Syntheses and characterization of copper(II) carboxylate dimers formed from enantiopure ligands containing a strong π···π stacking synthon: enantioselective single-crystal to single-crystal gas/solid-mediated transformations.

Tri- and tetrafunctional enantiopure ligands have been prepared from 1,8-naphthalic anhydride and the amino acids L-alanine, D-phenylglycine, and L-asparagine to produce (S)-2-(1,8-naphthalimido)propanoic acid (HL(ala)), (R)-2-(1,8-naphthalimido)-2-phenylacetic acid (HL(phg)), and (S)-4-amino-2-(1,8 naphthalimido)-4-oxobutanoic acid (HL(asn)), respectively. Reactions of L(ala)(-) with copper(II) acetate under a variety of solvent conditions has led to the formation and characterization by X-ray crystallography of three similar copper(II) paddlewheel complexes with different axial ligands, [Cu(2)(L(ala))(4)(THF)(2)] (1), [Cu(2)(L(ala))(4)(HL(ala))] (2), and [Cu(2)(L(ala))(4)(py)(THF)] (3). A similar reaction using THF and L(phg)(-) leads to the formation of [Cu(2)(L(phg))(4)(THF)(2)] (4).

Copper(II) carboxylate tetramers formed from an enantiopure ligand containing a π-stacking supramolecular synthon: single-crystal to single-crystal enantioselective ligand exchange.

An enantiopure ligand built from connecting the π···π stacking 1,8-naphthalimide supramolecular synthon with L-asparagine, L(asn)(-), forms tetrameric [Cu(4)(L(asn))(8)(py)(MeOH)]. The methanol ligand, located in a chiral pocket, is replaced enantioselectively when exposed to racemic ethyl lactate vapor to yield [Cu(4)(L(asn))(8)(py)((S)-ethyl lactate)], in a single-crystal to single-crystal gas/solid transformation.

Homochiral, helical supramolecular metal-organic frameworks organized by strong π · · · π stacking interactions: single-crystal to single-crystal transformations in closely packed solids.

Enantiopure, trifunctional carboxylate ligands synthesized by linking the strong π · · · π stacking 1,8-naphthalimide supramolecular synthon to three naturally occurring amino acids using the azide/alkyne click reaction have been prepared [amino acid = glycine (L(gly)(-)), alanine (L(ala)(-)), and serine (L(ser)(-))]. These ligands have been used to form complexes of the formula [M(L(amino acid))2(4,4'-bipy)(H2O)2] · xH2O (M = Fe, Co, Ni, Cu, Zn; x = 4.25-5.

Homochiral, helical metal-organic framework structures organized by strong, non-covalent pi-pi stacking interactions.

A new trifunctional ligand, L(ala), containing a carboxylate donor group, a homochiral center derived from L-alanine and a strong pi-pi stacking, 1,8-naphthalimide synthon, has been used to prepare the copper(II) complex [Cu(L(ala))2(4,4'-bipy)(H2O)2].4.25H2O that has a homochiral, helical, supramolecular metal-organic framework 3-D structure, organized in one dimension solely by strong non-covalent forces.