29147-92-0Relevant academic research and scientific papers
Organic functionalisation of graphene catalysed by ferric perchlorate
Yang, Lei,He, Junpo
, p. 15722 - 15725 (2014)
We have developed a method to prepare covalently functionalised graphene using ferric perchlorate as the catalyst. The resulting functionalised graphene was characterised by Raman spectroscopy, TGA, XPS, AFM, and dispersibility tests in organic or aqueous
Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
, p. 2545 - 2555 (2021/02/01)
Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
Highly luminescent liquid crystals by connecting 1,3,4-oxadiazole with thiazolo[5,4-d]thiazole units
Bechtold, Ivan H.,Cazati, Thiago,Curcio, Sergio F.,Eccher, Juliana,Falc?o, Eduardo H. L.,Farias, Giliandro,Gallardo, Hugo,Girotto, Edivandro,Malvestiti, Ivani,Manfredi, Alex M.,Salla, Cristian A. M.,Santos, Arthur B. S.,Westphal, Eduard
, (2020/12/17)
The direct bonding between a thiazolo[5,4-d]thiazole and two 1,3,4-oxadiazole units allowed us to create a new and versatile rigid core for luminescent liquid crystal, which showed interesting and variable mesomorphic and photophysical properties. From the 5-bis(5-phenyl-1,3,4-oxadiazol-2-yl)thiazolo[5,4-d]thiazole new core, three molecules with different number of alkoxy chains were synthesized and had their properties correlated with the molecular structure. The molecule with two chains showed a smectic C mesophase, while the mesogens with four and six chains presented hexagonal columnar mesomorphism, which was confirmed by POM and XRD measurements. In addition, the molecule with six chains presented liquid crystalline behavior close to room temperature. In solution, the molecules presented strong photoluminescence ranging from blue to yellow, with quantum yields higher than 0.6. Excited state lifetimes allowed to correlate the fluorescence component associated to the different emitting species to the molecular organization in spin coated films. The molecular energy levels, together with thermal stability and possible charge carrier transport due to molecular packing, suggest that these molecules are promising for optoelectronic applications. Overall, this work contributes to the development of the use of thiazolo[5,4-d]thiazole in liquid crystals, demonstrating its great efficiency and versatility.
Amphiphile self-assembly dynamics at the solution-solid interface reveal asymmetry in head/tail desorption
Castillo, Henry D.,Espinosa-Duran, John M.,Dobscha, James R.,Ashley, Daniel C.,Debnath, Sibali,Hirsch, Brandon E.,Schrecke, Samantha R.,Baik, Mu-Hyun,Ortoleva, Peter J.,Raghavachari, Krishnan,Flood, Amar H.,Tait, Steven L.
supporting information, p. 10076 - 10079 (2018/09/13)
Amphiphilic alkoxybenzonitriles (ABNs) of varying chain length are studied at the solution/graphite interface to analyze dynamics of assembly. Competitive self-assembly between ABNs and alkanoic acid solvent is shown by scanning tunneling microscopy (STM)
H-bonded complexes containing 1,3,4-oxadiazole derivatives: Mesomorphic behaviour, photophysical properties and chiral photoinduction
Vieira, Andre A.,Cavero, Emma,Romero, Pilar,Gallardo, Hugo,Serrano, Jose Luis,Sierra, Teresa
supporting information, p. 7029 - 7038 (2014/08/18)
Two series of new V-shaped acids derived from 1,3,4-oxadiazoles are described. These acids were used to prepare supramolecular complexes through hydrogen bonding with 2,4-diamino-6-dodecylamino-1,3,5-triazine in a 3:1 ratio, respectively. The formation of the complexes was studied by infrared and NMR techniques. The thermal behaviour and mesomorphic properties of all the complexes were investigated by polarized light optical microscopy, differential scanning calorimetry and X-ray diffraction. Hexagonal and rectangular columnar mesophases were observed for all complexes at room temperature, without evidence of crystallization. The results of circular dichroism studies allowed us to propose that in the liquid crystalline state these materials adopt a helical columnar organization and this chirality can be controlled by irradiation with CPL. Furthermore, the complexes display strong blue luminescence in solution and in the mesophase. the Partner Organisations 2014.
Columnar mesomorphism of bent-rod mesogens containing 1,2,4-oxadiazole rings
Gallardo, Hugo,Ferreira, Marli,Vieira, André A.,Westphal, Eduard,Molin, Fernando,Eccher, Juliana,Bechtold, Ivan H.
experimental part, p. 9491 - 9499 (2011/12/15)
In this study, the synthesis, characterization, and mesomorphic properties of ten new bent-rod compounds containing two units of 1,2,4-oxadiazoles are reported. In order to understand the relationship between the structure and the mesomorphic behavior, molecules containing a variety of polar substituents (i.e., I, NO2, NH2, OH) on the central rigid core were prepared. The hexagonal columnar mesomorphism was characterized by DSC and POM and the nature of the mesophases was established through XRD studies. The driving force for self-assembly can be explained by microsegregation between the aliphatic parts and the polar parts, producing a dimer, trimer, and tetramer inside a single disc.
