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These new theoretical approaches have a great potential to aid in molecular engineering of smart materials for various technological applications.

The research in my group involves combining experimental and theoretical approaches to rational design of novel nanostructured materials with potential practical applications as optoelectronic and molecular recognition devices, as well as shape- and size-selective catalysts, adsorbents and sensors.

• Fundamental ab initio and experimental description of solid host/molecular guest interactions

Nanoporous zeolites and molecular sieves have found numerous uses in adsorption, catalytic, and ion-exchange processes, and more recently, as chemical sensors and microelectronic quantum dot devices. The development of new nanoporous hosts for these applications requires fundamental understanding of interactions between guest molecules and the pore structure in these materials. These interactions can be investigated by a number of theoretical and experimental methods.

The current theoretical approaches based on classical mechanical forcefields are attractive because of their simplicity and computational efficiency when handling interactions of even hundreds of atoms. However, the current interatomic potentials suffer from the poor transferability arising from the lack of consistent forcefield parameters and approximate energy expressions, which inadequately represent the fundamental intermolecular interactions. Some important dynamic characteristics of zeolites, such as the non-framework cation motion, are not accounted for either.

This project is aimed at deriving consistent forcefield parameters by density functional theory (DFT) quantum mechanical calculations. The computational ab initio activity is assisted by the experimental studies of well-defined host-guest systems, e.g. the measurements of adsorption-induced shifts of the N₂ and O₂ stretching modes in vibrational spectra.

The classical interatomic potentials are developed which include realistic two- and three-body dispersion, induction, repulsion, and permanent charge interaction terms. Finally, the charge-balancing non-framework cations in zeolites are relaxed to allow their "motion" during Grand Canonical Monte Carlo simulation of adsorption.

Validated interatomic potentials are used to predict molecular guest/solid host interactions for the exploratory part of the program described below.

• Directed self-assembly of novel open tetrahedral frameworks

Various cage structures, such as cubes, hexagonal prisms, and cancrinite cages, occur as building blocks in many open tetrahedral frameworks. Some isolated cage building blocks, such as cubes, have been observed in situ under synthesis conditions, and some thought that the nucleation and growth of open tetrahedral frameworks occurs via pre-organization and condensation of these units. However, there are no reports of successful synthesis of open tetrahedral frameworks by direct self-assembly of such building blocks.

This exploratory synthesis project is aimed at using nanocluster building blocks for structure-directed self-assembly into extended open frameworks and includes:

1. Solution phase synthesis of open tetrahedral structures from isolated cage anions;
2. Crystallization of open tetrahedral frameworks from nanophase nucleation agents;
3. Structure-directed self-assembly of supertetrahedral building blocks.

Molecular modeling is applied to generate new framework topologies, built from nanocluster building blocks. Computational de novo design methodology is then used to select organic structure-directing molecules for target structure synthesis on the basis of the shape- and charge-matching between the organic guest molecule and the nanopore structure of a host. The novel structures obtained are characterized with respect to potential practical applications in catalysis, ion-exchange, separations, opto- and microelectronics, and chemical sensing.

• Nanoscale organization of vanadyl(IV) phosphates for catalytic oxidation of hydrocarbons

The "bulk" vanadyl(IV) pyrophosphate, (VO)₂P₂O₇ is widely used as the catalyst for n-butane oxidation to maleic anhydride, the only example of an industrial selective oxidation of an alkane. Although the very mechanism of this reaction and the nature of the active sites are still unknown, the researchers agree that crystalline (VO)₂P₂O₇ serves as a support which stabilizes some specific surface structure responsible for selective oxidation of n-butane.

Decreasing the dimensions of the crystalline active phase below 100 nm scale emerges as one of the main approaches to increase the active surface area and the catalytic performance of (VO)₂P₂O₇ in n-butane oxidation. The current work is aimed at creating vanadyl(IV) phosphate nanophases, which preserve the local structure of (VO) 2P2O7, and three experimental approaches are pursued:

1. Synthesis of supported nanocrystalline vanadyl(IV) phosphates.
2. Synthesis of mesoporous vanadyl(IV) phosphates.
3. Self-assembly of monolayer vanadyl(IV) phosphates on metal oxide surfaces.

The nanophase vanadyl(IV) phosphates obtained are used to establish fundamental structure-reactivity relationships in selective oxidation of lower hydrocarbons, such as ethane, propane, and n-butane.