Structures of N,N′,N′′-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide and its nano-scopic zinc(II) coordination ring and their interaction with calf thymus DNA
摘要:
N,N,N ''-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide monohydrate 3-TPB-H2O and an unprecedented cyclic dimeric oligoamide zinc complex [Zn-2(3-TPB)(2)Cl-4]center dot 2H(2)O (1) have been synthesized and their crystal structure were reported. Different from anhydrous 3-TPB, which is s-conformation, 3-TPB center dot H2O adopts aas-conformation. All amide hydrogen form H-bonds. Zn ion in dimeric [Zn-2(3-TPB)(2)Cl-4]center dot 2H(2)O located in a tetrahedron coordination environment. Two 3-TPB ligands and two Zn(II) ions link alternatively to form a 28-membered ring. The Zn center dot center dot center dot Zn distance in the ring is 11.162(5) angstrom. One pyridine nitrogen atom is free. The nano-size macrocyclic framework of 1 is stable up to 390 degrees C. 3-TPB-H2O and complex I have similar fluorescence emission similar to 450 nm. Fluorescence titration shows that calf thymus DNA can quench the fluorescence 3-TPB in aqueous solution. However, calf thymus DNA has no interaction with complex 1. (C) 2008 Elsevier B.V. All rights reserved.