Triphenylphosphane Oxide Complexes of Lanthanide Nitrates: Polymorphs and Photophysics

Abstract

A series of mer‐[Ln(NO3)3(Ph3PO)3] complexes were prepared from Ln(NO3)3·xH2O and Ph3PO in chloroform (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, and Er). The La and Nd complexes were 0.25 CHCl3 solvates, whereas the others were solvent‐free. The identical reaction using Yb(NO3)3·xH2O produced the unique salt trans‐[Yb(NO3)2(Ph3PO)4][Yb(NO3)4(Ph3PO)]·Et2O. All nitrate ions in all complexes are η2‐chelating. A comparison of the various [Ln(NO3)3(Ph3PO)3] structures, including those in the literature, reveals at least four common polymorphs, each of which is represented by isomorphic structures of multiple Ln ions. Luminescence of mer‐[Ln(NO3)3(Ph3PO)3] (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, and Dy), trans‐[Yb(NO3)2(Ph3PO)4][Yb(NO3)4(Ph3PO)] and Ph3PO assignments are reported. Latva's empirical rule allows for the antenna effect, in which energy is transferred from the triplet state of the Ph3PO ligand, to occur only for Tb3+. Excitation via Ph3PO results in strong green luminescence for Tb3+ having twice the intensity as that which results from direct excitation of the f‐f transitions.

Drastic Enhancement of Photosensitized Energy Transfer Efficiency of a Eu(III) Complex Driven by Arsenic

“…The intensity of the emission in the PL spectra was normalized at 593 nm, which was derived from the magnetic dipole transition ( 5 D 0 → 7 F 1 ). Considering a previous report on the optical properties of [Eu­(Ph 3 PO) 3 (NO 3 ) 3 ], we assigned an excitation band between 250 and 300 nm to the excitation of antenna ligands, where strong peaks were observed in the diffuse reflection spectra (Figure b) . The PL spectra suggested that the intensity ratio ( I ED / I MD ) of the emission maxima of the electric dipole transition (618 nm) and magnetic dipole transition (593 nm) for 1-a was larger than that for 2-a .…”

Triphenylarsane Oxide Complexes of Lanthanide Nitrates: Polymorphs and Photophysics

“…White crystalline products were precipitated from these solutions upon addition of ethyl ether. In contrast to Ph 3 PO complexes, which in almost all cases form mer ‐[ Ln (NO 3 ) 3 (Ph 3 PO) 3 ], the Ph 3 AsO products precipitated from CHCl 3 seemed to favor trans ‐[ Ln (NO 3 ) 2 (Ph 3 AsO) 4 ]NO 3 ( 1 ) ( Ln = Y, Eu, Tb, Dy) over mer ‐[ Ln (NO 3 ) 3 (Ph 3 AsO) 3 ] ( 2 ) ( Ln = Sm) species, as determined via elemental analysis (Table ).…”

“…Amongst the three meridional nitrate ligands, an “outer” nitrate lies in the meridional plane of the molecule, while the center and remaining outer nitrate planes are coplanar with the axial Ph 3 AsO– Ln –OAsPh 3 vector. Both arrangements 1 and 2 have been observed in the better‐studied Ph 3 PO‐ Ln complexes, but 2 is by far the more commonly observed, with 1 having been noted only for Ln = Dy and Lu,, and in the unusual trans ‐[Yb(NO 3 ) 2 (Ph 3 PO) 4 ][Yb(NO 3 ) 4 (Ph 3 PO)] · Et 2 O …”

“…We have recently reported a significant antenna effect of triphenylphosphane oxide upon Tb III emission in mer ‐[Tb(NO 3 ) 3 (Ph 3 PO) 3 ] . This behavior was rationalized as the result of an n→π* excitation band associated with ligand phenyl groups that induced lanthanide emission via either direct metal ion excitation or a ligand‐to‐metal charge transfer (LMCT).…”

Effect of single variable factor of electron‐acceptor on the luminescence quantum yield of terbium complex

“…Both compounds emit green (CIE: 0.3149, 0.5789, Figure 3c) and greenish-yellow luminescence (CIE: 0.4089, 0.5344, Figure 3c), with narrow emission bands in 450-650 nm. [25,32] The maximum intensities at 489, 543, 586, and 620 nm are assigned to the 5 D 4 ! 7 F J (J = 3-6) transitions of Tb 3 + (Figure 3a, 3b).…”