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[cn]daisy chain molecular muscle architectures are self‐assemblies of hermaphrodite monomers, which usually contain a macrocycle unit linked to a molecular thread that contains sites of interactions – i. e. molecular stations – for the macrocycle. In these multiply threaded structures, altering with control the affinity between macrocycles and stations allows for contraction and extension of the molecule, which is reminiscent of the operation of a muscle. Besides, the field that consists of combining helix and template‐containing rods to design foldaxane supramolecular assemblies is still underexplored. By using foldamer units as surrogates for macrocycles, Gan et al. reported the first supramolecular muscle‐like foldamer‐containing switch that can adopt, after chemical stimulus, either a contracted co‐conformational state or a degenerate‐like state for which a slow exchange occurred between the contracted and the stretched state. [ABSTRACT FROM AUTHOR]

A sustainable upgrading of renewable bulk materials, obtained by decomposition of biomass lignocellulose, could facilitate their use in the industrial production of chemicals. Homogeneous ruthenium catalysis plays a fundamental role in this area. The review deals with the upgradation of lignocellulosic molecules through the formation of new C−C and C−N bonds. Selected examples of catalytic bond forming reactions reported until mid of 2023, include: (a) dehydrogenative based couplings of alcohols, (b) reductive amination of carbonyl compounds, (c) direct C−H functionalization of (hetero)aromatic compounds. These approaches fulfill the requirements of sustainability: application occurs without any previous substrate activation, thus reducing the production of waste. New chemicals containing the intrinsic molecular structure of lignocellulose substrates, showed a broad range of applications: green fuels, hydrogen carriers, monomers of polymers, intermediates of fine chemicals and pharmaceuticals. The results discussed in the review could inspire the reader to improve the valorization process, in terms of bio‐substrate scope as well as product complexity, through more strategic applications of the catalytic methods. [ABSTRACT FROM AUTHOR]

• Summarized the initial ozonolysis rules of typical LCMs in the atmosphere. • Predicted eco-toxicity of CEB-2F and its transformation products. • Revealed the adsorption mechanism of typical LCMs on the surface of TiO 2 clusters. • Elucidated the role of TiO 2 clusters on the ozonolysis of typical LCMs. • Illustrated the long-distance transmission capability of LCMs. Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers (LCMs). In this work, we investigated the reaction mechanisms and kinetics of three typical LCMs (4-cyano-3,5-difluorophenyl 4-ethylbenzoate (CEB-2F), 4-cyano-3-fluorophenyl 4-ethylbenzoate (CEB-F), and 4-cyanophenyl 4-ethylbenzoate (CEB)) with ozone (O 3) in the atmospheric gas, liquid, and particle phases employing density functional theory (DFT). Here, O 3 is prone to add to the benzene ring without F atom(s) in the selected LCMs. The ozonolysis products are aldehydes, carboxylic acids, epoxides, and unsaturated hydrocarbons containing aromatic rings. Those products undergo secondary ozonolysis to generate small molecular compounds such as glyoxal, which is beneficial for generating secondary organic aerosol (SOA). Titanium dioxide (TiO 2), an essential component of mineral aerosol particles, has good adsorption properties for LCMs; however, it slightly reduces the reactivity with O 3. At 298 K, the reaction rate constant of the selected LCMs reacting with O 3 in the gas and atmospheric liquid phases is (2.74‒5.53) × 10−24 cm3/(mol·sec) and 5.58 × 10−3‒39.1 L/(mol·sec), while CEB-2F reacting with O 3 on (TiO 2) 6 cluster is 1.84 × 10−24 cm3/(mol·sec). The existence of TiO 2 clusters increases the persistence and long-distance transportability of LCMs, which enlarges the contaminated area of LCMs. [Display omitted] [ABSTRACT FROM AUTHOR]

The incorporation of BN units in organic scaffolds by isoelectronic/isosteric substitution of selected CC couples has emerged as an efficient tool to produce new materials with useful properties and functions. The knowledge about BN‐doped inorganic–organic hybrid polymers, however, is still rather scarce. This is especially true for linear or cyclolinear macromolecules that feature longer inorganic chains. Herein, we introduce 1,2,5‐azadiborolane as a polymer building block for the first time. An attempt to apply it for the synthesis of a cyclolinear poly(iminoborane) resulted after only two B−N coupling events in the formation of a molecular compound comprising a chain of three nitrogen and two boron atoms – as confirmed by single‐crystal X‐ray diffractometry. In combination with a p‐phenylene diamine‐based co‐monomer, we accomplished to incorporate the 1,2,5‐azadiborolane into a hybrid polymer of considerable molecular weight that features a B2N3 chain. We additionally synthesized a small molecular model compound for the polymer and characterized it crystallographically as well. Comparison of the UV‐vis spectra of the monomer, the oligomer, and the polymer revealed systematic red‐shifts of the longest‐wavelength absorption band with increasing number of BN units in the chain. [ABSTRACT FROM AUTHOR]

The creation of complementary products via templating is a hallmark feature of nucleic acid replication. Outside of nucleic acid‐like molecules, the templated synthesis of a hetero‐complementary copy is still rare. Herein we describe one cycle of templated synthesis that creates homomeric macrocyclic peptides guided by linear instructing strands. This strategy utilizes hydrazone formation to pre‐organize peptide oligomeric monomers along the template on a solid support resin, and microwave‐assisted peptide synthesis to couple monomers and cyclize the strands. With a flexible templating strand, we can alter the size of the complementary macrocycle products by increasing the length and number of the binding peptide oligomers, showing the potential to precisely tune the size of macrocyclic products. For the smaller macrocyclic peptides, the products can be released via hydrolysis and characterized by ESI‐MS. [ABSTRACT FROM AUTHOR]

