Coordination-driven assemblies of thioindigo and phthalocyanine chromophores: tuning optical absorption and magnetic interactions

Dyes and Pigments. 2026. Vol. 254. Article 113957.

Kolin N., Nazarov D., Krivenko K., Kuzmin A. V., Faraonov M., Khasanov S., Otsuka A., Kitagawa H., Konarev D.

Interaction of thioindigo dianions with metal phthalocyanines, MPc, where M = MgII, MnII, AlIIICl and SiIVCl2, in the presence of cryptand[2.2.2] produces anionic and neutral complexes: {Crypt(K+)}2{(trans-thioindigo2−)⋅(MgIIPc)2}2−⋅2C6H4Cl2 (1); {Crypt(Cs+)}2{(trans-thioindigo2−)⋅(MnIIPc)2}2− (2), {Crypt(K+)}{(cis-Hthioindigo−)2⋅(AlIIIPc)}− (3) and {(cis-Hthioindigo−)2⋅(SiIVPc)} (4). Bidentate thioindigo2− ligand forms symmetric binuclear dimers in 1 and 2 with short M-O(thioindigo2−) bonds of 1.899(2) and 1.984(6) Å length for MgII and MnII, respectively. The {(trans-thioindigo2−)⋅(MgIIPc)2}2− dimers are diamagnetic in 1 whereas the {(trans-thioindigo2−)⋅(MnIIPc)2}2− dimers in 2 contain high-spin MnII (S = 5/2) ions weakly antiferromagnetically coupled through the diamagnetic thioindigo2− bridge with exchange interaction of J = −0.27 cm−1 at g = 2.0081. Zero-field splitting parameter D was directly determined from EPR to be 0.071 cm−1. When two thioindigo− anions coordinate to metal phthalocyanines in 3 and 4 short M–O(thioindigo−) bonds of 1.995(2) Å length for AlIII and 1.815(4) and 1.775(3) Å length for SiIV are formed. Short O⋯O contacts of 2.59–2.74 Å length in the thioindigo− anions indicate protonation of non-coordinated oxygen atoms to form strong hydrogen O–H⋯O− bonding linked these oxygen atoms. We found that the length of coordination O–M bonds affects the O⋯O distances and correspondingly hydrogen bonding in the protonated thioindigo anions. Strongest bonding is observed for the longest O–Al bonds. Optical spectra of 1–4 contain absorption bands of metal phthalocyanines and weaker bands of thioindigo anions. Q-bands of starting metal phthalocyanines have splitting in the spectra. However, lower energy components of this band at 735–838 nm disappear at the complex formation. The OH groups participated in the hydrogen bonding manifest bands at 2600–2700 cm−1 characteristic of such type of bonds.

Keywords: phthalocyanine, фталоцианин