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71.
Corsaro C Spooren J Branca C Leone N Broccio M Kim C Chen SH Stanley HE Mallamace F 《The journal of physical chemistry. B》2008,112(34):10449-10454
Proton nuclear magnetic resonance (1H NMR) experiments have been performed to measure the spin-lattice, T1, and spin-spin, T2, relaxation times of the three functional groups in water/methanol mixtures at different methanol molar fractions (XMeOH=0, 0.04, 0.1, 0.24, 0.5, 1) as a function of temperature in the range 205 K相似文献
72.
Leone SR 《The journal of physical chemistry. A》2008,112(39):9169-9176
73.
A cyclen derivative bearing a ferrocenyl arm (L) and a series of its ZnII complexes [ZnL(OH2)][ClO4]2 (C1), [ZnL(OH)][ClO4] (C2), and [ZnL(Cl)][ClO4].CH3CN (C3) (cyclen = 1,4,7,10-tetraazacyclododecane, L = 1-(ferrocenemethyl)-1,4,7,10-tetraazacyclododecane) have been prepared and characterized spectroscopically. An X-ray structure determination confirmed the formation of complex C1 and revealed that the coordinated water participates in hydrogen bonding with the perchlorate counter ions. The pKa value for deprotonation of the water molecule determined by potentiometric titration was found to be 7.36 +/- 0.09 at 25 degrees C and I = 0.1 (KNO3). The possibility of using complex C1 as a potential sensor for thymine derivatives in aqueous solution has been examined. Shifts in the 1H and 13C NMR resonances showed the binding occurred with thymine (T) and two thymine derivatives, thymidine (dT) and thymidine 5'-monophosphate (TMP2-). Significant shifts of the nuC=O and nuC=C vibrations of the thymine derivatives were also observed via IR spectroscopy upon complexation with the receptor. The thymine adduct, [ZnL(thymine anion)][ClO4].2H2O (C4), has been crystallized and characterized. The X-ray structure of C4 confirmed the thymine binding to the receptor, and the short Zn-N(thymine) distance of 1.975(5) A indicated clearly that the ferrocenyl arm does not affect the complexation of the DNA base. In contrast to the large spectral changes, electrochemical studies showed a small shift of the reversible potential of the redox couple Fc+/Fc (Fc = ferrocene) and subtle changes in voltammetry upon the addition of an excess of dT, TMP2-, and guanine (dG) at physiological pH, indicating the level of interaction is similar in both Fc and Fc+ forms. 相似文献
74.
Lisa Russelli Francesco De Rose Loredana Leone Sybille Reder Markus Schwaiger Calogero DAlessandria Lorenzo Tei 《Molecules (Basel, Switzerland)》2021,26(19)
In this work, we designed, developed, characterized, and investigated a new chelator and its bifunctional derivative for 89Zr labeling and PET-imaging. In a preliminary study, we synthesized two hexadentate chelators named AAZTHAS and AAZTHAG, based on the seven-membered heterocycle AMPED (6-amino-6-methylperhydro-1,4-diazepine) with the aim to increase the rigidity of the 89Zr complex by using N-methyl-N-(hydroxy)succinamide or N-methyl-N-(hydroxy)glutaramide pendant arms attached to the cyclic structure. N-methylhydroxamate groups are the donor groups chosen to efficiently coordinate 89Zr. After in vitro stability tests, we selected the chelator with longer arms, AAZTHAG, as the best complexing agent for 89Zr presenting a stability of 86.4 ± 5.5% in human serum (HS) for at least 72 h. Small animal PET/CT static scans acquired at different time points (up to 24 h) and ex vivo organ distribution studies were then carried out in healthy nude mice (n = 3) to investigate the stability and biodistribution in vivo of this new 89Zr-based complex. High stability in vivo, with low accumulation of free 89Zr in bones and kidneys, was measured. Furthermore, an activated ester functionalized version of AAZTHAG was synthesized to allow the conjugation with biomolecules such as antibodies. The bifunctional chelator was then conjugated to the human anti-HER2 monoclonal antibody Trastuzumab (Tz) as a proof of principle test of conjugation to biologically active molecules. The final 89Zr labeled compound was characterized via radio-HPLC and SDS-PAGE followed by autoradiography, and its stability in different solutions was assessed for at least 4 days. 相似文献
75.
Glen B. Deacon Pauline Pearson Brian W. Skelton Leone Spiccia Allan H. White 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):m537-m539
The syntheses and crystal structure determinations of a pair of `sawhorse' dimers are reported, viz. [Ru2(C6H5CO2)2(C5H5N)2(CO)4] [a new polymorph, cf. Kepert, Deacon, Spiccia, Fallon, Skelton & White (2000). J. Chem. Soc. Dalton Trans. pp. 2867–2874] and [Ru2(CF3CO2)2(C5H5N)2(CO)4]. The Ru⋯Ru distances are 2.6724 (2) and 2.7122 (5) Å, respectively. 相似文献
76.
Syndiotactic specific polymerization of styrene has been investigated by ~(13)C NMR analysis and isotopic laelling methods. The value of the activation energy involved in the steric control has been determined. Some information of the number of the active sites and on the life of the catalysts is reported. 相似文献
77.
78.
Adam J. Trevitt Fabien Goulay Giovanni Meloni David L. Osborn Craig A. Taatjes Stephen R. Leone 《International journal of mass spectrometry》2009,280(1-3):113
Product detection studies of CN reactions with ethene and propene are conducted at room temperature (4 Torr, 533.3 Pa) using multiplexed time-resolved mass spectrometry with tunable synchrotron photoionization. Photoionization efficiency curves, i.e., the ion signal as a function of photon energy, are used to determine the products and distinguish isomers. Both reactions proceed predominantly via CN addition to the π orbital of the olefin. For CN + ethene, cyanoethene (C2H3CN) is detected as the sole product in agreement with recent studies on this reaction. Multiple products are identified for the CN + propene reaction with 75(±15)% of the detected products in the form of cyanoethene from a CH3 elimination channel and 25(±15)% forming different isomers of C4H5N via H elimination. The C4H5N comprises 57(±15)% 1-cyanopropene, 43(±15)% 2-cyanopropene and <15% 3-cyanopropene. No evidence of direct H abstraction or indirect HCN formation is detected for either reaction. The results have relevance to the molecular weight growth chemistry on Saturn's largest moon Titan, where the formation of small unsaturated nitriles are proposed to be key steps in the early chemical stages of haze formation. 相似文献
79.
A chemoselective, mild, and versatile method for performing postsynthetic modifications of peptide sequences is described. It requires only activated molecular sieves in the presence of an alkyl halide in order to N-alkylate lysine side chains. This reaction is fully compatible with most of the peptide functionalities, discriminates the reactivity of differently protected lysines, and proceeds in good yield. The mild conditions employed were further proved by performing the N-alkylation of a peptide containing a disulfide bridge. 相似文献
80.
Vanja Calija Andrew J. Higgins Phillip A. Jackson Leone M. Bielig Danny Coomans 《Annals of Operations Research》2001,108(1-4):123-142
Selection for superior clones is the most important aspect of sugar cane improvement programs, and is a long and expensive process. While studies have investigated different components of selection independently, there has not been a whole system approach to improve the process. This study observes the problem as an integrated system, where if one parameter changes the state of the whole system changes. A computer based stochastic simulation model that accurately represents the selection was developed. This paper describes the simulation model, showing its accuracy as well as how a combination of dynamic programming and branch and bound can be applied to the model to optimise the selection system, giving a new application of these techniques. The model can be directly applied to any region targeted by sugarcane breeding programs or to other clonally propagated crops. 相似文献