- Bimodal Heterogeneous Functionality in Redox-Active Conjugated Microporous Polymer toward Electrocatalytic Oxygen Reduction and Photocatalytic Hydrogen Evolution
-
The designing and development of heterogeneous catalysts for conversion of renewable energy to chemical energies by electrochemical as well as photochemical processes is at the forefront of energy research. In this work, two new donor–acceptor-based redox-active conjugated microporous polymers (CMPs) (TAPA-OPE-mix and TAPA-OPE-gly) are synthesized through Schiff base condensation reaction using a microwave synthesizer. Notably, the asymmetric and symmetric bola-amphiphilic nature of the OPE struts results in distinct nanostructuring and morphologies in the CMPs. Interestingly, both CMPs show impressive heterogeneous catalytic activity toward electrochemical O2 reduction and photocatalytic H2 evolution reactions, and therefore, act as bimodal electro- and photocatalytic porous organic materials. Furthermore, the redox-active property of the CMPs is exploited for in situ generation and stabilization of platinum nanoparticles (Pt), and these Pt@CMPs exhibit significantly enhanced photocatalytic activity.
- Singh, Ashish,Verma, Parul,Samanta, Debabrata,Singh, Tarandeep,Maji, Tapas Kumar
-
-
Read Online
- Phase transition in cyclic organophosphazenes: The effect of side chains on mesomorphism
-
Mesogenicity of five cyclotriphosphazenes and two cyclotetraphosphazenes with a similar dodecyl or dodecyloxy end and different central hard groups was studied. In the four cyclotriphosphazenes except for a cyclotriphosphazene with phenyl derivative side chains, enantiotropic mesomorphic phases were observed. The order of the thermal stability in mesophase is phenylazobenzene > phenyliminomethylphenyl > biphenyl groups for the side chains. The cyclotetraphosphazenes with biphenyl and Schiff base derivatives have lower mesomorphic thermal stability than cyclotriphosphazenes with the same side groups.
- Moriya, Keiichi,Yamane, Toshihiro,Suzuki, Toshiya,Kajiwara, Meisetsu,Yano, Shinichi
-
-
Read Online
- Nonplanar Ladder-Type Polycyclic Conjugated Molecules: Structures and Solid-State Properties
-
Using an efficient intramolecular carbon-carbon cross-coupling reaction, a series of new ladder-type conjugated molecules have been prepared successfully in high yields. Such a pyran-fused polycylic structure possesses an extended π-conjugated backbone with flexible conformation, which gives these molecules interesting properties, including high solubility in common organic solvents, excellent thin film-forming abilities, blue fluorescent emission with good quantum yields, and aggregate formation in a binary solvent. The self-assembly behaviors of these molecules as well as various nanostructures can be finely tailored by varying the substituted group on the molecular periphery. The powder and single-crystal X-ray diffraction analyses revealed that the synergetic effect of π-π stacking and van der Waals interactions play a key role in controlling the morphologies of these aggregates. More importantly, self-assembled molecules exhibit good fluorescent performance, due to their twist backbone conformation. (Figure Presented).
- Liu, Kuojin,Qiu, Feng,Yang, Chongqing,Tang, Ruizhi,Fu, Yubin,Han, Sheng,Zhuang, Xiaodong,Mai, Yiyong,Zhang, Fan,Feng, Xinliang
-
-
Read Online
- New phosphorescent platinum(ii) complexes with tetradentate C*N^N*C ligands: liquid crystallinity and polarized emission
-
New phosphorescent, liquid crystalline cyclometalated tetradentate platinum complexes (Pt-L16, Pt-L12 and Pt-L6) based on the tetradentate C*N^N*C ligands (C*N^N*C = 6,6′-bis(4-(alkoxy)-phenoxy)-2,2′-bipyridine) are designed and synthesized. Their crystal structure, and photophysical, electrochemical and liquid crystal characteristics were investigated. The X-ray structure of Pt-L12 shows a severe distortion of this complex towards a tetrahedral geometry. All complexes are emissive both in degassed solution and in the solid state at room temperature with emission maxima in the red region of the spectrum. Pt-L16 and Pt-L12 show monotropic smectic liquid crystal characteristics. Moreover, these liquid crystal complexes can be aligned on a rubbed nylon-6 glass substrate and produce polarized emission with a dichroic ratio of 5.1.
