Design and synthesis of a new terbium complex-based luminescent probe for time-resolved luminescence sensing of zinc ions.

Luminescent probes/chemosensors based on lanthanide complexes have shown great potentials in various bioassays due to their unique long-lived luminescence property for eliminating short-lived autofluorescence with time-resolved detection mode. In this work, we designed and synthesized a new dual-chelating ligand {4'-[N,N-bis(2-picolyl)amino]methylene-2,2':6',2'-terpyridine-6,6'-diyl} bis(methylenenitrilo) tetrakis(acetic acid) (BPTTA), and investigated the performance of its Tb(3+) complex (BPTTA-Tb(3+)) for the time-resolved luminescence sensing of Zn(2+) ions in aqueous media. Weakly luminescent BPTTA-Tb(3+) can rapidly react with Zn(2+) ions to display remarkable luminescence enhancement with high sensitivity and selectivity, and such luminescence response can be realized repeatedly.

Highly sensitive and selective phosphorescent chemosensors for hypochlorous acid based on ruthenium(II) complexes.

Microbicidal activity of hypochlorous acid (HOCl) plays pivotal roles in many biological processes, and suitable methods for the in vivo detection of HOCl are highly desirable. Herein we report the development of two novel ruthenium(II) complex-based phosphorescent chemosensors for HOCl, [Ru(bpy)2(DNCA-bpy)](PF6)2 (bpy: 2,2'-bipyridine; DNCA-bpy: 4-N-(2,4-dinitrophenyl)carboxamide-4'-methyl-2,2'-bipyridine) and [Ru(bpy)2(DNCH-bpy)](PF6)2 (DNCH-bpy: 4-N'-(2,4-dinitrophenyl)carbohydrazide-4'-methyl-2,2'-bipyridine). The two sensors are almost non-luminescent due to the intramolecular photoinduced electron transfer (PET) process from the Ru(II)-bpy moiety to dinitrophenyl group, but specific reaction of the sensors with HOCl in aqueous media can afford a highly luminescent derivative, [Ru(bpy)2(COOH-bpy)](PF6)2 (COOH-bpy: 4-carboxylic acid-4'-methyl-2,2'-bipyridine), accompanied by 190-fold and 1100-fold turn-on luminescence signal enhancement for [Ru(bpy)2(DNCA-bpy)](PF6)2 and [Ru(bpy)2(DNCH-bpy)](PF6)2, respectively.

A cell-membrane-permeable europium complex as an efficient luminescent probe for singlet oxygen.

A unique cell-membrane-permeable europium complex has been developed as a probe for time-gated luminescence detection of singlet oxygen (O). Combined with the time-gated luminescence imaging technique, the probe was successfully used for investigating the time-dependent generation and distribution of O induced by the clinical drugs of photodynamic therapy in cancer cells.

Lanthanide complex-based luminescent probes for highly sensitive time-gated luminescence detection of hypochlorous acid.

Two novel lanthanide complex-based luminescent probes, ANMTTA-Eu(3+) and ANMTTA-Tb(3+) {ANMTTA, [4'-(4-amino-3-nitrophenoxy)methylene-2,2':6',2"-terpyridine-6,6"-diyl] bis(methylenenitrilo) tetrakis(acetic acid)}, have been designed and synthesized for the highly sensitive and selective time-gated luminescence detection of hypochlorous acid (HOCl) in aqueous media. The probes are almost nonluminescent due to the photoinduced electron transfer (PET) process from the 4-amino-3-nitrophenyl moiety to the terpyridine-Ln(3+) moiety, which quenches the lanthanide luminescence effectively. Upon reaction with HOCl, the 4-amino-3-nitrophenyl moiety is rapidly cleaved from the probe complexes, which affords strongly luminescent lanthanide complexes HTTA-Eu(3+) and HTTA-Tb(3+) {HTTA, (4'-hydroxymethyl-2,2':6',2"-terpyridine-6,6"-diyl) bis(methylenenitrilo) tetrakis(acetic acid)}, accompanied by the remarkable luminescence enhancements.

A ratiometric luminescence probe for highly reactive oxygen species based on lanthanide complexes.

Reactive oxygen species (ROS) are important mediators in a variety of pathological events, but the oxidative stress owing to excessive generation of ROS is implicated in many human diseases. In this work, we designed and synthesized a novel dual-functional chelating ligand, [4'-(p-aminophenoxy)methylene-2,2':6',2''-terpyridine-6,6''-diyl]bis(methylenenitrilo)tetrakis(acetic acid) (AMTTA), that can strongly coordinate with both Eu(3+) and Tb(3+) in aqueous solutions for the recognition and time-gated luminescence detection of highly ROS (hROS), hydroxyl radical ((•)OH), and hypochlorite (ClO(-)). The complexes AMTTA-Ln(3+) (Ln = Eu and Tb) are almost nonluminescent because of the photoinduced electron transfer from the electron-rich aminophenyl group to the terpyridine-Ln(3+) moiety but can rapidly react with hROS to afford highly luminescent complexes (4'-hydroxymethyl-2,2':6',2''-terpyridine-6,6''-diyl)bis(methylenenitrilo)tetrakis(acetate)-Ln(3+) (HTTA-Ln(3+)).