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Log Po/w (log + po)
Selected AbstractsRetention of arsenic species on zwitterionic stationary phase in hydrophilic interaction chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6-7 2010Dan Xie Abstract Zwitterionic hydrophilic interaction chromatography (ZIC® -HILIC) was used to study the retention of selected organoarsenicals. The retention behavior of nine organic arsenic species on ZIC® -HILIC was investigated to elucidate which is the driving force for their separation, hydrophilic partitioning or adsorption driven by hydrogen bonds with surface H-donor/acceptor groups of the stationary phase. For this, the retention factor of the compounds k was correlated with log PO/W and with the calculated strength of hydrogen bonding of the analytes. By examining aliphatic and phenylic compounds separately, improved correlation was received. This indicates that both phenomena contribute to the separation of these arsenic species on ZIC® -HILIC. The results obtained evidence that considerable electrostatic interactions also occur on ZIC® -HILIC. Retention behavior of arsenic species was investigated by varying the separation conditions, which shows that the composition of the eluent has a strong influence on the retention behavior. It is highly dependent on water/acetonitrile ratio, pH value and salt additives. Dissociation degree and polarity of arsenic species, which are varying with pH, regulate the distribution of arsenic species between stationary and mobile phases in HILIC. Increase in the ammonium acetate concentration leads to shortened or to prolonged retention depending on the structure of the arsenic species. [source] Prediction of octanol,water partition coefficients of organic compounds by multiple linear regression, partial least squares, and artificial neural networkJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2009Hassan Golmohammadi Abstract A quantitative structure,property relationship (QSPR) study was performed to develop models those relate the structure of 141 organic compounds to their octanol,water partition coefficients (log Po/w). A genetic algorithm was applied as a variable selection tool. Modeling of log Po/w of these compounds as a function of theoretically derived descriptors was established by multiple linear regression (MLR), partial least squares (PLS), and artificial neural network (ANN). The best selected descriptors that appear in the models are: atomic charge weighted partial positively charged surface area (PPSA-3), fractional atomic charge weighted partial positive surface area (FPSA-3), minimum atomic partial charge (Qmin), molecular volume (MV), total dipole moment of molecule (,), maximum antibonding contribution of a molecule orbital in the molecule (MAC), and maximum free valency of a C atom in the molecule (MFV). The result obtained showed the ability of developed artificial neural network to prediction of partition coefficients of organic compounds. Also, the results revealed the superiority of ANN over the MLR and PLS models. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 [source] A pyrazolylamine-phosphonate monoester chelator for the fac -[M(CO)3]+ core (M = Re, 99mTc): synthesis, coordination properties and biological assessmentJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 13 2007Elisa Palma Abstract Aiming to develop new strategies for the labeling of hydroxyl-containing biomolecules with the organometallic core fac -[99mTc(CO)3]+, we have prepared a new model bifunctional chelator, L4 (ethyl hydrogen (2-{[2-(3,5-dimethyl-1H -pyrazol-1-yl)ethyl]amino}ethyl)phosphonate), combining a pyrazolyl-amine chelating group and a monophosphonate ethyl ester function (,P(O)OHOEt). The phosphonate group allows metal stabilization, and, simultaneously, can be considered as a potential attachment site for a biomolecule. Reaction of L4 with the precursor [99mTc(H2O)3(CO)3]+ gave the model radiocomplex [99mTc(CO)3(k3 -L4)] (6a). This radiocomplex was identified by comparing its chromatographic profile with that of the corresponding Re analog (6) under the same conditions, also prepared and fully characterized by the usual analytical techniques. Radiocomplex 6a is moderately lipophilic (log Po/w = 1.07), presenting high stability in vitro without any measurable decomposition or ligand exchange, even in the presence of strong competing chelators such as histidine and cysteine (37°C, 24 h). Biodistribution studies of the complex in CD-1 mice indicated a rapid blood clearance, and a rapid clearance from main organs, occurring primarily through the hepatobiliary pathway. Complex 6a presents also a high robustness in vivo, demonstrated by its resistance to metabolic degradation in blood, and intact excretion into the urine, after RP-HPLC analysis of blood and urine samples. Copyright © 2007 John Wiley & Sons, Ltd. [source] Determination of lipophilic descriptors of antihelmintic 6,7-diaryl-pteridine derivatives useful for bioactivity predictionsBIOMEDICAL CHROMATOGRAPHY, Issue 6 2003Mario Reta Abstract The liquid chromatographic retention factors extrapolated to pure water, k,w, for several 6,7-diaryl-pteridine derivatives in both an octadecylsilane (ODS) and an immobilized arti,cial membrane column (IAM.PC.DD2), using acetonitrile,aqueous buffer pH = 7.45 as mobile phase, were obtained. The logarithms of the k,w values in the IAM.PC.DD2 column, log k,wIAM, show good correlation with the calculated values of the octanol,water partition coef,cients, log Po/w, showing that the chromatographic parameter can be used as lipophilicity descriptor for the studied pteridines. However, interactions other than the lipophilic ones seem to be involved in the ODS column. Previous studies have shown that pteridines have antihelmintic properties. In spite of the complexity of the studied biological system as compared with the chromatographic one, good correlation between the descriptors obtained in the IAM column and biological activity (expressed as the log of the inhibitory concentration required to obtain up to 50% in the reduction of population growth of nematodes, log IC50) was observed. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||