1,3-Diketone Calix[4]arene Derivatives—A New Type of Versatile Ligands for Metal Complexes and Nanoparticles

Abstract

The present review is aimed at highlighting outlooks for cyclophanic 1,3-diketones as a new type of versatile ligands and building blocks of the nanomaterial for sensing and bioimaging. Thus, the main synthetic routes for achieving the structural diversity of cyclophanic 1,3-diketones are discussed. The structural diversity is demonstrated by variation of both cyclophanic backbones (calix[4]arene, calix[4]resorcinarene and thiacalix[4]arene) and embedding of different substituents onto lower or upper macrocyclic rims. The structural features of the cyclophanic 1,3-diketones are correlated with their ability to form lanthanide complexes exhibiting both lanthanide-centered luminescence and magnetic relaxivity parameters convenient for contrast effect in magnetic resonance imaging (MRI). The revealed structure–property relationships and the applicability of facile one-pot transformation of the complexes to hydrophilic nanoparticles demonstrates the advantages of 1,3-diketone calix[4]arene ligands and their complexes in developing of nanomaterials for sensing and bioimaging.

Diverse Coordination Numbers and Geometries in Pyridyl Adducts of Lanthanide(III) Complexes Based on β-Diketonate

“…However, it should be mentioned that incorporating strong chelating polypyridyl ligands into the Ln(III)-tris(βketonato) significantly enhances the emission luminescent properties of the compounds in the visible and NIR regions [25,62]. Recently, it has been demonstrated that incorporation of β-diketonate into calix [4] arene ligand skeletons enhances their corresponding lanthanide-centered luminescence and magnetic relaxivity properties [63,64], which make them suitable candidates, especially Gd(III), in magnetic resonance imaging (MRI) and in developing nanomaterials for sensing and bioimaging [64].…”

Single Excited Dual Band Luminescent Hybrid Carbon Dots-terbium Chelate Nanothermometer

“…As it was previously reported the synthesis of hydrophilic colloids from the terbium complexes with cyclophanic 1,3-diketonates is based on their efficient self-assembly in the synthetic conditions of the solvent-exchange technique. [5][6][7] The [TbL] + complex derives from efficient bis-chelating of Tb 3+ via two diketonate groups of the tetra-1,3-diketone calix [4]arene (Figures 4 a,b). The 1:1 complex is formed in the DMF solutions basified by triethylamine (TEA), which is followed by the sensitization of the Tb 3+ -centered luminescence due to the efficient ligand-to-metal energy transfer.…”

“…As it was previously reported, the basification is aimed at shifting the complex formation equilibrium towards [TbL] + , 7,37 where Tb 3+ ions are bis-chelated with two 1,3-diketonate moieties.…”

“…Combination of oppositely charged luminophoric blocks with different nature within one nanobead is a promising route to enforce or modify their luminescent response in aqueous solutions. Incorporation of the different luminescent blocks into polymeric nanobead has been widely exemplified by different polymeric matrices [1][2][3][4] , including those non-covalently generated from self-aggregation of water soluble polymers [5][6][7] . Polyelectrolytes provide very promising type of water soluble polymers due to the multitude of surface exposed ionic groups providing high affinity to oppositely charged surfaces or counterions [8][9][10] .…”

Single Excited Dual Band Luminescent Hybrid Carbon Dots-Terbium Chelate Nanothermometer

“…A ratiometric approach based on the generation of two emission bands with different sensitivities on specific external stimuli opens great opportunities in the evolution of sensing systems [4,5]. Combining luminophoric blocks with different natures within one nanobead is a promising route to develop ratiometric sensing systems, which has been well exemplified by incorporating different luminescent blocks into polymeric nanobeads [6][7][8][9], including non-covalently self-aggregated water-soluble polymers [10][11][12]. Polyelectrolytes provide a very promising type of water-soluble polymers due to the multitude of surface-exposed ionic groups providing high affinity to oppositely charged surfaces or counter-ions [13][14][15].…”