Two Zinc Architectures: A Mononuclear Complex and a 2D Wave-like Organic-inorganic Hybrid Layer

Self-assembly of Zn(NO3)2·6H2O and 2,3,5,6-tetrabromoterephthalic acid(H2TBTA) gave rise to two new zinc metal-organic frameworks,Zn(HTBTA)2(phen)2·H2O(1) and Zn(TBTA)1/2(μ2-OH)(H2O)·0.25EtOH(2).Complex 1 is a mononuclear molecule.The hydrogen bonding interactions further connect the mononuclear molecules to generate a 2D supramolecular architecture.Complex 2 is a 2D organic-inorganic hybrid layer framework constructed from 1D rod-shaped secondary building units.     

Thermoanalytical Study of O,O'-Dibenzoyl-(2R,3R)-Tartaric Acid Supramolecular Compounds Part II. Investigation of the resolution of racemic alcohols

The resolution of three chiral alcohols with O,O'-dibenzoyl-(2R,3R)-tartaric acid (DBTA) via diastereoisomeric supramolecular compound formation was investigated with thermoanalytical methods. On the basis of TG measurements the DBTA:chiral alcohol molar ratio in the compounds is 1:1 which agrees with the results of single-crystal X-ray diffraction analysis. The DBTA – chiral alcohol supramolecular compounds have different supramolecular structure than the DBTA – achiral alcohol supramolecular compounds. The supramolecular compounds containing cyclohexanols have higher thermal stability than the compounds containing acyclic aliphatic alcohols. The amount of unreacted DBTA monohydrate in the solid phase can be determined both with DSC and with TG measurements. This revised version was published online in August 2006 with corrections to the Cover Date.     

Supramolecular aggregation of block copolymers in the solid state as assisted by the selective formation of inclusion crystals

Supramolecular self-assembly of a host molecule with selected blocks of triblock copolymers enabled the formation of inclusion 2D nanocrystals that connect consecutive copolymer chains. Indeed, the selective inclusion of ethylene oxide (EO) blocks in inclusion crystals and the phase segregation of PO blocks of poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (EO(n)PO(m)EO(n)) triblock copolymers provide an efficient route to create alternated crystalline lamellae and amorphous layers, forming a well-organized material. The spontaneous formation of the supramolecular architectures was realized by a solvent-free mechanochemical approach or by thermal treatment of the copolymer and host (tris-o-phenylenedioxycyclotriphosphazene), as demonstrated by in situ synchrotron X-ray diffraction. The driving force for the fabrication of crystalline inclusion compounds with selected EO segments is based on the establishment of cooperative noncovalent intermolecular interactions, while steric effects prevent the formation of the inclusion crystal with the remaining PO blocks. The 2D (1)H-(13)C solid state and fast-(1)H MAS NMR provide direct evidence of the intimate interactions between the host and EO block and the topology of the block copolymer in the material. The large magnetic susceptibility generated by the aromatic host nanochannels surrounding the included EO chains was interpreted by ab initio calculations (HF-GIAO/DGDZVP) that carefully reproduce the chemical shifts associated with the effects of guest-host interactions. The theoretical calculations enable the measurement of short intermolecular distances between the host and the target block, demonstrating the existence of a diffuse network of multiple CH···π host-guest interactions that improve the robustness of the supramolecular architecture. The overall evidence enforces the strategy of combining the use of block copolymers and clathrate-forming molecules to fabricate organized materials through noncovalent interactions.     

Chiroptical nanofibers generated from achiral metallophthalocyanines induced by diamine homochirality

Optically active cofacial π-π phthalocyanine (Pc) stacked supramolecules were spontaneously and successfully generated from a mixture of four possible geometric isomers (C(4h), D(2h), C(2v), C(s)) of achiral 4(5),4'(5'),4'(5'),4'(5')-tetracarboxymetallophthalocyanine (tcPcM; M=Ni, Cu) induced by an equimolar amount of inexpensive chiral diamine molecular sources in DMSO/CHCl(3) mixed solvent under optimized conditions of the volume ratio of poor/good cosolvents, the molar ratio of chiral molecular diamine to tcPcM, the cavity metal of phthalocyanine, and the addition order of the amines. The sign and amplitude of circular dichroism spectra due to the supramolecular chirality and structure of the diamine molecules are impossible to remove by additions of the antipode diamine and trifluoroacetic acid. The chiral diamine was partly contained in nanofibers, and that retained in the solution can be recycled and reused to induce optically active tcPcM supramolecules.     

