- N-Spirocyclic Quaternary Ammonium Ionenes for Anion-Exchange Membranes
-
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.
- Pham, Thanh Huong,Olsson, Joel S.,Jannasch, Patric
-
-
Read Online
- Diversity-oriented approach to spirooxindoles: Application of a green reagent 'rongalite'
-
Abstract A range of functionalized spirooxindole derivatives have been assembled via the Diels-Alder (DA) reaction. Here, rongalite has been used to generate the key sultine building blocks which are useful latent diene equivalents in the DA chemistry. The di-bromo intermediates used here are produced by reacting the 1,2,4,5-tetrakis(bromomethyl)benzene with protected oxindole derivatives under operationally simple reaction conditions. In our study, we avoided the isolation of various intermediates, and thus reduced the cost and efforts related to the overall process.
- Kotha, Sambasivarao,Ali, Rashid
-
-
Read Online
- 1,2,4,5-Tetrakis(trimethylsilylmethyl)-benzene at 150 K
-
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.
- Nagel, Norbert,Ansari, Manssur,Bock, Hans
-
-
Read Online
- Synthesis and electrical properties of crosslinked poly(1,2,4,5-phenylenedivinylene) and copolymers
-
Crosslinked conjugated conducting polymer, poly(1,2,4,5-penylene divinylene)(PPDV) and its copolymers were prepared by the water-soluble precursor method. The spectral characteristics of these materials have been investigated by using UV-visible and FT-IR spectroscopy. PPDV hemopolymer film could not be stretched due to its crosslinked structure, so this homopolymer could slightly be duped with strong oxidant, FeCl3, to produce a very low conductivity value of 3×10-6 Scm-1. However, copolymers containing PDV units and DMPV units showed considerably high conductivities ranging from 3×10-2 to 68 Scm-1, when doped with FeCl3, depending upon the copolymer composition.
- Shim,Noh
-
-
Read Online
- 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
-
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.
- Jones, Peter G.,Ku?, Piotr
-
-
Read Online
- Catalyst-Controlled Transannular Polyketide Cyclization Cascades: Selective Folding of Macrocyclic Polyketides
-
The biomimetic synthesis of aromatic polyketides from macrocyclic substrates by means of catalyst-controlled transannular cyclization cascades is described. The macrocyclic substrates, which feature increased stability and fewer conformational states, were thereby transformed into several distinct polyketide scaffolds. The catalyst-controlled transannular cyclizations selectively led to aromatic polyketides with a defined folding and oxygenation pattern, thus emulating β-keto-processing steps of polyketide biosynthesis.
- Raps, Felix C.,F?seke, Vincent C.,H?ussinger, Daniel,Sparr, Christof
-
supporting information
p. 18390 - 18394
(2020/08/25)
-
- Tuning Intrinsic and Extrinsic Proton Conduction in Metal-Organic Frameworks by the Lanthanide Contraction
-
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.
- 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)
-
- Synthesis, structure, surface and antimicrobial properties of new oligomeric quaternary ammonium salts with aromatic spacers
-
New dimeric, trimeric and tetrameric quaternary ammonium salts were accomplished by reaction of tertiary alkyldimethyl amines with appropriate bromomethylbenzene derivatives. A series of new cationic surfactants contain different alkyl chain lengths (C4-C18), aromatic spacers and different numbers of quaternary nitrogen atoms. The structure of the products was confirmed by spectral analysis (FT-IR, 1H-NMR, 13C-NMR and 2D-NMR), mass spectroscopy (ESI-MS), elemental analysis, as well as PM5 semiempirical methods. Compound (21) was also analyzed using X-ray crystallography. Critical micelle concentration (CMC) of 1,4-bis-[N-(1-alkyl)-N,N-dimethylammoniummethyl]benzene dibromides (3-9) was determined to characterize the aggregation behavior. The antimicrobial properties of novel QACs (Quaternary Ammonium Salts) were examined to set their minimal inhibitory concentration (MIC) values against fungi Aspergillus Niger, Candida albicans, Penicillium chrysogenum and bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa.
