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Chiral metal-organic frameworks (CMOFs) [Ni((L)-ccba)(1,3,5-tmib)(H2O)0.5]n (HU17-L) and [Ni((D)-ccba)(1,3,5-tmib)(H2O)0.5]n (HU17-D) were prepared from alanine derivatives (L)-H2ccba and (D)-H2ccba in the presence of auxiliary N-donor linker 1,3,5-tmib (H2ccba = 4-((1-carboxyethyl)-carbamoyl)benzoic acid, 1,3,5-tmib = 1,3,5-tris(2-methyl-1H-imidazol-1-yl)benzene). HU17-L and HU17-D are three-dimensional (3D) enantiomers based on dinuclear [Ni2(CO2)2(H2O)]2+ clusters. Helical motifs are their outstanding structural features. In HU17-L and HU17-D, (L)-ccba2- and (D)-ccba2- anions constructed left-handed (L)-ccba-Ni chain and right-handed (D)-ccba-Ni chain through chiral transfer, respectively. Moreover, achiral 1,3,5-tmib linkers were bridged together by Ni(II) centers to obtain left-handed 1,3,5-tmib-Ni chain in HU17-L and right-handed 1,3,5-tmib-Ni chain in HU17-Dvia asymmetric induction, respectively. Topological analysis revealed that these frameworks are 8-connected fcu nets with point symbol (424.64). Magnetic tests indicate that antiferromagnetic interactions exist in these complexes. [ABSTRACT FROM AUTHOR]

In the presence of nitrogen heterocyclic compound 2,5-di(1 H -imidazole-1 -yl)pyridine (2,5-DIP), luminescent chiral synthons (R)-H 3 CTA and (S)–H 3 CTA assembled with Zn2+ ions to obtain enantiomers [Zn((R)-HCTA) (2,5-DIP)] n (HU14 -R ) and [Zn((S)-HCTA) (2,5-DIP)] n (HU14– S )) under hydrothermal condition, respectively. Partially deprotonated (R)-HCTA2- anions were bridged by Zn2+ ions to form small left-handed (R)-HCTA-Zn chain in HU14- R , while (S)-HCTA2- anions and Zn2+ ions were connected together resulting in enantiomeric right-handed chain in HU14– S . Moreover, larger left-handed (R)-HCTA-Zn-2,5-DIP chain and right-handed (S)-HCTA-Zn-2,5-DIP chain were found in HU14 -R and HU14– S , respectively. These helical building blocks were joined together to create a pair of 3D frameworks with dia net, which show strong fluorescent characteristic and circular dichroism response. Further tests proved that HU14 -R and HU14– S have circularly polarized light (CPL) activity and their luminescence anisotropy factors (g 1um) at 358 nm are +0.00346 and −0.00157, respectively. Moreover, as fluorescent probes, they have high stability, reliability and interference detection rate, and detection limits are up to 2.80 × 10−6 M for Cr 2 O 7 2− and 6.19 × 10−6 M for MnO 4 −. [Display omitted] • Chiral synthon with bright fluorescence. • Circular polarization luminescence activity. • High sensitivity and selective recognition for Cr 2 O 7 2− and MnO 4 − ions. [ABSTRACT FROM AUTHOR]

Luminescent cuprous complexes are of great importance among coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title heteroleptic cuprous polymer solvate, catena‐poly[[[(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis(diphenylphosphane)‐κ2P,P′](μ‐pyridine‐3‐carbonitrile‐κ2N1:N3)copper(I)] hexafluorophosphate dichloromethane trisolvate], {[Cu(C6H4N2)(C39H32OP2)]PF6·3CH2Cl2}n, conventionally abbreviated as {[Cu(3‐PyCN)(Xantphos)]PF6·3CH2Cl2}n, where Xantphos and 3‐PyCN represent (9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis(diphenylphosphane) and pyridine‐3‐carbonitrile, respectively, has been described. In this polymer solvate, the asymmetric unit consists of three dichloromethane solvent molecules, a hexafluorophosphate anion and a polymeric heteroleptic cuprous complex cation, in which the cuprous centre is in a CuP2N2 tetrahedral coordination and is coordinated by two P atoms from the Xantphos ligand and two N atoms from two 3‐PyCN ligands (the pyridyl and cyano N atoms). It is through the connection of the μ2‐bridging 3‐PyCN ligand that these cuprous centres are linked into a one‐dimensional helical chain structure. The chains are further assembled through C—H...π interactions to form a supramolecular metal–organic framework containing solvent‐accessible channels. The UV–Vis absorption and photoluminescence properties of this heteroleptic cuprous polymer have been studied on as‐synthesized samples. Its luminescence emission should mainly originate from the metal‐to‐ligand charge transfer excited state. [ABSTRACT FROM AUTHOR]

