Process for the synthesis of symmetric and unsymmetric oxygen bridged dimers of boron subphthalocyanines (mu-oxo-(BsubPc)(2)s)

摘要

A process for the gram scale synthesis of the oxygen bridged dimer of boron subphthalocyanine, mu-oxo-(BsubPc)(2), has been developed. During the development it was found that a wide range of reaction pathways under diverse conditions lead to mu oxo-(BsubPc)(2) formation. However, obtaining mu-oxo-(BsubPc)(2) as the main reaction product in appreciable yields and its subsequent isolation were extremely challenging. The best balance of purity, yield and conversion was achieved with a time controlled reaction of an equimolar reaction of HO-BsubPc with Br-BsubPc in the presence of K3PO4. The purification involved sequentially Soxhlet extraction, Kauffman column chromatography and train sublimation. We have repeated the process and yields ranged from 27 to 30% of pure, doubly-sublimed mu-oxo-(BsubPc)(2). This process also enabled the synthesis of unsymmetric mu-oxo-(BsubPc)(2)s by reaction of HO-BsubPc with Br-F(12)BsubPc, Cl-Cl(6)BsubPc and Cl-Cl(12)BsubPc. After synthesis the solution-state properties of the unsymmetric mu-oxo-(BsubPc)(2)s were investigated, and compared to the symmetric mu-oxo-(BsubPc)(2) and more broadly to other BsubPcs. The electronic properties of mu-oxo-(BsubPc)(2) were found to differ from its unsymmetric counterparts, but were found to be similar to halo-BsubPcs. Furthermore, the photophysical properties of mu-oxo-(BsubPc)(2), both symmetric and unsymmetric, differed greatly from all other known BsubPcs.