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SYNTHESIS AND SPECTRAL LUMINESCENT PROPERTIES OF AXIALLY SUBSTITUTED ZIRCONIUM (IV) AND HAFNIUM (IV) PHTHALOCYANINES Y. Gerasymchuk2, S. Volkov1, V. Chernii1, L. Tomachynski1 and S. Radzki2 1 V.I. Vernadski Institute of General and Inorganic Chemistry of NASU, Palladina Av. 32/34, 03680 Kyiv-142, Ukraine, E-mail: [email protected]. 2 Faculty of Chemistry, UMCS, M. Curie-Sklodowska Sq. 2, 20-031 Lublin, Poland Phthalocyanines and porphyrins have attracted considerable attention due to their unique properties and the potential applications of these complexes in catalysis, photosensitization reactions, liquid-crystalline systems, biomolecular processes and many other uses. Phthalocyanine macrocycle forms the πconjugated system that differs distinctly from the most of organic compounds by a level of π-electron delocalization and a high level of symmetry. The electronic absorption spectra of phthalocyanine complexes consist of two bands: В (Soret) and Q in UV and visible region, respectively. Excitation in the Soret region is the consequence of a2u-eg, (π-π*) transitions, and the absorption in the Q-region is the consequence of a1u-eg, (π-π*) transitions. Introducing out of plane ligands to the central atom influences substantively on π-electron conjugation of the macromolecule and decreases a level of symmetry of the molecule. This work report the investigation of spectral properties of zirconium (IV) and hafnium (IV) phthalocyanine complexes with gallic, 5-sulfosalicylic, oxalic acids and methyl esther of gallic acid as axial ligands. Absorption measurements were carried out using a Carl Zeiss- Jena M42 spectrophotometer. Spectra were recorded between 300 and 900 nm at temperature of 21±1 ° C. O O S O O OH OH O M M O O O OH Gallic acid (Ia, Ib) 5-Sulfosalicylic acid (IIa, IIb) O O O O O CH3 M M O O O HO Oxalic acid (IIIa, IIIb) Methyl Esther of Gallic acid (IVa, IVb) Axial ligands coordinated to the central metal atom of phthalocyanine M=Zr(IV)-(a), Hf(IV)-(b) Fluorescence measurements were carried out using a Fluoromax-2 spectrofluorometer (Jobin Yvon-Spex, Horiba Group), with the detector oriented at 90° relative to the light source and using 1-cm quartz cell. All the fluorescent spectra were excited at the wavelength of the Soret band and recorded at a temperature of 21±1 °C in the range 300-850 nm. Absorption and emission spectra were recorded digitally and the Sigma Plot (Jandel Corp.) program was used in manipulation and plotting the data. As for all phthalocyanines, absorbance spectra of axially substituted Zr(IV) and Hf(IV) phthalocyanines are characterized by presence of ultraviolet Soret band (λmax in the range of 335 to 350 nm) and visible Q band (λmax in the range of 675 to 701 nm) (Table). The wavelengths of absorbance band maxima in the Soret range origin had low level of correlation with the polarity of the solvents. The position of λmax in the Q region depends on the solvent polarity - the lower is Reichardt’s empirical parameter of polarity for solvent, the higher shift of λ max into the red is observed. The red shift of absorbance band maxima in the Q region for the solvents with relatively high polarity (MeOH, EtOH) and for the solvents with relatively low polarity (CH2Cl2, CHCl3) is up to 10 nm. Table. Dependence of the absorbance and emission band maxima of phthalocyanine complexes from the type of central metal atom and axial ligand in the DMSO solution (ΔS [nm] = Stokes shift) Investigated complexes Absorption λmax [nm] Excitation λ [nm] Emission λmax [nm] ΔS [nm] S Q Ia 342 685 420 499 730 45 Ib 349 690 420 474 735 45 IIa 348 688 420 539 725 37 IIb 347 687 420 525 732 45 IIIa 343 681 410 496 726 45 IIIb 341 678 410 478 737 59 IVa 349 688 410 498 735 49 IVb 349 691 410 475 737 44 In the fluorescence spectra of the DMSO solutions, when excitation λ max is 410 or 420 nm, the maxima of emission spectra for all the investigated complexes are located in the range from 725 to 737 nm. Moreover, for the complexes with the same axial ligands, λmax of emission for Hf(IV) complexes are 10-15 nm shifted into the red in comparison to λ max of Zr(IV) emission. The Stocks shifts for all investigated complexes are about 50 nm.