Theoretical Research And Constructing On A New Double Functional Devices Of Aza-crown Ether

The new double functional molecular devices have been designed and calculated using density functional theory and time-dependent density functional theory.The molecules molecular devices calculated and analyzed theoretically the function of fluorescent sensors and switches.This paper mainly studied the three nitrogen molecular devices,azobenzene embedded N-?11-pyreneyl methyl?-21-crown-7,bipyridine embedded N-?9-pyreneyl methyl?-15-crown-5,styrene embedded N-?9-anthraceneyl methyl?-15-crown-5.According to the results,we have designed three new double functional molecular devices.Firstly,A novel molecular device?trans-azobenzene embedded N-?11-pyrenyl methyl?aza-21-crown-7?with double functional devices was designed on the basis of theoretical calculations.The compounds of a series of alkaline-earth metal cations(Mg²⁺,Ca²⁺,Sr²⁺and Ba²⁺)were investigated.The fully optimized geometries and real frequency calculations were investigated using a computational strategy based on density functional theory?DFT?at B3LYP/6-31G?d?level.Free ligand?L?and their metal cation complexes(L/M²⁺)were studied using mixed basis set(6-31G?d?for the atoms C,H,O and N,and LANL2 DZ for alkaline-earth metal cations Mg²⁺,Ca²⁺,Sr²⁺and Ba²⁺.The natural bond orbital analysis which based on optimized geometric structures was used to explore the interaction of L/M²⁺ molecules.The absorption spectra of L and L/M²⁺,excitation energies and absorption wavelength for their excited states were studied by time-dependent density functional theory?TD-DFT?with 6-31G?d?and LANL2 DZ.A new type molecular device has the selectivity to Ca²⁺ and the emission fluorescence of L/Ca²⁺ under the condition of illumination.This molecule has the double functional device of an allosteric switch and a fluorescent chemosensor.Secondly,theoretical design on a new molecular switch and fluorescent chemosensor double functional device of aza-crown ether?Trans-dipyridine embedded N-?9-anthraceneyl?pyrenyl?methyl?aza-15-crown-5?was explored.Their interaction with a series of alkaline-earth metal cations(Mg²⁺,Ca²⁺,Sr²⁺ and Ba²⁺)was investigated.The fully optimized geometry structures of the free ligand?L1,L2?and their metal cation complexes(L1/M²⁺,L2/M²⁺)were calculated with the B3LYP/6-31G?d?method.The natural bond orbital analysis which based onoptimized geometric structures was used to explore the interaction of L1/M²⁺,L2/M²⁺molecules.The absorption spectra of L1,L2,L1/M²⁺and L2/M²⁺,and their excited states were studied by time-dependent density functional theory?TD-DFT?.A new type molecular device L2?dipyridine embedded N-?9-pyrenyl methyl?aza-15-crown-5?is designed,which not only has the selectivity for Sr²⁺,but also has fluorescent sensor performance.Thirdly,We designed two free ligand?Cis-L,Trans-L?,Cis-L is Cis-styrene embedded N-?9-anthraceneyl methyl?-15-crown-5,Trans-L is trans-styrene embedded N-?9-anthraceneyl methyl?-15-crown-5.Their various parameters and properties of free ligands and the complexes of the alkaline earth metal ions have been calculated using density functional theory and time-dependent density functional theory.Under gas phase condition,the most stable structures and geometric parameters of two ligands have been obtained by the geometry optimization calculation.We analyzed interaction of the alkaline earth metal ions with free ligands by NBO calculation.The HOMO and LUMO distributions and energy gap of the free ligand and the complexes alkaline earth metal ions have been calculated.The ultraviolet absorption spectrum,absorption peak number,maximum absorption peak and excited states of the free ligand and the complexes have been calculated also.According to the above analysis,we have designed a type of fluorescent molecular devices(Trans-L/Ca²⁺).