Synthesis, NMR, relaxometry and circularly polarised luminescence studies of macrocyclic monoamidetris(phosphinate) complexes bearing a remote chiral centre

Article abstract of DOI:10.1039/a708667i

Lanthanide complexes of macrocyclic monoamidetris(phosphinate) ligands are partially hydrated in aqueous solution. Introduction of a chiral centre into the amide group leads to the formation of only two non-interconverting complex diastereoisomers (2:1 for α-phenylethyl and 4:1 for α-1-naphthylethyl). Proton, ³¹P NMR and circularly polarised luminescence studies indicated that the configuration at the chiral carbon centre determines the helicity of the layout of the pendent arms and the macrocyclic ring conformation, with an RRR or SSS configuration preferred at the phosphorus centres.

Full text of DOI:10.1039/a708667i

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Synthesis, NMR, relaxometry and circularly polarised luminescence
studies of macrocyclic monoamidetris(phosphinate) complexes bearing
a remote chiral centre
Silvio Aime,c Mauro Botta,c Rachel S. Dickins,a Christine L. Maupin,b David Parker,*,†,a
James P. Riehlb and J. A. Gareth Williamsa
a Department of Chemistry, University of Durham, South Road, Durham, UK DH1 3LE
b Department of Chemistry, Michigan Technological University, Houghton, MI 49931-1295, USA
c Dipartimento di Chimica I. F. M., Universita degli Studi di Torino, via P. Giuria 7, Torino 10125,
Italy
Lanthanide complexes of macrocyclic monoamidetris(phosphinate) ligands are partially hydrated in aqueous
solution. Introduction of a chiral centre into the amide group leads to the formation of only two non-
interconverting complex diastereoisomers (2:1 for α-phenylethyl and 4:1 for α-1-naphthylethyl). Proton,
31P NMR and circularly polarised luminescence studies indicated that the configuration at the chiral carbon
centre determines the helicity of the layout of the pendent arms and the macrocyclic ring conformation, with
an RRR or SSS configuration preferred at the phosphorus centres.
At the outset of a project directed towards the study of
intramolecular stereoselective energy-transfer processes in
lanthanide complexes, it was necessary first to understand the
structural features which determine the relative energies of
suitable complex stereoisomers in aqueous solution. For such a
study, kinetically robust complexes are required that are
relatively static on the NMR time-scale and tri- or tetra-
N-substituted derivatives of 1,4,7,10-tetraazacyclododecane
(cyclen) are well suited for this purpose.1 Examples of such
ligands are the monoamidetris(phosphinates), e.g. L1c and L1d,
in which the four ring nitrogens and four pendent oxygens may
bind cooperatively to a lanthanide ion to give a well defined
complex.2 The Y and Gd complexes of such ligands are kinetic-
ally stable with respect to dissociation both in vitro (kobs is ca.
2 × 10Ϫ6 sϪ1 at pH 1, 310 K)3 and in vivo (>99.7% of the com-
plex is excreted intact over 7 d).4 In the complexes with Eu, Y
and Gd, it has been shown that one predominant stereoisomer
exists in aqueous solution (as a 50:50 mixture of enantiomers)
and partial, that is non-integral, hydration of the bound ion
occurs.2,5 The ligands examined to date in this series possess no
stereogenic centres at carbon. It was of interest to determine the
effect of introducing a chiral centre into the amide group exam-
ining the stereoisomerism in the derived lanthanide complexes.
An added impetus for this study came from the observation that
in the lanthanide complexes of enantiopure tetraamides,
greater than 99% of one relatively rigid enantiopure complex is
present in solution wherein the remote chiral centre at carbon
determines both the helicity of the four pendent amide ‘arms’
and the configuration of the 12[ane]N4 ring.6,7 Accordingly, we
have synthesised the chiral monoamidetris(phosphinate)
ligands, H3L1a, H3L1b and H3L2 and examined the aqueous solu-
tion behaviour of their Eu, Gd and Tb complexes by NMR,
luminescence and circularly polarised emission techniques.
alkylation of the molybdenumtricarbonyl complex of cyclen
with the α-chloroamides 3a, 3b, 3c or 4, followed by oxidative
deprotection yielded the monosubstituted derivatives 5a, 5b, 5c
and 6a respectively. Co-condensation of these secondary
amines with resublimed paraformaldehyde (CH2O)n in the pres-
ence of MeP(OEt)2 in dry THF led to phosphinoxymethylation
of the three ring nitrogens. Subsequent base hydrolysis (10%
aqueous KOH, 20 ЊC) gave the tris(phosphinates) L1a, L1b and
L2 and the lanthanide ion was introduced in water by reaction
with the appropriate lanthanide acetate salt.
