The Effects of Structural Alterations in the Polyamine and Amino Acid Moieties of Philanthotoxins on Nicotinic Acetylcholine Receptor Inhibition in the Locust, Schistocerca gregaria

Alterations in the polyamine and amino acid (tyrosine) moieties of philanthotoxin-343 (PhTX-343) were investigated for their effects on the antagonism of nicotinic acetylcholine receptors (nAChRs) isolated from the locust (Schistocerca gregaria) mushroom body. Through whole-cell patch-clamp recordings, the philanthotoxin analogues in this study were shown to cause inhibition of the inward current when co-applied with acetylcholine (ACh). PhTX-343 (IC50 = 0.80 μM at −75 mV) antagonised locust nAChRs in a use-dependent manner, suggesting that it acts as an open-channel blocker. The analogue in which both the secondary amine functionalities were replaced with methylene groups (i.e., PhTX-12) was ~6-fold more potent (IC50 (half-maximal inhibitory concentration) = 0.13 μM at −75 mV) than PhTX-343. The analogue containing cyclohexylalanine as a substitute for the tyrosine moiety of PhTX-343 (i.e., Cha-PhTX-343) was also more potent (IC50 = 0.44 μM at −75 mV). A combination of both alterations to PhTX-343 generated the most potent analogue, i.e., Cha-PhTX-12 (IC50 = 1.71 nM at −75 mV). Modulation by PhTX-343 and Cha-PhTX-343 fell into two distinct groups, indicating the presence of two pharmacologically distinct nAChR groups in the locust mushroom body. In the first group, all concentrations of PhTX-343 and Cha-PhTX-343 inhibited responses to ACh. In the second group, application of PhTX-343 or Cha-PhTX-343 at concentrations ≤100 nM caused potentiation, while concentrations ≥1 μM inhibited responses to ACh. Cha-PhTX-12 may have potential to be developed into insecticidal compounds with a novel mode of action.

Microbial Biotextiles for a Circular Materials Economy

Harnessing microbial biofabrication and inspired by indigenous practices, we engineer high-performance microbial nanocellulose (MC) biotextiles with a sustainable circular life cycle. Specifically, our plant-based lecithin phosphocholine treatment modulates cellulose cross-linking through phosphate and methylene groups, to yield a biodegradable material with superior mechanical and flame-retardant properties. Coloration is achieved using natural dyes and waste-to-resource strategies. Life cycle impact assessment reveals MC biotextiles mitigate the carcinogenics of leather by a factor of 103 and the carbon footprint of synthetic leather and cotton by ~97%, for widespread application in fashion, interiors, and construction. The translational potential of this approach is tremendous, as using microbes and green chemistry to engineer regenerative, high-performance products will disrupt linear production models and mitigate its environmental threats in a circular economy.

Indole Hydrazide Derivatives as Potential Corrosion Inhibitors for Mild Steel in HCl Acid Medium: Experimental Study and Theoretical Calculations

The present work highlights the corrosion inhibition action of two indole-3-hydrazides with varying alkyl chain lengths: 2-(1H-indol-3-yl)acetohydrazide (IAH) and 4-(1H-indol-3-yl)butanehydrazide (IBH) against mild steel (MS) in 0.5 M hydrochloric acid (HCl) solution using electrochemical and gravimetric measurement methods. Both IAH and IBH behaved as mixed-type inhibitors, and their anticorrosion behaviour was due to a protective film formation on MS surface through physisorption, in agreement with Langmuir’s adsorption model. The surface morphologies of the inhibited specimens examined using SEM and AFM images showed distinctive improvement against acid corrosion. The quantum mechanical calculations indicated the contribution of delocalized π-electrons in the indole unit and the lone-pair electrons in the carbonyl group for improved adsorption of the studied hydrazides onto the metal surface, supporting the experimental results. IAH and IBH showed maximum inhibition efficiency of 80.4 and 94.1% at 30 °C in MS exposed to 0.5 M HCl medium at its optimum concentration. The better resistance to MS corrosion was exhibited by the acid system-containing IBH bearing three methylene groups and hence having higher molar volume and surface coverage in comparison with IAH that incorporated only one methylene group in its chemical structure.

Hydroxyl-containing bis(sulfonates). Reaction of 1,4-dibromo-2,3-butanedione with water, methanol and sodium sulfite

Sulfonates are well-known substances with a variety of applications, e.g. as surfactants. On the other hand, bis(sulfonates) bearing hydroxyl or keto group(s) in between the sulfonate groups can be used with or without further modification as starting materials for the preparation of new type of molecules capable to form either complexes or in general supramolecular structures. The synthesis of three hydroxyl-bearing bis(sulfonates), 2-hydroxypropane-1,3-bis(sodium sulfonate) 4, DL-2,3-dihydroxybutane-1,4-bis(sodium sulfonate) 8, and sodium 2,3,4-trihydroxy-1-sulfonate 7 (as by-product) via the Strecker sulfonation are described. Interestingly, under similar conditions, sulfonation of 1,4-dibromo-2,3-butanedione 9 was found to be very complicated and no pure product could be isolated, despite previously reported results on sulfonation of α-halogenated ketones in high yields. There are indications that SO3 2 - attacks at the carbonyl carbon of 9 followed by rearrangement and expulsion of SO4 2 - . 1,4-dibromo-2,3-butanedione 9, bearing two keto groups next to methylene groups, can potentially exist as enols or in the case of its solution in hydroxylic solvents in the form of hemiketals or geminal diols. This behavior of 9 when is dissolved in CDCl3, CD3OD and D2O was studied by means of UV-Vis, 1H and 13C NMR and the nature of the adducts formed was elucidated.

