67399-80-8Relevant academic research and scientific papers
Constitutional Isomers of Pentahydroxy-Functionalized Pillar[5]arenes: Synthesis, Characterization, and Crystal Structures
Al-Azemi, Talal F.,Vinodh, Mickey,Alipour, Fatemeh H.,Mohamod, Abdirahman A.
, p. 10945 - 10952 (2017/10/27)
We herein report the preparation of constitutional isomers of pentahydroxy-functionalized pillar[5]arenes via the deprotection of their benzylated derivatives by catalytic hydrogenation. The structures of the obtained isomers were then established using single crystal X-ray diffraction. We also found that the yield distribution of the different constitutional isomers was dependent on the nature of the substitution, as revealed by HPLC analysis of the crude mixture. Finally, further characterization of the separated constitutional isomers indicated that they possess different melting points, NMR spectra, crystal structures, and stacking patterns in the solid state.
Intramolecular charge transfer interactions and molecular order of rod like mesogens
Reddy, M. Guruprasad,Lobo, Nitin P.,Varathan,Easwaramoorthi,Narasimhaswamy
, p. 105066 - 105078 (2015/12/30)
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.
Synthesis and liquid crystal property of new fluoro coumarin carboxylates
Mahadevan, Kittappa M.,Harishkumar, Hosanagara N.,Masagalli, Jagadeesh N.,Srinivasa, Hosapalya T.
, p. 20 - 35 (2013/08/24)
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.
Arene ruthenium dichloro complexes containing isonicotinic ester ligands: Synthesis, molecular structure and cytotoxicity
Khan, Farooq-Ahmad,Therrien, Bruno,Süss-Fink, Georg,Zava, Olivier,Dyson, Paul J.
, p. 49 - 56 (2013/06/27)
A series of p-cymene ruthenium dichloro complexes containing isonicotinic ester ligands, [(arene)RuCl2NC5H4-4-COO-C 6H4-p-O-(CH2)n-CH3] (n = 1: 1, n = 3: 2, n = 5: 3, n = 7: 4, n = 9: 5, n = 11: 6, n = 13: 7, n = 15: 8), were prepared from p-cymene ruthenium dichloro dimer and the corresponding isonicotinic ester ligand. The single-crystal X-ray analysis of 1 shows the molecule to adopt the usual pseudo-tetrahedral piano-stool geometry, the isonicotinic ester ligand being coordinated through the nitrogen atom. The cytotoxicity of all complexes and of the free ligands was studied towards human ovarian cancer cells; high activities were observed only for n = 9 (presenting a chain with ten carbon atoms), both as far as the free ligands and the complexes are concerned. Based on this result, a new isonicotinic ester ligand with a C10 substituent containing a terminal alcohol function, NC 5H4-4-COO-C6H4-p-O-(CH 2)10-OH, was synthesized by a four-step method, and arene ruthenium complexes thereof, [(arene)RuCl2NC5H 4-4-COO-C6H4-p-O-(CH2) 10-OH] (arene = C6H6: 9a, arene = p-MeC 6H4Pri: 9b, arene = C6Me 6: 9c) were prepared. The complexes 9a and 9b show indeed remarkable anticancer activities, the IC50 values for human ovarian cancer cells being in the submicromolar range. The highest cytotoxicity was observed for complex 9b, with IC50 values of 0.18 μM for A2780 and 3.04 μM for the cisplatin-resistant mutant A2780cisR.
Reentrant SmCPA phases: Unusual polymorphism variant SmA-SmCSPA-Colob-SmCSPA observed in new bent-core mesogens
Shreenivasa Murthy,Bodyagin,Diele,Baumeister,Pelzl,Weissflog
, p. 1634 - 1643 (2007/10/03)
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.
Separation and identification of stereoisomers of a tetrameric side- chain liquid crystalline cyclic siloxane
Mann,Haley,Lacey
, p. 353 - 360 (2007/10/03)
For the first time the four stereoisomers of a tetrameric side-chain liquid crystalline cyclic siloxane have been isolated in a pure state by high performance liquid chromatography. The structure of one of the stereoisomers was confirmed by 1H, 13C and 29Si NMR. The structures of the remaining three stereoisomers were assigned by using evidence from the literature and their liquid crystalline thermal properties. All four stereoisomers and the isomeric mixture exhibited calamitic SmC and SmA phases; no discotic phases were found.
Ferrocene und Ferrocenophane mit dipolaren Strukturelementen
Pagel, Karsten,Werner, Andreas,Friedrichsen, Willy
, p. 109 - 124 (2007/10/02)
The synthesis of ferrocenyl substituted pyrazoles (3, 7, 14 and 15) and the subsequent reaction of these compounds with reactive malonic acid derivatives yielding dipolaric pyrazolopyrazol-4-ium-3-olates (4, 8, 16 and 17) is described.Key words: Ir
A Liquid Crystalline Ferrocenophane
Werner, Andreas,Friedrichsen, Willy
, p. 365 - 366 (2007/10/02)
The first example of a liquid crystal with a ferrocenophane unit is described.
Ameliorations et simplification de la synthese des ethers phenoliques par alkylation d'ions phenates: catalyse par transfert de phase solide-liquide sans solvant
Loupy, Andre,Sansoulet, Jean,Zand, Farchid Vaziri-
, p. 1027 - 1035 (2007/10/02)
Several aryl ethers can be obtained in excellent yields under mild and economical conditions in the absence of organic solvents by reacting stoechiometric amounts of corresponding phenol, finely ground KOH and alkyl bromides in the presence of 2percent Aliquat 336.This method is very favourable compared with recent works dealing with anionic activation.
