Phthalocyanine is a macrocyclic compound, It consists of four isoindole-class [(C6H4)C2N] units linked by four nitrogen
atoms to form a conjugated chain, which take play in hosting various different metal ions in its centre. This macrocyclic
structure like porphyrins(biopigments) is highly coloured Phthalocyanine derivatives derived from the basic compound of
(C6H4C2N)4N4 are used as light-fast blue or green pigments. The hosted metals and substituted groups result in distinct
colors; phthalocyanine (blue-green), copper phthalocyanine (blue), chlorinated copper phthalocyanine (green), and sulfonated
copper phthalocyanine (green). They have also been involved in the study of photosensitizer chemistry or metal complex
chemistry such as transition-metal complex catalyst chemistry for uniform polymerization, luminescence chemistry and
spectrophotometric analysis, organic synthesis and polymerization. Phthalocyanine pigments are used in enamels, linoleum,
inks, plastics, and rubber goods. Photoisomerizable phthalocyanines are used in rewritable CD or DVD printing. Some
phthalocyanines such as fluoraluminium phthalocyanine are used in cancer treatment. Due to pi-electron cloud overlaps,
phthalocyanines exhibit semiconductor property. Organic semiconductors have some merits of self radiation, flexibility, light
weight, easy fabrication, and low cost. They have been investigated as organic electroluminescence materials for the
applications in organic solar cells, biosensitizers and display devices such as OLED(Organic Light Emitting Diode),
OTFT(Organic Thin Film Transistor), Wearable Display, and e-paper.
Phthalocyanine green is a bluish green pigment with outstanding lightfastness and stability commercially produced since 1938.
Phthalocyanine blue is a bright blue pigment with outstanding properties which was in use by many modern painters such as Mondrian, Pollock, and others.
Phthalein is an important organic pigment. Its chromatography is mainly blue and green. It is of bright color and strong coloring force. It features excellent weatherability, heat resistance, solvent resistance, acid resistance and alkali resistance. It is widely used in paints, ink, plastic coloring, pigment printing, synthetic fiber raw coloring etc.. It can also be used as catalyst, grease, electrophotographic sensitizer, solar cell and so on. Its main variety is copper phthalocyanine (phthalocyanine blue). Metal phthalocyanines are also used in a small amount. Copper phthalocyanine has a variety of crystal forms, usually taking the alpha and beta forms. The hydrogen atoms on the benzene ring are replaced by halogen, and the color changes from blue to green.
Phthalein, also known as phthalocyanine, is a kind of dark compound. The structure is similar to porphyrin ring (or porphyrin complex, porphyrin). It is a dye consisting of four pyrrole nuclei with porphyrin ring structure. According to the molecular orbital theory, the conjugated system with this structure is very stable. Phthalocyanine is used as a blue to green pigment with the highest fastness. Afterwards, dyes with excellent properties are derived from various methods. It can be divided into metal phthalocyanine and non metal phthalocyanine. There are two types of metal phthalocyanines: the first type contains copper, iron, zinc, cobalt, platinum, etc.
The radius of the atom is close to the radius of the center gap of the phthalocyanine molecule. These metals are bonded to two nitrogen atoms in four nitrogen atoms by atomic bonds, and the other two nitrogen atoms are bonded by valence bonds. The other type contains sodium, potassium, barium, cadmium, magnesium, lead and so on. The atomic radius of the metal atom is too long and cannot form the valence bond with phthalocyanine. It can only be combined with two nitrogen atoms by atomic chain into salt. The former is treated with concentrated sulfuric acid, and the metal is not removed. It is slightly soluble in organic solvents and can be sublimed under high temperature and vacuum. The latter, in the case of acid or water, is easy to remove. It is insoluble in organic solvents and does not sublimate under high temperature and vacuum. Four benzene rings in phthalocyanine molecules are more easily substituted and sulfonated. The dyes derived from phthalocyanines include direct dyes, sulphur dyes, vat dyes, phthalocyanine dye (phthalocyanines), special water-soluble dyes and reactive dyes. Metal phthalocyanines are prepared by co heating of phthalic anhydride or phthalonitrile with metal or metal salts.
Phthalocyanine is a group of benzoporphyrins which
have strong pigmenting power, forming a family of dyes.
The basic structure of the molecule comprises four
isoindole groups (C6H4,)C2N, joined by four nitrogen
atoms. Four commercially important modifications are:
(a) metal free phthalocyanine (C6H4C2N)4, having a bluegreen
color,(b copper phthalocyanine in which a copper
atom is held by secondary valences of the isoindole
nitrogen atoms, (c) chlorinated copper phthalocyanine,
green, in which 15 to 16 hydrogen atoms are replaced by
chlorine, and (d) sulphonated copper phthalocyanine,
water-soluble and green, in which two hydrogens are
replaced by sulphonic acid groups. It is used in decorative
enamels and automotive finishes; chlorophyll and
haems have basic phthalocyanine structures in their
molecules.
Purify phthalocyanine by sublimation (two to three times) in an argon flow at 300-400Pa; and similarly for the Cu(II), Ni(II), Pb(II), VO(II) and Zn(II) phthalocyanine complexes. [Beilstein 26 III/IV 4255.]
