Painting a glass slide with branched or linear N,N-dodecyl methylpolyethylenimines (PEIs) and certain other hydrophobic PEI derivatives enables it to kill influenza virus with essentially a 100% efficiency (at least a 4-log reduction in the viral titer) within minutes, as well as the airborne human pathogenic bacteria Escherichia coli and Staphylococcus aureus. For most of the coating polyions, this virucidal action is shown to be on contact, i.e., solely by the polymeric chains anchored to the slide surface; for others, a contribution of the polyion leaching from the painted surface cannot be ruled out. A relationship between the structure of the derivatized PEI and the resultant virucidal activity of the painted surface has been elucidated.bactericidal ͉ hydrophobic polyions ͉ virucidal coatings ͉ polyethylenimine ͉ flu I nfluenza virus causes one of the most prevalent human infections: in a typical year, Ϸ15% of the U.S. population is infected, resulting in up to 40,000 deaths and 200,000 hospitalizations (www.cdc.gov͞flu). Furthermore, an influenza pandemic (when a new strain of the virus, to which humans have no immunity, acquires the ability to readily infect people), assuming the estimated mortality rate of the 1918 Spanish flu pandemic (1), might kill some 75 million people worldwide.Influenza (as many other diseases) typically spreads when aerosol particles containing the virus, exhaled or otherwise emitted by an infected person, settle onto surfaces subsequently touched by others (2). Hence, this spread of infection, in principle, could be prevented if common things encountered by people are coated with ''paints'' that inactivate influenza virus.Recently, building on our prior studies with covalently derivatized surfaces (3), we discovered that certain water-insoluble, hydrophobic polycations, e.g., N,N-dodecyl methyl-polyethylenimine (PEI), when painted onto surfaces, kill bacteria on contact because of rupturing of bacterial cell membranes by erect fragments of the polycationic chains (''tentacles'') (4). Because influenza virus, belonging to a class of enveloped viruses, is protected from the outside by a lipid membrane (5, 6), we reasoned that the aforementioned hydrophobic polycations might damage it as well, thereby inactivating the virus. Indeed, in the present study we find that such painted (coated) surfaces, in addition to being extremely bactericidal, also lower the titer of the encountered influenza A virus [the most infectious type in humans (7)] at least 10,000-fold; a relationship between this virucidal activity and the coating polymer structure has been elucidated and rationalized. Results and DiscussionTo mimic a scenario whereby aerosolized aqueous droplets containing influenza virus settle onto surfaces and the virus then spreads (2), we adopted the following approach. A 10-l droplet of a PBS-buffered solution containing (1.6 Ϯ 0.3) ϫ 10 3 pfu of the A͞WSN͞33 (H1N1) strain of influenza virus was placed in the center of a 2.5 ϫ 2.5 cm glass slide (either coated or plain control). Then...
A series of novel calixpyrrole-like macrocycles, calix[n]bis(pyrrol-2-yl)benzene (calix[n]BPBs, n=2-4) 9 a-11 a, have been synthesized by means of the TFA-catalyzed condensation reaction of bis(pyrrol-2-yl)benzene 8 a with acetone. Calix[2]BPB 9 a represents an expanded version of calix[4]pyrrole in which two of the four meso bridges are replaced by benzene rings. By contrast, systems 10 a and 11 a, which bear great considerable to calixbipyrroles 2 and 3, represent higher homologues of the basic calix[n]BPB motif. Solution-phase anion binding studies, carried out by means of (1)H NMR spectroscopic titrations in [D2]dichloromethane and isothermal titration calorimetry (ITC) in 1,2-dichloroethane, reveal that 9 a binds typical small anions with substantially higher affinities than 1, even though the same number of hydrogen bonding donor groups are found in both compounds. The basic building block for 9 a, benzene dipyrrole 8 a, also displays a higher affinity for anions than the building block for 1, dimethyldipyrromethane 16. Structural studies, carried out by single-crystal X-ray diffraction analyses, are consistent with the solution-phase results and reveal that 9 a is able to stabilize complexes with chloride and nitrate in the solid state. Structures of the PF6- and NO3- complexes of 10 a were also solved as were those of the acetone adduct of 9 a and the ethyl acetate adduct of 11 a.
Bigger is better: Preliminary anion‐binding studies reveal that bipyrrole‐containing macrocycle calix[3]bipyrrole 2 binds large halide anions (for example, Br−) with affinities that are substantially enhanced relative to those of the smaller pyrrole‐containing calix[4]pyrrole 1. The complexation has been studied by 1H NMR spectroscopy, isothermal titration calorimetry, and X‐ray crystallography. In addition, the synthesis of the even larger calix[4]bipyrrole was achieved.
Heterocycles other than pyrrole, specifically bipyrrole, furan, and thiophene, have been used to construct two new, calixpyrrole-like anion receptors; binding studies, carried out by ITC in CH3CN, reveal a selectivity for "Y-shaped" anions, such as benzoate, over spherical ones, such as chloride.
Hybrid calixpyrrole systems are calixpyrrole-like macrocycles that are based on more than one type of small molecule building block. Structurally, these "mixed-breed" macrocycles differ from calixpyrroles in that some pyrrolic units in the latter are replaced by other hetereocyclic units such as furan, thiophene, bipyrrole, and bithiophene. Although several such systems have been reported in recent years, only a few have been studied as possible anion receptors. In this paper, the results of detailed anion binding studies involving several prototypic systems are reported. Taken in concert, these results highlight the fact that some hybrid systems, including compounds 2-5, display anion affinities that are considerably weaker than those of the parent system 1. On the other hand, they also show that compounds 6-8 are good receptors for "Y-shaped" anions, such as carboxylates, and that they bind these species with high affinity. These findings are strongly supported by solid-state structural studies, which reveal an interesting "cross binding mode" for the binding of carboxylate anions by the bis-thiophene, bis-pyrrole system 7.
Anion binding studies reveal that, in spite of its big size and flexible structure, calix[4]bipyrrole shows strong anion binding in general and good selectivity towards chloride anion in acetonitrile.
Größer ist besser: Untersuchungen zur Anionen‐Bindung bescheinigen dem bipyrrolhaltigen makrocyclischen Calix[3]bipyrrol 2 eine deutlich bessere Fähigkeit zur Bindung großer Halogenidionen (z. B. Br−) als dem kleineren pyrrolhaltigen Calix[4]pyrrol 1. Die Komplexierung wurde mittels 1H‐NMR‐Spektroskopie, isothermer Titrationskalorimetrie und Röntgenstrukturanalyse untersucht. Auch gelang die Synthese des noch größeren Calix[4]bipyrrols.
CalixarenesCalixarenes O 0450 Calix[2]bipyrrole[2]furan and Calix[2]bipyrrole[2]thiophene: New Pyrrolic Receptors Exhibiting a Preference for Carboxylate Anions. -(SESSLER*, J. L.; AN, D.; CHO, W.-S.; LYNCH, V.; J. Am. Chem. Soc. 125 (2003) 45, 13646-13647; Dep. Chem. Biochem., Univ. Tex., Austin, TX 78712, USA; Eng.) -Bartels 10-067
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