Conférence LCC
Pr Vladislav V. Krisyuk
Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russie
Volatile supramolecular structures based on heterometallic coordination polymers
Jeudi 25 octobre 2018 à 10h30 Auditorium Fernand Gallais
Campus CNRS 205
205, route de Narbonne, Toulouse
Contacts LCC: Eric Manoury, eric.manoury@lcc-toulouse.fr
Retrouvez le programme complet des séminaires sur le site web du LCC : http://www.lcc-toulouse.fr/
Dr. Vladislav Krisyuk
Nikolaev Institute of Inorganic Chemistry SB RAS Lavrentiev Ave. 3, Novosibirsk, 630090, Russian Federation
Construction and characterization of coordination polymers continue to attract much attention owing to their potential application in catalysis, separations, photochemistry and electromagnetism. One-, two- or three-dimensional coordination polymers have attracted much interest in the context of the so called metal–organic frameworks (MOFs), consisting of metal ions and oligodentate ligands that form networks. But little is known about their volatility. A useful strategy to the rational synthesis of such volatile compounds consists in the use of molecular building blocks. The nature of the molecular building blocks as well as the type of intra- and intermolecular interactions play an important architectural role in the design of volatile supramolecular systems and have a significant impact on their properties. Revealing and control of the factors that govern the relationship of crystal design and properties in these polymolecular systems have long been one of the central issues in the design of new materials with desired properties. For the synthesis of these structures it is proposed to use metallorganic compounds which prone to form polymolecular products. Metal -diketonate derivatives is very promising class of metal complexes being volatile and tending to form coordination polymers in the form of complex chains or networks of molecules connected by weak bonds ('soft bonds').
It is shown that the degree of association of molecules depend on the type of substituent in the ligand. Those combinations allow heterocomplex compounds of multinuclear chains, layers and discrete structures through the bridging donor atoms of the ligands.
Such heterometallic structures are held together by Lewis acid-base interactions between metal atoms and donor atoms of ligands.
As the initial complexes, these heterometallic compounds are volatile and sublimate on heating in vacuum. Their structural diversity, thermal behaviour and the ability to sublimate retaining their composition and suprastructure largely depend on the structure of ligands in the composition of the initial complexes. Such complex molecular compounds can be formed by noncovalent interactions of other types. We found that molecules of different metal complexes may be bound by closed-shell interactions between specific groups in terminal substituents of the ligands and central atoms and even by very exotic metallophilic interactions. In parallel with volatility and solubility such complexes demonstrate interesting magnetic and optical properties. Cocrystallization of individual complexes in organic solvents is very good method for the synthesis of new heterometallic compounds. In such manner we can combine a great number of metals and organic ligands that was successfully demonstrated with -diketonates and ketoiminates as models. This approach provided a systematic study of large number of heterocomplexes depending on the nature of the metal and the ligand structure. XRD methods are used to determine their crystal structure. Volatility of the new compounds can be checked by methods of complex thermal analysis and vacuum sublimation. Particular attention is paid to the study of the gas phase. The composition of the gas phase is studied in detail by mass spectrometry. DFT calculations of electronic structure of molecules, fragments and lattices can help to explain observed structures and predict new ones and their properties. A feature of the proposed approach is its simplicity and relative efficiency, allowing a virtually unlimited number of new substances with different topologies with any properties that would make a significant contribution to the development of supramolecular chemistry and synthesis of new materials. Comparison of these experimental data and results of calculations of thermodynamic parameters and lattice energy of crystals can be used to establish the fundamental laws of existence of such structures. The volatility and solubility of the proposed compounds make them promising precursors to prepare composite inorganic and molecular films to study their catalytic, electromagnetic, optical, luminescent, sensory properties.
Figure 1. Pentanuclear heterocomplex [3Pd(aa)2*2Pb(hfa)2], sublimes at T=100oC and P=10-2 Torr.
