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Recent studies show that the dynamic and reversible chemistry between carbon dioxide and primary amines can be used to build supramolecular polymers, class of polymers combining the conventional as well as the switchable properties of the conventional polymers. These gels are of great importance as they can be easily isolated, dried and stored refrigerated for several months and can even trap, store and release foreign molecules.

The thermodynamic and kinetic properties of tetraurea derivatived (2a,b) from the calix[4]arene with a rigidified cone conformation are reported. The dimeric capsules formed by 2a and 2b show increased thermodynamic and kinetic stabilities in comparison with the more flexible analogues tetraurea derivatives and differences in the selectivity of guest inclusion are noticed between both types of tetraurea calix[4]arenes.

An approach toward visual detection and chemical utilization of NO(sub 2)/N (sub 2)O(sub 4) is proposed, which employs simple calix[4] arenes. Chemical fixation of NO(sub 2)/N(sub 2)O(sub 4) was demonstrated through their quantitative transformation into the calixarene-NO (super +) complex and its use as a nitrosonium transfer agent in the synthesis of N-nitrosoamides.

Cavitands are synthetic structures with curved, open-ended cavities. Earlier cavitands were shallow, bowl-shaped structures. Access to deeper cavitands was prepared by bridging the resorcinarene hydroxyl groups with a preformed heterocycle. This was formed by condensation with a 6,7-disubstituted-2,3-dicholoroquinoxaline. An alternative method involves the use of a simpler building block in the bridging reaction and then extension of the rim through heterocyclic synthesis.

A method for synthesizing resorcinarene derivatives through dimerization is presented. These derivatives are characterized by self-complementary hydrogen-binding sites and extended sides. Large cavities are observed to form due to the occurrence of dimerization in solvents such as toluene-d8. The thermodynamic parameters for dimerization are believed to have resulted from self-inclusion and hydrogen bonding.

Calix(4)arene acts as a starting material in the preparation of calix(4)arene salenes, which is a bifunctional receptor for NaH2PO4. These receptors have anionic and cationic binding sites and form complexes simultaneously with anionic and cationic species. The bifunctional receptors are used to separate alkali metal phosphates.

A study of a new class of neutral receptors for anions revealed the structure to be organized as a H-bonded ribbon as a result of the formation of H-bonded dimers through H2PO4- anions, which were complexed by one uranyl cation. Three neutral receptors comprised of amide C(O)NH groups and an immobilized Lewis acidic binding site, (UO2(2+)).

Analysis of anion receptors based on chlorosulfonylated calix(4)arenes reveal that tetrakis(chlorosulfonyl)-calix(4)arenes may be proper precursors for the preparation of hydrophobic, neutral anion receptors. This is possible as complexes with anions result from sulfonamides obtained from tris(aminoethyl)amine.

Capped biscalix(4)arene-Zn-porphyrin (1) is a suitable receptor for various aza-heterocycles. Compound 1 is obtained by refluxing free base porphyrin with Zn(OAc)(sub 2)*2H2O in CHCl3-MeOH. The resulting compound contains a rigid cavity which effectively shields and provides hydrophobic binding to the incoming group. The 1H NMR spectra of 1 in CDCl3 reveals a typical singlet of porphyrin ring at 8.68 parts per million.

The structure and synthesis of neutral macrocyclic receptors that complex cations in apolar solvents with high selectivity depend on the organization of nucleophilic binding sites in complementary arrays. Neutral anion receptors containing immobile Lewis acidic uranyl cations are receptors of neutral molecules. Selective anion receptors are obtained by adding amido group substituents to salene moiety. Combining Lewis acidic uranyl centers and amide NH groups forms H-bonds with anion quests for selective anion recognition.

A separation strategy is described which combines selective solution complexation by macrocyclic receptors and C[O.sub.2]-induced molecular switching, leading to effective precipitation. Findings reveal that the architecture and complexation of properties of the separating materials are programmed through synthesis at the stage of their monomers.

The chemistry between CO2 and primary amines was used to construct novel types of supramolecular polymers and networks. Fluorescent self-assembling gel was prepared, which employs both hydrogen bonding and dynamic, thermally reversible carbamate bonds.

The entrapment and conversion of NO/N2O4 gases is proposed by the design of molecular nanotubes. The synthesis of nanotube's internal dimensions is presented and its reversible reactions with NO2/N2O4 in solution are studied.

A supramolecular approach for potential detection of SO2 is presented, which includes a noncovalent indicator-displacement assay and is based on the donor-acceptor chemistry between SO2 and amines. Although there are obvious UV changes upon addition of SO2 to an amine, incorporating the porphyrin in the assay brings the response into the visible region of the spectrum.

Research was conducted to examine a class of molecules that assemble in solution primarily by virtue of self-complementary shapes. The molecules allow the optimal expression of subtler forces such as van der Waals contacts and C-H/pi interactions. Their properties as dimeric species provide the first steps along the road to more complex assemblies based on the weakest of intermolecular interactions.

Research was conducted to examine the stereochemical relationships between encapsulated molecules that gave rise to an unusual form of isomerism that involves complexes-within-complexes. The mechanism consists of a molecular capsule results from the dimerization of tetraimide in apolar organic solvents. Results indicate that the control of guest orientations should cause enhanced interactions or even reactions inside the cylindrical capsules.

Flexible molecules are shown to be able to reversibly self-assemble to afford a well-defined receptor cavity. This phenomenon is modeled using the calix(4)arene structure, for which a unique dimeric binding mode for the encapsulation of small molecule guests has been developed. Three stable conformations were identified, namely, the cone, partial cone and 1,3-alternate. Results showed the conversion of the 96% partial cone to 100% cone by intermolecular forces. Up to 16 hydrogen bonds were formed in the self-assembled system.

Analytical studies of anion transport across supported liquid membranes indicate a preference for transport of H2PO(sub 4)(super -) over Cl- ion and this transport occurs either by an anion receptor or by a combination of cation and anion receptors. The ratio of fluxes divided by ratio of source phase anion concentrations of H2PO(sub 4)(super -) and Cl- is called selectivity. This selectivity depends on the nature of the anion receptor and is opposite to the dehydration energies of anions in the Hofmeister series.