文摘
[CuLn]2+ and [LnH]+ (L = cytidine) with high relative intensity were observed in the gas phase via electronspray of water and methanol solution of Cu(NO3)2 and cytidine. The possible structures and zero-point energies for the most of these complexes were calculated with DFT methods. The results show that coordination is the main interaction between the L and Cu(II) for [CuLn]2+ (n = 1-4), and the hydrogen-bond between the Ls for [LnH]+ (n = 1-4); the structures for [CuLn]2+ are that the Cu(II) coordinate mostly 4 ligands forming the primary order sphere and other ligands just bind loosely with the primary sphere forming the secondary or outer sphere, and [LnH]+ are that the protonated L dimer composes the primary sphere, and the others binding the dimer loosely form the outer sphere; the calculated stability orders are [CuL2]2+ > [CuL]2+ > [CuL4]2+ > [CuL3]2+ and [L2H]+ > [LH]+ > [L3H]+ > [L4H]+ which are luckily consistent quite well with the peak intensity distribution in the mass spectrum.