Three helical chain-based 3D coordination polymers: solvent-induced syntheses, tunable structures and catalytic properties for the Strecker reaction

• Published in: CrystEngComm Vol. 21; no. 36; pp. 544 - 5447
• Main Authors: Chai, Juan, Zhang, Ping, Shi, Xiangxiang, Sun, Jing, Wang, Li, Fan, Yong
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Catalysis; Catalytic activity; Chains (polymeric); Coordination polymers; Crystallography; Dichroism; Handedness; Ligands; Optical activity; Polarity; Solvents; Synthesis
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/c9ce00972h

Three three-dimensional (3D) helical chain-based coordination polymers [Sc(aip)(OH)·(H 2 O)] n ( 1 ), [Sc 2 (aip) 3 ] n ( 2 ) and [Sc 2 (nip) 3 ] n ( 3 ) (H 2 aip = 5-aminoisophthalic acid, H 2 nip = 5-nitroisophthalic acid) have been synthesized through solvent induction without any chiral auxiliary systematically. We first synthesized CP 1 , a 3D network, which contains intertwined left- and right-hand helical chains {-ScO 6 -OH-} n . By changing the polarity of the solvents from CH 3 CN/H 2 O to H 2 O, a genuine single helix of 2 was constructed, in which adjacent Sc(COO) 6 polyhedra are connected alternately by aip 2− ligands to form a 3D framework with intertwined parallel left-hand helical chains {-Sc1(COO)-Sc2(COO)-} n . Then by changing the substituent of the ligand, CP 3 was obtained with right-handed helical chains. As for 3 , the aip 2− ligands bridge Sc( iii ) ions alternately into infinite right-handed helical chains {-Sc(COO)-} n , which serve as secondary building units (SBU) to generate a 3D framework. Solid-state circular dichroism spectrum confirms that 3 is optically active. We also studied the catalytic properties of 1-3 in the Strecker reaction. Importantly, 1 shows excellent catalytic activity under mild conditions and can be reused at least four times without significant reduction in catalytic ability. Three 3D Sc-CPs with different helical chains have been synthesized from isophthalic acid derivatives by solvent induced methods. Among them, 3 is optically active. Furthermore, 1 exhibits good catalytic activity for the Strecker reactions.