- Azo bond formation on metal surfaces
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The formation of azo compounds via redox cross-coupling of nitroarenes and arylamines, challenging in solution phase chemistry, is achieved by on-surface chemistry. Reaction products are analyzed with a cryogenic scanning tunneling microscope (STM) and X-ray photoelectron spectroscopy (XPS). By using well-designed precursors containing both an amino and a nitro functionality, azo polymers are prepared on surface via highly efficient nitro-amino cross-coupling. Experiments conducted on other substrates and surface orientations reveal that the metal surface has a significant effect on the reaction efficiency. The reaction was further found to proceed from partially oxidized/reduced precursors in dimerization reactions, shedding light on the mechanism that was studied by DFT calculations.
- Meng, Xiangzhi,Klaasen, Henning,Viergutz, Lena,Schulze Lammers, Bertram,Witteler, Melanie C.,M?nig, Harry,Amirjalayer, Saeed,Liu, Lacheng,Neugebauer, Johannes,Gao, Hong-Ying,Studer, Armido,Fuchs, Harald
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supporting information
p. 1458 - 1464
(2020/12/14)
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- Alkyloxy modified pyrene fluorophores with tunable photophysical and crystalline properties
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Novel alkyloxy modified 2,7-di-tert-butyl-4,5,9,10-tetra(arylethynyl)pyrenes were prepared through a straightforward Sonogashira coupling approach. Optical properties such as quantum yields and absorption/emission spectra of the fluorophores were investigated by UV/Vis and fluorescence measurements. Aggregation induced excimer formation of the chromophores in polar solvents and in the solid state was proved by the presence of a characteristic bathochromically shifted emission band and a decrease of the emission capability. These results strongly indicate the unexpected observation that the excimer formation of adjacent pyrene rings is not prevented by the introduction of bulky tert-butyl substituents. Single-crystal X-ray and computational analyses reveal the co-planar alignment of adjacent molecules and the presence of π-π-stacking in the molecular packing of the pyrene polyaromatics. Furthermore, fluorescence, DSC and POM measurements indicate that the aggregation behaviour, the thermal characteristics and the crystalline properties are significantly influenced by changing structural features of the attached functional groups at the periphery of the pyrene core.
- Kapf, Andreas,Eslahi, Hassan,Blanke, Meik,Saccone, Marco,Giese, Michael,Albrecht, Marcel
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supporting information
p. 6361 - 6371
(2019/04/25)
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- New pyridine based liquid crystalline esters with different terminal chains
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The synthesis, structural and mesomorphic characterization of new pyridine-based methyl esters carrying a n-alkoxy chain or 3,7-Dimethyloctyloxy branched group at terminal have been presented. The liquid crystalline properties of the new pyridine-based calamitic molecules have been investigated by polarized optical microscopy and differential scanning calorimetry. New compounds exhibit enantiotropic smectic A mesophase at a variable mesomorphic range depending on alkoxy chain length and branching at terminal. The presence of a branched terminal group in chiral or racemic form gives rise to a sharply increase in mesomorphic range as well as decrease in crystallization points by preserving mesophase type.
- Karanl?k, Gürkan,Ocak, Hale,Bilgin Eran, Belk?z
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- Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self-Assembly
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A series of MIDA (N-methylimino diacetic acid) boronates carrying 4-alkoxy, 3,4-bisalkoxy, or 3,4,5-trisalkoxyphenyl substituents were synthesized and their mesomorphic properties characterized by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) techniques such as small- and wide-angle X-ray scattering (SAXS and WAXS, respectively). Most derivatives were liquid crystalline. In the case of mono- and bisalkoxy-substituted derivatives, C6 chains already induced smectic A (SmA) mesophases despite the bulky MIDA head group. With increasing chain length, columnar hexagonal (Colh) phases replaced SmA phases in the disubstituted series. Quantum chemical calculations on a series of MIDA boronates show that the B?N bond is a dative bond with a positive charge on the boron atom and negative charges on the nitrogen and oxygen atoms. In addition, no π-interaction between the aryl moiety and B?N bond was found, thus the mesogenic unit is electronically decoupled from the MIDA head group. These theoretical findings were supported by IR and Raman spectra as well as by asingle crystal structure analysis of 4-ethoxyphenyl MIDA boronate. Calculations of the electrostatic potential of the MIDA boronate reveal a special polarity pattern that can support the formation of a two-dimensional network and is likely to explain the liquid crystalline self-assembly. The absence of any electronic cross-talk between the MIDA head group and B-aryl or B-alkyl substituents allows the efficient tailoring of the mesophase type through variation of the substituents.
