Three-dimensional Chiral Framework Research Articles

Design and degradation of permanently porous vitamin C and zinc-based metal-organic framework

Bioapplication is an emerging field of metal-organic frameworks (MOF) utilization, but biocompatible MOFs with permanent porosity are still a rarity in the field. In addition, biocompatibility of MOF constituents is often overlooked when designing bioMOF systems, intended for drug delivery. Herein, we present the a Zn(II) bioMOF based on vitamin C as an independent ligand (bioNICS-1) forming a three-dimensional chiral framework with permanent microporosity. Comprehensive study of structure stability in biorelavant media in static and dynamic conditions demonstrates relatively high structure resistivity, retaining a high degree of its parent specific surface area. Robustness of the 3D framework enables a slow degradation process, resulting in controllable release of bioactive components, as confirmed by kinetic studies. BioNICS-1 can thus be considered as a suitable candidate for the design of a small drug molecule delivery system, which was demonstrated by successful loading and release of urea—a model drug for topical application—within and from the MOF pores.

From 1D zigzag chains to 3D chiral frameworks: synthesis and properties of praseodymium(iii) and neodymium(iii) coordination polymers

Reaction of H3TDA with PrIII/NdIII salts resulted in two coordination polymers, [Ln(H2O)4(HTDA)(H2TDA)]·H2O (Ln = Pr(1) and Nd(2), H3TDA = 1H-[1,2,3]-triazole-4,5-dicarboxylic acid), crystallizing in the monoclinic P21/c space group with a one-dimensional zigzag chain structure. The number of ligands and water molecules coordinated to the LnIII ions can be reduced by a hydrothermal method and the products transformed into {[Ln(TDA)(H2O)]·2.5H2O}n (Ln = Pr(3) and Nd(4)), crystallizing in the trigonal P3121 space group with a three-dimensional chiral framework structure. The compounds were characterized by elemental analysis, IR, PXRD, circular dichroism spectra and single crystal X-ray diffraction. The variable temperature magnetic susceptibility studies indicated that there are antiferromagnetic interactions between the LnIII ions in 1–4. Gas sorption and separation were studied as well.

Spontaneous resolution of novel Zn complexes in the formation of 3D metal–organic frameworks based on 2,2′-biimidazole ligand

The novel three-dimensional chiral framework of the four-coordinate zinc complexes, [Zn4(biim)3(ina)2] (1a and 1b) (H2biim=2,2′-biimidazole, ina=isoniconate), has been prepared via hydrothermal reaction. X-ray single crystal diffraction analysis shows the biim2− in title complexes acts as a tetradentate ligand and links four different Zn2+ ions. Spontaneous chiral resolution occurs in solvo-thermal reaction, which was confirmed by solid-state circular dichroism spectra. Photoluminescent spectra of compound 1 exhibit an intense blue emission at 440nm.

Role of Anions and Reaction Conditions in the Preparation of Uranium(VI), Neptunium(VI), and Plutonium(VI) Borates

U(VI), Np(VI), and Pu(VI) borates with the formula AnO(2)[B(8)O(11)(OH)(4)] (An = U, Np, Pu) have been prepared via the reactions of U(VI) nitrate, Np(VI) perchlorate, or Pu(IV) or Pu(VI) nitrate with molten boric acid. These compounds are all isotypic and consist of a linear actinyl(VI) cation, AnO(2)(2+), surrounded by BO(3) triangles and BO(4) tetrahedra to create an AnO(8) hexagonal bipyramidal environment. The actinyl bond lengths are consistent with actinide contraction across this series. The borate anions bridge between actinyl units to create sheets. Additional BO(3) triangles and BO(4) tetrahedra extend from the polyborate layers and connect these sheets together to form a three-dimensional chiral framework structure. UV-vis-NIR absorption and fluorescence spectroscopy confirms the hexavalent oxidation state in all three compounds. Bond-valence parameters are developed for Np(VI).

Assembly of Two Metal−Organic Frameworks with Intrinsic Chiral Topology from Achiral Materials

The assembly of Cu(CH3COO)2·H2O and pyridine-4,5-imidazoledicarboxylic acid (H3PyImDC) under solvothermal conditions in the presence of different organic templates yielded two three-dimensional chiral frameworks, |(C3H10N2)(C3H7NO)0.5(H2O)2|[CuIIC10H5O4N3] (1) and |(C4H9NO)0.5(H2O)8|[CuII2CuI(C10H5O4N3)2(C10H6O4N3)] (2). Both of the compounds crystallized in the cubic, P4332 space group and possessed open helical channels in the frameworks. To the best of our knowledge, compounds 1 and 2 present the first synthesized MOFs with a bmn and lcy-a net. Further characterization of the two compounds has been performed, including X-ray powder diffraction, inductively coupled plasma analysis, CHN, IR spectra, fluorescence spectra, X-ray photoelectron spectroscopy spectrum and thermogravimetric-differential thermal analysis.

Hydrothermal synthesis of a luminescent Europium(III) sulfate with three-dimensional chiral framework structure

The crystal structure and luminescent property of hydrothermally grown crystals of [NaEu(H 2O)(SO 4) 2] ( 1) are reported. The crystal structure is composed of three kinds of right-handed helical chains, {EuOSO 4}, {NaOSO 4} and {EuONa}, which are connected together to form a three-dimensional framework structure via corner-shared polyhedra. The sharp peaks in the emission spectrum of 1 are assigned and analyzed. Crystal data: Trigonal, P3 121, with a = 6.904 ( 1 ) Å , c = 12.799 ( 1 ) Å and z = 3 .

Syntheses, characterization and fluorescent properties of two square pyramidal Cu (II) inorganic–organic hybrid polymers

Two copper(II) carboxylate polymers of formula [Cu 2(OOCCH 3) 4(4,4′-bpy)]·DMF 1 and [Cu(OOCCH 2COO)(DMF)] 2 (DMF= N, N-dimethylformamide) have been synthesized in mixed DMF–CH 3OH–H 2O solution and characterized by X-ray diffraction, FT-IR, UV–vis, EPR, XPS and fluorescence. The structure of 1 consists of a two-dimensional supramolecular layer constructed by intermolecular π–π interactions of the bipyridine rings from adjacent one-dimensional [Cu 2(OOCCH 3) 4(4,4′-bpy)] chains. The space between the two neighboring layers is filled by the solvent DMF molecules and thus a sandwich-like supramolecular structure was formed. Polymer 2 contains a three-dimensional chiral framework constructed only by malonate ligand with syn– anti and anti– anti coordination modes. The fluorescent properties of 1 and 2 have been measured showing strong fluorescent emissions at room temperature.

Thermal Conversion of a Helical Coil into a Three-Dimensional Chiral Framework.

Thermal dehydration results in the solid-state supramolecular conversion of the helical coordination polymer [{[Cu(sala)](2)(H(2)O)}(n)] into the chiral three-dimensional covalent open network [{Cu(sala)}(n)] (shown schematically). X-ray crystallography reveals that hydrogen bonding plays a key role in this process. H(2)sala=N-(2-hydroxybenzyl)-L-alanine

Thermal Conversion of a Helical Coil into a Three-Dimensional Chiral Framework

Thermal dehydration results in the solid-state supramolecular conversion of the helical coordination polymer [{[Cu(sala)]2(H2O)}n] into the chiral three-dimensional covalent open network [{Cu(sala)}n] (shown schematically). X-ray crystallography reveals that hydrogen bonding plays a key role in this process. H2sala=N-(2-hydroxybenzyl)-L-alanine