Segmented graphene nanoribbons

Abstract

The present invention relates to a segmented graphene nanoribbon, comprising at least two different graphene segments covalently linked to each other, each graphene segment having a monodisperse segment width, wherein the segment width of at least one of said graphene segments is 4 nm or less and to a method for preparing it by polymerizing at least one polycyclic aromatic monomer compound and/or at least one oligo phenylene aromatic hydrocarbon monomer compound to form at least one polymer and by at least partially cyclodehydrogenating the one or more polymer.

Claims

1. A process for preparing the segmented graphene nanoribbon comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein said process comprises: (a) depositing at least one polycyclic aromatic monomer compound and/or oligo phenylene aromatic hydrocarbon monomer compound on a solid substrate; (b) polymerizing the polycyclic aromatic and/or oligo phenylene aromatic hydrocarbon monomer compound so as to form at least one polymeron the surface of the solid substrate; and (c) at least partially cyclodehydrogenating the one or more polymers of (b).

2. The process of claim 1, wherein each graphene segment of the segmented graphene nanoribbon has a monodisperse segment width of 4 nm or less.

3. The process of claim 1, wherein each graphene segment has a repeating unit derived from at least one substituted or unsubstituted polycyclic aromatic monomer compound, and/or from at least one substituted or unsubstituted oligo phenylene aromatic hydrocarbon monomer compound.

4. The process of claim 3, wherein the repeating units of different graphene segments differ in at least in one property selected from the group consisting of segment width, substituents attached to the repeating unit, degree of annelation of aromatic rings, degree of cyclodehydrogenation, and number of annelated aromatic rings.

5. The process of claim 1, wherein each of the segments of the segmented graphene nanoribbon has a length in the range of 0.25 to 250 nm, and/or the total length of the segmented graphene nanoribbon is at least 4 nm.

6. The process of claim 1, wherein the segments of the segmented graphene nanoribbon are in a linear arrangement, or at least one segment of the segmented graphene nanoribbon is covalently linked to at least three neighbouring segments.

7. The process of claim 1, wherein at least one of the graphene segments has a substituted or unsubstituted repeating unit with Ni dimer lines across the segment width, and at least one of the graphene segments has a substituted or unsubstituted repeating unit with N2 dimer lines across the segment width, wherein N1=5 to 13, and N2=kN1, with k=2, 3, or 4.

8. The process of claim 1, wherein the two or more different graphene segments have repeating units which are derived from substituted or unsubstituted anthracene monomer compounds.

9. The process of claim 8, wherein the segmented graphene nanoribbon has the structure Ia: ##STR00032## under the provision that at least two of m, x, n, y, o, z, and p are 1; and m+x+n+y+o+z+p10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy; C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00033## and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

10. The process of claim 1, wherein two or more different graphene segments have repeating units which are derived from substituted or unsubstituted pentacene monomer compounds.

11. The process of claim 10, wherein the segmented graphene nanoribbon has the structure II: ##STR00034## under the provision that at least two of m, x, n, y, o, z, and p are 1; wherein m+x+n+y+o+z+p10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy; C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00035## and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

12. The process of claim 1, wherein two or more different graphene segments have repeating units which are derived from substituted or unsubstituted anthracene and pentacene monomer compounds.

13. The process of claim 12, wherein the segmented graphene nanoribbon has the structure IV: ##STR00036## wherein m+n10, and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy: C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00037## wherein R1 is a different structure than R2; and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

14. The process of claim 1, wherein two or more different graphene segments have repeating units derived from substituted and/or unsubstituted naphthalene monomer compounds.

15. The process of claim 14 wherein the segmented graphene nanoribbon has the structure V: ##STR00038## under the provision that at least two of m, x, and n are 1; wherein m+x+n are 10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy: C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00039## and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

16. The process of claim 1, wherein at least one of the segments has a substituted or unsubstituted repeating unit with N1=5 and at least one of the segments has a substituted or unsubstituted repeating unit with N2=10 or 15, wherein N1 and N2 are the number of dimer lines across the segment width.

17. The process of claim 16 wherein the segmented graphene nanoribbon has the structure XI: ##STR00040## under the proviso that at least one m, p, q, r, s, u, v, w, and x is 1, and at least one of n, o, and t is 1; wherein m+n+o+p+q+r+s+t+u+v+w+x10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units.

18. The process of claim 1, wherein at least one of the segments has a substituted or unsubstituted repeating unit with N1=7 and at least one of the segments has a substituted or unsubstituted repeating unit with N2=14 or 21, wherein N1 and N2 are the number of dimer lines across the segment width.

19. The process of claim 18 wherein the segmented graphene nanoribbon has the structure If: ##STR00041## under the proviso that at least one m, p, q, w, x, r, s, and v are 1, and at least one of n, o, and t are 1; wherein m+n+o+p+q+r+s+t+u+v+w+x10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units.