- Zhang, Shilin,Luo, Kaijun,Geng, Hao,Ni, Hailiang,Wang, Haifeng,Li, Quan
-
-
Read Online
- Polymer Composition
-
Methods for forming a laminate are provided. The method provides a highly aligned block copolymer without orientation defects, coordination number defects distance defects and the like on a substrate, thereby providing a laminate which can be effectively
- -
-
Paragraph 0221-0226
(2020/12/01)
-
- Compound and use thereof
-
[A] a method of sufficiently exhibiting the monomolecular film. (1) A compound represented by the general formula [a] is. (1) A e B e C a-L(In the formula, and the A C, respectively, and/or heteroatom ring structure may be of straight-chain hydrocarbon gr
- -
-
Paragraph 0056; 0057
(2019/05/22)
-
- Photoswitchable J-aggregated processable organogel by integrating a photochromic acceptor
-
A novel αchromophoric 1,4-bis(anthracenylethynyl)benzene (BAB)-based highly emissive J-aggregated organogel has been synthesized and characterized. Single-crystal structure determination of asymmetric π-chromophoric bola-amphiphilic BAB1 (dodecyl and triethyleneglycolmonomethylether containing side chains of bis(anthracenylethynyl)benzene) supports J-aggregation. Further, a photochromic acceptor chromophore, 4,4′-(perfluorocyclopent-1-ene-1,2-diyl)bis(5-methylthiophene-2-carbaldehyde), is noncovalently encapsulated in the gel and photoswitching studies have been performed based on photochromic F?rster resonance energy transfer. The modulated emission of the processable soft material is further exploited for rewritable display. However, BAB2 (dodecyl side chain on both sides) does not show gelation property due to its low solubility.
- Samanta, Debabrata,Singh, Ashish,Verma, Parul,Bhattacharyya, Sohini,Roy, Syamantak,Maji, Tapas Kumar
-
supporting information
p. 10946 - 10952
(2019/09/30)
-
- Solvent Adaptive Dynamic Metal-Organic Soft Hybrid for Imaging and Biological Delivery
-
A solvent responsive dynamic nanoscale metal-organic framework (NMOF) [Zn(1 a)(H2O)2] has been devised based on the self-assembly of ZnII and asymmetric bola-amphiphilic oligo-(p-phenyleneethynylene) (OPE) dicarboxylate linker 1 a having dodecyl and triethyleneglycolmonomethylether (TEG, polar) side chains. In THF solvent, NMOF showed nanovesicular morphology (NMOF-1) with surface decorated dodecyl chains. In water and methanol, NMOF exhibited inverse-nanovesicle (NMOF-2) and nanoscroll (NMOF-3) morphology, respectively, with surface projected TEG chains. The pre-formed NMOFs also unveiled reversible solvent responsive transformation of different morphologies. The flexible NMOF showed cyan emission and no cytotoxicity, allowing live cell imaging. Cisplatin (14.4 wt %) and doxorubicin (4.1 wt %) were encapsulated in NMOF-1 by non-covalent interactions and, in vitro and in vivo drug release was studied. The drug loaded NMOFs exhibited micromolar cytotoxicity.
