Preparation of highly thermally stable and conductive Schiff base polymer: Molecular weight monitoring and investigation of antimicrobial properties

The synthesis of novel water-soluble zinc (II) phthalocyanine based photosensitizers and exploring of photodynamic therapy activities on the PC3 cancer cell line

In this study, Schiff base substituted phthalocyanine complexes (Zn1c, Zn2c) and their quaternized derivatives (Q-Zn1c, Q-Zn2c) were synthesized for the first time. Their structures have been characterized by FT-IR, 1H-NMR, UV-Vis, mass spectrometry and elemental analysis as well as. The photophysicochemical properties (fluorescence, singlet oxygen and photodegradation quantum yield) of these novel complexes were investigated in dimethylsulfoxide (DMSO) for both non-ionic and quaternized cationic phthalocyanine complexes and in aqueous solution for quaternized cationic phthalocyanine complexes. Water soluble cationic phthalocyanine compounds gave good singlet oxygen quantum yield (0.65 for Q-Zn1c, 0.66 for Q-Zn2c in DMSO; 0.65 for Q-Zn2c in aqueous solution). The binding of Q-Zn1c and Q-Zn2c to BSA/DNA was studied by using UV-Vis and fluorescence spectroscopy and these. Studies indicate that the mechanism of BSA quenching by quaternized zinc(II) phthalocyanines was static quenching. Quaternized zinc(II) phthalocyanines interacted with ct-DNA by intercalation. Quaternized zinc(II) phthalocyanines caused a decrease in cell viability and triggered apoptotic cell death after PDT was applied at a concentration that did not have a toxic effect on their own. Q-Zn1c and Q-Zn2c mediated PDT reduced the activity of SOD, CAT, GSH while increased MDA level in the prostate cancer cells. Furthermore, expression of apoptotic proteins after PDT was examined. The results revealed that the synthesized water soluble quaternized zinc(II) phthalocyanine complexes (Q-Zn1c and Q-Zn2c) are promising potential photosensitizers for PDT.

Green Synthesis, Characterization, Antimicrobial and Anticancer Screening of New Metal Complexes Incorporating Schiff Base

A Schiff base ligand of o-vanillin and 4-aminoazobenzene and its transition metal complexes of Ni(II), Co(II), Zn(II), Cu(II), Mn(II), and Zr(IV) were prepared under microwave irradiation as a green approach compared to the conventional method. The structures of new compounds have been characterized and elucidated via elemental and spectroscopic analyses. In addition, magnetic susceptibility, electron spin resonance, and electronic spectra of the synthesized complexes explained their geometrical structures. The thermal stability of Cu(II), Zn(II), and Zr(IV) complexes was studied by thermo-gravimetric analyses (TGA). Coats-Redfern and Horowitz-Metzger equations were used to calculate the thermal and dehydration decomposition activities of proposed structures kinetically. Surface morphologies of the solid compounds were imaged by scanning electron microscopy (SEM). The particle size of prepared complexes was measured by using a particle size analyzer at a diffraction angle of 10.9°. The geometry structures of the synthesized compounds were verified utilizing electronic spectra, ESR spectrum, and magnetic moment value. The newly synthesized compounds were screened for antimicrobial activity. Also, the anticancer activity of the free Schiff base ligand and its metal complexes were studied against two cell lines: human colon (HCT-116) and human liver cancer cells (HepG-2). The obtained results showed that the Cu(II) complex displayed the highest cytotoxic activity (IC₅₀ = 18 and 22 μg/mL for HepG-2 and HCT, respectively) compared to the free Schiff base ligand.

Synthesis, Crystal Structures, and Spectroscopic Characterization of Bis-aldehyde Monomers and Their Electrically Conductive Pristine Polyazomethines

Bis-aldehyde monomers 4-(4′-formyl-phenoxy)benzaldehyde (3a), 3-methoxy-4-(4′-formyl-phenoxy)benzaldehyde (3b), and 3-ethoxy-4-(4′-formyl-phenoxy)benzaldehyde (3c) were synthesized by etherification of 4-fluorobenzaldehyde (1) with 4-hydroxybenzaldehyde (2a), 3-methoxy-4-hydroxybenzaldehyde (2b), and 3-ethoxy-4-hydroxybenzaldehyde (2c), respectively. Each monomer was polymerized with p-phenylenediamine and 4,4′-diaminodiphenyl ether to yield six poly(azomethine)s. Single crystal X-ray diffraction structures of 3b and 3c were determined. The structural characterization of the monomers and poly(azomethine)s was performed by FT-IR and NMR spectroscopic techniques and elemental analysis. Physicochemical properties of polymers were investigated by powder X-ray diffraction, thermogravimetric analysis (TGA), viscometry, UV–vis, spectroscopy and photoluminescence. These polymers were subjected to electrical conductivity measurements by the four-probe method, and their conductivities were found to be in the range 4.0 × 10⁻⁵ to 6.4 × 10⁻⁵ Scm⁻¹, which was significantly higher than the values reported so far.

Synthesis, characterization and solid state conductivity of nano-size ionic Schiff base polymers of Cu2+, Zn2+ and VO2+ containing viologen moieties

The new nano size ionic metallo-Schiff base polymers (IMSPs) were synthesized by reaction of Schiff base ligand of L and VO (acac)₂, ZnCl₂ and CuCl₂. The solid state conductivity measurements candidate them as new metallo-organic semiconductors.