Absorption and Fluorescence Emission Investigations on Supramolecular Assemblies of Tetrakis-(4-sulfonatophenyl)porphyrin and Graphene Quantum Dots
Mariachiara Sarà,
Salvatore Vincenzo Giofrè,
Salvatore Abate,
Mariachiara Trapani,
Rosaria Verduci,
Giovanna D’Angelo,
Maria Angela Castriciano,
Andrea Romeo,
Giovanni Neri,
Luigi Monsù Scolaro
Affiliations
Mariachiara Sarà
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Salvatore Vincenzo Giofrè
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Salvatore Abate
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Mariachiara Trapani
CNR—ISMN Istituto per lo Studio dei Materiali Nanostrutturati c/o Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Rosaria Verduci
Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Giovanna D’Angelo
Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Maria Angela Castriciano
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Andrea Romeo
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
Giovanni Neri
Dipartimento di Ingegneria, University of Messina, Contrada di Dio, 98158 Messina, Italy
Luigi Monsù Scolaro
Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, University of Messina, V.le F. Stagno D’Alcontres, 31, 98166 Messina, Italy
The one-pot synthesis of N-doped graphene quantum dots (GQDs), capped with a positively charged polyamine (trien), has been realized through a microwave-assisted pyrolysis on solid L-glutamic acid and trien in equimolar amounts. The resulting positively charged nanoparticles are strongly emissive in aqueous solutions and are stable for months. The interaction with the anionic tetrakis(4-sulphonatophenyl)porphyrin (TPPS4) has been investigated at neutral and mild acidic pH using a combination of UV/vis absorption spectroscopy together with static and time-resolved fluorescence emission. At pH = 7, the experimental evidence points to the formation of a supramolecular adduct mainly stabilized by electrostatic interactions. The fluorescence emission of the porphyrin is substantially quenched while GQDs remain still emissive. On decreasing the pH, protonation of TPPS4 leads to formation of porphyrin J-aggregates through the intermediacy of the charged quantum dots.
