Implicit Solvation Models: Equilibria, Structure, Spectra, and Dynamics.

Graphene- and CNTs-based carbocatalysts in persulfates activation: Material design and catalytic mechanisms

General Principles and Strategies for Salting-Out Informed by the Hofmeister Series

Binding benzene: A novel blue luminescent star-shaped ZnII complex has been found to be able to detect benzene selectively by fluorescent quenching. This is attributed to the compoundapos;s high affinity to benzene, as demonstrated in the crystal structure (see picture; yellow: benzene, red: zinc).

A Blue Luminescent Star‐Shaped ZnII Complex that Can Detect Benzene

Carbon dots (CDs) have emerged as novel fluorescent probes due to their remarkable optical properties; however, red emission is still rare, has a relatively low efficiency, and its mechanism remains ambiguous. Herein, relatively efficient red-emission CDs based on p-phenylenediamine were prepared through various solvothermal means, where the highest quantum yield approached 41.1% in n-amyl alcohol, which was the most efficient quantum yield reported to date. Various structural characterizations were performed and confirmed that the red emission originated from the molecular states consisting of a nitrogen-containing organic fluorophore. The CDs were dispersed in different organic solvents and showed tunable emission, evolving from green to orange-red in aprotic solvents and a red emission in protic solvents. Further solvent correlation studies indicated that the hydrogen bond effect between the CDs and solvents was the main mechanism leading to the spectral shift. Accordingly, solid-state luminescent CDs–polymers were fabricated, which also demonstrated continuously tunable emission properties. This work opens a new window for recognizing the generation of tunable and red-emission CDs.

A novel mechanism for red emission carbon dots: hydrogen bond dominated molecular states emission

The absorption and fluorescence spectra of a set of dehydro and fully aromatic β-carboline (9H-pyrido[3,4-b]indole) derivatives have been investigated in aqueous solutions of varying acidity. Within the pH-range, cationic (nitrogen protonation) and neutral species are evidenced from both absorption and fluorescence spectra. Additional zwitterionic species can also be detected from the fluorescence spectra. In highly basic media, outside the pH-range, anionic species (pyrrolic nitrogen deprotonation) are formed. Ground state ionization constants for the different acid–base equilibria involving these species have been determined spectrophotometrically at 25 °C. Lowest excited singlet state pKas have been estimated from the Forster–Weller cycle. The influence of structural variations on the spectra and on the acid–base properties of these compounds is discussed.

Acid–base and spectral properties of β-carbolines. Part 2. Dehydro and fully aromatic β-carbolines

To study the ground and singlet excited state hydrogen bonding donor/acceptor properties of the betacarboline
 ring, 9H-pyrido[3,4-b]indole, we have carried out a spectroscopic study of the interactions of harmane, 1-methylbetacarboline, HN, and its N9-methyl derivative, MHN, with different hydrogen bonding acceptor/donor
 molecules in the non-polar solvent cyclohexane. UV–visible, steady-state and time-resolved fluorescence
 measurements show that HN and MHN form fluorescent 1:1 ground state hydrogen bonded pyridinic complexes
 with the hydrogen bond donors tert-butanol, 2-chloroethanol and hexafluoropropan-2-ol. At high
 concentrations, the strongest hydrogen bond donors chloroethanol and hexafluoropropan-2-ol form additional
 proton transfer ground-state 1:2 hydrogen-bonded complexes which, upon photoexcitation, give phototautomers
 of zwitterionic structures. The aromatic donor phenol also forms hydrogen bonded pyridinic
 complexes with HN, but zwitterionic species are not observed. Furthermore, the hydrogen bonding HN–phenol
 interaction quenches the HN fluorescence. On the other hand, the interactions of HN with the
 proton acceptors tetrahydrofuran, N,N-dimethylformamide and hexamethylphosphoramide also give fluorescent
 1:1 hydrogen bonded pyrrolic complexes which do not form phototautomeric zwitterions. These results conclusively
 show that the formation of zwitterionic phototautomers involves the initial attack of a hydrogen bonding
 donor molecule on the pyridinic
 nitrogen atom of
 the betacarboline and
 the formation of a 1:2 proton transfer complex.

Ground and singlet excited state hydrogen bonding interactions of betacarbolines

The acid-base properties of pyrrole and its benzologs indole and carbazole: a reexamination from the excess acidity method

A fluorescence study of the molecular interactions of harmane with the nucleobases, their nucleosides and mononucleotides

The kinetics of exciplex formation of N9-methyl-1-methyl-9H-pyrido[3,4-b]indole, MHN, in the presence of the proton donor hexafluoro2-propanol, HFIP, in cyclohexane has been studied by UV-vis, stea...

María A. Muñoz

Papers

Acid–base and spectral properties of β-carbolines. Part 2. Dehydro and fully aromatic β-carbolines

Ground and singlet excited state hydrogen bonding interactions of betacarbolines

The acid-base properties of pyrrole and its benzologs indole and carbazole: a reexamination from the excess acidity method

A fluorescence study of the molecular interactions of harmane with the nucleobases, their nucleosides and mononucleotides

Kinetic Study of Hydrogen Bonded Exciplex Formation of N9-methyl Harmane†