The Method Of Establishing Topological-Quantum Bond Adjacency Matrix And Its Application In The QSPR/QSAR Study For Organic Compounds

The postulation that the molecular structure of a compound predetermines its properties is a universal principle in chemistry.One of the fundamental and hot issues in chemistry is how to establish quantitative structure-activity relationships(QSAR)and quantitative structure-property relationships(QSPR),which have fascinated chemists all along the time.It is commonly believed that the structural formula of a molecule contains all the information determining the physicochemical and biological properties of the molecule.Consequently,a major and crucial task in QSAR/QSPR researches is how to exactly extract sufficient chemical information with numerical format from the chemical formula.In this work,a new method(i.e.,topological-quantum bond adjacency matrix method)was established by introducing the substitutent constants to replace the main diagonal elements of the adjacency matrix. The new matrix can be used to effectively extract structural descriptors, topological-quantum descriptors,for various organic compounds.The topological-quantum descriptors have the merits of topological index(i.e., facility and rapid calculation of parameters)and the advantage of quantum descriptors(i.e.,explicit meaning of parameters)and at the same time make up some disadvantages of the quantum and molecular graph method.Topological- quantum descriptors were applied to the study of QSPR/QSAR for diverse molecules.In all,this dissertation covers five aspects as below:1.In this work,the topological-quantum method was employed to study the properties of alkanes which did not be investigated by our group previously(such as thermal conductivity under different temperatures and C-13 chemical shift)and got good results.2.A method was proposed to establish topological-quantum bond adjacency matrix for the R-X-R'(X is O,S,NH,S-S,or SO₄)molecule as follow:firstly,take the R-X-R' molecule as its corresponding alkane R-CH₂-R';then,refer to the method of establishment of topological-quantum bond adjacency matrix for alkanes to construct the matrix for R-X-R'(X is O,S,NH,S-S,or SO₄)molecule.Along with some other descriptors,the topological-quantum descriptors extracted by topological-quantum bond adjacency matrix were used to build a single QSPR model to predict the boiling points for ten classes of organic compounds,i.e.,R-O-R',R-S-R',R-NH-R',ROH,RCl,RBr,RI,RSH, RCOH,and RCOR'.And the predicted error is 5.4℃.In addition,a QSPR model was got to estimate of the enthalpy of formation for R-X-R'(X is O,S,S-S,or SO₄)and the predicted error s=3.41 kJ/mol is within the experimental error.3.In the present work,we constructed topological-quantum bond adjacency matrix for the alkenes.On the basis of the matrix,some topological-quantum descriptors,e.g.the relative energy of orbitals and atomic charge were calculated and used to correlate with UV absorption wavelength,ionization potential and C-13 chemical shift for alkenes. Some good QSPR models for alkenes were obtained.4.For the aromatic molecule series(including substituted benzenes, phenols,and substituted pyridines),a method was proposed to build the topological-quantum bond adjacency matrix.The topological-quantum descriptors were applied to investigate the structure-property relationship for various physicochemical properties of aromatic molecules,such as ionization potential,chemical shift,enthalpy of formation,enthalpy of atomization,boiling points,retention index,bond dissociation energy of O-H,and n-octanol/water partition coefficient and various biological activity/toxicity,such as EC₅₀,LC₅₀,and IC₅₀.Some good QSPR/QSAR models with high prediction accuracy and easy interpretation for aromatic molecules were obtained.The results of the comparison of the method proposed by this work and the quantum methods such as HF/6-31G^*, DFT-B3LYP/6-31G^* and DFT-B3LYP/6-311++G(p,d)show that the calculated accuracy of our method is similar to the quantum methods for study of the above-mentioned properties.However,the calculated rate of our method is faster than that of the above-mentioned quantum methods.5.For R-(X=O)-R' series(X is N or O),a method was proposed to build the topological-quantum bond adjacency matrix.The topological-quantum descriptors were extracted and applied to investigate UV absorption wavelength of R¹R²C=O,the reaction velocity of NaHSO₃ to R¹R²C=O,and the X=O stretching vibration frequencies in infrared spectra of R¹R²C=O,(RO)₂C=O,RCO₂H,RON=O,and R2NN=O.Some good QSPR models for R-(X=O)-R' were obtained.