- The Structure of 4-Methoxy-ONN-azoxybenzene and Oxygen Transfer Reaction of 4-Methoxyazoxybenzenes in Sulfuric Acid
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The structure of 4-methoxy-ONN-azoxybenzene(1α) has been determined by X-ray analysis.In sulfuric acid 1α gave a rearrangement product 4-hydroxy-4'-methoxyazobenzene, together with 4-methoxyazobenzene and 4-methoxy-NNO-azoxybenzene.
- Yamamoto, Jiro,Yamashita, Hiroshi,Miyagawa, Hisato,Abe, Toshio,Tsukihara, Tomitake
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- Low excitation energy band of 4-hydroxyazobenzene derivatives
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The low excitation energy band appeared in the electronic spectra of some 4-hydroxyazobenzene derivatives is assigned to an electronic transition of the type η-?*.It is concluded that 4-hydroxyazobenzene derivatives exist mainly in the true azo form.On the other hand, the visible spectra of the azo compound; 4-hydroxy-2-carboxyazobenzene is interpreted on the basis that this compound exists in a tautomeric equilibrium of the type azo hydrazone, originating from the carboxyl group at the ortho position to the azo one.
- Mahmoud, M. R.,Ibrahim, S. A.,Hamed, M. A.
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- Polarity dependent photoisomerization of ether substituted azodyes: Synthesis and photoswitching behavior
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Two new ether substituted azodyes were synthesized and characterized by different spectral analysis such as 1H NMR, 13C NMR, FTIR and UV/Vis. Synthesized compounds were used to study the photoisomerization phenomenon by using UV-Vis
- Gan, Siew Mei,Pearl, Zynia Fernandes,Yuvaraj,Lutfor,Gurumurthy, Hegde
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- Combined main-chain/side-chain liquid crystalline polymer with main-chain on the basis of "jacketing" effect and side-chain containing azobenzene groups
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Combining the concept of "flexible spacer" which can bring liquid crystalline (LC) properties to the side-chains and the side-group "jacketing" effect which can result in main-chain with rod-like conformation, we have synthesized a new combined main-chain
- Xie, He-Lou,Wang, Shao-Jie,Zhong, Guan-Qun,Liu, Yi-Xin,Zhang, Hai-Liang,Chen, Er-Qiang
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- ELECTROPHILIC CATALYSIS BY CYCLODEXTRINS
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The catalysis of an aromatic electrophilic substitution reaction by cyclodextrins is reported.The catalysis can be explained on the basis of the electron rich character of the interior of the cyclodextrin cavity.Kinetic analysis of this reaction in the presence of cyclodextrins indicate binding and catalysis.
- Ye, Hongping,Rong, Ding,D'Souza, Valerian T. D.
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- Synthesis and mesomorphic behaviour of achiral four-ring unsymmetrical bent-core liquid crystals: Nematic phases
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Achiral four ring unsymmetrical bent-core liquid crystals derived from 3-amino-2-methylbenzoic acid have been designed and synthesized with an imine, ester and photochromic azo linking moieties. These hockey-stick shape resembling bent molecules possess a
- Paul, Manoj Kumar,Kalita, Gayatri,Laskar, Atiqur Rahman,Debnath, Somen,Gude, Venkatesh,Sarkar, Dipika Debnath,Mohiuddin, Golam,Varshney, Sanjay Kumar,Nandiraju Rao
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- Effect of methoxy group instead of polar group in the nematic phase of four-ring bent-core liquid crystals
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Two achiral four-ring bent-core liquid crystal possessing an alkoxy chain at one end of the molecules and methoxy group at the other end are investigated by using the optical polarizing microscope, electro-optical studies, and dielectric spectroscopy. Bot
- Nafees, Amina,Kalita, Gayatri,Paul, Manoj Kumar,Sinha, Aloka,Rao, Nandiraju V. S.
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- Photoswitchable NIR-Emitting Gold Nanoparticles
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Photo-switching of the NIR emission of gold nanoparticles (GNP) upon photo-isomerization of azobenzene ligands, bound to the surface, is demonstrated. Photophysical results confirm the occurrence of an excitation energy transfer process from the ligands to the GNP that produces sensitized NIR emission. Because of this process, the excitation efficiency of the gold core, upon excitation of the ligands, is much higher for the trans form than for the cis one, and t→c photo-isomerization causes a relevant decrease of the GNP NIR emission. As a consequence, photo-isomerization can be monitored by ratiometric detection of the NIR emission upon dual excitation. The photo-isomerization process was followed in real-time through the simultaneous detection of absorbance and luminescence changes using a dedicated setup. Surprisingly, the photo-isomerization rate of the ligands, bound to the GNP surface, was the same as measured for the chromophores in solution. This outcome demonstrated that excitation energy transfer to gold assists photo-isomerization, rather than competing with it. These results pave the road to the development of new, NIR-emitting, stimuli-responsive nanomaterials for theranostics.
- Bonacchi, Sara,Cantelli, Andrea,Battistelli, Giulia,Guidetti, Gloria,Calvaresi, Matteo,Manzi, Jeannette,Gabrielli, Luca,Ramadori, Federico,Gambarin, Alessandro,Mancin, Fabrizio,Montalti, Marco
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- Side Chain Liquid Crystalline Polyoxetanes with a Spacer-Separated Azobenzene Moiety. I. Preparation and Characterization
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Several oxetane derivatives carrying the azobenzene moiety at the C-3 position of the oxetane ring through the spacer arms of differing lengths were prepared by a substitution reaction of the corresponding bromide or p-toluenesulfonate residue of the oxetane with 4-hydroxyazobenzenes.The polymers of these oxetane derivatives were readily obtained by cationic ring-opening polymerization using the adequately increased amount of a THF*BF3 complex as an initiator at 20-30 deg C.The liquid crystalline property of the polymers thus obtained were examined by differential scanning calorimetry and by optical polarized microscopy.From these measurements the influences of the p'-substituted azobenzene and of the spacer arm on the liquid crystalline property were found.
