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Two novel compounds [Zn(bitmb)(L)]·2H2O and [Co(bitmb)(L)]·2H2O are prepared under hydrothermal conditions (bitmb = 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene; H2L = 1,3-bis-(4-carboxy-phenoxy)propane) and characterized by the single crystal X-ray diffraction analysis. Both complexes are isostructural and contain 3-fold right-handed helical 1D chains. IR and PXRD spectra, TG curves, and photoluminescent properties are also studied. [ABSTRACT FROM AUTHOR]

Abstract: The reactions of 2,6-di(2-oxazolyl)pyridine (L1), 2-[(S)-4-phenyl-2-oxazolyl]quinoline (L2) and 2-[(S)-4-isopropyl-2-oxazolyl]quinoline (L3) with silver nitrate yield three new complexes {[Ag5(L1)5]-(NO3)5}n (I), [Ag(L2)(NO3)] (II), and [Ag(L3)(NO3)(CH3CN)] (III), which have been fully characterized by single-crystal X-ray diffraction (CIF files nos. 1553091, 1553092, and 1559788, respectively), IR spectroscopy, and elemental and thermogravimetric analyses. Complex I shows a helical chain structure and the spiral directions of the chains are opposite, resulting in an achiral meso structure. Both II and III display discrete mononuclear structures. Fluorescence and non-linear optical (NLO) properties of the complexes were investigated. [ABSTRACT FROM AUTHOR]

A novel zinc complex with the formula [Zn(hfac)2(L1)]n (1) (L1 = bis(4-(1H-imidazol-1-yl)phenyl)methanone) is synthesized and structurally characterized by IR, elemental analyses, and the single crystal X-ray diffraction analysis. The zinc(II) ions of 1 are in a distorted octahedral environment with four O atoms of the hfac ligands and two N atoms from two L1 ligands. Each L1 acts as a bridging ligand to link two Zn(II) atoms to form a helical chain. [ABSTRACT FROM AUTHOR]

This study is concerned with the rotary motions of helical chains that play essential roles in the functions of molecular motors in biological systems. While the standard pictures for the rotary motions of molecular motors may be more or less like the rotations of rigid bodies, this study explores a qualitatively different mechanism for the rotary motions. We take a simple model of a helical chain and highlight its geometric angle shifts induced by internal twist propagation. Such angle shifts, which we call geometric somersaults, can generally arise even under the conditions of zero total angular momentum, and are thereby analogous to the somersault of a falling cat. Helical chirality of the chain and the direction of twist propagation are the decisive factors that determine the direction of the resulting somersaults. As an application, we argue that the geometric somersaults of the helical chain may serve as a prototypical model for the rotary motions of the central shaft of ATP synthase. [ABSTRACT FROM AUTHOR]

The reaction of the deprotonated form of the Schiff base ligand; (E)-2-methoxy-6-((phenylimino) methyl)phenol (L) with nickel chloride hydrate results in the formation of the 1-dimentional coordination polymer; Na[Ni(L)(OMe)(MeOH)] ( 1). The structure was determined via single crystal X-ray diffraction measurements. A careful analysis of the complex shows that the polymer exists as a helical structure, where the helicity is brought about by the presence of an alkali metal ion which is observed for the first time. Moreover the helical structure in 1 is maintained predominantly through covalent bond rather than supramolecular interactions. Direct current magnetic susceptibility measurement suggests that complex 1 obeys the Curie law. The fitting of magnetic data using the PHI software package yields parameters of S = 1, g = 2.26 and D = +4.51 (or D = −7.24 cm) for 1. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The Zn/Cd(II)-nbdc carboxylate motifs mediated by various dipyridyl-typed ligands afforded three new coordination compounds, namely, [Zn(nbdc)(bpa)(HO)]·HO ( 1), [Zn(nbdc)(bpp)]·HO ( 2), and [Cd(nbdc)(bpe)(HO)] ( 3) (Hnbdc = 4-nitrobenzene-1,2-dicarboxylic acid, bpa = 1,2-bi(4-pyridyl)ethane, bpe = 1,2-di(4-pyridyl)ethylene, and bpp = 1,3-bis(4-pyridyl)propane), which were synthesized by hydrothermal reaction and characterized by elemental analysis, IR, thermal analysis (TGA), and fluorescent analysis. The single-crystal X-ray diffractions reveal that three complexes display a diverse range of connectivity topology from 1D to 3D, which is dependent on the type of dipyridyl-typed ligands and metal centers. Complex 1 is the 1D chain featuring Zn-carboxylate binuclears extended further by bpa coligands. Complex 2 is the 2D thick-layer containing double-stranded chains cross-linked further by bpp coligands. Complex 3 is the 3D framework with (6)(6.8) ins topology featuring Cd-carboxylate chiral layers pillared by bpe coligands. The thermal stabilities and fluorescence properties for complexes 1- 3 are investigated. [ABSTRACT FROM AUTHOR]

