Synthesis and characterisation of main-chain hydrogen-bonded supramolecular liquid crystalline complexes formed by azo-containing compounds

A series of azopyridine-containing hydrogen bonding acceptors (4a-c) with flexible spacers of oligo(methylene) were synthesised. Hydrogen-bonded polymeric complexes 4/5 and trimeric complexes 4/6₂ , where 5 and 6 are aromatic dicarboxylic acids and monocarboxylic acids, respectively, were prepared and their liquid crystallinity was examined using differential scanning calorimetry and polarising optical microscopy. The study showed that most of the complexes displayed reversible thermotropic nematic phase. The isotropic to nematic phase transition temperatures of polymeric complexes 4/5 and trimeric complexes 4/6₂ in general decreased with the increase in length of spacers and terminal groups in the corresponding proton acceptors 4 and the proton donors 5 and 6, respectively. Hydrogen bonding interactions in complexes 4/5 and 4/6₂ were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.     

两种双核稀土配合物的光致变色和光磁效应

利用光诱导电子转移机理和配位驱动组装策略探索室温光磁效应材料的合成. 通过组装稀土硝酸盐与1,10-菲罗啉(phen)获得2种同构双核稀土配合物[Ln₂(NO₃)₆(phen)₂](1: Ln=Gd; 2: Ln=Dy). 由于具有电子给体-受体结构特征, 目标产物在光照后发生电子转移, 电子由硝酸根的氧原子转移到phen的氮原子, 进而产生光生自由基并发生肉眼可见的颜色变化. 除光致变色外, 配合物1和2在室温下具有光磁效应. 本研究为构筑室温光致变色和光磁效应杂化材料提供了一种通用方法: 配位组装顺磁金属盐与菲罗啉衍生物.     

The first case of a lyotropic twisted nematic (N*) phase induced by a chiral charge transfer complex [1]

The disc-shaped tetra-palladium organyl 1 forms optically active charge transfer complexes in equimolar mixtures with the enantiomers of the π-acid electron acceptor 2, (+)- or (-)-TAPA, exhibiting lyotropic cholesteric nematic properties in apolar organic solvents. These ternary systems are the first examples in which such a lyomesophase has been induced by charge transfer interactions.     

Induction of nematic cholesteric (N*) phases by charge transfer complexation of disc-shaped multiynes [1]

Based on charge transfer interactions with the (chiral) electron acceptor (-)-2-(2,4,5,7-tetranitro-9-fluorenylidenaminooxy)propionic acid ((-)-TAPA), our easily accessible disc-shaped electron rich multiynes (for example, 1 and 2) give rise to two types of cholesteric nematic phases. Thus, the binary mixture of the nematic discotic (N_D) pentakis-(4-methylphenylethynyl)phenyl hexadecyl ether (2) with (-)-TAPA exhibits its twisted variant (N*_D). Likewise, but now in a ternary mixture, the homologue 1—peripherically unsubstituted and non-mesogenic—with the two electron acceptors (-)- TAPA and 2,4,7-trinitrofluorenone—both also non-liquid crystalline—shows cholesteric nematic properties, most probably however of a columnar type (N*_C). First results concerning these charge transfer induced cholesteric-nematic properties, including phase diagrams and the helical twist of the two systems presented here, are discussed on the basis of data obtained by polarizing microscopy and differential scanning calorimetry.     

A simple strategy for constructing acylhydrazone photochromic system with visible color/emission change and its application in photo-patterning

As a potential photochromic system, acylhydrazones exhibit many outstanding advantages including low cost, simple synthesis and high modifiability compared with some classic photochromic systems. However, the absorptionwavelengths of acylhydrazones usually locate in ultraviolet region, which makes the band separation between the absorbance maxima of its irradiated and unirradiated forms cannot be observed by naked eyes and greatly limits their practical applications. In this work, a simple strategy for constructing acylhydrazone photochromic system with visible color/emission change is provided. Rhodamine 6G hydrazine-2-aldehyde-pyridine Schiff base (compound 3) is designed and synthesized by combining acylhydrazone with Rhodamine 6G structure. The introduction of Rhodamine 6G moiety to 3 not only makes it remain all the advantages of acylhydrazone photochromic system but also exhibits visible photo-induced color/emission changes both in solution and in a solid matrix. Moreover, 3 exhibits reversible photochromic property with good fatigue resistance, which makes it an excellent candidate for photo-patterning.     

