Supported catalysis is emerging as a cornerstone of transition metal catalysis, environmental awareness necessitates "green" methodologies and resources become scarcer more expensive. Although these supported systems are quite useful, especially in their capacity for catalyst recycling recovery, higher activity selectivity have been elusive compared with nonsupported catalysts. This Account describes recent developments polymer-supported metal-salen complexes, which often surpass analogues...

Negative beats positive: A channel composed of oligoether chains attached by amine groups to β-cyclodextrin mediates the transport halides across a phospholipid bilayer (see scheme) at faster rates than those observed for monovalent cations. Protonation linkages likely explains preferential anion transport. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z501625_s.pdf or from author. Please note: The publisher not responsible...

Cytochrome P450 (CYP) family of redox enzymes metabolize drugs and xenobiotics in liver microsomes. Isozyme CYP2C9 is reported to be inhibited by benzbromarone (BzBr) this phenomenon was hitherto explained classical active-site binding. Theoretically, it impossible envisage the experimentally derived sub-nM Ki for an inhibitor, when supra-nM enzyme 10X KM substrate concentrations were employed. We set out find a more plausible explanation highly intriguing "super-inhibition" phenomenon. In...

Anion transporters play a vital role in cellular processes and their dysregulation leads to range of diseases such as cystic fibrosis, Bartter's syndrome epilepsy. Synthetic chloride are known induce apoptosis cancer cell lines. Herein, we report triamide macrocycles that easily synthesized externally functionalized by pendant membrane-permeable groups. Among variety chains appended onto the macrocycle scaffold, cholesterol is found be best with an EC50 value 0.44 μM. The highly...

Abstract In this contribution, we describe polymer‐supported ( R,R )‐(salen)AlCl complexes that were immobilized on poly(norbornene)s and display excellent activities enantioselectivies as catalysts for the 1,4‐conjugate addition of cyanide to α,β‐unsaturated imides. These supported could be recycled up 5 times without compromising catalyst or selectivities. Furthermore, loadings reduced from 10–15 mol%, common non‐supported (salen)Al catalysts, a decrease metal content by 50–66%, lowering...

Abstract AlCl–salen (salen= N , ′‐bis(salicylidene)ethylenediamine dianion) catalysts supported onto macrocyclic oligomeric cyclooctene through linkers of varying length and flexibility have been developed to demonstrate the importance support architecture on catalyst activity. The role played by in dictating activity was found vary for reactions with contrasting mechanisms, such as bimetallic cyanide monometallic indole addition reactions. While flexible significantly enhanced reaction,...

Ion-channel mimics are able to transmit electrical signals across phospholipid membranes, and can be envisioned as nanoswitches for molecular electronics. Here, we reported the use of pH alter ion-transport rates through a synthetic aminocyclodextrin ion channel. Both cation- anion-transport were found increase with an in due unique electrostatics multiple ammonium groups that line channel pore. Such regulation transport is exploited sensing applications.

Poly(norbornene) supports comprising solubilizing ethylene glycol units and multiple amino acid attachment sites have been developed for peptide synthesis. A variety of acids efficiently loaded (0.6–1.1 mmol/g) onto the support in high yields (83–98%). Several tripeptides synthesized moderate-to-good overall (41–66%) using only 1.2 equiv coupling reagents/amino acids, could be recycled up to 3 times.

Abstract Protein pores that selectively transport ions across membranes are among nature’s most efficient machines. The selectivity of these can be exploited for ion sensing and water purification. Since it is difficult to reconstitute membrane proteins in their active form practical applications desirable develop robust synthetic compounds cell membranes. One envision tuning the by incorporating functional groups inside pore. Readily accessible octapeptides containing (aminomethyl)benzoic...

Solid-phase peptide synthesis has been an attractive method for synthesizing peptides because it is quick and can be automated. The heterogeneous reaction medium in solid-phase necessitates the use of large equivalents reagents to drive reactions completion. Peptide using soluble, yet isolable, supports alternative synthesis. Reported herein a soluble poly(norbornene)-derived support containing multiple attachment sites high loading capacities solubilizing oligoether/alkyl groups....