The Arg-specific gingipains of Porphyromonas gingivalis RgpA and RgpB have 97% identical sequences in their catalytic domains yet their propeptides are only 76% identical. RgpA isolates as a proteinase–adhesin complex (HRgpA) which hinders direct kinetic comparison of RgpAcat as a monomer with monomeric RgpB. We tested modifications of rgpA identifying a variant that enabled us to isolate histidine-tagged monomeric RgpA (rRgpAH). Kinetic comparisons between rRgpAH and RgpB used benzoyl-l-Arg-4-nitroanilide with and without cysteine and glycylglycine acceptor molecules. With no glycylglycine, values of Km, Vmax, kcat and kcat/Km for each enzyme were similar, but with glycylglycine Km decreased, Vmax increased and kcat increased ~ twofold for RgpB but ~ sixfold for rRgpAH. The kcat/Km for rRgpAH was unchanged whereas that of RgpB more than halved. Recombinant RgpA propeptide inhibited rRgpAH and RgpB with Ki 13 nM and 15 nM Ki respectively slightly more effectively than RgpB propeptide which inhibited rRgpAH and RgpB with Ki 22 nM and 29 nM respectively (p < 0.0001); a result that may be attributable to the divergent propeptide sequences. Overall, the data for rRgpAH reflected observations previously made by others using HRgpA, indicating rRgpAH fidelity and confirming the first production and isolation of functional affinity tagged RgpA. [ABSTRACT FROM AUTHOR]

Hydrogels incorporating different reactive groups are important platforms for the fabrication of functional materials through the conjugation of diverse molecules. In this study, a dual-reactive hydrogel system was designed utilizing aldehyde and azide groups containing methacrylate monomers. Hydrogels were obtained in the presence of a dimethacrylate crosslinker with a combination of hydrophilic PEG-based monomers via free-radical polymerization. The azide and aldehyde sites of the hydrogel network are reactive towards alkyne and amine functional groups, respectively. The advantage of the different reactivities of these functional groups was demonstrated through the attachment of two different dye molecules onto the hydrogel platform via the "Huisgen click" and "Schiff base" reactions to obtain a sensing platform for various applications, such as indicating change in pH of the environment. [ABSTRACT FROM AUTHOR]

The jumbo phages encode proteins that assemble to form a nucleus-like compartment in infected cells. Here we report the cryo-EM structure and biochemistry characterization of gp105, a protein that is encoded by the jumbo phage 201φ2-1 and is involved in the formation of the nucleus-like compartment in phage 201φ2-1 infected Pseudomonas chlororaphis. We found that, although most gp105 molecules are in the monomeric state in solution, a small portion of gp105 assemble to form large sheet-like assemblies and small cube-like particles. Reconstruction of the cube-like particles showed that the particle consists of six flat head-to-tail tetramers arranged into an octahedral cube. The four molecules at the contact interface of two head-to-tail tetramers are 2-fold symmetry-related and constitute a concave tetramer. Further reconstructions without applying symmetry showed that molecules in the particles around the distal ends of a 3-fold axis are highly dynamic and have the tendency to open up the assembly. Local classifications and refinements of the concave tetramers in the cube-like particle resulted in a map of the concave tetramer at a resolution of 4.09 Å. Structural analysis of the concave tetramer indicates that the N and C terminal fragments of gp105 are important for mediating the intermolecular interactions, which was further confirmed by mutagenesis studies. Biochemistry assays showed that, in solution, the cube-like particles of gp105 are liable to either disassemble to form the monomers or recruit more molecules to form the high molecular weight lattice-like assembly. We also found that monomeric gp105s can self-assemble to form large sheet-like assemblies in vitro, and the assembly of gp105 in vitro is a reversible dynamic process and temperature-dependent. Taken together, our results revealed the dynamic assembly of gp105, which helps to understand the development and function of the nucleus-like compartment assembled by phage-encoded proteins. [ABSTRACT FROM AUTHOR]

In this work, the effects of adsorbed water on the structural evolution in the PVDF layer of composite hydrophobic MFFC-3 and hydrophilic MFFC-3G membranes were studied using ATR IR spectroscopy. It has been found that adsorbed water molecules initiate the conformational rearrangement of PVDF polymer molecules in the hydrophilic membrane layer, while the conformation of PVDF polymer molecules in the hydrophobic membrane layer does not change. The deconvolution of the absorption bands of the stretching vibrations of OH groups was carried out using four Gaussians. Based on the frequencies of the Gaussian peaks, the energy was calculated and the hydrogen bonds of adsorbed water were classified. It is shown that the structure of adsorbed water with hydrogen bond energies EOH = 42.8, 35.7, 17.9, and 14 kJ/mol are "clusters" with three or four hydrogen bonds. Energy values EOH = 17.9, 10.6, 16.8, and 14 kJ/mol correspond to OH bonds of dimeric and monomeric water molecules. It is concluded that the structure of adsorbed water in the PVDF layer can be characterized by a mixed model of hydrogen bonds, consisting of monomeric, dimeric molecules, and associated clusters with hydrogen bond energies from 10.6 to 42.8 kJ/mol. A comparative analysis of the ATR IR spectra of water-saturated samples indicates that the adsorbed water molecules in the PVDF "polymer–water" interfacial space of the hydrophobic membrane do not form a layer of bound water, while, in the hydrophilic membrane, water enters the structure of molecules, forming a layer of bound water. [ABSTRACT FROM AUTHOR]

In this article, we used the numerical self-consistent field method of Scheutjens–Fleer to study the micellization of hybrid molecules consisting of one polylysine dendron with charged end groups and several linear hydrophobic tails attached to its root. The main attention was paid to spherical micelles and the determination of the range of parameters at which they can appear. A relationship has been established between the size and internal structure of the resulting spherical micelles and the length and number of hydrophobic tails, as well as the number of dendron generations. It is shown that the splitting of the same number of hydrophobic monomers from one long tail into several short tails leads to a decrease in the aggregation number and, accordingly, the number of terminal charges in micelles. At the same time, it was shown that the surface area per dendron does not depend on the number of hydrophobic monomers or tails in the hybrid molecule. The relationship between the structure of hybrid molecules and the electrostatic properties of the resulting micelles has also been studied. It is found that the charge distribution in the corona depends on the number of dendron generations G in the hybrid molecule. For a small number of generations (up to G = 3 ), a standard double electric layer is observed. For a larger number of generations ( G = 4 ), the charges of dendrons in the corona are divided into two populations: in the first population, the charges are in the spherical layer near the boundary between the micelle core and shell, and in the second population, the charges are near the periphery of the spherical shell. As a result, a part of the counterions is localized in the wide region between them. These results are of potential interest for the use of spherical dendromicelles as nanocontainers for drug delivery. [ABSTRACT FROM AUTHOR]