• A new anionic Mn-organic framework with 1D helical chain SBUs was obtained. • The Eu@Mn-MOF was successfully constructed by post-synthetic modification approach. • The Eu@Mn-MOF exhibits a high-performance ratiometric sensing of temperature. The development and construction of smart luminescent MOF materials are highly desired. For the construction of luminescent MOF with new network and smart responsiveness, the introduction of Ln3+ into porous materials by the post-synthetic modification approach is one of the most effective strategies. Herein, a new anionic Mn–organic framework with 1D helical chain SBUs, [(CH 3) 2 NH 2 ][Mn 3 (OH)(TATB) 2 ] (SQNU-24 , H 3 TATB = 4,4′,4″-s-triazine-2,4,6-triyltribenzoic acid, SQNU = Shangqiu Normal University), was successfully prepared under a DMF/CH 3 CN solvent system. Benefitting from the anionic skeleton, high porosity, double-walled structure and 1D helical chain SBUs within SQNU-24 , the dual-emitting Eu@SQNU-24 was successfully constructed by a post-synthetic modification approach. This work demonstrates the TATB3− ligand as an "antenna" can effectively sensitize Eu3+ ions. Interestingly, the dual-emitting Eu@SQNU-24 as a ratiometric thermometer exhibits a good temperature-responsive property. A new smart luminescent Eu@Mn–MOF was constructed by a post-synthetic modification approach. Interestingly, the dual-emitting Eu@Mn–MOF exhibits a good temperature-responsive property in the range of 80 to 220 K. [Display omitted] [ABSTRACT FROM AUTHOR]

Three new hexa-Ni-substituted Keggin-type polyoxometalates (POMs), [Ni6(OH)3- (DACH)3(H2O)6(PW9O34)]·31H2O (1), [Ni(DACH)2][Ni6(OH)3(DACH)3(HMIP)2(H2O)2(PW9O34)]·56 H2O (2), and [Ni(DACH)2][Ni6(OH)3(DACH)2(AP)(H2O)5(PW9O34)]·2H2O (3) (DACH = 1,2-Diami- nocyclohexane, MIP = 5-Methylisophthalate, AP = Adipate) were successfully made in the presence of DACH under hydrothermal conditions. 1 is an isolated hexa-Ni-substituted Keggin unit decorated by DACH. In order to further construct POM cluster-organic frameworks (POMCOFs) on the basis of 1, by analyzing the steric hindrances and orientations of the POM units, the rigid HMIP and flexible AP ligands were successively incorporated, and another anionic monomeric POM 2 and the new 1D POM cluster organic chain (POMCOC) 3 were obtained. HMIP ligand still acts as a decorating group on the Ni6 core of 2 but results in the different spatial arrangement of the {Ni6PW9} units. AP ligands in 3 successfully bridge adjacent isolated POM cluster units to 1D POMCOC with left-hand helices. The AP in 3 is the longest aliphatic carboxylic acid ligand in POMs, and the 1D POM cluster-AP helical chain represents the first 1D POMCOC with a helical feature. [ABSTRACT FROM AUTHOR]

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]

