A new synthetic route towards binuclear 3d-4f complexes, using non-compartmental ligands derived from o-vanillin. Syntheses, crystal structures, magnetic and luminescent properties

Article abstract of DOI:10.1039/c3nj00199g

Sixteen new 3d-4f binuclear complexes have been obtained using two Schiff-base ligands, Hvalampy and Hvalaepy, derived from the reaction of o-vanillin and 2-aminomethyl-pyridine or 2-(2-aminoethyl)-pyridine, respectively. Hvalaepy ligand: [Zn(valaepy)

Full text of DOI:10.1039/c3nj00199g

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A new synthetic route towards binuclear 3d-4f complexes, using non-
compartmental ligands derived from o-vanillin. Syntheses, crystal structures,
magnetic and luminescent properties†
Masood Sarwar,a Augustin M. Madalan,*a Carmen Tiseanu,*b Ghenadie Novitchi,c Catalin
Maxim,a Gabriela Marinescu,d Dominique Luneau,e Marius Andruh*a
a
University of Bucharest, Faculty of Chemistry, Inorganic Chemistry Laboratory, Str. Dumbrava Rosie nr. 23,
020464ꢀBucharest, Romania; Eꢀmails: madalin.madalan@g.unibuc.ro; marius.andruh@dnt.ro
b
National Institute for Laser, Plasma and Radiation Physics, Laboratory of SolidꢀState Quantum Electronics, PO
Box MGꢀ36, Magurele, 077125, Romania; Eꢀmail: tiseanuc@yahoo.com
c
Laboratoire National des Champs Magnétiques Intenses, CNRS UPRꢀ3228, 25 rue des Martyrs, 38042 Grenoble
Cedex 9, France
d“Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy, Coordination and Supramolecular
Chemistry Laboratory, Spl. Independentei no. 202, 060021ꢀBucharest, Romania
e
Laboratoire des Multimatériaux et Interfaces, Groupe de Crystallographie et Ingénierie Moléculaire, Université
Claude Bernard Lyon 1, UMR CNRS 5615, Bâtiment BertholletꢀDomaine Scientifique de la Doua, 69622
Villeurbanne Cedex, France
† Dedicated to Professor Miguel Julve, a great scientist and friend, on the occasion of his 60th
birthday.
Sixteen new 3dꢀ4f binuclear complexes have been obtained using two Schiffꢀbase ligands
derived from oꢀvanillin and 2ꢀaminomethylꢀpyridine and, respectively, 2ꢀ(2ꢀaminoethyl)ꢀ
pyridine: Hvalampy and Hvalaepy. Hvalaepy ligand: [Zn(valaepy)2Sm(O2NO)3]·CH3CN 1;
[Ni(valaepy)2Eu(O2NO)3(H2O)]·CH3CN
[Ni(valaepy)2Dy(O2NO)3(H2O)]·CH3CN
2;
4;
[Ni(valaepy)2Gd(O2NO)3(H2O)]·CH3CN
[Ni(valaepy)2Ho(O2NO)3(H2O)]·CH3CN
3;
5;
[Cu(valaepy)2Eu(O2NO)3]·CH3CN 6; [Cu(valaepy)2Gd(O2NO)3]·CH3CN 7; Hvalampy ligand:
[Zn(valampy)2Pr(O2NO)3]·CH3CN
[Zn(valampy)2Gd(O2NO)3]·CH3CN
[Zn(valampy)2Dy(O2NO)3]·CH3CN
8,
[Zn(valampy)2Sm(O2NO)3]·CH3CN
[Zn(valampy)2Tb(O2NO)3]·CH3CN
[Zn(valampy)2Eu(O2NO)3]·CH3CN
9;
11;
13;
10;
12;
[Ni(valampy)2La(O2NO)3(H2O)2]·2H2O 14, [Ni(valampy)2Sm(O2NO)3(H2O)2]·2H2O 15;
[Ni(valampy)2Eu(O2NO)3(H2O)]·2CH3CN 16. The crystal structures of the 16 compounds can be
described as resulting from the coordination of two valaepyꢀ (or valampyꢀ) ligands to the 3d
metal ions through two phenoxo oxygen atoms and nitrogen atoms, arising from the pyridyl and
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azomethynic groups. In all these compounds the 3d and 4f metal ions are bridged by the phenoxo
oxygen atoms. The comparative analysis of the crystal structures shows several differences,
which arise mainly from the stereochemical preference of the 3d metal ions. These ions arrange
the two organic ligands in positions that favour or not the coordination of the methoxy groups to
the lanthanide ions. The magnetic properties of compounds 2, 3, 4, 5, 7, 14, 15, and 16 have been
investigated. The exchange interactions between NiII and GdIII in 3, and between CuII and GdIII in
7 were found to be ferromagnetic (JNiGd = 1.56 cmꢀ1; JCuGd = 4.94 cmꢀ1; H = ꢀJSGdSM). For the
3dꢀ4f binuclear complexes derived from Hvalampy ligand (namely 8-13) the photoluminescence,
(PL), properties were investigated in the Vis spectral region. The results evidence for relatively
stronger antenna effect in 9 and 11 compared to 8, 12 and 13.
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Introduction
Since the pioneering work of Gatteschi and his coꢀworkers on the magnetic properties of
CuIIꢀGdIII complexes,1 the molecular chemistry of 3dꢀ4f heterometal systems is of current
interest. First of all, strictly binuclear 3dꢀ4f compounds are useful models for studying the factors
influencing the nature (ferroꢀ/antiferromagnetic) and the strength of the 3dꢀ4f exchange
interaction.2 More recently, it has been shown that the combination of 3d and 4f metal ions
within the same molecular entity represents a successful strategy to obtain Single Molecule
Magnets,3 and magnetic refrigerants.4 Moreover, when the 3d metal ion is Zn2+, this ion and the
organic ligand form an antenna that efficiently sensitizes the luminescence of the rare earth
cations.5
The first binuclear complexes of interest in molecular magnetism have been synthesized
by Costes et al.,6 and by Kahn et al.7 Costes’s strategy is based on the use of dissymmetric
compartmental Schiffꢀbase ligands derived from oꢀvanillin and various diamines with primary
amino groups. These are ligands with a N2O2 coordination site, hosting the 3d ion, and an open
O2O2 coordination site, able to accommodate the larger 4f metal ions. The synthesis of such
complexes is a stepwise process, in which the 3d ion is first introduced, the resulting complex
being further used as a ligand towards the 4f ion. Although these ligands are particularly suited
for the design of 3dꢀ4f complexes, it has been shown that heterometallic 3dꢀ3d’ complexes can
be obtained as well.8 Actually, the potential of oꢀvanillin to generate ligands is broader, being not
limited to compartmental ligands. For example, the condensation reactions between oꢀvanilin
and organic molecules containing only one primary amino group and another coordinating group
lead to ligands with quite interesting coordination abilities.9 The relative position of the donor
atoms (more precisely, the presence and the position of the methoxyꢀgroup from the oꢀvanillin)
confers to these ligands a polynucleating function, although the nuclearity of the resulting
systems is not easily predictable. Such a ligand was obtained by reacting oꢀvanillin with 2ꢀ
aminometylꢀpyridine.10 Its reaction with Cu2+ ions leads to a tetranuclear complex with a
heterocubane topology.
We now report here on three families of 3dꢀ4f binuclear complexes obtained using two
very similar ligands, which result from the condensation reactions between oꢀvanillin and 2ꢀ
aminomethylꢀpyridine and, respectively, 2ꢀ(2ꢀaminoethyl)ꢀpyridine (Hvalampy; Hvalaepy –
Scheme 1). In order to check their ability to generate heterometal complexes, we have associated
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the Ln3+ ions with three different 3d metal ions: Ni2+, Cu2+, and Zn2+. For some of these
compounds the magnetic and photophysical properties have been investigated.
