Branched compounds and their use in sensors

1. A sensor comprising:

(i) a compound of formula (I):

[DENDRON 1 ] p -CORE-[[X] r [DENDRON] m ] n   (I)

wherein

n is an integer of from 1 to 10;

p is zero or an integer of from 1 to 9;

the sum of n and p is from 3 to 10;

CORE is a group providing at least (n+p) points of attachment, each point of attachment being bonded to one X, DENDRON or DENDRON 1 group, and wherein the bonds between CORE and at least three X, DENDRON or DENDRON 1 groups are not co-planar;

each r is independently zero or an integer of from 1 to 10;

each m is independently zero or 1, with the proviso that for every point of attachment, when r is zero then m is one, and when m is zero then r is greater than zero;

each [X] r group is the same or different, wherein:

when m is zero, then −[X] r is a terminal group, and each X, which is the same or different if r is greater than one, is a group selected from aryl, heteroaryl, vinylene, acetylene and iptycene groups and from planar metal complexes;

when m is 1, then -[X] r - is a linking group bonded to the CORE and terminating in a single bond to the first branching group of DENDRON, and each X, which is the same or different if r is greater than one, is a group selected from aryl, heteroaryl, vinylene, acetylene and iptycene groups and from planar metal complexes;

each DENDRON is the same or different and represents an at least partially conjugated dendritic molecular structure comprising at least one branching group and optionally at least one linking group, the branching groups being selected from aryl and heteroaryl groups and nitrogen atoms, and the linking groups being selected from aryl, heteroaryl, vinyl and acetylenyl groups, said branching groups being bonded to three or more groups, and said linking groups being bonded to two groups, said dendritic molecular structure terminating at its distal points in aryl and/or heteroaryl groups; and

each DENDRON 1 , where present, represents an at least partially dendritic molecular structure,

wherein the compound of formula (I) is present in the sensor in the form of a film consisting essentially of said compound; and

(ii) an excitation source and detector capable of measuring the electronic and/or optical properties of the compound of formula (I).

2. A sensor as claimed in claim 1 wherein n is from 4 to 8.

3. A sensor as claimed in claim 2 wherein n is 4.

4. A sensor as claimed in claim 1 wherein each m is the same.

5. A sensor as claimed in claim 1 wherein p is zero.

6. A sensor as claimed in claim 1 wherein r is an integer of from 2 to 5 and each X is the same or different and represents a monocyclic aryl or heteroaryl group.

7. A sensor as claimed in claim 1 wherein r is an integer of from 1 to 5 and each X is the same or different and represents a polycyclic aryl or heteroaryl group.

8. A sensor as claimed in claim 1 wherein each X is selected from phenyl, naphthyl, anthracenyl, fluorenyl, pyridine and thiophene, said groups being optionally linked by vinylene and/or acetylene groups, and said groups being joined in series and being unsubstituted or substituted by one or more groups selected from C 1-10 alkyl and C 1-10 alkoxy.

9. A sensor as claimed in claim 8 wherein -[X] r -comprises three aryl groups in series and selected from phenyl and fluorenyl, said phenyl and fluorenyl groups being unsubstituted or substituted by from one to three C 1-4 alkyl groups.

10. A sensor as claimed in claim 1 wherein at least one m is one, and wherein each DENDRON, which are the same or different if more than one is present, represents an at least partially conjugated dendritic molecular structure comprising at least one branching group and optionally at least one linking group, the branching groups being selected from aryl and heteroaryl groups, and the linking groups being selected from aryl, heteroaryl, vinyl and acetylenyl groups, said branching groups being bonded to three or more groups, and said linking groups being bonded to two groups, said dendritic molecular structure terminating at its distal points in aryl groups which are unsubstituted or substituted.

11. A sensor as claimed in claim 1 wherein the film is deposited onto a patterned substrate.

12. A sensor as claimed in claim 1 where the film of the compound of formula (I) or formula (II) is patterned by soft lithography.

13. A sensor as claimed in claim 1 wherein the film of the compound of formula (I) or formula (II) lases.

14. A sensor as claimed in claim 1 wherein the excitation source and detector are capable of measuring an optical property of the compound.

15. A sensor as claimed in claim 14 wherein the optical property is luminescence of the compound.

16. A sensor as claimed in claim 1 wherein the excitation source and detector are capable of measuring an electronic property of the compound.

17. A sensor as claimed in claim 16 wherein the sensor is a field effect transistor.

18. A method of detecting the presence of a target analyte in a test substance which method comprises:

(i) providing a film consisting essentially of a compound of formula (I) as defined in claim 1 and measuring the electronic and/or optical properties of said compound;

(ii) exposing said film to the test substance and measuring the electronic and/or optical properties of the compound following exposure to the test substance;

(iii) comparing the electronic and/or optical properties obtained in step (ii) with those obtained in step (i); and

(iv) determining that the target analyte is present if the electronic and/or optical properties obtained in step (ii) are different from those obtained in step (i).

19. A method as claimed in claim 18 wherein the target analyte is an explosive.

20. A sensor comprising:

(i) a compound of formula (II):

[DENDRON 1 ] p -[X][DENDRON] q   (II)

wherein:

q is an integer of from 1 to 10;

p is zero or an integer of from 1 to 9;

the sum of p and q is from 2 to 10;

r is zero or an integer of from 1 to 10;

-[X] r - is a linker group between the two or more DENDRON or DENDRON 1 groups and providing at least (p+q) points of attachment, each point of attachment being bonded to a DENDRON or DENDRON 1 group;

each X, which is the same or different if r is greater than one, represents a group selected from aryl, heteroaryl, vinylene and acetylene groups and from planar metal complexes;

each DENDRON is the same or different and represents an at least partially conjugated dendritic molecular structure comprising at least one branching group and optionally at least one linking group, the branching groups being selected from aryl and heteroaryl groups and nitrogen atoms, and the linking groups being selected from aryl, heteroaryl, vinyl and acetylenyl groups, said branching groups being bonded to three or more groups, and said linking groups being bonded to two groups, said dendritic molecular structure terminating at its distal points in aryl and/or heteroaryl groups; and

each DENDRON 1 , where present, represents an at least partially dendritic molecular structure;

wherein the compound of formula (II) is present in the sensor in the form of a film consisting essentially of said compound; and

(ii) an excitation source and detector capable measuring the electronic and/or optical properties of the compound of formula (II).

21. A sensor as claimed in claim 20 wherein q is from one to six.

22. A sensor as claimed in claim 20 wherein p is zero, one or two.

23. A sensor as claimed in claim 20 wherein each DENDRON, which is the same or different, represents an at least partially conjugated dendritic molecular structure comprising at least one branching group and optionally at least one linking group, the branching groups being selected from aryl and heteroaryl groups, and the linking groups being selected from aryl, heteroaryl, vinyl and acetylenyl groups, said branching groups being bonded to three or more groups, and said linking groups being bonded to two groups, said dendritic molecular structure terminating at its distal points in aryl groups which are unsubstituted or substituted.