Persistent radicals, which are generated from 2‐oxindole or benzofuranone dimers, are useful tools for designing the radical‐based cross‐coupling reaction to provide molecules containing a quaternary carbon. The persistent radical is accessible from both the dimer and monomer; however, the reactivity difference between these substrates for the oxidative cross‐coupling reaction is not fully understood, most likely because of the mechanistic complexity. Here, we present details of an aerobic cross‐dehydrogenative coupling (CDC) reaction using various monomers and catechols. UV‐Vis analysis and mechanistic control experiments showed that the monomer is less reactive than the dimer under aerobic conditions. Our Pd(II)‐BINAP‐μ‐hydroxo complex significantly improved the reactivity of the monomers for the aerobic CDC reaction with catechols, yielding results comparable to those of the corresponding dimer. The procedure, which enables the generation of the persistent radical in situ, is particularly useful when employing the monomer that is not readily converted to the corresponding dimer. [ABSTRACT FROM AUTHOR]

Measurement of velocity distributions of evaporated water monomers from small mass- and energy-selected protonated water clusters allows probing the extent of thermalization after excitation of these ultimately small nanodroplets. Electronic excitation of a molecule in the cluster is here induced by a single collision with an argon atom in the keV energy range. The measured velocity distributions of the departing neutral molecules exhibit bimodal shapes with a lower-velocity part consistent with a complete redistribution of the deposited energy in the entire cluster and a higher-velocity contribution corresponding to evaporation before complete energy redistribution. Statistical molecular dynamics calculations reproduce the bimodal shape of the velocity distributions by assuming an initial spreading of the excitation energy among all modes, thereby reproducing the lower velocity contribution of the distribution. By contrast, assuming the deposited energy to be initially localized among the modes of a single molecule leads to calculated distributions with two components whose shape is in accordance with the experimental results. The characteristics and the relative abundance of these two contributions in the velocity distributions obtained are presented and discussed as a function of the number of molecules (n = 2-10) in the ionized nanodroplet H+(H2O)n. [ABSTRACT FROM AUTHOR]

Among the enticing issues of chiral origins are: how chirality is born from the initial achiral units and the mechanisms for the transfer of chiral information. In this work, by combining a physical vortex and chiral seeds, a general process is revealed to generate chiral supramolecular polymers from achiral C3‐symmetric molecules. The symmetry‐broken assemblies from the achiral molecules could work as chiral seeds to initiate the polymerization of either homologous or heterologous achiral monomers. Concomitantly, the fragmentation of the polymer caused by the vortex during the nucleation‐elongation stages is shown to enlarge the domains of the chiral nuclei and then guide the polymer to grow into the predominant helicity with a high reactivity ratio. Moreover, the chiral structural information can be stored in different forms of assemblies. These new polymerization modes will provide guidance for the preparation of chiral materials. [ABSTRACT FROM AUTHOR]

Step‐growth polymerized systems of general type "AfiBgi" are considered. The monomers bear one or more reactive groups of type A and/or B. An A group on one monomeric unit might react with a B group on another unit, thus coupling the two units. This process repeats itself randomly, and at a given degree of conversion, a wide range of polymeric molecules has formed, differing in both molecular size and in branching structure, determined by the laws of probability. In a slice of the molecular size distribution, all polymeric molecules have the same size, but differ in number and position of branching points. A method is presented to calculate the path length distribution for each such slice. Here, path length is the number of chemical bonds in the path connecting two monomeric units in the molecule. From the path length distribution, the light scattering function is calculated. [ABSTRACT FROM AUTHOR]

In this paper, odd-even effects in liquid crystals are briefly summarised. Based on the position and type of the repeating units, odd-even effects can be caused by methylene (CH2)k units either when terminating the LC molecules or separating monomers in dimers or polymers, or by the parity of the number of rigid mesogenic units separated by odd numbered methylene spacers. These odd-even effects are manifested themselves in the transition temperatures (mainly of the clearing point) and transition entropies, but they can also lead to alteration of phases, such as antiferroelectric or ferroelectric, or the appearance of tilted or orthogonal mesophases. These alternating phase and entropy properties then also lead to alternating secondary properties, such as in birefringence and elastic properties. In each category, we also discuss the theoretical considerations that can explain the observed odd-even effects. [ABSTRACT FROM AUTHOR]

Here, we report a medium‐to‐polymer anomalous chiral transfer in the supramolecular polymerization of a tetraphenylporphyrin‐based achiral hydrogen‐bonding monomer (TPP) in a chiral medium of 5‐cyanobiphenyl CB*. A mixture of TPP in (R)‐CB* ([TPP]=7.7 mol %) at 40 °C gave a columnar oblique LC mesophase, where the individual columns were composed of an optically active helical supramolecular polymer of TPP as a consequence of a successful medium‐to‐polymer chiral transfer. Meanwhile, upon dilution of CB* with achiral 5‐cyanobiphenyl CB, the optical activity of the system showed an anomalous bell‐shaped dependency on the composition of CB*/CB, where the gabs value of 0.049 at CB*/CB=50/50 was 6.0 times larger than the gabs value of CB* alone. Such anomalous chiroptical amplification in CD is most likely due to a change in the stacking geometry of TPP in the oblique columnar LC upon lateral compression. [ABSTRACT FROM AUTHOR]

Supramolecular self-assembly by hybrid macrocycles containing both cucurbit[m]uril (CB[m]) and pillar[n]arene was discussed and summarized in this review. Due to different solubility, diverse-sized cavities, and various driving forces in recognizing guests, the role of CB[m] and pillar[n]arene in such hybrid macrocyclic systems could switch between competitor in capturing specialized guests, and cooperator for building advanced hybridized macrocycles, by controlling their characteristics in host–guest inclusions. Furthermore, both CB[m] and pillar[n]arene were employed for fabricating advanced supramolecular self-assemblies such as mechanically interlocked molecules and supramolecular polymers. In those self-assemblies, CB[m] and pillar[n]arene played significant roles in, e.g., microreactor for catalyzing particular reactions to bridge different small pieces together, molecular "joint" to connect different monomers into larger assemblies, and "stabilizer" in accommodating the guest molecules to adopt a favorite structure geometry ready for assembling. [ABSTRACT FROM AUTHOR]

