meta-Bridged calix[4]arenes with the methylene moiety possessing in/out stereochemistry of substituents

Calix[4]arenes possessing two different substituents on an additional methylene bridge were prepared and the relationship between the in/out positions of these substituents and the complexation properties was studied.

Hydrogen bond energies and cooperativity in substituted calix[n]arenes (n = 4, 5)

Hydrogen-bonded interactions in para-substituted calix[n]arenes (CX[n]) (n = 4, 5) and their thia analogues are analyzed using the recently proposed molecular tailoring approach. The cooperative contribution toward the hydrogen-bonding network within the CX[5] host is shown to be nearly 5 times larger than that in its thia analogue. Hydrogen bond strengths in the O-H···O network are enhanced on substitution of an electron-donating group. The cooperativity contributions are reflected in the electron density at the bond critical point in the quantum theory of atoms in molecules.