Zn II –Dipyridylamide‐Based Coordination Frameworks: Structural Transformation and Anion Effect

We have synthesized a series of 1 D double‐zigzag ({[Zn(paps) 2 (H 2 O) 2 ](PF 6 ) 2 } n  ( 1 ), {[Zn(papo) 2 (H 2 O) 2 ](PF 6 ) 2 } n  ( 3 ), and {[Zn(papc) 2 (H 2 O) 2 ](PF 6 ) 2 } n  ( 5 )) and 2 D polyrotaxane ([Zn(papc) 2 (PF 6 ) 2 ] n  ( 6 )) frameworks through the reaction of Zn(PF 6 ) 2 with dipyridylamide ligands ( N , N ′‐bis(pyridylcarbonyl)‐4,4′‐diaminodiphenyl thioether (paps), N , N ′‐bis(pyridylcarbonyl)‐4,4′‐diaminodiphenyl ether (papo), and N , N ′‐(methylenedi‐ p ‐phenylene)bispyridine‐4‐carboxamide (papc), respectively), and their molecular structures have been determined through X‐ray diffraction studies. From the powder X‐ray diffraction (PXRD) experiments, it is found that on heating, the double‐zigzag frameworks 1 and 3 undergo structural transformation to give the respective polyrotaxane frameworks 2 ([Zn(paps) 2 (PF 6 ) 2 ] n ) and 4 ([Zn(papo) 2 (PF 6 ) 2 ] n ), which matched well with those of their Zn(ClO 4 ) 2 analogues. Furthermore, grinding the solid samples of 2 and 4 in the presence of moisture resulted in total conversion back to the double‐zigzag frameworks 1 and 3 , respectively. Although the 1 D double‐zigzag and 2 D polyrotaxane frameworks of Zn II ‐paps and ‐papo with ClO 4 − anions can be also interconverted through heating and grinding in the presence of moisture, the related Zn II ‐papc framework with ClO 4 − can only undergo a structural transformation process through heating. Surprisingly, reversible structural transformation between 5 and 6 has been proven successfully. In this work, we show that by replacing ClO 4 − with PF 6 − , a series of Zn II ‐pap x ‐based frameworks can be obtained. Significantly, this indicates that a remarkable anion effect on such a novel structural transformation process has been demonstrated.