The reaction of Ln(NO3)(2)6H(2)O (Ln = Nd, Sm, Eu, Tb, Dy, Tm and Yb) with the respective enantiopure (R)-(-)-2-phenylbutyric or (S)-(+)-2-phenylbutyric acid (R/S-2-HPhBut) and 4,7-diphenyl-1,10-phenanthroline (Bphen) allows the isolation of chiral dinuclear compounds of the formula [Ln(2)(mu-R/S-2-PhBut)(4)(R/S-2PhBut)(2)(Bphen)(2)] where Ln = Nd3+ (R/S-Nd-a), Sm3+ (R/S-Sm-a), Eu3+ (R/S-Eu-a), Tb3+ (R/S-Tb-a and R/S-Tb-b), Dy3+ (R/S-Dy-a and R/S-Dy-b), Tm3+ (R/S-Tm-b) and Yb3+ (R/S-Yb-b). Single crystal X-ray diffraction was performed for compounds S-Eu-a and S-Tm-b. Powder crystal X-ray diffraction was performed for all complexes. From the crystallographic data two different structural motifs were found which are referred to as structure type a and structure type b. In structure type a, the Ln(3+) atoms are bridged through four R or S-2-PhBut ligands with two different kinds of coordination modes whereas in structure type b the two Ln(3+) atoms are bridged through four R or S-2-PhBut ligands showing only one kind of coordination mode. For those lanthanide ions exhibiting both structure types, Tb3+ and Dy3+, a difference in the luminescence and magnetism behavior is observed. All compounds (except R/S-Tm-b) exhibit sensitized luminescence, notably the Eu3+ and Tb3+ analogues. Circular Dichroism (CD) and Circular Polarized Luminescence (CPL) in the solid state and in 1 mM dichloromethane (DCM) solutions are reported, leading to improved chiroptical properties for the DCM solutions. The asymmetry factor (g(lum)) in 1 mM DCM is +/- 0.02 (+ for R-Eu-a) for the magnetically allowed transition D-5(0) -> F-7(1) and +/- 0.03 (+ for R-Tb-a and R-Tb-b) for the D-5(4) -> F-7(5) transition. Magnetic properties of all compounds were studied and the Dy3+ compound with the structural motif b (R-Dy-b) shows Single Molecular Magnet (SMM) behavior under a 0 T magnetic field. However, R-Dy-a is a field-induced SMM
Dinuclear enantiopure Ln3+ complexes with (S-) and (R-) 2-phenylbutyrate ligands. Luminescence, CPL and magnetic properties
Zinna, Francesco;Di Bari, Lorenzo;
2024-01-01
Abstract
The reaction of Ln(NO3)(2)6H(2)O (Ln = Nd, Sm, Eu, Tb, Dy, Tm and Yb) with the respective enantiopure (R)-(-)-2-phenylbutyric or (S)-(+)-2-phenylbutyric acid (R/S-2-HPhBut) and 4,7-diphenyl-1,10-phenanthroline (Bphen) allows the isolation of chiral dinuclear compounds of the formula [Ln(2)(mu-R/S-2-PhBut)(4)(R/S-2PhBut)(2)(Bphen)(2)] where Ln = Nd3+ (R/S-Nd-a), Sm3+ (R/S-Sm-a), Eu3+ (R/S-Eu-a), Tb3+ (R/S-Tb-a and R/S-Tb-b), Dy3+ (R/S-Dy-a and R/S-Dy-b), Tm3+ (R/S-Tm-b) and Yb3+ (R/S-Yb-b). Single crystal X-ray diffraction was performed for compounds S-Eu-a and S-Tm-b. Powder crystal X-ray diffraction was performed for all complexes. From the crystallographic data two different structural motifs were found which are referred to as structure type a and structure type b. In structure type a, the Ln(3+) atoms are bridged through four R or S-2-PhBut ligands with two different kinds of coordination modes whereas in structure type b the two Ln(3+) atoms are bridged through four R or S-2-PhBut ligands showing only one kind of coordination mode. For those lanthanide ions exhibiting both structure types, Tb3+ and Dy3+, a difference in the luminescence and magnetism behavior is observed. All compounds (except R/S-Tm-b) exhibit sensitized luminescence, notably the Eu3+ and Tb3+ analogues. Circular Dichroism (CD) and Circular Polarized Luminescence (CPL) in the solid state and in 1 mM dichloromethane (DCM) solutions are reported, leading to improved chiroptical properties for the DCM solutions. The asymmetry factor (g(lum)) in 1 mM DCM is +/- 0.02 (+ for R-Eu-a) for the magnetically allowed transition D-5(0) -> F-7(1) and +/- 0.03 (+ for R-Tb-a and R-Tb-b) for the D-5(4) -> F-7(5) transition. Magnetic properties of all compounds were studied and the Dy3+ compound with the structural motif b (R-Dy-b) shows Single Molecular Magnet (SMM) behavior under a 0 T magnetic field. However, R-Dy-a is a field-induced SMMI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
