Chiral Nanotubes

Organic nanotubes, as assembled nanospaces, in which to carry out host–guest chemistry, reversible binding of smaller species for transport, sensing, storage or chemical transformation purposes, are currently attracting substantial interest, both as biological ion channel mimics, or for addressing tailored material properties. Nature’s materials and machinery are universally asymmetric, and, for chemical entities, controlled asymmetry comes from chirality. Together with carbon nanotubes, conformationally stable molecular building blocks and macrocycles have been used for the realization of organic nanotubes, by means of their assembly in the third dimension. In both cases, chiral properties have started to be fully exploited to date. In this paper, we review recent exciting developments in the synthesis and assembly of chiral nanotubes, and of their functional properties. This review will include examples of either molecule-based or macrocycle-based systems, and will try and rationalize the supramolecular interactions at play for the three-dimensional (3D) assembly of the nanoscale architectures

Polylactic-Containing Hyperbranched Polymers through the CuAAC Polymerization of Aromatic AB₂ Monomers

We report on the synthesis and characterization of a novel class of hyperbranched polymers, in which a copper(I)-catalyzed alkyne azide cycloaddition (CuAAC) reaction (the prototypical “click” reaction) is used as the polymerization step. The AB2 monomers bear two azide functionalities and one alkyne functionality, which have been installed onto a 1,3,5 trisubstituted benzene aromatic skeleton. This synthesis has been optimized in terms of its purification strategies, with an eye on its scalability for the potential industrial applications of hyperbranched polymers as viscosity modifiers. By taking advantage of the modularity of the synthesis, we have been able to install short polylactic acid fragments as the spacing units between the complementary reactive azide and alkyne functionalities, aiming to introduce elements of biodegradability into the final products. The hyperbranched polymers have been obtained with good molecular weights and degrees of polymerization and branching, testifying to the effectiveness of the synthetic design. Simple experiments on glass surfaces have highlighted the possibility of conducting the polymerizations and the formation of the hyperbranched polymers directly in thin films at room temperature

Clickable 2,2-bis(hydroxymethyl)propionic acid-derived AB2 monomers: Hyperbranched polyesters through the CuAAC cycloaddition (click) reaction

AbstractWe present the synthesis and characterization of two aliphatic AB2 monomers derived from the readily available 2,2‐bis(hydroxymethyl)propionic acid and containing one alkyne group and two azide functionalities. The distance between the polymerizable groups differs in the two monomers by the insertion of an additional carbon atom in the aliphatic structure that addresses the steric demand during polymerization. The synthetic procedure for the monomers is relatively simple and scalable, and the monomers are able to polymerize through the Copper(I)‐catalyzed Azide‐Alkyne Cycloaddition (CuAAC reaction). The polymerization affords hyperbranched polymers in good yields and molecular weights and moderate degrees of branching. Copyright © 2021 John Wiley & Sons, Ltd

Cross-talk between endogenous H2S and NO accounts for vascular protective activity of the metal-nonoate Zn(PipNONO)Cl

Nitric oxide (NO) and hydrogen sulfide (H2S) are now recognized as gaseous transmitters with many cardiovascular protective properties. The present study concerns the possibility that NO donors can also function through endogenous activation of NO and H2S pathways. Based on the previous characterization of a novel metal-nonoate, Ni(PipNONO)Cl, our aim was: 1) to study the effects of a zinc based compound, Zn(PipNONO)Cl, on vascular endothelial and smooth muscle cells, and 2) to assess the role and interplay between endogenous NO and H2S promoted by the nonoate. Zn(PipNONO)Cl completely reproduced the vasodilation elicited by Ni(PipNONO)Cl. In the presence of endothelium, preincubation with Zn(PipNONO)Cl sensitized the intima to acetylcholine-induced vasodilation. When tested on cultured endothelial cells, Zn(PipNONO)Cl promptedPI-3K/Akt- and MAPK/ERK1/2-mediated survival. Nitrite levels indicated fast NO release (due to the molecule) and delayed (1-6 h) NO production linked to PI-3K/Akt-dependent eNOS activation. In the same time frame (1-6 h), significant CSE-dependent H2S levels were detected in response to Zn(PipNONO)Cl. The mechanisms responsible for H2S increase seemed to depend on the NONO moiety/sGC/cGMP pathway and zinc-associated ROS production. Our results indicate that endogenous H2S and NO were produced after fast NO release from Zn(PipNONO)Cl, contributing to the vascular endothelium protective effect. The effect was partially reproduced on smooth muscle cells, where Zn(PipNONO)Cl inhibited cell proliferation and migration. In conclusion, vasorelaxant effects, with complementary activities on endothelium and smooth muscle cells, are elicited by the novel metal-nonoate Zn(PipNONO)Cl

Anti-hypertensive property of a nickel-piperazine/NO donor in spontaneously hypertensive rats