[Display omitted] Sulfavant A and Sulfavant R, sulfoquinovoside-glycerol lipids under study as vaccine adjuvants, structurally differ only for the configuration of glyceridic carbon, R/S and R respectively. The in vitro activity of these substances follows a bell-shaped dose–response curve, but Sulfavant A gave the best response around 20 µM, while Sulfavant R at 10 nM. Characterization of aqueous self-assembly of these molecules by a multi-technique approach clarified the divergent and controversial biological outcome. Supramolecular structures were present at concentrations much lower than critical aggregation concentration for both products. The kind and size of these aggregates varied as a function of the concentration differently for Sulfavant A and Sulfavant R. At nanomolar range, Sulfavant A formed cohesive vesicles, while Sulfavant R arranged in spherical micellar particles whose reduced stability was probably responsible for an increase of monomer concentration in accordance with immunomodulatory profile. Instead, at micromolar concentrations transition from micellar to vesicular state of Sulfavant R occurred and thermodynamic stability of the aggregates, assessed by surface tensiometry, correlated with the bioactivity of Sulfavant A at 20 µM and the complete loss of efficacy of Sulfavant R. The study of Sulfavants provides clear evidence of how self-aggregation, often neglected, and the equilibria between monomers and aqueous supramolecular forms of lipophilic molecules deeply determine the overall bio-response. [ABSTRACT FROM AUTHOR]

The quasi-variational quantum chemical protocol and code GENIUSH [E. Mátyus et al., J. Chem. Phys. 130, 134112 (2009) and C. Fábri et al., J. Chem. Phys. 134, 074105 (2011)] has been augmented with the complex absorbing potential (CAP) technique, yielding a method for the determination of rovibrational resonance states. Due to the effective implementation of the CAP technique within GENIUSH, the GENIUSH-CAP code is a powerful tool for the study of important dynamical features of arbitrary-sized molecular systems with arbitrary composition above their first dissociation limit. The GENIUSH-CAP code has been tested and validated on theH2He+ cation: the computed resonance energies and lifetimes are compared to those obtained with a previously developed triatomic rovibrational resonance-computing code, D²FOPI-CCS [T. Szidarovszky and A. G. Császár Mol. Phys. 111, 2131 (2013)], utilizing the complex coordinate scaling method. A unique feature of the GENIUSHCAP protocol is that it allows the simple implementation of reduced-dimensional dynamical models. To prove this, resonance energies and lifetimes of the H2⋅CO van derWaals complex have been computed utilizing a four-dimensional model (freezing the two monomer stretches), and a related potential energy surface, of the complex. [ABSTRACT FROM AUTHOR]

In this paper, we present new ideas for computing rovibrational energy levels of molecules composed of two components and apply them to H2O-Cl-. When both components are themselves molecules, Euler angles that specify their orientation with respect to an axis system attached to the inter-monomer vector are used as vibrational coordinates. For H2O-Cl-, there is only one set of Euler angles. Using Euler angles as intermolecular vibrational coordinates is advantageous because in many cases coupling between them and coordinates that describe the shape of the monomers is unimportant. The monomers are not assumed to be rigid. In the most efficient calculation, vibrational wavefunctions of the monomers are used as contracted basis functions. Energy levels are calculated using the Lanczos algorithm. [ABSTRACT FROM AUTHOR]

[Display omitted] • We derived size distribution function for AB g + AB h + B f type hyperbranched polymerization. • We derived degree of branching for the AB g + AB h + B f type hyperbranched polymerization. • The work help understand and design structure and molecular parameters of AB g type HPs. The unified analytical expressions of the size distribution function and the degree of branching for the hyperbranched polymerization with AB g type monomers are developed by kinetic theory of polymerization, based on the AB g + AB h + B f model. The effect of the reactant parameters, the monomers branching degree g and h , the monomers feed ratio r , the functionality f and feed ratio α of the core molecule B f , on the molecular parameters of the products formed was investigated. Compared with the general polycondensation of AB g monomer or copolycondensation of AB g and AB monomer without core molecule, the presence of multifunctional core molecules makes the polydispersity index of the products go down fast when the reaction approaches completion. At the end of the reaction, the polydispersity index increases with increasing g , and decreases with increasing α and f. For the AB g + AB + B 3 polycondensation system, within the range of the feed ratio of AB g monomer less than 0.3, the average chain segment length significantly decreases with the increasing r , and then the change becomes moderate with its further increase. For g > 2, the average chain segment length shows a shallow minimum with increasing r. The degree of branching, fractions of terminal and branching units also show maximum value with the change of monomer feed ratio r. The information obtained in this work can help people understand the structure of AB g type hyperbranched polymers and carry out molecular design. [ABSTRACT FROM AUTHOR]

• UV irradiation completely removed fluorinated liquid crystal monomers CEB-F. • O 2 •− and 3CEB-F⁎ are critical for the photolysis of CEB-F. • Possible degradation products and pathways were proposed. • CEB-F was highly toxic to D. magna , and the toxicity of CEB-F solution is significantly reduced after UV irradiation. Despite the frequent detection of fluorinated liquid-crystal monomers (FLCMs) in the environment, the level of understanding of their fate, toxicity, and transformation remains insufficient. Herein, we investigated the degradation kinetics and mechanism of an FLCM (4-cyano-3-fluorophenyl 4-ethylbenzoate, CEB-F) under ultraviolet (UV) photolysis in aquatic environment. Our findings demonstrated that the UV photolysis of CEB-F followed first-order kinetics. Photodegradation products were identified using liquid chromatography with mass spectrometry, and detailed reaction pathways were proposed. It is postulated that through the attack of reactive oxygen species, hydroxylation, and C O/C-F bond cleavage, CEB-F gradually degraded into small molecular compounds, releasing fluorine ions. Acute immobilization tests with Daphnia magna (D. magna) revealed significant acute toxicity of CEB-F, with LC 50 values ranging from 1.023 to 0.0536 μM over 24 to 96 h, emphasizing the potential high risk of FLCMs in aquatic ecosystems if inadvertently discharged. Interestingly, we found that the toxicity of CEB-F photolysis reaction solutions was effectively reduced. Through catalase and acetylcholinesterase activities analysis along with molecular docking simulation, we proposed differences in the underlying toxicity mechanisms of CEB-F and its photolysis products to D. magna. These findings highlight the potential harmful effects of FLCMs on aquatic ecosystems and enrich our understanding of the photolysis behavior of FLCMs. [Display omitted] [ABSTRACT FROM AUTHOR]

