Electroluminescent devices

1. A compound of formula [I]:

X—R  [I]

wherein X represents the group:

and R is either (i) represented by the formula [II]

wherein n is 1 or 2, and the or each R 7 group is independently selected from the group consisting of hydrogen and halogen atoms, cyano, nitro, mercapto, carbonyl and sulfone groups, and optionally substituted alkyl, haloalkyl, hydroxyalkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylthio, arylthio, ester, siloxy, cyclic hydrocarbon and heterocyclic groups;

or (ii) is selected from the group consisting of optionally substituted alkyl, hydroxyalkyl, aryl, cyclic hydrocarbon and heterocyclic groups;

wherein in each case R 1 –R 6 are each independently selected from the group consisting of hydrogen and halogen atoms, cyano, nitro, mercapto, carbonyl and sulfone groups, and optionally substituted alkyl, haloalkyl, hydroxyalkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylthio, arylthio, ester, siloxy, cyclic hydrocarbon and heterocyclic groups; except when R is aryl, then one of R 5 and R 6 is other than hydrogen; and except when R is methyl, then one of R 5 and R 6 is other than fluorine, other than phenoxy, and other than hydrogen; and except when R is phenyl, then one of R 5 and R 6 is other than chlorine; and except when R is tolyl, then one of R 5 and R 6 is other than phenoxy, and other than fluorine; and when R is tolyl, then one of R 5 and R 6 is other than fluorine and the other of R 5 and R 6 is other than arylamino.

2. The compound of claim 1 wherein R is selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

3. The compound of claim 1 having formula [IV]:

4. The compound of claim 3 wherein the or each R 7 group is independently selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

5. The compound of claim 1 having the formula [V]:

6. The compound of claim 5 wherein the or each R 7 group is independently selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

7. The compound of claim 1 wherein R 1 –R 6 are selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

8. The compound of claim 1 wherein R 1 –R 6 are hydrogen atoms when R is other than aryl and other than methyl.

9. An organic electroluminescence device comprising

an anode;

a cathode;

a hole transporting layer; and

an electron transporting layer;

wherein the hole-transporting layer is disposed between the anode and the electron-transporting layer and the electron-transporting layer is disposed between the cathode and the hole-transporting layer, and the hole-transporting layer comprises a compound of formula [I]

X—R  [I]

wherein X represents the group:

and R is either (i) represented by the formula [II]

wherein n is 1 or 2, and the or each R 7 group is independently selected from the group consisting of hydrogen and halogen atoms, cyano, nitro, mercapto, carbonyl and sulfone groups, and optionally substituted alkyl, haloalkyl, hydroxyalkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylthio, arylthio, ester, siloxy, cyclic hydrocarbon and heterocyclic groups;

or (ii) is selected from the group consisting of optionally substituted alkyl, hydroxyalkyl, aryl, cyclic hydrocarbon and heterocyclic groups;

wherein in each case R 1 –R 6 are each independently selected from the group consisting of hydrogen and halogen atoms, cyano, nitro, mercapto, carbonyl and sulfone groups, and optionally substituted alkyl, haloalkyl, hydroxyalkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylthio, arylthio, ester, siloxy, cyclic hydrocarbon and heterocyclic groups; except when R is aryl, then one of R 5 and R 6 is other than hydrogen: and except when R is methyl, then one of R 5 and R 6 is other than fluorine, other than phenoxy, and other than hydrogen; and except when R is phenyl, then one of R 5 and R 6 is other than chlorine; and except when R is tolyl, then one of R 5 and R 6 is other than phenoxy, and other than fluorine; and when R is tolyl, then one of R 5 and R 6 is other than fluorine and the other of R 5 and R 6 is other than arylamino.

10. An organic electroluminescence device according to claim 9 wherein R is selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

11. An organic electroluminescence device according to claim 9 wherein the hole transporting layer comprises a compound of formula [IV]:

12. An organic electroluminescence device according to claim 9 wherein the or each R 7 group is independently selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

13. An organic electroluminescence device according to claim 9 wherein the hole-transporting layer comprises a compound of formula [V]:

14. An organic electroluminescence device according to claim 9 wherein the or each R 7 group is independently selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

15. An organic electroluminescence device according to claim 9 wherein R 1 –R 6 are selected from the group consisting of alkyl, haloalkyl, aryl and heterocyclic groups.

16. An organic electroluminescence device according to claim 9 wherein R 1 –R 6 are hydrogen atoms when R is other than aryl and other than methyl.

17. An organic electroluminescence device according to claim 9 wherein a luminescent material is incorporated in the electron transporting layer.

18. An organic electroluminescence device according to claim 9 wherein a luminescent material is incorporated in the hole transporting layer.

19. An organic electroluminescence device according to claim 9 wherein a luminescent layer is disposed between the electron transporting layer and the hole transporting layer.

20. An organic electroluminescence device according to claim 9 wherein the hole transporting layer comprises an additional hole transporting compound selected from the group consisting of optionally substituted phthalocyanine derivatives, napththalocyanine derivatives, porphyrin derivatives, pyrazoline derivatives, carbazole derivatives, thiophene derivatives, aromatic tertiary amine derivatives, benzidine derivatives, triphenylamine derivatives, polyvinylcarbazole and polysilane.

21. An organic electroluminescence device according to claim 20 wherein the additional hole transporting compound has a structure selected from the group consisting of:

22. An organic electroluminescence device according to claim 9 additionally comprising a hole injection material disposed between the anode and the hole transporting layer.

23. A method of using a compound of formula [I]in an electroluminescence device:

X—R  [I]

wherein X represents the group:

and R is either (i) represented by the formula [II]

wherein n is 1 or 2, and the or each R 7 group is independently selected from the group consisting of hydrogen and halogen atoms, cyano, nitro, mercapto, carbonyl and sulfone groups, and optionally substituted alkyl, haloalkyl, hydroxyalkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylthio, arylthio, ester, siloxy, cyclic hydrocarbon and heterocyclic groups;

or (ii) is selected from the group consisting of optionally substituted alkyl, hydroxyalkyl, aryl, cyclic hydrocarbon and heterocyclic groups;

wherein in each case R 1 –R 6 are each independently selected from the group consisting of hydrogen and halogen atoms, cyano, nitro, mercapto, carbonyl and sulfone groups, and optionally substituted alkyl, haloalkyl, hydroxyalkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylthio, arylthio, ester, siloxy, cyclic hydrocarbon and heterocyclic groups; except when R is aryl, then one of R 5 and R 6 is other than hydrogen; the method comprising providing a compound of formula [I], and incorporating said compound as a hole-transporting material within an electroluminescence device which further comprises an anode, a cathode and an electron-transporting material.