Utilization of evaporation during the crystallization process: Self-templation of organic parallelogrammatic pipes
Seo, Myungeun,Kim, Jung Hak,Seo, Gon,Shin, Chae-Ho,Kim, Sang Youl
experimental part, p. 612 - 622 (2009/06/20)
Analogues of 4-dodecyloxy-2-trifluoromethylbenzamide (12FH2) consisting of a hydrophobic alkyl chain, a trifluoromethylated aromatic ring, and a self-complementary hydrogenbonding amido group were synthesized, and the structural effect of each component o
Highly symmetric 2D rhombic nanoporous networks arising from low symmetry amphiphiles
Ahn, Seokhoon,Morrison, Christine N.,Matzger, Adam J.
supporting information; experimental part, p. 7946 - 7947 (2009/12/02)
(Figure Presented) Highly symmetric 2D nanoporous molecular networks containing rhombic voids are demonstrated to be accessible from low symmetry amphiphilic molecules. The amide amphiphiles overcome the barrier to symmetry generation in the two-dimensional crystal through forming an aggregate as a building block. This aggregate consists of three inequivalent amphiphiles that assemble to create 3- and 6-fold rotation axes through hydrogen bonding. In the 6-fold rotation axis, an unusual hydrogen bonding network, supported by high resolution scanning tunneling microscopy(STM) images and computation, is observed. This network formed by amide groups significantly contributes to constructing the rhombic nanoporous network, whereas carboxylic acid amphiphiles do not adopt this nanoporo us network due to a geometric difference of hydrogen bonding. This investigation demonstrates that a high symmetry pattern is achievable withoutcorrelation with molecular symmetry through the proper combination of n oncovalent interactions of simple amphiphilic molecules.
Naphthyridine-based helical foldamers and macrocycles: Synthesis, cation binding, and supramolecular assemblies
Petitjean, Anne,Cuccia, Louis A.,Schmutz, Marc,Lehn, Jean-Marie
, p. 2481 - 2495 (2008/09/19)
(Figure Presented) Unraveling the factors that control the conformation of molecular chains is of great interest both for understanding the shape of biological molecular strands and for designing artificial ones that adopt desired forms. Thus, a variety of artificial folding codons have been identified that enforce the formation, among others, of helices, strands, and loops, the major emphasis being on the shape of the foldamer. We report herein the synthesis and study of a family of foldamers and macrocycles based on the 1,8-naphthyridine and pyrimidine units, whose internal cavity is large enough to accommodate ionic substrates, and focus on the impact of guest binding within a cylindrical environment. Interestingly, the binding event within these large oligomers is translated to the outside of the receptors and affects the interaction of the overall complexes with the outside world. For instance, alkali cations bind to the one-turn helices and macrocycles to promote fibril formation and aggregation. Also, polyammonium substrates are able to tune the length of the overall helix assemblies and the rigidity of long oligomers. The reported data on one-turn, two-turn helices and macrocycles not only allows one to devise a model for the ion-controlled supramolecular assembly of such systems but also provides evidence that such controlled scaffolds bear promise in the design of complex systems.
Bidirectional Association of Branched Noncovalent Complexes of Tetrazoles and 1,3,5-Tris(4,5-dihydroimidazol-2-yl)benzene in Solution
Kraft, Arno,Osterod, Frank,Froehlich, Roland
, p. 6425 - 6433 (2007/10/03)
Noncovalent 3:1 complexes were obtained by combining acidic tetrazoles with the tribasic 1,3,5-tris(4,5-dihydroimidazol-2-yl)benzene (1). A branched structure and the use of solubilizing groups ensured that the resulting complexes dissolved in a range of nonpolar organic solvents. An X-ray crystal structure analysis of a model complex with tetrazole showed a completely planar, C3-symmetrical, hydrogen-bonded molecule that salt-packed along the crystallographic c axis with an interplanar spacing of 3.31 A. Model binding studies between a tetrazolate and a protonated 1,3-bis(4,5-dihydroimidazol-2-yl)benzene allowed an association constant of 2470 ± 400 M-1 to be measured in the competitive solvent mixture CDCl3/CD3OD (97:3). The ionic nature and the extended planarity of the tetrazole complexes' core favored the formation of supramolecular stacks not only in the solid, but also in (nonpolar) solution. Self-association was evidenced by NMR and CD spectroscopy as well as by vapor-pressure osmometry.
