The preparation of 1,4-dicarbonyl, 4-oxo nitrile,furan, and pyrrole monomers

Treatment of cyclopentadiene-blocked acrolein with α,β-unsaturated ketones, esters, and nitriles in the presence of a thiazoliurn salt under basic conditions led to a simple method for the preparation of acetonylmethyl Vinyl ketone, 2-carboxymethylethyl vinyl ketone, and 2-cyanoethyl vinyl ketone. In addition, the cyclopentadiene-blocked acetonylmethyl vinyl Ketone was converted to heterocyclic furan and pyrrole monomers.     

Copolymerization of fluorinated monomers with nonfluorinated monomers. Reactivity and mechanisms

The copolymerization of two monomers usually leads to random copolymers except when one of both bears an electron-acceptor group and the other one has an electron-donor group. Many copolymers are commercially available, mainly in the series of hydrogenated monomers (S.M.A., GANTREZ, MALIALIM resins). The field of fluorinated copolymers is very interesting because of the strong electron-acceptor behaviour of the fluorine atoms and more generally of halogenated atoms. Thus, after HALAR (CTFE^a)-ethylene), TEFZEL (TFE-ethylene) and AFLAS (TFE^b)-propylene) resins, a new series of resins have been produced (copolymers of CTFE and vinyl ethers commercialized by ASAHI Corp.). So it can be considered that ACCEPTOR-DONOR copolymerization with fluorinated monomers is one of the most important applications of that kind of research. After reminding the main mechanisms of that reaction (homopolymerization of charge transfer complex and copolymerization of free monomers), it will be discussed about the mechanism in some examples (CTFE-vinyl ethers and other pairs of monomers). Then it will be explained how cotelomerization has provided new data to prefer a copolymerization mechanism by free monomers.     

Intermolecular potentials with flexible monomers

Most available intermolecular potentials assume rigid monomers. Such an assumption is a reflection of a trivial observation that if monomer degrees of freedom are considered, the dimensionality of an intermolecular potential increases dramatically even for few-atom monomers. This puts strict limits on the sizes of clusters with flexible monomers that can be treated by ab initio methods since the number of grid points needed to fit a potential surface quickly becomes enormous. Most of the literature flexible-monomer potentials were obtained from the so-called site-site rigid-monomer potentials by simply allowing the sites to move with atomic nuclei as the monomers are deformed. This simple atom-following approach has been investigated in the present work, using water dimer and Ar-HF as test systems, and shown to be not adequate. A method has been proposed which uses properties of isolated flexible monomers to improve upon the atom-following approach without performing any dimer calculations outside the rigid-monomer grid. The method is shown to give for Ar-HF a 3D representation of the dispersion energy that should be adequate for HF motion in the ground and first excited vibrational states.     

Self-assembly of Micrometer-long DNA Nanoribbons with Four Oligonucleotides

DNA nanostructures have found widespread applications in areas including nanoelectronics and biomedicine. However, traditional DNA origami needs a long single‐stranded virus DNA and hundreds of short DNA strands, which make this method complicated and money‐consuming. Here, we present a protocol for the assembly of DNA nanoribbons with only four oligonucleotides. DNA nanoribbons with different dimensions were successfully assembled with a 96‐base scafford strand and three short staples. These biotinylated nanoribbons could also be decorated with streptavidins. This approach suggests that there exist great design spaces for the creation of simple nucleic acid nanostructures which could facilitate their application in plasmonic or drug delivery.     

Polymerization of vinyl monomers in the water–1,4-dioxane system containing peroxide and water-soluble polymer

Water-solube polymer (PST) containing triethylenetetramine side chain was prepared by the amination of chloromethylated polystyrene with triethylenetetramine in 1,4-dioxane. The polymerization of vinyl monomers was carried out in the water–organic solvent system containing PST and a very small amount of peroxide. The polymerization of methyl methacrylate proceeded smoothly in the presence of both peroxide and PST. It was found that the polymerization was initiated with the radicals generated by the interaction between hydroperoxide and amino groups of PST. 1,4-Dioxane hydroperoxide showed a high activity for the polymerization of methyl methacrylate. The maximum rate of the polymerization was observed at 60°C and in an approximately neutral solution. The addition of suitable amount of Cu(II) accelerated the polymerization of methyl methacrylate. The selective polymerization of vinyl monomers was observed in this system.     

