35108-00-0Relevant articles and documents
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.
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.