The compatibility of 17 elastomers with two dioxolane molecules was assessed by volume change and hardness measurements. Each molecule was blended with diesel in concentrations of 0, 10, 20 and 30 wt.%. The elastomers included two fluorocarbons, six acrylonitrile butadiene rubbers (NBRs), and one each of fluorosilicone, chloroprene rubber (CR), polyurethane, styrene butadiene rubber (SBR), hydrogenated NBR (HNBR), a blend of NBR and PVC (OZO), epichlorohydrin/ ethylene oxide (ECO), ethylene propylene diene monomer (EPDM), and silicone. Specimens of each elastomer were immersed in the test fuels for a period of 4 weeks and measured for property change. Afterwards they were dried at 60°C for 20 h and remeasured. The results showed that the dioxolanes were suitable with many of the elastomers and that the performances were essentially the same for both molecules. The dioxolanes were found to either have negligible impact beyond neat diesel or they produced a small increase in swell. This minimal impact is attributed to the fact that the solubility parameters (especially those associated with polarity and hydrogen bonding) of the dioxolanes are similar to those of diesel. As a result, little change in solubility and hence swell occurred when dioxolane was added to the diesel. [ABSTRACT FROM AUTHOR]

A rhodium(II)‐catalyzed asymmetric cyclooligomerization of bifunctional monomers possessing triazolyl and vinyl groups at 2,3‐ and 3,4‐positions on the thiophene ring is studied. Structurally interesting cyclic dimers in which thienylene and cyclopropylene units are alternately connected are obtained as the major components. The eight‐membered rings in the center are non‐planar and adopt a tub‐shaped conformation. We also observe the phenomenon of racemization caused by a tub‐to‐tub ring‐flipping, the activation energy of which is determined as 108 kJ mol−1 by electronic circular dichroism spectra measurement. [ABSTRACT FROM AUTHOR]

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The logic of DNA molecules is explained as a consequence of their main functions: efficiently duplicating polymers conveying enormous quantities of biological information with minimal spatial occupancy. An abstract model is provided, where monomers are represented by triangles, that was materialized by means of a 3D printer. [ABSTRACT FROM AUTHOR]

Purpose: To assess the resin microtensile bond strength (MTBS) and the degree of conversion (DC) of indirect composite resin restorations polymerized with light and heat. Materials and Methods: Two direct (Filtek Z100 and Premise) and one indirect (Premise Indirect) composite resins were polymerized with a combination of light and heat (138°C for 20 min). For MTBS, 42 cylinders were fabricated (n = 7). After the surface treatment, cylinders were bonded to each other using adhesive resin (Optibond FL). Specimens were stored in water for 24 h. Another 15 cylinders (n = 5) were fabricated for determining degree of conversion using Fourier Transform Infrared Spectrometry immediately and at 24 h. The MTBS and the DC was submitted to two-way ANOVA. The interaction with existing data was explored with univariate ANOVA and two-way ANOVA. Tukey's HSD post-hoc test was used to detect pairwise differences (α = 0.05). Results: The MTBS to light and heat polymerized Z100 was 75.7 MPa, significantly higher than that to Premise (58.6 MPa) and Premise Indirect (63.9 MPa). The immediate DC for Z100, Premise, and Premise Indirect were 51.0%, 68.7%, and 61.8%, respectively. The DC at 24 h ranged from 53.4% (Z100) to 72.8% (Premise Indirect) and significantly increased for Premise Indirect only. Comparison with previously published data revealed that the heat treatment increased both MTBS and DC of Premise and Premise Indirect. Conclusion: Z100 showed better bond strength but lower DC. Heat treatment and a 24-h delay before delivery can benefit DC of Premise Indirect. The increase in DC of Premise and Premise Indirect did not affect their bond strength. Keywords: adhesion, bond strength, direct composite resin, dental materials, indirect composite resin, degree of conversion. [ABSTRACT FROM AUTHOR]

Dihydromethanopterin reductase (DmrB), is a naturally occurring cage protein found in various archaeal and a few bacterial species. It exists as 24mer with cubic geometry where 8 trimeric subunits are present at the corners of each cube. Each trimer is made up of three monomeric units and six FMN, where two molecules of FMN are present at the interface of each monomer. DmrB is involved in the conversion of dihydromethanopterin to tetrahydromethanopterin using FMN as a redox equivalent. In the present study, we have used spectroscopic and biochemical techniques along with complementary bio-informatic work to understand the assembly principles of the DmrB. Our results show a concentration dependant self-assembly of DmrB which is mediated by ionic interactions. The co-factor FMN stabilizes and preserves the secondary and quaternary structure of DmrB against thermal insult, indicating that the higher order assembly of DmrB is very thermostable. Our work provides an interesting piece of information regarding the role of the co-factors in the thermostability of these classes of cage proteins. The understanding of the assembly and disassembly of this thermostable cage would enable the downstream usage of this system in various nano-biotechnological applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Step‐growth polymerizing systems of type "A1+A2+A3" are considered. The monomers bear one (A1), two (A2), or three (A3) identical reactive sites. In the reactor vessel, at a given degree of conversion, a wide range of polymeric molecules has formed, differing in both molecular size and in branching structure, determined by the laws of probability. In a slice of the molecular size distribution, all polymeric molecules have the same size (i.e., are built up by the same number of monomeric units), but differ in number and position of branching points (A3's). A method is presented to calculate the path length distribution for each such slice. Here, path length is the number of chemical bonds in the path connecting two monomeric units in the molecule. The shape and moments of this distribution may help rheologists and polymer manufacturers in improving the properties of their products. The system "A1+A2+A3" is the most simple representative of the more general step‐growth polymerizing systems of type "Afi," and of type "AfiBgi." Extension of this calculation method to these for the chemical industry more relevant systems is intended. [ABSTRACT FROM AUTHOR]