Control of release properties of guest molecules by the type of benzoheterocyclic ring in supramolecular host complexes

Three types of supramolecular benzoheterocyclic host complexes were successfully prepared using (1R,2S)-2-amino-1,2-diphenylethanol and three types of benzoheterocyclic (benzothiophene, benzofuran, and benzopyrrole) acid derivatives. The host complexes had one-dimensional (1D) channel-like cavities that were formed by the assembly of two-component 2₁-helical columnar network structures, which included guest alcohol molecules. The release behavior of the guest molecules could be tuned by the type of heterocyclic ring in the supramolecular host complex.     

Supramolecular chirality in crystalline assemblies of bile acids and their derivatives; three-axial, tilt, helical, and bundle chirality

Steroidal bile acids and their derivatives exhibit characteristic inclusion behaviors in the crystalline state. Their crystals present varied assemblies due to asymmetric molecular structures, which relate to supramolecular properties through cooperative weak interactions. An overview indicates that the steroidal assemblies lie in an intermediate position among various molecules and have hierarchical structures such as primary, secondary, tertiary, and host-guest assemblies like proteins. Such an interpretation brought about the idea that the assemblies with dimensionality present supramolecular chirality such as three-axial, tilt, helical, bundle, and complementary chirality. This concept of the supramolecular chirality enables us to understand formation of chiral crystals starting from the molecular chirality of the steroidal molecules.     

Effect of intermolecular dipole-dipole interactions on interfacial supramolecular structures of C3-symmetric hexa-peri-hexabenzocoronene derivatives

Two-dimensional (2D) supramolecular assemblies of a series of novel C(3)-symmetric hexa-peri-hexabenzocoronene (HBC) derivatives bearing different substituents adsorbed on highly oriented pyrolytic graphite were studied by using scanning tunneling microscopy at a solid-liquid interface. It was found that the intermolecular dipole-dipole interactions play a critical role in controlling the interfacial supramolecular assembly of these C(3)-symmetric HBC derivatives at the solid-liquid interface. The HBC molecule bearing three -CF(3) groups could form 2D honeycomb structures because of antiparallel dipole-dipole interactions, whereas HBC molecules bearing three -CN or -NO(2) groups could form hexagonal superstructures because of a special trimeric arrangement induced by dipole-dipole interactions and weak hydrogen bonding interactions ([C-H···NC-] or [C-H···O(2)N-]). Molecular mechanics and dynamics simulations were performed to reveal the physics behind the 2D structures as well as detailed functional group interactions. This work provides an example of how intermolecular dipole-dipole interactions could enable fine control over the self-assembly of disklike π-conjugated molecules.     

A series of chiral coordination polymers containing helicals assembled from a new chiral (R)-2-(4'-(4'-carboxybenzyloxy)phenoxy)propanoic acid: syntheses, structures and photoluminescent properties

Ten new chiral coordination polymers, namely, [Ni(L)(H(2)O)(2)] (1), [Co(L)(H(2)O)(2)] (2), [Cd(L)(H(2)O)] (3), [Cd(L)(phen)] (4), [Mn(2)(L)(2) (phen)(2)]·H(2)O (5), [Cd(2)(L)(2)(biim-4)(2)] (6), [Zn(2)(L)(2)(biim-4)(2)] (7), [Cd(L)(pbib)] (8), [Cd(L)(bbtz)] (9) and [Cd(L)(biim-6)] (10), where phen = 1,10-phenathroline, biim-4 = 1,1'-(1,4-butanediyl)bis(imidazole), pbib = 1,4-bis(imidazole-1-ylmethyl)benzene, bbtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, biim-6 = 1,1'-(1,6-hexanedidyl)bis(imidazole), and H(2)L = (R)-2-(4'-(4'-carboxybenzyloxy)phenoxy)propanoic acid, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), powder X-ray diffraction (PXRD), elemental analyses and thermogravimetric (TG) analyses. Compounds 1 and 2 exhibit similar 1D left-handed helical chains, which are further extended into 3D supramolecular structures through O-H···O hydrogen-bonding interactions, respectively. Compound 3 shows a 2D double-layer architecture containing helical chains. Compound 4 features two types of 2D undulated sheets with helical chains, which are stacked in an ABAB fashion along the c direction. Compound 5 possesses a 1D double chain ribbon structure containing unusual meso-helical chains, which is linked by π-π interactions into a 2D supramolecular layer. These layers are further extended by hydrogen-bonding interactions to form a 3D supramolecular assembly. Compounds 6 and 7 are isostructural and exhibit 2D (4(4))-sql networks with helical chains. Neighboring sheets are further linked by C-H···O hydrogen-bonding interactions to generate 3D supramolecular architectures. Compounds 8-10 are isostructural and display 3D 3-fold interpenetrating diamond frameworks with helical chains. The effects of coordination modes of L anions, metal ions and N-donor ligands on the structures of the coordination polymers have been discussed. The luminescent properties of 3, 4 and 6-10 have also been investigated in detail.     

