Phthalocyanine and derived metal complexes (MPc) tend to aggregate and, thus, have low solubility in common solvents.
Benzene at 40 °C dissolves less than a milligram of H
₂Pc or CuPc per litre.
H
₂Pc and CuPc dissolve easily in sulfuric acid due to the protonation of the nitrogen atoms bridging the pyrrole rings.
Many phthalocyanine compounds are, thermally, very stable and do not melt but can be sublimed.
CuPc sublimes at above 500 °C under inert gases (nitrogen, CO
₂).
Substituted phthalocyanine complexes often have much higher solubility.
They are less thermally stable and often can not be sublimed.
Unsubstituted phthalocyanines strongly absorb light between 600 and 700 nm, thus these materials are blue or green.
Substitution can shift the absorption towards longer wavelengths, changing color from pure blue to green to colorless (when the absorption is in the near infrared).

There are many derivatives of the parent phthalocyanine, where either carbon atoms of the macrocycle are exchanged for nitrogen atoms or the peripheral hydrogen atoms are substituted by functional groups like halogens, hydroxyl, amine, alkyl, aryl, thiol, alkoxy and nitrosyl groups.
These modifications allow for the tuning of the electrochemical properties of the molecule such as absorption and emission wavelengths and conductance.
Phthalocyanine and derived metal complexes (MPc) tend to aggregate and, thus, have low solubility in common solvents. Benzene at 40 °C dissolves less than a milligram of H
₂Pc or CuPc per litre. H
₂Pc and CuPc dissolve easily in sulfuric acid due to the protonation of the nitrogen atoms bridging the pyrrole rings. Many phthalocyanine compounds are, thermally, very stable and do not melt but can be sublimed. CuPc sublimes at above 500 °C under inert gases (nitrogen, CO
₂). Substituted phthalocyanine complexes often have much higher solubility. They are less thermally stable and often can not be sublimed. Unsubstituted phthalocyanines strongly absorb light between 600 and 700 nm, thus these materials are blue or green. Substitution can shift the absorption towards longer wavelengths, changing color from pure blue to green to colorless (when the absorption is in the near infrared).
There are many derivatives of the parent phthalocyanine, where either carbon atoms of the macrocycle are exchanged for nitrogen atoms or the peripheral hydrogen atoms are substituted by functional groups like halogens, hydroxyl, amine, alkyl, aryl, thiol, alkoxy and nitrosyl groups. These modifications allow for the tuning of the electrochemical properties of the molecule such as absorption and emission wavelengths and conductance.
Phthalocyanine