Francesco Troisi

Absolute configuration assignment of inherently chiral calix[4]arenes using DFT calculations of chiroptical properties.

The racemate of an inherently chiral meta-substituted calix[4]arene derivative 3 has been resolved via enantioselective HPLC. Measured optical rotation dispersion and electronic circular dichroism have been compared with DFT theoretical predictions. The comparison indicates that the absolute configuration of the dextrorotatory enantiomer (+)-3 is cS. The procedure has been successfully tested against a literature precedent confirming the validity of the method.

Conformationally locked calixarene-based histone deacetylase inhibitors.

Alkyl- and arylamidocalix[4]arene derivatives 1-11 have been designed and theoretically evaluated by docking studies as potential histone deacetylase inhibitors (HDACi). On the basis of the trimodal distribution of the calculated inhibition constants (K(i)), five alkyl- or arylamido derivatives (3, 7, 8, 9, and 11) were synthesized and tested. A qualitative accordance between the experimental results and the theoretical predictions was obtained, confirming that appropriately substituted arylamidocalix[4]arenes are active HDACi.

A solid-state molecular capsule based on p-sulfonatocalix[7]arene and dicationic Diquat guest

An extended framework of molecular capsules based on p-sulfonatocalix[7]arene and a dicationic Diquat guest has been obtained. One Diquat guest molecule is encapsulated inside two trimeric ¾-cone subunits of two different p-sulfonatocalix[7]arene caps. The molecular capsules are sealed electrostatically by means of interactions between anionic sulfonato groups and Ba2+ cations. Interestingly, the extended capsular framework gives rise to cavities hosting water molecules.

Oxyfunctionalization of calixarene quinone rings.

The epoxidation of quinone rings of calixquinones represents a valid route for the introduction of oxygenated functionalities into the de-tert-butylated calixarene walls originating cis-diepoxy-p-dione moieties. Carbonyl reduction of these systems leads to hybrid calixarenes containing dianhydroinositol moieties (calixinositols) belonging to the calixcyclitols family. The regio- and stereochemistry of these derivatives was determined by 2D NMR studies, in conjunction with MM3 calculations and X-ray crystallography.

Solid-state assembly of oxyfunctionalized calix[4]arene derivatives

The solid-state assembly of four calix[4]arene derivatives bearing one or two rings oxyfunctionalized with epoxy and hydroxyl functional groups has been structurally studied by X-ray crystallography. In three cases the presence of OH groups pointing towards the exterior of the molecule allows the formation of intermolecular OH⋯epoxy H-bonds, which give rise to columnar structures, with zigzag or parallel oriented molecules, or helical arrangement of quadruplex elements. In one instance, in the absence of intermolecular H-bonds, columnar stacks of molecules are obtained mainly through intermolecular van der Waals interactions.

Solid-state assembly of calixcyclitol derivatives

The solid-state assembly of two calixcyclitol derivatives bearing two or one rings (compounds 1 or 2, respectively) oxyfunctionalized with oxetane and hydroxyl functional groups has been structurally studied by X-ray crystallography. Calixcyclitol 1 can assemble to give a H-bonded layered (crystals 1A) or double-columnar (crystals 1B) structure with alternating polar and lipophilic zones. Calixcyclitol 2 gives a double-helical arrangement through the intermediacy of H2O and MeOH molecules.