meso-Functionalizations of BIII Subporphyrin with BIII meso-Lithiosubporphyrin.

Boron(III) meso-lithiosubporphyrin was prepared by bromine-lithium exchange of B-tolyl B-III meso-bromosubporphyrin with n-butyllithium at -98 degrees C. The resulting subporphyrinyllithium was treated with various electrophiles such as benzophenone, N,N-dimethylformamide, CO2, chlorotrimethylsilane, N-fluorobenzenesulfonimide, and dimesitylboryl fluoride to give the corresponding meso-functionalized B-III subporphyrins. The nucleophile was also used to construct B-III subporphyrin dimers such as bis(B-III subporphyrinyl)ketone, bis(B-III subporphyrinyl)carbinol, and disilane-bridged B-III subporphyrin dimer. The structural, optical, and electrochemical properties of these meso-functionalized B-III subporphyrins were examined by UV/Vis absorption and fluorescence spectroscopy, electrochemical studies, and DFT calculations.