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Since 1999, when Takuzo Aida proposed the preparation of high density polyethylene (HDPE) crystalline nanofibers through polymerization of ethylene by a Cp2 TiCl2 /MCM-41 catalyst, many researchers have published various papers on different aspects of the idea. The published researches show that the endeavors to polymerize other types of alpha olefins, especially propylene, to obtain polyolefins with crystalline nanofiberous morphology have not been successful and no one has reported such morphology for them. In the present article, a possible reason behind these observations is proposed. Comparing the direction of the growth of HDPE chains and isotactic polypropylene (iPP) helices to become appropriate for making polymer crystals shows that HDPE chains are able to form crystal unit cells without concerning upward or downward chain growth direction, while the growth direction of adjacent iPP chains might be responsible for unsuccessful synthesis of crystalline iPP nanofibers in confined channels of the mesoporous catalysts. iPP helices can crystallize beside each other only in the form of anticline isochiral helices.

The reactions of (R)‐ and (S)‐4‐(1‐carboxyethoxy)benzoic acid (H2CBA) with 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene (1,3‐BMIB) ligands afforded a pair of homochiral coordination polymers (CPs), namely, poly[[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate], {[Zn(C10H8O5)(C14H14N4)]·H2O}n or {[Zn{(S)‐CBA}(1,3‐BMIB)]·H2O}n (1‐L), and poly[[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] monohydrate] (1‐D). Three kinds of helical chains exist in compounds 1‐D and 1‐L, which are constructed from ZnII atoms, 1,3‐BMIB ligands and/or CBA2− ligands. When the as‐synthesized crystals of 1‐L and 1‐D were further heated in the mother liquor or air, poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(S)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)], [Zn(C10H8O5)(C14H14N4)]n or [Zn{(S)‐CBA}(1,3‐BMIB)]n (2‐L), and poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene][μ‐(R)‐4‐(1‐carboxylatoethoxy)benzoato]zinc(II)] (2‐D) were obtained, respectively. The single‐crystal structure analysis revealed that 2‐L and 2‐D only contained one type of helical chain formed by ZnII atoms and 1,3‐BMIB and CBA2− ligands, which indicated that the helical chains were reconstructed though solid‐to‐solid transformation. This result not only means the realization of helical transformation, but also gives a feasible strategy to build homochiral CPs. [ABSTRACT FROM AUTHOR]

As a less explored avenue, actinide‐based metal‐organic frameworks (MOFs) are worth studying for the particularity of actinide nodes in coordination behaviour and assembly modes. In this work, an azobenzenetetracarboxylate‐based anionic MOF supported by uranyl–carboxyl helical chain units was synthesized, incorporating linear uranyl as the metal centre. This kind of helical chain‐type building unit is reported for the first time in uranyl‐based MOFs. Structural analysis reveals that the formation of helical chain secondary units can be attributed to restricted equatorial coordination of rigid flat azobenzene ligand to uranyl centres. Meanwhile, this newly‐synthesized anionic material has been used to remove Eu3+ ions, as a non‐radioactive surrogate of Am3+ ion, through an ion‐exchange process with [(CH3)2NH2]+ ions in its open channels, as evidenced by a combination of 1H NMR spectroscopy, EDS and PXRD. [ABSTRACT FROM AUTHOR]