- Samanta, Debabrata,Roy, Syamantak,Sasmal, Ranjan,Saha, Nilanjana Das,Pradeep,Viswanatha, Ranjani,Agasti, Sarit S.,Maji, Tapas Kumar
-
supporting information
p. 5008 - 5012
(2019/03/11)
-
- Flavylium Salts: A Blooming Core for Bioinspired Ionic Liquid Crystals
-
Thermotropic ionic liquid crystals based on the flavylium scaffold have been synthesized and studied for their structure-properties relationship for the first time. The mesogens were probed by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD). Low numbers of alkoxy side chains resulted in smectic (SmA) and lamello-columnar (LamCol) phases, whereas higher substituted flavylium salts showed Colro as well as ordered and disordered columnar (Colho, Colhd) mesophases. Mesophase width ranged from 13 K to 220 K, giving access to room temperature liquid crystals. The optical properties of the synthesized compounds were probed towards absorption and emission properties. Strong absorption with maxima between 444 and 507 nm was observed, and some chromophores were highly emissive with quantum yields up to 99 %. Ultimately, mesogenic and dye properties were examined by temperature-dependent emissive experiments in the solid state.
- Forschner, Robert,Knelles, Jakob,Bader, Korinna,Müller, Carsten,Frey, Wolfgang,K?hn, Andreas,Molard, Yann,Giesselmann, Frank,Laschat, Sabine
-
p. 12966 - 12980
(2019/11/05)
-
- Pure white light emission and charge transfer in organogels of symmetrical and unsymmetrical π-chromophoric oligo-: P -(phenyleneethynylene) bola-amphiphiles
-
Two novel bola-amphiphilic oligo-p-(phenyleneethynylene) (OPE) dicarboxylates have been synthesized having non-polar and mixed-polar side chains. This led to gelation in both with vesicular morphology. Upon in situ loading of a suitable dye and redox-active molecule, pure white light emitting and charge transfer (CT)-gels, respectively, were realized.
- Roy, Syamantak,Samanta, Debabrata,Kumar, Pramod,Maji, Tapas Kumar
-
p. 275 - 278
(2018/01/12)
-
- METHOD OF PURIFYING ALKOXYPHENOL
-
PROBLEM TO BE SOLVED: To provide a purifying method that can easily remove a dialkoxybenzene from a crude composition containing an alkoxyphenol, to obtain a high-purity alkoxyphenol, and a production method that allows a high-purity alkoxyphenol to be obtained. SOLUTION: After a C1-5 lower alcohol is added to a crude composition containing an alkoxyphenol, represented by formula (1), and insoluble matter is subjected to solid-liquid separation (where R is a C6-20 alkyl group). SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
- -
-
Paragraph 0055; 0056
(2018/01/11)
-
- Intramolecular charge transfer interactions and molecular order of rod like mesogens
-
A mesogenic 4-((4-(alkoxy)phenoxy)carbonyl)phenyl-4-(dimethylamino)benzoate series with terminal chains varying from C2 to C12 carbons (even number carbons only) are synthesised and their mesophase transitions are examined by hot-stage optical polarising microscopy as well as differential scanning calorimetry. Accordingly, enantiotropic nematic mesophase for all the homologs and an additional smectic A phase for the C12 homolog is observed. Powder X-ray diffraction studies confirm the interdigitated bilayer organization in the smectic A phase for the C12 homolog. It is remarkable that the mesogens under investigation only differ in the linking unit i.e. ester versus imine in contrast to recently reported mesogens, yet show a large difference in certain properties. Accordingly, the crystal structure of the C4 homolog reveals a triclinic lattice with P1 space group in which the molecules are packed in a slipped co-facial configuration. Additionally, a detailed investigation of the C12 mesogen by UV-visible and fluorescence spectroscopy as well as computational methods unveils interesting features. The fluorescence spectrum of the C12 mesogen is observed at 366 nm with a shoulder at 433 nm and a large solvent polarity induced red-shift is noticed in contrast to a structurally similar homolog examined recently. Further, the C12 mesogen in solvents such as ethyl acetate, dichloromethane, chloroform, tetrahydrofuran, acetonitrile and dimethyl sulfoxide exhibited dual emission. Therefore, density functional theory and time dependent density functional theory calculations are utilized to obtain insight. Besides variation in the dihedral angle between rings B and C for the C12 mesogen, it is found that the highest occupied molecular orbital (HOMO) is localized on the N,N-dimethylaminobenzene moiety while the lowest unoccupied molecular orbital (LUMO) is mostly concentrated on the phenyl benzoate unit. Time dependent-density functional theory (TD-DFT) calculations disclose the orbitals involved in the dominant excited state electronic transitions and their corresponding energies together with oscillator strength. The high resolution 1D and 2D separated local field (SLF) solid state 13C NMR investigation of the C12 mesogen lead to the orientational order parameters of the phenyl rings of the core in the SmAd phase. The temperature versus alignment induced chemical shifts reveals an increase in chemical shifts with a decrease in temperature in the smectic Ad phase in concurrence with order parameter values. Thus, understanding the photophysical properties of mesogens with dimethylamino moieties would facilitate better design of molecules for application in organic light emitting diodes for polarized emission.
