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The Effect of Alkyl Chain Length on Well-Defined Fluoro-Arylated Polythiophenes for Temperature-Dependent Morphological Transitions.

ABSTRACT: Understanding the relationship between the molecular structure and morphological behaviors of well-defined semiconducting polymers is essential for developing novel conjugated building blocks and determining the origin of the functional characteristics of semiconducting polymers. Here, we provide insights into the significant temperature-dependent morphological transitions of novel well-defined polythiophene derivatives with m-alkoxy-substituted fluoro-aryl side units: poly(3-(4-fluoro-3-(hexyloxy)phenyl)thiophene) (PHFPT) and poly(3-(4-fluoro-3-(dodecyloxy)phenyl)thiophene) (PDFPT). We found that these unique morphological transitions depend on the alkyl chain length of the substituted fluoro-aryl side units. In PHFPT with short alkyl chains, the thermal treatment promotes a crowded interdigitated packing structure, resulting in narrow lamellar spacings in its crystalline structure. In contrast, the long alkyl chain of PDFPT acts as a physical spacer and disturbs the crowded interdigitation. In addition, the thermal treatment induces the backbone planarization and an ordered packing morphology in PDFPT. These demonstrations provide a critical milestone for the phase transitions of semiconducting polymers with conjugated side units.

SUBMITTER: Ochiai Y

PROVIDER: S-EPMC7774253 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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The Effect of Alkyl Chain Length on Well-Defined Fluoro-Arylated Polythiophenes for Temperature-Dependent Morphological Transitions.

Ochiai Yuto Y Higashihara Tomoya T

ACS omega 20201217 51

Understanding the relationship between the molecular structure and morphological behaviors of well-defined semiconducting polymers is essential for developing novel conjugated building blocks and determining the origin of the functional characteristics of semiconducting polymers. Here, we provide insights into the significant temperature-dependent morphological transitions of novel well-defined polythiophene derivatives with <i>m</i>-alkoxy-substituted fluoro-aryl side units: poly(3-(4-fluoro-3- ...[more]

PMID: 33403308

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Project description:New cobalt(III) bis(dicarbollide) complexes covalently linked to two 2-oligothienyl units have been synthesized and electropolymerized in acetonitrile electrolyte in order to produce the corresponding polythiophene films containing in-chain metallic centers. The polymer films electrogenerated from the bithienyl (4b) and terthienyl (4c) derivatives display redox processes attributed to the Co(III)/Co(II) couple at ca. -1.1 V vs SCE and to the p-doping/undoping of the expected quaterthienyl and sexithienyl segments at ca. 0.8 V vs SCE. In contrast, the anodic oxidation of the thienyl (4a) derivative leads to passivation of the electrode surface. As the length of the oligothiophene substituents increases, the metallic and dicarbollide cage carbon atoms contributions in the HOMO decrease dramatically so that the highest occupied frontier orbitals of 4b and 4c can be considered as almost purely oligothiophene-based. From further UV-vis spectroscopy analysis, it is demonstrated that the polymer incorporating the sexithienyl segments is more conjugated than that with the quaterthienyl segments as the absorption maximum for the interband pi-pi* transition was observed at 410 and 448 nm for poly(4b) and poly(4c) respectively. Furthermore, these polymers display a more extended degree of conjugation than the parent oligothiophenes. Such features indicate a significant electronic delocalization through the cobaltabisdicarbollide moiety. Their conducting probe atomic force microscopy characterization indicates that poly(4b) and poly(4c) behave like heavily doped semiconductors rather than pure semiconductors. Mean conductivity values extracted from the current-voltage profiles are 1.4 x 10(-4) and 7.5 x 10(-4) S cm(-1) for poly(4b) and poly(4c), respectively. Such materials are found to be efficient for the electrocatalytic reduction of protons to dihydrogen, as exemplified for poly(4b). The overpotential for hydrogen evolution is significantly decreased by ca. 230 mV with respect to that obtained with the bare electrode (measured for a current density of 1.4 mA cm(-2) in the presence of 20 mM HBF(4)).

Project description:Solvents that stabilize protein structures can improve and expand their biochemical applications, particularly with the growing interest in biocatalytic-based processes. Aiming to select novel solvents for protein stabilization, we explored the effect of alkylammonium nitrate protic ionic liquids (PILs)-water mixtures with increasing cation alkyl chain length on lysozyme conformational stability. Four PILs were studied, that is, ethylammonium nitrate (EAN), butylammonium nitrate (BAN), hexylammonium nitrate (HAN), and octylammonium nitrate (OAN). The surface tension, viscosity, and density of PIL-water mixtures at low to high concentrations were firstly determined, which showed that an increasing cation alkyl chain length caused a decrease in the surface tension and density as well as an increase in viscosity for all PIL solutions. Small-angle X-ray scattering (SAXS) was used to investigate the liquid nanostructure of the PIL solutions, as well as the overall size, conformational flexibility and changes to lysozyme structure. The concentrated PILs with longer alkyl chain lengths, i.e., over 10 mol% butyl-, 5 mol% hexyl- and 1 mol% octylammonium cations, possessed liquid nanostructures. This detrimentally interfered with solvent subtraction, and the more structured PIL solutions prevented quantitative SAXS analysis of lysozyme structure. The radius of gyration (Rg) of lysozyme in the less structured aqueous PIL solutions showed little change with up to 10 mol% of PIL. Kratky plots, SREFLEX models, and FTIR data showed that the protein conformation was maintained at a low PIL concentration of 1 mol% and lower when compared with the buffer solution. However, 50 mol% EAN and 5 mol% HAN significantly increased the Rg of lysozyme, indicating unfolding and aggregation of lysozyme. The hydrophobic interaction and liquid nanostructure resulting from the increased cation alkyl chain length in HAN likely becomes critical. The impact of HAN and OAN, particularly at high concentrations, on lysozyme structure was further revealed by FTIR. This work highlights the negative effect of a long alkyl chain length and high concentration of PILs on lysozyme structural stability.

Project description:BackgroundBiocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification.Methodology/principal findingsMagnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe(3)O(4) were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining.Conclusions/significanceThe activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization enabling efficient enzyme recovery and recycling.

Dataset Information

The Effect of Alkyl Chain Length on Well-Defined Fluoro-Arylated Polythiophenes for Temperature-Dependent Morphological Transitions.

Publications

The Effect of Alkyl Chain Length on Well-Defined Fluoro-Arylated Polythiophenes for Temperature-Dependent Morphological Transitions.

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