Experimental
Synthesis. All the sixteen binuclear MIILnIII complexes, (MII = Ni, Cu, Zn) have been
synthesized in a stepꢀwise manner without the isolation of mononuclear complex. The synthetic
procedure consists in the inꢀsitu formation of Schiffꢀbase ligand HL1 (Hvalampy) or HL2
(Hvalaepy) by the condensation reaction of oꢀvanillin (2 mmol) and 2ꢀaminomethylꢀpyridine (2
mmol) or 2ꢀ(2ꢀaminoethyl)ꢀpyridine (2 mmol), respectively, in acetonitrile solvent under
continuous stirring for 30 minutes, followed by the addition of triethylamine base, (Et3N) (4.8
mmol). This is followed by the addition of acetonitrile solution (10 ml) of M(NO3)2·nH2O (M =
Ni, Zn, n = 6; M = Cu, n = 3) (1 mmol) and continuous stirring of reaction mixture for one hour.
Then acetonitrile solution (10 ml) of corresponding hydrated lanthanide nitrate, Ln(NO3)3·6H2O
(LnIII = La, Pr, Sm, Gd) or Ln(NO3)3·5H2O (LnIII = Eu, Tb, Dy, Ho) (1 mmol) is added and the
reaction mixture is continuously stirred for one more hour. The resulting solution is then filtered
and left for slow evaporation. After one week suitable quality green (in the case of NiIILnIII),
dark green (CuIILnIII) and yellow or orange (ZnIILnIII) single crystals are obtained. These crystals
are collected by filtration and washed several times by the 1:1 mixture of acetonitrile and diethyl
ether and dried in air.
Physical measurements. The IR spectra (KBr pellets) were collected on a Bruker Tensor 37
spectrophotometer in the 4000 ꢀ 400 cm−1 range. Magnetic measurements were performed on
polycrystalline samples with a Quantum Design MPMSꢀXL SQUID magnetometer equipped
with a 5 T magnet. All data were corrected for the contribution of the sample holder and the
diamagnetism of the samples estimated from Pascal’s constants.
The photoluminescence measurements were carried out using a Fluoromax 4 spectrofluorometer
(Horiba) operated in both the fluorescence and the phosphorescence mode. The repetition rate of
the xenon flash lamp was 25 Hz, the integration window varied between 0.3 and 3 s, the delay
after flash varied between 0.03 and 10 ms, and up to 100 flashes were accumulated per data
point. The slits were varied from 0.001 nm to 10 nm in excitation as well as emission. PL decays
were measured by using the “decay by delay” feature of the phosphorescence mode. For the lowꢀ
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temperature measurements, the liquid nitrogen Dewar built for Fluoromax was used. The laser
excited time resolved emission spectra were recorded at room temperature using a nitrogen laser
with excitation wavelength at 337 nm and wavelength tunable NT340 Series EKSPLA OPO
(Optical Parametric Oscillator) operated at 20 Hz as excitation light source and an intensified
CCD camera (Andor Technology) coupled to a spectrograph (Shamrock 303i, Andor) as
detection system. The time ꢀresolved PL spectra were collected using the box car technique. The
emission was detected in the spectral range of 400 nm < λem < 750 nm with a spectral resolution
of 0.3 nm. The PL decays were analyzed by fitting with a multiexponential function f(t) using the
commercial software (OriginPro 8): f(t) =∑ Ai exp(− t/τi )+ B where Ai is the decay amplitude, B
is a constant (the baseline offset) and τi is the time constant of the decay i.
Crystallography. Xꢀray diffraction measurements were performed on a STOE IPDS II
diffractometer, operating with MoꢀKa (λ = 0.71073 Å) Xꢀray tube with graphite monochromator.
The structures were solved by direct methods and refined by fullꢀmatrix least squares techniques
based on F2. The nonꢀH atoms were refined with anisotropic displacement parameters.
Calculations were performed using SHELXꢀ97 crystallographic software package. A summary
of the crystallographic data and the structure refinement for crystals 1-7, 9-11, 13, 15, and 16 are
given in Table 1 (for the compounds 8, 12 and, 14 were determined only the unit cell parameters
– See ESI). CCDC reference numbers: 920453 – 920465.
Results and discussion
We found that both ligands are able to generate binuclear 3dꢀ4f complexes. The synthetic
approach consists of three successive reactions carried out in situ: (i) the formation of the Schiffꢀ
base by reacting oꢀvanillin with and 2ꢀ(2ꢀaminoethyl)ꢀpyridine and, respectively, 2ꢀ
aminomethylꢀpyridine; (ii) the reaction with the 3d metal salt in the presence of Et3N, which
deprotonates de Schiffꢀbases; (iii) the reaction with the lanthanides nitrates. All the resulted
complexes are characterized by the molar ratio between the ligand and the metal ions 2:1:1.
The following series of complexes have been obtained and crystallographically characterized:
Hvalaepy ligand:
[Zn(valaepy)2Sm(O2NO)3]·CH3CN
1;
[Ni(valaepy)2Eu(O2NO)3(H2O)]·CH3CN
3; [Ni(valaepy)2Dy(O2NO)3(H2O)]·CH3CN
2;
4;
[Ni(valaepy)2Gd(O2NO)3(H2O)]·CH3CN
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[Ni(valaepy)2Ho(O2NO)3(H2O)]·CH3CN
5;
[Cu(valaepy)2Eu(O2NO)3]·CH3CN
6;
[Cu(valaepy)2Gd(O2NO)3]·CH3CN 7;
Hvalampy ligand:
[Zn(valampy)2Pr(O2NO)3]·CH3CN
[Zn(valampy)2Gd(O2NO)3]·CH3CN
[Zn(valampy)2Dy(O2NO)3]·CH3CN
8,
[Zn(valampy)2Sm(O2NO)3]·CH3CN
[Zn(valampy)2Tb(O2NO)3]·CH3CN
[Zn(valampy)2Eu(O2NO)3]·CH3CN
9;
11;
13;
10;
12;
[Ni(valampy)2La(O2NO)3(H2O)2]·2H2O 14, [Ni(valampy)2Sm(O2NO)3(H2O)2]·2H2O 15;
[Ni(valampy)2Eu(O2NO)3(H2O)]·2CH3CN 16.
The aggregation of the binuclear complexes can be described as resulting from the coordination
of two valaepyꢀ (or valampyꢀ) ligands to the 3d metal ions through two phenoxo oxygen atoms
and nitrogen atoms, arising from the pyridyl and azomethynic groups. In all these compounds the
3d and 4f metal ions are bridged by the phenoxo oxygen atoms.
Description of the structures
Let us start with the three families of complexes generated by the Hvalaepy Schiffꢀbase. All of
them are binuclear, with some subtle differences imposed by the stereochemical preferences of
the 3d metal ions. The crystallographic investigation of 1 (Figure 1) reveals that the coordination
modes of the two ligand molecules towards zinc are different: one of them (valaepyꢀA) is
coordinated to the zinc ion through the phenoxo oxygen atom and the two nitrogen atoms, while
the second one (valaepyꢀB) is coordinated through the phenoxo oxygen and the azomethynic
nitrogen, the pyridyl arm being uncoordinated. Consequently, the zinc ion is pentacoordinated,
with a trigonal bipyramidal geometry. The trigonal plane is made by one oxygen (Zn1 – O2 =
2.033(3) Å) and by two nitrogen atom arising from the pyridyl group of the valaepyꢀA ligand
(Zn1 – N2 = 2.102(4) Å) and by the azomethynic nitrogen arising from the valaepyꢀB ligand (Zn
– N3 = 2.071(4) Å). The apical positions are occupied by a phenoxo oxygen (Zn1 – O4 =
2.047(3) Å), and by a nitrogen atom from the tridentate valaepy ligand Zn1 – N1= 2.037(4) Å.
