0000000000447683
AUTHOR
João Pina
Energetics and Dynamics of Naphthalene Polyaminic Derivatives. Influence of Structural Design in the Balance Static vs Dynamic Excimer Formation
Two new fluorescent macrocyclic structures bearing two naphthalene (Np) units at both ends of a cyclic polyaminic chain were investigated with potentiometric, fluorescence (steady-state and time-resolved) and laser flash photolysis techniques. The fluorescence emission studies show the presence of an excimer species whose formation depends on the protonation state of the polyamine chains implying the existence of a bending movement (occurring in both the ground and in the first singlet excited state), which allows the two naphthalene units to approach and interact. For comparison purposes, one bis-chromophoric compound containing a rigid chain (piperazine unit) was also investigated. Its em…
Room-Temperature Phosphorescence and Efficient Singlet Oxygen Production by Cyclometalated Pt(II) Complexes with Aromatic Alkynyl Ligands
The synthesis of five novel cyclometalated platinum(II) compounds containing five different alkynyl-chromophores was achieved by the reaction of the previously synthesized Pt–Cl cyclometalated compound (1) with the corresponding RC≡CH by a Sonogashira reaction. It was observed that the spectral and photophysical characteristics of the cyclometalated platinum(II) complexes (Pt–Ar) are essentially associated with the platinum-cyclometalated unit. Room-temperature emission of the Pt–Ar complexes was attributed to phosphorescence in agreement with DFT calculations. Broad nanosecond (ns)-transient absorption spectra were observed with decays approximately identical to those obtained from the emi…
Synthesis and photophysical properties of dansyl-based polyamine ligands and their Zn(II) complexes
The synthesis, potentiometric studies and photophysical properties of two new polyamine ligands (L1 and L2) possessing the dansyl chromophore were studied in aqueous 0.15 M NaCl. The compounds show the absorption and emissions bands characteristic of the dansylamide fluorophore and both present intramolecular excited state proton transfer at intermediate pH ranges. One of the ligands (L2) strongly coordinates Zn(II) leading to fluorescence quenching. A model compound (L3) of the dansyl moiety was also investigated. http://www.sciencedirect.com/science/article/B6TG5-4MB4DV1-2/1/45cafbcee9a8df7daddd765512437ca3
Spectroscopy and Coordination Chemistry of a New Bisnaphthalene−Bisphenanthroline Ligand Displaying a Sensing Ability for Metal Cations
A new fluorescent macrocyclic structure (L1) bearing two naphthalene units at both ends of a cyclic polyaminic chain containing two phenanthroline units was investigated with potentiometric and fluorescence (steady-state and time-resolved) techniques. The fluorescence emission spectra show the simultaneous presence of three bands: a short wavelength emission band (naphthalene monomer), a middle emission band (phenanthroline emission), and a long-wavelength band. All three bands were found to be dependent on the protonation state of the macrocyclic unit (including the polyaminic and phenanthroline structures). The existence of the long-wavelength emission band is discussed and is shown to im…
A New ZnIITweezer Pyridine-Naphthalene System - An Off-On-Off System Working in a Biological pH Window
Their basic idea consisted of the connec-tion of an amine to a fluorophoric anthracene unit on oneside and to a pyridine moiety on the other. At acidic pHvalues the amino and the pyridine groups are protonatedand a photoinduced electron transfer (PET) occurs fromthe π-π* excited state of the anthracene to the protonatedpyridinium unit, leading to quenching of the fluorescence.However, at high pH values, where the amino group is notprotonated, PET alternatively takes place from the aminelone pair to the same excited state of the fluorophore, yield-ing the same inhibitory effect on the fluorescence. Betweenthese two pH values, there is a pH window where PET doesnot take place and fluorescence…
CCDC 1970146: Experimental Crystal Structure Determination
Related Article: Ariadna Lázaro, Carla Cunha, Ramon Bosque, João Pina, Jas S. Ward, Khai-Nghi Truong, Kari Rissanen, João Carlos Lima, Margarita Crespo, J. Sérgio Seixas de Melo, Laura Rodríguez|2020|Inorg.Chem.|59|8220|doi:10.1021/acs.inorgchem.0c00577
CCDC 1970147: Experimental Crystal Structure Determination
Related Article: Ariadna Lázaro, Carla Cunha, Ramon Bosque, João Pina, Jas S. Ward, Khai-Nghi Truong, Kari Rissanen, João Carlos Lima, Margarita Crespo, J. Sérgio Seixas de Melo, Laura Rodríguez|2020|Inorg.Chem.|59|8220|doi:10.1021/acs.inorgchem.0c00577
CCDC 1970145: Experimental Crystal Structure Determination
Related Article: Ariadna Lázaro, Carla Cunha, Ramon Bosque, João Pina, Jas S. Ward, Khai-Nghi Truong, Kari Rissanen, João Carlos Lima, Margarita Crespo, J. Sérgio Seixas de Melo, Laura Rodríguez|2020|Inorg.Chem.|59|8220|doi:10.1021/acs.inorgchem.0c00577