Paramagnetic features of the molecular complexes of poly (phenylacetylene)

The complexes of poly(phenylacetylene) (PPA) with electron acceptors are examined. The concentration of paramagnetic centers is estimated, together with the line-shape parameters and the size of the delocalization region. The temperature dependence of the ESR intensity is used to show that the paramagnetism of complexes of PPA with weak acceptors is due solely to the formation of local defect centers. PPA forms strong charge-transfer complexes with iodine, tetracyanoethylene, and tetracyanoquinodimethane; these contain ion radicals. The activation energy for charge transfer in these complexes is 0.12–0.14 eV. An ESR signal has also been observed from the complex of PPA with the electron donor naphthacene.     

Synthesis ofα-D-GlcpNAc-（1→2）-[α-D-ManpNAc-（1→3）-]α-L-Rhap-（1→2）-α-L-Rhap-（1→3）-α-L-Rhap,the repeating unit of O10 antigen from Acinetobacter baumannii

An efficient synthesis ofα-D-GlcpNAc-（1→2）-[α-D-ManpNAc-（1→3）-]α-L-Rhap-（1→2）-α-L-Rhap-（1→3）-α-L-Rhap（1）, the repeating unit of the O10 antigen from Acinetobacter baumannii was achieved via sequential assembly of the building blocks,p- methoxylphenyl 2,4-di-O-benzoyl-α-L-rhamnopyranoside（2）;2-O-allyloxycarbonyl-3,4-di-O-bcnzoyl-α-L-rhamnopyranosyl tri- chloroacetimidate（3）;4-methoxylphenyl 3-O-allyloxycarbonyl-4-O-benzoyl-α-L-rhanmopyranoside（4）;2-azido-3-O-benzoyl-2- deoxy-4,6-O-isopropylidene-α-D-mannopyranosyl trichloroacetirnidatc（5）;2-azido-3,4,6-tri-O-benzoyl-2-deoxy-α,β-D-glucopyr- ano syl trichloroacetimidatc（6）.The total yield of 1 from 4 was 4.7%.     

Polyoxygenated anti-inflammatory biscembranoids from the soft coral Sarcophyton tortuosum and their stereochemistry

Five novel biscembranoids,ximaolides H-L(1-5),along with four known related compounds(6-9) were isolated from the Hainan soft coral Sarcophyton tortuosum.The structures of the new compounds were determined by extensive spectroscopic analysis,quantum chemical calculations,and/or by comparing their CD spectra with those of the known compounds.Compounds 1 and 2 are the first examples of biscembranoids bearing a 1,35-bridged lactone moiety,4 is the first biscembranoid comprising an uncommon oxetane ring,and 5 represents the first 36-peroxyl biscembranoid.Ximaolides Ⅰ(2),K(4) and F(9) exhibited interesting anti-inflammatory activity by the inhibition of LPS-induced TNF-α protein release in RAW264.7 macrophages.     

Two Zinc(Ⅱ) Complexes Based on 7rany-(1R,2R)-cyclohexanediamine: Molecular Structure Analyses and Preparation of Composite Membrane

Two novel complexes Zn2(chda)2(TPA)Cl2(1) and [Zn(chda)2(H2O)2](TPAXH2O)2(2)[chda is a chiral ligand of trans-(1R,2R)-cyclohexanediamine, H2TPA is terephthalic acid] were synthesized at room temperature. The molecular structures of complexes 1 and 2 were identified by single-crystal X-ray diffraction measurement. The results showed that complex 1 had a binuclear structure, each Zn(Ⅱ) ion was four coordinated by two N atoms of chda, one O atom of TPA and one Cl atom, to construct a distorted tetrahedral geometry. For complex 2, the Zn(Ⅱ) ion was six coordinated by two chda molecules and two water molecules to form a ZnN4O2 octahedral geometry. Complexes 1 and 2 further extended into three-dimensional supramolecular frameworks by hydrogen-bonding interactions. Hirshfeld surface analysis and fingerprint plots were used to further analyze the contribution of diflerent intermolecular interactions. Further, a composite membrane [Zn(chda)2(H2O)2](TPA)(H2O)2/CA was prepared by adding 10%(mass fraction) of complex 2 into cellulose acetate using acetone/chloroform( V:V-1:1) as solvent.     