- Motoi, Masatoshi,Noguchi, Kunimasa,Arano, Akio,Kanoh, Shigeyoshi,Ueyama, Akihiko
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- Thermal and photo alignment behavior of polymers in multiply-layered films composed of polyethylene imines having azobenzene side chain groups and polyvinyl alcohol
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Polyethylene imines having 4-methoxyazobenezene group through methylene spacer groups (PEI6M) were synthesized and their photochemical, thermooptical as well as photoorientational behavior were investigated. PEI6M films showed high dichroism and order par
- Kamruzzaman, Mohammad,Ogata, Tomonari,Kuwahara, Yutaka,Ujiie, Seiji,Kurihara, Seiji
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- LIQUID CRYSTALS - 8. NEMATOGENIC COMPOUNDS WITH A TERMINAL DIMETHYLAMINOETHOXY GROUP.
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Six p,p prime -disubstituted azo- and azoxybenzenes in which one of the terminal groups is 2-N,N-dimethylaminoethoxy, and their hydrochlorides were synthesized. The three azoxybenzene derivatives exhibit nematic mesomorphism. Neither the azobenzenes nor a
- Alpay,Schroeder,Schroeder
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- Non-symmetric liquid crystal dimer containing a carbohydrate-based moiety
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The synthesis and characterisation of a novel non-symmetric liquid crystal dimer, 1-[3-O-(d-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-4′-oxy)] octane is reported. This exhibits glassy behaviour and a highly interdigitated smectic A phase in which the aromatic and alkyl structural fragments overlap. Variable temperature infrared spectroscopy reveals that the strength and extent of hydrogen bonding within the system does not show a marked change at either the glass transition or at the smectic A-isotropic transition. This observation indicates that the smectic A-isotropic transition is driven by changes in the van der Waals interactions between the molecules while hydrogen bonded aggregates persist into the isotropic phase.
- Cook, Andrew G.,Wardell, James L.,Brooks, Nicholas J.,Seddon, John M.,Martinez-Felipe, Alfonso,Imrie, Corrie T.
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- Low-temperature nematic phase in azo functionalised reactive hockey stick mesogens possessing lateral methyl group
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We report, the design, synthesis and mesomorphic behaviour of new hockey stick mesogens containing photochromic azo group and a reactive double bond. The structure of the compounds resemble the hockey stick due to unequal distribution of the phenyl rings
- Paul, Manoj Kumar,Saha, Sandip Kumar,Kalita, Gayatri,Bhattacharya, Barnali,Sarkar, Utpal
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- Photoisomerization and Mesophase Formation in Azo-Ionic Liquids
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Ionic liquids present a versatile, highly tunable class of soft functional materials. Aside from being low melting salts, they can be endowed with additional functionalities. In N-alkylimidazolium halides, which are a prominent class of ionic liquids (ILs), the imidazolium cation was linked via an ether-bridge to an azobenzene unit in order to obtain photoresponsive materials through photoinduced trans-cis isomerization. The azobenzene unit, in turn, was modified with electron-donating or -withdrawing groups such as methyl-, tert-butyl-, methoxy-, N,N-dimethylamino, and nitro groups to study their influence on the photoisomerization and phase behavior. Endowing the imidazolium additionally with a long alkyl chain allows the materials to potentially form liquid crystalline (LC) mesophases before melting into the isotropic liquid. All studied compounds qualify as ionic liquids, and all, except for the nitro-compound, show the formation of smectic mesophases melting to the isotropic liquid. The compounds with the bulkiest aliphatic substituent, the tert-butyl, shows the lowest melting point, the largest mesophase window, and an efficient photochemical trans-cis conversion (>90%). In summary, by tuning sterically and electronically the cationic part of ILs, a photoswitchable room temperature liquid crystal could be developed and design guidelines for photoresponsive ionic liquids could be obtained.
- Renier, Olivier,Bousrez, Guillaume,Stappert, Kathrin,Wilk-Kozubek, Magdalena,Adranno, Brando,Pei, Hanwen,Spielberg, Eike T.,Smetana, Volodymyr,Mudring, Anja-Verena
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p. 214 - 225
(2019/12/24)
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- The role of conductivity and molecular mobility on the photoanisotropic response of a new azo-polymer containing sulfonic groups
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We report the preparation of a new light-responsive side-chain terpolymer containing azobenzenes, as chromophoric components, sulfonic groups, as polar components, and methacrylate groups, as film forming components, and we provide a detailed characterisa
- Alauddin, Sakinah Mohd,Aripin, Nurul Fadhilah Kamalul,Velayutham,Chaganava, Irakli,Martinez-Felipe, Alfonso
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- A Novel Side-Chain Liquid Crystal Elastomer Exhibiting Anomalous Reversible Shape Change
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Liquid crystalline elastomers (LCEs) have been actively investigated as stimuli-controlled actuators and soft robots. The basis of these applications is the ability of LCEs to undergo a reversible shape change upon a liquid crystalline (LC)-isotropic phas
- Ge, Feijie,Han, Li,Soldera, Armand,Tong, Xia,Yin, Lu,Zhang, Wei,Zhao, Yue
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supporting information
p. 15129 - 15134
(2020/07/04)
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- Novel Phenyldiazenyl Fibrate Analogues as PPAR α/γ/δ Pan-Agonists for the Amelioration of Metabolic Syndrome
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The development of PPARα/γ dual or PPARα/γ/δ pan-agonists could represent an efficacious approach for a simultaneous pharmacological intervention on carbohydrate and lipid metabolism. Two series of new phenyldiazenyl fibrate derivatives of GL479, a previously reported PPARα/γ dual agonist, were synthesized and tested. Compound 12a was identified as a PPAR pan-agonist with moderate and balanced activity on the three PPAR isoforms (α, γ, δ). Moreover, docking experiments showed that 12a adopts a different binding mode in PPARγ compared to PPARα or PPARδ, providing a structural basis for further structure-guided design of PPAR pan-agonists. The beneficial effects of 12a were evaluated both in vitro, on the expression of PPAR target key metabolic genes, and ex vivo in two rat tissue inflammatory models. The obtained results allow considering this compound as an interesting lead for the development of a new class of PPAR pan-agonists endowed with an activation profile exploitable for therapy of metabolic syndrome.
