30752-20-6Relevant academic research and scientific papers
Azo bond formation on metal surfaces
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
supporting information, p. 1458 - 1464 (2020/12/14)
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.
Alkyloxy modified pyrene fluorophores with tunable photophysical and crystalline properties
Kapf, Andreas,Eslahi, Hassan,Blanke, Meik,Saccone, Marco,Giese, Michael,Albrecht, Marcel
supporting information, p. 6361 - 6371 (2019/04/25)
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.
New pyridine based liquid crystalline esters with different terminal chains
Karanl?k, Gürkan,Ocak, Hale,Bilgin Eran, Belk?z
, (2019/08/22)
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.
Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self-Assembly
W?hrle, Tobias,Gündemir, Rafet,Frey, Wolfgang,Knecht, Friederike,K?hn, Andreas,Laschat, Sabine
supporting information, p. 4149 - 4159 (2017/03/31)
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.
Synthesis and Characterization of a New Series of Paramagnetic Ferroelectric Liquid Crystalline Nitroxide Radicals
Uchida, Yoshiaki,Tamura, Rui,Suzuki, Katsuaki,Takahashi, Hiroki,Aoki, Yoshio,Nohira, Hiroyuki
, p. 89 - 106 (2015/09/01)
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.
Ferroelectric response in an achiral non-symmetric bent liquid crystal:C12C10
Subrahmanyam,Chalapathi,Mahabaleshwara,Srinivasulu,George,Potukuchi
, p. 173 - 184 (2014/08/18)
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
Electron acceptors based on functionalizable cyclopenta[hi]aceanthrylenes and dicyclopenta[de,mn]tetracenes
Wood, Jordan D.,Jellison, Jessica L.,Wang, Lichang,Plunkett, Kyle N.,Finke, Aaron D.
supporting information, p. 15783 - 15789,7 (2020/08/24)
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-
Solution processable symmetric 4-alkylethynylbenzene end-capped anthracene derivatives
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
experimental part, p. 541 - 548 (2012/05/05)
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.
NOVEL ORGANIC SEMICONDUCTOR COMPOUND, AND ORGANIC THIN FILM TRANSISTOR USING THE SAME
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Page/Page column 35-36, (2008/12/04)
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.
Buchwald protocol applied to the synthesis of N-heterotolan liquid crystals
Vasconcelos, Ursula B.,Schrader, Abel,Vilela, Guilherme D.,Borges, Antonio C.A.,Merlo, Aloir A.
, p. 4619 - 4626 (2008/09/20)
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