Photochromism of metal complexes composed of diarylethene ligands and Zn(II), Mn(II), and Cu(II) hexafluoroacetylacetonates

Metal complexes composed of bidentate 1,2-bis(2-methyl-5-(4-pyridyl)-3-thienyl)perfluorocyclopentene (1a) and monodentate 1-(2-methyl-5-phenyl-3-thienyl)-2-(2-methyl-5-(4-pyridyl)-3-thienyl)perfluorocyclopentene (2a) photochromic ligands and M(hfac)(2) (M = Zn(II), Mn(II), and Cu(II)) were prepared, and their photoinduced coordination structural changes were studied. X-ray crystallographic analyses showed the formation of coordination polymers and discrete 1:2 complexes for bidentate and monodentate ligands, respectively. The complexes underwent reversible photochromic reactions by alternate irradiation with UV and visible lights in solution as well as in the single-crystalline phase. Upon photoirradiation with UV and visible light, the ESR spectra of the copper complexes of 1a reversibly changed. While the open-ring isomer gave an axial-type spectrum, the photogenerated closed-ring isomer showed a rhombic-type spectrum. This indicates that the photoisomerization induced the change in the coordination structure.     

Liquid crystalline properties of dissymmetric molecules VI. The effect of alkyl chain length on molecular arrangement in the smectic A phase in three-aromatic-ring systems with two ester groups

The effect of alkyl and alkoxy chain lengths on the layer structures of smectic A and C phases has been examined by X-ray diffraction measurements on three isomeric systems: 4-alkoxyphenyl and 4-n-alkylphenyl 4-[(4-octyloxyphenyl)carbonyloxy]benzoates (1); 4-octyloxyphenyl 4-[4-(octyloxyphenyl)carbonyloxy]benzoates (2); 4-octyloxyphenyl, 4-alkoxyphenyl and 4-n-alkylphenyl terephthalates (3); and p-phenylene 4-octyloxybenzoates, 4-alkoxybenzoate and 4-n-alkylbenzoate (4). Although all the derivatives exhibit smectic A and/or C phases having a monolayer arrangement of the molecules, the layer spacings are considerably affected by alternation of the ester linkages. The layer spacings for the homologues of 1 are a little shorter than the calculated molecular lengths, while those for 2 agree with the calculated molecular lengths. The layer spacings for 3 show a notable even-odd alternation in the higher homologues. The results are discussed in terms of a subtle change in the molecular structures due to replacement of the ester groups.     

In situ[2 + 3] cycloaddition synthesis,crystal structures,strong SHG responses and fluorescence properties of three novel Zn coordination polymers

We report on the synthesis of two acentric and one centrosymmetric Zn metal-organic complexes with 3-tetrazolenethyl pyridine spacers obtained in situ by hydrothermal routes.X-ray diffraction structural analysis reveals that they have the same equivalent nodes but with dissimilar topologies.The two acentric frameworks[Zn(Tzmp)Cl]n(1)and([Zn(Tzmp)Br]n(2),HTzmp=3-tetrazolemethyl pyridine)are isomorphism which exhibit an acentric 3D framework with(10,3)-b net called"ths",while the centro symmetric complex([Zn(Tzmp)N3]n(3))features a distinctive 2D sheet with Shubnikov hexagonal plane net.Photo-luminescent studies suggest the ligand-field strength of coordinated negative ions(Cl^->Br^->N3^-)has ordered adjusting effects on the emission redshift.The second harmonic generation(SHG)measurement shows that compounds 1 and 2 are nonlinear optically active,with SHG responses being 2/3 and half of the standard potassium dihvdrogen phosphate(KDP),respectively.     

A novel cytotoxic neophysalin from Physalis alkekengi var.francheti

A new neophysalin,named 5α-hydroxy-25,27-dihydro-4,7-didehydro-7-deoxyneophysalin A(1),along with three other known neophysalins(2-4) were isolated from the calyxes of Physalis alkekengi L.var.francheti(Mast.) Makino.The structure of 1 was determined by means of 1D and 2D NMR,UV,IR and mass spectra.Compound 1 displayed potent cytotoxicities in vitro against PC- 3 and LNCaP cell lines.     

Two New Borates Built by Different Types of {B9} Cluster Units

Two new belt-like borates Na₄[B₉O₁₄(OH)₃]·0.5H₂O(1) and Na₅[B₉O₁₄(OH)₄](2) have been synthesized under solvothermal conditions. Both compounds contain unprecedented B₉O₁₆(OH)_n^(n+5)-[n=3(1), 4(2)] clusters, which are constructed from four B₃O₃ rings via three BO₄ tetrahedra. Compound 1 exhibits a rare 1D belt with two types of 8-membered ring(MR) windows based on B₉O₁₆(OH)₃^8- clusters. Compound 2 features two different 1D belts built by different B₉O₁₆(OH)₄^9- units, which is first discovered in borate family. UV-Vis diffuse reflectance spectra reveal that compounds 1 and 2 have the cut-off edges below 190 nm, indicating that they may have potential application in deep UV(DUV) region.     

