排序方式: 共有45条查询结果,搜索用时 125 毫秒
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J. M. Randazzo A. L. Frapiccini F. D. Colavecchia G. Gasaneo 《International journal of quantum chemistry》2009,109(2):125-134
In this work, we present a method to obtain two‐particle Coulomb Sturmians Functions (CSF) with an expansion in a set of L2 basis functions. In the two‐body case, we recover the exact (discrete) spectrum of the CSFs for negative energies and a discretized approximation for positive ones. Besides, we make use of this method to analyze the two‐independent electron problem as a Generalized Sturmian problem. We propose a discretized version of the wave function in terms of the CSF states, and show that the problem reduces to find numerical coincidences between energy‐dependent eigencharges of the mutually independent one‐electron systems. This expansion methodology includes the continuum information which is lost in the sets used previously in the literature, and is complete when the size of the basis goes to infinity. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 相似文献
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Di Fabio G Randazzo A D'Onofrio J Ausín C Pedroso E Grandas A De Napoli L Montesarchio D 《The Journal of organic chemistry》2006,71(9):3395-3408
CyPLOS (cyclic phosphate-linked oligosaccharides), that is, novel cyclic oligosaccharide surrogates, consisting of two, three, and four phenyl-beta-D-glucopyranoside units, 4,6-linked through stable phosphodiester bonds, were prepared by a straightforward and efficient solid-phase protocol. The assembly of the linear precursors was achieved by standard phosphoramidite chemistry on an automated DNA synthesizer, using a suitably protected 4-phosphoramidite derivative of D-glucose as the building block. For the crucial cyclization step a phosphotriester methodology was exploited, followed by a mild basic treatment releasing the desired cyclic molecules in solution in a highly pure form. The cyclic dimer and trimer were also independently prepared by classical solution synthesis, basically following the same approach. The solution structural preferences of the cyclic dimer and trimer, obtained by detailed NMR analysis, are also reported. 相似文献
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Esposito V Virgilio A Randazzo A Galeone A Mayol L 《Chemical communications (Cambridge, England)》2005,(31):3953-3955
Unprecedented DNA quadruplex structures containing a 3'-3' or 5'-5' inversion of polarity site in the G-tract are presented; the quadruplexes are characterized by different elements of symmetry and glycosidic angle conformations. 相似文献
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Chirality Enhancement of Porphyrin Supramolecular Assembly Driven by a Template Preorganization Effect
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Dr. Massimiliano Gaeta Dr. Domenica Raciti Dr. Rosalba Randazzo Dr. Chiara M. A. Gangemi Prof. Antonio Raudino Dr. Alessandro D'Urso Prof. Maria E. Fragalà Prof. Roberto Purrello 《Angewandte Chemie (International ed. in English)》2018,57(33):10656-10660
Cationic polylysine promotes, under neutral conditions, the spontaneous aggregation of opposite charged ZnTPPS in water. Spectroscopic investigations evidence a different preorganization of ZnTPPS onto the polypeptide matrix depending on the chain length. Spinodal decomposition theory in confined geometry is used to model this mechanism by considering the time evolution of a homogeneous distribution of randomly adsorbed particles (porphyrins) onto a rodlike polyelectrolyte (polymer) of variable length L. 相似文献
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Petraccone L Pagano B Esposito V Randazzo A Piccialli G Barone G Mattia CA Giancola C 《Journal of the American Chemical Society》2005,127(46):16215-16223
PNA-DNA chimeras present the interesting properties of PNA, such as the high binding affinity to complementary single-strand (DNA or RNA), and the resistance to nuclease and protease degradation. At the same time, the limitations of an oligomer containing all PNA residues, such as low water solubility, self-aggregation, and low cellular uptake, are effectively overcome. Further, PNA-DNA chimeras possess interesting biological properties as antisense agents. We have explored the ability of PNA-DNA chimeric strands to assemble in quadruplex structures. The rate constant for association of the quadruplexes and their thermodynamic properties have been determined by CD spectroscopy and differential scanning calorimetry (DSC). Thermal denaturation experiments indicated higher thermal and thermodynamic stabilities for chimeric quadruplexes in comparison with the corresponding unmodified DNA quadruplex. Singular value decomposition analysis (SVD) suggests the presence of kinetically stable intermediate species in the quadruplex formation process. The experimental results have been discussed on the basis of molecular dynamic simulations. The ability of PNA-DNA chimeras to form stable quadruplex structures expands their potential utility as therapeutic agents. 相似文献