- Reddy, M. Guruprasad,Lobo, Nitin P.,Varathan,Easwaramoorthi,Narasimhaswamy
-
p. 105066 - 105078
(2015/12/30)
-
- Synthesis and liquid crystal property of new fluoro coumarin carboxylates
-
New liquid crystalline 4-alkoxyphenyl-coumarin-3-carboxylates 6a-e, 7a-g, 8a-e, and 9a-e were prepared by reacting various coumarin-3-carboxylic acids 5a-d with 4-(alkoxy) phenols 4a-g in the presence of 1(3-dimethylaminopropyl-3- ethylcarbodiimide/dimethyl amino pyridine (EDCI/DMAP) as a coupling agent. The structures of the new coumarin derivatives were confirmed by spectral analysis and the liquid crystalline property was established by polarizing optical microscope and by differential scanning calorimetric techniques. The diethyl amine and morpholine were taken as electron-donating and -CF3 as electron-withdrawing groups at the seventh position of the coumarin-3-carboxylic acids to check the mesomorphic property in all new 4-alkoxyphenyl-coumarin-3- carboxylates. Among them, only 4-alkoxyphenyl-7-triflouromethyl-coumarin-3- carboxylates 7a-g exhibited liquid crystalline SmA phase.
- Mahadevan, Kittappa M.,Harishkumar, Hosanagara N.,Masagalli, Jagadeesh N.,Srinivasa, Hosapalya T.
-
-
- Synthesis, surface tension properties and antibacterial activities of amphiphilic d-galactopyranose derivatives
-
Several amphiphilic d-galactopyranose derivatives were synthesized in which the glycosidic moiety was separated from the hydrophobic alkyl chain (along 8 or 12 carbon atoms) by a spacer arm (butyl, butynyl or benzyl) in order to increase their surfactant properties and to obtain new antibacterial compounds. The surface tensions of the products were analyzed by Critical Micelle Concentration (CMC) and γCMC measurements and the antimicrobial activities were assayed against 10 bacterial species by Minimum Inhibitory Concentration (MIC) determination in liquid broth. The introduction of an aliphatic spacer arm increased the amphiphilic properties of the compounds and the CMC values were 40-500 times lower than their analogs without spacer arm. In the same manner, the spacer arms significantly increased the antibacterial power of the compounds. The products 4d and 4e exhibiting a C12 alkyl chain and an aliphatic spacer arm (butyl and butynyl) were the best surfactants (CMC = 0.023 and 0.032 mmol/L, respectively) and presented also the best antibacterial activities (MIC = 15.62 and 3.91 μg/mL for Micrococcus luteus, respectively). But the antibacterial activity of the newly synthesized products seemed to depend more on the cell wall composition of the bacteria than only on the amphiphilic character of the compounds.
- Chaveriat, Ludovic,Gosselin, Isabelle,Machut, Cecile,Martin, Patrick
-
p. 177 - 186
(2013/06/04)
-
- Novel macro metallomesogens derived from simple dihydroxy benzenes
-
A series of tetradentate Schiff base metallomesogenic diols and their model compounds were synthesized from two simple dihydroxy benzenes. The metallomesogenic diol was constructed from three ring containing mesogen linked through ester and azomethine with terminal hydroxy group. This upon complexation with copper(II) formed metallomesogenic diol with varing terminal chain length. The related model metallomesogenic compounds were also synthesized with varying chain length with terminal methyl group and compared the properties with metallomesogenic diols. Extensive characterization of all metallomesogenic compounds and intermediates were carried out by FT-IR, 1H & 13C NMR, EPR, VSM, Mass (EI and FAB) and UV-Vis spectroscopy. Hot stage polarizing microscope, Differential scanning calorimetry was used to ensure the phase characteristics such as nature of phase, melting and clearing temperatures and phase range. The appearance of enantiotropic smectic A phases indicated high molecular polarizability of the core due to the metal ion. The role of copper(II) ion on mesogens were discussed.
