Crystal structures of bis(phenoxy)silicon phthalocyanines: Increasing π-π interactions, solubility and disorder and no halogen bonding observed

Abstract

We report the syntheses and characterization of three solution-processable phenoxy silicon phthalocyanines (SiPcs), namely bis(3-methylphenoxy)- (phthalocyanine)silicon [(3MP)2-SiPc], CH30N8O2Si, bis(2-sec-butylphenoxy)( phthalocyanine)silicon [(2secBP)2-SiPc], C44H24I2N8O2Si, and bis(3-iodophenoxy)( phthalocyanine)silicon [(3IP)2-SiPc], C52H42N8O2Si. Crystals grown of these compounds were characterized by single-crystal X-ray diffraction and the π-π interactions between the aromatic SiPc cores were studied. It was determined that (3MP)2-SiPc has similar interactions to previously reported bis(3,4,5-trifluorophenoxy)silicon phthalocyanines [(345 F)2-SiPc] with significant π-π interactions between the SiPc groups. (3IP)2-SiPc and (2secBP)2-SiPc both experienced a parallel stacking of two of the peripheral aromatic groups. In all three cases, the solubility of these molecules was increased by the addition of phenoxy groups while maintaining π-π interactions between the aromatic SiPc groups. The solubility of (2secBP)2-SiPc was significantly higher than other bisphenoxy- SiPcs and this was exemplified by the higher observed disorder within the crystal structure.