P -Xylylenediamine derived ligands as flexible connectors in the design of porous coordination polymers

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Abstract

The use of flexible ligands in coordination polymers provides both opportunities and unpredictability. A new series of flexible ligands derived from p-xylylenediamine, which vary in the positioning of carboxylic acid functional groups, have been found to form a series of coordination polymers and a discrete coordination complex. Use of the tetra-substituted meta-carboxylic acid ligand N,N,N′,N′-tetra(3-carboxybenzyl)-p-xylylenediamine, isolated as its dihydrochloride salt (H 6 M 4 pxy)Cl 2 , resulted in the simultaneous formation of two products from the same synthetic conditions. One of these products was a discrete cage-type coordination complex of the form [Cu 4 (M 4 pxy) 2 (DMF) 2 (OH 2 )] (1), while the other product was the two-dimensional coordination polymer poly-[Cu 2 (M 4 pxy)(OH 2 ) 2 ] (2). Synthesis utilising the tetra-substituted para-carboxylic acid ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-p-xylylenediamine dihydrochloride (H 6 P 4 pxy)Cl 2 , resulted in the formation of multiple two-dimensional coordination polymers, poly-[Cu 2 (P 4 pxy)(DMF)(OH 2 )]·2DMF·3H 2 O (3·2DMF·3H 2 O), poly-[Mn 2 (P 4 pxy)(DMA) 2 ] (4), poly-[Co 4 (P 4 pxy) 2 (DMF) 2 (μ-OH 2 ) 2 (OH 2 ) 2 ]·6DMF·4H 2 O (5·6DMF·4H 2 O) and poly-[Cd 2 (P 4 pxy)(OH 2 ) 2 ]·DMA·3H 2 O (6·DMA·3H 2 O). The last of these materials, a three-dimensional coordination polymer, was found to adsorb approximately 32 cm 3 g -1 STP of CO 2 at atmospheric pressure at 273 K.

Original languageEnglish
Pages (from-to)3074-3085
Number of pages12
JournalCrystEngComm
Volume21
Issue number19
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • Chelation
  • Ligands
  • Atmospheric pressure
  • Carboxylic acids

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