Crystal-engineering and luminescence studies of 1,3,5-tris(3-pyridylethynyl)benzene or 1,3,5-tris(4-pyridylethynyl)benzene with copper() iodides

• Published in: Dalton transactions : an international journal of inorganic chemistry 2019-03, Vol.48 (12), p.446-457
• Main Authors: Tzeng, Biing-Chiau, Lin, Jun-Fu
• Format: Article
• Language: English
• Subjects: Benzene; Charge transfer; Clusters; Copper; Crystallography; Cubane; Hydrocarbons; Hydrogen bonding; Iodides; Ligands; X-ray diffraction
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt04904a

Two isomeric C 3 -symmetric ligands, 1,3,5-tris(3-pyridylethynyl)benzene ( L1 ) and 1,3,5-tris(4-pyridylethynyl)benzene ( L2 ), were used to react with CuI to give a series of coordination frameworks containing various CuI clusters, {[(Cu 2 I 2 ) 2 ( L1 ) 2 ]·C 6 H 5 CH 3 } n ( 1 ), {[(Cu 2 I 2 ) 1.5 ( L1 ) 2 ]·1.5C 6 H 6 ·CH 3 CN} n ( 2 ), [(Cu 2 I 2 ) 0.5 ( L1 )] n ( 3 ), {[(Cu 2 I 2 ) 0.5 ( L2 )]·C 6 H 6 } n ( 4 ), and {[(Cu 2 I 2 )( L2 )]·C 6 H 6 } n ( 5 ), which have been isolated and structurally characterized by X-ray diffraction studies. Although 1 is simultaneously composed of a rhombohedral Cu 2 I 2 cluster and a step-cubane Cu 4 I 4 cluster and 2 contains two types of rhombohedral Cu 2 I 2 clusters in the frameworks, both give similar 3-D supramolecular architectures interpenetrated by 2-D layer frameworks. 3 forms a 1-D double-zigzag framework, and significantly the interlocking of the 1-D frameworks into the 28-membered rings of the adjacent chains generates a novel 1-D (1-D → 1-D) polyrotaxane framework. However, as the structural and isomeric analogue, 4 only forms a 1-D double-zigzag framework leading to a 2-D supramolecular structure by π π interactions and C-H N hydrogen bonding. 5 , composed of polymeric (Cu 2 I 2 ) n cluster chains, forms a 3-D coordination framework and interpenetrates to give a 2-fold interpenetrated framework. It is noted that these coordination frameworks show various structural motifs depending on the reaction conditions and ligands' backbones. In addition, the low-energy emissions at 538-615 nm for 1-5 either at room temperature or at 77 K have been observed, which are most likely to originate from an iodo-to-copper charge-transfer transition, possibly modified by Cu( i ) Cu( i ) interactions. The interlocking of 1-D frameworks into the 28-membered rings of the adjacent chains generates a novel 1-D (1-D → 1-D) polyrotaxane framework of 3 .