title: Fluorescent tetraruthenated porphyrins embedded in monolithic SiO2 gels by the sol-gel process.
abstract: In this work silica gels have been prepared by a sol-gel method using tetraethylorthosilicate as gel precursor. The tetraruthenated porphyrins H2(3-TRPyP), Co(3-TRPyP), and H2(4-TRPyP) were incorporated into the systems during gel formation without problems commonly found in the process, such as aggregation. Spectroscopic studies of the resulting silica gels revealed the presence of absorption bands in the range 200-400 nm associated with the transitions of the groups ruthenium-bipyridine, along with the Soret band at the same wavelengths observed in solution. The porphyrins were found to preserve fluorescence emission properties in the range 650-700 nm even after the aging period. Study of the thermal behavior and decomposition kinetics evidenced that the porphyrin H2(4-TRPyP) is the least stable of the group and that all compounds decompose according to first-order kinetics.
authors.affiliation: Departamento de Química-UFS, CEP 49100-000, São Cristóvão, SE, Brazil.
authors.forename: Shirleny F
authors.initials: SF
authors.lastname: Santos
authors.forename: Marcelo L
authors.initials: ML
authors.lastname: Santos
authors.forename: Luis E
authors.initials: LE
authors.lastname: Almeida
authors.forename: Nivan B
authors.initials: NB
authors.lastname: Costa
authors.forename: Iara F
authors.initials: IF
authors.lastname: Gimenez
authors.forename: Koiti
authors.initials: K
authors.lastname: Araki
authors.forename: Ildemar
authors.initials: I
authors.lastname: Mayer
authors.forename: Fabio Monaro
authors.initials: FM
authors.lastname: Engelmann
authors.forename: Henrique Eisi
authors.initials: HE
authors.lastname: Toma
authors.forename: Ledjane S
authors.initials: LS
authors.lastname: Barreto
mesh_terms: D005453:Fluorescence; D005782:Gels / Q000737:chemistry*; D007700:Kinetics; D036103:Nanotechnology / Q000379:methods*; D009942:Organometallic Compounds / Q000737:chemistry*; D044367:Phase Transition; D011166:Porphyrins / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013057:Spectrum Analysis; D013194:Staining and Labeling; D013696:Temperature
chemical_list: D005782:Gels; D009942:Organometallic Compounds; D011166:Porphyrins; C099070:tetraruthenated porphyrin; D012822:Silicon Dioxide