A comparative study of proton conduction between two new Cd(II) and Co(II) complexes and in vitro antibacterial study of the Cd(II) complex

Abstract

Two new complexes based on 4,4′‐[1,3‐phenylenebis(oxy)]diphthalic acid (H 4 L) ligands were synthesized, namely, [Cd 2 (L)(1,10‐phen) 2 (H 2 O)] n ( 1 ) and [Co 2 (L)(1,10‐phen) 2 (H 2 O)] n ( 2 ), in which 2D structures transform into 3D supramolecular structures by CH···π interaction. The proton conductivity of complexes 1 and 2 at low temperature is close (σ 1 = 3.12 × 10 −8 S cm −1 and σ 2 = 3.81 × 10 −8 S cm −1 at 30°C), but these two complexes show different conduction mechanisms. The Vehicular mechanism in 1 is caused by the O···H/H···O contact in 1 , which is stronger than 2 , and the Grotthuss mechanism in 2 is caused by the N···H/H···N contact in 2 , which is stronger than 1 . At the same time, complex 1 showed excellent antibacterial properties in vitro, mainly reflected in that five kinds of bacteria ( Escherichia coli , Bacillus amyloliquefaciens , Pantoea agglomerans , Pseudomonas putida , and Pectobacterium carotovora ) could play an obvious inhibitory effect in the concentration range of 20 μg·ml −1 .