ZnII -Dipyridylamide-Based Coordination Frameworks: Structural Transformation and Anion Effect
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Updated: Dec 30, 2025

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Biing-Chiau Tzeng1, Chien-Ting Yeh1, Tsung-Yi Chang1
1Department of Chemistry and Biochemistry, National Chung Cheng University, 168 University Rd., Min-Hsiung, Chiayi 62102 (Taiwan R.o.C).
Abstract:
We have synthesized a series of 1 D double-zigzag ({[Zn(paps)2 (H2 O)2 ](PF6 )2 }n (1), {[Zn(papo)2 (H2 O)2 ](PF6 )2 }n (3), and {[Zn(papc)2 (H2 O)2 ](PF6 )2 }n (5)) and 2 D polyrotaxane ([Zn(papc)2 (PF6 )2 ]n (6)) frameworks through the reaction of Zn(PF6 )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 (PF6 )2 ]n ) and 4 ([Zn(papo)2 (PF6 )2 ]n ), which matched well with those of their Zn(ClO4 )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 ZnII -paps and -papo with ClO4 - anions can be also interconverted through heating and grinding in the presence of moisture, the related ZnII -papc framework with ClO4 - 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 ClO4 - with PF6 - , a series of ZnII -papx-based frameworks can be obtained. Significantly, this indicates that a remarkable anion effect on such a novel structural transformation process has been demonstrated.
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