Inclusion compounds of a diol host with xylidines: controlled stoichiometries.
The diol host, 1,1'-bis-(4-hydroxyphenyl)cyclohexane (DHPC) and a number of xylidine isomers as guests formed a series of inclusion compounds that gave rise to various host:guest ratios controlled by crystallization temperatures. For the host DHPC with a particular xylidine isomer, the number of guests included generally decreases as the crystallization temperature increases. The crystal structures of these host-guest compounds were elucidated using single-crystal X-ray diffraction. Their thermal stabilities were characterized by TG and DSC analysis. The selectivity of enclathration by the host was measured by carrying out a series of competition experiments. The kinetics of guest decomposition were studied using isothermal and non-isothermal methods and reconciled with the crystal structures.
Structure–reactivity relations of inclusion compounds
The formation and stability of an inclusion compound depends on the process of molecular recognition between host and guest. Thermal analysis techniques are useful in measuring compound stability, while competition experiments may be employed to determine the selectivity of a particular guest from a mixture. Both stability and selectivity can be reconciled in terms of lattice energies. The kinetics of desorption, enclathration and guest exchange are discussed.
Unrolling the hydrogen bond properties of C–H···O interactions
It has long been known that C–H groups may form weak hydrogen 
bonds. The characteristics of these interactions, however, have been 
explored systematically only recently. Currently, a qualitative 
understanding is being replaced by quantitative insight into the general 
properties and functions of weak hydrogen bonds like 
C–H···O. The current state is reviewed here, 
with a focus on results obtained by crystal correlation studies.