Supramolecular Features Research Articles

Study on supramolecular structural changes of ultrasonic treated potato starch granules

The supramolecular structural features of ultrasonic treated potato starch granules in excess water were investigated. Various ultrasonic treatments were used; an ultrasound probe set with different power (60, 105, 155 W) at a frequency of 20 kHz for 30 min. Scanning electron microscopy (SEM) images show that ultrasonic treatment induced notch and groove on starch granule surface. The B-type crystal structure was scarcely affected according to polarized light microscopy (PLM) and X-ray diffraction (XRD) analysis. However, Small-angle X-ray scattering (SAXS) data manifest that fractal structures changed from surface fractal into mass fractal as the ultrasonic power increased, indicating that the compact starch granules swelled to a larger extent and loosed. The repeat cluster thickness was unchanged. The electron density contrast between the crystalline and the amorphous lamella decreased, while the electron density difference between the amorphous lamella and amylose background increased. Moreover, the molecular order in crystalline lamella was reduced. These results demonstrated that ultrasonic treatment affected cluster structure, especially the crystalline region, and amylose background was affected more compared to amylopectin amorphous lamella.

Selenacalix[3]triazines: synthesis and host–guest chemistry

The heteracalixarene series (N/O/S) has been expanded with Se-bridged cyclotrimeric macrocycles. Selenacalix[3]triazines were synthesized by convenient one-pot nucleophilic aromatic substitution reactions and they showed peculiar supramolecular features. The N tridentate binding pocket was capable of coordinating both copper ions and anions.

Synthesis and Structural Characterization and Thermal Properties of a Novel Aza‐aromatic Base Adduct of Cadmium Thenoyltrifluoroacetonate: A precursor for Pure Phase Nano‐sized Cadmium(II) Oxide

AbstractA novel aza‐aromatic base adduct of cadmium(II) thenoyltrifluoroacetonate, [Cd(phen)(ttfa)2] (1), (phen = 1, 10‐phenanthroline; ttfa = thenoyltrifluoroacetonate) was synthesized and characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopy, thermal analysis as well as X‐ray crystallography. The single‐crystal structure of this complex shows that the coordination number of the Cd2+ ions are six with two nitrogen donor atoms from aza‐aromatic base ligands and four oxygen donors from two thenoyltrifluoroacetonate ligands. The supramolecular features in these complexes are directed by weak directional intermolecular interactions. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are in agreement with the crystal structure. The CdO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The average size of the nanoparticles was estimated by the Scherrer equation with the diameter about 45 nm. The morphology and size of the prepared CdO samples were further observed using SEM.

Synthesis, Structural Investigation and DFT Calculations of Cadmium (II) Fluorine-Substituted β-Diketonate: A Precursor to Producing Pure Phase Nano-Sized Cadmium (II) Oxide

A novel aza-aromatic base adduct of a cadmium(II) fluorine-substituted β-diketonate, [Cd(dmp)(ttfa)2]n(1), (“dmp” is an abbreviation for 2,9-dimethyl-1,10-phenanthroline and “ttfa” is an abbreviation for thenoyltrifluoroacetonate) was synthesised and characterised by elemental analysis and IR, 1H NMR and 13C NMR spectroscopy and studied by thermal as well as X-ray crystallography. The single-crystal structure of this complex shows that the coordination number of the Cd2+ ion is six with two N-donor atoms from the dmp ligand and four O-donors from ttfa. Self-assembly of this complex was mediated by CH···F–C and π–π stacking interactions. The supramolecular features of these complexes are controlled by weak directional intermolecular interactions. The structural energy of the title complex was determined by density functional theory calculations. The calculated HOMO–LUMO gap is 0.131 a.u. (3.474 eV). The CdO nano-particles were obtained by thermolysis of 1 at 180 °C with oleic acid as the surfactant. Scanning electron microscopy showed that the size of the CdO particles is ~35 nm.