As resin-based composites (RBC) replace dental amalgam for environmental reasons, there is a requirement to understand the environmental impact of this alternative dental restorative material. In this study we standardize the simultaneous detection of five monomeric components associated with RBCs using high performance liquid chromatography (HPLC) coupled with solid-phase microextraction (SPME). Factors affecting method performance (detection wavelength, calibration conditions, method sensitivity/accuracy/precision, extraction time/efficiency) are evaluated using standard solutions containing the mixture of TEGDMA, UDMA, Bis-GMA, BPA and HEMA. Detection sensitivity and analytical efficiency of the method is optimized for these compounds using 200 nm detection wavelength, PDMS/DVB fiber and extraction time of 90 min. Analytical accuracy of the HPLC is >95% for all monomers, with precision of 2.3–5.1%. Detection limits under the conditions described are 25 µg/L for HEMA, BPA, UDMA, Bis-GMA, and 100 µg/L for TEGDMA. The extraction time is governed by the largest molecular weight compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Smart nanomaterials that transduce external stimuli. • Synthesis of a new platform of smart hybrid nanosystems (SHN) for positively charged probe loading. • Integrative characterization of structure and behavior, including a sound NMR-based methodology. • Drug release successfully controlled guided by the dual responsiveness of SNH. • Remote-controlled external of response that opens a gate for application as nanocarriers. Smart nanosystems consisting of inorganic particles and responsive polymers display significant and remarkable aspects. Such combined work exploits a facile path for multifunctional nanomaterials and facilitates various novel technological applications due to "live" polymer components. Here, we report the design and synthesis of a new platform of smart hybrid nanosystems (SHN) for positively charged probe loading and specific release under pH and temperature-controlled conditions. The SHN was prepared by a simple sequential method that produced an integrated core–shell nanomaterial with a dual stimulus response and excellent colloidal stability. Further, we demonstrate by crossing DLS and NMR results that these core–shell nanosystems present transduction from both stimuli to a mechanical shrinkage of the polymeric shell, leading to a remote-controlled dual response that can be synthetically tuned by controlling the molar ratio between monomers. Finally, we studied the potential of these SHN as molecular carriers and demonstrated that they are useful for selective ionic encapsulation of positively charged molecules, which release is controlled by the dual responsiveness. We successfully extended this concept to doxorubicin release triggered by T and pH changes, which opens possibilities of using these SHN improving results and patient compliance in chemotherapy treatments. [ABSTRACT FROM AUTHOR]

Polyrotaxanes, composed of multiple cyclic molecules threaded onto a polymer chain axis capped with bulky molecules, exhibit unique structural features wherein cyclic molecules can move along a chain. We have previously constructed biointerfaces that utilize the molecular mobility of polyrotaxanes for controlling cellular responses. To implement the features in a three‐dimensionally engineered cellular microenvironment, this study developed supramolecular hydrogels using polyrotaxane cross‐linkers capped with 4‐vinylbenzyl groups at the terminals of a polymer chain axis, where the 4‐vinylbenzyl groups in the polyrotaxane allow polymerization with other polyrotaxanes to form polyrotaxane networks. Polyrotaxane hydrogels are successfully prepared without any additional monomers via redox polymerization. The dynamic viscoelasticity and swellability of the hydrogels can be varied depending on the concentration of the polyrotaxanes. When fibroblasts are cultured on hydrogels, sufficient adhesion for cultivation is observed. Therefore, polyrotaxane hydrogels demonstrate suitable potential as new supramolecular biomaterials with dynamic structural features. [ABSTRACT FROM AUTHOR]

Reconfigurable micro–nanostructures have been largely used in the development of modern photocontrol technology. In this work, a dynamically adjustable hydrogel of supramolecule structures is realized by molecule self-assembly and cross-link in microscale. Calculations based on the molecule modeling systematically illuminate the assembly process and the mechanism of the dynamically adjustable micro–nanostructure. The transmittance changes of the hydrogel, which are measured in the visible-light range before and after electric heating, show outstanding light-control function. Thus, the one-step fabrication, bio-compatibility (no initiator, cross linker, or monomer residual), and agile photocontrol application demonstrate the potential of the adjustable physically bonded hydrogel in development of low-loss and integrated dynamical light-control devices. [ABSTRACT FROM AUTHOR]

Diadamantyl ether (DAE, C20H30O) represents a good model to study the interplay between London dispersion and hydrogen‐bond interactions. By using broadband rotational spectroscopy, an accurate experimental structure of the diadamantyl ether monomer is obtained and its aggregates with water and a variety of aliphatic alcohols of increasing size are analyzed. In the monomer, C−H⋅⋅⋅H−C London dispersion attractions between the two adamantyl subunits further stabilize its structure. Water and the alcohol partners bind to diadamantyl ether through hydrogen bonding and non‐covalent Owater/alcohol⋅⋅⋅H−CDAE and C−Halcohol⋅⋅⋅H−CDAE interactions. Electrostatic contributions drive the stabilization of all the complexes, whereas London dispersion interactions become more pronounced with increasing size of the alcohol. Complexes with dominant dispersion contributions are significantly higher in energy and were not observed in the experiment. The results presented herein shed light on the first steps of microsolvation and aggregation of molecular complexes with London dispersion energy donor (DED) groups and the kind of interactions that control them. [ABSTRACT FROM AUTHOR]