Telomerization of acrylic monomers with iodoform

Conclusions Together with dimethylformamide, iron pentacarbonyl initiates the telomerization of acrylonitrile, methyl acrylate, and methyl methacrylate with iodoform, resulting in the formation of telomeric homologs of the series CHI₂(CH₂CRI)_nR and CHI₂(CH₂CHR)_nR (n=1, 2; R=H, CH₃; R=CN, COOCH₃).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2284–2287, October, 1985.     

Oligonucleotides Containing Disaccharide Nucleosides

Disaccharide nucleosides with 2′‐O‐(D ‐arabinofuranosyl), 2′‐O‐(L ‐arabinofuranosyl), 2′‐O‐(D ‐ribopyranosyl), 2′‐O‐(D ‐erythrofuranosyl), and 2′‐O‐(5‐azido‐5‐deoxy‐D ‐ribofuranosyl) substituents were synthesized. These modified nucleosides were incorporated into oligonucleotides (see Table). Single substitution resulted in a ΔT_m of +0.5 to −1.4° for DNA/RNA and a ΔT_m of −0.8 to −4.7° for DNA/DNA duplexes. These disaccharide nucleosides can be well accommodated in RNA/DNA duplexes, and the presence of a NH₂−C(5″) group has a beneficial effect on duplex stability.     

Photochromic Nucleosides and Oligonucleotides

Photochromism is a reversible phenomenon wherein a material undergoes a change in color upon exposure to light. In organic photochromes, this effect often results from light-induced isomerization reactions, leading to alterations in either the spatial orientation or electronic properties of the photochrome. The incorporation of photochromic moieties into biomolecules, such as proteins or nucleic acids, has become a prevalent approach to render these biomolecules responsive to light stimuli. Utilizing light as a trigger for the manipulation of biomolecular structure and function offers numerous advantages compared to other stimuli, such as chemical or electrical treatments, due to its non-invasive nature. Consequently, light proves particularly advantageous in cellular and tissue applications. In this review, we emphasize recent advancements in the field of photochromic nucleosides and oligonucleotides. We provide an overview of the design principles of different classes of photochromes, synthetic strategies, critical analytical challenges, as well as structure–property relationships. The applications of photochromic nucleic acid derivatives encompass diverse domains, ranging from the precise photoregulation of gene expression to the controlled modulation of the three-dimensional structures of oligonucleotides and the development of DNA-based fluorescence modulators. Moreover, we present a future perspective on potential modifications and applications.     

De Novo Design of Functional Oligonucleotides with Acyclic Scaffolds

In this account, we demonstrate a new methodology for the de novo design of functional oligonucleotides with the acyclic scaffolds threoninol and serinol. Four functional motifs—wedge, interstrand‐wedge, dimer, and cluster—have been prepared from natural DNA or RNA and functional base surrogates prepared from d ‐threoninol. The following applications of these motifs are described: (1) photoregulation of formation and dissociation of a DNA duplex modified with azobenzene, (2) sequence‐specific detection of DNA using a fluorescent probe, (3) formation of fluorophore assemblies that mimic quantum dots, (4) improved strand selectivity of siRNA modified with a base surrogate, and (5) in vivo tracing of the RNAi pathway. Finally, we introduce artificial nucleic acids (XNAs) prepared from d ‐threoninol and serinol functionalized with each of the four nucleobases, which have unique properties compared with other acyclic XNAs. Functional oligonucleotides designed from acyclic scaffolds will be powerful tools for both DNA nanotechnology and biotechnology.     

Construction of biological flame retardant layer on cotton fabric via photografting of nucleotide/amino acid monomers

Cellulose - The adenine nucleotide (AMP-Na2) was modified to introduce unsaturated double bonds for photografting onto cotton fabrics together with l-Cysteine (l-Cys) monomer to prepare synergistic...     

