Abstract
In this research, six novel bimetal phosphites were synthesized under hydrothermal conditions. These compounds are divided into systems A and B according to different types of organic template (straight carbon chain monoamine or bolaamphiphilic-type diamine). The contents include rational design synthesis of inorganic structures with extra-large pores, detailed discussion and comparison on the structure symmetry and building blocks arrangement, and different template effects between mono- and diamine templates. The chemical formula of six compounds are listed: (Hha)4[GaFZn7(H2O)4(HPO3)10] (A1)、(Hha)6[Ga2F2Zn9(H2O)4(HPO3)14]‧0.1TMB (A2)、(Hoda)10[Ga2F2Zn19(H2O)12(HPO3)26]‧TMB (A3)、(H2DAD)[GaFZn2(HPO3)4] (B1)、(H2DADD)2[GaFZn7(H2O)4(HPO3)10]‧4H2O (B2)、(H2DADD)3[Ga2FZn5(OH)5(HPO3)8]‧9H2O (B3) ha = 1-hexylamine, oda = 1-octadecylamine, DAD = 1,10-diaminodecane, DADD = 1,12-diaminododecane, TMB = 1,3,5-trimethybenzene. Among six compounds, A1, A2, and A3 possess 28R, 40R, and 72R channels, respectively; B1 possess 24R channels; B2 is isostructural with A1; B3 is a layer structure. Their structures are highly related and can be described by five building blocks: [GaF(HPO3)2]2- (block A)、∞[Zn(HPO3)] (block B)、[Zn(HPO3)2(H2O)4]2- (block C)、∞[Ga2FZn(OH)5(HPO3)4]6- (block α)與∞[Zn(HPO3)] (block β). The repeating blocks of these compounds are [A(BC)β(CB)A] (A1 and B2)、[A(BC)BA] (A2)、[A(BC)3BA] (A3)、[ABA] (B1) and [αBα] (B3). In system A, straight carbon chain monoamines were used for rational synthesis of crystalline structures with extra-large pores. The lengths of straight carbon chains were extended from four carbons (4C') to 18C', giving pore sizes expanding from 24R, 28R (A1), 40R(A2), 48R, 56R, 64R to 72R (A3). A3 is a crystalline mesoporous structure with pore diameter reaching 3.5 nm, and the ring-size up to 72R has become a new world record. Besides, TMB was found to be an efficient porogen in this system. By adding both 6C' and TMB into reaction, 28R structure (A1) was expanded to 40R (A2) structure. Moreover, by adding both 18C' and TMB into reaction, 64R structure was expanded to 72R (A3) structure. In system B, bolaamphiphilic-type diamines were used for the reproduction of 24R (B1) and 28R (B2) structures, and for the synthesis of a new layer structure B3. The 24R structures templated by mono- or diamine are both tetragonal, while diamine templated B2 was crystallized in a lower symmetry (orthorhombic) compared to A1 (tetragonal). The reason can be attributed to the block β (particularly involved in B2 and A1) which can be assumed to be a soft part and might slightly twist when templated by diamine. The puckered layer structure B3 possesses a unique block α, which was observed to reside in the nearest and farthest positions between two layers. The comparison between repeating blocks of B1 and B3 revealed that the replacement of A by α could degrade the 24R structure to a layer structure. This research has deeply discussed the relationships between straight carbon chain monoamines/diamines and inorganic building blocks in a rational design system, and has also firstly revealed the template effects from micro- to mesoporous regime.