Synthesis of the (4,4′-bipyridine)(5,10,15,20-tetratolylphenylporphyrinato)zinc(II) bis(4,4-bipyridine) disolvate dehydrate and evaluation of its interaction with organic dyes

The synthesis, photo-physical properties and the optical spectroscopy of the starting materials H₂TTP (1), [Zn(TTP)](2) and [Zn(TTP)(4,4′-bpy)]0.2(4,4′-bpy.H₂O) (3) (TTP = meso-tetratolylporphyrin) are reported. The X-ray molecular structure of the compound shows that this species is a five-coordinated zinc(II) metalloporphyrin. Complex 3 crystallized in the monoclinic crystal system, space group C 2/c with a = 15.7541(2) (Å), b = 18.6688(3) (Å), c = 21.6410(4) (Å), β = 103.025(1)° V = 6201.08(17) (ų), d_calc, (g/cm³) = 1.327 and Z = 4. Data gleaned from the optical spectroscopy reveals that the bathochromic shift of the Soret and Q absorption bands is connected mainly to the distortion of the 24-atom average plane of the porphyrinic macrocycle and the values of the optical gap E_g-op of the metallized species (2–3) are higher than that of the free base porphyrin H₂TTP. The association constant (K_as) values of the zinc bpy-TTP derivative were also determined. Further, the interaction of the studied complexes with two organic dyes, namely Acid Blue 25 and Calmagite, was performed in an aqueous medium in batch mode. The results exhibited that the removal of Calmagite and Acid Blue 25 using complex 1 are 32% and 24%(C₀30 mg/L, pH 6, T 25 °C). However, the target removal of these dyes using the system H₂O₂-complex 3 reached 46% and 35% (C₀ 30 mg/L, pH 6, H₂O₂ concentration 4 mL/L, T 25 °C).