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11.
Andrea Mosseri Dr. Maria Sancho-Albero Dr. Marilisa Leone Donatella Nava Dr. Francesco Secundo Prof. Daniela Maggioni Prof. Luisa De Cola Prof. Alessandra Romanelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(37):e202200693
Self-assembly of biomolecules such as peptides, nucleic acids or their analogues affords supramolecular objects, exhibiting structures and physical properties dependent on the amino-acid or nucleobase composition. Conjugation of the peptide diphenylalanine (FF) to peptide nucleic acids triggers formation of self-assembled structures, mainly stabilized by interactions between FF. In this work we report formation of homogeneous chiral fibers upon self-assembly of the hybrid composed of the tetraphenylalanine peptide (4F) conjugated to the PNA dimer adenine-thymine (at). In this case nucleobases seem to play a key role in determining the morphology and chirality of the fibers. When the PNA “at” is replaced by guanine-cytosine dimer “gc”, disordered structures are observed. Spectroscopic characterization of the self-assembled hybrids, along with AFM and SEM studies is reported. Finally, a structural model consistent with the experimental evidence has also been obtained, showing how the building blocks of 4Fat arrange to give helical fibers. 相似文献
12.
Lucia De Rosa Rossella Di Stasi Alessandra Romanelli Luca Domenico DAndrea 《Molecules (Basel, Switzerland)》2021,26(12)
Although a plethora of chemistries have been developed to selectively decorate protein molecules, novel strategies continue to be reported with the final aim of improving selectivity and mildness of the reaction conditions, preserve protein integrity, and fulfill all the increasing requirements of the modern applications of protein conjugates. The targeting of the protein N-terminal alpha-amine group appears a convenient solution to the issue, emerging as a useful and unique reactive site universally present in each protein molecule. Herein, we provide an updated overview of the methodologies developed until today to afford the selective modification of proteins through the targeting of the N-terminal alpha-amine. Chemical and enzymatic strategies enabling the selective labeling of the protein N-terminal alpha-amine group are described. 相似文献
13.
We demonstrate a novel kind of polariton four wave mixing oscillation. Two pump polaritons scatter towards final states that emit two beams of equal intensity, separated both spatially and in polarization with respect to the pumps. The measurement of the intensity fluctuations of the emitted light demonstrates that the final states are strongly correlated. 相似文献
14.
Laura M. SanchezÁngel G. Sathicq Jorge L. JiosGraciela T. Baronetti Horacio J. ThomasGustavo P. Romanelli 《Tetrahedron letters》2011,52(34):4412-4416
Wells-Dawson heteropolyacids (H6P2W18O62·24H2O) were used as catalysts in the Hantzsch-like multicomponent condensation reaction with 3-formylchromones as aldehyde component, a β-ketoester and ammonium acetate, under solvent-free conditions at 80 °C. Although the desired products were obtained, functionalized pyridines were the main reaction product and became the alternative route to dihydropyridine ring formation. Based on the proposed mechanisms for the formation of each of the obtained products, the multicomponent reaction was modified to afford only the functionalized pyridines (60-99%). Our procedure represents a clean alternative for the synthesis of several highly functionalized pyridines. 相似文献
15.
A simple, precise and selective procedure for the spectrophotometric determination of carbon disulphide in water is described. The method is based on the quantitative formation of the 1,2,3,4-thiatriazol-5-thiolate ion from carbon disulphide and azide. The specific rate for this reaction at ionic strength 4.0 (NaN3) and 25°C is 8.4·10-3 mol-1 s-1; the kinetic parameters D3H and D3S are 16.7 kcal mol-1 and —14 cal mol-1deg-1, respectively. At the analytical wavelength of 313 nm, the molar absorptivity is 7.27 ·103 l mol-1cm-1. The system obeys Beer's law for 2.3–28.6 g ml-1 of carbon disulphide. The effects of foreign ions are discussed. 相似文献
16.
17.
We investigate experimentally one of the main features of a quantum fluid constituted by exciton polaritons in a semiconductor microcavity, that is, quantum degeneracy of a macroscopic fraction of the particles. We show that resonant pumping allows us to create a macroscopic population of polaritons in one quantum state. Furthermore, we demonstrate that parametric polariton scattering results in the transfer of a macroscopic population of polariton from one single quantum state into another one. Finally, we briefly outline a simple method which provides direct evidence of the first-order spatial coherence of the transferred population. 相似文献
18.
We reply to the comment [Front. Phys. 14(5), 53605 (2019)] by Y. Finkelstein and R. Moreh on our article Front. Phys. 13(1), 138205 (2018). We agree with some of their criticisms about our calculation of the temperature effect on the kinetic energy of hydrogen atoms of supercooled confined water; we also agree with their statement that, in view of the current sensitivity of the technique, possible effects of the liquid–liquid water transition are hardly detected with deep inelastic neutron scattering (DINS). However, we disagree with their use of the translational mass ratio of a single water molecule and, in general, with their underestimation of collective effects. 相似文献
19.
Gustavo Pasquale Diego Ruiz Juan Autino Graciela Baronetti Horacio Thomas Gustavo Romanelli 《Comptes Rendus Chimie》2012,15(9):758-763
Silica gel-supported H6P2W18O62·24H2O is an efficient and recyclable catalyst for the synthesis of biologically important molecules. Several substituted N-sulfonyl-1,2,3,4-tetrahydroisoquinolines and ring analogues can be prepared in very good yields and purity by direct reaction of N-aralkylsulfonamides and sym-trioxane by a Pictet-Spengler reaction in the presence of a catalytic amount of silica gel-supported H6P2W18O62·24H2O. Reactions were performed in a low volume of toluene, at 70 °C and for a short time, typically 15 to 30 min. The title heterocyclic compounds were prepared in very good yields (60%–95%) using the described procedure results in a clean and useful alternative, which has the advantages of a greener methodology with operative simplicity, use of a reusable and non-corrosive solid catalyst, soft reaction conditions, low reaction times, and good yields. 相似文献
20.
This paper is devoted to the functional analytic approach to the problem of construction of Feller semigroups with sticky boundary condition on various spaces of continuous functions, generalizing the previous work. More precisely we construct Feller semigroups corresponding to such a diffusion phenomenon that a Markovian particle moves continuously in the state space, sticking to the boundary. 相似文献