1,4-Dihydro-1,4-diphosphinine fused with two tetrathiafulvalenes

Electrochemical and theoretical investigations demonstrate through-bond interactions between two TTF moieties fused to a 1,4-dihydro-1,4-diphosphinine, for which the single crystal X-ray structure of the cis isomer is described together with that of a mixed-valent, charge-localized, radical cation salt with Mo6O19(2-), obtained upon electrocrystallization of the same cis isomer.     

Sulfur-containing vinyl monomers. XIII. Cationic copolymerizations of vinyl sulfides with some vinyl monomers

Cationic copolymerizations of vinyl sulfides (VS) with some vinyl monomers with boron tri-fluoride-diethyl etherate catalyst were investigated to evaluate their monomer reactivities. The effects of VS on the copolymer yield and viscosity of the resulting copolymers revealed the inhibition or retardation mechanism which was explained in terms of the formation of a stable vinylsulfonium salt by the reaction between a propagating carbonium ion and VS monomer. From the results of copolymerizations of phenyl vinyl sulfide (PVS) with isobutyl vinyl ether (IBVE), β-chloroethyl vinyl ether (CEVE), α-methylstyrene (α-MeSt), and styrene (St), the relative reactivities of these monomers were found to be in the following order: IBVE > CEVE > PVS > α-MeSt > St. The relatively higher reactivity of PVS than St derivatives was explained on the basis of the conjugative and electron-donating nature of the VS monomer. The effects of alkyl and para-substituted phenyl groups in vinyl sulfides on their reactivities toward the propagating carbonium ion were correlated with polar factors and compared with those of the hydrolysis of α-mercaptomethyl chlorides. The transition state for the propagation reaction in cationic polymerization of VS was proposed to be a π-complex type structure.     

Molecular imprinting using monomers with solid-state polymerization

Molecular imprinting of two diolefinic compounds with solid-state photopolymerization, 2,5-distyrylpyrazine (DSP) and diethyl p-phenylenediacrylate (EPA), was demonstrated. Solid nanoscale particles of the monomer were produced and deposited onto the surface of a surface acoustic wave (SAW) transducer using the technique known as rapid expansion of supercritical solutions (RESS). The particles were polymerized by UV light in the presence of an alkane template vapor. Both imprinted and non-imprinted devices were tested upon exposure to a variety of alkane vapors in the gas phase. The results demonstrate an enhanced sensitivity to vapors at or below the size of the template. A size exclusion mechanism of recognition is proposed.     

Mixtures of lattice polymers with structured monomers

The influence of monomer structure on the thermodynamic properties of lattice model polymer blends is investigated through Monte Carlo computations. The model of lattice polymers with monomer structure has been used extensively in the context of the lattice cluster theory (LCT), a thermodynamic theory for polymer mixtures in the liquid state. The Monte Carlo computations provide the first unequivocal test of the accuracy of the LCT predictions for binary mixtures of polymers with structured monomers. Four types of monomer structures are analyzed, corresponding to to the monomers of polyethylene, polypropylene, polyethylethylene, and polyisobutylene (PIB). Most computations use chains with M=12 and 24 beads and the total volume fraction of the beads is phi=0.6. Both structurally symmetric and asymmetric blends are investigated. For the symmetric case, the predictions of the LCT for the energies of mixing and the liquid-liquid coexistence curves are in qualitative agreement with the Monte Carlo computations, except for the PIB/PIB symmetric blend. For structurally asymmetric blends, the LCT does not capture contributions to the energy of mixing arising solely from structural differences between the components. Computational estimates of the nonideal entropy of mixing indicate that the LCT also underestimates the entropic cost of mixing chains with different structures, thus explaining some discrepancies between the theoretical and the Monte Carlo liquid--liquid coexistence curves.     

Ni catalyzed ethylene copolymerization with polar monomers

<正>Introduction of polar comonomers into polyethylene is highly challenging, paving the way to tuning the copolymers’ mechanical properties, adhesion/compatibility, and biodegradability. Polar-group tolerant single-site palladium and, more tempting, nickel-based catalysts have demonstrated promising reactivities in the ethylene copolymerization with polar comonomers via coordination/insertion mechanism, providing tighter control of polymer micro-