- W?hrle, Tobias,Gündemir, Rafet,Frey, Wolfgang,Knecht, Friederike,K?hn, Andreas,Laschat, Sabine
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supporting information
p. 4149 - 4159
(2017/03/31)
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- Synthesis and Characterization of a New Series of Paramagnetic Ferroelectric Liquid Crystalline Nitroxide Radicals
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A new series of all-organic liquid-crystalline (LC) chiral radical compounds,trans-1-alkoxyphenyl-4-[(4-(4-alkoxyphenyl)-2,5-dimethylpyrrolidine-1-oxy-2-yl)-benzylideneamino]benzenes (1) with various alkyl chains, containing a chiral nitroxide unit in the mesogen core were synthesized and their LC properties were fully characterized. The enantiomerically enriched compounds (2S,5S)-1 showed N, TGBA, SmA and SmC phases, while the racemates (±)-1 exhibited N, SmA and SmC phases. The phase transition behavior and the ferroelectric properties of the SmC phase of (2S,5S)-1 differed from those of previously reported analogues with an ester group as a substitute for the imino group of (2S,5S)-1. Some of the (2S,5S)-1 series showed a temperature-dependent spontaneous polarization PS (θ) inversion. We discuss the origin of this difference in terms of their molecular structures optimized by molecular orbital calculations. The phase transition behavior supports the hypothesis that the large φ, which is defined as the angle between the molecular long axis (one of the principal axes of inertia) and the direction of the dipole moment in each molecule, results in the stabilization of the SmA (SmA) phase.
- Uchida, Yoshiaki,Tamura, Rui,Suzuki, Katsuaki,Takahashi, Hiroki,Aoki, Yoshio,Nohira, Hiroyuki
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- Ferroelectric response in an achiral non-symmetric bent liquid crystal:C12C10
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An achiral Non-Symmetric Bent Liquid Crystal (BLC) with a Oxadiazole based hetero cyclic central moiety, abbreviated as C12C10 viz., dodecyl[4-{5-(4′-decyloxy)biphenyl-4-yl}-1,2,4-oxadiazol-3-yl]benzoate, exhibiting FerroElectric (FE
- Subrahmanyam,Chalapathi,Mahabaleshwara,Srinivasulu,George,Potukuchi
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p. 173 - 184
(2014/08/18)
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- Solution processable symmetric 4-alkylethynylbenzene end-capped anthracene derivatives
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New candidates composed of anthracene and 4-alkylethynylbenzene end-capped oligomers for OTFTs were synthesized under Sonogashira coupling reaction conditions. All oligomers were characterized by FT-IR, mass, UV-visible, and PL emission spectrum analyses, cyclic voltammetry (CV), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), 1H-NMR, and 13C-NMR. Investigation of their physical properties showed that the oligomers had high oxidation potential and thermal stability. Thin films of DHPEAnt and DDPEAnt were characterized by spin coating them onto Si/SiO 2 to fabricate top-contact OTFTs. The devices prepared using DHPEAnt and DDPEAnt showed hole field-effect mobilities of 4.0 × 10-3 cm2/Vs and 2.0 × 10-3 cm2/Vs, respectively, for solution-processed OTFTs.
- Jang, Sang Hun,Kim, Hyunjin,Hwang, Min Ji,Jeong, Eun Bin,Yun, Hui Jun,Lee, Dong Hoon,Kim, Yun-Hi,Park, Chan Eon,Yoon, Yong-Jin,Kwon, Soon-Ki,Lee, Sang-Gyeong
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experimental part
p. 541 - 548
(2012/05/05)
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- Electron acceptors based on functionalizable cyclopenta[hi]aceanthrylenes and dicyclopenta[de,mn]tetracenes
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We report the synthesis and selective functionalization of two externally fused cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) and demonstrate their electron accepting behavior. 2,7-Bis(trimethylsilyl) cyclopenta[hi]aceanthrylene (1) and 2,8-
- Wood, Jordan D.,Jellison, Jessica L.,Wang, Lichang,Plunkett, Kyle N.,Finke, Aaron D.