- Giampietro, Letizia,Laghezza, Antonio,Cerchia, Carmen,Florio, Rosalba,Recinella, Lucia,Capone, Fabio,Ammazzalorso, Alessandra,Bruno, Isabella,De Filippis, Barbara,Fantacuzzi, Marialuigia,Ferrante, Claudio,MacCallini, Cristina,Tortorella, Paolo,Verginelli, Fabio,Brunetti, Luigi,Cama, Alessandro,Amoroso, Rosa,Loiodice, Fulvio,Lavecchia, Antonio
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supporting information
p. 545 - 551
(2019/03/19)
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- Structure modification of an active azo-compound as a route to new antimicrobial compounds
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Some novel (phenyl-diazenyl)phenols 3a-g were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against bacteria and fungi, was used as lead for modifications and optimization of the structure, by introduction/removal or displacement of hydroxyl groups on the azobenzene rings. The aim of this work was to evaluate the consequent changes of the antimicrobial activity and to validate the hypothesis that, for these compounds, a plausible mechanism could involve an interaction with protein receptors, rather than an interaction with membrane. All newly synthesized compounds were analyzed by 1H-NMR, DSC thermal analysis and UV-Vis spectroscopy. The in vitro minimal inhibitory concentrations (MIC) of each compound was determined against Gram-positive and Gram-negative bacteria and Candida albicans. Compounds 3b and 3g showed the highest activity against S. aureus and C. albicans, with remarkable MIC values of 10 μg/mL and 3 μg/mL, respectively. Structure-activity relationship studies were capable to rationalize the effect of different substitutions on the phenyl ring of the azobenzene on antimicrobial activity.
- Concilio, Simona,Sessa, Lucia,Petrone, Anna Maria,Porta, Amalia,Diana, Rosita,Iannelli, Pio,Piotto, Stefano
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- Thermostable birefringent copolyimide films based on azobenzene-containing pyrimidine diamines
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Azobenzene (azo)-containing polymers have attracted continuous attention due to their excellent photosensitivity. However, practical applications of their photo-induced birefringence have been hampered by low thermal stability. In this work, we report a s
- Tong, Faqin,Chen, Zhao,Lu, Xuemin,Lu, Qinghua
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p. 10375 - 10382
(2017/10/19)
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- Synthesis of diamine monomer with azo and polyimide prepared from diamine monomer
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The invention discloses synthesis of a diamine monomer with azo and polyimide prepared from the diamine monomer. The structural formula of the polyimide is shown in the specification. The polyimide is synthesized through polycondensation of the diamine mo
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Paragraph 0008-0012; 0018
(2017/01/05)
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- Method for preparing polyimide polymer with azo-pyrimidine structure unit
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The invention relates to a method for preparing a diamine monomer with an azo-pyrimidine structure and a method for preparing a polyimide polymer by adopting the diamine monomer with the azo-pyrimidine structure. The preparation method comprises the following steps: carrying out a coupling reaction on 4-substituted aniline and sodium phenate to obtain 4-hydroxy-4'-substituted azobenzene; and carrying out nucleophilic substitution on the 4-hydroxy-4'-substituted azobenzene and dibromoalkane to generate bromo-azobenzene, and reacting the bromo-azobenzene with 4,6-diamido-2-mercaptopyrimidine to obtain the diamine monomer; and carrying out condensation polymerization on the diamine monomer with dianhydride to obtain polyimide. The pyrimidine structure is introduced into the diamine monomer, so that the charge transfer complex effect of aromatic rings of polyimide is reduced, and the glass transition temperature of the polyimide is reduced; and the azo group has photo-induced anisotropy, and an azo unit is introduced into the polyimide by alkyl chains having different lengths, so that the heterogeneous degree of the azo group can be effectively regulated, and the application of the polyimide in alignment films and other optical fields can be improved to a great extent.
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Paragraph 0068
(2016/10/09)
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- Mesomorphism of azo-esters and chalcone-esters
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AOne chalcone-ester homologous series of mesogens α-4-[4/-n-alkoxybenzoyloxy phenyl β-4//methoxy benzoyl ethylenes (A) and one azo-ester homologous series of mesogens p-(p/-n-alkoxybenzoyloxy) phenyl azo-p//-methoxy benzene (B) being structurally similar are discussed. Both series (A) and (B) differ in respect of central bridges linking two phenyl rings. Mesomorphic properties start from 6th and 1st member of series (A) and (B) respectively. In series (A), 6th to 12th members show both smectogenic and nematogenic properties, and the 14th and 16th members show only nematogenic property. While in series (B), 1st to 10th members show nematogenic properties, 11th member shows both smectogenic and nematogenic properties, while 12th member shows only smectogenic property. Thermal stability of series (A) is relatively high as compared to series (B). Transition temperatures are observed through hot stage polarizing microscope by the miscibility method. Analytical data support the structure of molecules. Textures of series (A) in nematic are threaded and Schlieren in SmecticSmectic A type, while that of series (B) in nematic are threaded in SmecticSmectic A and smectic C.
