- Light-controllable reflection wavelength of blue phase liquid crystals doped with azobenzene-dimers
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A new series of azobenzene-dimers were synthesized and doped into the blue phase liquid crystals to broaden the temperature range of BPs. It is found that not only can the reflection wavelength of BPI be reversibly controlled but BPI can also be transform
- Chen, Xingwu,Wang, Ling,Li, Chenyue,Xiao, Jiumei,Ding, Hangjun,Liu, Xin,Zhang, Xiaoguang,He, Wanli,Yang, Huai
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supporting information
p. 10097 - 10099
(2013/10/22)
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- Tethered PProDOTs: Conformationally restricted 3,4-propylenedioxythiophene based electroactive polymers
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Herein we report a complete family of conformationally restricted PProDOT derivatives with varying alkylene tether lengths. It was found that variation of the tether length and structure of the electropolymerizable monomer was successful in the fine-tuning of the electrochemical and optical properties of the subsequent material. It was found that the band gap of the materials could be varied between 1.94 and 2.26 eV, with the "sweet spot" for obtaining the maximum electronic band gap existing at the n = 6 tether length, while maintaining low redox potentials. It was also found that these polymers exhibited stable electrochromic behavior with colors varying from blue-purple to orange in their neutral states and transmissive in their doped states. The Royal Society of Chemistry 2007.
- Walczak, Ryan M.,Cowart Jr., John S.,Reynolds, John R.
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p. 254 - 260
(2008/02/01)
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- Bis-imidazoles as molecular probes for peripheral sites of the zinc endopeptidase of botulinum neurotoxin serotype A
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Botulinum neurotoxin serotype A (BoNTA) is highly toxic, and its antidote is currently unavailable. The essential light-chain subunit of BoNTA is a zinc endopeptidase that can be used as a target for developing antidotes. However, the development of high-
- Merino, Isidro,Thompson, Jason D.,Millard, Charles B.,Schmidt, James J.,Pang, Yuan-Ping
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p. 3583 - 3591
(2007/10/03)
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- THA analogs useful as cholinesterase inhibitors
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The present invention provides cholinesterase inhibitors of general formula (I): STR1 wherein R is H or (C 1 -C 4)alkyl, Y is a linking group and Z is an alkyl or aryl group, including heteroaryl groups, and the pharmaceutically acceptable salts thereof.
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- Synthesis of alkylene linked bis-THA and alkylene linked benzyl-THA as highly potent and selective inhibitors and molecular probes of acetylcholinesterase
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An efficient and economical synthesis of a series of rationally designed novel 9,9′-(alkane-1,-ω-diyldiimino)-1,2,3,4-tetrahydroacridines (ω = 7-10) and a second series of new analogues, 9-(ω-phenylalkylamino)-1,2,3,4-tetrahydroacridines (ω = 4-10), is re
- Pang, Yuan-Ping,Hong, Feng,Quiram, Polly,Jelacic, Tanya,Brimijoin, Stephen
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p. 171 - 176
(2007/10/03)
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- Novel Ion Containing Liquid Crystals and Liquid Crystalline Main Chain Polymers Based on Trans-1,2-Bis(4-Pyridyl Ethylene) Mesogen
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Ion bearing liquid crystalline compounds based on trans-1,2-bis(4-pyridinium)ethylene were synthesized and studied.These compounds included low molecular mass analogues, twin model compounds and main chain ionomers.Most of these exhibited liquid crystallinity of the smectic type.As a general rule the introduction of charges into the mesogenic moiety increased the stability (transition temperature) of the mesophase.Large supercooling effects, broad mesophase intervals and tendency to polymorphism are common features of these ionic mesogenic compounds.In the case of twin model compounds a variety of smectic phases were observed.The nature of these was dependent on the nature of the counterion and the thermal history of the compound.Tosylate or p.toluene sulfonate counterions promoted a higher degree of order in smectic mesophases as well as higher transition tempertures compared to methylsulfonate counterions.A pronounced odd-even effect of the isotropisation temperature of the twin compounds was observed.Compounds with even numbered methylene spacers display higher transition temperatures than those with an odd spacer.Only polymers with methylsulfonate and toluenesulfonate counterions were found to exhibit both, thermotropic and lyotropic mesophases.Thermotropic mesophases were characterized as smectic mesophases of lower order (SA).The nature of lyotropic mesophases were not determined.High transition temperatures and concommitant oxydative crosslinking made the study of polymers with halogen counterions difficult.Polymers with halogen and perchlorate counterions were found fo be poorly soluble in water precluding the formation of lyotropic mesophases.The introduction of a few siloxane bonds into the flexible spacer joining the charged mesogen moieties has a dramatic effect on lowering the transition temparatures and making possible the study of mesophases up to their isotropisation temperature.Preliminary characterization of polymers with siloxane containing spacer and methylsulfonate/tosylate counterions suggest a smectic mesophase of lower order. - Keywords: Ion containing liquid crystals, liquid crystal ionomers
- Cheng, P.,Blumstein, A.,Subramanyam, S.
