Synthesis and Photophysical Characterization of Novel Octa(Carbazolyl)Phthalocyanine Derivatives Exhibiting Unique Solvatochromic Effects
Shereen Abdul Majeed
A Dissertation Submitted to the College of Graduate Studies in Partial Fulfilment of the Requirements for PhD
Degree in: Chemistry
Prof. Saad Ali Makhseed
Kuwait - February 2019
This thesis explores the synthesis of five novel carbazole substituted phthalocyanine complexes with different metals, where M = Zn2+ (4), 2H+ (7), Mg2+ (8), Ga3+ (9) and In3+ (10) in addition to the derivatives of two zinc phthalocyanine complexes bearing ter-butyl (5) and bromine (6) groups on the carbazole. The synthesized complexes were characterized by 1H and 13C NMR, FT-IR, UV-Visible, mass spectroscopy and elemental analyses. The structural features of 4, 5 and 8 and their precursor phthalonitrile derivatives were studied by single crystal X- ray diffraction technique. From the crystal structure of 4 and 8, it was found that the plane of the peripheral carbazole moieties are about 60o twisted with respected to the Pc plane and this twisted orientations are very efficient in eliminating the possibility of face-to-face phthalocyanine-centred H-type aggregation. Spectroscopic data were correlated with density functional theory (DFT) and time-dependent DFT calculations on 4 and 9 which showed the effect of carbazole groups on decreasing the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the studied complexes. Gallium phthalocyanine complex (9) in addition to the three different substituents of carbazole containing zinc phthalocyanine complexes (4-6) were conjugated to graphene quantum dots (GQDs) via π-π stacking. The morphology, sizes, and crystallinity of the nanoconjugates were determined using Raman, EDX, TEM and XRD. Photophysical measurements; fluorescence quantum yields, fluorescence lifetimes and singlet oxygen quantum yields of the prepared complexes in different solvents exhibited interesting properties due to the Intra Ligand Charge Transfer (ILCT) effect and consequently prolonged fluorescence excited state life time (5.00 ns) with high singlet oxygen quantum yield (ФΔ = 0.825). The nonlinear optical (NLO) properties of (4-6) and 9 alone and when conjugated to nanomaterial in different solvents, as well as after embedding the complexes in thin films were studied. The effects of different substituents, central metal ions and solvents on the NLO properties of metallophthalocyanines were evaluated. There are enhancement in the photophysical properties of the complexes upon conjugations with the nanomaterial. Fluorescence quantum yields, fluorescence lifetimes, triplet quantum yields and triplet lifetimes were measured for complexes 4, 6, 9 and their conjugates in DMSO.