Stigmasterol-Based Novel Low Molecular Weight/Mass Organic Gelators

Conjugates consisting of stigmasterol and L-phenylalanine, interconnected through short-chained dicarboxylic acyls by ester and amide bonds, respectively, were synthesized as potential low molecular weight/mass organic gelators (LMWGs/LMMGs). Their physico-chemical properties were subjected to investigation, especially their ability to form gels reversibly based on changes of the environmental conditions. Other self-assembly properties detectable by UV-VIS traces were measured in systems consisting of two miscible solvents (water/acetonitrile) with varying solvent ratios and using constant concentrations of the studied compounds. Partition and diffusion coefficients and solubility in water were calculated for the target conjugates. The conjugate 3a was the only compound from this series capable of forming a gel in 1-octanol. All three conjugates 3a–3c displayed supramolecular characteristics in the UV-VIS spectra.

N-(4-Chlorophenyl)-3-nitropyridin-2-amine

In the title compound, C11H8ClN3O2, the presence of intra­molecular N—H⋯O and C—H⋯N inter­actions help to establish an almost planar mol­ecule [dihedral angle between the pyridine and benzene rings = 9.89 (8)° and r.m.s. deviation for all 17 non-H atoms = 0.120 Å]. Supra­molecular tapes feature in the crystal packing whereby dimeric aggregates sustained by pairs of C—H⋯O inter­actions are connected by π–π inter­actions occurring between translationally related pyridine rings and between translationally related benzene rings along the b axis [centroid–centroid distance = length of b axis = 3.8032 (4) Å].

Networks based on hydrogen-bonds containing phosphorus anions and tris(3,5-dimethylpyrazolyl)borate nickel(II) moieties

Five structural kinds of nickel hydrogen-bonded networks containing hydrotris(3,5-dimethylpyrazolyl)borate ligands (Tp ∗) have been elucidated by X-ray diffraction, [Tp ∗Ni(OH 2) 3][( p-NO 2C 6H 4O) 2PO 2] ( 4), [Tp ∗Ni(OH 2) 3][Me 2PO 2]·Me 2P(O)OH ( 5), [Tp ∗Ni(OH 2) 3][( nBuO) 2PO 2]·0.5H 2O ( 6), [(Hpz)Tp ∗Ni(OH 2) 2][(Ph)PO 2OH] ( 7) and [Tp ∗Ni(OH 2) 2(Me 2PO 2)] ( 8). The most relevant supramolecular feature of complexes 4– 8 is all of them form coordination networks based on hydrogen bonds between water molecules and phosphate, phosphonate or phosphinate anions. These hydrogen bonds are formed within the monomer units in addition to connect monomers along the chains. Their behaviors in solution were investigated by one- and two-dimensional 1H NMR techniques.

Synthesis and structural characterization of new dinuclear silver(I) complexes: Different coordination modes of substituted 1,2,4-triazine ligands

Abstract Two new binuclear silver(I) complexes of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT) and 3,5,6-tris(2-pyridyl)-1,2,4-triazine (TPT) ligands, [Ag2(PDT)2(NO3)2], 1, and [Ag2(TPT)2(NO3)2], 2, have been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy, and also studied by thermal and electrochemical analysis as well as by X-ray crystallography. The individual dinuclear complexes in 1 are extended into a one-dimensional layered structure by weak Ag···CPDT (η3) interactions. The interesting features of the Ag(I) complexes are the different coordination modes of the ligands. The supramolecular features in these complexes are controlled by weak directional intra and intermolecular interactions.

Synthesis and characterization of lead(II) complexes with substituted 2,2′-bipyridines, trifluoroacetate, and furoyltrifluoroacetonate

Two substituted 2,2′-bipyridine lead(II) complexes, [Pb(5,5′-dm-2,2′-bpy)(tfac)2] n (1) (5,5′-dm-2,2′-bpy = 5,5′-dimethyl-2,2′-bipyridine and tfac = trifluoroacetate) and [Pb2(4,4′-dmo-2,2′-bpy)2(ftfa)4] (2) (4,4′-dmo-2,2′-bpy = 4,4′-dimethoxy-2,2′-bipyridine and ftfa = furoyltrifluoroacetonate), have been synthesized and characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopies, thermal behavior, and X-ray crystallography. Complexes 1 and 2 are 1D coordination polymer and dinuclear complex, respectively. The supramolecular features in these complexes are guided by weak directional intermolecular interactions.