- Brycki, Bogumil,Koziróg, Anna,Kowalczyk, Iwona,Pospieszny, Tomasz,Materna, Paulina,Marciniak, Jedrzej
-
-
- Diversity oriented approach to oxepine derivatives: further expansion via diels?Alder reaction
-
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.
- Kotha, Sambasivarao,Ali, Rashid
-
p. 645 - 658
(2015/03/04)
-
- Diversity-oriented approach to novel spirocycles via 1,2,4,5-tetrakis(bromomethyl)benzene under operationally simple reaction conditions
-
Here, we have established a simple and an efficient methodology for the synthesis of spirocyclic α-amino acids as well as spirosulfones starting with readily available active methylene compounds (AMCs). The key di-bromo building blocks were assembled by reacting various active methylene compounds with 1,2,4,5-tetrakis(bromomethyl)benzene in one step. We have also expanded this strategy to generate a variety of bis-spirocycles by treating the di-bromo intermediates with different AMCs under operationally simple reaction conditions.
- Kotha, Sambasivarao,Ali, Rashid
-
p. 6944 - 6955
(2015/08/24)
-
- A cascade Aza-Cope/Aza-prins cyclization leading to piperidine derivatives
-
The cascade aza-Cope/aza-Prins cyclization of homoallylamines to give substituted piperidines has been explored. The use of glyoxalic acid as the carbonyl component afforded bicyclic structures as a result of the internal carboxylate anion trapping the intermediate cation. The unimolecular bis-, tris-, and tetrakis(homoallylamine)s efficiently delivered the appended bis-, tris- and tetrakis(piperidine-4-ol)s (tripod and crucifix shape, respectively) as new entities. The latter compound served as an excellent ligand in the Suzuki-Miyaura cross-coupling reaction to synthesize incrustoporin. The cascade aza-Cope/aza-Prins cyclization of homoallylamines to give substituted piperidines is described. A unimolecular tetrapiperidine derivative, which resulted from this strategy, was employed as a ligand in the Suzuki-Miyaura cross-coupling reaction of an α-iodobutenolide with an arylboronic acid in an efficient synthesis of incrustoporin and its analogues.
- Nallasivam, Jothi L.,Fernandes, Rodney A.
-
p. 2012 - 2022
(2015/03/18)
-
- A water-stable metal-organic framework with highly acidic pores for proton-conducting applications
-
Metal-organic framework (MOF) materials are a nontraditional route to ion conductors, but their crystallinity can give insight into molecular-level transport mechanisms. However, some MOFs can be structurally compromised in humid environments. A new 3D metal-organic framework, PCMOF-5, is reported which conducts protons above 10-3 S/cm at 60 C and 98% relative humidity. The MOF contains free phosphonic acid groups, shows high humidity stability, and resists swelling in the presence of hydration. Channels filled with crystallographically located water and acidic groups are also observed.
- Taylor, Jared M.,Dawson, Karl W.,Shimizu, George K. H.
-
supporting information
p. 1193 - 1196
(2013/03/28)
-
- Three's company: Co-crystallization of a self-assembled S4 metallacyclophane with two diastereomeric metallacycle intermediates
-
Three discrete supramolecular self-assembled arsenic(iii) complexes including an unusual S4-symmetric tetranuclear [As4L 2Cl4] metallacyclophane and two diastereomeric cis/trans-[As2LCl2] metallacycle intermediates co-crystallize within a single crystal lattice.
- Lindquist, Nathan R.,Carter, Timothy G.,Cangelosi, Virginia M.,Zakharov, Lev N.,Johnson, Darren W.
-
supporting information; experimental part
p. 3505 - 3507
(2010/08/06)
-
- Luminescent amphiphilic dendrimers with oligo(p-phenylene vinylene) core branches and oligo(ethylene oxide) terminal chains: Syntheses and stimuli-responsive properties
-
A class of new dendrimers consisting of hydrophobic oligo(p-phenylene vinylene) core branches and hydrophilic oligo(ethylene oxide) terminal chains was synthesized. These amphiphilic dendritic molecules are highly luminescent and exhibit critical micellization behaviors. They also show a lower critical solution temperature (LCST) in an aqueous medium. Both the critical micelle concentration (CMC) and LCST increased with increasing branch number and the ratio of the hydrophilic oligo(ethylene oxide) to hydrophobic oligo(p-phenylene vinylene) moieties. Besides, a temperature-dependent phase transition from a clear to cloudy aqueous solution was observed. The temperature-induced phase transition was also reflected by fluorescence quenching, 1H NMR resonance peak broadening, and UV-vis absorption shift arising from the hydrophobic conjugated core. These changes in the phase structure and photophysical properties were demonstrated to be highly reversible, indicating some interesting stimuli-responsive behaviors. The Royal Society of Chemistry.
