Tuning the Binding Energy of Surfactant to CdSe Nanocrystal: A Theoretical Study

The effect of substituent group on the binding energy of phosphonic and carboxylic acids to the Cd6Se6 cluster was studied within density functional theory. The binding energies of 12 para-substituted phenylphosphonic acids, 5 para-substituted benzoic acids, and 5 para-substituted benzoates to the Cd6Se6 cluster were calculated. For all the three types of surfactants, a linear correlation was observed between the calculated binding energy and the substituent constant of the functional group. Electron-donating groups increase the binding energy, while electron-withdrawing groups decrease it. The range of binding energy one can adjust by changing the functional group is about 3 kcal mol(-1) for both phenylphosphonic acids and benzoic acids and about 12 kcal mol(-1) for the benzoates. Such tunability of the surfactant binding energy offers a novel method to control the nucleation and growth kinetics of CdSe nanocrystals.