Two new lead(II) coordination polymer and discrete complex containing bipyridine ligands with different positioned methyl substituents: synthesis, characterization, crystal structure determination, and luminescent properties

Lead(II) coordination polymer [Pb(5,5′-dmbpy)(μ-NO3)2] n (1) and mononuclear complex [Pb(6,6′-dmbpy)(NO3)2] (2) (where 5,5′-dmbpy is 5,5′-dimethyl-2,2′-bipyridine and 6,6′-dmbpy is 6,6′-dimethyl-2,2′-bipyridine) were synthesized from reaction of lead(II) nitrate with 5,5′-dmbpy and 6,6′-dmbpy, respectively. Both complexes were thoroughly characterized by elemental analysis, infrared, 1H and 13C NMR, UV–Vis, emission spectroscopy, as well as single-crystal X-ray diffraction. Polymer 1 possesses one-dimensional (1D) chain structure, whilst complex 2 exhibits a discrete complex which provide an extended chain parallel to the [001] direction, via weak intermolecular C–H···O hydrogen bonding. Coordination number of Pb2+ in 1 and 2 are 8 and 6, respectively, with the stereochemically active lone pair, resulting in the hemidirected geometry for both complexes. The nitrate anions exhibit a tridentate chelating/bridging mode in 1, and a bi-chelating mode in 2. The supramolecular features in these complexes are guided/influenced by weak directional intermolecular C–H···O hydrogen bonding (1 and 2) together with π–π and C–H···π (1) interactions. The luminescence studies of 1 and 2 confirmed that the position of methyl substituent on 2,2′-bipyridine rings has a profound effect on the fluorescence emissions.

A Universal Method for Detection of Amyloidogenic Misfolded Proteins

Diseases associated with the misfolding of endogenous proteins, such as Alzheimer's disease and type II diabetes, are becoming increasingly prevalent. The pathophysiology of these diseases is not totally understood, but mounting evidence suggests that the misfolded protein aggregates themselves may be toxic to cells and serve as key mediators of cell death. As such, an assay that can detect aggregates in a sensitive and selective fashion could provide the basis for early detection of disease, before cellular damage occurs. Here we report the evolution of a reagent that can selectively capture diverse misfolded proteins by interacting with a common supramolecular feature of protein aggregates. By coupling this enrichment tool with protein specific immunoassays, diverse misfolded proteins and sub-femtomole amounts of oligomeric aggregates can be detected in complex biological matrices. We anticipate that this near-universal approach for quantitative misfolded protein detection will become a useful research tool for better understanding amyloidogenic protein pathology as well as serve as the basis for early detection of misfolded protein diseases.

Sodium thiosulfonate salts: Molecular and supramolecular structural features and solution radiolytic properties

Three sodium thiosulfonate salts, NaMeS(2)O(2)·H(2)O, NaPhS(2)O(2) and NaMeC(6)H(4)S(2)O(2) have been prepared by the direct reaction of the sodium sulfinate salts with elemental sulfur, a clean, benign route that produces no by-products. The structures of the phenyl (which crystallised as a hydrate, NaPhS(2)O(2)·1.5H(2)O) and p-tolyl compounds were determined by X-ray crystallography. For the p-tolyl derivative, NaMeC(6)H(4)S(2)O(2), the unexpected coordination of the pendant sulfur atom was found, a feature not reported previously for thiosulfonate salts, and observed only in two of the more common thiosulfate salts. Intermolecular CH/π interactions are postulated to contribute to the driving force of sulfur coordination, otherwise a different orientation of the aromatic rings would be expected. For NaPhS(2)O(2)·1.5H(2)O, the water ligands and thiosulfonate anions each contribute three oxygen atoms to form a NaO(6) coordination sphere. The thiosulfonate and water oxygens bridge to other sodium atoms forming a three-dimensional layer structure consisting of sheets of NaPhS(2)O(2)·1.5H(2)O with a hydrophilic interior layer, comprising the sodium ions, water ligands and -S(2)O(2)(-) groups, and a hydrophobic exterior formed by the phenyl substituent. The structure is further stabilised by an extensive H-bonding network between the ligated water and the non-coordinating thiosulfonate sulfur atom forming part of the hydrophilic layer and by weak intermolecular edge-to-face CH/π interactions between the sheets. Investigation of the radical chemistry of the three salts using pulse radiolysis indicated that oxidation of NaMeS(2)O(2)·H(2)O involves formation of a sulfur-centred radical rather than hydrogen abstraction from the methyl substituent, whereas oxidation of the aromatic ring is the preferred pathway for the phenyl and p-tolyl derivatives.