The samarium ion is located into the open cavity described by the four oxygen atoms arising
from the two ligand molecules. The methoxy group from valaepyꢀA is coordinated to the
samarium ion (Sm1 – O1 = 2.544(3) Å), while the other one, arising from the valaepyꢀB
molecule, can be considered as semicoordinated (Sm1 – O3 = 2.900(4) Å). Taking into account
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only the samarium – oxygen distances in the range 2.312(3) – 2.565(5) Å, the samarium ion is
nineꢀcoordinated: two bridging phenoxo oxygens, six oxygen atoms from the bidentate nitrato
ligands, and one oxygen from the methoxy group. The intramolecular distance between the metal
centers is: ZnꢁꢁꢁSm = 3.5871(6) Å.
The four Ni(valaepy)2Ln complexes (2, 3, 4, and 5) are isomorphous crystallizing in the
monoclinic P21/n space group. Since their structures are similar, we will discuss here only the
crystal structure of 2 (Figure 2). First of all, we notice that the nickel(II) ion is hexacoordinated,
with an octahedral geometry. This stereochemistry is very characteristic for the hexacoordinated
nickel ions. The coordination sphere is formed by two azomethynic and two pyridyl nitrogen
atom, and by two phenoxo oxygens, with bond distances varying between 2.080(2) and 2.114(2)
Å. The europium and nickel ions are bridged by two phenoxo oxygens. The coordination number
of europium is 9 (two phenoxo oxygen atoms, six oxygens from three chelating nitrato ligands,
and one aqua ligand). The bond distances vary between 2.3082(16) and 2.562(2) Å, the shortest
bonds involving the phenoxo oxygen atoms (Eu1 – O2 = 2.3082(16); Eu1 – O4 = 2.3679(16) Å).
Interestingly, the two methoxy groups are no more coordinated to the europium ion. This is
somehow surprising, since the methoxy groups from the ligands derived from oꢀvanillin play an
active role in holding the rare earth cations within heterometallic complexes. In this case, the
stereochemical requirements of nickel(II), that is, its strong preference for the octahedral
geometry orient the two valaepy molecules such as the two methoxy groups are too far from the
europium ion to be coordinated. The intramolecular NiꢁꢁꢁEu distance is 3.4898(3) Å.
We
have
structurally
characterized
two
Cu(valaepy)2Ln
complexes:
[Cu(valaepy)2Eu(O2NO)3]·CH3CN 6, and [Cu(valaepy)2Gd(O2NO)3]·CH3CN 7, which are
isomorphous. They are isomorphous with 1 as well. We will describe here the structure of 6
(Figure 3). The two valaepy ligands act differently: one molecule (valaepyꢀC) acts as a tridentate
ligand towards copper, while the other one, valaepyꢀD, as a bidentate ligand towards copper. The
copper is pentacoordinated by two phenoxo oxygens (Cu1 – O2 = 1.991(2), Cu1 – O4 = 1.931(3)
Å), one pyridyl nitrogen (Cu1 – N2 = 2.175(3) Å) and one azomethynic nitrogen arising from the
valepyꢀC ligand (Cu1 – N1 = 1.946(3) Å), and by one azomethynic nitrogen from valaepyꢀD
(Cu1 –N3 = 2.084(3) Å). The pyridyl arm from the valaepyꢀD molecule is uncoordinated. The
copper and europium ions are again bridged by the two phenoxo oxygen atoms (Eu1 – O2 =
2.388(2); Eu1 – O4 = 2.336(3) Å). The coordination number of europium in 6 is 9. The other
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seven oxygen atoms arise from one methoxy group from valaepyꢀC molecule (Eu1 – O1 =
2.555(3) Å) and from three bidentate nitrato ligands (bond distances ranging between 2.467(4)
and 2.547(4) Å). The methoxy group from the valaepyꢀD ligand is semicoordinated (Eu1 – O3 =
2.792(3) Å).
Selected bond distances and angles for compounds 1 – 7 are collected in Table 2.
Using the Schiffꢀbase ligand derived from oꢀvanillin and 2ꢀaminomethylꢀpyridine
(Hvalampy) we obtained six ZnIILnIII complexes (8 – 13) and three NiIILnIII complexes (14 – 16).
Complexes 8 – 13 are isomorphous. The main difference between their structures and that
discussed for [Zn(valaepy)2Sm(O2NO)3]·CH3CN 1 and the isostructural [Cu(valaepy)2Ln] family
(compounds 5 and 6) arises from the stereochemistry of the zinc ions, which are now
hexacoordinated (Figure 4). The zinc ion in 9 shows a strongly distorted geometry, with two long
bonds (involving the pyridyl nitrogen atoms, Zn1 – N2 = 2.3956(16) Å), and two four shorts
bonds (involving the azomethynic nitrogen and the phenoxo oxygen atoms: Zn1 – N1 =
2.0603(14); Zn1 – O2 = 2.0504(10) Å). Since the coordination sphere for a d10 ion is more
flexible than that of NiII (see structure of 2 above), the two methoxy groups from the two valaepy
ligands come closer to the lanthanide cations (for example, in 9: Sm1 – O1 = 2.7024(13) Å). The
coordination number of samarium in 9 is eight (two phenoxo bridging oxygen atoms and six
oxygen atoms arising from three chelating nitrato ligands, with distances varying between
2.3551(10) and 2.5395(13) Å, the shortest bonds involving the bridging oxygen atoms). The two
methoxy groups can be considered as being semicoordinated. The intramolecular distance
between the zinc and samarium ions in 9 is 3.594 Å. The acetonitrile molecules are disordered on
two positions with the N atom lying on an inversion centre.
Complexes 14 – 15 are also isomorphous and crystallize in the monoclinic C2/n space
group. We have obtained a good quality structure for the samarium derivative, 15, and its
structure will be described in detail. The unit cell parameters for 14 and 15 are very similar (for
the lanthanum derivative 14 were determined only the unit cell parameters). The stereochemistry
of the nickel ions is octahedral and the orientation of the two valampy ligands is imposed by the
stereochemical preference of the nickel ions (Figure 5a). Consequently, like in complexes 2 – 5,
the methoxy group cannot coordinate to the lanthanide cations. The distances between samarium
and the two methoxy oxygen atoms are 4.087(3) and 4.139(3) Å. The nickel and lanthanide ions
are held together only by the two phenoxo bridges. The samarium ion in 15 has a coordination
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number of 10: two phenoxo oxygens, six others from three chelating nitrato ligands and two aqua
ligands. The aqua ligands are involved in intramolecular hydrogen bond interactions with the
methoxy oxygen atoms, O14wꢁꢁꢁO1 = 2.780(4) Å and O15wꢁꢁꢁO4 = 2.793(4) Å. The
intramolecular NiꢁꢁꢁSm is 3.5293(5) Å.
The NiIIEuIII complex with the valampy ligand (compound 16) crystallizes in a different
space group (triclinic, Pꢀ1). The stereochemistry of the nickel ions is also octahedral, but the
lanthanide ion has a coordination number of 9: two phenoxo oxygens, six oxygen atoms from
three chelating nitrato ligands and only one aqua ligand (Figure 5b). The Eu – O bond lengths
range between 2.335(8) and 2.564(7) Å. The aqua ligand is involved in intramolecular hydrogen
bond interactions with one of the uncoordinated methoxy groups, O14wꢁꢁꢁO3 = 2.778(14) Å.
Selected bond distances and angles for compounds 9 – 11, 13, 15 and 16 are collected in
Table 2.
The comparative analysis of the five crystal structures described above showed several
differences, which arise mainly from the stereochemical preference of the 3d metal ions. These
ions arrange the two organic ligands in positions that favour or not the coordination of the
methoxy groups to the lanthanide ions.
Magnetic properties
The magnetic properties of complexes 2, 3, 4, 5, 7, 14, 15, and 16 have been investigated.