Two coordination polymers of lead(II), 1D-{Pb(DFPT)(μ-Br)2}n (1) and 1D-helical-{Pb(DFPT)(μ-I)2}n (2), with 5,6-di(furan-2-yl)-3-(pyridin-2-yl)-1,2,4-triazine (DFPT) were prepared and identified by elemental analysis, FT-IR, 1H NMR spectroscopy and single-crystal X-ray diffraction. In the 1D-double chain-coordination polymers of 1 and 2, the lead atom has a PbNpyNtz(μ-X)4 (X: Br (1), I (2)) environment with distorted octahedral geometry and hemidirected coordination sphere. The type of the polymeric chain in both complexes is different; 1 has a linear expansion while 2 shows a helix structure with a racemic mixture of the P and M chains. In the crystal network of the complexes, in addition to hydrogen bonds, there are triazine···furyl and furyl···furyl ring π–π stacking interactions. The thermodynamic stability of the compounds, the polymer stability slope for pentameric chains (PSS5) and also the energy variation of the free DFPT ligand for 360° rotation of the pyridine ring were studied by DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract Linear and flexible N 4 ligand trien (N′-{2-(2-aminoethylamino)-ethyl}-ethane-1,2-diamine) has been used to show octahderal coordination around NiII ions and cis coordination from two ancillary bridges from azide ions. Room temperature reaction of trien with Ni(NO 3)·6H 2 O and NaN 3 has led to an end-to-end (EE) azido bridged one-dimensional NiII based helical coordination chain of formula [NiII(μ -N 3) 2 (trien)] n (NO 3)·H 2 O { 1 n ·(NO 3)·H 2 O}. Propagation of the chain in one dimension in a helical fashion is continued from the azido bridges in cis directions. Comparative reaction protocol using Co(NO 3) 2 ·6H 2 O on the other hand provided a discrete mononuclear octahedral cobalt (III) complex cis -[CoIII(N 3) 2 (trien)](NO 3)·2H 2 O { 2 ·(NO 3)·2H 2 O} due to different type of ligand wrapping having only terminal coordination from azide ions. Graphical abstract Image 1 Highlights • Trien ligand, NaN 3 with NiII and CoII salt has led to two different. • Comparative structural and experimental analysis of two complexes was made. • The crystal structures of NiII and CoII complexes were determined. • End-to-end (EE) azido bridging made 1D NiII helical structure. [ABSTRACT FROM AUTHOR]

Abstract With an aim to obtain a new supramolecular compound based on Keggin-type polyoxometalates with mixed-ligand: [Cu(I)(phen) 2 ] 2 {[Cu(II)] 2 (phen) 4 PTA}[H 3 PMoV 4 MoVI 8 O 40 ] (phen = 1,10-phenanthroline, PTA = terephthalic acid) has been synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR, X-ray single crystal diffraction, TG analyses and XPS. In the title compound, the Keggin-type phosphomolybates anions, butterfly-shaped [Cu(I)(phen) 2 ]+ subunits and dumbbell-shaped {[Cu(II)] 2 (phen) 4 PTA}2+ subunits are alternately connected to form chiral helical chains via hydrogen bonds along b axis, and the adjacent chiral helical chains are connected in the way of sharing butterfly-shaped [Cu(I)(phen) 2 ]+ subunits and dumbbell-shaped {[Cu(II)] 2 (phen) 4 PTA}2+ subunits to form 3D supramolecular reticular framework. As expected, the title compound with mixed-ligands (phen and PTA) has been successfully synthesized, inconceivably, the title compound also contains mixed-valence Cu (Cu(I) in butterfly-shaped [Cu(I)(phen) 2 ]+ subunits; Cu(II) in dumbbell-shaped {[Cu(II)] 2 (phen) 4 PTA}2+ subunits). The preliminary analyses show that mixed-valence Cu(I/II) may be due to the reduction of Cu(II) (from CuCl 2) to Cu(I) (in butterfly-shaped [Cu(I)(phen) 2 ]+ subunits) by N-containing compound. The successful results of this work provide a new idea that supramolecular materials with attractive structures and novel properties, which could be designed and synthesized by introducing of mixed-ligands into the supramolecular materials. Additionally, the electrocatalytic property of the title compound to H 2 O 2 has been studied. Graphical abstract Unlabelled Image Highlights • Compound based on Keggin POMs with mixed-ligand and Cu(I/II) was prepared. • The compound contains the right- and left-hand helical chains. • The compound exhibits good electrocatalytic activity towards H 2 O 2 reduction [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]

A flexible bis(pyridylurea) ligand, 1,1′-[oxybis(2,1-phenylene)] bis(3-pyridin-3-ylurea) (L), has been synthesized and characterized. The interaction of L with ZnCl 2 and CdCl 2 has been investigated. In the structure of {[ZnLCl 2 ]·2DMF} n ( 1 ), the flexible ligands bridge the Zn II centers to form 1D helical chains with a pitch of 9.743 Å. The P and M helical chains are arranged equally, and the whole complex 1 is racemic. In the structure of [CdLCl 2 (DMF)] n ( 2 ), the flexible ligands bridge Cd II centers to form one-dimensional P and M helical chain structures in a similar manner. Then the chlorine atoms act as bridges in bidentate modes linking the P helical chain with M helical chain to form a 1D looped chain coordination polymer. [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]

