Chemical sensors based on π-conjugated organic molecules and gold nanoparticles

Highly Selective and Ultrasensitive Turn-on Luminescence Chemosensor for Mercury (II) Determination Based on the Rhodamine 6G Derivative FC1 and Au Nanoparticles

A method for the detection and quantitation of Hg²⁺ in aqueous samples by fluorescence spectroscopy is presented. It consists of a turn-on sensor developed by coupling Gold nanoparticles (AuNPs) with the rhodamine 6G derivative FC1, in which the response is generated by a mercury-induced ring-opening reaction. The AuNPs were included in order to improve the sensitivity of the method towards the analyte, maintaining its high selectivity. The method was validated in terms of linearity, precision and accuracy, and applied to the quantitation of Hg²⁺ in Milli-Q and tap water with and without spiked analyte. The limit of detection and quantitation were 0.15 μg·L⁻¹ and 0.43 μg·L⁻¹, respectively, constituting a substantial improvement of sensitivity in comparison with the previously reported detection of Hg²⁺ with free FC1.

Lanthanide coordination polymer probe for time-gated luminescence sensing of pH in undiluted human serum

Lanthanide coordination polymers (LCPs) have emerged as fascinating materials because of their specific structure and properties. In this work, utilizing hydrosoluble biomolecule of guanosine-5'-monophosphate (GMP) as bridging linker, lanthanide terbium ions (Tb³⁺) as metal nodes, and silver ions (Ag⁺) as sensitizers, we synthesized a pH responsive luminescent lanthanide CP probe of Tb/GMP/Ag. The probe possesses high luminescence due to the sensitization of Ag⁺; While in alkaline solutions, Ag⁺ in Tb/GMP/Ag immediately binds to OH^-, forming Ag₂O precipitation and resulting in a distinct fluorescence quenching of Tb/GMP/Ag. This probe displays high selectivity for OH^- and a broader pH detection range of 7.5-13.0. In addition, based on the high anti-interference ability in serum, we applied Tb/GMP/Ag to measure pH in undiluted human serum samples, yielding satisfactory results.

Design and electronic structure of new styryl dye bases: steady-state and time-resolved spectroscopic studies

A comprehensive investigation of the electronic structure and fast relaxation processes in the excited states of new styryl base-type derivatives was performed using steady-state, pico-, and femtosecond time-resolved spectroscopic techniques. Linear photophysical parameters of new compounds, including steady-state absorption, fluorescence, and excitation anisotropy spectra, were obtained in a number of organic solvents at room temperature. A detailed analysis of the fluorescence lifetimes and ultrafast relaxation processes in the electronically excited state of the styryl bases revealed an important role of solvate dynamics and donor-acceptor strength of the molecular structures in the formation of their excited state absorption spectra. Experimental data were in good agreement with quantum chemical calculations at the time dependent density functional theory level, combined with a polarizable continuum model.

Laser spectroscopy for atmospheric and environmental sensing

Lasers and laser spectroscopic techniques have been extensively used in several applications since their advent, and the subject has been reviewed extensively in the last several decades. This review is focused on three areas of laser spectroscopic applications in atmospheric and environmental sensing; namely laser-induced fluorescence (LIF), cavity ring-down spectroscopy (CRDS), and photoluminescence (PL) techniques used in the detection of solids, liquids, aerosols, trace gases, and volatile organic compounds (VOCs).