title: Synthesis and solvent-dependent photochromic reactions of porphyrin-spiropyran hybrid compounds.
abstract: Porphyrin(Por)-spiropyran(SP) hybrid compounds, including Por-SP dyad, Por-SP2 triad, and Por-SP4 pentad, were prepared and characterized by (1)H NMR, MALDI-TOF MS and UV-Vis spectroscopies. Upon 350 nm UV irradiation of Por-SPn (n=1, 2, 4) in dichloromethane, unusual red-shifted absorption spectra were observed with the colour change from pink into green. Probably due to the protonation of core nitrogens in porphyrin ring, their absorption maxima in dichloromethane were shifted from 418 (Soret band), 515, 550, 590, 645 (four Q bands) nm into 450 and 665 nm. Also, fluorescence maxima were also shifted from 650 and 715 nm to 692 nm. In the other hands, upon irradiation with 350nm UV light in THF, the colour changed from pink into violet and absorption band at 590 nm increased and the fluorescence spectra showed the decrease of 650 and 715 nm bands and increase of 600-640 nm band, due to the normal ring-opening reaction of spiropyran moiety into merocyanine. In the dark, original absorption and fluorescence spectra were recovered very slowly in dichloromethane, but quickly in THF. The reversible photochromic reactions of Por-SPn (n=1, 2, 4) in dichloromethane and THF were investigated by observing absorption and fluorescence spectral changes during UV irradiation or standing in the dark.
authors.affiliation: Department of Chemistry, Sunchon National University, Suncheon, Jeonnam 540-950, Republic of Korea.
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Hur
authors.forename: Tae Jong
authors.initials: TJ
authors.lastname: Park
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Shin
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D005453:Fluorescence; D007211:Indoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008752:Methylene Chloride / Q000737:chemistry; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry*; D055668:Photochemical Processes; D011166:Porphyrins / Q000737:chemistry*; D011522:Protons; D012997:Solvents / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
chemical_list: D001578:Benzopyrans; D056831:Coordination Complexes; D007211:Indoles; D009574:Nitro Compounds; D011166:Porphyrins; D011522:Protons; D012997:Solvents; C088184:spiropyran; D008752:Methylene Chloride
keywords: Absorption; Fluorescence; Photochromic reaction; Porphyrin; Spiropyran