A new Co(II) complex, {[Co(MPA)(4,4′-bpy)(H 2 O)]·2H 2 O} n ( 1 ) (H 2 MPA = 4-methylphthalic acid, 4,4′-bpy = 4,4′-bipyridine), has been prepared under solvothermal condition and fully characterized. The X-ray crystallography test demonstrates that 1 exhibits two-dimensional (2D) layer structure in which the helical Co(II) chains linked by syn-anti carboxylate bridges are connected by 4,4′-bpy ligands. Weak ferromagnetism was observed on direct-current (dc) susceptibility due to the collective effects of the helical chain structure and antiferromagnetic couplings between Co(II) ions transmitted by μ 2 - 1,3-carboxylate groups. Interestingly, slow magnetic relaxation was observed in 1 at liquid helium temperatures without an external dc field. [ABSTRACT FROM AUTHOR]

In order to study the in vivo protective effect on myocardial ischemia, (20 S,24 R)-epoxydammarane-12β,25-diol, (V), and (20 S,24 S)-epoxydammarane-12β,25-diol, (VI), were synthesized through a novel synthetic route. Two key intermediates, namely (20 S,24 R)-3-acetyl-20,24-epoxydammarane-3β,12β,25-triol, (III) [obtained as the hemihydrate, C32H54O5·0.5H2O, (III a), and the ethanol hemisolvate, C32H54O5·0.5C2H5OH, (III b), with identical conformations but different crystal packings], and (20 S,24 S)-3-acetyl-20,24-epoxydammarane-3β,12β,25-triol, C32H54O5, (IV), were obtained during the synthesis. The structures were confirmed by 1H NMR, 13C NMR and HRMS analyses, and single-crystal X-ray diffraction. Molecules of (III a) are extended into a two-dimensional network constructed with water molecules linked alternately through intermolecular O-H...O hydrogen bonds, which are further stacked into a three-dimensional network. Compound (III b) contains two completely asymmetric molecules, which are linked in a disordered manner through intermolecular C-H...O hydrogen bonds. While the crystal stacks in compound (IV) are linked via weak C-H...O hydrogen bonds, the hydrogen-bonded chains extend helically along the crystallographic b axis. [ABSTRACT FROM AUTHOR]

Utilizing the lactic acid derivatives ( R )-4-(1-carboxyethoxy)benzoic acid (denoted: ( R )-H 2 CBA) and ( S )-4-(1-carboxyethoxy)benzoic acid (denoted: ( S )-H 2 CBA)as chiral linkers to self-assemble with 4, 4′-bipyridine (denoted: BIP) and Cd(II) ions, a couple of three-dimensional homochiral coordination polymers, namely [Cd 3 (( R )-CBA) 3 (BIP) 2 (H 2 O)]·xGuest ( 1-D ) and [Cd 3 (( S )-CBA) 3 (BIP) 2 (H 2 O)]·xGuest ( 1-L ), have been synthesized under solvothermal reaction condition. Single crystal X-ray diffraction analysis reveals the two complexes contain single helical chains based on enantiopure ligands and cadmium clusters. Moreover, some physical characteristics such as PXRD, thermal stability, solid-state circular dichroism (CD) and luminescent were also investigated. [ABSTRACT FROM AUTHOR]

The absolute structure of the title compound preaustinoid A1 [systematic name: (5aR,7aS,8R,10S,12R,13aR,13bS)-methyl 10-hydroxy-5,5,7a,10,12,13b-hexamethyl-14-methylene-3,9,11-trioxohexadecahydro-8,12-methanocycloocta[3,4]benzo[1,2-c]oxepine-8-carboxylate], C26H36O7, has been determined by resonant scattering using Cu Kα radiation [Flack parameter = 0.07 (15)]. The structure is consistent with that reported previously [Stierle et al. (2011). J. Nat. Prod. 74, 2272–2277], determined by detailed analysis of MS and NMR data. The molecule consists of a fused four-ring arrangement. The seven-membered oxepan-2-one ring has a chair conformation, as do the central cyclohexane rings, while the outer cyclohexa-1,3-dione ring has a boat conformation. In the crystal, molecules are linked via O—H...O hydrogen bonds, forming helical chains propagating along [100].