On the thermal behaviour of palladium (II) macrocyclic polycatenars

Polycatenar saturated macrocycles 1,10-bis[3,4,5-tris(4-dodecyloxy)benzoy1]-1,10-diaza-4,7,13,16-tetrathiacyclo-octadecane (3b) and 1,10-bis[3,4-bis(4-dodecyloxy)benzoy1] -1,10-diaza-4,7,13,16-tetrathiacyclo-octadecane (3d) reacted with [Pd(MeCN)₄][BF₄]₂ led to the cationic complexes [4b][BF₄]₂ and [4d][BF₄]₂, respectively. Complexes [4b][BF₄]₂ and [4d][BF₄]₂ showed smectic mesomorphism on heating as confirmed by small angle X-ray diffraction. A concurrent, irreversible structural change of the complex cations was observed and a tentative explanation is suggested.     

STUDIES ON THE SYNTHESIS OF RABDOSIA DITERPENOID Ⅱ, PREPARATION OF A KEY BUILDING BLOCK, α, β-UNSATURATED LACTONE

The main half molecule (4a) of the trichorabdal B (1) was synthesized from pentadienol (6).The key step is the intramolecular Diels-Alder reaction of 8.     

Lyotropic phase behaviour of disc-shaped tetra-palladium organyls in apolar organic solvents [1]

The lyomesomorphic behaviour in apolar organic solvents of members of two series 1 and 2 of disc-shaped palladium organyls—the syntheses of four of them are new (1d, f and 2a, e) and are described here—each carrying twelve long lipophilic chains have been studied. Their lyomesomorphism appeared to be complex and has been observed here for the first time with metal organyls. As can be seen by polarizing microscopy, most of the binary mixtures investigated here exhibit nematic properties. For two members of series 1—the chloro-bridged 1b and its bromo-analogue 1c—there is even evidence for the existence of two different nematic lyomesophases side by side showing reversible transitions between them. In ternary systems, i.e. after the addition of 2,4,7-trinitrofluorenone (TNF, a strong electron acceptor), the nematic phases are stabilized, suggesting that their mesophase structures are made up by columns with intercalated TNF molecules (charge transfer complex formation). Influences of structural features of the pallado-mesogens on the one hand and of the type of solvent on the other on the molecular self-aggregation in the observed types of lyotropic mesophase formed are discussed in detail.     

Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru(II) tris-bipyridine: an approach to mimics of the donor side of photosystem II

To mimic the electron-donor side of photosystem II (PSII), three trinuclear ruthenium complexes (2, 2a, 2b) were synthesized. In these complexes, a mixed-valent dinuclear Ru2(II,III) moiety with one phenoxy and two acetato bridges is covalently linked to a Ru(II) tris-bipyridine photosensitizer. The properties and photoinduced electron/energy transfer of these complexes were studied. The results show that the Ru2(II,III) moieties in the complexes readily undergo reversible one-electron reduction and one-electron oxidation to give the Ru2(II,III) and Ru2(III,III) states, respectively. This could allow for photooxidation of the sensitizer part with an external acceptor and subsequent electron transfer from the dinuclear ruthenium moiety to regenerate the sensitizer. However, all trinuclear ruthenium complexes have a very short excited-state lifetime, in the range of a few nanoseconds to less than 100 ps. Studies by femtosecond time-resolved techniques suggest that a mixture of intramolecular energy and electron transfer between the dinuclear ruthenium moiety and the excited [Ru(bpy)3]2+ photosensitizer is responsible for the short lifetimes. This problem is overcome by anchoring the complexes with ester- or carboxyl-substituted bipyridine ligands (2a, 2b) to nanocrystalline TiO2, and the desired electron transfer from the excited state of the [Ru(bpy)3]2+ moiety to the conduction band of TiO2 followed by intramolecular electron transfer from the dinuclear Ru2(II,III) moiety to photogenerated Ru(III) was observed. The resulting long-lived Ru2(III,III) state decays on the millisecond timescale.     

N-芳基马来酰亚胺与硫代硫酸钠的电荷转移络合物研究

本文以硫代硫酸根离子作为电荷给体(D),系列N-芳基取代马来酰亚胺(RPhMI)作为电荷受体(A),用含水5%的二甲基亚砜(95%DMSO)为溶剂,以紫外可见分光光度法研究了RPhMI与S₂O₃^2-作用生成的电荷转移(CT)络合物。以其CT光谱计算了RPhMI的电子亲合能(E_A).测定了CT络合物的生成常数K.结果显示,弱的受体N-马来酰亚胺与强的给体硫代硫酸根负离子可以生成稳定的CT络合物。文章还讨论了CT络合物的可能结构及取代基极性与CT络合物的稳定性关系。