Stereochemical and NMR analysis
In the lanthanide complexes of L1c and L1d, there are 32 pos-
sible stereoisomers, i.e. 16 pairs of enantiomers which are dis-
tinguishable by NMR spectroscopy in an achiral environment.2
These arise from three chiral elements: the R or S configuration
at each phosphorus, the left- or right-handed helicity defining
the lay-out of the four pendent arms and the overall ∆ or Λ
configuration of the 12[ane]N4 ring. The introduction of a
remote chiral centre in the amide moiety renders all 32 isomers
diastereoisomeric and therefore distinguishable in principle
by NMR spectroscopy. Prior work with an achiral amide sub-
stituent has revealed that one major diastereoisomer exists in
solution, as was deduced from 31P and 1H NMR spectroscopy,
and inspection at high-resolution of the emission band at
579.2 nm of the ∆J = 0 transition of the Eu complex.1,2
The europium complexes of L1a/1b and L2 were examined by
31P NMR spectroscopy in D2O (Fig. 1). Analysis of the spectra
revealed the presence of two major species (appearing as three
line singlets) and with [EuL2] at least three other minor species
can be discerned. The ratio of the major isomers is dependent
upon the steric bulk of the chiral amide group, being 2:1 for the
phenyl and 4:1 for the 1-naphthyl containing complexes.‡ Add-
ition of up to 5 equivalents of β-cyclodextrin to [EuL2] or
[EuL1a] caused a shifting in all of the 31P resonances but no
change in the number of resonances observed. On the other
Results and Discussion
Synthesis
‡ The complex [EuL1a] was analysed by analytical HPLC using a β-
cyclodextrin chiral column. Two species were observed in ratio 4:1 [275
K; t = 0 min (95% H2O, 5% MeOH), t = 25 min (100% MeOH)] using a
simple gradient, but the baseline separation (∆tR = 0.4 min) was insuffi-
cient to allow semi-preparative resolution.
The ligands and their lanthanide complexes were prepared
according to established procedures (Scheme 1).3,8,9 Mono-
† E-Mail: david.parker@durham.ac.uk
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892
881

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H
H
Me
P
H
H
R'
N
N
N
N
O
OH
H
R
R
H
N
NH2
N
N
N
N
HO
O
R'
Mo(CO)6, Bun2O,
reflux, Ar
ClCH2COCl, Et3N
Et2O, – 20 °C, Ar
P
Me
HO
P
O
O
H
O
H
R'
N
Me
H
N
H
Cl
N
R
N
(R)- H3L1a R = 1-C10H7, R' = Me
(S)- H3L1b R = Me, R' = 1-C10H7
H
N
Mo
H
OC
CO
H3L1c R = H, R' = 1-C10H7
H3L1d R = H, R' = H
OC
16
(i) DMF, K2CO3, 60 °C
(ii) aq. HCl, air, 20 °C
Me
H
R
N
O
P
OH
H
N
H
H
Me
N
N
N
N
H
O
N
N
N
R'
HO
O
Ph
H
N
P
Me
O
HO
P
O
(i) MeP(OEt)2, (CH2O)n, THF, reflux
(ii) KOH, H2O, 20 °C
Me
(S)-H3L2
(iii) Ln(OCOCH3)3, H2O, reflux
Me
P
O
O
H
R
N
Ph
O
R
O
N
N
N
N
Cl
Cl
O
Me
N
H
O
Ln
R'
R'
N
H
P
Me
(S)-4
O
O
P
(R)- 3a : R' = 1-C10H7, R = Me
(S)- 3b : R' = Me, R = 1-C10H7
3c : R = H, R' = 1-C10H7
O
Me
Ln = Eu, Gd or Tb
H
R
N
(R )-L1a R = 1-C10H7, R' = Me
(S )-L1b R = Me, R' = 1-C10H7
L1c R = H, R' = 1-C10H7
L1d R = H, R' = H
R"
N
N
N
N
O
R'
R"
R"
(S )-L2 R = Me, R' = Ph
Scheme 1
(R)- 5a : R = 1-C10H7, R' = Me, R" = H
(S)- 5b : R = Me, R' = 1-C10H7, R'' = H
5c : R" = R = H, R' = 1-C10H7
1
due to line-broadening.10,11 A partial analysis of the H᎐1H
COSY spectrum for [EuL2] was carried out (see Experimental
section for details). The presence of two major isomers was
confirmed and was most evident in the appearance of two sets
of P-Me doublets in ratio 2:1, consistent with the 31P NMR
5d : R = 1-C10H7, R' = Me, R" = CH2PMeO2Et
5e : R = Me, R' = 1-C10H7, R" = CH2PMeO2Et
5f : R = H, R' = 1-C10H7, R" = CH2PMeO2Et
H
Me
N
analysis. Variable-temperature H and 31P-{1H} NMR studies
1
R
of [EuL1a] were carried out in the range 290 to 363 K. The 31P
NMR study revealed a selective broadening of the resonances
due to the minor isomers: at 315 K they had broadened, where-
as the major resonances remained sharp (Fig. 2). At 333 K, the
resonances of the major isomers also begin to broaden, and at
363 K one set had overlapped but for the pair around δ 90/93
the shift non-equivalence was the same as it was at 248 K.