In the crystal of the title polymeric complex, [Cd(C12H8O4)(H2O)2]n, the CdII cation, located on a twofold rotation axis, is coordinated by two water molecules and chelated by two phenylenediacrylate anions (mpda) in a distorted octahedral geometry. The mpda anions bridge the CdII cations, forming helical chains propagating along the c-axis direction. The mpba anion has twofold symmetry with two benzene C atoms located on the twofold rotation axis. In the crystal, O—H...O hydrogen bonds link the polymeric helical chains into a three-dimensional supramolecular architecture.

Two complexes, {Mn(hfac)2(BIPMO)} n ( 1), {Cu(hfac)2(BIPMO)} n ( 2) [hfac=1,1,1,5,5,5-hexafluoro-pentane-2,4-dionato(-), BIPMO=bis(4-(1 H-imidazol-1-yl)phenyl)methanone], with the V-shaped ligands were synthesized and characterized by infrared spectroscopy, elemental analyses, along with single-crystal X-ray diffraction analyses. The X-ray diffraction studies have shown that the metal ions in 1 and 2 are both six-coordinated to two nitrogen atoms of two BIPMO ligands and four oxygen atoms of two hfac ligands to form a distorted octahedral geometry. Each BIPMO ligand acts as a bridging ligand to link two adjacent metal(II) atoms to form a helical chain in the crystal structure. [ABSTRACT FROM AUTHOR]

A new Co(II) coordination polymer, [Co(bda)(bpa)]n(1) [H2bda = 4,4′- benzophenonedicarboxylic acid and bpa = bis(4-pyridyl)amiine], has been prepared by hydrothermal synthesis and characterized by IR, X-ray diffraction, and elemental analysis. Complex [Co(bda)(bpa)]n(1), triclinic system, space groupP-1 witha= 12.015(5) Å,b= 13.195(5) Å,c= 16.922(5) Å, α = 104.801(5)°, β = 90.028(5)°, γ = 116.953(5)°,V= 2290.9(15) Å3,Z= 2,Mr= 498.35,Dc= 1.445 g/cm3,F(000) = 1020, and µ = 0.791 mm−1. The final refinement gaveR= 0.0360andwR= 0.0450 for 8127 reflections withI> 2σ(I). X-ray diffraction analysis reveals that complex1shows a two-dimensional layer structure with one-dimensional helical chains. [ABSTRACT FROM AUTHOR]

ABSTRACT Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by 1H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε*, where ε* is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε*, however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random-coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media. © 2015 Wiley Periodicals, Inc. Biopolymers 105: 191-198, 2016. [ABSTRACT FROM AUTHOR]

In this research, we explore the structural, electronic and optical properties of t-Se 1-x Te x and t-Se 1-x Te x containing a defect (t-Se 1-x Te x (D)) in the dihedral angle (φ) for low concentrations (x = 0.03, 0.04 and 0.08) utilizing WIEN2k code. The structural properties, especially, the helical chain constants of t-Se 1-x Te x change by x concentration compared to t-Se; this change is very identical to the experimental results. Moreover, our defect affects these constants. The electronic properties show that our systems are semiconductors, it also show that the gap decreases when increasing x in t-Se 1-x Te x compared to t-Se. likewise, when we introduce the defect in t-Se 1-x Te x , this is mostly due to the change in the p-orbital. Hence, intra-chain interactions have a role in determining the gap value for our systems; this is proven by the defect in φ. The optical properties show changes confirming the charge density distributions results and the anisotropic nature of our systems. [ABSTRACT FROM AUTHOR]

