Flexible chiral pyrazolate-based metal-organic framework containing saddle-type CuI4(pyrazolate)4 units

Abstract

The syntheses and crystal structures of [CuI2(phbpz)]·MeOH (lp-CFA-9, lp = large-pore) and [CuI2(phbpz)] (np-CFA-9, np = narrow-pore; H2-phbpz = 3,3′,5,5′-tetraphenyl-1H,1′H-4,4′-bipyrazole) are described. The copper(i)-containing metal-organic framework (termed Coordination Framework Augsburg University-9, lp-CFA-9) crystallizes in the trigonal crystal system, within the chiral space group P3221 (no. 154) and with the following unit cell parameters: a =18.2348(6), c = 16.3950(4) Å, and V = 4721.1(2) Å3. Lp-CFA-9 features a 3-D microporous framework structure of Cu4pz4 (pz = pyrazolate) SBUs with the D2d (= 42m) symmetry connected by single bonds creating one-dimensional channels expanding in the c-direction of the crystal lattice. The framework flexibility of CFA-9 has been demonstrated by single-crystal and powder X-ray analyses as well as by sorption measurements. CFA-9 exhibits weak binding of carbon monoxide on Cu(i) centers. The reactivity of CFA-9 towards oxidizing agents, such as H2O2, t-BuOOH and Br2 was also investigated. Additionally, CFA-9 shows luminescence upon exposure to UV radiation.