Phosphorescent Iridium(III) Complexes with Acyclic Diaminocarbene Ligands as Chemosensors for Mercury

Abstract

A new application for bis­(cyclometalated) iridium­(III) species containing ancillary acyclic diaminocarbene ligands, viz. for sensing of mercury­(II) ions, is disclosed. A family of bis­(cyclometalated) iridium­(III) species supported by both parent isocyanide and acyclic diaminocarbene ligands was prepared, and their electrochemical and photophysical properties were evaluated, revealing efficient blue-green phosphorescence in solution with quantum yields of up to 55%. We uncovered that the photophysical properties of these complexes are dramatically altered by the presence of metal ions and that the complex [Ir­(ppy)2(CN)­{C­(NH2)­(NHC6H4-4-X)}] with an ADC ligand reacts selectively with Hg2+ ions, enabling its use for sensing of mercury­(II) ions in solution. The limit of detection was as low as 2.63 × 10–7 M, and additional mechanistic studies indicated the formation of an unusual dinuclear iridium­(III) cyclometalated intermediate, bridged by a mercury dicyano fragment as a driving force of mercury sensing.

Chemosensors based on N-heterocyclic dyes: advances in sensing highly toxic ions such as CN− and Hg2+

“…Good LOD results have been observed in other fused pyridines, which means that some probes can be applied in real and biological samples. [114][115][116][117][118][119][120][121] 3.4.1. Probes having pyridine.…”

“…28b). 115 Similarly, Eremina et al 116 developed a new application via bis(cyclometalated) iridium(III) species bearing an analyte. For all the complexes, their absorption spectra exhibited a strong band at 340 nm with high molar extinction coefficients (3 ¼ 1.03/7.96 Â 10 4 M À1 cm À1 ) due to the spin-allowed p-p* ligandcentered transitions.…”

Спектрально-люминесцентные свойства циклометаллированных комплексов Pd(II) на основе метилового эфира цинхофена

“…Герцена. Спектры ЯМР 1 H, 13 13 C HMQC, 1 Н- 13 C HMBC и 1 Н- 15 без дополнительной очистки. Все растворители очищали с использованием стандартных методик [17].…”

“…Однако фотофизические характеристики подробно исследованы только для октаэдрических Ir(III), Rh(III) и плоскоквадратного Pt(II) комплексов [8,[10][11][12]. Металлированные цинхофены -это часть большого сообщества циклометаллированных комплексов, интенсивная люминесценция которых в сочетании с особенностью электронного строения привлекает внимание исследователей при разработке светоиндуцирующих устройств (типа OLED) [13], сенсоров на молекулярный кислород [14], ионы тяжелых элементов [15], рН, люминесцентные маркеры биомолекул [11], а также применяются для фотодинамической терапии [16].…”

Tuning the luminescence of transition metal complexes with acyclic diaminocarbene ligands

“…26,27 and ADCs. 28,29 The prevailing part of examples disclose the photophysical properties of metal-NHC species (for the reviews on the topic see Refs. [30][31][32][33] ; for the recent manuscripts see Refs.…”