Allowing for the expected rather complex T dependence of the
31P NMR shift in Eu complexes, such behaviour is consistent
with exchange between the two major isomers and the other
minor isomers, but the two major isomers themselves are not in
rapid exchange with each other (on the NMR time-scale) over
this temperature range.
N
N
N
N
O
Ph
R
R
(S)-6a : R = H
6b : R = CH2PMeO2Et
hand, when 2 equivalents of β-cyclodextrin was added to
[EuL1c], the three resonances at δ 96.6, 84.4 and 67.4 associated
with the major isomer (≈90%), shifted and resolved to give three
pairs of resonances of equal intensity at δ 96.7, 96.5, 84.1, 83.2,
61.1 and 60.8. In this case, the β-cyclodextrin is acting as a
chiral solvating agent and is binding weakly to the enantiomers
of [EuL1c] to give two diastereoisomeric species.
The transverse relaxation times, T2, of the proton resonances
in [EuL1a/1b] and [EuL2] are sufficiently long to permit the detec-
tion of coupling patterns at low applied magnetic fields (e.g. 90
MHz), whereas at higher field this coupling information is lost
By comparison with reported12,13 crystal structures for the
La, Y, Eu, Gd and Yb complexes of a related tetra(benzyl-
phosphinate)–12[ane]N4 ligand (revealing an RRRR or SSSS
configuration at P), and by consideration of minimisation of
steric hindrance, it is most likely that in the observed major
882
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892

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Fig. 1 The 31P NMR spectra of [EuL2] (upper) and [EuL1a] (lower)
showing the formation of two major diastereoisomers in solution
(101.2 MHz, pD 5.5, 298 K)
Fig. 2 Variable-temperature 31P NMR spectra for [EuL1a] at 298, 315,
333 and 363 K (161.9 MHz, pD 5.5)
isomers of [EuL1a] and [EuL2], the complex adopts a twisted
square-antiprismatic structure and the P-Me groups are dir-
ected away from the 12[ane]N4 ring with an RRR or SSS con-
figuration at phosphorus. It is then evident that the observed
diastereoisomers will possess the same ring conformation and
lay-out of the pendent arms, but will differ only in the configur-
ation at phosphorus. The two major diastereoisomers of [EuL2]
that are observed are therefore likely to be (S-SSS) and
(S-RRR), specifying chirality at C and P in turn. Similarly
for [EuL1a] and [EuL1b], the observed diastereoisomers are
(R-RRR) and (R-SSS), and (S-SSS) and (S-RRR). Such an
analysis is consistent with the observation that 31P and 1H NMR
spectra for the 1-naphthyl containing Eu complexes were iden-
tical, could not be resolved by addition of β-cyclodextrin and
were not in exchange on the NMR time-scale. Interconversion
between the major pair of isomers would require cleavage of
the strong Ln᎐O bond (typically 2.4 Å),12 whereas exchange
between the minor isomers observed may occur by ring inver-
sion or by a pendent arm rotation.1,14 Such behaviour is then
consistent with the solution dynamics of related 12[ane]N4
complexes wherein a remarkable stability of the Ln᎐O bond,
with respect to dissociation, had been previously identified.15–17
its interpretation and representative data are given in several
recent references.1,12,15,18
Relaxivity values, R1p, (29 MHz, 298 K) of 3.65 and 3.45 dm3
mmolϪ1 sϪ1 were measured for [GdL2] and [GdL1a] respectively.