- Jain,Sharma, Vinay S.,Chauhan,Patel
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p. 102 - 111
(2016/07/14)
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- Conformation of Novel Azo-Dyes Bearing End-Capped Oligo(ethylene glycol) Studied by UV-vis and NMR Spectroscopy
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Two novel azo-dyes bearing an end-capped oligo(ethylene glycol) chain were synthesized and then studied by UV-visible and NMR spectroscopy. For both azobenzenes, the end-capped oligo(ethylene glycol) segment is on the para position of the first phenyl ring. On the second phenyl ring, a methoxy group is added on the para position for one azo-dye and no substitution group on the other, which made them electronically a push-push and a push system, respectively. The presence of the methoxy group changes significantly the absorption and the photoisomerization behaviors and results in a much less intense absorbance for the trans isomer and a shift from 350 to 360 nm. In the kinetic studies the azobenzene bearing a methoxy group shows a zero-order and a first-order kinetics as a function of the time scale of the study as well as an aggregation phenomenon. This azo-dye in different solvents has been studied by 1H NMR and pulsed gradient NMR experiments to understand the effects of the photoisomerization and the aggregation on the self-diffusion of these molecules in solutions.
- Kouvatas, Cassandre,Baille, Wilms E.,Ortíz-Palacios, Jesús,Aguilar-Ortíz, Edgar,Rivera, Ernesto,Zhu
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p. 12318 - 12324
(2015/09/28)
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- Nitric Oxide Catalysis of Diazene E / Z Isomerization
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Nitric oxide is an efficient catalyst for the cis-trans (E/Z) isomerization of diazenes. We compare the effect of room temperature solutions bearing low concentrations of nitric oxide, nitrogen dioxide, or oxygen on the rate of cis-trans isomerization, CTI, of the alkene bond in stilbene and on the azo double bond in azobenzene, as well as in four azo derivatives as measured by UV-vis spectroscopy. These rate enhancements can be as large as 3 orders of magnitude for azobenzene in solution. A mechanism is proposed where catalysis is promoted by the interaction of the nitric oxide with the diazene nitrogen lone pairs. Density functional theory, B3LYP/6-311++g suggests that the binding of NO to the diazene should be weak and reversible but that its NO adduct has an E/Z isomerization barrier of 7.5 kcal/mol.
- Bohle, D. Scott,Rosadiuk, Kristopher A.
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p. 7145 - 7151
(2015/08/11)
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- Photoliquefiable ionic crystals: A phase crossover approach for photon energy storage materials with functional multiplicity
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Ionic crystals (ICs) of the azobenzene derivatives show photoinduced IC-ionic liquid (IL) phase transition (photoliquefaction) upon UV-irradiation, and the resulting cis-azobenzene ILs are reversibly photocrystallized by illumination with visible light. The photoliquefaction of ICs is accompanied by a significant increase in ionic conductivity at ambient temperature. The photoliquefaction also brings the azobenzene ICs further significance as photon energy storage materials. The cis-IL shows thermally induced crystallization to the trans-IC phase. This transition is accompanied by exothermic peaks with a total ΔH of 97.1 kJmol-1, which is almost double the conformational energy stored in cisazobenzene chromophores. Thus, the integration of photoresponsive ILs and self-assembly pushes the limit of solar thermal batteries.
- Ishiba, Keita,Morikawa, Masa-Aki,Chikara, Chie,Yamada, Teppei,Iwase, Katsunori,Kawakita, Mika,Kimizuka, Nobuo
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supporting information
p. 1532 - 1536
(2015/02/05)
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- New fluorescent symmetrically substituted perylene-3,4,9,10-dianhydride- azohybrid dyes: Synthesis and spectroscopic studies
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Five phenolic azo-dyes (3a-e) were synthesized by diazo coupling of the suitably substituted anilines (1a-e) with phenol at low temperature in alkaline medium. The resulting dyes have low solubility in aqueous medium due to lack of carboxylic or sulfonic
- Saeed, Aamer,Shabir, Ghulam
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- Anisotropic fluorescence emission of ionic complex induced by the orientation of azobenzene unit
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A series of azobenzene-containing fluorescent complexes with stilbene fluorescent unit were prepared based on the ionic self-assembly approach. The incorporation of the stilbene unit did not change the lamellar structure of the azobenzene-containing compl
- Wu, Jun,Lu, Xuemin,Yi, Zeyuan,Shan, Feng,Lu, Qinghua
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p. 3376 - 3383
(2013/07/28)
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- Facile one-pot/one-step technique for preparation of side-chain functionalized polymers: Combination of SET-RAFT polymerization of azide vinyl monomer and click chemistry
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An azido-containing functional monomer, 11-azido-undecanoyl methacrylate, was successfully polymerized via ambient temperature single electron transfer initiation and propagation through the reversible addition-fragmentation chain transfer (SET-RAFT) meth
- Shen, Qiong,Zhang, Jian,Zhang, Shuangshuang,Hao, Yigang,Zhang, Wei,Zhang, Weidong,Chen, Gaojian,Zhang, Zhengbiao,Zhu, Xiulin
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experimental part
p. 1120 - 1126
(2012/06/18)
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- Synthesis and characterization of photoactive azobenzene-based chromophores containing a bulky cholesteryl moiety
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This study describes the synthesis of a series of azobenzene-based chromophores bearing pendent bulky cholesteryl groups, using esterification reactions. The chromophores were composed of liquid crystalline mesophases with six or eleven methylene segments as spacers, and with electron-donating (OCH3) and electron-withdrawing (NO2) terminal groups. The target compounds were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimetry, polarizing optical microscopy, absorption, and photoluminescence spectroscopies. All the azobenzene derivatives with six or eleven methylene segments revealed chiral nematic phases. We investigated the effects of these photochromic compounds' structures on E/Z photoisomerization under UV irradiation. Chromophores containing the electron-withdrawing nitro-group (NO2) underwent a faster rate of Z to E isomerization in darkness than the electron-donating (OCH3) groups did; the isomerization process proceeded via a rotation mechanism. Self-assembled aggregates of C6 solution exhibited enhanced fluorescence in THF/water mixtures at 10% water fraction.
