Uniform Oligomers Research Articles

Density Function Theory Study on the Energy and Circular Dichroism Spectrum for Methylene-Linked Triazole Diads Depending on the Substitution Position and Conformation.

Since the discovery of metal-catalyzed azide-alkyne cycloadditions, 1,2,3-triazoles have been widely used as linkers for various residues. 1,2,3-Triazole is an aromatic five-membered cyclic compound consisting of three nitrogen and two carbon atoms with large dipoles that absorb UV light. In the past decade, we have been working on the synthesis of dense triazole polymers possessing many 1,2,3-triazole residues linked through a carbon atom in their backbone as a new type of functional polymer. Recently, we reported that stereoregular dense triazole uniform oligomers exhibit a circular dichroism signal based on the chiral arrangement of two neighboring 1,2,3-triazole residues. In this study, to investigate the chiral conformation of two neighboring 1,2,3-triazole residues in stereoregular dense triazole uniform oligomers, density functional theory (DFT) calculations were performed using 1,2,3-triazole diads with different substitution positions and conformations as model compounds and compared with our previous results.

Correction to “Synthesis of Stereoregular Uniform Oligomers Possessing a Dense 1,2,3-Triazole Backbone”

Correction to “Synthesis of Stereoregular Uniform Oligomers Possessing a Dense 1,2,3-Triazole Backbone”

Synthesis of Stereoregular Uniform Oligomers Possessing a Dense 1,2,3-Triazole Backbone

Recent remarkable progress of precision polymerization techniques has allowed researchers to synthesize polymers of controlled molecular weight, tacticity, and monomer sequence with narrow distributions. However, it is still a challenging subject to synthesize uniform polymers and oligomers, which possess specific molecular weight, tacticity, and monomer sequence. Utilizing the advantages of t-butyl 4-azido-5-hexynoate (tBuAH), which we designed recently, for the synthesis of uniform polymers and oligomers, uniform oligomers of different stereoregularities possessing a dense 1,2,3-triazole backbone were synthesized using optically active tBuAH precursors by iterative procedures containing azidation, deprotection of the protecting group, and copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC). The stereoregular uniform oligomers were characterized in the solid state by powder X-ray diffraction (PXRD) and in the solution state by pulse-field-gradient spin-echo (PGSE) NMR, ultraviolet (UV) absorption, and circular dichroism (CD) spectroscopic techniques. While the solubility of stereoregular uniform oligomers was investigated using common organic solvents, gelation was observed for solutions of two octamers of different stereoregularities in some solvents, e.g., toluene, tetrahydrofuran (THF), acetone, and methanol. It is noteworthy that the intermolecular attractive interaction depended on the stereoregularity in aprotic polar solvents, i.e., THF and acetone, presumably because of the different polarities of octamers.

Synthesis and Encapsulation of Uniform Star-Shaped Block-Macromolecules.

Linear uniform oligomers synthesized via a two-step iterative cycle are postmodified with uniform octaethylene glycol monomethyl ether and finally coupled via azide-alkyne cycloaddition to yield uniform star-shaped block macromolecules with a mass ranging from 10 to 14kDa. Each of the molecules is carefully characterized by NMR, electrospray ionization mass spectrometry (ESI-MS), and size exclusion chromatography (SEC) to underline their purity as well as their uniformity. The obtained star-shaped macromolecules are investigated in their ability to encapsulate dye molecules by carrying out qualitative solid-liquid phase transfer experiments.

