Double-layer silicene-based carcerands: molecular containers for unstable compounds

Abstract

We have studied the formation of a “host-guest” type сarcerand with a double-layer silicene (DL-S) as a host and an unstable antiaromatic cyclobutadiene as a guest.

By employing the methods of MM+, РМ3 and Monte-Carlo, there has been studied the positioning of molecules of cyclobutadiene in a DL-S depending on intercalate concentration and intercalation temperature. At that the deformation vibrations of the DL-S crystal grate do not exceed 0.017 nm, and the vibrations of the intercalate molecules do not exceed 0.025 nm which provides for configuration and conformation stability of the system. The silicene planes do not move relatively each other and the order of the silicon atoms between the planes remains the same – AB… (similar to the silicene single crystal). When initially heated from 0 to ~273 K, the systems energy grows gradually, then rises sharply between 273–300 K and 350–400 K, then, with the temperature growth, it reaches a plateau which proves its high stability up to ~420 K.

In the temperature range 0–273 K there appears physical sorption while chemisorption is observed at higher temperature (~300 K) which is peculiar of π-π interactions of classical aromatic and quasiaromatic cyclic and heterocyclic systems.

There have been calculated the UV-spectra of the DL-S depending on the intercalate concentration in terms of the modified Benes-Hilderbrand method. There has been shown that the association constant of the system studied is 380 l·mol^–1, with computation accuracy ≥ 0.977.