Ionizable feature

Fig. 11.7 Collisionally induced diabatic ionization features observed following collisions of laser-excited Xe 31f atoms with Xe target gas at a pressure of 1(T5 Torr for 8 fis in the presence of several applied static fields. The arrows indicate the ranges of ionizing field strengths over which n = 30 and 31 states are expected to ionize diabatically (from ref. 43).

Fig. 11.14 Field ionization signal when the Xe 27f state is populated as a function of ionizing field strength (a) without NH3, (b) with 10 5 Torr NH3. The resonant rotational NH3 transitions are indicated beneath each field ionization feature (from ref. 63).

A sphere with a tolerance radius of 1.5 A represents an ionizable feature and is added for the case that a reversely charged ionizable feature can be found on the macromolecule side within a plausible distance range. This interval is set to 1.5-5.6 A and is user-adjustable. 

Point features are rendered as spheres with different colors to differentiate them (Fig. 6.5) hydrophobic/lipophilic features are drawn in yellow and positive and negative ionizable features are drawn in red and blue, respectively. Excluded volume spheres use a dark gray color to signify their meaning. 

HY) as possible features. Two additional constraints were set (i) because of the molecular flexibility and functional complexity of the training set, only pharmacophores containing five features should be considered and (ii) the program was forced to include a positive ionizable feature in the composition of hypotheses, on the basis of the literature reporting a basic atom (usually a nitrogen) as a critical structural determinant for arAR antagonistic activity. 

Ranking function Its internal scoring function depends on the displacement in the alignment of the input molecules and the uniqueness of the pharmacophore (e.g. other things being equal, a positive ionizable feature is more unique than a hydrophobe feature). 

The Negative Ionizable feature was augmented to map on N-acylamides (0=C-NH-C=0) motif such as in Quis (Fig. 15.6a). 

Some recent examples of user-customized features include extended negative ionizable features including sulfonamides, Michael acceptor features for covalent addition, zinc ion binding features, and extended positive ionizable features that can map carbocation intermediates. ... 

Local pharmacophore models have also been generated around narrow structural series such as the sertindole analogues [30], For example, publications containing [3H]-dofetilide binding data for the 5ffT2A class of molecules [44,45], and 3-aminopyrrolidinone farnesyltransferase inhibitors [46], have been used to produce individual pharmacophores that were ultimately combined to suggest common areas of positive ionizable features and hydropho-bicity from aromatic rings [31,47],... 

It is worthwhile to point out that clean Ag has two weak Auger features at 50 and 80 eV (measured in this work), respectively, which are very close to a Li CW feature at 52 eV and a Li doubly ionized feature at 80 eV. A similar problem occurs in the XPS spectra of clean Ag. A Ag 4p XPS feature at 58 eV is very close to a Li Is peak at 54.7 eV. Moreover, the sensitivity factors of the Li Auger and photoelectron emissions are an order of magnitude smaller than those associated with Ag. This made the detection of low coverages of Li (submonolayers) on the Ag surface very difficult. For multilayer Li films relevant to this work, however, Li features dominated the spectra and the Ag features were noticeably attenuated. 

---