Colorimetric and luminescent bifunctional Ru(ii) complexes for rapid and highly sensitive recognition of cyanide

Abstract

Four ruthenium(II) complexes, [Ru(bpy)2L1](PF6)2, [Ru(bpy)2L2](PF6)2, [Ru(dmb)2L1](PF6)2, and [Ru(dmb)2L2](PF6)2, where bpy = 2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, L1 = 4-methyl-2,2'-bipyridine-4'-carboxaldehyde, and L2 = 4,4'-diformyl-2,2'-bipyridine, have been characterized for sensing cyanide based on the well-known formation of cyanohydrins. The structure of [Ru(dmb)2L2](PF6)2 is also determined by single crystal X-ray diffraction. Their cyanide anion binding properties in pure and aqueous acetonitrile solution were thoroughly examined by UV-Vis absorption and photoluminescence (PL) spectroscopy. Upon the addition of cyanide to the solution of ruthenium(II) complexes at 298 K, a color change from orange to yellow and a luminescent variation from dark red to red-orange can be observed by the naked eye. The large blue shift of the absorption and emission spectra and significant enhancement of the emission intensity upon the addition of cyanide could be attributed to the formation of a cyanohydrin group by the selective reaction of the aldehyde group of the ruthenium(II) complexes with cyanide. Importantly, these kinds of ruthenium(II) complexes show a unique recognition of cyanide ions over other anions. The results reveal that this kind of ruthenium(II) complex containing an aldehyde group is an eligible sensor for cyanide anions.

Resonance‐Assisted Hydrogen Bonding as a Driving Force in Synthesis and a Synthon in the Design of Materials

“…Recently, there has been increasing interest in the design of reaction‐based chemosensors for CN − . This approach usually utilizes the nucleophilicity of CN − toward attack at unsaturated double bonds, such as C=C, C=O, and C=N, in the RAHB system, yielding the irreversible formation of chemical bonds that can provide chemodosimetric information and lead to remediation, as well as detection, of CN − . Owing to the RAHB system, the double bond situated ortho to the hydroxy group can undergo nucleophilic attack by CN − .…”

Detection of NaCN in aqueous media using a calixarene-based fluoroionophore containing ruthenium(ii)-bipyridine as the fluorogenic unit

“…[11][12][13][14][15][16][17][18][19] Apart from metal complexes, other chemosensors based on quantum dots, organic dyes and other protic chromophores have also been reported for detection of CN -. [20][21][22][23][24][25] Chromophores containing NH and OH has advantage as it can make strong hydrogen-bonding interaction with the anions.…”

“…When designing molecular sensors for anions, especially for CN À , metal complex based sensors have been extensively used as the positive charge on the metal ion facilitates interaction with negatively charged ions. [11][12][13][14][15][16][17][18][19] Apart from metal complexes, other chemosensors based on quantum dots, organic dyes and other protic chromophores have also been reported for detection of CN À . [20][21][22][23][24][25] Chromophores containing NH and OH are advantageous as they can form strong hydrogen-bonding interactions with the anions.…”

Structure–reactivity correlation in selective colorimetric detection of cyanide in solid, organic and aqueous phases using quinone based chemodosimeters

“…Various colorimetric cyanide chemodosimeters have been demonstrated, in which the sensor molecule contains a reactive subunit and a signaling unit as shown in I (Scheme 1). Generally, the reactive subunit XQY may be CQC, [12][13][14][15] CQN, [16][17][18] CQO 19,20 or NQN. 21,22 In majority of the cases, the color of the parent sensor molecule is due to the occurrence of intra-molecular charge transfer (ICT) transition from a donor moiety to an acceptor moiety, via the p-conjugated reactive subunit, which absorbs in the visible region.…”