Theoretical Study On The Cations Recognition And Interaction Of Crown Ethers Derivatives

In this paper, the molecular recognition of crown ether derivatives with cations are theoretically studied with Density functional theory(DFT). The three systems are as follows:(1)Theoretical study on reactions of crown ether derivatives with amido bond and alkali-metal cations(Li+, Na+, K+);(2)Theoretical study on cations(Li+, Na+, K+,Mg2+, Ca2+and Zn2+) complexation of phenol-crown ether derivatives;(3) Theoretical study on reactions of crown ether derivatives with heterocyclic ring and cations(Li+, Na+,K+, Fe3+, NH4+ and Zn2+).The first part of this paper describes systemically a theoretical research on the interaction of alkali-metal cations(Li+, Na+, K+) with four different crown ether derivatives using density functional theory. These fully optimized geometries have been proved with real frequencies which indicate the minimality states. The optimized structures and electronic properties of the free ligands L(L1-L4), the complexes L/M+(Li+,Na+, K+) have been performed at B3LYP/6-31G(d,p) level. Natural bond orbital and frequency analysis are discussed on the basis of the optimized geometric structures. We also investigated the main driving forces of the coordination in host-guest molecules, the electron-donating O offers lone pair electrons to the contacting LP*(1-center valence antibond lone pair) of alkali-metal cations, biggest absorb wavelength and shock wave.In addition, the transition energies are caculated by TD-DFT.The second part of this paper investigated on the interaction of phenol-crown ether derivatives and cations(Li+, Na+, K+, Mg2+, Ca2+and Zn2+) systemically using density functional theory. The fully optimized geometries have been performed without negative frequencies which indicate the minima states. The optimized structures and electronic properties of the two ligands L(L1-L2), the complexes L/M+(Li+, Na+, K+, Mg2+, Ca2+and Zn2+) have been performed at B3LYP/6-31G(d, p) level. The main driving forces of the coordination in host-guest molecules are studied, the electron-donating O offers lone pair electrons to the contacting LP*(1-center valence antibond lone pair) of cations. The analysis of Natural bond orbital and frequency are discussed on the basis of the optimized geometric structures. The IR spectra informs the interaction of the host-guest molecules. The transition energies are performed by TD-DFT.At the last part, we studied a series of interaction between crown ether derivatives with heterocyclic ring and six kinds of(Li+, Na+, K+, Fe3+, NH4+ and Zn2+).And got the optimized structures and electronic properties. The fully optimized geometries had beenperformed with real frequencies which have indicated the minima states. The structures and coordination numbers of the complexes announced that the best match of the coumarin-15-crown-5 ethers is the cation Na+and cation Li+and at the same time, the best match of the coumarin-18-crown-6 ether derivatives is the cation K+. Natural bond orbital and frequency analysis are discussed on the basis of the the stable conformers of the complexes. We studied the main driving forces of the coordination in host-guest molecules, the electron-donating O offers lone pair electrons to the contacting LP*(1-center valence antibond lone pair) of cations. In addition, the transition energies are studied and got the energy of activated state and the biggest absorb wavelength by TD-DFT.