These values remained fairly constant over the pH range 2 to
12, only increasing slowly at pH < 2, as the onset of complex
dissociation led to the release of some of the free aquated Gd3ϩ
ion. The values are higher than those reported for the related
tetrabenzylphosphinate (R1p = 1.85 dm3 mmolϪ1 sϪ1) and
tetramethylphosphinate complexes (R1p = 2.44 dm3 mmolϪ1 sϪ1)
which are known to possess no bound water molecules.12 The
replacement of a phosphinate group by an amide binding site
allows a water molecule to approach the lanthanide more
closely, but may not lead to the water molecule being bound by
oxygen.2,5 Analysis of the NMRD profiles of [GdL2] and
[GdL1a] (Fig. 3 and Table 1), suggested that there was a
relatively long Gd᎐OH distance (3.40 and 3.44 Å respectively)
consistent with the presence of a well defined ‘second-sphere’
co-ordinated water.5,12 This second co-ordination sphere con-
tribution may result from the ability of the carboxamide oxygen
to act as a hydrogen-bond acceptor, thereby bringing the water
molecule sufficiently close to the paramagnetic centre to affect
the solvent relaxation (Scheme 2). Partial hydration of this type
has been reported previously in related complexes,2 and in this
case the water molecule approaches more closely to the Gd in
the less-encumbered complex [GdL2] (3.40 Å), compared to
[GdL1a] (3.44 Å).
Relaxation properties of gadolinium complexes
The relaxation rate of the water proton in the presence of
[GdL1a] and [GdL2] has been measured over a range of applied
magnetic fields, and at various temperatures. The value of
the measured relaxivity (the increment of the water proton
relaxation rate per unit concentration) and analysis of the
associated NMRD (magnetic field dependence of the relaxiv-
ity) profiles allows information to be deduced on the hydration
state and on the various correlation times associated with
solution relaxation. Details of the form of the analysis used,
Solution NMR studies had revealed that addition of
β-cyclodextrin to [EuL2] and [EuL1a] led to shifts in the 31P
NMR resonance of the non-equivalent P atoms. The strength
of the interaction with [GdL1a] may be evaluated by measuring
the dissociation constant, Kd, for the β-cyclodextrin complex
with [GdL1a] using the proton relaxation enhancement tech-
nique.19 This involves monitoring the increase in relaxivity, at a
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892
883

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absence of β-cyclodextrin), as a function of β-cyclodextrin con-
centration. Using the quadratic expression in equation (1),13
Table 1 The NMR relaxation parameters obtained by fitting the
experimental NMRD profiles of [GdL2] and [GdL1a]
1
ε* = ͩ ͪ
εb
[GdL2]
[GdL1a]
¹
2
Parametera
298 K
312 K
278 K
298 K
312 K
²
CT ϩ nMT ϩ Kd Ϫ [(CT ϩ nMT ϩ Kd) Ϫ 4nMTCT]
ϩ 1 (1)
2CT
τso/ps
τν/ps
τr/ps
τm/ns
122
18.3
100
0.9
1
3.40
4.0
91
9.1
61
0.5
1
3.40
4.0
3.15
118
24.4
190
1.3
1
3.44
4.0
1.0
124
15.7
91
0.8
1
3.44
4.0
2.4
113
8.4
60
0.6
1
3.44
4.0
3.15
wherein CT = total concentration of complex, MT = total β-
cyclodextrin concentration, n = 1 and εb = relaxivity of the
bound complex, a value for Kd of 2.6 × 10Ϫ2 dm3 molϪ1 was
obtained by an iterative best fitting procedure. This is a
relatively weak interaction in comparison to the dissociation
constant for β-cyclodextrin with 1-methylnaphthalene (Kd =
3.2 × 10Ϫ3 dm3 molϪ1, H2O, 298 K).20
q
r/Åb
a/Å
10Ϫ5 D/cm2 sϪ1
2.40
a τso is the electronic relaxation time at zero field, τν is the field-
independent correlation time, τm is the exchange rate for the proximate
water molecule and τr is the rotational correlation time for the complex;
q is the nearest integral hydration number and r is the mean proton Gd
distance; a is the mean distance of approach of ‘outer-sphere’ water
molecules and D is the diffusion coefficient of the complex. b Structural
analyses show that Gd᎐H distances are ca. 3.0 in q = 1 complexes and
>4.0 Å in q = 0 complexes.1
Luminescence behaviour of Eu and Tb complexes
The UV absorption spectra of [LnL2] and [LnL1a] revealed the
presence of a phenyl ππ* absorption at 254 nm (ε = 200 dm3
molϪ1 cmϪ1) and a naphthyl ππ* absorption band at 286 nm
(ε = 9300 dm3 molϪ1 cmϪ1). The aromatic chromophore serves
as a useful antenna group in these complexes allowing sensi-
