Study Of The Relativity Between The Capability Of Mercapto-azobenzenes Photocatalytic Degradation And Molecular Structure

Nowadays mercapto-azobenzenes is used popularly in molecular devices. This paper studies on the photocatalytic degradation of TiO2 in mercapto-azobenzenes with different substituents and the structure of electron of composed products by the way of computational methods of quantum chemistry, and then analyses relativity of structure of electron of mercapto-azobenzenes to the photocatalytic degradation of TiO2 .For the different type of substituents, we design mercapto-azobenzenes by the matrix , R=(-CH3,-OCH3,-SH,H,-SO3H,-COOH),and compose the corresponding target molecule.We find that the photocatalytic degradation of TiO2 in mercapto-azobenzenes is the best when the ph of solution is 8, dosage of activator TiO2 is 2.0g/L, concentration of H2O2 is 4mmol/L and the temperature is 200C. Under those conditions we finish this experiment.Making POP as the keyword,by the way of B3LYP in the programme Gaussian03(7.0),at the level 6-31G** , we compute structure of electron of mercapto-azobenzenes and the salvation state of compound in water when SCRF as the keyword. Using the way of time-dependent density functional theory TD-B3LYP at the level 6-31G**, we also compute electronic spectrum of mercapto-azobenzenes.As a result of the above, we know some relativities of different substituents to photocatalytic degradation rate of mercapto-azobenzenes. They are substituents with electron-withdrawing enlarging dipole moment of the molecule, minishing energy gap HLG of the molecule HOMO-LUMO, increasing length of the bond Ph-C and reducing the excitated energy of electrons. Comparing to the matrix , photocatalytic degradation rate of this kind of molecule increases. On the other way round, substituents with electron-pushing reduces photocatalytic degradation rate of mercapto-azobenzenes.the research manifests that the causes and mechanism of photocatalytic degradation rate differentia caused by substituents can be infered by the relativity between photocatalytic degradation of mercapto-azobenzenes and molecular structure through molecular structure parameter, the further study of which can provide helpful theory for the research and application of photocatalytic degradation.