Oligomeric Molecules Research Articles

Dimerized small molecule donor enables efficient ternary organic solar cells

Ternary organic solar cells (OSCs) are the feasible and efficient strategy to achieve the high-performance OSCs. It is of great significance to develop a superior third component candidate for constructing efficient ternary OSCs. In this work, we intelligently designed and synthesized a dimerized small molecule donor by connecting two asymmetric small molecule donors with the vinyl group, which is named DSMD-βV. This innovative oligomeric molecule DSMD-βV not only exhibits the complementary absorption and the cascade energy level arrangement with PM6 and BTP-eC9, but also regulates the phase separation micromorphology based on PM6:BTP-eC9. Consequently, PM6:DSMD-βV:BTP-eC9 based ternary device exhibits the improved exciton dissociation, charge transport and decreased recombination, thus achieving a superior power conversion efficiency (PCE) of 18.26 %, surpassing PM6:BTP-eC9 based binary (17.63 %). This work indicates that the dimerized small molecule donor is able to become a promising third component candidate, which also opens up a unique idea for the construction of efficient ternary organic solar cells.

On the isomeric purity of endcap molecules in cholesteric liquid crystal oligomers for near-infrared thermochromic coatings

ABSTRACT Structurally coloured responsive materials provide an interesting avenue for the development of autonomous temperature regulating window films. One interesting class of such thermochromic materials is cholesteric liquid crystals. However, cholesteric liquid crystals have rarely been applied in coatings for smart window applications. In this work, we report the synthesis of endcapped cholesteric liquid crystal oligomers and its application as near-infrared thermochromic coatings for windows. Two isomerically pure monoacrylate endcapping molecules and its isomeric mixture are synthesised. The molecules are used to synthesise a variety of endcapped cholesteric liquid crystal oligomers to study the effect of the isomeric purity on the thermochromic properties of the coatings. It is found that while the oligomers are almost identical in composition and phase behaviour, only one isomer produces a clear transparent coating, highlighting the significance of minute isomeric differences. Remarkably, the thermochromic behaviour of the coatings for all oligomers is the same. The best performing oligomer is able to reversibly blueshift by 250 nanometres when heated from room temperature to 100°C, opening the way of cholesteric liquid crystals for use in temperature regulating window films.

Crosslinking ionic oligomers sol-gel synthesis of high-surface-area mesoporous magnesium carbonate and its general applicability

Mesoporous magnesium carbonate has been widely used in controlled release of drugs, adsorption or catalysis. In traditional methods, expensive alkoxide or MgO are usually employed as Mg-source to prepare mesoporous magnesium carbonate. Herein, based on the crosslinking property of ionic oligomers, a novel crosslinking ionic oligomer sol-gel method was proposed to prepare high-surface-area mesoporous magnesium carbonate using cheap MgCl2·6H2O and CO2 as material. (MgCO3)n crosslinking oligomer sols was produced based on the H-bond capping effects of ethanol and triethylamine. The evolution mechanism of crosslinking (MgCO3)n oligomer sols to gels was studied by using ATR-FTIR and NMR. The results indicated that with the slow volatilization of ethanol and triethylamine, a part of H-bond disappeared, which initiating the chain growth of (MgCO3)n oligomer molecules, and finally forming a crosslinking network. Combined with a CO2 critical point drying process, amorphous mesoporous magnesium carbonate nanoparticle with high surface area was obtained and characterized using ATR-FTIR, XRD, XPS, nitrogen adsorption/desorption analysis, SEM, TEM and EDS systematically. The specific surface area of magnesium carbonate reached 628 m2 g−1 when the n(TEA)/n(Mg2+) was 40:1. Moreover, the general applicability of this method was verified. Mesoporous sulfate and phosphate were synthesized, which indicating the crosslinking oligomer sol-gel chemistry provided a general strategy for the construction of mesoporous inorganic oxysalt materials. Our work has important guiding significance for the preparation of other mesoporous materials that using cheap inorganic salt as raw material.

Giant oligomeric porous cage-based molecules.

Most reported porous materials are either extended networks or monomeric discrete cavities; indeed, porous structures of intermediate size have scarcely been explored. Herein, we present the stepwise linkage of discrete porous metal-organic cages or polyhedra (MOPs) into oligomeric structures with a finite number of MOP units. The synthesis of these new oligomeric porous molecules entails the preparation of 1-connected (1-c) MOPs with only one available azide reactive site on their surface. The azide-terminated 1-c MOP is linked through copper(i)-catalysed azide-alkyne cycloaddition click chemistry with additional alkyne-terminated 1-c MOPs, 4-c clusters, or 24-c MOPs to yield three classes of giant oligomeric molecules: dimeric, tetrameric, or satellite-like, respectively. Importantly, all the giant molecules that we synthesised are soluble in water and permanently porous in the solid state.

