Lc. Tabares et al., Cooperative guest inclusion by a zeolite analogue coordination polymer. Sorption behavior with gases and amine and group 1 metal salts, J AM CHEM S, 123(3), 2001, pp. 383-387
Reaction of CuX2 (X = NO3, Cl, (SO4)(1/2)) salts and Hpymo . HX (Hpymo = 2-
hydroxypyrimidine X = Cl, NO3) in aqueous amine solutions (amine = NH3, CH3
NH2) leads to formation of the poorly crystalline three-dimensional open-fr
amework coordination polymer [Cu(pyma-N1,N3)2](infinity) (1). Under the sam
e 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)}(infinity) (1 . AX with A = NH4, CH3NH
3, Li, K, Rb; X = ClO4, BF4, PF6) are obtained. The X-ray crystal structure
of 1 . NH4ClO4 reveals that the combination of square-planar Cu2+ ion with
120 degrees bond angles provided by Hpymo generates a three-dimensional po
rous [Cu(pymo-N 1,N3)(2)](infinity) framework with ammonium and perchlorate
ions and water molecules included in the pores. 1 possesses a rich host-gu
est chemistry. Indeed, N; sorption at 77 K by empty host 1 reveals its micr
oporous nature with a BET surface area of ca. 200 m(2) g(-1). Hydrated 1 lo
ses water upon heating and when exposed to moist air regenerates the origin
al hydrated material. Likewise, 1 . NH4ClO4 loses ammonia upon heating, giv
ing the corresponding activated acidic material 1 . HClO4 which upon exposu
re to gaseous ammonia regenerates 1 . NH4ClO4. In addition, 1 reversibly an
d selectively sorbs AClO(4) salts (A = NH4, Li, Na, K,'Kb) when exposed to
AClO(4) aqueous solutions giving highly crystalline 1 . AClO(4) clathrates.
Cl-, NO3-, SiF62-, and SO42- salts are, however, not taken up. Salt sorpti
on 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.