Compound comprising phenyl pyridine units

1. A compound of formula I:

wherein

R 1 is independently at each occurrence a C 1 -C 20 aliphatic radical, a C 3 -C 20 aromatic radical, or a C 3 -C 20 cycloaliphatic radical; and

a is independently at each occurrence 0, or an integer ranging from 1 to 4.

2. The compound of claim 1 , having chemical formula II

3. A polymer comprising structural units derived from a compound of formula I

wherein

R 1 is independently at each occurrence a C 1 -C 20 aliphatic radical, a C 3 -C 20 aromatic radical, or a C 3 -C 20 cycloaliphatic radical; and

a is independently at each occurrence 0, or an integer ranging from 1 to 4.

4. The polymer of claim 3 , additionally comprising structural units of formula

5. A polymer comprising structural units derived from a compound of formula II

6. The polymer of claim 5 , additionally comprising structural units of formula

7. An optoelectronic device comprising a polymer comprising structural units derived from formula I

wherein

R 1 is independently at each occurrence a C 1 -C 20 aliphatic radical, a C 3 -C 20 aromatic radical, or a C 3 -C 20 cycloaliphatic radical; and

a is independently at each occurrence 0, or an integer ranging from 1 to 4.

8. The optoelectronic device of claim 7 , wherein the polymer additionally comprises structural units of formula

9. The optoelectronic device of claim 7 , wherein the optical electronic device is a single layer OLED.

10. The optoelectronic device of claim 9 , further comprising at least one blue, yellow, orange, green or red phosphorescent dye.

11. An optoelectronic device comprising a polymer having structural units derived from a compound of formula II

12. The optoelectronic device of claim 11 , wherein the polymer additionally comprises structural units of formula