- Senthilkumar, Natarajan,Raghavan, Aravamudhan,Narasimhaswamy, Tanneru,Kim, Il-Jin
-
p. 129 - 139
(2013/06/04)
-
- Side-chain liquid-crystalline polymers based on flexible rod-like mesogen directly attached to backbone
-
In this article, we report the synthesis and characterization of a new end-on side-chain liquid crystalline polymer (SCLCP), poly[4-(4′- alkoxyphenyloxymethylene)styrene] [denoted as Poly(n-POMS), where n is the carbon number of the alkyl tail, n = 2, 4, 6, 8, 12, 16], with the flexible rod-like mesogenic side-chain directly attached to the polymer backbone without flexible spacer. The polymer was obtained by using free radical polymerization. The chemical structures of Poly(n-POMS) and the corresponding monomer were characterized using various techniques with satisfactory analysis data. A combination analysis of differential scanning calorimetry, polarized light microscopy, small angle X-ray scattering, and wide-angle X-ray diffraction has been conducted to investigate the phase behavior of Poly(n-POMS). Poly(2-POMS), Poly(4-POMS), and Poly(6-POMS) are amorphous. Poly(8-POMS) develops partially into the liquid crystal phase, and Poly(12-POMS) and Poly(16-POMS) self-assembly into the smectic A (SmA) phase. Upon increasing temperature, the phase transition of Poly(16-POMS) follows the sequence of SmA1 ? SmA2 ? isotropic (I), which may be attributed to the conformation isomerization of the flexible rod-like mesogens.
- Zheng, Jun-Feng,Yu, Zhen-Qiang,Liu, Xin,Chen, Xiao-Fang,Yang, Shuang,Chen, Er-Qiang
-
p. 5023 - 5031
(2013/01/15)
-
- Synthesis and optical/thermal behavior of new Azo photoisomerizable discotic liquid crystals
-
In this study, discotic azo compounds were prepared by a reductive coupling of 5-nitroisophthalic acid followed by a convergent synthesis, resulting in five new examples of azo photoisomerizable discotic molecules, which differ from each other by the link
- Westphal, Eduard,Bechtold, Ivan H.,Gallardo, Hugo
-
experimental part
p. 1319 - 1328
(2011/10/02)
-
- Novel hydroxy- and methyl-terminated triaromatic schiff base compounds: Synthesis and mesogenic properties
-
A series of Schiff base hydroxy-mesogens and their model compounds have been synthesized. The mesogen is constructed from three-ring-containing mesogens linked through ester and azomethine groups with a terminal hydroxy group. The related model compounds were also synthesized with varying chain length with a terminal methyl group and their properties were compared with that of hydroxy mesogens. Extensive characterization of all mesogenic compounds was carried out by Fourier-transform IR, 1H and 13C NMR and mass spectroscopy. The phase characteristics such as nature of phase, melting and clearing temperatures and phase range were evaluated using a hot-stage optical polarizing microscope and differential scanning calorimetry. The appearance of enantiotropic smectic phases is due to the high molecular polarizability of the triaromatic core with azomethine and ester linkages. CSIRO 2010.
