Proton‐Dependent Switching of a Novel Amino Chlorin Derivative as a Fluorescent Probe and Photosensitizer for Acidic Media

Abstract

A novel chlorin derivative (TPCF -NMe ) has been synthesized as a syn adduct of a pyrrolidine-fused chlorin bearing a C-linked N,N-dimethylaminophenyl residue. The absorption spectrum of TPCF -NMe is essentially identical to that of TPCF in N,N-dimethylformamide, indicating a very weak interaction between the chlorin macrocycle and the amine group in the ground state. However, the fluorescence emission of the chlorin moiety in TPCF -NMe is effectively quenched by the attached amine unit. Moreover, TPCF -NMe is unable to attain a triplet excited state or to photosensitize singlet molecular oxygen. Spectroscopic and redox properties indicate that intramolecular photoinduced electron transfer can take place from the N,N-dimethylaminophenyl group to the chlorin macrocycle. Thus, in an acid medium, protonation of the amino group leads to a considerable increase in the fluorescence emission, triplet excited-state formation, and singlet molecular oxygen production. Photodynamic inactivation of Escherichia coli sensitized by TPCF -NMe is negligible at neutral pH. However, this chlorin becomes highly effective in inactivating E. coli cells under acidic conditions. Therefore, these results indicate that TPCF -NMe is an interesting molecular structure, in which protonation of the amino group can be used as an off/on molecular switch activating red fluorescence emission and photodynamic activity capable of eradicating bacteria.

Photoactive antimicrobial coating based on a PEDOT-fullerene C60 polymeric dyad

“…To that end, decomposition of DMA photoinduced by PEDOT-C 60 was used to monitor the O 2 ( 1 D g ) generation. 26,65 In this method, DMA quenches O 2 ( 1 D g ) by a rapid chemical reaction, producing the endoperoxide derivative. 66 The photodecomposition reaction was monitored by UV-visible spectroscopy following the decrease of the DMA absorption band at 379 nm.…”

Antimicrobial Photodynamic Polymeric Films Bearing Biscarbazol Triphenylamine End-Capped Dendrimeric Zn(II) Porphyrin

“…It can be note that Q(0-0) band is a smaller transition than Q(0-1), which is distinctive of pentafluorophenyl porphyrin derivatives. [45][46][47] Moreover, the energy levels values of the singlet excited state (E s ) were estimated for both photosensitizers (Table 1). E s values are comparable to those previously reported for zinc(II) porphyrins.…”

BOPHY‐Fullerene C60 Dyad as a Photosensitizer for Antimicrobial Photodynamic Therapy

“…The latter is formed from the Strecker degradation of N-methylglycine. [39] The molecular structure of dyad BP-C 60 was fully confirmed and elucidated by NMR and high-resolution mass spectroscopy (HRMS; Figures S1-S8 in the Supporting Information). A close analysis of the 1 H NMR spectrum revealed a ~1 : 1 mixture of isomers as most of the expected signals were duplicated with variable Δδ values.…”

“…[37] Besides, N-methylfulleropyrrolidine (P-C 60 ) was also synthesized and used as a reference system. Based on previous reports, [38,39] fullerene C 60 and N-methylglycine were refluxed in 1,2-dichlorobenzene (o-DCB), to cleanly afford 30 % of the [6,6]bridged cycloadduct P-C 60 (Scheme 1). In this Prato cycloaddition, the azomethine ylide is generated in situ from Nmethylglycine and formaldehyde.…”