The simplest cases are those of complexes 14,
[Ni(valampy)2La(O2NO)3(H2O)2]·2H2O, contains only one paramagnetic ion, and compounds 3
and 7 contain the isotropic gadolinium(III) ion. The MT vs. T curve for compound 14 is
represented in Figure S1. The value of the
MT product at room temperature is 1.25 cm3molꢀ1K
and agrees with the presence of a single paramagnetic centre (NiII) in the complex. The
MT
3
and 7: compound 14,
χ
χ
χ
product remains constant down to 30 K and then it decreases abruptly reaching 1.00 cm3molꢀ1K
at 2 K. The deviation from the Curie low is due to the zero field splitting associated to NiII ions.
The best fit to the data, using the Hamiltonian HZFS = D[Sz2 – 1/3S(S + 1)], leads to the following
values: g = 2.24, D = 2.64 cmꢀ1.
For compounds 3 and 7 the
χMT vs. T curves are presented in Figure 6. In both cases the
room temperature values of the
χ
MT product (3: 9.67 cm3molꢀ1K; 7: 8.43 cm3molꢀ1K) correspond
to the expected ones for uncoupled NiIIGdIII and, respectively, CuIIGdIII pairs of ions. By
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lowering the temperature, both compounds show a ferromagnetic coupling between the two
metal ions, as indicated by the increase of the MT product, which reaches the maximum values
χ
of 13.46 cm3molꢀ1K (for 3) and 10.21 cm3molꢀ1K (for 7). Both values are in line with ground
states having S = 9/2 and S = 4, respectively. The spin of the ground state is also confirmed by
magnetization vs. field measurements (see insets to Figures 6a and 6b). In order to fit the data,
the isotropic HDVV spin Hamiltonian has been employed: H = ꢀJSGdSM. The following values
have been obtained by fitting the experimental data: JNiGd = 1.56 cmꢀ1; gav = 2.08 (3); JCuGd = 4.94
cmꢀ1; gav = 2.00 (7). For compound 3, the quality of the fit does not improve by taking into
account the ZFS effect associated to NiII. One of the important factors influencing the nature and
the magnitude of the CuIIꢀGdIII exchange interaction in bisꢀphenoxoꢀbridged binuclear
conmplexes is the value of the diehedral angle between the O2CuO4 and O2GdO4 planes.6b Low
values of this angle favour stronger ferromagnetic interactions. For compound 7 the value of this
dihedral angle is 2.52º. The value of the J parameter found for compound 7 is lower than
expected, according to the magnetoꢀstructural correlations made by Costes et al.6b In general, the
NiIIꢀGdIII exchange interaction is weaker than the CuIIꢀGdIII one, the corresponding J parameter
ranging between 0.2 and 5 cmꢀ1.3k
For complexes 2, 4, 5, 15 and 16 (Figure 7) the magnetic properties are more complicated
because of the intervening firstꢀorder angular momentum and crystal field effect for the LnIII
ions. For these compounds the variation of the magnetic behaviour arises from the superposition
of two phenomena. One is the result of the exchange interaction between the NiII and LnIII ions.
The second is intrinsic to the LnIII ion and originates from the thermal population of the Stark
levels. In the case of the complexes containing LnIII ions with a good energetic separation
between the ground state and the first excited state only this ground state is thermally populated
at room temperature and the magnetic susceptibility was calculated using the equation:χM
(Ngj2β2/3kT)·J(J + 1), where: gJ = 3/2 + [S(S + 1) ꢀ L(L + 1)]/2J(J + 1); the value of the
MT
product for the heterobimetallic complexes is then:
MT = (Ngj2β2/3k)·J(J + 1) + (Ng2β2/3k)·S(S +
1), where S =1/2 for CuII, S = 1 for NiII). This is the case of complexes 4 and 5: the roomꢀ
temperature values of the
MT product are: 15.21 cm3molꢀ1K (4), and 15.18 cm3molꢀ1K (5),
=
χ
χ
χ
which correspond to the expected ones, calculated using the equation (2). The interaction
between NiII and both DyIII and HoIII was found in many cases to be ferromagnetic.3k This
interaction appears clearly ferromagnetic in the case of the holmium derivative, 5 (Figure 7c).
10

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Let us discuss now the magnetic properties of the NiIISmIII and NiIIEuIII derivatives
(compounds 2, 15, and 16). The complexes of SmIII and EuIII are special cases.11 The first excited
states of these two lanthanide ions lay very close to their ground states, so they are thermally
populated even at room temperature. As a consequence, the values reached by
temperature domain are much above those given equation (1). For the europium complexes, 2
and 16 (Figures 7a and S2), the room temperature values of MT are 2.79 and, respectively, 2.52
χMT in the high
χ
cm3molꢀ1K and steadily decrease as the temperature is lowered to tend to the lowꢀtemperature
limits of (χMT)LT = 1.07 cm3molꢀ1K (for 2) and 1.01 cm3molꢀ1K (for 16). It is interesting to
observe that χMT values at 2 K correspond only to the nickel(II) ions, the europium(III) being
diamagnetic at this temperature.
For the samarium(III) ion the first excited state (6H7/2) is populated at room temperature,
so that the
reached only at very low temperatures. This peculiarity is clearly observed for compound 15
(Figure 7d). By lowering the temperature, MT decreases linearly down to ca. 20 K. Below this
temperature, MT decreases abruptly. The
MT value at about 20 K (1.11 cm3molꢀ1K)
corresponds to the uncoupled NiII and SmIII ions. Considering the contribution of a nickel(II) ion,
χ
MT value is much higher than the expected one (0.089 cm3molꢀ1K). This value is
χ
χ
χ
(
χ
MT)Ni ≈ 1.0 cm3molꢀ1K, and the one of a samarium(III) ion (≈ 0.1 cm3molꢀ1K), the expected
MT value for at 20 K is ≈ 1.1 cm3molꢀ1K. This values agrees well with that observed at 20 K for
χ
compound 15. The decrease of
χMT below 20 K is due to the antiferromagnetic interaction
between NiII and SmIII or the the ZFS effect on the nickel(II) ion, or to a combination of these
factors. Absence of frequency dependence of slow magnetic relaxation was prowed by AC
susceptibility measurements at zero and 0.1 T dc fields for all compounds.
Photophysical properties
We have recently investigated one and twoꢀphoton excited Vis and NIR
photoluminescence (PL) properties of several lanthanide complexes with bicompartmental
ligands derived from oꢀvanillin in the solid state in both steady state and timeꢀresolved modes at
room and liquid nitrogen temperature. 5aꢀb, 5i The results evidenced that, among the Vis emitting
LnIII ions, the TbIII and SmIII complexes exhibited the most intense emission due to an efficient
antenna effect.12 Yet, the PL lifetime of TbIII was relatively small (around 100 ꢂs)5aꢀb and its
increase by almost an order of magnitude from 300 to 80 K5b confirmed the presence of backꢀ
11

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transfer of excitation energy from the excited state of the lanthanide to the triplet state of the
ligand. The emission of DyIII was weaker than that of SmIII and incomplete intramolecular
energy transfer from the ligand to the metal center was evidenced from the emission spectrum.5b
The EuIII emission was strongly quenched at roomꢀtemperature and the antenna effect was
absent, most probably due to a combined effect of the lowꢀlying triplet state of the ligand and
ligand to metal charge ꢀ transfer (LMCT) band.5i
Here, we investigate the roomꢀ temperature emission/excitation spectra and PL decays of
SmIII (9), EuIII (13), GdIII (10), TbIII (11), DyIII (12) and PrIII (8) in the
[Zn(valampy)2Ln(O2NO)3]·CH3CN family measured in the solid state. For the TbIII complex, the
PL decay was measured also at liquid nitrogen temperature (80 K). According to the structural
data presented, all complexes are isomorphous with no LnIII bound aqua ligands in the first
coordination shell.
