Fluorite and mixed-metal Kagome-related topologies in metal-organic framework compounds: synthesis, structure, and properties.
Two new three-dimensional metal-organic frameworks (MOFs) [Mn(2)(mu(3)-OH)(H(2)O)(2)(BTC)] x 2 H(2)O, I, and [NaMn(BTC)], II (BTC = 1,2,4-benzenetricarboxylate = trimellitate) were synthesized and their structures determined by single-crystal X-ray diffraction (XRD). In I, the Mn(4) cluster, [Mn(4)(mu(3)-OH)(2)(H(2)O)(4)O(12)], is connected with eight trimellitate anions and each trimellitate anion connects to four different Mn(4) clusters, resulting in a fluorite-like structure. In II, the Mn(2)O(8) dimer is connected with two Na(+) ions through carboxylate oxygen to form mixed-metal distorted Kagome-related two-dimensional -M-O-M- layers, which are pillared by the trimellitate anions forming the three-dimensional structure. The extra-framework water molecules in I are reversibly adsorbed and are also corroborated by powder XRD studies. The formation of octameric water clusters involving free and coordinated water molecules appears to be new. Interesting magnetic behavior has been observed for both compounds. Electron spin resonance (ESR) studies indicate a broadening of the signal below the ordering temperature and appear to support the findings of the magnetic studies.
Mahata
Partha
P
Framework Solids Laboratory, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India), Fax: (+91) 80-2360-1310.
Raghunathan
Rajamani
R
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India).
Banerjee
Debamalya
D
Department of Physics, Indian Institute of Science, Bangalore 560012 (India).
Sen
Diptiman
D
Centre for High Energy Physics, Indian Institute of Science, Bangalore 560 012 (India).
Ramasesha
S
S
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India).
Bhat
S V
SV
Department of Physics, Indian Institute of Science, Bangalore 560012 (India).
Natarajan
S
S
Framework Solids Laboratory, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India), Fax: (+91) 80-2360-1310.