ABSTRACT The conversion of polymeric waste into useful, value added material is considered as an efficient method for management because the environmental issues caused by such materials. This work proposes a simple, cost‐effective strategy expanded polystyrene nanoparticles via nanoprecipitation. In this method, dissolved in suitable solvent example, tetrahydrofuran and to nonsolvent, water, precipitate diameter less than 500 nm. study also investigates influence various process parameters...

Negativ schlägt positiv: Ein Kanal aus Oligoetherketten, die über Amingruppen an β-Cyclodextrin gebunden sind, vermittelt den Transport von Halogeniden durch eine Phospholipiddoppelschicht (siehe Schema) mit Geschwindigkeiten, für einwertige Kationen überschreiten. Eine Protonierung der Aminverknüpfungen erklärt vermutlich bevorzugten Anionentransport. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2005/z501625_s.pdf or from...

A detailed experimental study on flame spread over non-uniform ports of solid propellant rockets has been carried out. An idealised. 2-dimensional laboratory motor was used for the with aid cinephotography. Freshly prepared rectangular HTPB backward facing step as specimenfor this study. It shown conclusively that under certain conditions location. height and port which govern velocity gases at by partially ignited surface. secondary ignition may occur far downstream step. This is very...

Ion transporters have been developed from acyclic octapeptides comprising L/D alanine and m-aminobenzoic acid. These transport cations up to 3 times faster than their cyclic analog through lipid vesicles. Preliminary CD, XRD computational studies allude a 6–9 Å wide tetrameric ion channel as the active transporter.

A pyridine containing triamide macrocycle and its substituted analog have been synthesized in one pot from the corresponding monomer without use of coupling reagents. The can selectively bind chloride ions. ease synthesis chloride-binding properties make it a highly attractive scaffold for ion-encapsulation, ion-transport water purification.

Synthetic pores that selectively transport ions of biological significance through membranes could be potentially used in medical diagnostics or therapeutics. Herein, we report cation-selective octapeptide derived from alanine and aminopicolinic acid. The ion mechanism the has been established to a cation-chloride symport. co-transport is biologically essential for efficient functioning central nervous system implicated diseases such as epilepsy. formed synthetic lipid bilayers do not...

Transmembrane ion-pair co-transport using synthetic transporters is non-trivial. Herein, cyclic dipeptide ion-carriers with dangling ester motifs to bind cations and amide-NH anions are reported. The pendant lipophilic norbornene units aid in membrane insertion achieve MCl this simple design.

Single molecules that co-transport cations as well anions across lipid membranes are few despite their high biological utility. The elegant yet simple lipidomimmetic peptide design herein enables efficient HCl transport without the use of any external additives for proton transport. carboxylic acids in dipeptide scaffold provide a handle to append two long hydrophobic tails and also polar hydrophilic carboxylate group. central unit provides NH sites anion binding. Protonation group coupled...

Abstract Natural ion‐transporters in cellular membranes play a critical role maintaining cell homeostasis. Synthetic are attractive model systems for understanding and addressing dysfunction of natural transporters. Herein, simple amide derived from azobenzene m ‐aminobenzoic acid achieves photoregulated ion transport across lipid membranes. The forms pores or channels that selectively co‐transport H + /X − the membrane. Photoisomerization trans to cis form results 2‐fold increase...

The synthesis of peptide drugs has become facile with the use supports that enable easy separation growing peptide. Peptide on insoluble typically employs excess reagents to enhance reaction efficiency and faces challenges during intramolecular cyclization. A non‐crosslinked soluble polystyrene support is reported herein improves cyclization by using spacers. illustrated synthesizing octreotide drug in a scalable manner on‐support methodology drastically reduces reagent waste, raw‐material...

Functionalized pores that are stable to chemical degradation attractive for use in a variety of applications ranging from sensing catalysis. Herein, robust polymer nanotube bundles decorated with carboxylate groups inside the have been developed two steps cyclic peptide template containing polymerizable norbornene units. The forms ca. 35 nm diameter. Polymerization exposed units gives peptide–polymer hybrid 100 diameter improved thermal and stability compared nanotubes. Hydrolysis ester...