[Zn(valampy)2Sm(O2NO)3]·CH3CN 9. Upon excitation into the absorption maximum of 9
(390 nm), the SmIII complex exhibits bright orangeꢀred luminescence related to SmIII 4G5/2
ꢀ
4
7
4
6
4
6
6H5/2, G5/2 ꢀ H7/2, G5/2 ꢀ H9/2, G5/2 ꢀ H11/2 transitions centred at 560, 597, 644 nm and 690 ꢀ
1
710 nm (Figure 8a). A broad, ligand type emission was absent. The emission of the ligand ππ*
state of the ligand was peaked around 450 nm as inferred from the photophysical properties of
the GdIII complex, 10, illustrated in the Supporting Information (Figure S3). The excitation
spectrum follows closely the absorption spectrum of 10 (with a maximum peak at ~390 nm,
Figure S3).
In the excitation spectrum of the samarium complex, the most intense band corresponds
to the ligandꢀcentred electronic transition at 390 nm, indicating for an efficient ligand to metal
energy transfer. The ligandꢀtoꢀmetal energy transfer occurs via the triplet states 3ππ* of the ligand
directly to the 4G5/2 level of SmIII most probably via an exchange mechanism13 or via population
4
of the higher excited states with subsequent relaxation to the G5/2 emitting level. Several weak
intensity lines correspond to the fꢀf absorption levels of SmIII (over 50 levels are congested in the
4
spectral range of 400 to 500 nm). The line marked with * corresponds to the F3/2 absorption
(from the ground level 6H5/2) also observed with low intensity in the emission spectrum (at ~ 529
nm).
The 4G5/2 ꢀ 7H5/2 of SmIII has a predominant magnetic dipole character (ꢃJ = 0), whereas
4
7
the G5/2 ꢀ H9/2 transition is predominantly electric dipole transition with hypersensitivity
12

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4
6
property (ꢃJ = 2). The G7/2 ꢀ H7/2 transition peaked at 597 nm is of mixed magnetic and
7
6
electric dipole character. The intensity ratio I(4G5/2 ꢀ H9/2)/I(4G5/2 ꢀ H5/2) is 2.1 which can be
used as a measure for the departure of polarizability of its chemical environment.14a It is also
indicative for the loss of centrosymmetry (the ratio tends to 0 for SmIII in centrosymetric sites)14b
which is in line with the distorted polyhedron around SmIII as determined with the Xꢀray data. PL
decay (measured at λex = 390 nm, λem = 597 nm) is single exponential with a lifetime of ~ 45 ꢂs
(Figure 8b) which further confirms the single coordination environment of SmIII in 9.
[Zn(valampy)2Eu(O2NO)3]·CH3CN 13. Upon excitation at 390 nm, the europium
complex exhibits weak characteristic europium emission at ~ 576.5, 589 ꢀ 591, 615, 645 and 681
5
7
5
7
7
5
7
5
7
ꢀ 699 nm, corresponding to D0 ꢀ F0, D0 ꢀ F1 5D0 ꢀ F2, D0 ꢀ F3 and D0 ꢀ F4 transitions,
respectively. The metal related emission appears superimposed on the ligand related emission
centred at 450 nm (Figure not included). The weak sensitization of europium emission by the
ligands was clarified by the excitation spectrum (Figure 9a). The excitation spectrum is
dominated by the europium fꢀf absorption at 464 nm followed by that at 536 nm corresponding
7
5
7
5
to the F0 ꢀ D2 and F1 ꢀ D1 transitions, respectively. Weak contribution from the ligands
absorption was also detected with maximum intensity around 390 nm. The low intensity of
emission precluded use of EuIII as structural probe, yet some details can be provided by use of
5
7
stronger, laser excitation at 464 nm (Figure 9a). The D0 ꢀ F0 emission transition exhibits one
broad and relatively symmetrical band with a FWHM of 25 cmꢀ1 (our spectral resolution is
around 10 cmꢀ1) and the 5D0 ꢀ 7F1 emission transition shows three lines at ~ 586, 590 and 591 nm.
The intensity ratio corresponding to the electric and magnetic dipole transitions, or asymmetry
ratio, R = I(5D0 ꢀ 7F2)/I(5D0 ꢀ 7F1) is 3.6 which denotes a low symmetry coordination polyhedron
of EuIII in good agreement with the Xꢀray data. PL decay measured on the 5D0 ꢀ 7F2 emission (λex
= 464 nm, λem = 615 nm) can be satisfactorily fitted with single exponential and the lifetime is
around 552 ꢂs (Figure 9b). Overall, the emission data point tot weak ligand to metal energy
transfer in complex 13.
[Zn(valampy)2Tb(O2NO)3]·CH3CN 11. Upon excitation at 390 nm, relative strong green
5
7
emission was observed corresponding to the terbium D4 ꢀ FJ transitions at 492, 544, 585 and
623 nm for J = 6, 5, 4, and 3, respectively and no broad, ligand related emission was observed
5
(Figure 10a). The emission is dominated by the D4 ꢀ 7F5 transition at 544 nm which is of mixed
magnetic and electric dipole character, exhibiting also some ligandꢀinduced pseudoꢀ
13

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hypersensitivity.15 The excitation spectrum measured at λem = 544 nm has a maximum around
390 nm. Note the distinct shape of the excitation spectrum which is found to be very similar to
those of recently reported ZnIIITbIII complexes. 5aꢀb, k The fꢀf absorption of TbIII corresponding to
7
5
the F6 – D4 (at ~ 488 nm) is also observed, but its intensity relative to that of the ligand
absorption is negligible. Overall, the results are indicative of strong ligand to metal energy
transfer. The PL decay measured at λem = 544 nm is reasonable fitted with single exponential
function with lifetime value of 500 ꢂs (Figure 10b). The rather short value indicates for strong
5
nonꢀradiative quenching of the metastable D4 state emission as generally the terbium lifetimes
with no bound water molecules in the first coordination sphere range lie in the ms range. The
increase of the PL lifetime from 500 ꢂs at roomꢀtemperature to 1.3 ms (obtained also by single
exponential fitting, Figure 10b) at liquid nitrogen temperature confirmed the dominant
contribution of a temperatureꢀdependent vibrational quenching. It is acknowledged that strong
nonꢀradiative relaxation of the emitting state in TbIII complexes is activated via the backꢀenergy
5
transfer process from the D4 level of the metal to the triplet states of the ligand when the triplet
energy fall below ∼22,000 cmꢀ1.16 However, in some cases, the energy backꢀflow theory cannot
explain the reduction of the lifetimes for terbium complexes.17 Further, the singlet pathway of the
emission sensitization may also be effective, as proposed for several terbium(III) complexes with
Schiff base ligands.5aꢀb,6,18
[Zn(valampy)2Dy(O2NO)3]·CH3CN 12. In contrast with TbIII complex , the emission and
excitation spectra of DyIII complex are markedly different (Figures 11 and 10a) although the
lowest excited energy level (4F9/2) of DyIII is at ~480 nm, very close to the 5D4 level of TbIII . The
DyIII related emission is comparable with that of the ligand (around 450 nm) while the excitation
spectrum measured on the strongest emission at 574 nm contains relative strong contribution
from the fꢀf absorptions transitions of DyIII (Figure 11). By use of timeꢀresolved luminescence,
the characteristic emissions of DyIII are revealed at 485, 573, 658 and 748 nm corresponding to
the 4F9/2 ꢀ 6H15/2, 4F9/2 ꢀ 6H13/2, 4F9/2 ꢀ 6H11//2 and 4F9/2 ꢀ 6H9/2,6F11/2, respectively. Because the 4F9/2
ꢀ
4
6
6H11/2 and F9/2 ꢀ H13/2 transitions are considered to be of predominantly magnetic and electric
dipole character (with hypersensitivity property as ꢃJ = 2), respectively the intensity I(4F9/2
ꢀ
6
6H13/2)/I(4F9/2ꢀ H11/2) can be used as measure for the loss of centrosymmetry of the DyIII
coordination environment.19 The value of the ratio is 9.36 which is in line with the distorted
symmetry at DyIII sites found by Xꢀray analysis. Overall, the shapes of the emission/excitation
14

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spectra together with the relative short PL lifetime of ~ 1ꢂs, suggest that the antenna effect is
weak in complex 12.