- Yang, Po-Chih,Lu, Ya-Ling,Li, Chung-Yuan
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scheme or table
p. 129 - 137
(2012/06/04)
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- Synthesis, thermal stability and photoresponsive behaviors of azobenzene-tethered polyhedral oligomeric silsesquioxanes
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A series of azobenzene-tethered polyhedral oligomeric silsesquioxane (POSS) derivatives, i.e. monoazobenzene-substituted POSS (MonoAzo-POSS), bisazobenzene-substituted POSS (BisAzo-POSS) and triazobenzene-substituted POSS (TriAzo-POSS), were synthesized through the amidation acidylation of aminopropylisobutyl POSS and benzoic acid derivatives (AzoMs) with one, two and three azobenzene groups (AzoM1, AzoM2 and AzoM3). Their structures were characterized by FT-IR, 1H NMR, 13C NMR and mass spectra, and their thermal stability and photoresponsive behaviors in DMF solutions were evaluated with TGA, XRD and UV-vis spectra, respectively. The results indicated that the thermal stability and photoisomerization of azobenzenes could be effectively controlled by their molecular structure. In MonoAzo-POSS, the large steric hindrance of POSS destroys the molecular ordering and limits the molecular packing, contributing to its poor thermal stability. And the low molecular ordering of MonoAzo-POSS offers an azo group with large free space, and its trans-cis photoisomerization rate increases accordingly. But, in BisAzo-POSS and TriAzo-POSS, the incorporation of POSS units does not impact on the regularity of azobenzenes obviously, and the hindrance effect of nanosize POSS on the molecular motion plays a primary role in increasing their high thermal stability. Their photoisomerization rates decrease due to the steric hindrance of POSS and the unfolding structure of the azo moieties in BisAzo-POSS and TriAzo-POSS.
- Zhou, Jinlan,Zhao, Yongchen,Yu, Kaichao,Zhou, Xingping,Xie, Xiaolin
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scheme or table
p. 2781 - 2792
(2012/01/14)
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- Fluorescent nanoparticles assembled from a poly(ionic liquid) for selective sensing of copper ions
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Fluorescent nanoparticles were formed from a poly(ionic liquid) through ion interactions. The fluorescent nanoparticles show highly fluorescent intensity and stability to UV light irradiation and were utilized for highly sensitive and selectivity fluoresc
- Cui, Kun,Lu, Xuemin,Cui, Wei,Wu, Jun,Chen, Xumeng,Lu, Qinghua
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supporting information; experimental part
p. 920 - 922
(2011/02/25)
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- Synthesis of azobenzene-functionalized star polymers via RAFT and their photoresponsive properties
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Azobenzene-functionalized star polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. First, azobenzene-functionalized linear macro chain transfer agents (Macro-CTA) were synthesized by RAFT polymerization of 6-[4-(4′-Methoxyphenylazo)phenoxy] hexylmethacrylate (MAz6Mc) using 2-(2′-cyanopropyl)dithiobenzoate (CPDB) as RAFT agent in presence of AIBN as initiator in anisole. Subsequently, star azopolymers were synthesized by polymerization of a difunctional azomonomer, BMA2Az, with resultant Macro-CTA in presence of AIBN as initiator in anisole. Star azopolymers were characterized by GPC and spectroscopic methods. Thermal properties of star azopolymers were determined by DSC and TMA. Molecular weight versus conversion and molecular weight versus polymerization time attest to living polymerization characteristics. Photoisomerization behaviors of star azopolymers were studied by irradiation of both UV and visible light. Surface relief gratings were inscribed on star azopolymer films upon exposure to an interference pattern of (RCP + RCP) Ar+ laser. A diffraction efficiency of 20% was obtained by exposure of Star-8 K(2.6 K) polymer film to an (RCP + RCP) Ar+ laser for about 30 min. Surface relief grating structures were investigated by AFM and polarized optical microscopy.
- Alam, Md. Zahangir,Shibahara, Akihisa,Ogata, Tomonari,Kurihara, Seiji
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experimental part
p. 3696 - 3703
(2012/02/05)
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- Cellulose-based liquid crystalline photoresponsive films with tunable surface wettability
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We report on a new type of liquid crystalline cellulosic films with light controllable reversible wettability. The films are prepared from a thermotropic cellulose derivative functionalized with azo-containing groups. These groups exhibit dynamic changes
- Pinto,Kundu,Brogueira,Cruz,Fernandes,Aluculesei,Godinho
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scheme or table
p. 6330 - 6337
(2012/06/01)
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- Influence of the photo-active azo cross-linker spacer on the opto-mechanics of polysiloxane elastomer actuators
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Nematic liquid single crystal elastomers (LSCEs) that contain azobenzenes as cross-linkers have a clear application in the field of light-controlled actuators. They are able to modify their macroscopic dimensions upon irradiation with UV light and furthermore relax back thermally or by irradiation with visible light. Many efforts have been put forward to improve the photo-mechanical effect. However, there are no previous studies about the role of the length of the photo-active cross-linker spacer on the opto-mechanics of light-controlled actuators. In this way, we have prepared several photo-active side-chain nematic polysiloxane LSCEs that contain 4,4′- dialkoxyazobenzenes as cross-linkers, which bear spacers of different lengths. The opto-mechanical behaviour of the different LSCEs prepared has been analyzed. The use of photo-active cross-linkers with long spacers yields actuators with higher mechanical responses under irradiation with UV light. Neither the irradiation nor the thermal relaxation time of the actuator depends on the spacer length.
