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221.
222.
Ukrainczyk M Gredičak M Jerić I Kralj D 《Journal of colloid and interface science》2012,365(1):296-307
Investigation of basic interactions between the active pharmaceutical compounds and calcium carbonates is of great importance because of the possibility to use the carbonates as a mineral carrier in drug delivery systems. In this study the mode and extent of interactions of salicylic acid and its amino acid derivates, chosen as pharmaceutically relevant model compounds, with calcite crystals are described. Therefore, the crystal growth kinetics of well defined rhombohedral calcite seed crystals in the systems containing salicylic acid (SA), 5-amino salicylic acid (5-ASA), N-salicyloil-l-aspartic acid (N-Sal-Asp) or N-salicyloil-l-glutamic acid (N-Sal-Glu), were investigated. The precipitation systems were of relatively low initial supersaturation and of apparently neutral pH. The data on the crystal growth rate reductions in the presence of the applied salicylate molecules were analyzed by means of Cabrera & Vermileya's, and Kubota & Mullin's models of interactions of the dissolved additives and crystal surfaces. The crystal growth kinetic experiments were additionally supported with the appropriate electrokinetic, spectroscopic and adsorption measurements. The Langmuir adsorption constants were determined and they were found to be in a good correlation with values obtained from crystal growth kinetic analyses. The results indicated that salicylate molecules preferentially adsorb along the steps on the growing calcite surfaces. The values of average spacing between the adjacent salicylate adsorption active sites and the average distance between the neighboring adsorbed salicylate molecules were also estimated. 相似文献
223.
Babashkina MG Safin DA Bolte M Garcia Y 《Dalton transactions (Cambridge, England : 2003)》2012,41(11):3223-3232
Ten N-thiophosphorylated thioureas of the common formula RC(S)NHP(S)(OiPr)(2) [R = iPrNH (1), EtNH (2), Et(2)N (3), 2,5-Me(2)C(6)H(3)NH (4), 4-Me(2)NC(6)H(4)NH (5), 2-MeO(O)CC(6)H(4)NH (6), 2-PyNH (7), 2-PyCH(2)NH (8), 3-PyCH(2)NH (9), cyclo-C(2)H(2)N(3)NH (10)] have been synthesized and characterized by IR, NMR spectroscopy and elemental analysis. Molecular structures of 1 and 4-8 were elucidated by X-ray diffraction revealing linear, bi- or trifurcated intramolecular hydrogen bonds. Additionally, their crystal structures are stabillized by two intermolecular hydrogen bonds, which in turn lead to a centrosymmetric dimer formation. The hydrogen bonded dimers of 5-8 are packed to polymeric chains through the π···π stacking interactions between aryl or pyridyl rings. Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using 2-6 and 8-10 as the ionophore present in the organic phase. The source phase contained equimolar concentrations of Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II) and Pb(II) with the source and receiving phases being buffered at pH = 5.5 and 1.0, respectively. The obtained data were compared with the transport and extraction properties of 1 and 7, which were described recently. 相似文献
224.
Li Z Yan M Li Z Vuki M Wu D Liu F Zhong W Zhang L Xu D 《Analytical and bioanalytical chemistry》2012,403(5):1373-1384
The estrogen receptor (ER) is regarded as a significant drug target because of its important physical and pathological function.
In this article, we describe a novel screening method to obtain agonists and antagonists of ER. ER was immobilized onto an
aldehyde-modified glass slide. The affinity of Cy3-labeled estradiol for ER protein microarrays was then determined. Two libraries,
one containing 29 synthetic compounds and the other with 384 natural products that served as a model, were screened to find
new ligands for ER. The IC50 values obtained for tamoxifen and raloxifene were consistent with those found in the literature (4.85 × 10−7 M versus 1.74~4.23 × 10−7 M and 7.58 × 10−8 M versus 0.89~5.84 × 10−8 M, respectively). Finally, 65 active ligands (5 synthetic compounds and 60 natural products) of ER were identified. This
novel method gave identical results to a conventional fluorescence polarization assay, thus verifying the accuracy of this
simultaneous multireceptor screening method based on protein microarrays. The presented method is sensitive, accurate, and
reliable, and shows great potential for use in high-throughput drug-screening research. 相似文献
225.
