OP-II-3

PP-I-21SIMULATION OF DIRECTIONAL INTERMOLECULARINTERACTIONS IN ORGANIC MONOLAYERS:TRIMESIC ACID ON SINGLE CRYSTAL (111) SURFACEFefelov V.F. 1 , Gorbunov V.A. 1 , Myshlyavtsev A.V. 1,2 , Myshlyavtseva M.D. 11 Omsk state technical university, Omsk, Russia2 Institute of hydrocarbon processing SB RAS, Omsk, RussiaE-mail: Vitaly_Gorbunov@mail.ruThe production of self-assembled molecular films and supramolecularnanostructures of organic molecules on metalic surfaces is now the constantlygrowing field of researching [1,2]. The most of investigations are focussed on effortsto construct different organic-inorganic heterostructures with tailored properties suchas reactivity, ultra-fast optical response and chemical sensing. Understanding theforces governing the arrangement of organic molecules is the key to controle andcreation of self-assembled organic structures. A promising class of candidates toform supramolecular aggregates are moleculas with functional groups for hydrogenbond formation [1-3]. Hydrogen bonding can be used to tune the spatial arrangementof functionalized molecules on surfaces. The choice of molecular shape and size andespecially the arrangement of hydrogen-bonding are crucial to the correctassembling of tailored supramolecular arrays [1-3].The TMA molecule is carboxylic acid with threefold symmetry, comprised of aphenyl ring and three identical carboxyl end-groups in the same plane. TMAmolecules at surface can form two stable hydrogen bonded structures at least [1,2,4](Fig. 1b). The first structure unit is composed of sixfold rings of TMA with perfectarrangement of the hydrogen bonds in which each molecule is part of threeneighbouring rings. Nextly, when we add molecules onto the surface, each sixfoldring accepts single TMA guest molecules in different positions until the saturatedmonolayer is reached – second stable hydrogen bonded structure.In this study we propose the lattice gas model of self-assembled monolayer ofTMA molecules on (111) surface. In the framework of the simplest model weconsider that TMA molecule occupies only one site of two-dimensional triangularlattice. Each site of the lattice has its own occupation variable which equels to zerowhen site is empty; and 1 or 2 if the site occupied by TMA molecule with first orsecond plannar orientation, respectivly (see Fig. 1a). It is worth noting that thesimplest case of our model is similar to the well-studied Blume – Capel model but our258