INO
CNR
vai_a_storia   vai_a_organizzazione   vai_a_sedi   vai_a_personale   Area Riservata
    English English Version  
 
 

Relaxation properties of porphyrin, diprotonated porphyrin, and isoelectronic tetraoxaporphyrin dication in the S-2 state

  Articoli su Riviste JCR/ISI  (anno 2007)

Autori:  Marcelli A., Foggi P., Moroni L., Gellini C., Salvi PR., Badovinac I

Affiliazione Autori:  Laboratorio Europeo di Spettroscopie non Lineari (LENS), Universita´ di Firenze, Via N. Carrara 1, 50019 Sesto Fiorentino, Firenze, Italy; Dipartimento di Chimica, Universita´ di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy; Dipartimento di Chimica, Universita´ di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy; Faculty of Arts and Sciences, Physics Department, University of Rijeka, Omladinska 14, Rijeka, Croatia; CNR - Istituto Nazionale di Ottica Applicata, Largo E. Fermi 6, 50125 Firenze, Italy

Riassunto:  The fluorescence spectra of unsubstituted porphyrin (H2P), diprotonated porphyrin (H4P2+), and isoelectronic tetraoxaporphyrin dication (TOxP(2+)) have been measured in solution at room temperature. The S-2 -> S-0 fluorescence has been observed, much more intense for TOxP(2+) than for H4P2+ and H2P. In the TOxP(2+) case, the S-2 -> S-0 fluorescence spectrum is remarkably sharp and shows an excellent mirror symmetry with respect to S-0 -> S-2 absorption. On the contrary, the spectra of H4P2+ and H2P are shifted and more extended with respect to the absorption counterparts. The differences have been attributed primarily to the change of the equilibrium geometry upon excitation, larger in H2P and H4P2+ than in TOxP(2+) and in the case of H4P2+ to the nonplanar conformation of the macrocycle. Also the S-1 -> S-0 spectra of H2P, H4P2+, and TOxP(2+) have been measured and more qualitatively discussed. The S-1 and S-2 fluorescence decays have been observed for H4P2+ and TOxP(2+) exciting with ultrashort pulses. The S-2 lifetime of TOxP(2+) is of the order of the temporal resolution of our experimental apparatus, whereas that of H4P2+ is shorter. The S-2 -> S-0 quantum yield of TOxP(2+) has been estimated to be 0.035, similar to 3 orders of magnitude higher than that of H4P2+. It is proposed on the basis of ab initio model calculations that excited states of the H4P2+(CF3COO-)(2) complex with charge-transfer character are responsible of the increased extension of the S-2 -> S-0 spectrum with respect to that of H2P.

Rivista/Giornale:  JOURNAL OF PHYSICAL CHEMISTRY A
Volume n.:  111 (12)      Pagine da: 2276  a: 2282
DOI: 10.1021/jp0686846

*Impact Factor della Rivista: (2007) 2.918   *Citazioni: 25
data tratti da "WEB OF SCIENCE" (marchio registrato di Thomson Reuters) ed aggiornati a:  19/05/2019

Riferimenti visionabili in IsiWeb of Knowledge: (solo per sottoscrittori)
Per visualizzare la scheda dell'articolo su IsiWeb: Clicca qui
Per visualizzare la scheda delle Citazioni dell'articolo su IsiWeb: Clicca qui

INO © Istituto Nazionale di Ottica - Largo Fermi 6, 50125 Firenze | Tel. 05523081 Fax 0552337755 - P.IVA 02118311006     P.E.C.    Info