Effects of altered backbone composition on the folding kinetics and mechanism of an ultrafast-folding protein.

Sequence-encoded protein folding is a ubiquitous biological process that has been successfully engineered in a range of oligomeric molecules with artificial backbone chemical connectivity. A remarkable aspect of protein folding is the contrast between the rapid rates at which most sequences in nature fold and the vast number of conformational states possible in an unfolded chain with hundreds of rotatable bonds. Research efforts spanning several decades have sought to elucidate the fundamental chemical principles that dictate the speed and mechanism of natural protein folding. In contrast, little is known about how protein mimetic entities transition between an unfolded and folded state. Here, we report effects of altered backbone connectivity on the folding kinetics and mechanism of the B domain of Staphylococcal protein A (BdpA), an ultrafast-folding sequence. A combination of experimental biophysical analysis and atomistic molecular dynamics simulations performed on the prototype protein and several heterogeneous-backbone variants reveal the interplay among backbone flexibility, folding rates, and structural details of the transition state ensemble. Collectively, these findings suggest a significant degree of plasticity in the mechanisms that can give rise to ultrafast folding in the BdpA sequence and provide atomic level insights into how protein mimetic chains adopt an ordered folded state.

Synthesis, properties, and pyrolysis of organoalumoxanes modified with refractory metals

Organoalumoxane oligomers modified with refractory metals (zirconium, hafnium or chromium) were synthesized. Their physico-chemical and fiber-forming properties were studied. Models of the group and elemental composition of oligomeric molecules of organoalumoxanes containing zirconium, hafnium or chromium were proposed. Based on the results of X-ray elemental microanalysis (SEM) and X-ray diffraction, it was found that pyrolysis of metal-containing organoalumoxanes at 1500°C in air results in the microcrystalline ceramic powders of corundum composition, modified with refractory metal oxides.

Evaluation of the effect of acid-base nature of inorganic filler on the performance properties of epoxypolymer composite materials

The paper considers the possibility of controlling the interfacial interactions of molecules of polar oligomers and the substrate by forming modified supramolecular structures as a result of acid-base interaction of components of the polymer matrix with the surface of nanodispersed oxides. The effect of aluminum oxide on the properties of ED-20 epoxy resin in the presence of the iso-ITA hardener has been studied: microstructure of oxide samples and acid-base properties of the oxide have been studied; the free energy of the surface and the work of adhesion of the material have been determined from the contact angle.

Novel Terahertz-Based Radiation Treatment of Alzheimer Disease

Alzheimer’s Disease Facts and Figures, an annual report released by the Alzheimer’s Association, reveals the burden of Alzheimer’s and dementia on individuals, caregivers, government and the nation’s health care system. Per the special report, More Than Normal Aging: Understanding Mild Cognitive Impairment (MCI), it is estimated 10% to 15% of individuals with MCI go on to develop dementia each year. Because of the narrow brain-blood barrier every medicine designed to treat Alzheimer’s failed due to inability of complex and large molecules to penetrate this barrier. <strong><span class="correspondence-author">Four steps of Alzheimer’s treatment by using proprietary Magtera Technology.</span></strong> <span class="correspondence-author"><strong>First step:</strong></span> Detect the THz modes for Aβ42 Oligomer. or any other micro bio structures proven to be responsible for Alzheimer’s. The most probable THz modes would be intermolecular modes: librations, low frequency bond vibrations; hydrogen bond stretches and distortions; molecular rotations. There are plenty of such modes. <span class="correspondence-author"><strong>Second step:</strong></span> detect the THz modes of healthy brain tissue. <span class="correspondence-author"><strong>Third step:</strong></span> Find a THz window of penetration in brain fluids that corresponds to one of these modes by using the highly tunable THz Magnon Laser that bridges the THz Gap and covers the whole THz spectrum. <span class="correspondence-author"><strong>Fourth step: </strong></span> Apply high power THz radiation by using the THz Magnon Laser at resonance frequencies that correspond to Aβ42 Oligomer molecular excitations but do nor coincide with THz modes of healthy brain tissue, and eradicate Aβ42 Oligomer molecules.

Synthesis, Structure, and Properties of Monodispersed and Highly Luminescent Organoborane Oligomers.

