Synthesis And Host-guest Recognition Of Double-Headed Macrocycles Containing Pyridimide And Pyrrole Units

The synthesis of macrocyclic compounds and the study of host and guest recognition have attracted much attention in supramolecular chemistry.In this paper,macrocycles L1,L2,L3 and L4 were synthesized.A Schiff base macrocycle L1 containing pyridine imide group and pyrrole unit and its reductive macrocycle L2,whose double bond(-CH=N-)back into a single bond(-CH2-NH-),were synthesized by precursor diamine A[N,N'-(3-aminophenyl)-2,6-diformimide pyridine]and precursor diamaldehyde B(5,5'-dimethyl-1,9-diformyldipyrrole methane).Another Schiff base macrocycle L3 and its reductive macrocycle L4 were synthesized by C[N,N'-(2-aminophenyl)-2,6-diformimide pyridine]and precursor diamaldehyde B(5,5'-dimethyl-1,9-diformyldipyrrole methane).Li,L2,L3 and L4 were characterized by 1H NMR,IR and MS,and the crystal structures of L1,L2 and L3 were obtained.The coordination reaction of Schiff base macrocycle Li,L3 and their reductive macrocycle L2,L4 with HP2O73-?H2P2O72-ions and H4P2O7 were investigated via UV-Vis spectra technique and the coordination ratio and equilibrium constant were obtained and the bonding effects were further investigated by 1HNMR titration technique.In addition,the host and guest interactions of L1,L2,L3 and L4 with 1,8-ANS were investigated by fluorescence spectrophotometry and the corresponding bonding ratios were calculated.Then,the bonding effects were further investigated by 1HNMR titration technique,too.As a result,Schiff base macrocycle L1 can recognize HP2O73-with the coordination ratios of 2:1 and the bonding constants are Ka1=2.74×104 L·mol-1,Ka2=8.40×105 L·mol-1.L1 also can recognize H2P2O72-,H4P2O7 and 1,8-ANS with the same coordination ratios of 1:1 and the bonding constants are 1.44×107 L·mol-1,1.81×106 L·mol-1?3.06×104L·mol-1 in order.Macrocycles L2 and L3 can recognize four guests with the same coordination ratio of 1:1 and the bonding constants are 5.32×105 L·mol-1,1.47×105 L·mol-1,3.12×105 L·mol-1,6.584×103 L·mol-1;4.36×105 L·mol-1,2.94×105 L·mol-1,1.21×105 L·mol-1,2.53×104 L·mol-,respectively.Moreover,both the coordination ratios of macrocycle L4 with HP2O73-and H2P2O72-ions are 1:1 and the bonding constants are 7.59×105 L·mol-1,1.41×106 L·mol-1,but it has no obvious interaction with H4P2O7 and 1,8-ANS molecules.