Poly(Alkylene 2,5-Thiophenedicarboxylate) Polyesters: A New Class of Bio-Based High-Performance Polymers for Sustainable Packaging

In the present study, 100% bio-based polyesters of 2,5-thiophenedicarboxylic acid were synthesized via two-stage melt polycondensation using glycols containing 3 to 6 methylene groups. The so-prepared samples were characterised from the molecular point of view and processed into free-standing thin films. Afterward, both the purified powders and the films were subjected to structural and thermal characterisation. In the case of thin films, mechanical response and barrier properties to O2 and CO2 were also evaluated. From the results obtained, it emerged that the length of glycolic sub-units is an effective tool to modulate the chain mobility and, in turn, the kind and amount of ordered phases developed in the samples. In addition to the usual amorphous and 3D crystalline phases, in all the samples investigated it was possible to evidence a further phase characterised by a lower degree of order (mesophase) than the crystalline one, whose amount is strictly related to the glycol sub-unit length. The relative fraction of all these phases is responsible for the different mechanical and barrier performances. Last, but not least, a comparison between thiophene-based homopolymers and their furan-based homologues was carried out.

Diethyl [(2,5-diiodo-4-methylphenyl)methyl]phosphonate

The title compound, C12H17I2O3P, was prepared in three steps from p-xylene. Heterodimers between nearly identical molecules are connected via three hydrogen bonds from benzylic and ester methylene groups to phosphonate. The dimers form chains along the a-axis direction, stabilized by C—H...O bridges.

A Photoredox-Catalyzed Approach for Formal Hydride Abstraction to Enable Csp3–H Functionalization with Nucleophilic Partners

While a great number of C–H functionalization methods have been developed in recent years, new mechanistic paradigms to deconstruct such bonds have been comparatively rare. Amongst possible strategies for breaking a C<i>_sp³</i>–H bond are deprotonation, oxidative addition with a metal catalyst, direct insertion via a nitrene intermediate, hydrogen atom transfer (HAT) with both organic and metal-based abstractors, and lastly, hydride abstraction. The latter is a relatively unexplored approach due to the unfavorable thermodynamics of such an event, and thus has not been developed as a general way to target both activated and unactivated C<i>_sp³</i>–H bonds on hydrocarbon substrates. Herein, we report our successful efforts in establishing a catalytic C–H functionalization manifold for accessing an intermediate carbocation by formally abstracting hydride from unactivated C<i>_sp³</i>–H bonds. The novel catalytic design relies on a stepwise strategy driven by visible light photoredox catalysis and is demonstrated in the context of a C–H fluorination employing nucleophilic fluorine sources. Difluorination of methylene groups is also demonstrated, and represents the first C–H difluorination with nucleophilic fluoride. Additionally, the formal hydride abstraction is shown to be amenable to several other classes of nucleophiles, allowing for the construction of C–C or C–heteroatom bonds.

Crystallization of Long-Spaced Precision Polyacetals III: Polymorphism and Crystallization Kinetics of Even Polyacetals Spaced by 6 to 26 Methylenes

In this paper we extend the study of polymorphism and crystallization kinetics of aliphatic polyacetals to include shorter (PA-6) and longer (PA-26) methylene lengths in a series of even long-spaced systems. On a deep quenching to 0 °C, the longest even polyacetals, PA-18 and PA-26, develop mesomorphic-like disordered structures which, on heating, transform progressively to hexagonal, Form I, and Form II crystallites. Shorter polyacetals, such as PA-6 and PA-12 cannot bypass the formation of Form I. In these systems a mixture of this form and disordered structures develops even under fast deep quenching. A prediction from melting points that Form II will not develop in polyacetals with eight or fewer methylene groups between consecutive acetals was further corroborated with data for PA-6. The temperature coefficient of the overall crystallization rate of the two highest temperature polymorphs, Form I and Form II, was analyzed from the differential scanning calorimetry (DSC) peak crystallization times. The crystallization rate of Form II shows a deep inversion at temperatures approaching the polymorphic transition region from above. The new data on PA-26 confirm that at the minimum rate the heat of fusion is so low that crystallization becomes basically extinguished. The rate inversion and dramatic drop in the heat of fusion irrespective of crystallization time are associated with a competition in nucleation between Forms I and II. The latter is due to large differences in nucleation barriers between these two phases. As PA-6 does not develop Form II, the rate data of this polyacetal display a continuous temperature gradient. The data of the extended polyacetal series demonstrate the important role of methylene sequence length on polymorphism and crystallization kinetics.

Ruthenium(III) Based Diimine Complexes; Synthesis, Characterization, PXRD Study and Catalytic Hydrogenation of Cyclohexene

This study deals with preparation and characterization of a group of RuIII-chelates contains tetradentate diimine ligands. These quadridentate ligands are derived from 2-OH-1-naphthaldehyde and a number of aliphatic diamines where the number of methylene groups between the two azomethine nitrogen donors varied from two to six are the components of quadridentate ligands. The pure isolated compounds were subjected to several physicochemical investigations to assign their structures. Spectral and magnetic measurements suggested a distorted octahedral arrangement of the six coordinate diimine ruthenium(III) complexes. The structural optimization for one of the current RuIII-complexes was determined based on the processing of powder X-ray diffraction (PXRD) data by the computer program Expo 2014 PXRD. As well DFT calculations were applied to optimize the geometry in the case of complexes 1. The newly synthesized ruthenium(III) diimines were tested as catalysts for hydrogenation of cyclohexene. The effect of the catalyst structure and the type of catalysis as well as the nature and amount of the solvent used on the catalytic performance of the current catalysts were studied. Catalytic experiments reported that the ongoing ruthenium(III) complexes are promising precatalysts that have successfully catalyzed hydrogenation of cyclohexene by hydrogen gas under moderate process conditions. The results obtained allowed to establish a mechanism for the studied catalytic hydrogenation reactions.