Organoborane oligomers with well-defined molecular structures and high luminescence are scarce, among which those with boron not used as bridging atoms are even more so. Here, a series of well-defined ethynyl-linked or butadiynyl-linked conjugated organoborane oligomers with high fluorescence quantum yield and extinction coefficient (i.e., high brightness) were prepared by coupling different building blocks featuring dithienooxadiborepine moieties. Single crystal structures of hexyl modified dithienooxadiborepine (1a-hex) and hexyl-modified butadiynyl-linked conjugated dimer (D2-hex) not only verified the identity of the molecular structures but also revealed that the introduction of the hexyl chains distorted the molecular structures due to steric hindrance. Optical measurements showed that the absorption and emission maxima of the six oligomeric molecules bathochromic shifted with increasing numbers of repeating units. Molecules without hexyl chains emit efficient fluorescence upon photoexcitation, and the fluorescence quantum efficiency of the ethynyl-linked conjugated dimer (D1) is close to unity. Theoretical calculation results using density functional theory methods are consistent with the single crystal data, allowing a better understanding of the spectral properties. Such results indicate that the method is efficient for expanding small organoborane molecules into π-conjugated oligomers, which can be used to modulate to emit different colors with high efficiency.

Kendrick mass defect analysis - a tool for high-resolution Orbitrap mass spectrometry of native lignin.

Lignin is the second most abundant biopolymer in nature and a promising renewable feedstock for the production of aromatic compounds, composite materials, sorbents, etc. Being a complex mixture of oligomeric molecules with anirregular structure, natural lignin is an extremely difficult object to study. Its molecular level characterization requires advanced analytical techniques among which atmospheric pressure photoionization Orbitrap mass spectrometry holds a promising place. In the present study, Kendrick mass defect (KMD) analysis was proposed to facilitate the visualization and interpretation of Orbitrap mass spectra of the biopolymer on an example of Siberian pine dioxane lignin preparation. The use of the typical guaiacylpropane structure C10H12O4 as a Kendrick base unit made it possible to effectively identify oligomer series with different polymerization degrees and structurally related compounds, as well as to reliably determine the elemental compositions and structures of oligomers with high molecular weights (> 1kDa). For the first time, KMD analysis was applied to the interpretation of the complex tandem mass spectra of lignin oligomers, rapid discrimination of the product ion series, and the establishment of the main collision-induced dissociation pathways. It was demonstrated that especially promising was the use of KMD filtering in the study of broadband fragmentation tandem mass spectra, which allows for the structural characterization of all oligomers with a particular degree of polymerization.

New insights into the chemical composition and formation mechanisms of secondary organic aerosols produced in the ozonolysis of limonene

Limonene is a wide-spread volatile organic compound in the atmosphere. Its fast reaction with ozone leads to a large range of low-volatility oxygenated products that can form aerosols through gas-to-particle conversion processes. However, the physical and chemical mechanisms at the origin of particle formation are still fairly unknown despite the general importance of atmospheric aerosols towards health and climate. In the present work, we combined experimental and theoretical approaches to potentially decipher new significant mechanisms in the ozonolysis of limonene. After a thorough analysis of secondary organic aerosol (SOA) chemical composition highlighting for the first time the formation of oligomers up to heptamer structures as well as linear organic diacids, we proposed a formation mechanism involving non-covalent hydrogen bonding implying carboxylic/carbonyl/hydroxy groups. Theoretical quantum chemical calculations on dimers and trimers confirmed the stability of such structures. Thus, the present results highlight the formation of large oligomeric molecules whose atmospheric fate and health impacts need to be investigated. More generally, it is suggested that these non-covalent H-bonds play a role in the first steps of SOA formation from terpene oxidation in the atmosphere.

Elucidating Biomass-Derived Pyrolytic Lignin Structures from Demethylation Reactions through Density Functional Theory Calculations

Pyrolytic lignin is a fraction of pyrolysis oil that contains a wide range of phenolic compounds that can be used as intermediates to produce fuels and chemicals. However, the characteristics of the raw lignin structure make it difficult to establish a pyrolysis mechanism and determine pyrolytic lignin structures. This study proposes dimer, trimer, and tetramer structures based on their relative thermodynamic stability for a hardwood lignin model in pyrolysis. Different configurations of oligomers were evaluated by varying the positions of the guaiacyl (G) and syringyl (S) units and the bonds βO4 and β5 in the hardwood model lignin through electronic structure calculations. The homolytic cleavage of βO4 bonds is assumed to occur and generate two free radical fragments. These can stabilize by taking hydrogen radicals that may be in solution during the intermediate liquid (pathway 1) formation before the thermal ejection. An alternative pathway (pathway 2) could occur when the radicals use intramolecular hydrogen, turning themselves into stable products. Subsequently, a demethylation reaction can take place, thus generating a methane molecule and new oligomeric lignin-derived molecules. The most probable resulting structures were studied. We used FTIR and NMR spectra of selected model compounds to evaluate our calculation approach. Thermophysical properties were calculated using group contribution methods. The results give insights into the lignin oligomer structures and how these molecules are formed. They also provide helpful information for the design of pyrolysis oil separation and upgrading equipment.