Two new inorganic–organic hybrids, (H ampy )Zn 2 (PO 4 ) (HPO 3 ) ( 1 ) and ( ampy )Zn 2 (HPO 3 ) 2 ( 2 ), where ampy = 3-(aminomethyl)pyridine, have been solvothermally prepared and structurally characterized. Compound 1 exhibits an unusual two-dimensional layer structure, which possesses a central 4.8 2 zincophosphate sheet wrapped by infinite zincophosphite chains. Left- and right-handed helical chains participate in the formation of the zincophosphate layer. Compound 2 features a three-dimensional pillared-layer structure, in which two-dimensional Zn II (HPO 3 ) inorganic sheets were cross-linked by ampy ligands. The simultaneous occurrence of zinc-amine helical chains in 2 is unique and, to the best of our knowledge, firstly encountered in phosphite/phosphate hybrid materials. Different coordination modes and roles of the same ampy ligand were observed in the formation of the hybrid structures. [ABSTRACT FROM AUTHOR]

The tridentate N-donor ligand 2,6-di(2-oxazolyl)pyridine (L) reacts with AgClO4 and AgPF6 to yield two new complexes, {[Ag5(L)5](ClO4)5} n ( 1) and {[Ag5(L)5](PF6)5} n ( 2), which have been characterized by single-crystal and powder X-ray diffractions, IR spectroscopy, and elemental and thermogravimetric analyses. Complexes 1 and 2 are isotypic, displaying helical chain structures. The fluorescence properties of 1 and 2 were investigated. [ABSTRACT FROM AUTHOR]

The coordination compounds [Cd(TBDS)(H2O)2] n ( 1) and Cd(TBDS)(bpy)2(H2O) ·3H2O ( 2) {H2TBDS = 4-([4,2′:6′,4′′-terpyridine]-4′-yl)benzene-1,3-disulfonic acid, bpy = 2,2′-bipyridine} were synthesized under hydrothermal conditions. Single crystal X-ray diffraction analyses revealed that compound 1 is a twofold interpenetrating 3D framework with 4-connected dia topology, whereas compound 2 is a mononuclear compound, which packed with each other via hydrogen-bonding interactions to construct a three-dimensional supramolecular structure, and contained unusual meso-helical chains. Additionally, the luminescence properties and thermal stabilities of 1 and 2 were investigated. [ABSTRACT FROM AUTHOR]

The reaction of 2-hydroxyphenylpropanone oxime (Et-H 2 salox) with Mn(NO 3 ) 2 ·4H 2 O, NEt 3 and 1,3-bis(4-pyridyl)propane-N,N′-dioxide (bppo) in EtOH/H 2 O mixture afforded a one-dimensional coordination polymer with the formula [Mn 3 O(Et-salox) 3 (bppo)(MeOH)(H 2 O) 3 ](NO 3 ) 0.5 (Et-Hsalox) 0.5 ·MeOH·H 2 O ( 1 ·MeOH·H 2 O). 1 ·MeOH·H 2 O had a manganese triangle structure, [Mn III 3 O] 7 + , which was used as a building unit for a subsequent assembly of an oximate and central oxide. The flexible bppo ligand linked the units, resulting in the formation of a 1D helical structure. Variable temperature direct current magnetic susceptibility measurements of complex 1 ·MeOH·H 2 O were carried out. Exchange interactions of the metal centers of complex 1 ·MeOH·H 2 O were examined, and the results indicate that both ferro- and antiferromagnetic interactions simultaneously coexist in 1 ·MeOH·H 2 O, resulting in an S = 2 ground state. Moreover, complex 1 ·MeOH·H 2 O shows the frequency dependence of the out-of-phase component in alternating current magnetic susceptibility measurements, indicating single-molecule magnet behavior with U eff = 28 K and τ 0 = 1.8 × 10 − 9 s. [ABSTRACT FROM AUTHOR]

