Cooperative Guest Inclusion by a Zeolite Analogue Coordination Polymer. Sorption Behavior with Gases and Amine and Group 1 Metal Salts

Reaction of CuX 2 (X = NO 3, Cl, (SO 4 ) 1/2 ) salts and Hpymo·HX (Hpymo = 2-hydroxypyrimidine; X = Cl, NO 3 ) in aqueous amine solutions (amine = NH 3, CH 3 NH 2 ) leads to formation of the poorly crystalline three-dimensional open-framework coordination polymer [Cu(pymo-N1,N3) 2 ] ∞ ( 1 ). Under the same reaction conditions, but in the presence of amine and group 1 metal salts of single charged voluminous anions, highly crystalline clathrates of the type {[Cu(pymo-N1,N3) 2 ] · (AX) 1/3 } ∞ ( 1·AX with A = NH 4, CH 3 NH 3, Li, K, Rb; X = ClO 4, BF 4, PF 6 ) are obtained. The X-ray crystal structure of 1·NH 4 ClO 4 reveals that the combination of square-planar Cu 2+ ion with 120° bond angles provided by Hpymo generates a three-dimensional porous [Cu(pymo-N1,N3) 2 ] ∞ framework with ammonium and perchlorate ions and water molecules included in the pores. 1 possesses a rich host−guest chemistry. Indeed, N 2 sorption at 77 K by empty host 1 reveals its microporous nature with a BET surface area of ca. 200 m 2 g - 1 . Hydrated 1 loses water upon heating and when exposed to moist air regenerates the original hydrated material. Likewise, 1·NH 4 ClO 4 loses ammonia upon heating, giving the corresponding activated acidic material 1·HClO 4 which upon exposure to gaseous ammonia regenerates 1·NH 4 ClO 4 . In addition, 1 reversibly and selectively sorbs AClO 4 salts (A = NH 4, Li, Na, K, Rb) when exposed to AClO 4 aqueous solutions giving highly crystalline 1·AClO 4 clathrates. Cl -, NO 3 -, SiF 6 2 -, and SO 4 2 - salts are, however, not taken up. Salt sorption curves are of type V and possess hysteresis loops. This behavior agrees with the observed guest-induced structure phase change taking place in the 1 framework after guest inclusion.