15442-91-8Relevant articles and documents
N-Spirocyclic Quaternary Ammonium Ionenes for Anion-Exchange Membranes
Pham, Thanh Huong,Olsson, Joel S.,Jannasch, Patric
, p. 2888 - 2891 (2017)
The development of cationic polymers for anion-exchange membranes (AEMs) with high alkaline stability and conductivity is a considerable challenge in materials chemistry. In response, we here present the synthesis and properties of N-spirocyclic quaternary ammonium ionenes (spiro-ionenes) containing 5- and 6-membered rings fused by central nitrogen cations. High-molecular weight and film-forming spiro-ionenes are successfully synthesized in cyclo-polycondensations of tetrakis(bromomethyl)benzene and dipiperidines under mild conditions. These polyelectrolytes show excellent thermal and alkaline stability with no degradation detected by NMR spectroscopy after more than 1800 h in 1 M KOD/D2O at 80 °C. Even at 120 °C, the spiro-ionenes display reasonable alkaline stability. Transparent and mechanically robust AEMs based on ionically cross-linked blends of spiro-ionene and polybenzimidazole reach OH- conductivities up to 0.12 S cm-1 at 90 °C. The current findings demonstrate that spiro-ionenes constitute a new class of alkali-stable anion-exchange polymers and membranes.
1,2,4,5-Tetrakis(trimethylsilylmethyl)-benzene at 150 K
Nagel, Norbert,Ansari, Manssur,Bock, Hans
, p. 1329 - 1331 (1997)
The title compound, C22H46Si4, crystallizes in space group Fddd with crystallographic symmetry 222. Steric overcrowding by the bulky ligands is avoided by arranging the trimethylsilyl groups alternately above and below the benzene plane in skeletal D2 symmetry.
Secondary interactions in bromomethyl-substituted benzenes: Crystal structures of three α,α′-bis-bromoxylenes, 1,2,3,5-tetrakis(bromomethyl)benzene, and 1,2,4,5-tetrakis(bromomethyl)benzene
Jones, Peter G.,Ku?, Piotr
, p. 725 - 731 (2007)
X-Ray structure determinations of all three isomers of bis(bromomethyl) benzene and of two isomeric tetrakis(bromomethyl)benzenes show that the packing of the molecules is determined principally by interactions of the bromomethyl groups (C-H ? Br and Br ? Br), except for ortho-bis (bromomethyl)benzene, in which C-H ? π interactions play a major role.
Tuning Intrinsic and Extrinsic Proton Conduction in Metal-Organic Frameworks by the Lanthanide Contraction
Wong, Norman E.,Ramaswamy, Padmini,Lee, Andrew S.,Gelfand, Benjamin S.,Bladek, Kamila J.,Taylor, Jared M.,Spasyuk, Denis M.,Shimizu, George K.H.
supporting information, p. 14676 - 14683 (2017/10/24)
Seven isomorphous lanthanide metal-organic frameworks in the PCMOF-5 family, [Ln(H5L)(H2O)n](H2O) (L = 1,2,4,5-tetrakis(phosphonomethyl)benzene, Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) have been synthesized and characterized. This family contains 1-D water-filled channels lined with free hydrogen phosphonate groups and gives a very low activation energy pathway for proton transfer. The lanthanide contraction was employed to systematically vary the unit cell dimensions and tune the proton conducting pathways. LeBail fitting of the crystalline series shows that the crystallographic a-axis, along the channel, can be varied in increments less than 0.02 ? correspondingly shortening the proton transfer pathway. The proton conductivities for the La and Pr complexes were roughly an order of magnitude higher than other members of the series (10-3 S cm-1 versus 10-4 S cm-1). Single crystal structures of the high and low conducting members of the series (La, Pr for high and Ce for low) affirm the structural similarities extend beyond the unit cell parameters to positions of free acid groups and included water molecules. Scanning electron microscopy reveals marked differences in particle size of the different members of the Ln series owing to lattice strain effects induced by changing the lanthanide. Notably, the high conducting La and Pr complexes have the largest particle sizes. This result contradicts any notion that degradation of the MOF at grain boundaries is enabling the observed conductivity as proton conduction dominated by extrinsic pathways would be enabled by small particles (i.e., the La and Pr complexes would be the worst conductors). Proton conductivity measurements of a ball milled sample of the La complex corroborate this result.
Diversity oriented approach to oxepine derivatives: further expansion via diels?Alder reaction
Kotha, Sambasivarao,Ali, Rashid
, p. 645 - 658 (2015/03/04)
Oxepine derivatives have been assembled via Diels?Alder (DA) reaction as a key step and the latent dienes suitable for the DA reaction have been generated in situ from the sultine derivatives, which in turn were achieved by using commercially available rongalite. The "drug like" molecules assembled here may find useful applications in medicinal as well as bioorganic chemistry.