Supramolecular [60]Fullerene Liquid Crystals Formed By Self‐Organized Two‐Dimensional Crystals

Fullerene‐based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self‐organization and external‐field‐responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self‐organization driven by π–π interactions to form triple‐layer two‐dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals.     

Synthesis and structural chemistry of alkali metal tris(HMDS) magnesiates containing chiral diamine donor ligands

Six alkali metal tris(HMDS) magnesiate complexes (HMDS, 1,1,1,3,3,3,-hexamethyldisilazide) containing chiral diamine ligands have been prepared and characterised in both the solid- and solution-state. Four of the complexes have a solvent-separated ion pair composition of the form [{M·(chiral diamine)(2)}(+){Mg(HMDS)(3)}(-)] [M = Li for 1 and 3, Na for 2 and 4; chiral diamine = (-)-sparteine for 1 and 2, (R,R)-TMCDA for 3 and 4, (where (R,R)-TMCDA is N,N,N',N'-(1R,2R)-tetramethylcyclohexane-1,2-diamine)] and two have a contacted ion pair composition of the form [{K·chiral diamine}(+){Mg(HMDS)(3)}(-)](n) [chiral diamine = (-)-sparteine for 5 and (R,R)-TMCDA for 6]. In the solid-state, complexes 1-4 are essentially isostructural, with the lithium or sodium cation sequestered by the respective chiral diamine and the previously reported anion consisting of three HMDS ligands coordinated to a magnesium centre. As such, complexes 1-4 are the first structurally characterised complexes in which the alkali metal is sequestered by two molecules of either of the chiral diamines (-)-sparteine (1 and 2) or (R,R)-TMCDA (3 and 4). In addition, complex 4 is a rare (R,R)-TMCDA adduct of sodium. In the solid state, complexes 5 and 6 exist as polymeric arrays of dimeric [{K·chiral diamine}(+){Mg(HMDS)(3)}(-)](2) subunits, with 5 adopting a two-dimensional net arrangement and 6 a linear arrangement. As such, complexes 5 and 6 appear to be the only structurally characterised complexes in which the chiral diamines (-)-sparteine (5) or (R,R)-TMCDA (6) have been incorporated within a polymeric framework. In addition, prior to this work, no (-)-sparteine or (R,R)-TMCDA adducts of potassium had been reported.     

meta-Substituted benzamide oligomers that complex mono-, di- and tricarboxylates: folding-induced selectivity and chirality

meta-Substituted arylamide trimer, pentamer and heptamer have been prepared from simple benzene-1,3-diamine, benzene-1,3-dicarboxylic acid, and 3-aminobenzoic acid units. 2D NOESY (1)H NMR experiments reveal that these flexible oligomers form folded conformations to complex di- and tricarboxylate anions of varying sizes and shapes in DMSO of high polarity, which is driven by multiple intermolecular N-H···O=C and C-H···O=C hydrogen-bonds between the amide and aromatic hydrogens of the oligomers and the carboxylate oxygens of the anions. Generally, tricarboxylate anions display an increased binding affinity compared with the dicarboxylate anions and the complexes formed by 1,3-benzenedicarboxylate anion are more stable than those formed by 1,2- or 1,4-benzenedicarboxylate anions. Circular dichroism experiments show that chiral glutamic acid dianion can induce the oligomers to produce chiral bias, leading to the formation of chiral supramolecular complexes.     

Gas-chromatographic separation of enantiomers of 2-chlorobutane and 2-bromobutane on a cyanuric acid-modified Carboblack C adsorbent

The enantiomers of 2-chlorobutane and 2-bromobutane were separated by gas chromatography on a Carboblack C adsorbent modified by 10% cyanuric acid. Upon thorough mechanical stirring of a solution, cyanuric acid was shown to form chiral supramolecular structures on the surface of adsorbent particles analogously to the Kondepudi formation of chiral crystals of achiral molecules. The enantiomers of 2-bromobutane and 2-chlorobutane were found to undergo, respectively, complete and partial separation on the cyanuric acid-modified Carboblack C adsorbent. The separation of enantiomers is due to a high enantioselectivity of the modified adsorbent. The analysis of thermodynamic functions of adsorption showed that the differences in specific retention volumes of enantiomers are caused by the fact that one of enantiomers is adsorbed predominantly within the cavity of the supramolecular structure of cyanuric acid and another one is adsorbed on its surface. Separation on the proposed chiral stationary phase is characterized by the relative standard deviation of retention volumes no more than 7%.     