Calix[n]arenes (abbreviated as CX[n]) are the macro-molecules based on phenol groups with a hydrophobic cavity to encapsulate a gas or small molecules. They are used as molecular vehicles. For instance, these molecules are used in the activation of the solubility of monomers in the specific media and in pharmaceutical drug delivery. The limit of the development of gaseous pollutants will be a vital subject in the future. The polluting gases NO3, NO2, CO2, N2, etc., need cage molecules, such as CX[4], to be encapsulated. In this report, the red shift of the H-bonding interactions of the CX[4]-gas (by adding the gas inside or outside the cavity) is clearly explained by the vibrational analysis. The electronic spectra of the complexes of CX[4] with NO3, NO2, CO2, and N2) exhibit a blue-shift pick in comparison with the ones observed for the CX[4] molecule. The electrophilic and nucleophilic sites of the stable host-guest have been investigated. Additionally, the non-covalent interactions have been calculated based on the reduced density gradient RDG and QTAIM theory. [ABSTRACT FROM AUTHOR]

A temperature‐directed micellar morphological transformation was developed using CABC multi‐block copolymers with a hydrophobic block A, a hydrophilic block B, and a thermally responsive block C with a lower critical solution temperature (LCST). The micellar structure was switched from a star (below LCST) to a flower (above LCST). The transition temperature was tunable in a wide range (11–90 °C) by varying the C monomer composition. The large difference in the loading capacity between the star and flower enabled efficient encapsulation and controlled release of external molecules. Unlike conventional systems, the present star‐to‐flower transformation keeps micellar structures and hence does not liberate polymers but only external molecules selectively. Another application is a hidden functional segment. A functional segment is hidden (shielded) below the LCST and exposed to interact with external molecules or surfaces above the LCST. [ABSTRACT FROM AUTHOR]

The oxidation of vinyl compounds such as styrene, α‐methylstyrene, methyl methacrylate, acrylonitrile with molecular oxygen in the presence of N‐hydroxyphthalimide have been studied. It was shown that the N‐hydroxyphthalimide is efficient in initiation of the oxidative polymerization of vinyl monomers. The products of the monomer oxidation at 66 °C and 1 atm of O2 are corresponding polyperoxides and low molecular carbonyl compounds. IR‐ and 1H NMR spectroscopy confirm the alternating copolymer structure of polyperoxides with –O–O– bonds in the main chain. In the oxidative polymerization of vinyl monomers initiated with the mixtures of N‐hydroxyphthalimide and 2,2′‐azobisisobutyronitrile or benzoyl peroxide it was observed a synergistic effect of initiators' action. N‐hydroxyphthalimide reacts with molecular oxygen, initiator radicals or monomer to form the phthalimide‐N‐oxyl radical, which participates in the chain initiation stage and does not participate in the termination stages, which leads to a synergistic effect. [ABSTRACT FROM AUTHOR]

We report the first measurement of the spectrum of the NO–N2 complex in the region of the first vibrational NO overtone transition. The origin band of the complex is blueshifted by 0.30 cm-1 from the corresponding NO monomer frequency. The observed spectrum consists of three bands assigned to the origin band, the excitation of one quantum of z-axis rotation and one associated hot band. The spacing of the bands and the rotational structure indicate a T-shaped vibrationally averaged structure with the NO molecule forming the top of the T. These findings are confirmed by high level ab initio calculations of the potential energy surfaces in planar symmetry. The deepest minimum is found for a T-shaped geometry on the A″-surface. As a result the sum potential also has the global minimum for this structure. The different potential surfaces show several additional local minima at slightly higher energies indicating that the complex most likely will perform large amplitude motion even in its ground vibrational state. Nevertheless, as suggested by the measured spectra, the complex must, on average, spend a substantial amount of time near the T-shaped configuration. [ABSTRACT FROM AUTHOR]

Microscopic computer simulations of fluids of long polymers are greatly restricted by the limits of current computational power, and so course-grained descriptions, accurate on molecular length scales, are essential to extending the range of accessible systems. For some phenomena, particularly dynamical entanglement, descriptions that eliminate all internal degrees of freedom from the polymers are too drastic, as intermediate wavelength degrees of freedom are essential to the effect. Employing first-principles liquid-state theory, we have developed a course-grained model for the intermolecular structure of melts of long homopolymer chains that maps each chain of hard-sphere monomers onto a chain of connected soft colloids. All dependence on system parameters is analytically expressed so the results may be immediately applied to melts with different polymer and thermodynamic properties to calculate effective potentials between the soft colloids on the chains, which can then be used to perform molecular dynamics simulations. These simulations will be able to capture the large wavelength structure of the system at greatly reduced computational cost, while still retaining enough internal degrees of freedom explicitly to describe the phenomena that occur on length scales much larger than the monomeric units that comprise the chain, but shorter than the size of the molecule. [ABSTRACT FROM AUTHOR]

Through some simple derivations, it is shown that the nonexpanded dispersion interaction energy between two molecules can entirely be written in terms of the densities and the exchange-holes of the monomers. Thus the suspicion of Becke and Johnson [J. Chem. Phys. 122, 154104 (2005)] that the dispersion energy might be related to fluctuating dipoles produced by the electrons and their accompanying exchange-holes is confirmed. However, it will be shown that the current asymptotic result for the dispersion energy is different from the Becke–Johnson model. Some preliminary results for the polarizabilities and dispersion coefficients of a few atoms and small molecules demonstrate that the approach described in this work might be useful to estimate response properties and long-range correlation energies of molecular systems in general. [ABSTRACT FROM AUTHOR]

A new method of calculation of the second-order dispersion energy is proposed. It is based on the Longuet-Higgins formula [Faraday Discuss. Chem. Soc. 40, 7 (1965)], which describes the dispersion interaction in terms of frequency-dependent density susceptibilities of monomers. In this study, the density susceptibilities are obtained from the coupled cluster theory at the singles and doubles level. Density fitting is applied in order to reduce the computational effort for the evaluation of density susceptibilities. It is shown that density fitting improves the scaling of the computational resources with molecular size by one order of magnitude without affecting the accuracy of the resulting dispersion energy. Numerical results are presented for several van der Waals molecules to illustrate the performance of the new approach. [ABSTRACT FROM AUTHOR]

The vibrational relaxation rates of the OH bending mode of monomeric H2O molecules diluted in various liquid halogenated methane and ethane derivates have been determined by a picosecond infrared pump-probe study. Relaxation time constants between 4.8 and 40.5 ps have been obtained. The discussion of the general solvent dependence suggests that in all cases the solvent fundamental with the smallest energy mismatch is favorably populated by this intermolecular energy transfer process. [ABSTRACT FROM AUTHOR]