- Senthilkumar, Natarajan,Narasimhaswamy, Tanneru,Raghavan, Aravamudhan
-
experimental part
p. 276 - 285
(2011/06/19)
-
- Hydrogen-bond induced side-chain liquid crystalline polymers based on nicotinic acid derivatives
-
Supramolecular side-chain liquid crystalline poly(acrylate)s have been prepared by self-assembly of H-bond donor and acceptor complexes through intermolecular complementary hydrogen bond formation. Poly[4-(m-acryloyloxyalkyloxy)benzoic acid]s [m = 6 (P1) and 8 (P2)] were employed as polymer components. Liquid crystalline nicotinic acid derivatives (C1, C2, C3, and C4) were used as complementary H-bond donor/acceptor counterparts. The liquid crystalline properties of the nicotinic acid derivatives, the polymers and their complexes were investigated by DSC and POM. Methylene spacers present at the terminal position of the nicotinic acid derivatives played a key role in mesophase arrangements. The columnar phase exhibited by the nicotinic acid derivatives completely disappeared in the H-bonded complexes to afford a nematic phase, thereby substantiating the complex formation.
- Saravanan,Ambili,Kannan
-
experimental part
p. 217 - 222
(2011/10/18)
-
- 4′-(2-(2-Ethoxyethoxy)ethoxy)biphenyl-4-carboxylic acid-a polar smectogen for amphipathic liquid crystals
-
We describe a new calamitic smectogen and some of its esters with a three-block molecular architecture (polar oxyethylene chain, rigid biphenyl and non-polar aliphatic chain) which were characterised by a combination of optical, thermical, X-ray and computational techniques. The title compound is a valuable smectogenic building block for amphipathic functional organic materials.
- Montani, Rosana S.,Hegguilustoy, Claudia M.,Del Rosso, Pablo G.,Donnio, Bertrand,Guillon, Daniel,Garay, Raúl O.
-
scheme or table
p. 5231 - 5234
(2009/12/06)
-
- Reentrant SmCPA phases: Unusual polymorphism variant SmA-SmCSPA-Colob-SmCSPA observed in new bent-core mesogens
-
A new homologous series of achiral five-ring bent-core mesogens is presented. The mesophase behaviour has been studied by polarizing microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical measurements. The homologues with shorter terminal chains (C8, C 12) form an SmCPA phase, homologues with longer chains (C14, C16, C18) show liquid-crystalline tetramorphism with a sequence SmA-SmCSPA-Col ob-SmCSPA. The SmCPA phases are structurally identical and differ only in the mechanism of polar switching. The switching of the high-temperature SmCSPA phase takes place through the collective rotation of the molecules around their long axes whereas in the reentrant SmCSPA phase the switching is based on the director rotation around the tilt cone. By the application of an electric field the Colob phase can be irreversibly transformed to an SmCP A phase. In a limited temperature range the SmA phase shows a reversible field-induced transition into the SmCSPF phase. The electro-optical response of the mesophases is discussed on the basis of the structural features of these phases. The Royal Society of Chemistry 2006.
- Shreenivasa Murthy,Bodyagin,Diele,Baumeister,Pelzl,Weissflog
-
p. 1634 - 1643
(2007/10/03)
-
- Fine-tuning of relative metal - Metal distances within highly ordered chiral 2D nanopatterns
-
The two-dimensional nano-patterning of a series of neutral alkoxy/alkyl-functionalised bis(salicylaldehydato)/bis(aldiminato)copper(II) and -palladium(II) complexes at a liquid/solid (highly oriented pyrolytic graphite, HOPG) interface has been studied by scanning tunnelling microscopy (STM). The relative metal - metal distances were tuned stepwise in two dimensions by ligand design. Exchange of the carbonyl O-atom for NH or N-alkyl units effects different intermolecular interactions such as weak hydrogen bonds and steric effects that deter mine, together with the van der Waals forces between the alkyl chains, the relative arrangements of the complexes. Further variation of the length and position of the alkoxy side chains as well as the exchange of CuII for PdII affords an absolute fine-tuning of the surface structures. Highly resolved STM images of the resultant highly ordered adlayers allow us to establish detailed models of the molecular 2D arrays and to classify them into three basic chiral pattern types. Homochirality within the individual domains is induced by the highly regular deposition of the prochiral complexes from the same enantiotopic face. In the case of the C12 O-substituted bis(salicylaldiminato) (NH) CuII complex Cu5, a secondary structure occurs as a racemic mixture of two chiral surface species deposited in a distinct alternating order.
