Structural regularities and luminescence properties of dimeric europium and terbium carboxylates with 1,10-phenanthroline (C.N.=9)

Role of methylene spacer in the excitation energy transfer in europium 1- and 2- naphthylcarboxylates

“…Each Ln 3 + ion coordinates also cyclic carboxylic group and Phen molecule. The degree of distortion of lanthanide coordination polyhedron taken as distorted threecapped trigonal prism in this compound is more pronounced than for many analogous dimeric europium carboxylates with Phen having Eu 3 + C.N.¼9 [9]. In this compound main distortions of Ln coordination polyhedron display as considerable ( $0.7Å) range in the Ln-O distances related to bridging-cyclic COO À -group.…”

“…The Table 1 Relative integral intensities of electronic transitions in the Eu 3 + luminescence spectra I¼ 5 D 0 -7 F J / 5 D 0 -7 F 1 , total integral intensity SI at 77 K and lifetimes t obs of 5 D 0 state. shift of Ln atom from the centre of its coordination polyhedron is 0.15Å, the rotation angle between the bases of trigonal prism is 13.11, and torsion and bending angles between ''pyridine'' rings in Phen are 8.61 and 4.21, respectively [9,11]. The main changes in the structure of Ln coordination polyhedron and in the charge distribution in the nearest surroundings of Ln 3 + ion in dimeric carboxylates with Phen or 2,2 0 -bipyridine (Bpy) of the kind are conditioned by high ''sensitivity'' of bonding of the bridging-cyclic carboxylic group to the type and size of carboxylate ligand [9,12].…”

“…shift of Ln atom from the centre of its coordination polyhedron is 0.15Å, the rotation angle between the bases of trigonal prism is 13.11, and torsion and bending angles between ''pyridine'' rings in Phen are 8.61 and 4.21, respectively [9,11]. The main changes in the structure of Ln coordination polyhedron and in the charge distribution in the nearest surroundings of Ln 3 + ion in dimeric carboxylates with Phen or 2,2 0 -bipyridine (Bpy) of the kind are conditioned by high ''sensitivity'' of bonding of the bridging-cyclic carboxylic group to the type and size of carboxylate ligand [9,12]. Introduction of the methylene group in the carboxylate ligand leads to weakening the steric hindrances and to decrease in the distortions of the lanthanide coordination polyhedron thanks to moving the voluminous fragment from the Ln 3 + ion and to bending of the ligand.…”

“…Contributions of radiative and nonradiative processes to the lifetimes measured are analyzed. The ligand lowest triplet state in lanthanide naphthylcarboxylate complexes belongs to carboxylate anion in contrast to many lanthanide phenylcarboxylates and aliphatic carboxylates with Phen, in which the lowest triplet state is related to Phen ligand [9,10]. Relation between the type of naphthylcarboxylate anion and the carboxylate triplet state energy is investigated.…”

Synthesis, crystal structure, supramolecular assembly, and thermal stability of two new lanthanide coordination polymers based on α-naphthoxyacetate

“…Up to now, the studies on lanthanide frameworks with naphthoxyacetate have been scarcely investigated [17][18][19]. In addition, naphthoxyacetate derivatives as a kind of plant auxins can promote the metabolism and photosynthesis of plant and stimulate the germination of the crops, etc.…”