- Garcia-Amoros, Jaume,Finkelmann, Heino,Velasco, Dolores
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body text
p. 1094 - 1101
(2011/09/14)
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- Stable holographic gratings with small-molecular trisazobenzene derivatives
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We present a series of small-molecular trisazobenzene chromophores, including, for instance, 1,3,5-tris{[4-[4-[(4-cyanophenyl)azo]phenoxy]butyryl] amino}benzene that feature a remarkably stable light-induced orientation in initially amorphous thin-film ar
- Kreger, Klaus,Wolfer, Pascal,Audorff, Hubert,Kador, Lothar,Stingelin-Stutzmann, Natalie,Smith, Paul,Schmidt, Hans-Werner
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supporting information; experimental part
p. 509 - 516
(2010/03/25)
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- Fluorine-substituted azobenzene destabilizes polar form of optically switchable fulgimide unit in copolymer system
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Fulgimide and various size and electronic nature of substituents on the terminal position of azobenzene in the pendant homo/copolymethacrylates were synthesized. Differential scanning calorimetry analysis indicates the homopolymer possessing C-form fulgimide unit exhibited higher Tm than that of E-form of the homopolymer and revealed C-form is highly ordered. Thermal stability suggests azobenzene homopolymers with electron donating substituents have high thermal stability than electron withdrawing substituents. Polarized optical microscopy observation disclosed homopolymers viz., NI, CY, FL, ME, and T-ME exhibited liquid crystalline mesophases between their Tm and Ti. Optical properties of homo/copolymers were investigated by UV-vis and fluorescence spectroscopy. UV-vis spectroscopy displayed C-form fulgimide absorption in F-co-FL around 482 nm which is around 40 nm lesser than C-form of substituted azobenzene copolymers. Similarly, fluorescence pattern of F-co-FL by UV irradiation exhibited emission intensity slowly increased to certain level then decreases with two new emissions at 430 and 480 nm attributed to terminal position of fluorine atom on azobenzene destabilizes polar form (C-form) fulgimide unit in the copolymer.
- Chinnusamy, Saravanan,Palaninathan, Kannan
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scheme or table
p. 1565 - 1578
(2011/02/26)
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- Zn2+ cation triggers self-assembly of cyclen into a stable metallogel
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A novel type of ligands contained 1,4,7,10-tetrazacyclododecane and functionalized by two azobenzene moieties grafted with two alkyl chains was designed and synthesized. The ligands with long alkyl chains can form metallogels in the presence of Zn2+ cations. The formation of metallogel was followed by NMR and electronic spectral detection. The morphology of the xerogels is varied with the equivalent of Zn2+ cations and the concentration of the gel. Spectral and structural analysis indicated that the driving forces of the gel formation were attributed to intermolecular hydrophobic interactions between alkyl chains and π-π interaction between azobenzenes.
- Shu, Tianmin,Wu, Junchen,Zou, Ying,Liu, Keyin,Chen, Liqing,Yi, Tao
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scheme or table
p. 184 - 192
(2011/11/29)
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- An investigation of the reduction in aqueous acetonitrile of 4-methoxybenzenediazonium ion by the tetrakis(acetonitrile)Cu(i) cation catalysed by hydrogenphosphate dianion
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In aqueous acetonitrile containing a phosphate buffer, 4- methoxybenzenediazonium ion is reduced by one or more of the partially aquated cations derived from tetrakis(acetonitrile)Cu(i) cation in this medium. Investigation of the reaction mechanism indicates the rate determining step to be the association of the diazonium ion with the hydrogenphosphate dianion to give an adduct which then undergoes reduction by Cu(i). The reaction gives a range of products which have been identified and quantified by GC. One of these, 4-methoxyphenol was unexpected in the reducing conditions; its presence could be explained by the disproportionation of a 4-methoxyphenylcopper(ii) complex giving bis(4-methoxyphenyl)copper(iii) which reacts with water to produce the phenol and an equivalent amount of methoxybenzene. A scheme is proposed which accounts for all the observed products and computer modelling gives a satisfactory description of the distributions of the five major products as functions of the relative proportions of the reactants for dilute conditions and those where the reductant is in excess. When the diazonium ion is in excess, the behaviour of the model and the experimental reactant accountability suggest the occurrence of additional reactions which give products unobserved by GC. This journal is The Royal Society of Chemistry.
- Hanson, Peter,Taylor, Alec B.,Walton, Paul H.,Timms, Allan W.