- Chang, Dong Wook,Dai, Liming
-
p. 364 - 371
(2008/02/03)
-
- Dynamic covalently bonded rotaxanes cross-linked by imine bonds between the axle and ring: Inverse temperature dependence of subunit mobility
-
(Figure Presented) Building bridges: Imine bridges between the axle and ring components in rotaxanes allow simple rotaxane synthesis and a novel method for motion control to be developed. The submolecular mobility in this rotaxane-type assembly is regulated by the imine-bond formation/cleavage (see scheme). The relative abundance of the [2]rotaxane increases with decreasing temperature under dynamic equilibrium conditions.
- Kawai, Hidetoshi,Umehara, Takeshi,Fujiwara, Kenshu,Tsuji, Takashi,Suzuki, Takanori
-
p. 4281 - 4286
(2007/10/03)
-
- Synthesis and structure of a novel disulfide-containing aniline
-
A novel disulfide-containing aniline, 5,8-dihydro-1H,4H-2,3,6,7- tetrathiaanthracen-9-ylamine (6) was synthesized. The structures of the target compound and the intermediates have been identified by 1H NMR, MS, IR, Raman and elemental analysis. In addition, the structure of 9-Nitro-5,8-dihydro-1H,4H-2,3,6,7-tetrathiaanthracene (5) was determined by single X-ray analysis.
- Deng, Shi-Ren,Wu, Lei,Wang, Hao,Zhou, Bin,Li, Zao-Ying,Zhou, Yun-Hong,Wong, Wai-Kwok,Guo, Jian-Ping
-
p. 129 - 135
(2007/10/03)
-
- The synthesis of naphthosultine and benzodisultines and their pyrolysis with dienophiles: Studies on o-naphthoquinodimethane and bis-o-quinodimethane
-
Sealed tube reactions of the naphthosultine 8 with a series of electron-deficient dienophiles (fumaronitrile, N-phenylmaleimide, dimethyl fumarate, and dimethyl acetylenedicarboxylate) in toluene at 180 °C gave corresponding 1:1 cycloadducts 11-14 in various amounts along with rearranged naphthosulfolene 7 in 67-95% yields. The reaction of 1,2,4,5-tetra(bromomethyl) benzene with Rongalite (sodium formaldehyde sulfoxylate) and tetrabuty lammonium bromide in DMF gave benzodisultines 17 and 18 in a combined yield of 56%. Sealed tube reactions of benzodisultines 17 and 18 with a series of dienophiles in xylene at 200 °C gave corresponding 1:1 and 1:2 cycloadducts 20-27. The results suggested that thermal extrusion of sulfur dioxide from these sultines led to either o-naphthoquinodimethane 6 (from 8) or bis-o-quinodimethane 19 (from 17 and 18); subsequent trapping of these reactive intermediates by dienophiles and SO2 gave various 1:1 and 1:2 Diels-Alder adducts in modest to excellent yields.
- Wu, An-Tai,Liu, Wen-Dar,Chung, Wen-Sheng
-
-
- New spirans containing a 1,5-benzodithiepine system, derived from methylbenzenes. Conformational transmission
-
A synthesis of three new spirans, derived from methylbenzenes, containing the 1,5-benzodithiepine system is reported. X-ray structure proved the identity of model monospiran 9. In the solid and liquid state, the conformation of the seven-membered ring is chair, and the five-membered ring has the envelope conformation. The effect of conformational transmission in spirans 9 and 10 was observed. The synthesis of trispirans from hexamethylbenzene using the proposed scheme is also possible.
- Baranska, Joanna,Grochowski, Jacek,Jamrozik, Janusz,Serda, Pawel
-
p. 425 - 427
(2007/10/03)
-