How minor structural changes generate major consequences in photophysical properties of RE coordination compounds; resonance effect, LMCT state

Lanthanide coordination compounds of the formula Na[Ln(L)4] (1Ln), where Ln ¼ La3þ, Eu3þ, Gd3þ, Tb3þ, L ¼ [L] and HL ¼ dimethyl(4-methylphenylsulfonyl)amidophosphate, were synthesized. Their structural and spectroscopic properties were discussed in detail based on X-ray diffraction measurements, IR spectroscopy, absorption and emission spectroscopy at 293 and 77 K and theoretical calculations of the intramolecular energy transfer (IET) rates. DFT calculations were used to investigate the 1Ln electronic properties required to calculate the transition rates. 30 and 22 pathways of intramolecular nonradiative energy transfer were examined in the case of 1Eu and 1Tb, respectively. It is shown that the main pathway for sensitization of the lanthanide emission is either the triplet (1Eu) or singlet (1Tb) transfer, occurring mainly through the exchange mechanism. The energy rates for energy transfer from S1 and T1 equal WS ¼ 1:53 105 s 1 (1Eu), WT ¼ 5:14 106 s 1 (1Eu) and WS ¼ 4:09 107 s 1 (1Tb), WT ¼ 6:88 105 s 1 (1Tb). The crucial role of the 7F5 level in the energy transfer process of 1Tb and the participation of the LMCTstate in the depopulation of the ligand singlet state of 1Eu were demonstrated. The influence of the resonance effect on the splitting of the 7F1 level in 1Eu was analyzed. By comparing the properties of 1Ln with the properties of 2Ln coordination compounds, sharing the same ligand and crystallizing in the same crystallographic system (monoclinic), but with a different space group, it is demonstrated how slight structural changes can affect the photophysical properties of Ln compounds.publishe

Crystal structure of {μ-6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethanylylidene)]diphenolato}(methanol)(nitrato)nickel(II)sodium

In the molecular structure of the title compound, [NaNi(C18H18N2O4)(NO3)(CH3OH)], the Ni2+ ion has a slightly distorted square-planar coordination environment defined by two N and two O atoms which belong to a Schiff base ligand, viz. 6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(nitrilomethanylylidene)]diphenolate. Seven O atoms form the coordination environment of the Na+ ion: four from the Schiff base ligand, two from a bidentate chelating nitrate anion and one O atom from a coordinating methanol molecule. In the crystal, the bimetallic complexes are assembled into chains along the b-axis direction via weak C—H...O hydrogen-bond interactions. Neighbouring chains are in turn connected through bifurcated O—H...O hydrogen bonds that involve the coordinating methanol molecules and the nitrate anions, and through π–π stacking interactions between phenyl rings of neighbouring molecules

{Dimethyl [(phenylsulfonyl)amido]phosphato-κ2O,O′}bis(triphenylphosphane-κP)copper(I)

In the title complex, [Cu(C8H11NO5PS)(C18H15P)2], the CuI ion is coordinated by two triphenylphosphane molecules and two O atoms of the chelating dimethyl(phenylsulfonyl)amidophosphate anion, generating a squashed CuO2P2 tetrahedron. In the six-membered chelate ring, the Cu, P and O atoms are almost coplanar (r.m.s. deviation = 0.024 Å), with the N and S atoms displaced in the same direction, by 0.708 (5) and 0.429 (2) Å, respectively