Aggregation of an octasubstituted phthalocyanine in dodecane solution

The Self‐Ordering Properties of Novel Phthalocyanines with Out‐of‐Plane Alkyl Substituents

“…In contrast, self-assembly into columnar aggregates broadens and blueshifts the Q-band as a result of exciton interactions. [18,19] Therefore, in order to obtain solid phthalocyanines that demonstrate similar light absorption characteristics to those of their dilute solutions, it was an attractive objective to place alkyl side chains on the macrocycle in such a way as to strongly disfavour aggregation but without perturbing the basic phthalocyanine chromophore. [20,21] The chosen strategy was to attach the alkyl chains to five-membered rings fused to the peripheral sites of the phthalocyanine so that the chains would project out of the molecular plane of the macrocycle and enforce separation through mutual steric interference.…”

“…[1, 11-15, 17, 29] The UV-visible absorption spectrum of a spincoated film of Pc 5(C 9 ) displays a l max of 620 nm (Figure 1), which is consistent with a blueshifted Q-band owing to the formation of an extended cofacial stack of phthalocyanine molecules, as would be expected for a columnar mesophase. [19,21] In the context of the objectives of the molecular design, it is perhaps surprising that columnar self-assembly is demonstrated for these derivatives, as the arrangement of the alkyl chains was expected to hinder cofacial self-association. A single-crystal X-ray diffraction (XRD) study of Pc 5(C 6 ) gave a clear insight into the columnar molecular arrangement formed by this series (Figure 2).…”

Synthesis and selected properties of metallo and metal-free 2,3,9,10,16,17,23,24 –octacarboxyphthalocyanines

“…The theory of interaction in phthalocyanine aggregates is generally based on molecular exciton coupling. 52,59,60 The hypsochromic spectra shift for the dimer 1164 cm -1 (688 nm637 nm) indicates a stack-like aggregation of molecules and suggests  interactions between Pc macrocycles in dimer and higher aggregates. The authors suggest that a hydrogen bonding between carboxylic groups is most likely of less importance in CuPcOC dimer formation and stability.…”

“…Aggregated compounds develop mainly due to interactions of delocalized  electrons of macrocycles. 52 However, the .functional groups as well as by oxygen atom (the creation of -oxo or -peroxo connections). The arrangement of the phthalocyanine macrocycles in the crystalline state in liquid crystal mesophases, in polymers which were created by the covalent bonds along the axis which connect the centers of macrocycles and in the associated compounds which occur in solutions is similar.…”

“…This arrangement in all cases is stacking. 52 In UV-vis spectra it is possible to trace the changes of the aggregation process, which are visible in the B band as well as the Q band. In the UV-vis spectrum of dimer complexes in solutions an intensive and broad band occurs in the Q band at about λ max = 630 nm ( Figure 3).…”