SYNTHESIS AND SPECTRAL PROPERTIES OF PHTHALOCYANINES WITH 2,3,5-TRIMETHYLPHENOXY AND NITRO GROUPS

Phthalonitrile containing a 2,3,5-trimethylphenol fragment and a nitro group at the periphery was synthesized on the basis of 4-bromo-5-nitrophthalonitrile. Tetrakis-2,9,16,24-(2,3,5-trimethylphenoxy)tetrakis-3,10,17,25-nitrophthalocyanine and its metallocomplexes with zinc and magnesium were synthesized on its basis by the "nitrile" method. The latter was used to obtain the corresponding phthalocyanine - ligand. All synthesized compounds were characterized by differential scanning calorimetry, elemental analysis, 1H NMR, infrared spectroscopy and MALDI-TOF spectrometry. Spectral-luminescent properties, as well as acid-base properties of the phthalocyanine - ligand, were studied for phthalocyanines. It was found that the compounds under consideration are thermally stable up to 300 °C. When studying the electronic absorption spectra, it was found that the nature of the complexing metal has virtually no effect on the position of the Q bands of the synthesized compounds in DMF and chloroform. The transition to pyridine is accompanied by a strong hypsochromic shift of the Q bands of the synthesized metal phthalocyanines, and the spectra of solutions in concentrated sulfuric acid are characterized by a bathochromic shift of the Q bands of all the compounds considered by more than 100 nm. All the phthalocyanines considered in this work have luminescent properties. It is noted that the introduction of nitro groups into the molecule of mixed-substituted zinc phthalocyanine with trimethylphenoxy and nitro groups sharply increases the Stokes shift while maintaining the quantum yield, i.e. without losing the luminescence efficiency. The quantum yield depends on the nature of the complexing metal and decreases in the series: ZnPc > MgPc > H2Pc. Electronic absorption spectra of Tetrakis-2,9,16,23-(2,3,5-trimethylphenoxy)tetrakis-3,10,17,24-nitrophthalocyanine in basic solvents (pyridine, DMF, DMSO) contain a single unsplit Q-band. In addition, this compound exhibits the properties of a dibasic NH-acid and forms a stable proton-transfer complex that loses its kinetic stability upon addition of n-butylamine. For citation: Demidova E.I., Znoyko S.A., Molchanov E.E., Maizlish V.E., Petrov O.A. Synthesis and spectral properties of phthalocyanines with 2,3,5-trimethylphenoxy and nitro groups. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 2. P. 52-61. DOI: 10.6060/ivkkt.20256802.7160.