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Structural Flexibility and Selective Guest Accommodation in Two Cu II Metal–Organic Coordination Frameworks
Author(s) -
Gurunatha Kargal L.,
Maji Tapas Kumar
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200801153
Subject(s) - chemistry , crystallography , supramolecular chemistry , molecule , stacking , metal organic framework , sbus , triclinic crystal system , ligand (biochemistry) , sorption , pyridine , crystal structure , crystal engineering , aqueous solution , inorganic chemistry , adsorption , medicinal chemistry , organic chemistry , biochemistry , receptor
Two metal–organic coordination frameworks of Cu II , [Na 2 Cu(2,4‐pyrdc)(H 2 O)(μ‐OH 2 ) 2 ] n ( 1 ) and {[Cu(2,5‐pyrdc) (NH 3 )](2H 2 O)} n ( 2 ) (2,4‐pyrdc = pyridine‐2,4‐dicarboxylate; 2,5‐pyrdc = pyridine‐2,5‐dicarboxylate), were synthesized and structurally characterized. The structure of compound 1 was known and shows that Cu(2,4‐pyrdc) 2 (H 2 O) functions as a metalloligand and is linked to two different Na I atoms to form a 3D heterometallic Cu II –Na I framework. The single crystals of compound 2 were obtained from aqueous ammoniacal solution and crystallize in the triclinic ( P $\bar {1}$ ) crystal system. Compound 2 is a 2D sheet consisting of two different Cu II 1D chains bridged by a 2,5‐pyrdc ligand. Stacking of the 2D sheets results in a 3D supramolecular host with 1D water‐filled channels. Both frameworks are highly thermally stable and exhibit reversible structural transformation upon removal of the metal‐bound water and NH 3 molecules for 1 and 2 , respectively. Sorption studies reveal that desolvated frameworks 1′ and 2′ both behave nonporous to N 2 . However, 1′ exhibits structural transformation and hysteretic stepwise sorption of H 2 O and MeOH molecules, but THF and C 6 H 6 molecules are not adsorbed. Similarly, H 2 O and MeOH molecules are easily adsorbed in 2′ , but THF and C 6 H 6 molecules are not. Such high selectivity in 1′ and 2′ was correlated to the smaller pore aperture and specific host–guest interaction conferred by the unsaturated Lewis acidic sites on the pore surfaces and the Lewis basic adsorbates. Low‐temperature magnetic study of 2 revealed that theCu II atoms are antiferromagnetically coupled, with J = –1.45 cm –1 and g = 2.01.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)