The authors have studied adsorption of acetylene on Cu(110) by means of low-temperature scanning tunneling microscopy. Adsorbed molecules preferentially aggregate at 40 K to yield dimer, trimer, and larger islands on the surface. Isolated species (monomer) adsorbs on the fourfold hollow site with ∼sp3 rehybridization as characterized by inelastic electron tunneling spectroscopy. Tunneling electron induces an acetylene molecule to migrate along the trough of Cu(110). The migration proceeds in two steps: the molecule first hops to the adjacent long-bridge site and then to the next fourfold site. The voltage and current dependencies of the hopping probability show that the migration is induced by inelastic electron tunneling that causes vibrational excitation of mainly C–H stretch mode. [ABSTRACT FROM AUTHOR]

All-atom molecular dynamics simulations are used to study a single chain of poly(methacrylic acid) in aqueous solutions at various degrees of charge density. Through a combination of analysis on the radial distribution functions of water and snapshots of the equilibrated structure, we observe that local arrangements of water molecules, surrounding the functional groups of COO- and COOH in the chain, behave differently and correlated well to the resulting chain conformation behavior. In general, due to strong attractive interactions between water and charged COO- via the formation of hydrogen bonds, water molecules tend to form shell-like layers around the COO- groups. Furthermore, water molecules often act as a bridging agent between two neighboring COO- groups. These bridged water molecules are observed to stabilize the rodlike chain conformation that the highly charged chain reveals, as they significantly limit torsional and bending degrees of the backbone monomers. In addition, they display different dynamic properties from the bulk water. Both the resulting oxygen and hydrogen spectra are greatly shifted due to the presence of strong H-bonded interactions. [ABSTRACT FROM AUTHOR]

An implementation of three-body symmetry-adapted perturbation theory (SAPT) of intermolecular interactions based on Kohn-Sham (KS) description of monomers with dispersion and induction nonadditive energies obtained from KS frequency-dependent density susceptibilities [SAPT(DFT)] is presented. Using the density-fitting approach, the nonadditive dispersion energy can be obtained with O(N5) scaling with respect to the system size, the best scaling among all available methods of evaluating this quantity. Numerical results are reported for the helium, argon, water, and benzene trimers. The nonadditive energy computed for these systems is in a good agreement with benchmarks. Some hybrid perturbational-supermolecular approaches are proposed that can provide—with only O(N5) scaling—nonadditive energies with accuracy comparable to more expensive supermolecular methods, such as the third-order Mo\ller-Plesset perturbation theory. Such approaches can be used for studying nonadditive effects in systems larger than it is currently possible with supermolecular methods at a level high enough to capture all essential components of the three-body interaction energy. [ABSTRACT FROM AUTHOR]

Long-chain organic molecules, 1-halododecane, RX (X=Cl,Br), adsorbed on Si(111)-7×7 were shown to form stable dimeric corrals; type I around corner holes and type II around corner adatoms S. Dobrin et al. [Surf. Sci. Lett. 600, L43 (2006)]. Here we examine the molecular dynamics of corral formation, in which mobile physisorbed adsorbates spontaneously convert to immobile. At high coverage the mechanism gives evidence of involving collisions between mobile vertical monomers, giving types I and II immobile horizontal dimers, vD+vD→h2 (I, II). At low coverage mobile vertical monomers collide with immobile horizontal ones to form largely type-II corrals, vD+h→h2 (II). Thermal reaction of corrals with X=Br brominates the surface by two distinct molecular pathways, thought to have more general applicability: “daughter-mediated” reaction of vertical vA with a low activation energy (here Ea∼5 kcal mol-1) and “parent-mediated” reaction of horizontal h or h2 with high activation energy (here Ea=29 kcal mol-1). [ABSTRACT FROM AUTHOR]

We have established experimental strategies on how to create a Menger sponge-like fractal body and how to control its fractal dimension. The essence was to utilize alkylketene dimer (AKD), which spontaneously forms super-water-repellent fractal surface. We prepared “fractal AKD particles” with fractal surface structure as templates of pores in fractal body. The fractal body was synthesized by filling the remained space between the packed template particles with a tetramethyl orthosilicate solution, solidifying it by the sol-gel process, and removing the template by calcinations. We have succeeded in systematically creating fractal bodies of silica with different cross-sectional fractal dimensions Dcs=1.87, 1.84, and 1.80 using “fractal template particles” compressed under the ratio=1.0, 2.0, and 3.0, respectively. We also discussed the possibilities of their fractal geometries in comparison with mathematical models. We concluded that the created fractal bodies were close to a Menger sponge and its modified one. Our experimental strategy allows us to design fractality of porous materials. [ABSTRACT FROM AUTHOR]

The excess Helmholtz free energy functional for associating hard sphere fluid is formulated by using a modified fundamental measure theory [Y. X. Yu and J. Z. Wu, J. Chem. Phys. 117, 10156 (2002)]. Within the framework of density functional theory, the thermodynamic properties including phase equilibria for both molecules and monomers, equilibrium plate-fluid interfacial tensions and isotherms of excess adsorption, average molecule density, average monomer density, and plate-fluid interfacial tension for four-site associating hard sphere fluids confined in slit pores are investigated. The phase equilibria inside the hard slit pores and attractive slit pores are determined according to the requirement that temperature, chemical potential, and grand potential in coexistence phases should be equal and the plate-fluid interfacial tensions at equilibrium states are predicted consequently. The influences of association energy, fluid-solid interaction, and pore width on phase equilibria and equilibrium plate-fluid interfacial tensions are discussed. [ABSTRACT FROM AUTHOR]

A new six-dimensional interaction potential for the water dimer has been obtained by fitting interaction energies computed at 2510 geometries using a variant of symmetry-adapted perturbation theory (SAPT) based on density functional theory (DFT) description of monomers, referred to as SAPT(DFT). The stationary points, second virial coefficient, vibration-rotation-tunneling spectrum, and structure of liquid water computed with the new potential are in very good agreement with experiment and advanced ab initio calculations, confirming the high level of accuracy provided by SAPT(DFT). [ABSTRACT FROM AUTHOR]