20. The process of claim 1, comprising at least one heterojunction.

21. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein the two or more different graphene segments have repeating units which are derived from substituted or unsubstituted anthracene monomer compounds and wherein the segmented graphene nanoribbon has the structure Ia: ##STR00042## under the provision that at least two of m, x, n, y, o, z, and p are 1; and m+x+n+y+o+z+p10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy: C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00043## and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

22. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein two or more different graphene segments have repeating units which are derived from substituted or unsubstituted pentacene monomer compounds and wherein the segmented graphene nanoribbon has the structure II: ##STR00044## under the provision that at least two of m, x, n, y, o, z, and p are 1; wherein m+x+n+y+o+z+p10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy: C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00045## and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

23. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein two or more different graphene segments have repeating units which are derived from substituted or unsubstituted anthracene and pentacene monomer compounds and wherein the segmented graphene nanoribbon has the structure IV: ##STR00046## wherein m+n0, and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy: C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00047## wherein R1 is a different structure than R2; and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

24. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein two or more different graphene segments have repeating units derived from substituted and/or unsubstituted naphthalene monomer compounds and wherein the segmented graphene nanoribbon has the structure V: ##STR00048## under the provision that at least two of m, x, and n are 1; wherein m+x+n are 10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units; R are each independently hydrogen; linear or branched or cyclic C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more OH, C.sub.1-C.sub.4alkoxy, phenyl, or by CN; C.sub.2-C.sub.12alkyl which is interrupted by one or more non-consecutive O; halogen; OH; OR.sub.3; SR.sub.3; CN; NO.sub.2; NR.sub.1R.sub.2; (CO)R.sub.3; (CO)OR.sub.3; O(CO)OR.sub.3; O(CO)NR.sub.1R.sub.2; O(CO)R.sub.3; C.sub.1-C.sub.12alkoxy: C.sub.1-C.sub.12alkylthio; (C.sub.1-C.sub.6alkyl)-NR.sub.7R.sub.8; or O(C.sub.1-C.sub.6alkyl)NR.sub.1R.sub.2; aryl or heteroaryl (wherein aryl is preferably phenyl, biphenyl, naphthyl, or anthryl all of which are unsubstituted or are substituted by one or more C.sub.1-C.sub.4-alkyl, CN, OR.sub.3, SR.sub.3, CH.sub.2OR.sub.3, (CO)OR.sub.3, (CO)NR.sub.1R.sub.2 or halogen); or two R together with the carbon atoms they are attached to form a 5-8-membered cycle or heterocycle; R.sub.1 and R.sub.2 are each independently hydrogen, linear or branched C.sub.1-C.sub.6alkyl or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded to form a group selected from ##STR00049## and R.sub.3 is H, C.sub.1-C.sub.12alkyl, phenyl which is unsubstituted or is substituted by one or more C.sub.1-C.sub.4alkyl, phenyl, halogen, C.sub.1-C.sub.4alkoxy or C.sub.1-C.sub.4alkylthio.

25. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein at least one of the segments has a substituted or unsubstituted repeating unit with N1=5 and at least one of the segments has a substituted or unsubstituted repeating unit with N2=10 or 15, wherein Ni and N2 are the number of dimer lines across the segment width and wherein the segmented graphene nanoribbon has the structure XI: ##STR00050## under the proviso that at least one m, p, q, r, s, u, v, w, and x is 1, and at least one of n, o, and t is 1; wherein m+n+o+p+q+r+s+t+u+v+w+x10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units.

26. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, wherein at least one of the segments has a substituted or unsubstituted repeating unit with N1=7 and at least one of the segments has a substituted or unsubstituted repeating unit with N2=14 or 21, wherein N1 and N2 are the number of dimer lines across the segment width and wherein the segmented graphene nanoribbon has the structure If: ##STR00051## under the proviso that at least one of m, p, q, w, x, r, s, u, and v are 1, and at least one of n, o, and t are 1; wherein m+n+o+p+q+r+s+t+u+v+w+x10; and wherein X are each independently H, a halogen, SH, SR.sub.3, OH, OR.sub.3, OSO.sub.2R.sub.3, (SO)R.sub.3, (SO.sub.2)R.sub.3, NR.sub.1R.sub.2, NO.sub.2, POR.sub.3R.sub.3, PO(OR.sub.3)R.sub.3, PO(OR.sub.3).sub.2, B(R.sub.3).sub.2, B(OR.sub.3).sub.2, (CO)R.sub.3, (CO)OR.sub.3; Y are each independently H or two Y together form a direct bond between neighbouring repeating units.

27. A segmented graphene nanoribbon, comprising: at least two different graphene segments covalently linked to each other; wherein each graphene segment has a monodisperse segment width; wherein the segment width of at least one of the graphene segments is 4 nm or less, and comprising at least one heterojunction.

Description

EXAMPLES

1. Experimental Details

(1) The molecular precursor 10,10-dibromo-9,9-bianthryl was sublimated at a rate of 1 /min for 100 seconds onto a clean Au(111) single crystal substrate which was cleaned by repeated cycles of argon ion bombardment and annealing to 750 K. The substrate was maintained at room temperature during deposition and then immediately annealed to 480 K to induce dehalogenation and radical addition. Then the sample was post-annealed at 600 K for 5 min to partially cyclodehydrogenate the polymers.

