A colorimetric phosphorescent chemosensor Ir(pqz)2(cdc) showed satisfactory selective, sensitive, naked eye detection and fluorescence change response to Hg²⁺ in MeCN.

Different types of fluorescent probes for Hg²⁺ based on the 5-thiophen-2-yl-benzothiazole derivatives (TBT, CTBT, DTBT and NTBT) were realized by changing the subsituents, including the fluorescence quenching probe, the fluorescence enhancement probe and the ratiometric fluorescent probe.

A highly selective colorimetric and fluorescent sensor for Hg²⁺, TPS (TPS = 2-(4-(diphenyl-amino)phenyl)quinazoline-4(3H)-thione), based on a 2-substituted quinazoline-4(3H)-thione derivative, was designed and characterized in this paper. TPS displays relatively strong fluorescence centered at about 468 nm. When mixing with Hg²⁺, TPS interacts with Hg²⁺ in a 2 : 1(TPS-Hg²⁺) stoichiometry via a coordination bond interaction between the sulfur atom and Hg²⁺ with an association constant of 4.17 × 10⁸ M⁻² (R² = 0.96). Upon addition of Hg²⁺, TPS showed a remarkable decrease in fluorescence spectra (468 nm) with a clear color change from yellow to red, so TPS could serve as a naked-eye sensor for Hg²⁺. The sensor allow determination of Hg²⁺ in the working range 2.0 μM–12.0 μM with a detection limit of 1.5 μM. Upon addition of KI to the solution of TPS-Hg²⁺ species, the spectra can be restored to the original spectrum in both absorption and fluorescence and indicates that this sensor could be reused. The sensor exhibited excellent reproducibility, reversibility and selectivity.

A series of steric phenylpyridazine based homoleptic iridium(III) complexes (1–3) have been synthesized with novel one-pot methods. Single X-ray structural analyses are conducted on complexes 1 and 2 to reveal their coordination arrangement. These complexes exhibit a very strong green phosphorescence emission with high quantum yields of over 64%. The relationship between photophysical properties and the substituent nature of the complexes is discussed by density functional theory (DFT) and time-dependent DFT. Self-quenching is significantly reduced for these complexes in solid even at very high concentrations because the sterically hindered bicyclo [2.2.2] oct-2-ene and m-substituted CF₃ spacers in the phosphor molecules lead to minimum bimolecular interactions. Accordingly, the electroluminescence device based on complex 3 exhibits a maximum luminous efficiency of 64.1 cd A⁻¹ with a high EQE of 25.2% at a high doping concentration of 15 wt%. Meanwhile, when neat 3 was adopted as the emitting layer, the non-doped green device gives a state-of-the-art EQE as high as 15.2% (40.1 cd A⁻¹) along with CIE coordinates of (0.346, 0.599).

An OLED based on complex 1 shows promising efficiencies of 18.2%, 58.5 cd A⁻¹ and 45.9 lm W⁻¹ which are 40% higher than those of PO-01.