Journal of Physical and Theoretical Chemistry
Volume:6 Issue: 3, Autumn 2009

It is important to determine whether a candidate molecule is capable of penetrating the plasma-brain barrier indrug discovery and development. The aim of this paper is to establish a predictive model for plasma-brainbarrier penetration using simple descriptors The usefulness of the quantum chemical descriptors, calculated atthe level of the DFT and HE theories using 6-310* basis set for QSAR study of anti-vial NucleosideAnalogues drugs was examined. Delivery of anti-viral agents into the central nervous system (CNS) is clmicallyhoportant. Nucleoside analogues are a major source of clinically used antiviral agents. The QSAR modeldeveloped contributed to a mechanistic understanding of the investigated biological effects. The first step in thisstudy was to use a dauset containing 23 drugs with known activity. In the next steps some of them with thelarge secondary chain branches were removed to make our approach. Multiple Linear Regressions (MLR) wasemployed to model the relationships between molecular descriptors and biological activities of molecules usingstepwise method and genetic algorithm as variable selection tools. Biological activities contain the logarithm ofthe ratio of the steady-state concentration of a compound in the brain to in the plasma, log Bp. A multiparametricequation containing maximum six descriptors at HF/6-3 10* and eight descriptors at 133LYP/6-3 10*method with good statistical qualities(Rpax— 0.976 , 11214n— 0.959 at HF/6-3/G* and Rwax4 0.979 , 112KGP 0.952 at B3LYP/6-316*) wasbtiledbyMl(plLR gr g teP thoi Th Sal d d ibis p pe ppears to bevery simple but robust and effective for predictive use This method relates log Bp values to fundamentalmolecular properties, such as Electrostatic Potential. Local charge, Electric Field Gradient, Isotropicparameters, Natural Population Analysis. Also, GA-MLR regression was used to model the structure — activityrelationships.

Cycloaddition reaction between C30 and hula-I, 3-diene was studied within the Snimework of AM I (RHF)level. The reaction involving the double bond between two hexagons and a hexagon and a pentagon, as wellas the cycloaddition products followed by disrotatory ogs s electrocyclic ring openings were considered.Thermodynamics parameters and stability energy and innsation state are evaluated in three Valence isomers

The complexive abilities of 5,11,17-tddert-butyl-23 amino-25.26,27,28-tet3propoxy-calix[4]arere and5,1127-tri-amino-23 acelyktert-butylamide-25,26,27,28-tetrabutoxy-calixplarene towards alkali metalions Lit Nat, Kt RIC and Cs+ in methanol-chloroform mixture have been evaluated at 25 °C, using UVVis spectrophotometric techniques. The results showed that the hgands are capable to complex with all ofthe alkali cations by LI metal to ligand ratios The selectivity presented considering the calculatedformation constants are in the order Li* > Na > C, Kb+ > Cs for the ligands

Geometrical structure, nuclear magnetic resonance (N1,1It) chemical shielding tensors, and chemical shiftsof silicon and carbon nucler are investigated for twn infinite size zigzag and armchair single-walled siliconcarbide nanotabes (SiCNTs). Geometrical structures of SieNTs, Sit bonds and bond angles of St and Cvertices in both zigzag and armchair nanotubes, Indicate that bond lengths are approximately constant inthe armchair model but vary in the zigzag model. The NAIR parameters of C nuclei change more in thezigzag model as compared to the armchair model in agreement with geometrical structure changea. Thecalculations were performed with H3LYR OFT method and 6-310 (d) standard basis sets using theGaussian 03 package.Gaussian 03 package.

In this theoretical study, we focus on a kind of danunarane sapogenins. This molecule optimized in venoussolvent media such as heptao, carbontetrachloride, toluene. tetrahydrofurane, dichloroethane, ethanol, methanol,dimethylsulfoxide and water using the self-consistent reaction field model. This process depends on either thereaction potential function of the solvent or charge transfer operators that appear in solute-solvent interaction.We performed nenemphical quantum-mechanical calculations at the HP3-21.0. 6-310, 6-31G.6-310** andB3LYW6-310" levels of theory in the gas phase and some solvents at 298K.We studied about energy ,dipolemoment ,charge and so on.

