Synthesis, Spectroscopic Characterization and Polymerization Abilities of Blue and Green Light Emitting Oxazol-5-one Fluorophores.

New fluorescent thiophenyl group containing oxazol-5-one fluorophores of 3a (4-(3-thiophenylmethylene)-2-phenyloxazol-5-one), 3b (4-(3-thiophenylmethylene)-2-(4-tolyl)oxazol-5-one) and 3c (4-(3-thiophenylmethylene)-2-(4-nitrophenyl)oxazol-5-one) were synthesized and characterized. The newly synthesized oxazol-5-ones absorption and fluorescence characteristics were studied in some solvents of varying polarities. The heterocyclic chromophores were fluorescent, with two of them, 3a and 3b, emitting blue light, whilst the other one, 3c, emitting green light. The emission maxima of the derivatives varied between 415 and 572 nm according as the extent of conjugation and solvent polarity. As solvent polarity increased, 3c derivatives emission spectra displayed a large bathochromic shift, which revealed the considerable change of the dipole moment of the fluorescent structure because of an intramolecular charge transfer interaction. Furthermore, oxazolones polymerization ability via the thiophenyl group linked to the oxazol-5-one heterocycle showed that copolymerization of 3a was achieved, but homopolymerization was not observed.

Transition Metal (II) Complexes with a Novel Azo-azomethine Schiff Base Ligand: Synthesis, Structural and Spectroscopic Characterization, Thermal Properties and Biological Applications.

The pyrimidine based azo-linked Schiff base ligand, 5-benzoyl-1-((E)-(2-hydroxy-3-methoxy-5-((E)phenyldiazenyl)benzylidene)amino)-4-phenylpyrimidin-2(1H)-one (HL), and its transition metal (II) complexes were synthesized and defined by using 1H-NMR, 13C-NMR, Elemental analysis, FT-IR, MS, UV-vis, molar conductance, magnetic susceptibility and thermal analysis techniques. According to the conductance data obtained indicate all of the metal complexes have non-electrolytic nature. Square pyramidal geometry for Pd(II) and octahedral geometry for all the other complexes synthesized was concluded from the electronic absorption spectra and magnetic susceptibility measurements of the complexes. Investigation of the significant infrared bands of the active groups in the ligand and the solid complexes alludes that HL is coordinated to the metal ions ONO tridentate manner. Moreover, the absorption and emission properties of the azo-azomethine based ligand and its complexes were investigated. The results obtained show that fluorescence emissions of the ligand and its metal (II) complexes depend on the type of transition metal ions and the derivatives displayed moderate Stokes' shift values between 44 and 107 nm. All the compounds exhibited superb photostability. Further, antioxidant, antimicrobial and pBR322 plasmid DNA cleavage activities were investigated. All compounds showed good DPPH• (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and complexes of [MnL2]•H2O and [NiL2]•H2O exhibited excellent metal chelating activity. All the compounds tested demonstrated two strand DNA cleavage activities.

Spectrofluorimetric and Potentiometric Determination of Acidity Constants of 4-(4'-Acetyloxy-3'-Methoxybenzylidene)-5-Oxazolone Derivatives.

4-(4'-acetyloxy-3'-methoxybenzylidene)-5-oxazolone fluorescent molecules bearing four different aryl groups attached to the 2-position of 5-oxazolone ring have been investigated by spectrophotometric and potentiometric techniques in solution media. The acidity constants (pKa) of the fluorescent molecules were precisely determined in acetone, acetonitrile, dimethylformamide and in 1:1 mixture of toluene-isopropanol. The studied derivatives were titrated with tetrabutylammonium hydroxide and non-aqueous perchloric acid by scanning the basic and acidic region of the pH scale. A computerizable derivative method was used in order to descript precisely the end point and pKa values. The molecules investigated performed well-shaped and stoichiometric potentiometric titration curves.

Novel multiporphyrin functionalized single-walled carbon nanotubes.

Porphyrin monomers, 5,15-bis(4-(2,5,8,11-tetraoxatridecan-13-yloxy)phenyl)-10,20-bis(3-iodophenyl)porphyrin zinc (5a) and 5,10-bis(4-(2,5,8,11-tetraoxatridecan-13-yloxy)phenyl)-15,20-bis(3-iodophenyl)porphyrin zinc (5b), and their oligomers 6a and 6b were synthesized and characterized. The titration experiment of the monomers was carried out in THF by changing the solution percent of water. The optical properties (UV-vis and fluorescence spectra) of the monomers that possess slightly red-shifted optical spectra in water compared to the spectra obtained in THF are reported. The newly prepared porphyrin constructs were also mixed with SWCNTs to generate noncovalent hybrid materials.