Two new Cd(II) coordination polymers, namely [Cd(HOA)(μ-HO)(HO)]·3 nHO (1) and [Cd(HOA)(phen)]· nHO ( 2) (HOA = 3,3′,4,4′-oxidiphthalic acid, phen = 1,10-phenanthroline) have been synthesized by combining HOA or HOA and phen with Cd(II) salts under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 features a hydrogen-bond directed two-dimensional (2D) layered structure constructed from alternating left- and right-handed double strand helical chains, 2 represents a one-dimensional (1D) chain structure with the phen molecules dangling on it, which is further extended into a three-dimensional (3D) supramolecular framework through strong face-to-face π···π interactions. In addition, luminescent properties of these two compounds were also investigated in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

Two new novel ferrocenylaclyhydrazone-based receptors FcL and FcL were prepared and characterized by H NMR, IR, elemental analysis. X-ray crystallographic reveals that FcL belongs to Monoclinic system, with space group P2(1)/c, and FcL belongs to Hexagonal system with space group P6(5). It forms a novel helical chain by self-assembly. The electrochemical studies reveal that the formal potential ( E) of FcL and FcL show a gradual decrease in the order Fc(Ferrocene) < FcL < FcL and FcL is responsive to Pb. The maximum electrochemical shift of FcL for Pb is about 44 mV. FcL shows selective potential response to Pb(II) ion. [ABSTRACT FROM AUTHOR]

The reactions of 3(5)-(4-methoxyphenyl)-5(3)-phenyl-1 H-pyrazole ( L) with nitric acid and 5-(4-benzyloxyphenyl)-3-(furan-2-yl)-1 H-pyrazole( L) with hydrochloric acid produced [H L · NO] (Salt- 1) and [H L · Cl] (Salt- 2). The structures of Salt- 1 and Salt- 2 were determined by single crystal X-diffraction. In Salt- 1, H L showed [2 + 2] binding of NO ions in the solid state to form dimer architecture with R(4) and R(14) graph sets. An anion directed one-dimensional anion-assisted helical chain with active participation of the chloride ion and protonated pyrazole via N-H···Cl hydrogen bonding in Salt- 2. In addition, the protonated H L molecules interacted with each other through weak C-H···π interactions resulting in the formation of another one-dimensional helical chain. [ABSTRACT FROM AUTHOR]

A novel metal-organic framework {[Cu(Hbptc)(cbpy)(HO)]·(HO)} ( 1) has been hydrothermally synthesized through reaction of 1,1′-biphenyl-2,2′,3,3′-tetracarboxylic acid (Hbptc) with Cu(II) salt in the presence of ancillary nitrogen ligand 5,5′-dimethyl-2,2′-bipyridine (cbpy), and its structure was determined by X-ray diffraction and characterized by elemental analysis, and IR spectrum. The title compound crystallizes in monoclinic space group P2/ c. Both right- and left-handed helices are detected in the structure. In the ab-plane, adjacent chains are homochiral and parallel to each other, which are connected together by hydrogen bonds to form a 2D supramolecular structure. The supramolecular layers with opposite chirality are arranged alternatively along the c-axis to form a 3D mesomeric supramolecular structure through π···π interactions. The thermal stability of the complex 1 was studied by thermal gravimetric and differential thermal analysis. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and crystal structure of the title compound, ( S)-2-(2-hydroxynaphthalen-6-yl)- N-((pyridin-4-yl)methyl) propanamide, is described. The salt is enantiomerically pure and crystallize in the orthorhombic P222 chiral space group with a = 7.9174(13) Å, b = 11.1583(18) Å, c = 11.2600(18) Å. Each molecule is linked to four neighboring molecules through the O-H···O and N-H···N hydrogen bonds into a supramolecular helical chain. The O-H···O and N-H···N hydrogen bonds lead to 24-membered open rings. Chains are further connected into layers via extensive interchain H···O and H···C short contacts. Graphical Abstract: The structure of ( S)-2-(2-hydroxynaphthalen-6-yl)- N-((pyridin-4-yl) methyl) propanamide, is described and prominent intermolecular O-H···O and N-H···N hydrogen bonds are present in the structure.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A cadmium(II) coordination polymer [Cd(2-mBIM)Cl(CHO)(HO)(HO)] ( 1) (wherein 2-mBIM = bis(2-methylimidazo-1-yl) methane, CHO = succinate anion) has been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in the monoclinic space group C2/ c with a = 23.5265(15) Å, b = 7.3558(5) Å, c = 17.4771(11) Å, β = 90.3560(10)°, V = 3024.5(3) Å, Z = 4. Each Cd(II) atom is octahedrally coordinated and connected with two adjacent Cd(II) atoms by two individual 2-mBIM ligands in a trans-configuration to form one-dimensional (1D) helical structure. Such 1D helical chain structures were connected to each other via the succinate anion ligands and result in the formation of a two-dimensional (2D) framework. Meanwhile, an overall three-dimensional (3D) supramolecular network was formed via the weak hydrogen bond interactions between metal-coordination and free water molecules. Graphical Abstract: A cadmium(II) coordination polymer has been synthesized and its single crystal structure shows that an overall 3D supramolecular network was formed via the weak hydrogen bond between adjacent 2D layer framework containing 1D helical chain structure. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]