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p. 679 - 698
(2008/03/27)
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- Ultra microanalysis of ferric ion using triazene and capillary electrophoresis
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The triazene compound {2,2′-[3-(4-methoxyphenyl)triaz-2-ene-1,1-diyl] diethanol} was utilized for the high sensitive and quantitative detection of ferric ion. Copyright
- Nishiwaki, Keiji,Taga, Atsushi,Yamaya, Masako,Morita, Yusuke,Suzuki, Yukiko,Honda, Susumu,Matsuo, Keizo
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p. 1418 - 1419
(2007/10/03)
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- Liquid crystalline properties of polyguanidines
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Modified polyguanidines were prepared, and their liquid crystalline properties were studied using optical polarizing microscopy and X-ray diffraction. Parameters examined include chirality, the uniformity of the lengths of side chains, and attached side-chain mesogens. If the side chains on the repeat units are identical, then polymer has a more ordered structure in both solution and the solid state. Uniform lengths of the side chains are also important. Poly(N,N′-di-n-hexylguanidine), poly-I, exhibited a lyotropic smectic texture in contrast to a nematic texture of poly(N-(rac)-2-phenylethyl)- N′-methylguanidine) (poly-(rac-II)). Optically pure poly(N-((R)-2- phenylethyl)-2-methylguanidine) (poly-(R-II)) formed a cholesteric texture, whereas the corresponding racemic polyguanidine, poly-(rac-II), formed a nematic texture. Additionally, poly-(R-II) displayed a mesophase at a lower critical concentration than either poly-I or poly-(rac-II), implying that poly-(R-II) is suffer than these two other derivatives. Polyu(N-6-((4′-methoxyphenylazo) phenyl-4-oxy)hexyl-N′-n-hexylguanidine) (poly-IV), one of combined liquid crystalline structures (liquid crystalline backbone plus liquid crystalline side chains), displayed a lyotropic nematic texture presumably due to the strong dipolar-dipolar interaction between the main chain and side chains that folds the appendages parallel to the molecular axis. Poly(N-12-((4′- methoxybiphenyl-4-oxy)dodecyl-N′-n-dodecylguanidine) (poly-V) and poly(N,N′-di-n-dodecylguanidine) (poly-VI) exhibited thermotropic liquid crystalline behavior.
- Kim, Jeonghan,Novak, Bruce M.,Waddon, Alan John
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p. 8286 - 8292
(2007/10/03)
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- Monodispersive unsymmetrical tetramers exhibiting a columnar phase
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Oligomeric liquid crystals that are formed by joining two or more mesogenic segments axially through a flexible spacer (or multiple spacers) seem to be interesting materials from the points of view of both basic research and practical applications owing to their multifunctional characteristics and properties similar to those of polymers while retaining fluidity, viscosity etc. associated with those of low molar mass liquid crystals. The synthesis and evaluation of mesomorphic behavior of two novel monodispersive unsymmetrical tetramesogens have been presented here in detail. The molecular design, of these tetramesogens incorporates the cholesteryl ester (as a chiral entity), biphenyl (as a supportive entity for mesomorphism), azobenzene (as a photoactive mesogen), and tolan (as a half-disc) segments interconnected through even-even-odd and odd-even-odd alkylene spacers. The target liquid crystalline tetramers have been realized by employing convenient synthetic strategies, which involves the preparation of two important unsymmetrical dimers and finally their condensation. The molecular structures of all the intermediates and unsymmetrical tetramers have been characterized by spectroscopic analyses. The mesomorphic property of both the unsymmetrical tetramers has been evaluated by optical microscopic, calorimetric and X-ray diffraction studies. Our study reveals that both oligomers show an identical mesophase. While X-ray studies suggest that the structure of the mesophase is similar to that of a rectangular columnar (Colr) mesophase; a pseudoisotropic texture was seen under the microscope.
- Yelamaggad,Anitha Nagamani,Hiremath, Uma S.,Shankar Rao,Krishna Prasad
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p. 207/[507]-229/[529]
(2007/10/03)
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- Mesogenic biphenyl derivatives with azo and ester central linkage
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Biphenyl nucleus comprises one of the most interesting research areas in the study of relations between chemical constitution and mesomorphic properties. Few biphenyl derivatives with azo and ester central linkage having following general formula have been synthesized and their mesomorphic properties were evaluated. Where R=-H, -OCH3, R'=-CH3, -OCH3, -OC2H5, -OC4H9; X=-H, -Br. All the synthesized compounds were characterized by elemental analysis and spectroscopic methods.
- Prajapati
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p. 769 - 777
(2007/10/03)
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- Preparation and characterazation of chromophor group containing cyclotriphosphazenes: II azo chromophor carrying some cyclotriphosphazenes
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Some new substituted cyclotriphosphazenes were prepared by the reaction of hexachlorocyclotriphosphazene and 4-hydroxyazo compounds such as 4-hydroxyazobenzene, 4′-ethyl-4-hydroxyazobenzene, 4′-tertbutyl-4-hydroxyazobenzene, 4′-methoxy-4-hydroxyazobenzene, 3′,4′-dichloro-4-hydroxyazobenzene, 2′-chloro-4-hydroxyazobenzene and 2′-methoxy-5′-chloro -4-hydroxyazobenzene. The structure of the compounds with the general formula [NP(OC6H4N=N-Ar)2]3. was determined by UV-VIS, IR, 1H-NMR and elemental analysis.
- Odabasoglu, Mustafa,Turgut, Guenseli,Kocaokutgen, Hasan
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- Liquid crystalline properties of azobenzenes: I. 4-methoxy-, 4-ethoxy-, 4-propoxy-and 4-butoxy-4′-alkyloxyazobenzenes
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Liquid crystalline properties of four series of azobenzenes, 4-methoxy-4-alkyloxyazobenzenes (azo-1-n), 4-ethoxy-4′-alkyloxyazobenzenes (azo-2-n), 4-propoxy-4′al-kyloxyazobenzenes (azo-3-n) and 4-butoxy-4′-alkyloxyazobenzenes (azo-4-n), were investigated. By polarizing microscopy nematic and smectic C mesophases were detected. By DSC and TOA thermo-optics the parameters of phase transitions were measured. A typical odd-even effect of the clearing temperature was found. No smectic phase was detected in the first three series, even for the longest alkyloxy chains. The smectic C appears for the first time in the butoxy family, starting from the undecyloxyl derivative. In each series a polymorphism in the solid state was detected, especially significant in the propoxy and butoxy family, that was explained in terms of the ODIC phases.