Veronika Kovač Mojca Čakić Semenčić Krešimir Molčanov Igor Sabljić Damir Iveković Mladen Žinić Vladimir Rapić 《Tetrahedron》2012,68(38):7884-7891
The synthesis and conformational analysis of dimer Fc–CO–NMe–CO–Fc (5) and trimer Fc–CO–NMe–CO–Fn–CO–NMe–CO–Fc (6) have been described. It has been shown by means of spectroscopic studies, X-ray crystallography, and molecular modeling, that these molecules are dominated by cis–cis conformation. Furthermore, we recognized for the first time, that such type of organometallics possess elements of chiral helicity. Their crystal lattices are characterized by π–π and CH–π intermolecular interactions (5) and by CH?OC intermolecular hydrogen bonds (6). We believe that foldamers 5/6 are stabilized by the special type of aromatic π–π interactions between the closer cyclopentadienyl rings of the juxtaposed ferrocene units. 相似文献
226.
Niko S. Radulovi? Goran A. Bogdanovi? Polina D. Blagojevi? Vidosav S. Deki? Rastko D. Vuki?evi? 《Journal of chemical crystallography》2011,41(4):545-551
Abstract
X-Ray analyses of 4-(naphthalen-1-ylamino)-3-nitro-chromen-2-one and 3-nitro-4-phenylamino-chromen-2-one showed that the mentioned compounds crystallize in the space groups P1- (triclinic crystal system; unit cell parameters: a = 8.087(2) ?, b = 9.241(3) ?, c = 10.911(3) ?, α = 93.77(3)°, β = 102.51(3)°, γ = 106.44(2)°, V = 756.4(4) ?3 and Z = 2) and P212121 (orthorhombic crystal system; unit cell parameters: a = 4.9274(9) ?, b = 14.725(3) ?, c = 17.866(4) ?, α = β = γ = 90°, V = 1296.3(5) ?3 and Z = 4), respectively. The analyses of crystal structures and gas phase conformations, inferred from single X-ray crystallographic and molecular modeling experiments, respectively, showed that the changes in π delocalization of the farmacoactive formal 3-amino-2-nitro-acrylic acid derivatives might explain the observed significant difference of the antimicrobial and antioxidant activities and spectral properties of two 4-arylamino-3-nitro-coumarin derivatives. 相似文献227.
228.
Cedomil Vadla Vlasta Horvatic Damir Veza Kay Niemax 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
The present work is a systematic experimental study of the plasma formation in cesium vapor induced by a continuous laser tuned to the resonance transition 6S1/2–6P3/2. Taking into account the measured absolute population densities of Cs ground and excited state atoms as well as the electron densities derived from Stark broadening of the Cs lines, complete local thermodynamic equilibrium in the laser-produced plasma was found for laser power densities ≈ 10 Wcm− 2 at cesium ground state number densities of about 1017 cm− 3. Direct conversion of the excitation energy or parts of the excitation energy in exothermic collisions of laser-excited atoms is concluded to be the major process for atomic vapor heating and subsequent formation of LTE plasmas. 相似文献
229.
AUMILER Damir 《中国科学B辑(英文版)》2009,52(8):1148-1153
The intersystem crossing and isomerization dynamics of free-Cy3, Cy3-ssDNA, free-Cy5 and Cy5-ssDNA are obtained through simple
analysis of rapid on/off blinking from single molecule fluorescence intensity time-traces and the fluorescence correlation
spectroscopy (FCS). The on- and off-times observed in fluorescence time traces of single cyanine dyes are due to the formation
of the triplet state and isomerization, where both the interaction with DNA and long central polymethine chain of cyanine
dyes increase the barriers of isomerization, leading to long off-time. The results indicate that the single molecule fluorescence
fluctuation together with the resulting second autocorrelation analysis are powerful methods for determining the triplet state
and isomerization dynamics, which could be the simple techniques and complementary to other spectroscopic techniques, such
as fluorescence decay measurement and laser flash photolysis to study the photophysical processes of complex molecules.
Supported by the National Natural Science Foundation of China (Grant Nos. 20773139, 20833008 & 20825314), and State Key Project
for Fundamental Research (Grant Nos. 2006CB806000 & 2007CB815200) 相似文献
230.
This paper is a continuation of our study of the inverse monodromy problem for canonical systems of integral and differential equations which appeared in a recent issue of this journal. That paper established a parametrization of the set of all solutions to the inverse monodromy for canonical integral systems in terms of two continuous chains of matrix valued inner functions in the special case that the monodromy matrix was strongly regular (and the signature matrixJ was not definite). The correspondence between the chains and the solutions of this monodromy problem is one to one and onto. In this paper we study the solutions of this inverse problem for several different classes of chains which are specified by imposing assorted growth conditions and symmetries on the monodromy matrix and/or the matrizant (i.e., the fundamental solution) of the underlying equation. These external conditions serve to either fix or limit the class of admissible chains without computing them explicitly. This is useful because typically the chains are not easily accessible. 相似文献