Hydrogen-Bonded Helices in Crystals with Prescribed Organization

Abstract

Self-assembled molecular helices are ubiquitous in nature and can be found in many biologically important macromolecules. It is therefore not surprising that chemists have made significant efforts to introduce helicity in many artificial systems. [1] The inherent chirality present in such spiral structures is generally associated with enantioselectivity [2] or interesting optoelectronic properties. [3] Theoretical [4] and experimental [5] studies have indicated that helical supramolecular networks can affect chiral ordering in crystal lattices.Molecular helicity can be programmed by judicious selection of elements that are encoded with structural and conformational information designed to enforce intramolecular self-organization in a spiral arrangement. Examples such as helicenes, [6] poly(m-phenylene), [7] polyheterocyclic strands, [8] m-phenylacetylene oligomers, [9] b-peptides, [10] polyisocyanates, [11] and oligoarylamides [12] elegantly illustrate this concept. The generation of supramolecular helices requires an additional design element, namely, a reliable noncovalent motif that can provide the desired connectivity of the building blocks in a predictable manner. Hydrogen bonds, [13] metal coordination, [14] and p ± p stacking interactions [15] are often utilized in this regard. These design strategies, however, are generally limited to one dimension, coinciding with the helix direction, while the assembly and structure along the remaining two crystal dimensions are difficult to control. The rational construction of new materials with tailored functions and properties, however, requires control of crystal architecture in all three dimensions. Here we report the formation of hydrogen-bonded helices with predictable three-dimensional (3D) organization in the solid state. This study represents a key first step towards the rational design of crystalline, hydrogen-bonded chiral networks with potential applications in enantioselective separation. [16] We are actively involved in the design of molecular crystals based on the self-assembly of complementary guanidinium and organosulfonate ions, which typically crystallize in a quasihexagonal hydrogen-bonded network (Figure 1 a). [17] These 2D layers can be described as consisting of 1D ribbons along a 1 . The S ¥¥¥ S distance along this axis is nominally identical for all these compounds (7.5 AE 0.2 ä). The ribbons themselves aggregate by hydrogen bonding along the orthogonal direction b 1 . The magnitude of b 1 can vary significantly (7.3 ± 13 ä) as a result of puckering of the sheet about the hydrogen bonds that connect the ribbons. [24] CID was achieved by isolation of the ion of interest in the ion trap, then applying 0.1 ± 1.0 V AC resonance excitation at the secular frequency of the ion and allowing it to collide with helium gas.[25] M.

A New Di-Copper(II) Complex of Schiff-Base and 1,3-Di(pyridin-4-yl)propane Ligands: Synthesis, Spectral, Thermal Properties, and Crystal Structure

“…[20,21] Intermolecular hydrogen bonds and π stacking interaction is an important supramolecular force to govern the process of recognition and self-assembly. [9] In the crystal structure, a notable feature of 1 lies in the 1D network built through weak π -π stacking interactions between the phenyl rings of adjacent dimmer units ( Figure 2). The shortest interplanar perpendicular and ring-centroid distances of 3.481 (3) and 3.787 (4) Å have been observed.…”

“…[7,8] In particular, hydrogen bonded interactions play a key role in the guanidinium sulfonate and disulfonate compounds systematically studied by Custelcean and Ward. [9] Cai, [10] Côté, [11] and Shimizu [12] explored the coordination chemistry of the sulfonate group and the structural properties of metal arenesulfonates. Based on this background, many transition metal sulfonate complexes with novel 0-3D porous structures were obtained showing that the sulfonate group can directly coordination to the metal ion, [13][14][15][16][17] competing successfully with water molecules.…”

A New One-Dimensional Double Chains Cobalt Coordination Polymer With Taurine Schiff-Base and 4,4′-Bipyridine Ligands: Synthesis, Spectral, Thermal Properties, and Crystal Structure

“…[17][18][19][20] Significant progress has been made in understanding the supramolecular chemistry in extended solids with sulfonate groups built up by cooperative coordination and other weak intermolecular interactions. [21][22][23] In particular, hydrogen bonded interactions play a key role in the guanidinium sulfonate and disulfonate compounds systematically studied by Ward et al [24] To demonstrate the influence of the second ligand on the assembly of sulfonate ligands (H 2 Saes) and metal ions as well as the framework structures of their complexes, we show the syntheses and structure of a new cobalt(II) compound, {[Co(Saes)(H 2 O)(Bipy)]·H 2 O} n (1), which has been characterized by single-crystal X-ray diffraction and by studies of its thermal stability.…”

Highly Porous, Homochiral Metal–Organic Frameworks: Solvent‐Exchange‐Induced Single‐Crystal to Single‐Crystal Transformations

“…[2] Homochiral, porous MOFs are particularly attractive candidates as heterogeneous asymmetric catalysts for the economical production of optically active organic compounds due to the lack of chiral, inorganic zeolites. [3] Although we and others have recently provided preliminary evidence for the potential utility of homochiral, porous MOFs in enantioselective separation and catalysis, [4,5] several key issues remain to be addressed before practical applications of such materials can be realized. First, homochiral MOFs with permanent porosity are still extremely rare, even though there are now numerous reported examples of porous, achiral MOFs with extremely high surface areas.…”