- Galewski,Hofmanska,Zielinska
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p. 1357 - 1371
(2007/10/03)
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- Photoresponsive dendrimers
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Benzyl aryl ether dendrimers with azobenzene central linkers undergo reversible cisltrans isomerization of the azobenzene moiety upon exposure to ultraviolet light.
- Junge, Denise M.,McGrath, Dominic V.
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p. 857 - 858
(2007/10/03)
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- Conducting polymeric side-chain liquid crystals and an orientation layer using the same
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Conducting polymeric side chain liquid crystals are prepared by incoporating liquid crystalline compounds in a main chain selected from the group consisting of acetylene derivatives and thiophene derivatives. The liquid crystal has conductivity and liquid
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- Mesogenic 4-(2,3-Epoxypropoxy)-4'-alkoxyazoxybenzenes
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Optimal conditions for preparation of 4-(2,3-epoxypropoxy)-4'-alkoxyazoxybenzenes were developed, and 10 mesogenic homologs (n = 1-10) possessing an extended nematic mesophase were synthesized.Nonyloxy and decyloxy derivatives of epoxyazoxybenzene exhibit also smectic mesomorphism.
- Burmistrov, V. A.,Kuz'mina, S. A.,Koifman, O. I.
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p. 351 - 353
(2007/10/03)
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- Mesogenic properties of liquid crystals having a chiral semiflexible joint
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Two homologous series of mesogenic enantiomers with chiral semiflexible joint, -C*H(CH3)CH2COO-, are examined. High twist power and presence of blue phases with short lattice period are found for eleven examined compounds. Some effects of chirality in reentrant system are discussed. On phase diagram of enantiomers the SmAd phase area is shifted toward longer homologues as compared to racemates. In result, an island of the SmAd phase in the cholesteric sea exists on binary phase diagrams of R- and S- enantiomers. Triple divergence of the pitch in the cholesteric phase of a pure compound is observed.
- Gorecha,Pyzuk,Mieczkowski
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- Effect of Structure of Photoresponsive Molecules on Photochemical Phase Transition of Liquid Crystals I. Synthesis and Thermotropic Properties of Photochromic Azobenzene Derivatives
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Seventeen azobenzene derivatives were synthesized and their thermotropic properties were examined.They are classified into three groups.In the first group, 4-cyanobiphenyl moieties are attached to both sides of azobenzene through various alkyl spacers: AB(nCB)2 where n = 3, 4, 5 and 6.In the second group, the 4-cyanobiphenyl moiety is attached to one side of the azobenzene, while the substituent of the other side was kept as OCH3:1ABnCB, where n = 3, 4, 5, 6 and 8.The third group is the azobenzene derivatives which possess alkoxy substituents at both para positions of azobenzene (nABm) or at various positions of the azobenzene phenyl rings (k,1ABn,m).The introduction of the 4-cyanobiphenyl group at the end(s) of the molecules is based on the attempt of highly efficient photochromic molecules to induce photochemical phase transition of liquid crystals by providing the photochromic trigger molecules with high affinity to the host liquid crystal.Both 1ABnCB and AB(nCB)2 exhibited the liquid crystalline phases, whereas among nABm and k,1ABn,m, only 1AB8 and 8AB8 showed the liquid crystalline phase.The 1ABnCB series exhibited a distinct odd-even variation in phase transition temperatures as well as enthalpy and entropy changes with the length of the flexible spacers, while the AB(nCB)2 series did not show clear odd-even variation except for the liquid crystal to isotropic phase transition temperatures.
- Ikeda, T.,Miyamoto, T.,Kurihara, S.,Tsukada, M.,Tazuke, S.
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p. 357 - 371
(2007/10/02)
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- The Synthesis of Specifically and Selectively Deuteriated 4,4'-Bisalkoxyazoxybenzene Derivatives
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In connection with deuterium n.m.r. studies of molecular motion in liquid crystals we have developed a number of methods for the synthesis of selectively deuteriated 4,4'-bisalkoxyazoxybenzenes.This paper is concerned with (i) the labelling of specific methylene segments of the alkoxy-chains, (ii) the labelling of the aromatic nucleus, and (iii) the selective enrichment of the deuterium content of one alkoxy-chain relative to the other.Our studies of the n.m.r. spectra of these liquid crystals have shown that there is not (as has sometimes been supposed) a monotonic decrease in C-D quadrupole splitting in passing from the oxygen to the CD3 end of the alkoxy-chain.In -PAA (p-azoxyanisole) we have also shown that the smaller splitting is associated with the CD3O group nearest to the NO end of azoxy-group.Whereas the photorearrangement of azoxy-compounds is normally regiospecific, the photorearrangement of PAA selectively deuteriated in one methoxy-group is unusual in that it leads to isotopically scrambled products.
- Boden, Neville,Bushby, Richard J.,Clark, Leslie D.
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p. 543 - 551
(2007/10/02)
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- BASIC PROPERTIES OF 4-ARYLAZO-PHENOLS AND 4-ARYLAZO-ANISOLES
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The conditions in which 4-arylazo-phenols and 4-arylazo-anisoles have basic properties have been studied.We have also determined the equilibrium constants of the reactions between 4-arylazo-phenols or 4-arylazo-anisoles with perchloric acid in nitromethane, acetonitrile and acetic acid.Conclusions have been drawn from the influence of the nature of solvent and substituent at the benzene ring on equilibrium constant values.
- Nesterowicz, Marianna,Korewa, Ryszard
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p. 1085 - 1092
(2007/10/02)
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