Synthesis, properties and crystal structures of new binuclear lead(II) complexes based on phenyl, naphthyl-containing fluorine β-diketones and substituted 2,2′-bipyridines

Four lead(II) complexes with substituted 2,2′-bipyridine adducts and β-diketonates ligands, [Pb(5,5′-dm-2,2′-bpy)(tfpb) 2] 2 1, [Pb(4,4′-dmo-2,2′-bpy)(tfpb) 2] 2 2, [Pb(4,4′-dm-2,2′-bpy)(tfnb) 2] 2 3 and [Pb(5,5′-dm-2,2′-bpy)(tfnb) 2] 2 4, (“4,4′-dm-2,2′-bpy”, “5,5′-dm-2,2′-bpy”, “4,4′-dmo-2,2′-bpy”, “Htfpb” and “Htfnb” are the abbreviations of 4,4′-dimethyl-2,2′-bipyridine, 5,5′-dimethyl-2,2′-bipyridine, 4,4′-dimethoxy-2,2′-bipyridine, 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, respectively) have been synthesized and characterized by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy and also studied by thermal and electrochemical as well as X-ray crystallography. The supramolecular features in these complexes are guided/controlled by weak directional intramolecular interactions.

Lead(II) and cadmium(II) complexes of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-p,p′-disulfonate with high thermal stability

Pb(II) and Cd(II) complexes, {[Pb2(PDTS)2(CH3OH)((H2O)2]⋅ H2O} n (1) and [Cd(PDTS)(H2O)4]⋅ 2H2O (2) (PDTS2− = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-p,p′-disulfonate), are synthesized and characterized by elemental analysis, infrared (IR), 1H-NMR spectroscopy, and thermal analysis. The single-crystal structure of 1 shows that the complex forms a 2-D polymeric network containing two types of Pb2+ with coordination number eight (PbN2O6). Both possess hemidirected coordination geometries. The single-crystal structure of 2 shows distorted octahedral geometry for cadmium(II), CdN2O4. These compounds are the first complexes of “PDTS2−”. The supramolecular features in these complexes are guided/controlled by hydrogen bonding and noncovalent intermolecular interactions.

Synthesis and Crystal Structure of Lead(II) Thenoyltrifluoroacetonate Complexes with Substituted 2,2' -Bipyridines: Interplay of Intermolecular Interactions in Crystals

Three substituted 2,2'-bipyridine adducts of lead(II) thenoyltrifluoroacetonate, [Pb(4,4'-dm-2,2’- bpy)(ttfa)2]2, 1, [Pb(5,5' -dm-2,2’-bpy)(ttfa)2]2, 2, and [Pb(4,4'-dmo-2,2’-bpy)(ttfa)2], 3, (4,4’ -dm- 2,2’-bpy, 5,5’-dm-2,2’-bpy, 4,4’-dmo-2,2’-bpy and ttfa are the abbreviations for 4,4’-dimethyl-, 5,5’-dimethyl-, and 4,4’-dimethoxy-2,2’-bipyridine, and thenoyltrifluoroacetonate, respectively) have been synthesized, characterized by elemental and thermal analysis, IR and 1H- and 13C-NMR spectroscopy, and studied by X-ray crystallography. The supramolecular features in these complexes are guided/controlled by weak directional intermolecular interactions.

Cyclodextrin-assisted assembly of stimuli-responsive polymers in aqueous media

This review explores the advances in stimuli-responsive polymeric inclusion complexes, comprising of cyclodextrins, in aqueous media. Cyclodextrin complexation allows these polymeric systems to possess tailored physical properties that permit them to form novel supramolecular structures. By including and combining stimuli-responsive characteristics, these special systems can transform into various morphologies when exposed to different kinds of external stimuli. A wide variety of these stimuli-responsive polyrotaxanes and functionalized cyclodextrin polymers that possess interesting supramolecular characteristics are discussed, with specific focus on pH-, temperature-, photo- and redox- sensitive systems. These unusual polymer/cyclodextrin systems provide a basis for many useful applications, such as drug delivery, environmentally friendly coatings, personal home care products, separation processes, food processing, and microelectronics.

