Process for preparing aluminum trisquinoline complex

1. A process for forming the facial isomer of an aluminum trisquinoline complex comprising heating a solid aluminum trisquinoline complex material at a temperature at least 50° C. below the melting point temperature of the solid for a time sufficient to convert the aluminum trisquinoline complex to at least 99 mol % of one polymorph of the facial-isomer that fluoresces with a maximum intensity below 510 nm.

2. A process according to claim 1 , wherein the solid is heated at a temperature less than 150° C. below the melting point temperature of the solid.

3. A process according to claim 1 , comprising heating the solid material at a temperature at least 60° C. below the melting point temperature of the solid.

4. A process according to claim 1 , comprising heating the solid material at a temperature at least 70° C. below the melting point temperature of the solid.

5. A process according to claim 1 , comprising heating the solid material at a temperature at least 80° C. below the melting point temperature of the solid.

6. A process according to claim 1 , wherein X-ray powder diffraction (XRPD) is used to monitor the conversion to the facial-isomer by periodically measuring the spectra of representative samples.

7. A process according to claim 1 , wherein the aluminum trisquinoline complex is tris(2-methyl-8-quinolinolato)aluminum(III).

8. A process according to claim 6 , wherein the polymorph formed is the δ-phase of facial-tris(2-methyl-8-quinolinolato)aluminum(III).

9. A process according to claim 6 , comprising heating tris(2-methyl-8-quinolinolato)aluminum(III) at a temperature below 370° C. to form greater than 99% of the δ-phase of facial-tris(2-methyl-8-quinolinolato)aluminum(III).

10. A process according to claim 6 , comprising heating tris(2-methyl-8-quinolinolato)aluminum(III) at a temperature below 360° C. to form greater than 99% of the δ-phase of facial-tris(2-methyl-8-quinolinolato)aluminum(III).

11. A process according to claim 6 , comprising heating tris(2-methyl-8-quinolinolato)aluminum(III) at a temperature below 350° C. to form greater than 99% of the δ-phase of facial-tris(2-methyl-8-quinolinolato)aluminum(III).

12. A process for forming the facial-isomer of an aluminum trisquinoline complex comprising heating the solid aluminum trisquinoline complex material at a temperature below 340° C. for a time sufficient to form the facial-isomer, wherein the facial-isomer formed fluoresces with a maximum intensity below 510 nm.

13. A process according to claim 12 , wherein the solid material is heated at a temperature above 300° C.

14. A process according to claim 12 wherein the solid material is heated for a time sufficient to convert the solid to at least 99% of the facial-isomer.

15. A process according to claim 12 , wherein the aluminum trisquinoline complex is tris(2-methyl-8-quinolinolato)aluminum(III).

16. A process according to claim 15 , wherein the tris(2-methyl-8-quinolinolato)aluminum(III) is converted to at least 99% of the facial-isomer.

17. A process according to claim 15 , wherein a mixture of the γ- and δ-phases of tris(2-methyl-8-quinolinolato)aluminum(III) are formed.

18. A process according to claim 15 , wherein at 99% of the δ-phases of facial-tris(2-methyl-8-quinolinolato)aluminum(III) is formed.

19. A process according to claim 15 , wherein tris(2-methyl-8-quinolinolato)aluminum(III) is heated for up to 48 hours.