| Based on the excited-state hydrogen bonding dynamics theory, the geometrical structures, electrostatic potential, Mulliken population analyses, UV-Vis absorption spectra, fluorescence spectra and the infrared spectra etc of the three special hydrogen-bonded systems have been studied with the density functional theory(DFT) and time-dependent density functional theory method(TDDFT) in this paper. By analysis of the hydrogen bonding interaction, spectrum shifts, intramolecular charge transfers(ICT) etc before and after photoexcitation, the concrete role of hydrogen bonding and its influence on photophysical and photochemical properties have been discussed in detail.In Chapter 1, the photoexcitation and decay processes as well as the influences of the hydrogen bonding interactions on the photophysical and photochemical properties of molecule systems are discussed firstly, and then the main research contents of the paper are introduced briefly. In Chapter 2, firstly, the quantum mechanics methods are introduced concisely; then the frequently-used quantum mechanics methods to study the electronic structures of multi-electron systems, such as density functional theory method and time-dependent density functional theory method are mainly introduced.In Chapter 3, the different geometrical structures of N-(n-hydroxyethyl)-1,8-naphthalimide(n=2,3;2a,3a) in non-protic and protic solvent were investigated firstly. In the non-protic solvent, there is one intramolecular hydrogen bonding in both 2a and 3a. However, when it comes to the protic solvent, the intramolecular hydrogen bonding in 2a and 3a is disrupted, and three intermolecular hydrogen bonds are formed in the hydrogen-bonded complexes 2a+2meoh and 3a+2meoh in the ground state. It has been demonstrated the little influence of the different substituent on N-hydroxyethyl-1,8-naphthalimide. Upon photoexcitation, the intermolecular hydrogen bonds for 2a+2meoh and 3a+2meoh are slightly strengthened after excitation to the S1 state, and thus induce electronic spectral to red shift. The absorption and fluorescence spectra are also calculated and accord well with the experimental results. Moreover, the ICT properties for 2a and 3a and the localized excitation(LE) properties for complexes 2a+2meoh and 3a+2meoh in the S1 state have been theoretically demonstrated by analysis of molecular orbital.In Chapter 4, the different excited-state hydrogen bonding dynamics behavior of the intramolecular hydrogen bondings N???H-O and N-H???O for compounds based on 2-(2-hydroxyphenyl)-1,3-benzoxazole(6 and its tautomers 6a and 6b) were investigated. In order to improve the calculated spectra with reasonable accuracy and accord well with the experimental results, a number of functional tests have been implemented. It can be concluded that the type of intramolecular hydrogen bonding N···H-O is significantly strengthened, while that N-H···O is sharply weakened upon excitation to excited state S1. In the S0 state, the molecule 6 is more stable, while 6b is the most stable molecule in the S1 state. In addition, by analysis of the compounds that R1 and R2 are both substituted as well as that only R1 is substituted, it is found that the hydrogen bond strength for 6 can be controlled by the inductive field effect of the substituent.In Chapter 5, Esther Vega and coworkers have reported the important influence of hydrogen bond interactions on the adsorption capacity of adsorbent and adsorbate. That is to say, the adsorption ability of ethyl mercaptan(ETM) onto the functionalized activated carbons(AC) has been improved by introducing hydrogen donor group(AC-COOCO,AC-CCC,AC-CO and AC-OH). We mainly focused on the influence of the intermolecular hydrogen bonding dynamics on adsorption of ETM onto functionalized activated carbons in both S0 and S1 state. In the S0 state, it is demonstrated that the stability trend of forming hydrogen-bonded complexes is AC-COOCO-2ETM(I) > AC-CCC-2ETM(II), AC-CO- ETM(III) > AC-OH-ETM(IV), which coincides with the results from the interaction energies calculation EHB. In the S1 state, the hydrogen bond interactions can facilitate ETM adsorption onto AC-COOCO, AC-CCC and AC-CO, respectively. However, the hydrogen bond interaction in complex IV is against ETM adsorption onto AC-OH in the excited state. The photoexcitation for complex IV should be controlled during the absorption process. This provides the theory support for choosing appropriate functional group of AC. |
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