A novel chiral purely organic crystal [( A )(H A + HSO 4 − ) 2 ]⋅2H 2 O ( 1 ) ( A = 2-(imidazo [1,2- a ]pyridin-2-yl)-2-oxoacetic acid) has been obtained through diffusion of acetone into sulfuric acid aqueous solution of A . This crystal was characterized by the elemental analysis, IR spectrum and the single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, chiral space group P 2 1 , with a = 10.092(2) Å, b = 15.641(3) Å, c = 10.551(2) Å, β = 101.62(3)°, and Z = 2. Compound 1 reveals left-handed 2 1 helical chain assembled by hydrogen bond and hydrophobic (short atomic contact) interactions, in which spontaneous resolution occurs. The left-handed chirality of the original helical chain is transferred uniformly to adjacent chain in a homochiral manner, through interchain hydrogen bond and hydrophobic interactions, resulting in the formation of chiral layer. Compound 1 also exhibits green phosphorescence. [ABSTRACT FROM AUTHOR]

Two isostructural polyoxometalate-based inorganic–organic hybrids with 1D helical chain, [CuH 3 L 2 (GeMo 12 O 40 )]·2H 2 O ( 1 ) and [CuH 3 L 2 (SiMo 12 O 40 )]·2H 2 O ( 2 ), where L =2,4,5-tri(4-pyridyl)-imidazole have been synthesized under hydrothermal conditions. It is the first time to use the L ligand to synthesis the Keggin-type polyoxometalate-based inorganic–organic hybrids. The two compounds possess the left- and right-handed helical chains and the POMs as pendants attach in the helical chains through Cu–O bonds. The two compounds have been characterized by elemental analyses, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA) and photoluminescent spectroscopy. Moreover, nitrogen adsorption−desorption measurement, electrochemical and photocatalysis properties for degradation of methylene blue (MB) upon a UV irradiation of compound 1 have been examined. [ABSTRACT FROM AUTHOR]

This paper reports the first systemic investigation on the bimetallic ring coordination polymers based on two structure-related flexible bis(imidazole) ligands, bimb as well as bix [bimb = 1, 4-bis(imidazol-1-yl)-butane, bix = 1, 4-bis(imidazol-1-yl-methylene)-benzene)]. As expected, six new cobalt complexes were generated, namely, [Co2(SCN)4(bimb)2] ( 1), [Co2(L1)2(bimb)2Cl2] ( 2), [Co2(L2)4(bix)2] ( 3), [Co(SCN)2(bimb)2] ( 4), {Co[N(CN)2]2(bimb)2} ( 5), and [Co(L3)(bix)] ( 6) (HL1 = 4-aminobenzoic acid, HL2 = 4-nitrobenzoic acid, and H2L3 = succinic acid). The structures of 1- 3 are three discrete dinuclear ring motifs. Especially, 1 is the first example of 1D pseudo-polyrotaxane formed by S ···S strong interactions based on bis(imidazole) ligands. 4 and 5 exhibit 1D meso-helical chain architecture, in spite of their different space groups. In 6, the discrete dinuclear ring motifs, traversed by μ2-η3-chelating L3 anions, are interconnected by another μ2-η1-bridging L3 anions to form 2D (4, 4) network. The formation of these compounds should be undoubtedly attributed to the preference for cis-bis(imidazole) ligands crystallization resulting in various ring architectures. In addition, compound 6 exhibits antiferromagnetic behavior. [ABSTRACT FROM AUTHOR]

Inorganic-organic hybrid compound (C 3 H 5 N 2 ) 2 (H 2 O){[Li(H 2 O)][Co(CN) 6 ]} was synthesized by the reaction of Li 3 [Co(CN) 6 ] with imidazolium chloride in aqueous solution. It crystallizes in the chiral orthorhombic space group P 2 1 2 1 2 1 at 293 K. The anionic chiral 3D structure is composed of helical chains based on the inorganic {[Li(H 2 O)][Co(CN) 6 ]} building blocks. Imidazolium cations and crystallization water molecules reside in the voids of the anionic framework through rich hydrogen bonds. [ABSTRACT FROM AUTHOR]