In order to find the susceptibility of the Claisen rearrangement and next proton shift reaction of ally) aryl etherto the substiment effects in pan position, the kinetic and the:rmodynamie parameters are calculated at The33 LTP level using 6-3110. b asis set. The calculated activation energies for the rearrangements and protonshift reactions are around 3133 kcaUmol and 52.16 kcal/mol, nap.. lively. Negative values for the activationentropy confirm the concerted mechanign for the Claisen rearrangement and proton shift reaction. TheHammett p value of -1.3433 obtained in Claigen rearrangement. Negative Hammett p value indicate, that theelectron donating groups slightly increase the rate of Claisen rearrangement. Positive Hammett p value (2.5132)for proton shift reaction indicates that electron withdrawing coups increase the rate of reaciion.

Spectropholornetrie technique is used to evaluate binding of the vanadium(1U) ion to a water solublecaruc[4] arene molecule in aqueous solution. On the basis of the calculated value formation constant at25rC.we found that the eomplexation of this metal on is very favored towards 25, 26, 27, 2Stetrahydroxy-5, 11, 17, 23-tetnmulphonalic acid-calix[0]areneGaussian 03 package.

Using C2H2, 112 and As gases at 550'C, carbon nanotubes were fabricated on the surfaces of twosubstrates coated by nano thin layers of metal catalysts by DC magnetron sputtering. AYStamless steel andFe/CteAl, by thermal chemical vapor deposition (TCVD) The surface properties of the substrates wereparticularly investigated, and the effect of treatment of the substrates on the CNT's growth is criticallyanalyzed. It was found that carbon nanotubes (CNTs) formation significantly depends on substrates andcatalysts. GNPs with nano helical( spiral, nano rope struchtres and small amount of amorphous carbon aresuccessfully grown on Fe/Cu/Al. CNTs with nano wall structure gown on AL/Steel. The details ofmorphology of carbon nanotubes are discussed through scanning electron microscope (SEM) and romanspectroscopy. The surface roughness of the deposited of Fe/Cu bilayer and Al as catalysts are discussedthrough atomic force microscope (AFM).

Up to now, various empty carbon fullerenes with different magic number "n", such as C10, Cow Cm, Cso,Cis** Cm and so on. have been obtained. The calix[n]arenes are a class of chalice-like rnacrocyclicmolecules that have attracted widespread attention as complex molecules with liquid crystal behaviors.These classes of compounds are cyclic ohgomers synthessid by condensation of a para-alkylated phenoland formaldehyde. Quantitative structural relationships have been successfully used to construct effectiveand useful mathematical methods for finding good relationships between structural data and the variouschemical and physical properties. To establish a good structural relationship between the structures offidlerenes C, (n 60, 70, 76, 82 and 86) with p-sulfonated calix[8]arene as supramolecular Brysulfonatedcalix[8]azeneTDIC„) complexes was utilized the number of carbon atoms of the fullerenes "n". In thisstudy, the relationship between number of carbon atoms and the four free energies of electron transfer(40„,7) to 4Gry.0) as assessed using oxidation reduction equation between fullerenes C„ (n 4 60, 70, 76. 82and 86) 1-5 and p-sulfonated ealixI8larene (6) as [P-sulfonated calirltiIarene]@IBti surranteltenarcomplexes (A-E) are presented. The results were extended to calculate she four free energies of electrontransfer (alGtiti, to <1.G.,,4)) of other supramolecular complexes for fullerenes Ctis to Cm, and p-sulfonatedcalm [8] arenes A-I to 4-1.

Polycyclic Aromatic Hydrocarbon (PAH) plays an important role in the formation of combustion-generatedparticles such as soot, and their presence in atmosphere aerosols has been widely shown. The formation of five-membered rings, detected in combustion effluent, is of great interest due to their genotoxic activity.The present study reports an investigation of the electronic structure of Acenaphthylene by use of differentchemical models ..We also made a comparison between different chemical models.Donor-acceptor disubstituted, enthalpy, entropy and rotation and transition division function at Zero pointenergy wiD be compared mu.The isotropic and anisotropic tensor of the Acenaphthylene structure were calculated with different chemicalmodels HT /6-31(i*, HF16-31i-G*, HF/6-1 -.Gm% BLYP/6-31 G^, BLYPi6-31+62, BLYP/6-31-fiffm,B3LYIN6-316*, B3LYP/6-31.G. and B3LYP(6-31-H-0**, as well.