Improvement in the electrochemical stability of Li[Ni0.5Co0.2Mn0.3]O2 as a lithium-ion battery cathode electrode with the surface coating of branched oligomer

Although layered Li[Ni0.5Co0.2Mn0.3]O2 (LNCM 523) is one of the most promising cathode materials for lithium-ion batteries, large capacity losses during charging and discharging, due to poor surface stability, have limited its application. Surface modifications can be effective at improving the electrochemical performance of cathode materials. In this study, an oligomer polymer, named LIVING, was synthesized from bisphenol A diglycidyl ether diacrylate and barbituric acid and then used it as a coating material for LNCM 523 particles. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and electrochemical methods were employed to investigate the structure, surface properties, thermal stabilities, and electrochemical properties of the electrodes. Both coated (LIVING@LNCM 523) and uncoated (LNCM 523) electrodes were tested for their battery performance. A cathode material coated with 0.5 wt.% of LIVING (0.5% LIVING@LNCM 523) at a layer thickness of approximately 10 nm showed enhanced cycle stability, with over 80.7% of the capacity retained after 100 cycles at a rate of 0.2C; in comparison, the LNCM 523 electrode retained no more than 66.2% of its capacity under the same conditions. The coated electrode (0.5% LIVING@LNCM 523) also exhibited a better rate capability, retaining about 91% of its initial capacity after applying various current loads, whereas LNCM 523 retained only 79% after applying the same current loads under the same conditions. The improved electrochemical performance of the modified electrode is attributed to the chemical interactions between LNCM 523 and LIVING providing a uniform and stable oligomer layer on the LNCM 523 surface, thereby preventing the LNCM 523 surface from deeper electrolyte ion intercalation and suppressing the growth of interfacial resistance. The coating material (LIVING) appears to have great potential for improving the electrochemical performance of layered structure cathode materials, with promising applications in highly energy demanding lithium-ion batteries.

Fair Look at Coordination Oligomerization of Higher α-Olefins.

Coordination catalysis is a highly efficient alternative to more traditional acid catalysis in the oligomerization of α-olefins. The distinct advantage of transition metal-based catalysts is the structural homogeneity of the oligomers. Given the great diversity of the catalysts and option of varying the reaction conditions, a wide spectrum of processes can be implemented. In recent years, both methylenealkanes (vinylidene dimers of α-olefins) and structurally uniform oligomers with the desired degrees of polymerization have become available for later use in the synthesis of amphiphilic organic compounds and polymers, high-quality oils or lubricants, and other prospective materials. In the present review, we discussed the selective dimerization and oligomerization of α-olefins, catalyzed by metallocene and post-metallocene complexes, and explored the prospects for the further applications of the coordination α-olefin dimers and oligomers.

Efficient Protocol for the Synthesis of "N-Coded" Oligo- and Poly(N-Substituted Urethanes).

Sequence-defined poly(N-substituted urethanes) were synthesized via a solid-phase iterative protocol including two successive orthogonal coupling steps: the formation of an activated carbonate and its chemoselective reaction with the secondary amine group of amino alcohol building blocks. This simple method was used to write binary information on the formed polymers using four-coded molecules, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(propylamino)ethanol, and 2-(butylamino)ethanol, symbolizing binary dyads 00, 01, 10, and 11, respectively. The method is fast and allows synthesis of uniform oligomers and polymers with controlled lengths (4-mer to 28-mer) and digital information sequences. Furthermore, the coded poly(N-substituted urethanes) were easily characterized by electrospray mass spectrometry and decoded by tandem mass spectrometry. Overall, these digital macromolecules offer interesting advantages over conventional sequence-coded polyurethanes, i.e., synthesis of longer chains, reduced synthesis times, and better solubility and processing in common organic solvents.

Rigid Oligomer from Lignin in Designing of Tough, Self-Healing Elastomers.

Converting lignin into well-defined compounds is often challenged by structural complexation and inorganic contamination induced by the pulping process. In this report, instead of breaking down lignin into small molecules, we extracted a uniform and rigid oligomer from the lignin waste stream. The multifunctional polyphenol oligomer containing carboxylic acid, alcohol, and phenol groups is highly reactive and brings stiffness into the material matrix. Tough and self-healing elastomers are economically prepared from this oligomer by a reaction with epoxy-terminated polyethylene glycol, without needing any solvent. Specifically, the polyaromatic backbone's rigidity enhances the elastomer's toughness, and the multiple polar substituents form a network of hydrogen bonding that heals the elastomer. Many other applications, including adhesives, hydrogels, coating, and metal scavengers, are envisioned based on this oligomer's unique properties.

