Regioregular synthesis of azaborine oligomers and a polymer with a syn conformation stabilized by N-H⋅⋅⋅π interactions.
The regioregular synthesis of the first azaborine oligomers and a corresponding conjugated polymer was accomplished by Suzuki-Miyaura coupling methods. An almost perfectly coplanar syn arrangement of the heterocycles was deduced from an X-ray crystal structure of the dimer, which also suggested that NH⋅⋅⋅π interactions play an important role. Computational studies further supported these experimental observations and indicated that the electronic structure of the longer azaborine oligomers and polymer resembles that of poly(cyclohexadiene) more than poly(p-phenylene). A comparison of the absorption and emission properties of the polymer with those of the oligomers revealed dramatic bathochromic shifts upon chain elongation, thus suggesting highly effective extension of conjugation.
Department of Chemistry, Boston College, Chestnut Hill, MA 02467 (USA).
Andrew W
AW
Baggett
Department of Chemistry, Rutgers University-Newark, Newark, NJ 07102 (USA).
Fang
F
Guo
Department of Chemistry, Boston College, Chestnut Hill, MA 02467 (USA).
Bo
B
Li
Department of Chemistry, Boston College, Chestnut Hill, MA 02467 (USA). shihyuan.liu@bc.edu.
Shih-Yuan
SY
Liu
Department of Chemistry, Rutgers University-Newark, Newark, NJ 07102 (USA). fjaekle@rutgers.edu.
Frieder
F
Jäkle
boron; conjugation; cross-coupling; heterocycles; polymers