The Theoretical Study For The Properties Of Common Molecular In Terms Of Molecular Face And Fukui Function

The properties of molecule have a close relationship with the shape and size,and there are a lot of papers focusing on them.Recently,Yang et al have proposed a method which is named molecular face theory to well describe the shape and size.Molecular face?MF?not only is based on the potential acting on an electron in a molecule,but also is the frontier electron density as a fourth dimension encoded on a three-dimensional molecular intrinsic characteristic counter?MICC?.The D_pbb is an important quantity in the molecular face theory which can indicate the bond strength.In this paper,the D_pb,molecular face,Fukui function et al have been included in this discussion,the related contents are mainly in the three following aspects:1.Rationalization of regioselectivity of electrophilic substitution reaction for cyclic compounds in terms of D_pbb valuesIn this part,all molecular geometries for 32 cyclic compounds used are optimized at MP2/6-311++G?3df,3pd?level of theory,and these PAEMs are calculated by using the MELD ab initio method at SDCI/6-31++G?d,p?level altogether with our own programs.Commonly accepted,the substitution reaction is controlled by the electronic nature of the attacked site for electrophilic aromatic substitution.However,little attention has been paid to the bond strength of the broken bond in the attacked site.Here it is shown that the bond strength of the broken bond may influence the regioselectivity of the substitution reaction by using D_pbb which is a good indicator of the strength of a chemical bond.2.Molecular face and Fukui function mapped on it to indicate the way for electrophilic substitution reactionsAll geometries of the model compounds are optimized at the MP2/6-311++G?d,p?level of theory,using the GUASSIAN03 package programs.The potential acting on an electron in a molecule are obtained by using the MELD ab initio method at the SDCI/6-31++G?d,p?level,and the first vertical ionization energies are obtained at the MP2/6-311++G?d,p?level,respectively.The values of Fukui function are calculated all at the MP2/6-311++G?d,p?level.Not only the graphs of molecular face for 35compounds have been demonstrated,but the distributions of Fukui descriptors on the MFs have been shown as well.These graphs can pictorially and straightforwardly illustrate and elucidate the sites for electrophilic and nucleophilic attack.3.The application of Semi-empirical molecular face method for quickly calculating the D_pbb in situIn this part,nucleoside 3',5'-bisphosphates are chosen as model compounds for DNA and RNA.We have calculated the D_pbb of eight model compounds along C-H chemical bonds by the MELD ab initio method and our own program,and predict the C-H bond strengths.The orders of H-abstraction in DNA and RNA are obtained.For instance,theordersofH-abstractioninDNAandRNAare C1'-H>C2'-H>C4'-H>C5'-H>C3'-HandC1'-H>C4'-H>C5'-H>C3'-H>C2'-H,respectively.The orders render the C1'-H bond of DNA and RNA extraordinarily vulnerable to H-abstraction.This work lays a foundation for future study of H-abstraction in similar systems.All above results are based on the molecular face theory,and the superiority and correctness of it are demonstrated by the results which we have been obtained.What's more,the molecular face theory can also be used in other systems,and it is my further study.