title: Optical and thermal properties of azo derivatives of salicylic acid thin films.
abstract: N-acryloyl-4-aminosalicylic acid (4-AMSA), monomer (HL) and 5-(4'-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are synthesized and characterized with various physico-chemical techniques. Thin films of 5-(4'-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are prepared by spin coating technique. The X-ray diffraction (XRD) patterns of 4-aminosalicylic acid (4-ASA) and its derivatives are investigated in powder and thin film forms. Thermal properties of the compounds are investigated by thermogravemetric analysis (TGA). The optical energy gap and the type of optical transition are investigated in the wavelength range (200-2500 nm) for 4-ASA, HL and HLn. The values of fundamental energy gap (Eg) are in the range 3.60-3.69 eV for all compounds and the type of optical transition is found to be indirect allowed. The onset energy gap Eg(∗) appeared only for azodye compounds is found to be in the range 0.95-1.55 eV depending on the substituent function groups. The refractive index, n, shows a normal dispersion in the wavelength range 650-2500 nm, while shows anomalous dispersion in the wavelength rang 200-650 nm. The dispersion parameters ε∞, εL, Ed, Eo and N/m(∗) are calculated. The photoluminescence phenomena (PL) appear for thin films of 4-ASA and its derivatives show three main emission transitions.
authors.affiliation: Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt.
authors.forename: M M
authors.initials: MM
authors.lastname: Ghoneim
authors.affiliation: Physics Department, Faculty of Science, Damietta University, Damietta, Egypt.
authors.forename: N A
authors.initials: NA
authors.lastname: El-Ghamaz
authors.affiliation: Chemistry Department, Faculty of Science, Damietta University, Damietta, Egypt. Electronic address: elsonbatisch@yahoo.com.
authors.forename: A Z
authors.initials: AZ
authors.lastname: El-Sonbati
authors.affiliation: Chemistry Department, Faculty of Science, Damietta University, Damietta, Egypt.
authors.forename: M A
authors.initials: MA
authors.lastname: Diab
authors.affiliation: Chemistry Department, Faculty of Science, Damietta University, Damietta, Egypt.
authors.forename: A A
authors.initials: AA
authors.lastname: El-Bindary
authors.affiliation: Chemistry Department, Faculty of Science, Damietta University, Damietta, Egypt.
authors.forename: L S
authors.initials: LS
authors.lastname: Serag
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D008567:Membranes, Artificial; D012459:Salicylates / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001391:Azo Compounds; D008567:Membranes, Artificial; D012459:Salicylates
keywords: Azo salicylic acid; Fluorescence; Spin coating; Thermal and optical properties of thin films; X-ray diffraction