[Zn(valampy)2Pr(O2NO)3]·CH3CN 8. PrIII is an attractive optical activator in view of the
possibility of simultaneous blue, green, and red emission for laser action as well as infrared
emission for optical amplification.20 The emission spectra and, especially, lifetimes of PrIII
complexes are, however, less studied compared to those of the Vis or NIR emitting LnIII
.
Excitation into the maximum of ligand absorption (λex = 390 nm) of the PrIII complex leads to
relative weak and narrow emission lines superimposed on broad ligand type emission peaked at
3
~ 430 nm. The emissions at 603 and 645 nm correspond to the 1D2 ꢀ H4 and 3P0ꢀ 3F2 transitions
of PrIII. Weaker emissions can be also observed within the range of 490ꢀ 500 nm, 520ꢀ555, and
3
3
3
3
1
3
670ꢀ 720 nm corresponding to the P0 ꢀ H4 , 3P0ꢀ H5 and (3P0 ꢀ F3 + D2 ꢀ H5), transitions of
1
PrIII, respectively (Figure 12, Spectrum 1). Because the D2 level exhibits the largest energy gap
to the next lower lying level (~6.500 cmꢀ1, relative to 1G4 compared to only ~ 3.500 cmꢀ1 for 3P0
1
1
relative to D2) generally, for PrIII complexes, the strongest emission originates form the D2
level. The excitation spectrum measured at λem = 603 nm displays a broad band with maximum
around 390 nm corresponding to the excitation through the ligand absorption on which several fꢀ
f absorptions of PrIII can be observed in the range of ~ 375 to 450 nm.
By using pulsed laser excitation (nitrogen laser, λex = 337 nm, pulse width of 3 ns), the
3
3
shortꢀlived ligand type emission is no longer detected. Also, the P0ꢀ F2 emission at 645 nm
observed with the steadyꢀstate emission is no longer detected (Spectrum 2, Figure 12). On the
3
basis of our instrumental total delay of ~35 ns, the lifetime of P0 level in complex 8 may be
1
roughly estimated in the ns range. It is generally considered that the strongest D2 emission
3
3
measured at 603 nm contains admixture from the P0ꢀ F2 emission.21 Comparison between the
timeꢀresolved and steadyꢀstate emission spectra show that the spectral feature at 610 nm (marked
3
3
3
with “*” on Figure 12) can be assigned to the shorterꢀlived P0 (via P0 ꢀ H6 transition)
1
3
emission. The PL decay corresponding to the D2 ꢀ H4 emission (λex = 337 nm, λem= 603 nm)
1
gives a lifetime value around 500 ns. Typical lifetimes of D2 level of PrIII complexes measured
in solution are quite short of the order of few hundreds of ns22 with a much higher value, of 11 ꢂs
being recently reported for a PrIII −organic frameworks.23
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Conclusions
This paper illustrates with new examples that, in the 3dꢀ4f combined chemistry, parallel
series of heterometallic complexes can be synthesized by changing the 3d metal ion. When the
3d ions are paramagnetic, the main interest arises from their magnetic properties, while the
[ZnLn] series are investigated because of their photoluminescence. Sixteen new binuclear
[ZnLn], [NiLn], [CuLn] complexes have been obtained using two nonꢀcompartmental ligands
derived from oꢀvanillin and 2ꢀaminomethyꢀpyridine and, respectively, 2ꢀ(2ꢀaminoethyl)ꢀ
pyridine. We observed subtle structural differences between the three families of complexes,
which arise from the stereochemical preference of the 3d metal ions. The CuIIꢀGdIII, NiIIꢀGdIII
and NiIIꢀHoIII exchange interactions were found to be ferromagnetic. The roomꢀtemperature
emission/excitation spectra and lifetimes of SmIII (9), EuIII (12), GdIII (10), TbIII (11), DyIII (12)
and PrIII (8) measured in the solid state evidence for the relative strong ligand to metal energy
transfer in 9 and 11. The increase of the emission lifetime of TbIII from 0.5 ms at roomꢀ
temperature to 1.3 ms at liquid nitrogen temperature evidences the manifestation of the back
transfer in the nonꢀradiative relaxation of TbIII emission in 11. Only weak sensitization of EuIII,
DyIII and PrIII emission was found in 13, 12 and 8.
Acknowledgment. This work was supported by a grant of the Romanian National Authority for
Scientific Research, CNCS – UEFISCDI, project number PNꢀIIꢀRUꢀTEꢀ2011ꢀ3ꢀ0252. CT
acknowledges partial support from COST CM1006 “EUFEN: European FꢀElement Network”.
Supporting Information Available:
properties of complex 10.
χMT curves for compounds 14 and 16; photophysical
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Soc., Dalton Trans., 1996, 961; (b) P. A. Guerriero, P. A. Vigato, J.ꢀC. G. Bünzli, E.
Moret, J. Chem. Soc., Dalton Trans., 1990, 647; (c) R. RodríguezꢀCortiñas, F. Avecilia,
C. PlatasꢀIglesias, D. Imbert, J.ꢀC.G. Bünzli, A. De Blas, T. RodríguezꢀBlas, Inorg.
Chem., 2002, 41, 5336.
19. S. Petoud, G. Muller, E. G. Moore, J. Xu, J. Sokolnicki, J. P. Riehl, U. Le, S. M. Cohen,
K. N. Raymond, J. Am. Chem. Soc., 2007, 129, 77.
20. F. Auzel, F. Chem. Rev., 2004, 104, 139.
21. A. I. Voloshin, N. M. Shavaleev, V. P. Kazakov, J. Lumin., 2001, 93, 199.
22. J. Scholten, G. A. Rosser, J. Wahsner, N. Alzakhem, C. Bischof, F. Stog, A. Beeby, M.
Seitz, J. Am. Chem. Soc., 2012,134, 13915.
23. R. Decadt, K. Van Hecke, D. Depla, K. Leus, D. Weinberger, I. Van Driessche, P. Van
Der Voort, R. Van Deun, Inorg. Chem., 2012 51, 11623.
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Table 1. Crystallographic data, details of data collection and structure refinement parameters for
compounds 1-7, 9-11, 13, 15, 16.