7noreservedThe nickel-piperazine/NO donor compound, Ni(PipNONO)Cl, belonging to the family of compounds labelled as "metal-nonoates", due to its promising vasodilating activity, has been considered as a potential drug candidate in anti-hypertensive therapy. Drug efficacy has been evaluated in spontaneously hypertensive rats (SHR) in comparison with normotensive animals (C57BL/6 mice and WKY rats). In normotensive animals the metal-nonoate maintained blood pressure at basal level both following acute administration and after 30 days of treatment. In SHR, Ni(PipNONO)Cl reduced blood pressure in the dose range of 3-10 mg/kg. When compared with a commercial NONOate, DETA/NO, used at the same doses, Ni(PipNONO)Cl was more active in reducing blood pressure in SHR than DETA/NO in the first two weeks, while the effect of the two molecules was similar in the third and fourth week. The degradation and control compound Ni(Pip)Cl2 had no effect on blood pressure and heart rate in same animal models. Remarkably, the blood pressure reduction induced by the new NO-donor Ni(PipNONO)Cl does not evoke changes in the heart rate and tolerance. Considering the mechanisms of vascular protection, 30 days of administration of Ni(PipNONO)Cl improved endothelial function in SHR by upregulating endothelial NO synthase (eNOS) through increased eNOS protein levels and downregulated Caveolin-1 (Cav-1), and by increasing superoxide dismutase 1 (SOD1) protein level in aortae. In cultured endothelial cells Ni(PipNONO)Cl restored the cell functions (cytoskeletal protein expression, migration and proliferation) altered by the inflammatory mediator interleukin-1β (IL-1β), impairing the endothelial to mesenchimal transition. In conclusion, Ni(PipNONO)Cl maintained unaltered blood pressure in normotensive mice and rats, and it exerted anti-hypertensive effect in SHR through the restoration of vascular endothelial protective functions.mixedMonti, Martina; Ciccone, Valerio; Pacini, Aurora; Roggeri, Riccardo; Monzani, Enrico; Casella, Luigi; Morbidelli, LuciaMonti, Martina; Ciccone, Valerio; Pacini, Aurora; Roggeri, Riccardo; Monzani, Enrico; Casella, Luigi; Morbidelli, Luci

Impact damage characteristics of carbon-epoxy composites

SIGLEAvailable from British Library Document Supply Centre- DSC:DX174823 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

“Clickable” bacterial poly(gamma-glutamic acid)

Poly(gamma-glutamic acid) (gamma-PGA) is one of the few bacterial polymers in nature; as such, it possesses the added value of a “green birth” (fermentation) and “green death” (biodegradability), which is ideal for sustainable macromolecular platforms. Efficient functionalization strategies are required in order to transform the native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications. We report on a novel approach to the facile functionalization of bacterial gamma-PGA, realized with several levels of control: (a) the modulation of the molecular weight through sonication, and the solubilization in organic solvents through counterion exchange with suitable quaternary ammonium salts, (b) the introduction of reactive functionalities through reactions in homogeneous conditions in organic solvents, to afford homo- or copolymers; (c) a second tier functionalization using copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) click chemistry.Peer ReviewedPostprint (published version

Structure–activity relationship for the solid state emission of a new family of “push–pull” π-extended chromophores

We report the design, synthesis, molecular optical properties, and solid state emissive behaviour of a series of novel compounds, which, similar to the archetypal AIE luminogen tetraphenylethene, are formed of a central olefin stator and decorated with either three or four rotors. These rotors, being either electron-rich substituted benzenes, or electron-withdrawing functional groups (esters, ketones, cyano groups) confer a "push-pull" character to the overall molecular structure. Building on both new and already published contributions, a comprehensive picture of the properties and the potential of these compounds is provided

Poly(gamma-glutamic acid) esters with reactive functional groups suitable for orthogonal conjugation strategies

We report on a series of novel poly(c-glutamic acid) (PGGA) esters, in which the chemical structure and composition, and the molecular weight are systematically changed. Modification of PGGA of microbial origin, used either as the sodium salt or in the free acid form, by means of alkylation with highly reactive bromides under SN2 conditions, affords copolymers with an essentially random microstructure. These reaction conditions are applied iteratively to achieve full esterification, obtaining allyl or propargyl ester functionalities within the polymer backbone, diluted with inert functional groups, such as benzyl, ethyl, or hexyl ester functionalities. The copolymers have been characterized regarding their chemical structure and thermal and bulk properties using nuclear magnetic resonance, thermogravimetry, differential scanning calorimetry, and X-ray diffraction techniques. We demonstrate that allyl and propargyl ester groups can be efficiently transformed using click chemistries, such as thiol-ene or copper(I)- catalyzed azide–alkyne cycloaddition reactions; such efficient conjugation strategies will be required to transformthe native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications.Peer Reviewe