Example 1: Preparation of Segmented Graphene Nanoribbons from the Molecular Precursor 10,10-dibromo-9,9-bianthryl by Thermally Activated Cyclodehydrogenation

(2) The key step of the bottom-up GNR fabrication method is the surface-assisted thermally induced cyclodehydrogenation of linear polyphenylenes on Au or Ag templates. The method, which does not need a Lewis acid or other catalyst than the supporting metal substrate, is highly selective and efficient. Scanning tunneling microscopy (STM) experiments demonstrate that polyanthrylene chains adsorbed on Au or Ag substrates undergo cyclodehydrogenation upon annealing at 670 K: The ends of the anthryl units alternately pointing up and down couple with each other and transform the buckled polymer chain into a fully planar 7-AGNR (graphene nanoribbon with armchair configuration and 7 dimer lines across the segment width).

(3) FIGS. 1a and 1b illustrates the realization of graphene nanoribbon heterojunctions by partial cyclodehydrogenation of polyanthrylene oligomers. FIG. 1a shows STM measurements and corresponding atomistic models demonstrating the synthesis of AGNRs starting from polyanthrylene chains assembled on a Au(111) substrate. Deposition of the molecular precursor on a substrate held at 470 K results in polyanthrylene oligomers (left) via surface-promoted monomer dehalogenation and intermolecular colligation of the resulting biradical intermediates Annealing at 670 K triggers cyclodehydrogenation resulting in 7-AGNRs (right). As shown in FIG. 1b, annealing at a reduced temperature of 600 K for 5 minutes results in partial cyclodehydrogenation and produces intra-ribbon heterojunctions. The STM image and the corresponding atomistic model show the realization of an atomically precise junction between a fully reacted N=7 AGNR of width w7=0.74 nm and a partially reacted polyanthrylene segment (N=5+) of width w5+=0.49 nm. STM images are acquired in constant current mode at 35 K (Vbias=1V 1=0.1 nA)

Example 2: Preparation of Segmented Graphene Nanoribbons from the Molecular Precursor 10,10-dibromo-9,9-bianthryl by STM Tip Induced Cyclodehydrogenation

(4) The cyclodehydrogenation is induced triggered by electron injection from the tip of the STM. Starting from heterojunctions obtained as outlined above in example 1 via moderate annealing, the length of 5+-AGNR regions is shortened in favor of 7-AGNR segments by controlled cyclodehydrogenation using voltage pulses applied to the STM tip.

(5) FIGS. 2a-c illustrate an example of a 7-GNR with a 5+-AGNR region, where the 5+-AGNR region is shortened by one unit via electron activated dehydrogenation. FIG. 2a (top left) shows STM image and corresponding atomistic model of a N=7 5+7 heterojunction obtained via thermally controlled annealing. FIG. 2b (bottom left) shows STM image and corresponding atomistic model of the previous heterojunction after tip induced dehydrogenation of one additional unit. The circle in FIG. 2a marks the lateral tip position during the electron activated dehydrogenation process. FIG. 2c (right) shows I-V curve revealing the activation of the reaction at 2.5V.

(6) FIG. 3 shows STM topographs illustrating examples of ribbon heterostructures formed by partial cyclodehydrogenation of the polyanthrylene oligomers at 600 K (Vbias=2V, 1=0.02 nA). FIG. 3a reveals two N=7 ribbons containing N=5+ segments. FIG. 3b shows a heterostructure consisting of N=7 AGNR and polyanthrylene oligomer segments. FIG. 3c shows a N=5+ AGNR polyantrhylene oligomer heterostructure.

(7) FIG. 4 shows an STM topograph illustrating a ribbon heterojunction with three different segments formed by partial cyclodehydrogenation of polyanthrylene oligomers at 600 K (Vbias=2V, 1=0.02 nA). The segments are polyanthrylene oligomer, N=5+ AGNR, and N=7 AGNR.

Example 3: Preparation of Segmented Graphene Nanoribbons by Thermal Annealation of Unsegmented Graphene Nanoribbons

(8) AGNRs are prepared starting from polyanthrylene chains assembled on a Au(111) substrate. Deposition of the molecular precursor on a substrate held at 470 K results in polyanthrylene oligomers via surface-promoted monomer dehalogenation and intermolecular colligation of the resulting biradical intermediates Annealing at 670 K triggers cyclodehydrogenation resulting in unsegmented 7-AGNRs. Post annealing at 710 K for 5 minutes results in segmented graphene nanoribbons by thermal annelation of the unsegmented ribbons.

(9) FIG. 5 shows an STM topograph illustrating a ribbon heterojunction formed by post-annealing the polyanthrylene oligomers at 710 K (Vbias=0.5V, 1=0.1 nA). At this temperature dehydrogenative edge coupling between individual N=7 AGNRs is triggered to form N=14 AGNR segments (of width w14=1.60 nm) within N=7 AGNRs (of width w7=0.74 nm).