Photocontrolled Synthesis of Abiotic Sequence-Defined Oligo(Phosphodiester)s.

A photoregulated phosphoramidite iterative process is studied for the synthesis of non-natural, digitally encoded oligo(phosphodiester)s. The oligomers are prepared using two reactive phosphoramidite monomers containing a 2-(2-nitrophenyl)propoxycarbonyl (NPPOC) protected OH group. The stepwise synthesis is performed on an OH-functional soluble polystyrene support, which allows recycling by precipitation in a nonsolvent. Repeating cycles involving phosphoramidite coupling, oxidation of phosphite to phosphate, and NPPOC deprotection by light irradiation at λ = 365 nm are performed in order to prepare oligomers with different lengths and sequences. Synthesis is conducted on a micromolar scale and good recycling yields are obtained in all cases. The use of a soluble polymer support allows an in-depth characterization of the NPPOC photo-deprotection step by 1 H NMR, UV spectroscopy, and size exclusion chromatography, and thus identification of optimal synthesis conditions. After cleavage from the support, the oligo(phosphodiester)s are characterized by tandem mass spectrometry, which confirms preparation of uniform sequence-coded oligomers.

Structurally uniform 1-hexene, 1-octene, and 1-decene oligomers: Zirconocene/MAO-catalyzed preparation, characterization, and prospects of their use as low-viscosity low-temperature oil base stocks

An original approach to α-olefin oligomerization as well as novel thermally stable zirconocene catalysts for use in such reactions has been elaborated. The method reported allows the achievement of fractions of lightweight α-olefin oligomers up to 90% yields without considerable formation of byproducts like internal alkenes, alkanes, and higher oligomers. Trimers, tetramers, and pentamers of 1-hexene, 1-octene, and 1-decene were isolated as individual compounds and were hydrogenated. Viscosity characteristics of the isolated saturated and unsaturated hydrocarbons have been studied at various temperatures. The isolated saturated oligomers of 1-octene and 1-decene outperform the traditional electrophilic oligomerization products in terms of viscosity indexes, pour points, and low-temperature viscosity.

Residue Y70 of the Nitrilase Cyanide Dihydratase from Bacillus pumilus Is Critical for Formation and Activity of the Spiral Oligomer.

Nitrilases pose attractive alternatives to the chemical hydrolysis of nitrile compounds. The activity of bacterial nitrilases towards substrate is intimately tied to the formation of large spiral-shaped oligomers. In the nitrilase CynD (cyanide dihydratase) from Bacillus pumilus, mutations in a predicted oligomeric surface region altered its oligomerization and reduced its activity. One mutant, CynD Y70C, retained uniform oligomer formation however it was inactive, unlike all other inactive mutants throughout that region all of which significantly perturbed oligomer formation. It was hypothesized that Y70 is playing an additional role necessary for CynD activity beyond influencing oligomerization. Here, we performed saturation mutagenesis at residue 70 and demonstrated that only tyrosine or phenylalanine is permissible for CynD activity. Furthermore, we show that other residues at this position are not only inactive, but have altered or disrupted oligomer conformations. These results suggest that Y70's essential role in activity is independent of its role in the formation of the spiral oligomer.

Coding in 2D: Using Intentional Dispersity to Enhance the Information Capacity of Sequence-Coded Polymer Barcodes.

