containing lanthanide cations) will be investigated. The ability of the new MOFs for decontamination processes will be tested - more specifically, MOFs will be used as adsorbents for the molecules resulted from the degradation of pharmaceutical compounds via either liquid phase catalytic oxidation or plasma.

Main objectives
A. Design, synthesis and characterization of new families of organic spacers as precursors of metal-organic frameworks with desired network topologies.
B. Design, synthesis and characterization of new organometallic spacers and potential organometallic nodes.
C. Building MOFs based on the newly designed and synthesized organic and organometallic spacers.
D. Optimization of MOFs architectures based on the design improvement of new spacers and organometallic nodes.
E. Optimizing MOFs properties by post-synthesis processes.
F. Generation of acidic and basic sites in MOFs showing optimized properties by nanoconfinement with metal nanoparticles and post-synthetic functionalization.
G. Evaluation of selective sorption capacity of MOFs for various molecules.
H. Investigation of gas (hydrogen) storage capability of synthesized MOFs for energy applications.

Results 2012 - 2013

Team 2 is involved in the work for the fulfillment of objectives A, C, D and E. In 2012-2013 many reactions were carried out in order to obtain cryptands and cyclophanes as spacers, or to prepare ligands with tetrehedral symmetry.
Various cryptands were obtained using compounds with C3 symmetry (Schemes 1-3). The structures of the compounds were investigated by NMR, MS and single crystal X-ray diffraction. Two papers were submitted with these results.
Many compounds with adamantane or spirofluorene core were obtained. The compounds were decorated with groups which have a high ability for complexation or with groups which can further react in order to give organometallic frameworks. The intermediates for bidimensional ligands (bearing anthracene units) were also obtained and the preparation of the appropriately decorated compounds (with groups which have a high ability for complexation or with groups which can further react in order to give organometallic frameworks) is running. Some ligands with C3 development of the coordination were already obtained starting from terpyridine derivatives and some promising results in the construction of MOFs were already obtained with these ligands.


Articles

1. Cryptands with 1,3,5-Tris(1',3'-Dioxan-2'-yl)-Benzene Units: Synthesis and Structural Investigations.
   Cîrcu, M.; Soran, A.; Hadade, N. D.; Rednic, M.; Terec, A.; Grosu, I. J. Org. Chem. 2013, 78, 8722-8729
   
   
2. Synthesis of cryptands with di-yne units by the acetylenic homocoupling reaction of some C3 symmetry tripodands.
   Pascanu, V.; Cîrcu, M.; Socaci, C.; Terec, A.; Soran, A.; Grosu, I. Tetrahedron Lett., 2013, 54, 6133-6136.