Regioisomer-Free C 4h β-Tetrakis(tert-butyl)metallo-phthalocyanines: Regioselective Synthesis and Spectral Investigations

Iridium-catalysed 3,5-bis-borylation of phthalonitrile enables access to a family of C4h octaarylphthalocyanines

Ir-catalysed borylation of phthalonitrile produces both 4-(Bpin)phthalonitrile (1) and 3,5-bis(Bpin)phthalonitrile (2), which are potential divergent intermediates for the synthesis of functionalized phthalocyanines. To exemplify the utility of 2, we have prepared a series of 3,5-bis-arylphthalonitriles that in turn undergo sterically controlled regioselective cyclotetramization to give previously unknown C4h 1,3,8,10,15,17,22,24-octaarylphthalocyanines.

Temperature-dependent changes in the molecular orientation and visible color of phthalocyanine films

A simple phthalocyanine zinc complex exhibits a visible color change in response to weak external stimuli, i.e., changes in solvent and temperature. Its chromism was attributed to its controlled aggregation via weak interactions between the central metal and peripheral oxygen atoms. In solution, intense absorption and fluorescence bands appeared in both the longer-wavelength and NIR region in non-coordinating solvents, while a simple sharp Q band was observed in coordinating solvents. Variable-temperature absorption spectra and fluorescence lifetime measurements were used to characterize the aggregation-induced absorption and emission in non-coordinating solvents. A selective aggregation–disaggregation process was also observed in thin films of this phthalocyanine zinc complex, and the optical properties of the film depend on the annealing temperature. The changes in the NIR region lead to a sizable visible color change that is recognizable by the naked human eye. The temperature-dependent control of the aggregation process in the thin film was confirmed using operando spectroscopy techniques.

A simple phthalocyanine zinc complex exhibits a visible color change in response to weak external stimuli, i.e., changes in solvent and temperature.

Super-Sensitive Protonation Behavior of Trifluoroethoxy-Substituted Phthalocyanines and Their Application to Solvent Discrimination

The super-sensitive protonation behavior of trifluoroethoxy-substituted phthalocyanines (TFEO-Pcs) was carefully studied using UV-vis and fluorescence spectroscopy, as well as computational calculations. The practical utility of TFEO-Pcs in sensor technology was demonstrated by identifying chloroform samples from different commercial sources.

Synthesis of Phthalocyanines with a Pentafluorosulfanyl Substituent at Peripheral Positions

The pentafluorosulfanyl (SF5) group is more electronegative, lipophilic and sterically bulky relative to the well-explored trifluoromethyl (CF3) group. As such, the SF5 group could offer access to pharmaceuticals, agrochemicals and optoelectronic materials with novel properties. Here, the first synthesis of phthalocyanines (Pcs), a class of compounds used as dyes and with potential as photodynamic therapeutics, with a SF5 group directly attached on their peripheral positions is disclosed. The key for this work is the preparation of a series of SF5-containing phthalonitriles, which was beautifully regio-controlled by a stepwise cyanation via ortho-lithiation/iodination from commercially available pentafluorosulfanyl arenes. The macrocyclization of the SF5-containing phthalonitriles to SF5-substituted Pcs required harsh conditions with the exception of the synthesis of β-SF5-substituted Pc. The regiospecificity of the newly developed SF5-substituted Pcs observed by UV/Vis spectra and fluorescence quantum yields depend on the peripheral positon of the SF5 group.