A 2D approach was studied for the design of polymer-based molecular barcodes. Uniform oligo(alkoxyamine amide)s, containing a monomer-coded binary message, were synthesized by orthogonal solid-phase chemistry. Sets of oligomers with different chain-lengths were prepared. The physical mixture of these uniform oligomers leads to an intentional dispersity (1st dimension fingerprint), which is measured by electrospray mass spectrometry. Furthermore, the monomer sequence of each component of the mass distribution can be analyzed by tandem mass spectrometry (2nd dimension sequencing). By summing the sequence information of all components, a binary message can be read. A 4-bytes extended ASCII-coded message was written on a set of six uniform oligomers. Alternatively, a 3-bytes sequence was written on a set of five oligomers. In both cases, the coded binary information was recovered.

Coding in 2D: Using Intentional Dispersity to Enhance the Information Capacity of Sequence‐Coded Polymer Barcodes

AbstractA 2D approach was studied for the design of polymer‐based molecular barcodes. Uniform oligo(alkoxyamine amide)s, containing a monomer‐coded binary message, were synthesized by orthogonal solid‐phase chemistry. Sets of oligomers with different chain‐lengths were prepared. The physical mixture of these uniform oligomers leads to an intentional dispersity (1st dimension fingerprint), which is measured by electrospray mass spectrometry. Furthermore, the monomer sequence of each component of the mass distribution can be analyzed by tandem mass spectrometry (2nd dimension sequencing). By summing the sequence information of all components, a binary message can be read. A 4‐bytes extended ASCII‐coded message was written on a set of six uniform oligomers. Alternatively, a 3‐bytes sequence was written on a set of five oligomers. In both cases, the coded binary information was recovered.

Selective carboxylate induced thermal degradation of bacterial poly(3-hydroxybutyrate-co-4-hydroxybutyrate) – Source of linear uniform 3HB4HB oligomers

Study on bacterial poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB4HB)) thermal degradation employing mild reaction conditions and carboxylate salt is described. The chemical structure of the obtained oligomers was determined with the aid of 1H NMR and ESI-mass spectrometry techniques. The comparison of a non-volatile degradation products obtained via carboxylate-induced thermal degradation of the P(3HB4HB) with products of the model polymer pyrolysis revealed significant differences in structure of the resulting oligomers. Exclusive formation of linear oligomers terminated with unsaturated, on one end, and carboxyl, on the other end, groups was noticed in case of base-catalyzed degradation contrary to oligomers produced via pyrolysis which contained also macrocyclic structures and γ-butyrolactone. Moreover, the elaborated method demonstrates the ability to produce well-defined oligomers with controlled molar mass. The resulting oligomers have huge potential as macroinitiators or macromonomers and can be useful for further synthesis of more sophisticated polymeric materials.

Facile synthesis of polymer/Au heteronanoparticles

Oligomeric particles with thiol groups perpendicular to their surface were successfully fabricated in toluene. Uniform oligomer-gold nanocomposites were formed via coupling with gold nanoparticles through anisotropic Au-S interactions. Monodispersed nanoparticles consisting of one Au nanoparticle and one oligomer particle were created after dissociation in THF. Because of the simplicity of the synthetic process, our method should allow for the production of large quantities of these asymmetric nanocolloids.

Evaluation of a condensation nucleation light scattering detector for the analysis of synthetic polymer by supercritical fluid chromatography

A condensation nucleation light scattering detector (CNLSD) was adapted for use as a detector for supercritical fluid chromatography. The performance of the CNLSD was evaluated and compared to evaporative light-scattering detector (ELSD) using a well-defined equimass mixture of uniform poly(ethylene glycol) oligomers and a certified reference material of poly(ethylene glycol) 1000. The CNLSD was able to detect a 10 times less concentrated solution of uniform oligomers compared to the ELSD. The quantitativeness of CNLSD was high enough to obtain the molecular mass distribution of poly(ethylene glycol) 1000 without any calibrations; on the other hand, the original data measured by ELSD was about 4% smaller than the certified value of poly(ethylene glycol) 1000. The CNLSD was suitable for supercritical fluid chromatography as a mass concentration detector.