Compound
1
2
3
4
5
Chemical formula
M (g molꢀ1)
Temperature, (K)
Wavelength, (Å)
Crystal system
Space group
a(Å)
C32H33N8O13SmZn C32H35EuN8NiO14 C32H35GdN8NiO14 C32H35DyN8NiO14 C32H35HoN8NiO14
953.38
293(2)
966.35
293(2)
971.64
293(2)
976.89
293(2)
979.32
293(2)
0.71073
Monoclinic
P21/a
0.71073
Monoclinic
P21/n
0.71073
Monoclinic
P21/n
0.71073
Monoclinic
P21/n
0.71073
Monoclinic
P21/n
17.1501(5)
11.1874(9)
20.5208(11)
90
12.9132(5)
19.3730(6)
15.1871(6)
90
12.8862(5)
19.4017(6)
15.1766(6)
90
12.8557(5)
19.4086(7)
15.1631(7)
90
12.8478(5)
19.3966(6)
15.1553(5)
90
b(Å)
c(Å)
α(°)
105.596(4)
90
3792.3(4)
4
98.684(3)
90
3755.8(2)
4
1.709
2.234
98.747(3)
90
3750.2(2)
4
1.721
2.333
99.045(4)
90
3736.3(3)
4
1.737
2.566
98.995(3)
90
3730.3(2)
4
1.744
2.688
β
(°)
γ
(°)
V(Å3)
Z
Dc (g cmꢀ3)
1.670
2.239
1908
1.038
ꢀ (mmꢀ1)
F(000)
1944
0.900
0.0305, 0.0519
0.0547, 0.0563
1948
1.006
0.0395, 0.0575
0.0732, 0.0638
1956
1.002
0.0272, 0.0522
0.0420, 0.0560
1960
0.955
0.0296, 0.0496
0.0495, 0.0534
Goodnessꢀofꢀfit on F2
Final R1, wR2 [I>2σ(I)]
R1, wR2 (all data)
Largest diff. peak and
hole (eÅꢀ3)
0.0477, 0.1214
0.0689, 0.1292
1.660, ꢀ1.349
1.349, ꢀ0.578
0.508, ꢀ1.138
0.311, ꢀ1.052
1.057, ꢀ0.728
Compound
6
7
9
10
11
Chemical formula
M (g molꢀ1)
Temperature, (K)
Wavelength, (Å)
Crystal system
Space group
a(Å)
C32H33CuEuN8O13 C32H33CuGdN8O13 C30H29N8O13SmZn C30H29GdN8O13Zn C30H29N8O13TbZn
953.16
293(2)
958.45
293(2)
925.33
293(2)
932.23
293(2)
933.90
293(2)
0.71073
Monoclinic
P21/a
0.71073
Monoclinic
P21/a
0.71073
Monoclinic
C2/c
0.71073
Monoclinic
C2/c
0.71073
Monoclinic
C2/c
16.8588(7)
11.2386(3)
20.4501(10)
90
16.8607(6)
11.2122(4)
20.4234(7)
90
21.9810(8)
12.7911(3)
16.9394(7)
90
21.9113(18)
12.7257(7)
16.8798(15)
90
21.9564(15)
12.7382(5)
16.9246(13)
90
b(Å)
c(Å)
α(°)
104.911(4)
90
3744.2(3)
4
104.879(3)
90
3731.5(2)
4
130.558(2)
90
3618.5(2)
4
130.47(3)
90
3580.7(15)
4
130.408(5)
90
3604.4(4)
4
β
(°)
γ
(°)
V(Å3)
Z
Dc (g cmꢀ3)
1.691
2.302
1908
1.033
1.706
2.406
1912
1.038
1.699
2.344
1844
0.994
1.729
2.581
1852
0.935
1.721
2.686
1856
0.939
ꢀ (mmꢀ1)
F(000)
Goodnessꢀofꢀfit on F2
Final R1, wR2 [I>2σ(I)]
R1, wR2 (all data)
Largest diff. peak and
hole (eÅꢀ3)
0.0516, 0.1095
0.0845, 0.1202
0.0498, 0.1138
0.0881, 0.1257
0.0191, 0.0465
0.0232, 0.0476
0.0319, 0.0611
0.0446, 0.0635
0.0264, 0.0549
0.0362, 0.0568
0.916, ꢀ1.437
1.702, ꢀ1.388
0.430, ꢀ0.863
1.876, ꢀ1.797
0.764, ꢀ1.078
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Compound
13
15
16
Chemical formula
M (g molꢀ1)
Temperature, (K)
Wavelength, (Å)
Crystal system
Space group
a(Å)
C30H29EuN8O13Zn C28H34N7NiO17Sm C32H34EuN9NiO14
926.94
293(2)
949.68
293(2)
979.35
293(2)
0.71073
Monoclinic
C2/c
0.71073
Monoclinic
C2/n
0.71073
Triclinic
Pꢀ1
21.795(2)
12.7388(14)
16.8446(19)
90
130.612(6)
90
14.4975(8)
23.6838(16)
23.5318(16)
90
104.979(6)
90
12.966(2)
13.261(2)
13.785(2)
71.469(13)
67.302(13)
77.851(13)
2062.8(6)
2
b(Å)
c(Å)
α(°)
β
(°)
γ
(°)
V(Å3)
3550.3(7)
4
7805.2(9)
8
Z
Dc (g cmꢀ3)
1.734
1.616
1.577
ꢀ (mmꢀ1)
2.501
2.050
2.035
F(000)
1848
3816
984
Goodnessꢀofꢀfit on F2
Final R1, wR2 [I>2σ(I)]
R1, wR2 (all data)
Largest diff. peak and
hole (eÅꢀ3)
0.922
0.810
0.858
0.0339, 0.0762
0.0449, 0.0793
0.0308, 0.0505
0.0661, 0.0562
0.0651, 0.0954
0.1327, 0.1123
2.176, ꢀ1.151
0.653, ꢀ0.388
1.074, ꢀ1.015
Table 2. Selected bond distances for compounds 1-7, 9-11, 13, 15, and 16
5
Compound
Bond
1
2
3
4
Zn1ꢀO2 = 2.033(3)
Zn1ꢀO4 = 2.047(3)
Zn1ꢀN1 = 2.037(4)
Zn1ꢀN2 = 2.102(4)
Zn1ꢀN3 = 2.071(4)
Ni1ꢀN1 = 2.091(2)
Ni1ꢀN2 = 2.114(2)
Ni1ꢀN3 = 2.080(2)
Ni1ꢀ N4 = 2.113(2)
Ni1ꢀN1 = 2.0943(19)
Ni1ꢀN2 = 2.1164(19)
Ni1ꢀN3 = 2.0800(19)
Ni1ꢀN4 = 2.115(2)
Ni1ꢀN1 = 2.094(2)
Ni1ꢀN2 = 2.115(2)
Ni1ꢀN3 = 2.076(2)
Ni1ꢀN4 = 2.121(2)
Ni1ꢀO2 = 2.0902(16)
Ni1ꢀO4 = 2.1108(16)
Dy1ꢀO2 = 2.2738(16)
Dy1ꢀO4 = 2.3356(16)
Dy1ꢀO14 = 2.378(2)
Dy1ꢀO9 = 2.4334(19)
Dy1ꢀO11 = 2.439(2)
Dy1ꢀO8 = 2.477(2)
Dy1ꢀO5 = 2.4805(19)
Dy1ꢀO12 = 2.484(2)
Dy1ꢀO6 = 2.525(2)
Ni1ꢀN1 = 2.094(2)
Ni1ꢀN2 = 2.115(2)
Ni1ꢀN3 = 2.076(2)
Ni1ꢀN4 = 2.118(2)
Ni1ꢀO2 = 2.0910(17)
Ni1ꢀO4 = 2.1105(15)
Ho1ꢀO2 = 2.2668(16)
Ho1ꢀO4 = 2.3292(16)
Ho1ꢀO14 = 2.366(2)
Ho1ꢀO9 = 2.418(2)
Ho1ꢀO11 = 2.429(2)
Ho1ꢀO8 = 2.4654(18)
Ho1ꢀO5 = 2.4714(19)
Ho1ꢀO12 = 2.478(2)
Ho1ꢀO6 = 2.513(2)
length (Å)
Ni1ꢀO2 = 2.0862(16)
Ni1ꢀO4 = 2.1142(16)
Eu1ꢀO2 = 2.3082(16)
Eu1ꢀO4 = 2.3679(16)
Eu1ꢀO5 = 2.511(2)
Eu1ꢀO6 = 2.562(2)
Eu1ꢀO8 = 2.5069(18)
Eu1ꢀO9 = 2.474(2)
Eu1ꢀO11 = 2.479(2)
Eu1ꢀO12 = 2.510(2)
Eu1ꢀO14 = 2.422(2)
Ni1ꢀO2 = 2.0891(15)
Ni1ꢀO4 = 2.1133(15)
Gd1ꢀO2 = 2.3034(16)
Gd1ꢀO4 = 2.3636(14)
