Solid calixarenes as receptors are characterised by phase transitions, which occur in binding of neutral molecules of guest compounds with the formation of clathrates or guest -- host intercalation compounds. The process of clathrate formation in the binding of a guest by a host is accompanied by a significant rearrangement of the packing of host molecules, and the result of this rearrangement can depend considerably on the molecular structure of the guest. This book presents and discusses research on the subject of solid-state complexation.