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Accueil > Séminaires > 2017

Theoretical aspects in realization of functional nanoporous materials

Rodion Belosludov, Tohoku University (Sendai, Japon)

Salle de séminaire IRSAMC, Jeudi 16 Mars, 14h - 15h

The fundamental strategy to realize specific or highly selective adsorption process is based on the understanding of the chemical and physical properties of the adsorbed molecules and the design and synthesis of nanoporous compounds that can recognize the differences between the various gases. This requires precise control of the structure and detailed understanding of the structure-property relationships.

Moreover, materials used for innovative storage, separation and drug delivery technologies must exhibit long-term stability, possess specific targeting and/or recognition ability and not pose environmental hazards or health effects. From these points of view, soft nanoporous materials can be considered as prospective functional adsorbents or/and delivery systems with regular nano-sized spaces and unique recognition ability [1].

Formalism for calculating the thermodynamic properties of a soft nanoporous materials with weak guest-host interactions was realized [2]. The proposed model accounted for multiple cage occupancy, host lattice relaxation, and the description of the quantum nature of guest behavior. Using this approach, the phase diagrams of various clathrate hydrates was constructed and they are in agreement with available experimental data [2-4]. In order to evaluate the parameters of weak interactions, a time-dependent density-functional formalism and local density technique entirely in real space have been implemented for calculations of vdW dispersion coefficients for atoms within the all-electron mixed-basis approach. The combination of both methods enables one to calculate thermodynamic properties of soft nanoporous materials without resorting to any empirical parameter fittings.

We have also shown in collaboration with experimentalists that the concept using a designable regular MOF material could be applicable to a highly stable, selective adsorption system [5-7]. Thus, the high sorption ability of a specific metal-organic framework (MOF) for acetylene from a CO2/C2H2 gas mixture is demonstrated [5]. The high selectivity of CO has been achieved from a mixture with nitrogen by both the local interaction between CO and accessible Cu2+ metal sites and the modification of nanopore size [6]. The synthesis of MOF with the urotropine moiety can significantly improve the selective adsorption of C2H2 and CO2 gases [7].

Recently, we have presented a design for functional 3D porphyrin-based nanostructures, which would bridge the gap between the well-known fullerenes and nanotubes and a new class of the functional nanomaterials. It was shown that the electronic structures and optical properties of studied structures could be easily tuned via their size, topology, and the presence of bridging sp3 carbon atoms. The optical properties of the new materials can rival those of known quantum dots. The ability to store large quantities of methane (106–216 cm3 (STP)/cm3) was observed in all cases with several compounds being close to or exceeding the DOE target of 180 cm3 (STP)/cm3 [8].

[1] S. Horike et al., Nature Chem. 1 (2009) 695.
[2] R. V. Belosludov et al. J. Chem. Phys. 131 (2009) 244510.
[3] R. V. Belosludov et al. J. Phys. Chem. C 118 (2014) 2587.
[4] R. V. Belosludov et al. J. Renew. Sust. Energy, 6 (2014), 053132.
[5] R. Matsuda et al. Nature 436 238 (2005).
[6] H. Sato et al. Science 343 (2014) 167.
[7] A. Sapchenko et al., Chem. Comm. 51 (2015) 13918.
[8] R. V. Belosludov et al. Phys. Chem. Chem. Phys. 18 (2016) 13503.