One-Step Synthesis of Cyclophanes as Crystalline Sponge and Their [2]Catenanes through SNAr Reactions

This work reports that cyclophanes and their [2]catenanes were synthesized by the S_NAr reactions of disubstituted adamantanes bearing halophenol units and 3,6-dichlorotetrazine in moderate yields. In the crystalline state, the cyclophanes had hexagonal structures with a cavity. The [2]catenanes were composed of two macrocycles that were singly interlocked and orthogonally arranged, indicating the construction from eight component molecules through eight C−O bonds in a one-step reaction in up to 33 % yield. The cyclophanes were assembled to afford a supramolecular organic framework in the solid state, which exhibited permanent intrinsic porosity and adsorption of leaf alcohol or aldehyde in a single-crystal to single-crystal fashion. The molecular structures of the liquid guests were determined by single-crystal X-ray analysis. The formation of catenanes and the use of cyclophane-based porous crystals in the crystalline sponge method may be largely ascribed to the solvophobic effects and the van der Waals interactions that originate in the aliphatic and bulky nature of the adamantane units.     

Supramolecular Tilt Chirality Derived from Symmetrical Benzene Molecules: Handedness of the 21 Helical Assembly

Achiral molecules can form aggregates with chirality. This depends on the relative position of the molecules, in other words, the tilt of the molecules (so‐called supramolecular tilt chirality). In this paper, we describe supramolecular chirality appearing in a 2₁ column composed of symmetrical benzene molecules, which is formed in the host cavity of inclusion crystals of cholic acid. Moreover, we determined the handedness, that is, right or left, of the 2₁ helical column of benzene on the basis of the molecular tilt. Determination of the 2₁ helical handedness was performed on assemblies of other benzene derivatives in cholic acid crystals and benzene assemblies in other host frameworks selected from the Cambridge Structural Database. Finally, we demonstrated complementarity of the handedness between the 2₁ symmetrical host framework of cholic acid and the benzene column.     

Assembly and properties of transition-metal coordination polymers based on semi-rigid bis-pyridyl-bis-amide ligand: effect of polycarboxylates on the dimensionality

Seven new coordination polymers, [Co()(1,3-BDC)(H(2)O)(3)]·H(2)O (), [Co()(1,2-BDC)(H(2)O)]·H(2)O (), [Co(3)()(1,2,4-BTC)(2)(H(2)O)(4)]·4H(2)O (), [Co()(NPH)]·2H(2)O (), [Cu()(1,3-BDC)] (), [Cu()(1,2-BDC)] (), [Cu()(1,3,5-HBTC)(H(2)O)](2)·2H(2)O () ( = N,N'-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide, 1,3-H(2)BDC = 1,3-benzenedicarboxylic acid, 1,2-H(2)BDC = 1,2-benzenedicarboxylic acid, 1,2,4-H(3)BTC = 1,2,4-benzenetricarboxylic acid, H(2)NPH = 3-nitrophthalic acid and 1,3,5-H(3)BTC = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized by assembling transition-metal cobalt-copper salts with semi-rigid bis-pyridyl-bis-amide ligand and different aromatic polycarboxylic acids. Complex exhibits a one-dimensional (1D) sinusoidal-like chain, which is further assembled into a three-dimensional (3D) supramolecular framework through hydrogen-bonding interactions. Complex possesses a 3D framework with 4-connected 6(6) topology, which contains a two-dimensional (2D) distorted asymmetric hexagonal grid. When 1,2,4-BTC is used in complex , a 3D framework with (6(3)·8(2)·10)(2)(6(5)·8)(2)(8) topology is constructed. Complex possesses a 3D framework with 4-connected 6(6) topology, which is similar to that of except for containing a 2D symmetric hexagonal grid. When Co(II) ion is replaced by Cu(II) ion, the 3D framework of complex with (4·6(2))(4·6(6)·8(3)) topology based on and 1,3-BDC ligands is obtained. Complex shows a 2D cross network consisting of a superposed Cu- 1D chain and 1,2-BDC, which is further expanded into a 3D supramolecular framework by hydrogen-bonding interactions. In complex , 1,3,5-HBTC is employed as the auxiliary ligand, and a 3D supramolecular framework based on the undulated 2D layers is formed through π-π stacking and hydrogen-bonding interactions. Both the metal ions and polycarboxylates play important roles in the construction of the title complexes. In addition, the electrochemical behaviors and the fluorescence properties of the seven complexes have been investigated.     

