35108-00-0Relevant academic research and scientific papers
Fullerene soot and a fullerene nanodispersion as recyclable heterogeneous off-the-shelf photocatalysts
Jozeliūnait?, Augustina,Val?eckas, Domantas,Orentas, Edvinas
, p. 4104 - 4111 (2021/02/02)
Metal-free heterogeneous photocatalysis, which requires no prior catalyst immobilization or chemical modification and can operate in green solvents, represents a highly-sought after, yet currently still underdeveloped, synthetic method. In this report we present a comparative study which aims to evaluate the use of unmodified fullerene soot and a fullerene nanodispersion as non-soluble and quasi-soluble carbon-based photocatalysts, respectively, for sulfide oxidation and other transformations using oxygen as an oxidant in ethanol. A wide range of sulfoxides were successfully prepared with good yields and chemoselectivity using a very low catalyst loading. The fullerene soot photocatalyst is easily recovered and shows excellent stability of the catalytic properties. The reaction was shown to proceed via a singlet oxygen pathway and has a high selectivity for aliphatic sulfides, whereas the oxidation of thioanisoles can be accomplished using an amine mediated electron transfer mechanism. The applicability of the fullerene nanodispersion as a general purpose photocatalyst was demonstrated in radical cyclization, boronic acid oxidation and imine formation reactions.
Chemoselective and site-selective peptide and native protein modification enabled by aldehyde auto-oxidation
Purushottam, Landa,Adusumalli, Srinivasa Rao,Chilamari, Maheshwerreddy,Rai, Vishal
supporting information, p. 959 - 962 (2017/01/17)
We report a chemoselective and site-selective formylation of ?-amine in native proteins. The aldehyde auto-oxidation re-routing, regulated generation of formate, and reversible N-terminus protection drive the transformation. It labels a single ?-amine in a pool of its copies, other nucleophilic residues, and α-amine. The extension of the methodology leads to site-selective acylation.
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.
Novel macro metallomesogens derived from simple dihydroxy benzenes
Senthilkumar, Natarajan,Raghavan, Aravamudhan,Narasimhaswamy, Tanneru,Kim, Il-Jin
, p. 129 - 139 (2013/06/04)
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.
Synthesis and mesomorphic properties of novel [1,2,3]-triazole mesogenic based compounds
Benbayer, Chahinez,Kheddam, Narimane,Sa?di-Besbes, Salima,Givenchy, Elisabeth Taffin De,Guittard, Frédéric,Grelet, Eric,Safer, Abdel Mounaim,Derdour, A?cha
, p. 22 - 28 (2013/03/13)
A series of five-membered heterocyclic 1,2,3-triazole derivatives with different substituents in N1 position was synthesized. The heterocyclic moiety was connected through an ester function to a p-decyloxyphenyl or p-decyloxybiphenyl tails Polarized micro
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.
Structure-function relationships in liquid-crystalline halogen-bonded complexes
Bruce, Duncan W.,Metrangolo, Pierangelo,Meyer, Franck,Pilati, Tullio,Praesang, Carsten,Resnati, Giuseppe,Terraneo, Giancarlo,Wainwright, Stephen G.,Whitwood, Adrian C.
supporting information; experimental part, p. 9511 - 9524 (2010/12/20)
New liquid-crystalline materials were prepared by self-assembly driven by halogen bonding between a range of 4-alkoxystilbazoles, 4-alkyl-, and 4-alkoxy-substituted pyridines as halogen-bonding acceptors, and substituted derivatives of4-iodotetrafluorophenyl as halogen-bonding donors. Despite the fact that the starting materials are not mesomorphic, the dimeric, halogen-bonded complexes obtained exhibited nemetic and SmA phases, depending on the length of the alkylchains present on the components. The modularity of this approach also led to new chiral mesogens starting from non-mesomorphic chiral compounds.
Novel hydroxy- and methyl-terminated triaromatic schiff base compounds: Synthesis and mesogenic properties
Senthilkumar, Natarajan,Narasimhaswamy, Tanneru,Raghavan, Aravamudhan
experimental part, p. 276 - 285 (2011/06/19)
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.
Hydrogen-bond induced side-chain liquid crystalline polymers based on nicotinic acid derivatives
Saravanan,Ambili,Kannan
experimental part, p. 217 - 222 (2011/10/18)
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.
Synthesis of 4-[(1R,4R)-3-oxo-p-menthan-2-ylidenemethyl]benzoic acid and its esters
Drushlyak,Kutulya,Pivnenko,Vashchenko
, p. 622 - 627 (2007/10/03)
Carbonylation of (E)-2-(4-halobenzylidene)-p-menthan-3-ones, catalyzed by PdCl2(PPh3)2, gave a distereometric mixure of 4-[(1R,4R)- and (1R,4S)-3-oxo-p-menthan-2-ylidenemethyl]benzoic acids, whose reaction with phenols gave 1R,4R diastereomers of the corresponding esters. 2005 Pleiades Publishing, Inc.