- Zell, Philipp,Moegele, Florian,Ziener, Ulrich,Rieger, Bernhard
-
p. 3847 - 3857
(2008/02/07)
-
- Synthesis of a novel antiferroelectric liquid crystal: Influence of biphenyl ester linkages on magnitude of spontaneous polarization
-
A novel AFLC compound, (S)-4-dodecyloxyphenyl-4-(2-methyl)-butyloxybiphenyldicarboxylate (DPMBBD), has been synthesized and its liquid crystalline behaviour is studied by thermal microscopy (TM), Diffrential Scanning Calorimetry (DSC), spontaneous polarization (Ps) and response times (τ) measurements. The preliminary investigations on the ferroelectric properties of the present material imply the presence of an antiferroelectric phase (Sm-CA*) with a high magnitude of spontaneous polarization. Further, the molecular contributions towards the magnitude of spontaneous polarization in the antiferroelectric phase are discussed in the light of ester linkages of biphenyl moiety.
- Kumar, Poluri A.,Pisipati, Venkata G.K.M.
-
p. 161 - 170
(2007/10/03)
-
- Bent tridentate receptors in calamitic mesophases with predetermined photophysical properties: New luminescent lanthanide-containing materials
-
A new synthetic strategy has been developed to introduce bent and rigid tridentate 2,6-bis(benzimidazol-2'-yl)pyridine cores into rodlike ligands L(11-17). The crystal structure of the nonmesogenic ligand L13 (C39H37N5O4, triclinic, P1, Z = 2) shows the expected trans-trans conformation of the tridentate binding unit, which provides a linear arrangement of the semirigid aromatic sidearms. The crystal structure of the related mesogenic ligand L16 (C61H81N5O4, triclinic, P1, Z = 2) demonstrates the fully extended conformation adopted by the lipophilic side chains, leading to a slightly helically twisted I-shaped molecule. A rich and varied mesomorphism results which can be combined with the simultaneous tuning of electronic and photophysical properties via a judicious choice of the spacers between the rigid central core and the semirigid lipophilic sidearms. Ligands L13,14 react with Ln(NO3)3·χH2O to give quantitatively and selectively the neutral 1:1 complexes [Ln(L')(NO3)3] (Ln = La to Lu), which are stable in the solid state at room temperature but partially dissociate in acetonitrile to give the cationic species [Ln(L')(NO3)2]+. The crystal structure of [Lu-(L13)(NO3)3]·3CH3CN (30, LUC45H46N11O13, monoclinic, C2/c, Z = 8) reveals a U-shaped arrangement of the ligand strand arising from the cis-cis conformation of the coordinated tridentate binding unit. This drastic geometric change strongly affects the thermal behavior and the photophysical and electronic properties of the lipophilic complexes [Ln(L14)(NO3)3]. Particular attention has been focused on structure-properties relationships, which can be modulated by the size of the lanthanide metal ions.