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supporting information
p. 15783 - 15789,7
(2020/08/24)
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- NOVEL ORGANIC SEMICONDUCTOR COMPOUND, AND ORGANIC THIN FILM TRANSISTOR USING THE SAME
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The present invention relates to novel mono- molecular organic semiconductor compounds and organic thin film transistors comprising the same. The organic semiconductor compounds according to the present invention are characterized by a structure of an acene derivative substituted with acetylene groups at both ends, a structure of anthracene derivative substituted with acetylene groups, or a structure of a multi-nuclear aromatic derivative functionalized by naphthalene having an electron-donor substituent at both ends.
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Page/Page column 35-36
(2008/12/04)
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- Buchwald protocol applied to the synthesis of N-heterotolan liquid crystals
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A homologous series of the new N-heterotolans 8a-d were synthesized using two cross-coupling reactions mediated by copper and palladium/copper. The final compounds present the phenyl-pyridyl framework connected by the acetylene group. The evaluation of th
- Vasconcelos, Ursula B.,Schrader, Abel,Vilela, Guilherme D.,Borges, Antonio C.A.,Merlo, Aloir A.
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p. 4619 - 4626
(2008/09/20)
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- Synthesis, characterization, and fluorescence quenching of novel cationic phenyl-substituted poly(p-phenylenevinylene)s
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Three new phenyl-substituted poly(p-phenylenevinylene) (Ph-PPV) derivatives with amino-functionalized groups were synthesized through either Gilch reaction for poly{2,5-bis[4′-2-(N,N-diethylamino)ethoxyphenyl]-1,4-phenylenevinylene (P1) or Wittig reaction for poly{2,5-bis(4′-decyloxyphenyl)-1,4-phenylenevinylene-alt-2,5-bis[4′ -2-(N,N-diethylamino)ethoxyphenyl]-1,4-phenylenevinylene} (P2) and poly(2,5-bis{4′-2-[2-(2-methoxyethoxy)ethoxy]ethoxyphenyl}-1,4-phenylenevi nylene-alt-2,5-bis[4′-2-(N,N-diethylamino)ethoxyphenyl]-1,4- phenylenevinylene) (P3). Green light-emitting cationic polymers, poly{2,5-bis(4′-decyloxyphenyl)-1,4-phenylenevinylene-alt-2,5-bis[4′ -2-(N,N,N-triethylammonium)ethoxyphenyl]-1,4-phenylenevinylene} dibromide (P2′) and poly(2,5-bis{4′-2-[2-(2-methoxyethoxy)ethoxy]ethoxyphenyl}-1,4-phenylenevi nylene-alt-2,5-bis[4′-2-(N,N,N-triethylammonium)ethoxyphenyl]-1, 4-phenylenevinylene) dibromide (P3′), were prepared from the neutral polymers P2 and P3, respectively. Water solubility was achieved on P3′ through increase of the hydrophilicity of the side chains. The acid-assistant reversible solubility of P1 makes it promising in preparing light-emitting multilayer devices. On the basis of FT-IR and 1H NMR spectra, it was found that P1 is primarily of trans-vinyl while P2 and P3 are of 80% and 81% cis-vinyl, respectively, which depends on the polymerization method employed. The bulky phenyl substituents successfully impeded the interchain interaction which led to quantum efficiency as films comparable to that of solutions. Quaternization also resulted in more twisted conformation of the polymer main chain which was supported by both blue-shifted absorption and reduced quantum efficiency of P2′ and P3′ in solutions and as films than that of the neutral polymers. The fluorescence of P3′ was efficiently quenched by an anionic quencher Fe(CN)64-, Ksv of which is 3.3 × 106 M-1. However, a modified Stern-Volmer plot showed that 9% of the fluophores could not be accessible to the quencher, which may result from the twisted conformation or intermolecular aggregation.
- Fan, Qu-Li,Lu, Su,Lai, Yee-Hing,Hou, Xiao-Yuan,Huang, Wei
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p. 6976 - 6984
(2007/10/03)
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- Novel sulfonyldiazomethanes, photoacid generations, resist compositions, and patterning process
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A chemical amplification type resist composition contains as a photoacid generator a sulfonyldiazomethane compound of formula (1) wherein R is H or C1-4 alkyl or alkoxy, G is SO2 or CO, R3 is C1-10 alkyl or Csu
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- Synthesis and mesomorphic properties of some liquid crystals with 2,3,5,6-tetrafluorophenylene unit
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Nine fluorosubstituted liquid crystals have been synthesized and their mesomorphic properties have been studied by texture observation in a polarizing microscope and confirmed by DSC. They show enantiotropic smectic A and nematic phases. The effect of ter
- Tang,Yang, Yong Gang,Wen
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- Liquid crystal compounds, mixtures and devices
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An electroclinic device having two spaced cell walls each bearing electrode structures and treated on at least one facing surface with an alignment layer, a layer of a smectic liquid crystal material enclosed between the cell walls, where the liquid crystal material contains one or more of the compounds described by formula I as defined in the specification.
