Crystal and Solid-State Arrangement Trends of Halogenated Boron Subphthalocyanines

A series of new crystal structures for the boron subphthalocyanine (BsubPc) derivatives chloro hexachloro BsubPc (Cl-Cl₆BsubPc), chloro dodecachloro BsubPc (Cl-Cl₁₂BsubPc), bromo/chloro hexachloro BsubPc (Br_0.27|Cl_0.73-Cl₆BsubPc), bromo dodecachloro BsubPc (Br-Cl₁₂BsubPc), and pentafluorophenoxy dodecachloro BsubPc (F₅PhO-Cl₁₂BsubPc) are reported. By combining these new crystal structures with a series of previously published structures into a comprehensive study, we have outlined several new structure crystal property/solid-state arrangement relationships for this expanded list of BsubPc derivatives. Parameters that were examined to establish the relationships include (a) geometric descriptors of the BsubPc molecular structure including the bowl shape of the BsubPcs; (b) molar density of the crystals; and (c) void volume fraction (Φ). Variations in the peripheral substituents (from hydrogen to fluorine and chlorine) were found to have a profound effect on the solid-state arrangement. No significant changes were noted when the axial substituent was varied from chlorine to bromine, whereas replacement of the axial halide with a pentafluorophenoxy fragment resulted in a notable change (as expected). It was also found that Cl-C₁₂BsubPc (and its derivatives) had a high tendency to co-crystallize with solvents (form solvates), which resulted in a significantly different solid-state arrangement. We believe the observations detailed in this paper will lead to routes to engineer the crystallization of BsubPcs to facilitate tailored solid-state arrangement and properties