Rapid and Highly Sensitive Dual-Channel Detection of Cyanide by Bis-heteroleptic Ruthenium(II) Complexes

Abstract

Two new ruthenium complexes [Ru(bipy)(2)(PDA)](2+) (1) and [Ru(phen)(2)(PDA)](2+) (2) (PDA = 1,10-phenanthroline-4,7-dicarboxaldehyde) have been synthesized to detect cyanide based on the well-known formation of cyanohydrins. Both 1[PF(6)](2) and 2[PF(6)](2) were fully characterized by various spectroscopic techniques and their solid state structures determined by single-crystal X-ray diffraction. Their anion binding properties in pure and aqueous acetonitrile were thoroughly examined using two different channels, i.e., UV-vis absorption and photoluminescence (PL). After addition of only 2 equiv of CN(-), the PL intensity of 1[PF(6)](2) and 2[PF(6)](2) was enhanced ∼55-fold within 15 s along with a diagnostic blue shift of the emission by more than 100 nm. PL titrations of 1[PF(6)](2) and 2[PF(6)](2) with CN(-) in CH(3)CN furnished the very high overall cyanohydrin formation constants log β([CN(-)]) = 15.36 ± 0.44 (β([CN(-)]) = 2.3 × 10(15) M(-2)) and log β([CN(-)]) = 16.37 ± 0.53 (β([CN(-)]) = 2.3 × 10(16) M(-2)), respectively. For both probes, the second constant, K(2), is about 57-84 times less than K(1), suggesting that the cyanohydrin reaction is stepwise. The stepwise mechanism is further supported by results of a (1)H NMR titration of 2[PF(6)](2) with CN(-). The high selectivity of 2[PF(6)](2) for CN(-) was established by PL in the presence of other competing anions. Furthermore, the color change from orange-red to yellow and the appearance of a orange luminescence, which can be observed by the naked eye, provides a simple real-time method for cyanide detection. Finally, theoretical calculations were carried out to elucidate the details of the electronic structure and transitions involved in the ruthenium probes and their cyanide adducts.

Excited State Tuning of Bis(tridentate) Ruthenium(II) Polypyridine Chromophores by Push–Pull Effects and Bite Angle Optimization: A Comprehensive Experimental and Theoretical Study

“…Polypyridine complexes of ruthenium(II) have attracted great interest due to their outstanding and tunable photophysical and electrochemical properties combined with high thermal and chemical robustness. [1] They are used as light harvesters in dye-sensitized solar cells, [2][3][4] luminescent emitters in light-emitting electrochemical cells, [5][6][7] possible anticancer and imaging agents in phototherapy, [8][9][10] sensors for ions [11][12][13][14][15][16] and small molecules, [17,18] photocatalysts for water splitting, [19,20] hydrogen production, [21][22][23][24] CO 2 reduction, [21,23,25] and many other chemical reactions, [23,[26][27][28][29] components in mixed valence systems, [30][31][32][33][34][35] light upconversion systems [36][37][38][39] and molecular memory devices. [40][41][42] The most prominent ruthenium(II) polypyridine complexes are [RuA C H T U N...…”

Synthesis and characterization of ruthenium(II) complexes incorporating 4′-phenyl-terpyridine and triphenylphosphine

“…They are used as light harvesters in dye-sensitized solar cells [2][3][4], luminescent emitters in light-emitting electrochemical cells [5][6][7], potential anticancer and imaging agents in phototherapy [8][9][10], sensors for ions [11][12][13][14][15][16] and small molecules [17,18], photocatalysts for water splitting [19,20], hydrogen production [21][22][23][24], CO 2 reduction [21,23,25], and many other chemical reactions [23,[26][27][28][29], components in mixed valence systems [30][31][32][33][34][35], light upconversion systems [36][37][38][39] and molecular memory devices [40][41][42].…”

Dual-channel optical sensing platform for detection of diminazene aceturate based on thioglycolic acid-wrapped cadmium telluride/cadmium sulfide quantum dots

“…Multidimensional sensing devices such as dual- [14][15][16], triple- [17] and quadruple-channel [18] sensing have drawn significant attention, on account of they can offer more than one transduction channel and thereby enhance the accuracy and/or diversity. Nevertheless, most of these are based on the preparation of optical probes for target guest.…”