Enantiomerically enriched, polycrystalline molecular sieves
This disclosure describes enantiomerically enriched chiral molecular sieves and methods of making and using the same. In some embodiments, the molecular sieves are silicates or germanosilicates of STW topology.
1. An enantiomerically enriched powder comprising two enantiomers of a chiral crystalline microporous solid, the chiral crystalline microporous solid having an STW topology and comprising:
(a) an oxide of silicon; and optionally
(b) one or more oxides of aluminum, boron, cerium, gallium, germanium, hafnium, iron, tin, titanium, indium, vanadium, zirconium, or a combination thereof,
wherein
the enantiomerically enriched powder exhibits an enantiomeric excess of one enantiomer of the chiral crystalline microporous solid over the other enantiomer of the chiral crystalline microporous solid of at least 10%.
2. The enantiomerically enriched powder of claim 1 , wherein the crystalline microporous solid is a pure silicate, an aluminosilicate, a borosilicate, a germanosilicate, a titanosilicate, a germanoaluminosilicate, or a germanotitanosilicate.
3. The enantiomerically enriched powder of claim 1 , wherein the crystalline microporous solid further comprises a chiral Organic Structure Directing Agent (OSDA) occluded within pores of the crystalline microporous solid, as determined by Circular Dichroism Analysis, the chiral OSDA comprising a structure having a linked pair of imidazolium cations of a structure:
wherein Linker is a 3, 4, 5, or 6-membered ring chiral linking group or an alicyclic four-carbon chiral linking group; and
R is independently methyl or ethyl; and
n is independently 0, 1, 2, or 3.
4. The enantiomerically enriched powder of claim 3 , wherein Linker comprises a chirally substituted cyclopropane, aziridine, epoxide, cyclobutane, cyclopentane, cyclohexane, tetrahydrofuran, pyrrolidine, or tetrahydrothiophene.
5. The enantiomerically enriched powder of claim 3 , wherein Linker comprises a structure:
where R 1 is H or C 1-6 alkyl, R 2 and R 3 are independently C 1-12 alkyl or aryl.
6. The enantiomerically enriched powder of claim 3 , wherein Linker comprises a structure:
where R 1 is H or C 1-6 alkyl, R 2 and R 3 are independently C 1-12 alkyl or aryl.
7. The enantiomerically enriched powder of claim 1 , wherein the crystalline microporous solid is substantially free of occluded organic material, the crystalline microporous solid being predominantly in a hydrogen form.
8. The enantiomerically enriched powder of claim 1 , wherein the crystalline microporous solid is calcined and contains a transition metal or transition metal oxide within its pores.
9. The enantiomerically enriched powder of claim 1 , wherein the crystalline microporous solid is calcined and contains Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Be, Al, Ga, In, Zn, Ag, Cu, Fe, Co, Ni, Cd, Ru, Rh, Pd, Pt, Au, Hg, La, Ce, Pr, Nd, Pm, Sm, Eu, or R 4-n N + H n cations, where R is alkyl, n=0-4, in its pores.
10. A process for preparing the enantiomerically enriched powder of claim 1 , the process comprising hydrothermally treating a composition comprising:
(a) at least one source of a silicon oxide;
(b) optionally at least one source of aluminum oxide, boron oxide, cerium oxide, gallium oxide, germanium oxide, hafnium oxide, iron oxide, tin oxide, titanium oxide, vanadium oxide, zinc oxide, zirconium oxide, or a combination or mixture thereof;
(c) either a source of fluoride or a source of hydroxide; and
(d) a linked pair of quaternary imidazolium cations of a structure:
wherein
Linker is a 3, 4, 5, or 6-membered ring chiral linking group or an alicyclic four-carbon chiral linking group; and
R is independently methyl or ethyl; and
n is independently 0, 1, 2, or 3;
under conditions effective to crystallize a crystalline microporous solid that exhibits a chiral morphology and to form the enantiomerically enriched powder of claim 1 .
11. The process of claim 10 , wherein the conditions are conducive to forming a crystalline microporous silicate composition having STW topology.
12. The process of claim 10 , wherein the hydrothermally treating is done at a temperature in a range of from about 100° C. to about 200° C. for a time effective for crystallizing the crystalline microporous solid.
13. The process of claim 10 , further comprising isolating the crystalline microporous solid.
14. The process of claim 13 , further comprising calcining the isolated crystalline microporous solid at a temperature in a range of from about 350° C. to about 850° C.
15. The process of claim 14 , further comprising treating the calcined material with an aqueous ammonium salt.
16. The process of claim 15 , further comprising treating the calcined crystalline microporous solid with at least one alkali metal cation, alkaline earth metal cation, transition metal, or transition metal oxide.
17. The enantiomerically enriched powder of claim 3 , wherein R is methyl.
18. The enantiomerically enriched powder of claim 3 , wherein n is 2 or 3.
19. The process of claim 10 , wherein R is methyl.
20. The process of claim 10 , wherein n is 2 or 3.
21. The enantiomerically enriched powder of claim 3 , wherein Linker comprises a 4, 5, or 6-membered saturated cyclic chiral linking group.
22. The process of claim 10 , wherein Linker comprises a 4, 5, or 6-membered saturated cyclic chiral linking group.
23. The enantiomerically enriched powder of claim 1 that exhibits an enantiomeric excess of an R-STW enantiomer of at least 50%.
24. The enantiomerically enriched powder of claim 1 that exhibits an enantiomeric excess of an R-STW enantiomer of at least 75%.
25. The enantiomerically enriched powder of claim 1 that exhibits an enantiomeric excess of an R-STW enantiomer of about 100%.
26. The enantiomerically enriched powder of claim 1 that exhibits an enantiomeric excess of an S-STW enantiomer of at least 50%.
27. The enantiomerically enriched powder of claim 1 that exhibits an enantiomeric excess of an S-STW enantiomer of at least 75%.
28. The enantiomerically enriched powder of claim 1 that exhibits an enantiomeric excess of an S-STW enantiomer of about 100%.