A solution structure analysis reveals a bent collagen triple helix in the complement activation recognition molecule mannan-binding lectin

Collagen triple helices are critical in the function of mannan-binding lectin (MBL), an oligomeric recognition molecule in complement activation. The MBL collagen regions form complexes with the serine proteases MASP-1 and MASP-2 in order to activate complement, and mutations lead to common immunodeficiencies. To evaluate their structure-function properties, we studied the solution structures of four MBL-like collagen peptides. The thermal stability of the MBL collagen region was much reduced by the presence of a GQG interruption in the typical (X-Y-Gly)n repeat compared to controls. Experimental solution structural data were collected using analytical ultracentrifugation and small angle X-ray and neutron scattering. As controls, we included two standard Pro-Hyp-Gly collagen peptides (POG)10-13, as well as three more peptides with diverse (X-Y-Gly)n sequences that represented other collagen features. These data were quantitatively compared with atomistic linear collagen models derived from crystal structures and 12,000 conformations obtained from molecular dynamics simulations. All four MBL peptides were bent to varying degrees up to 85o in the best-fit molecular dynamics models. The best-fit benchmark peptides (POG)n were more linear but exhibited a degree of conformational flexibility. The remaining three peptides showed mostly linear solution structures. In conclusion, the collagen helix is not strictly linear, the degree of flexibility in the triple helix depends on its sequence, and the triple helix with the GQG interruption showed a pronounced bend. The bend in MBL GQG peptides resembles the bend in the collagen of complement C1q and may be key for lectin pathway activation.

ИССЛЕДОВАНИЕ ПАРАМЕТРОВ АДСОРБЦИИ ЭТИЛГИДРОСИЛОКСАНА НА ПОВЕРХНОСТИ КАРБИДА ВОЛЬФРАМА

The article deals with the modification of the surface of tungsten carbide powder with ethylhydrosiloxane. The morphology and granulometric composition of the original tungsten carbide have been studied. To modify the powder, the oligomer is preliminarily dissolved in n-hexane. It is found that the adsorption equilibrium is established in the first hour. Based on the data obtained, an adsorption isotherm of oligomeric ethylhydrosiloxane molecules on tungsten carbide particles is plotted as a function of the equilibrium concentration. It has been established that the adsorption isotherm of oligomeric ethylhydrosiloxane molecules on tungsten carbide particles has a typical character of monomolecular (monolayer) adsorption. At an equilibrium concentration of 0.12 mg/cm3, the adsorption isotherm curve reaches a plateau. Data on the determination of the parameters of adsorption of oligomeric molecules of ethylhydrosiloxane on the surface of tungsten carbide are presented: the landing area occupied by one oligomer molecule and the thickness of the adsorption layer of the oligomer. It is shown that modification with ethylhydrosiloxane leads to a transition from a hydrophilic to a hydrophobic surface. To establish the hydrophobization of the surface of tungsten carbide after modification with ethylhydrosiloxane, authors determine the contact angles of surface wetting before and after modification. At oligomer concentrations above 0.12 mg/cm3, the contact angle of wetting the surface of tungsten carbide with water has a maximum value of 96±2°.

Molecular design, electronic structure and optoelectronic properties of vinyl fused monomeric and oligomeric benzothiazoles—A theoretical investigation