Cytoplasmic and Nuclear Accumulation of Antisense Oligomers Incubated as Streptavidin Delivery Nanoparticles

The cytoplasmic accumulation and nuclear targeting of antisense oligomers were evaluated in cell culture following incubation with the cell penetrating peptide tat or polyargenine as a two-component delivery nanoparticle using streptavidin as linker. The fluorescent labeled uniform phosphodiester (PO), phosphorothioate (PS) and MORF oligomers were antisense to the mdr1 mRNA and were studied in KB-G2 (Pgp++) and KB-31 (Pgp+/-) cells. Fluorescence microscopy showed much higher cellular accumulation using the antisense compared to the sense PS/tat nanoparticle. The distribution in cells receiving either the PS or MORF, but not the PO, antisense oligomers in all of their forms showed definite migration to the nucleus. Incubations in KB-G2 cells of all three antisense oligomers with streptavidin as the onecomponent or including tat as the two-component nanoparticles led to increases in Rhodamine 123 accumulation by 200∼250% compared to free oligomers, almost certainly due to antisense interference with Pgp function. Thus presence of the streptavidin linker had no obvious detrimental influence on the functions of the carriers or the antisense oligomers. Since nuclear migration appears to be a characteristic property of oligomers, delivery via the nanoparticle may be a useful method of increasing the accumulation into the nucleus of antisense oligomers radiolabeled for Auger emittingbased radiotherapy.

Quantitative comparison of a corona-charged aerosol detector and an evaporative light-scattering detector for the analysis of a synthetic polymer by supercritical fluid chromatography

A corona-charged aerosol detector (CAD) was developed to improve the sensitivity, reproducibility and quantitativeness of detection as compared to evaporative light-scattering detector (ELSD) for liquid chromatography. Our laboratory used the corona CAD as a detector for supercritical fluid chromatography (SFC) and evaluated its performance compared to the ELSD by using a certified reference material of poly(ethylene glycol) (PEG) and a well-defined equimass mixture of uniform PEG oligomers. The corona CAD was able to detect a 10 times more dilute solution of uniform oligomers compared to the ELSD. Although the original data of molecular mass by ELSD was 4.6% smaller than the certified value of PEG 1000, molecular mass distribution obtained by corona CAD was virtually almost the same as the certified value without any calibrations.

Calibration of an evaporative light-scattering detector as a mass detector for supercritical fluid chromatography by using uniform Poly(ethylene glycol) oligomers

The quantitativeness of an evaporative light-scattering detector (ELSD) for supercritical fluid chromatography (SFC) was evaluated by using an equimass mixture of uniform poly(ethylene glycol) (PEG) oligomers. Uniform oligomers, in which all molecules have an identical molecular mass, are useful for the accurate calibration of detectors. We calibrated the SFC-ELSD system for various concentrations and molecular masses by using an equimass mixture of PEG oligomers. ELSD not only showed a good linear response to the injected concentration over a wide concentration range, from 10 −4 to 10 −1 g/mL, but also showed a strong dependence on the molecular mass of the solute. By using chromatograms of the equimass mixture of uniform oligomers to calibrate SFC-ELSD, it was possible to determine exact values of not only the average mass but also the molecular-mass distribution for a PEG 1540 sample. The average molecular mass was shifted to a higher value by several percentage points after calibration of the ELSD.

Synthesis of Uniform, Non-Natural Oligomers

Oligomers with well-defined chain lengths are of interest as foldamers, are important as model compounds for high-molecular-weight polymers and find application in electrooptic and sensory devices. This account presents an overview of the strategies that are available for the synthesis of eight important classes of uniform oligomers. The continuous refinement of the synthetic methods ­allows the preparation of ever longer oligomers in higher yields and also makes it possible to introduce special functional groups. These improvements could lead to materials with new or improved properties and underline the importance of synthetic organic chemistry for the development of new functional materials.