Enantioseparation of 1-arylethanols via a supramolecular chiral host consisting of N-(2-naphthoyl)-L-aspartic acid and an achiral diamine

A supramolecular chiral host consisting of N-(2-naphthoyl)-L-aspartic acid (L-1) and meso-1,2-diphenylethylenediamine (2) is effective in enantioseparation of 1-arylethanols (up to 96% ee with 100% inclusion ratio). Here we report three different methods to prepare the inclusion crystals and discuss the chiral recognition mechanism on the basis of X-ray crystallography results.     

The effect of the shape of a mesogenic group on the structure of supramolecular aggregates based on wedge-shaped and cone-shaped dendrons

This review addresses the key principles underlying the formation of liquid crystalline phases based on wedge-shaped and cone-shaped dendrons of different chemical nature. Despite rich phase diversity of the above systems, the development of a mesophase can be reliably predicted by the geometric model, which compares the shape of a wedge dendron with the radial density distribution in the relevant Voronoi polyhedra. 2D columnar phases formed by chiral [7]-heterohelicene molecules with long aliphatic side chains are described in detail. The as-formed columnar aggregates are shown to possess a helical 13₂ symmetry and are composed of thirteen blocks, and each block involves six molecules. In this case, the internal structure of the first-level (lower) supramolecular aggregate appears to be different from that of the helical supramolecular structure.     

Chiral recognition of N-thiophosphorylated thioureas via nickel(ii) coordination assisted by 4-dimethylaminopyridine

Nickel(ii) complexes were synthesized using chiral N-thiophosphorylated thioureas as the starting compounds and 4-dimethylaminopyridine as a co-ligand. The reaction with racemic thiourea afforded homochiral complexes due to the distortion of the nickel coordination. The unsaturated coordination sphere of nickel ions results in the formation of supramolecular homochiral 1D chains in the crystal through steric key—lock interactions between adjacent molecules. Conformational flexibility of the ligands is responsible for disorder of molecules in the crystals and the occurrence of polymorphs.

     

Efficient optical resolution of secondary alkyl alcohols by chiral supramolecular hosts

A novel tunable multi-chiral supramolecular host system was developed from non-chiral dicarboxylic acid and (1R, 2R)-diphenylethylenediamine via chirality transfer, which enabled highly efficient optical resolution of secondary alkyl alcohols by simple crystallization of host compounds from alcohol solution.     

Host-guest supramolecular interactions in the coordination compounds of 4,4'-azobis(pyridine) with MnX2 (X = NCS–, NCNCN–, and PF6(–)): structural analyses and theoretical study

Three new Mn(II) coordination compounds {[Mn(NCNCN)(2)(azpy)]·0.5azpy}(n) (1), {[Mn(NCS)(2)(azpy)(CH(3)OH)(2)]·azpy}(n) (2), and [Mn(azpy)(2)(H(2)O)(4)][Mn(azpy)(H(2)O)(5)]·4PF(6)·H(2)O·5.5azpy (3) (where azpy = 4,4'-azobis(pyridine)) have been synthesized by self-assembly of the primary ligands, dicyanamide, thiocyanate, and hexafluorophosphate, respectively, together with azpy as the secondary spacer. All three complexes were characterized by elemental analyses, IR spectroscopy, thermal analyses, and single crystal X-ray crystallography. The structural analyses reveal that complex 1 forms a two-dimensional (2D) grid sheet motif. These sheets assemble to form a microporous framework that incorporates coordination-free azpy by host-guest π···π and C-H···N hydrogen bonding interactions. Complex 2 features azpy bridged one-dimensional (1D) chains of centrosymmetric [Mn(NCS)(2)(CH (3)OH)(2)] units which form a 2D porous sheet via a CH(3)···π supramolecular interaction. A guest azpy molecule is incorporated within the pores by strong H-bonding interactions. Complex 3 affords a 0-D motif with two monomeric Mn(II) units in the asymmetric unit. There exist π···π, anion···π, and strong hydrogen bonding interactions between the azpy, water, and the anions. Density functional theory (DFT) calculations, at the M06/6-31+G* level of theory, are used to characterize a great variety of interactions that explicitly show the importance of host-guest supramolecular interactions for the stabilization of coordination compounds and creation of the fascinating three-dimensional (3D) architecture of the title compounds.