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- Fingerprinting a Transition-Structure Guest by a Building-Block Approach with an Incremental Series of Catalytic Hosts. Structural Requirements for Glyme and α,ω-Dimethoxyalkane Catalyses in N-Methylbutylaminolysis and Butylaminolysis of 4-Nitrophenyl Acetate in Chlorobenzene
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Glymes, H-(CH2OCH2)n-H, GLM(n), catalyze butylaminolysis of 4-nitrophenyl acetate in chlorobenzene.Values of kcat/Oxy, where Oxy is the number of oxygens in the catalyst, increase with oligomer length up to triglyme, GLM(4), and then plateau.Optimal catalysis on a per oxygen basis requires a -(CH2OCH2)4-fragment, which suggests a four-point recognition of the secondary ammonium ion of the zwitterionic tetrahedral intermediate (TI) (J.Org.Chem. 1991, 56, 2821-2826).Dissection of individual structural components and reassembly to the same structure of the complexverifies this model.The following kinetic studies of 4-nitrophenyl acetate in chlorobenzene have accomplished the task: (a) methylbutylaminolysis catalyzed by GLM(n), n = 2-4; (b) methylbutylaminolysis catalyzed by α,ω-dimethoxyalkanes, CH3O-(CH2)n-OCH3, DME(n), n = 2-10 and 12; and (c) butylaminolysis catalyzed by DME(n), n = 2-10 and 12.Experiment a has revealed that kcat/Oxy is the same for GLM(2) - GLM(4).Optimal catalysis for breakdown of a zwitterionic TI with one ammonium proton only requires a -(CH2OCH2)2-fragment.Experiment b has shown that kcat/Oxy is largest for DME(2) with the values for the remaining DMEs 2 - 2.5-fold lower.A -CH2CH2- is the best spacer between the two oxygens.Thus, bifurcated hydrogen-bond formation between the two oxygens and the one ammonium proton enhances catalysis.Experiment c has revealed that kcat/Oxy for DME(2) exceeds the remaining DMEs by 3 - 3.6-fold, except for DME(8) and DME(10), which have values of kcat/Oxy only 1.7-fold slower.DME(8), the carba analogue of GLM(4), likely binds the two ammonium protons individually with the two oxygens.DME(10) behaves similarly.GLM(4) catalysis of butylaminolysis identifies -(CH2OCH2)4- as an optimal size.DME(8) catalysis confirms this size, although the two catalysts stabilize the two-proton ammonium ion differently.GLM(4) catalyzes butylaminolysis by forming two bifurcated hydrogen bonds.This suggested structure defines the size of the ammonium ion, which agrees with X-ray structural studies of polyether-ammonium complexes.Mechanistic proposals of butylaminolysis of aryl esters require such an ion.The results of this study confirm the stucture of the ion in the rate-limiting step.This building-block approach is a method for "fingerprinting" ammonium ions in transition structures of ionogenic reactions.
- Hogan, John C.,Gandour, Richard D.
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