Ru(ii) and Os(ii) mixed-chelates derived from imidazole-4,5-dicarboxylic acid and 2,2′-bipyridine as colorimetric sensors for anions: synthesis, characterization and binding studies

Abstract

Mixed-ligand monometallic ruthenium(II) and osmium(II) complexes of composition [(bipy)(2)M(H(2)Imdc)](ClO(4)), where H(3)Imdc = imidazole-4,5-dicarboxylic acid and bipy = 2,2'-bipyridine, have been synthesized and characterized using standard analytical and spectroscopic techniques. The X-ray crystal structures of the ruthenium(II) complexes, [(bipy)(2)Ru(H(2)Imdc)](ClO(4)) (1) and its corresponding N-H deprotonated form [(bipy)(2)Ru(HImdc)] (3) have been determined. Compound 1 crystallizes in monoclinic form with space group P2(1)/c while 3 is obtained in triclinic form with the space group P1. The anion binding properties of the complexes 1 and 2 have been thoroughly investigated in acetonitrile solution using absorption, emission, and (1)H NMR spectral measurements. Both of the metalloreceptors act as sensors for F(-), AcO(-) and H(2)PO(4)(-) anions. Although at relatively lower concentration of anions, the 1 : 1 H-bonded adduct is formed, in the presence of excess of anions, deprotonation of the imidazole N-H fragment occurs and is accompanied by distinct change of colour. Cyclic voltammetry (CV) measurements carried out in acetonitrile have provided evidence in favour of anion-dependent electrochemical responses of 1 and 2 with F(-) and AcO(-) ions.

A Review on 4, 5-Imidazoledicarboxylic Acid: Their Chemistry and Coordination Potentials

“…The rational design and synthesis of novel Supramolecular complexes has recently attracted much attention, because of their intriguing structures and their various potential applications in catalysis, magnetism, photoluminescence, adsorption, gas storage, biological application, pharmaceutical activity, drugs, etc. [16,14,20]. The discrete metal-organic polygons and polyhedral have been widely studied and continue to be one of the most interesting.…”

“…These strategies undoubtedly help to shed light on the prediction, design, and synthesis of the target complexes. For example, imidazole-4,5-dicarboxylic acid (H 3 IDC), which can be partially or fully deprotonated to generate H 2 IDC 1-, HIDC 2-, and IDC 3-anions at different pH values, coordinating with metal ions to form different Metal-Organic Frameworks with interesting 0-D, 1-D, 2-D, and 3-D topologies [16,18,20]. Over the past few years, extensive investigation has focused on the construction of coordination polymers using 4,5-imidazoledicarboxylic acid as bridges of interest for the following reasons: (1) they are especially good multidentate N-or O-donors with various coordination modes to metal ions and the ability to act as H-bond acceptors and donors to assemble various supramolecular structures; (2) they can be partly or fully deprotonated dependent on the pH, providing various acid-base type coordination modes; (3) the two nitrogen's in the imidazole ring can orient the coordination, consistent with Si-O-Si bond angles in zeolites or M-IM-M bond angle in zeolitic imidazolate frameworks (ZIF) [16,[18][19][20].…”

“…Therefore, the aim of this review paper was to contribute and initiate the researcher towards the new 4, 5-imidazoledicarboxylic acids based metal complex synthesis and characterization. Supramolecular chemistry and metal-organic polymeric networks via crystals engineering have produced many new complexes with unique structures [14][15][16][17][18][19][20][21]. The rational design and synthesis of novel Supramolecular complexes has recently attracted much attention, because of their intriguing structures and their various potential applications in catalysis, magnetism, photoluminescence, adsorption, gas storage, biological application, pharmaceutical activity, drugs, etc.…”

“…The structural modify of metal-organic frameworks are closely related to the geometry around the metal centers and organic ligand properties (Figures 5 and 6). The types of organic ligands containing N and O-donors offer great potential for fine control over the coordination architectures of metal-organic frameworks (MOFs)due to their flexible coordination modes [10][11][12][13][14][15][16][17][18]20]. The selfassembly process of coordination polymers is frequently influenced by various factors such as medium, pH value of solution, temperature, the nature of metal ions, coordination arrangement, stereochemistry, and number of coordination donors provided by organic ligands [17,18].…”

“…These transition metal ions usually form complexes with a well defined number of ligands [10][11][12][13][14][15][16][17][18][19][20] 2 ] pillars, was synthesized hydrothermally and characterized by IR spectroscopy, elemental analysis, TGA, and magnetic measurements. It is the first example of a 3D framework containing 4, 5-imidazoledicarboxylate in the family of manganese complexes.…”