- Nozary, Homayoun,Piguet, Claude,Tissot, Paul,Bernardinelli, Gérald,Bünzli, Jean-Claude G.,Deschenaux, Robert,Guillon, Daniel
-
p. 12274 - 12288
(2007/10/03)
-
- Tilt Angle Variation as a Function of Chain Length and Temperature in the Smectic C Phases of p,Alkoxyphenyl-p,Alkoxybenzoates
-
The variation of the tilt angle with temperature in the smectic C phase has generally been shown to be non-existent or very slow for compounds or mixtures with the nematic-smectic C transition, while in the case of systems with the smectic A-smectic C transition, a relation between the steepness of this variation, near the transition, and the width of the smectic A domain has been observed.In this work, the variation of tilt angle in the smectic C phase is described for p-alkoxyphenyl-p-alkoxybenzoate homologous series, for which the evolution of polymorphism can be controlled systematically, by varying stepwise the length of the aliphatic chains, and for which large domains can be obtained for each type of phase sequence, nematic-, smectic A- and isotropic-smectic C.After completing the discussion made previously on the incidence of chain length on polymorphism, we confirm that the variation of tilt angle with temperature is slowest for compounds with intermediate chain lengths corresponding to the largest smectic A temperature range; this variation becomes continuously steeper when the smectic A domain becomes narrow.In addition, we show that the same description can be extended to the other types of phase sequences, by using the hypothesis of a virtual smectic A-smectic C transition above the observed nematic- or isotropic-smectic C transition.In fact, short chain lengths for homologues with a nematic/smectic C transition, or long chain lengths for homologues with an isotropic/smectic C transition, lead to an increase of the tilt angle at the phase transition and to a decrease of the amplitude of its variation with temperature; in our description, this behaviour corresponds to an increase of the temperature range between the real and virtual transitions.As a consequence, the homologues with very short and very long chain lengths show a quasi temperature-independent tilt angle, while the other homologues present a tilt angle variation similar to that observed for compounds exhibiting a smectic C/smectic A transition.This feature indicates that there is no need to distinguish between different types of smectic C phase.
- Heinrich, B.,Guillon, D.
-
-
- Synthesis of 4-alkoxyaryl β-D-glucopyranosides and their inhibitory effects on histamine release from rat peritoneal mast cells induced by concanavalin A
-
The inhibitory effects of newly synthesized 4-alkoxyaryl β-D- glucopyranosides on histamine release from rat peritoneal mast cells induced by concanavalin A were examined. A plot of hydrophobicity (k') against inhibitory activity of the compounds showed a distinct maximum, and 4- decyloxy-2,3,6-trimethylphenyl β-D-glucopyranoside was the most potent inhibitor among the tested compounds.
- Wang,Furukawa,Nihro,Kakegawa,Matsumoto,Satoh
-
p. 570 - 575
(2007/10/02)
-
- Synthesis and anti lipid-peroxidation activity of hydroquinone monoalkyl ethers
-
A series of hydroquinone monoalkyl ethers was synthesized and evaluated for anti lipid-peroxidation activity in rat liver microsomes. 4-Hexyloxy- 2,3,6-trimethylphenol (9), having a low redox potential, as well as ascorbic acid exhibited the strongest anti lipid-peroxidation activity (IC50 = 4.2 x 10-7 M). Structure-activity relationship studies demonstrated that the inhibitory effect of hydroquinone monoalkyl ethers on lipid peroxidation was increased by the acquisition of an optimum hydrophobicity and decreased by an insufficient or excessive hydrophobicity.
- Nihro,Furukawa,Sogawa,Wang,Miyataka,Matsumoto,Miki,Satoh
-
p. 576 - 579
(2007/10/02)
-
- Selective etherification of polyhydroxybenzenes using PEG 200 as solvent or cosolvent
-
The monoalkylation of hydroquinone is performed using PEG 200 as a solvent or a cosolvent.The effect on the selectivity of the base strength, the temperature, and the percentage of cosolvent are discussed.The substituted phenols were found to behave differently upon etherification.When a carboxylic function is present in the ring, the hydroxybenzoic acids were selectively etherified using pure PEG and sodium hydroxyde as a base.Substituted diphenols were selectively etherified using a mixture of PEG and dioxan and potassium hydrogencarbonate as a base.Keywords - etherification / selectivity / polyhydroxybenzenes / polyethylene glycol
- Berdague, P.,Perez, F.,Courtieu, J.,Bayle, J. P.
-
p. 475 - 480
(2007/10/02)
-
- LIQUID CRYSTALLINE PROPERTIES OF 4-N-ALKOXYPHENYL 4-NITROBENZOATES.
-
Twelve 4-alkoxyphenyl esters of 4-nitrobenzoic acid were synthesized. The mesophases were identified and the transition temperatures and enthalpies determined. The above series shows considerable similarity to the reverse analogues, i. e. , the 4-nitro-phenyl 4-n-alkoxybenzoates.
- Galewski,Sobczyk
-
-