The organic semiconductors have apprehended a significant role in flexible, thin-film, electronics with different flavors of applications. They are fabricated into electronic devices to enhance their overall performance and efficiency. Optimizing the optoelectronic properties will improve the performance of the device. In this work, a theoretical investigation has been made on vinyl fused monomeric and oligomeric benzothiazole molecules were presented to propose new organic materials for organic electronics. Moreover, fourteen monomeric and oligomeric benzothiazole molecules designed with donors (-N(CH3)2, -OH) and acceptors (-CN, -CF3) to construct D-π-A frames. The DFT and TDDFT methods with B3LYP/6–31+G(d,p) and B3P86/6–311++G(d,p) basis set were employed to elucidate the optoelectronic properties of the designed molecules. Using these methods, several parameters such as the geometry, polarity (dipole, polarizability hyperpolarizability), FMO analysis, charge transport properties, molecular electrostatic potential (MEP), excited-state properties, and further molecular electronic structure properties of the designed molecules have been computed. The results obtained confirmed that the geometric parameters, HOMO-LUMO gap, ionization potential (IP), electron affinity (EA), reorganization energies (λ), polarizability, hyperpolarizability, and absorption and emission spectra of the designed candidates can be significantly tuned by substitution of different donor-acceptor groups and extending the benzothiazole ring and these compounds can be used to make efficient optoelectronics. The conclusion of the work reveals that -N(CH3)2:-CN and -CN:-OH substituted oligomers demonstrates significant optoelectronic properties which could be used in optoelectronic devices.

Autonomous Bionanorobots via a Cage-Shaped Silsesquioxane Vehicle for In Vivo Heavy Metal Detoxification.

Nanorobots hold great promise for integrated drug delivery systems that are responsive to molecular triggers. Herein, we successfully developed an automatic smart bionanorobot that has transport capability and recognizes and removes zinc ions from poisoned cells based on nanoscale polyhedral oligomeric silsesquioxane molecules. This intelligent bionanorobot can easily move inside and outside the cell and find zinc ions owing to its highly selective recognition to zinc ions and high cell permeability, especially the well-combined high penetration and strong binding energy. More importantly, it was also found that this intelligent bionanorobot can restore round HeLa cells to a normal fusiform cell morphology following high-concentration zinc treatment and does not interfere with cell proliferation and division. It was also shown by in vivo experiments that the bionanorobot can inhibit persistent enlargement of the liver caused by zinc ion poisoning.

Helical Foldamers and Stapled Peptides as New Modalities in Drug Discovery: Modulators of Protein-Protein Interactions

A “foldamer” is an artificial oligomeric molecule with a regular secondary or tertiary structure consisting of various building blocks. A “stapled peptide” is a peptide with stabilized secondary structures, in particular, helical structures by intramolecular covalent side-chain cross-linking. Helical foldamers and stapled peptides are potential drug candidates that can target protein-protein interactions because they enable multipoint molecular recognition, which is difficult to achieve with low-molecular-weight compounds. This mini-review describes a variety of peptide-based foldamers and stapled peptides with a view to their applications in drug discovery, including our recent progress.

The Role of Cations of the Precipitant in the Interaction of Protein Molecules in the Lysozyme Oligomers in Crystallization Solutions

At the moment, the main opinion is that protein crystallization depends mainly on the the precipitant anions, therefore, there have been only few works devoted to the problem of the influence of its cations. Using the molecular dynamics method, we investigated the stability, changes in the compactness and structural transformations of lysozyme dimers and octamers in solutions with different precipitants (LiCl, NaCl, KCl and CuCl2) in order to study the contribution of cations during crystal formation in more detail. As a result, we found that cations have a rather noticeable effect on the behavior of oligomers: the higher the atomic mass of the cation, the greater the changes in the dimers structures during its dynamics and, according to the data of SAXS experiments, the lower the concentration of dimers. However, for octamers, this dependence is more complicated.

Direct fabrication of a diffraction grating onto organic oligomer crystals by focused ion beam lithography followed by plasma etching

We demonstrated direct fabrication of a diffraction grating onto organic oligomer crystals by focused ion beam (FIB) lithography followed by argon/oxygen plasma etching. Surface analysis suggested that FIB irradiation broke the oligomer molecules near the crystal surface to form a carbonized layer resulting in emission quenching. The plasma etching removed the damaged layer near the crystal surface and successfully recovered the emission. This technique was applied to fabricate the diffraction grating onto organic oligomer crystals and provided diffracted peaks in their fluorescence spectra without significant emission quenching.

Short Pyridine-Furan Springs Exhibit Bistable Dynamics of Duffing Oscillators.

The intensive development of nanodevices acting as two-state systems has motivated the search for nanoscale molecular structures whose dynamics are similar to those of bistable mechanical systems, such as Euler arches and Duffing oscillators. Of particular interest are the molecular structures capable of spontaneous vibrations and stochastic resonance. Recently, oligomeric molecules that were a few nanometers in size and exhibited the bistable dynamics of an Euler arch were identified through molecular dynamics simulations of short fragments of thermo-responsive polymers subject to force loading. In this article, we present molecular dynamics simulations of short pyridine-furan springs a few nanometers in size and demonstrate the bistable dynamics of a Duffing oscillator with thermally-activated spontaneous vibrations and stochastic resonance.