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Page column 30
(2008/06/13)
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- Synthesis and physical properties of thioester liquid crystals that exhibit an anti-ferro-anti phase sequencing
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The thioester unit has been commonly used to enhance the mesophase thermal stability and phase range in numerous liquid crystal materials. In this paper we report the synthesis of a homologous series of thioesters with similar structures to AS620 {(S)-(+)
- Nassif, Larissa,Jakli, Antal,Seed, Alexander J.
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p. 171 - 179
(2007/10/03)
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- Discotic liquid crystals of transition metal complexes, 31: Establishment of mesomorphism and thermochromism of bis[1,2-bis(4-n-alkoxyphenyl)ethane-1,2-dithiolene]nickel complexes
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Two series of bis[1,2-bis(4-n-alkylphenyl)ethane-1,2-dithiolene]nickel, Cn-Ni (n= 1-12), and bis[1,2-bis(4-n-alkoxyphenyl)ethane-1,2-dithiolene]nickel, CnO-Ni(n = 1-12, 14, 16, 18), have been synthesized. Their mesomorphism, thermochromism, supramolecular structures and π-acceptor property have been investigated by using different scanning calorimetry, polarizing microscopy, temperature-dependent X-ray diffraction technique, electronic spectroscopy and cyclic voltammetry. From the X-ray diffraction and electronic spectral results, it was established that the CnO-Ni complexes for n ≤ 10 exhibit two differently colored discotic lamellar (DL) mesophases whereas none of the Cn-Ni complexes has a mesophase, and that the thermochromism (brown→green) is attributable to a slow transformation from the Ni-Ni bonded dimers to the Ni-S bonded dimers.
- Horie,Takagi,Hasebe,Ozawa,Ohta
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p. 1063 - 1071
(2007/10/03)
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- Liquid crystal compounds, mixtures and devices
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An electoclinic device having two spaced cell walls each bearing electrode structures and treated on at least one facing surface with an alignment layer, a layer of a smectic liquid crystal material enclosed between the cell walls, where the liquid crystal material contains one or more of the compounds described by formula I as defined in the specification.
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- Chiral cyclohexyl compounds
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The present invention describes liquid crystal compounds which are suitable for use in liquid crystal devices including those which exploit the electroclinic effect.
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- Synthesis and liquid-crystalline properties of novel laterally connected twins: The influence of the connecting topology and the length of the rigid core
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Laterally ligated p-terphenyl twins containing 2-oxapropylene spacers have been synthesized. Their liquid-crystalline properties were investigated by polarizing microscopy, calorimetry and X-ray scattering. The mesophase stability depends strongly on the topology of connection. It was found that the connection of the mesogenic units at the peripheries of the rigid cores gave twins with the highest clearing temperatures and the broadest smectic C (SC) ranges. Shifting the connecting units to the middle of the rigid cores diminished their mesophase stability. The X-ray investigations indicated that the thickness of the smectic layer was nearly independent of the position of the lateral connecting group when the same mesogens were linked. Also, twins incorporating a 1,4-disubstituted phenyl ring and a biphenyl rigid core have been prepared and they were found to exhibit broad mesomorphic ranges. Another kind of twins was obtained by the lateral-terminal connection of a p-terphenyl rigid core and a 2,5-diphenyl-1,3,4-thiadiazole calamitic unit. Again, a remarkable influence of the connecting position was observed.
- Andersch, Jens,Tschierske, Carsten,Diele, Siegmar,Lose, Dirk
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p. 1297 - 1307
(2007/10/03)
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- P-terphenyl derivatives and liquid crystalline compositions
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New p-terphenyl derivatives useful as components for preparing practical ferroelectric liquid crystalline compositions and excellent in chemical stability, as well as liquid crystalline compositions containing at least one of the p-terphenyl derivatives.
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