Use of acid–base and redox chemistry to synthesize cobalt(III) and iron(III) complexes of a partially deprotonated triprotic imidazole-containing Schiff base ligand: Hydrogen bound 1D linear homochiral and zig-zag heterochiral supramolecular complexes

Aerial reaction of cobalt(II) perchlorate with H 3(1) [ H 3(1) is the tripodal ligand derived from the condensation of tris(2-aminoethyl)amine with three equivalents of imidazole-2-carboxaldehyde] in methanol and [FeH 3(1)(ClO 4) 2] with Fe(1) in acetonitrile results in the formation of [CoH 2L](ClO 4) 2 · H 2O and [FeHL]ClO 4 · CH 3CN , respectively. Mössbauer spectroscopy and variable temperature magnetic susceptibility indicate that [FeHL]ClO 4 · CH 3CN is a low spin iron(III) species. Both complexes were characterized by EA, IR, and single crystal structure determinations. Both complexes crystallize in the centrosymmetric monoclinic space group, P2 1/ c, so both enantiomers of the chiral complex are present. The supramolecular features of these complexes, caused by the partial deprotonation of the ligand and the resultant formation of imidazole–H···imidazolate hydrogen bonds, are different. [FeHL] + forms hydrogen bonds with molecules from adjacent cells of like chirality. This results in a linear homochiral array of iron complexes. In contrast, [CoH 2L] 2+ forms hydrogen bonds with a molecule from the same cell and one from another cell resulting in an 1D alternating heterochiral zig-zag chain.

Self-assembly of vesicles from the stacking of a dipodal F⋯H–N hydrogen bonded arylamide foldamer

In this paper, we report the synthesis and self-assembling behavior of an F⋯H–N hydrogen bonding-induced arylamide-based dipodal foldamer. SEM, AFM, TEM, and XRD studies reveal that this preorganized oligomer stacks to form vesicles in methanol–chloroform (10–70%) binary solvents due to the strong stacking interaction of the folded segments and the supramolecular polymeric feature of the dipodal molecule in the stacked state. In contrast, a simple folded molecule can give rise to vesicles only when the chloroform content is 45–55%.

Variations in Cellulosic Ultrastructure of Poplar

A key property involved in plant recalcitrance is cellulose crystallinity. In an attempt to establish the typical diversity in cellulose ultrastructure for poplar, the variation and distribution of supramolecular and ultrastructural features, including the fraction of crystalline cellulose forms $$ {\text{I}}_{\alpha } $$ and $$ {\text{I}}_{\beta } $$ , para-crystalline cellulose and amorphous cellulose content were characterized. In this study, the percent crystallinity (%Cr) and lateral fibril dimensions of cellulose isolated from poplar were determined for 18 poplar core samples collected in the northwestern region of the USA.

Synthesis, structure and luminescence properties of lanthanide complex with a new tetrapodal ligand featuring salicylamide arms

A new tetrapodal ligand 1,1,1-tetrakis{[(2′-(2-furfurylaminoformyl))phenoxyl]methyl}methane (L) has been prepared and their coordination chemistry with Ln III ions has been investigated. The structure of {[ Ln 4L 3(NO 3) 12]·H 2O} ∞ ( Ln=Nd, Eu)] shows the binodal 4,3-connected three-dimensional interpenetration coordination polymers with topology of a (8 6) 3(8 3) 4 notation. [DyL(NO 3) 3(H 2O) 2]·0.5CH 3OH and [ErL(NO 3) 3(H 2O) (CH 3OH)]·CH 3COCH 3 is a 1:1 mononuclear complex with interesting supramolecular features. The structure of [NdL(H 2O) 6]·3ClO 4·3H 2O is a 2:1 mononuclear complex which further self-assembled through hydrogen bond to form a three-dimensional supramolecular structures. The result presented here indicates that both subtle variation of the terminal group and counter anions can be applied in the modulation of the overall molecular structures of lanthanide complex of salicylamide derivatives due to the structure specialties of this type of ligand. The luminescence properties of the Eu III complex are also studied in detail.