Gd1ꢀO5 = 2.5029(17)
Gd1ꢀO6 = 2.5471(18)
Gd1ꢀO8 = 2.5002(18)
Gd1ꢀO9 = 2.4612(18)
Gd1ꢀO11 = 2.470(2)
Gd1ꢀO12 = 2.499(2)
Gd1ꢀO14 = 2.408(2)
Sm1ꢀO2 = 2.409(3)
Sm1ꢀO4 = 2.312(3)
Sm1ꢀO12 = 2.474(5)
Sm1ꢀO6 = 2.488(5)
Sm1ꢀO5 = 2.500(5)
Sm1ꢀO9 = 2.519(4)
Sm1ꢀO11 = 2.542(5)
Sm1ꢀO8 = 2.565(5)
Sm1ꢀO1 = 2.544(3)
Sm1ꢀO3 = 2.900(4)
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Compound
6
7
9
10
Bond
Cu1ꢀO2 = 1.991(2)
Cu1ꢀO4 = 1.931(3)
Cu1ꢀN1 = 1.946(3)
Cu1ꢀN2 = 2.175(3)
Cu1ꢀN3 = 2.084(3)
Eu1ꢀO4 = 2.336(3)
Eu1ꢀO2 = 2.388(2)
Eu1ꢀO12 = 2.467(4)
Eu1ꢀO6 = 2.481(4)
Eu1ꢀO5 = 2.487(4)
Eu1ꢀO9 = 2.502(3)
Eu1ꢀO11 = 2.529(4)
Eu1ꢀO8 = 2.547(4)
Eu1ꢀO1 = 2.555(3)
Eu1ꢀO3 = 2.792(3)
Cu1ꢀO2 = 1.986(3)
Cu1ꢀO4 = 1.928(3)
Cu1ꢀN1 = 1.947(3)
Cu1ꢀN2 = 2.167(3)
Zn1ꢀN1 = 2.0603(14)
Zn1ꢀN2 = 2.3956(16)
Zn1ꢀO2 = 2.0504(10)
Zn1ꢀN1 = 2.056(3)
Zn1ꢀN2 = 2.393(2)
Zn1ꢀO2 = 2.0463(18)
length (Å)
Cu1ꢀN3 = 2.085(3)
Gd1ꢀO4 = 2.323(3)
Gd1ꢀO2 = 2.378(2)
Gd1ꢀO12 = 2.449(4)
Gd1ꢀO6 = 2.468(4)
Gd1ꢀO5 = 2.473(4)
Gd1ꢀO9 = 2.481(3)
Gd1ꢀO11 = 2.504(4)
Gd1ꢀO8 = 2.534(4)
Gd1ꢀO1 = 2.543(3)
Gd1ꢀO3 = 2.799(3)
Gd1ꢀO1 = 2.688(2)
Gd1ꢀO2 = 2.3264(17)
Gd1ꢀO5 = 2.508(2)
Gd1ꢀO7 = 2.491(3)
Gd1ꢀO9 = 2.472(2)
Sm1ꢀO1 = 2.7024(13)
Sm1ꢀO2 = 2.3551(10)
Sm1ꢀO5 = 2.5395(13)
Sm1ꢀO7 = 2.5189(15)
Sm1ꢀO9 = 2.5022(14)
Compound
Bond
11
13
15
16
Zn1ꢀN1 = 2.063(2)
Zn1ꢀN2 = 2.406(2)
Zn1ꢀO2 = 2.0517(15)
Zn1ꢀN1 = 2.068(3)
Zn1ꢀN2 = 2.376(3)
Zn1ꢀO2 = 2.057(3)
Ni1ꢀN1 = 2.112(3)
Ni1ꢀN2 = 2.032(2)
Ni1ꢀN3 = 2.120(3)
Ni1ꢀN4 = 2.026(3)
Ni1ꢀO2 = 2.063(2)
Ni1ꢀO3 = 2.081(2)
Sm1ꢀO2 = 2.434(2)
Sm1ꢀO3 = 2.401(2)
Sm1ꢀO5 = 2.564(3)
Sm1ꢀO6 = 2.567(2)
Sm1ꢀO8 = 2.566(2)
Sm1ꢀO9 = 2.582(3)
Sm1ꢀO11 = 2.551(3)
Sm1ꢀO12 = 2.627(3)
Sm1ꢀO14W = 2.460(2)
Ni1ꢀN1 = 2.029(8)
Ni1ꢀN2 = 2.099(8)
Ni1ꢀN3 = 2.019(8)
Ni1ꢀN4 = 2.114(10)
Ni1ꢀO2 = 2.076(7)
Ni1ꢀO4 = 2.119(8)
Eu1ꢀO2 = 2.335(8)
Eu1ꢀO4 = 2.381(7)
Eu1ꢀO5 = 2.502(8)
Eu1ꢀO6 = 2.508(8)
Eu1ꢀO8 = 2.564(7)
Eu1ꢀO9 = 2.559(7)
Eu1ꢀO11 = 2.520(10)
Eu1ꢀO12 = 2.521(9)
Eu1ꢀO14W = 2.418(7)
length (Å)
Tb1ꢀO1 = 2.6998(18)
Tb1ꢀO2 = 2.3172(15)
Tb1ꢀO5 = 2.500(2)
Eu1ꢀO1 = 2.695(3)
Eu1ꢀO2 = 2.345(3)
Eu1ꢀO5 = 2.536(3)
Eu1ꢀO7 = 2.502(3)
Eu1ꢀO9 = 2.489(3)
Tb1ꢀO7 = 2.4804(19)
Tb1ꢀO9 = 2.4616(18)
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CAPTION TO THE FIGURES
Figure 1. View of the molecular structure of [Zn(valaepy)2Sm(O2NO)3] in 1.
Figure 2. Perspective view of [Ni(valaepy)2Eu(O2NO)3(H2O)] in crystal 2.
Figure 3. View of the molecular structure of [Cu(valaepy)2Eu(O2NO)3] in crystal 6.
Figure 4. Molecular structure of [Zn(valampy)2Sm(O2NO)3] in crystal 9 (’ = ꢀx, y, 1.5ꢀz).
Figure 5. Perspective views of [Ni(valampy)2Sm(O2NO)3(H2O)2] in 15 (a) and
[Ni(valampy)2Eu(O2NO)3(H2O)] in 16 (b).
Figure 6.
χMT curves for compounds 3 (a) and 7 (b). The red solid lines represent the best fit to
the data. The insets: M vs. H plots at 2.0 K.
Figure 7. χMT curves for compounds 2 (a) , 4 (b), 5 (c), 15 (d).
Figure 8. (a) Excitation (λem = 597 nm) and emission spectra of complex 9 (λex = 390 nm); (b)
PL decay measured at λex = 390 nm and λem = 597 nm. Red line represents fitting results with
single exponential function.
Figure 9. Excitation (λem = 615 nm) and emission spectra of [Zn(valampy)2Eu(O2NO)3]·CH3CN
13 complex (pulsed laser excitation at λex = 464 nm, initial delay δt = 1 ꢂs). Red line represent
fitting results with single exponential function.
Figure 10. (a) Excitation (λem = 544 nm) and emission spectra of TbIII complex 11 (λex = 390
nm); (b) PL decays of TbIII complex measured at 80 and 300 K (λex= 390 nm; λem = 544 nm).
Red lines represent fitting results with single exponential function.
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Figure 11. Excitation (λem = 574 nm) and emission spectra of complex 12. Spectrum (1) is
measured under steadyꢀstate excitation at λex= 350 nm; spectrum (2) is measured under pulsed
laser excitation at λex = 390 nm, initial delay δt = 1ꢂs.
Figure 12. Excitation (λem = 603 nm) and emission spectra of the [ZnPr] complex, 8 (Spectrum 1
obtained under steadyꢀstate excitation at λe x= 390 nm; Spectrum 2 obtained under pulsed laser
excitation at λex = 337 nm and initial delay δt= 35 ns).
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Scheme 1
Figure 1
Figure 2
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Figure 3
Figure 4
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Figure 5
Figure 6
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Figure 7
100
10-1
*
250 300 350 400 450 500 550 600 650 700 750
0
50
100
150
200
Wavelength (nm)
time (ꢀs)
(a)
Figure 8
(b)
28