tised emission of the proximate lanthanide to occur, following
intramolecular energy transfer.1 The metal-based emission life-
times and quantum yields were measured in H2O and D2O
(Table 2). As expected with the Eu complexes, quantum yields
were low due to efficient deactivation of the singlet excited state
involving a photoinduced electron transfer to the readily
reduced europium (Eu3ϩ/2ϩ = Ϫ0.35 V) centre. The [TbL1a] com-
plex also exhibited a weak emission in aereated aqueous solu-
tion, but a quantum yield of 0.1 was measured in deaereated
solution. This behaviour may be attributed to a competitive
thermally activated back energy transfer process from the emis-
5
sive D4 state to the naphthyl triplet. The naphthyl triplet is
quenched by molecular oxygen: removal of molecular oxygen
eliminates this deactivation pathway and strong emission is
then observed. The photophysical details of such processes
have recently been reported in analogous mononaphthyl2 and
tetranaphthyl tetraamide complexes.21,22
The lifetimes of the emissive state in H2O and D2O were
determined by observing the intensity of the luminescence after
a range of delay times (Table 2). The amide NH protons under-
go rapid exchange in D2O,22 so that comparison of the radiative
rate constants in H2O and D2O allows the effect of the quench-
ing amide NH and closely diffusing OH oscillators to be dis-
cerned. Recent analysis of over a dozen eight- and nine-co-
2,5,23
ordinate Eu complexes of 12[ane]N4
has shown that a
secondary amide NH oscillator contributes about 0.08 msϪ1 in
Fig. 3 The NMRD profiles at 298 and 312 K for [GdL2] (upper) and
[GdL1a] (lower). The solid line through the experimental points shows
the simulated behaviour using a best-fitting procedure to relaxation
theory. The lower curves show the outer-sphere contributions to the
observed relaxivity
terms of k [equation (2)] (knat is the natural radiative lifetime, knr
H2O
k
= knat ϩ knr ϩ ΣkXH ϩ ΣkC᎐O
(2)
obs
is the rate constant for non-radiative deactivation and ΣkXH
/
ΣkC᎐O is the sum of the rate constants for energy transfer to
N
proximate, energy matched XH or C᎐O oscillators). For ter-
᎐
bium complexes this amide NH quenching effect is much
smaller and may be ignored. A hydrophilic 12[ane]N4 Eu
complex gives rise to quenching of the Eu D0 state from the
–
O
+
HN
H
O
5
H
unbound, but closely diffusing OH oscillators.23 Again, anal-
ysis of >12 related complexes reveals that this effect contrib-
utes on average ca. 0.25 msϪ1 to the measured k value. After
allowing for these effects (Table 2), a corrected hydration
state, q, may be estimated. The values obtained reveal that
the Eu complexes examined are only partially hydrated (non-
integral values) with the naphthyl complex giving a lower q
value than the phenyl. The analogous Tb complexes are even
less hydrated. This pattern of behaviour has been observed
previously with ‘achiral’ monoamidetris(phosphinate) lan-
thanide complexes,2,5 and is consistent with the NMRD derived
distance parameter (Table 1), which was in an intermediate
R
H
Me
Scheme 2
fixed Larmor frequency, when a given concentration of the
gadolinium complex is titrated with increasing amounts of
β-cyclodextrin. On formation of the adduct, the molecular
volume of the gadolinium complex is increased, leading to a
slower rotational correlation time, τR, and an associated
increase in relaxivity. The titration data were handled as a plot
of the relaxivity enhancement factor, ε* (representing the ratio
of the paramagnetic relaxation rates in the presence and
884
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892

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Table 2 Luminescence lifetimes and observed radiative rate constants for the europium and terbium complexes in H2O and D2O and their use in
estimating the hydration state of the metal
1c
Complexa,d
τH O/ms
τD O/ms
kH O/msϪ1
kD O/msϪ1
∆kc/msϪ1
ΣOH
q
corr
osϩNH
2
2
2
2
[EuL1d]b
0.76
0.68
0.73
3.20
3.00
1.85
1.74
1.70
4.30
4.00
1.32
1.47
1.37
0.31
0.33
0.54
0.57
0.59
0.23
0.25
0.78
0.90
0.78
0.08
0.08
Ϫ0.33
Ϫ0.33
Ϫ0.33
Ϫ0.06
Ϫ0.06
0.56
0.71
0.56
0.1
[EuL2]
[EuL1a]
[TbL1d]b
[TbL2]
0.1
a Quantum yields for [EuL2] were 1 × 10Ϫ3 and 2 × 10Ϫ3 in H2O and D2O respectively, for [TbL2] 0.12 and 0.18 and for [EuL1a] 0.8 × 10Ϫ3 (H2O) and
1c
1.7 × 10Ϫ3 (D2O). b Data from refs. 2, 5. c Values of q
for Eu complexes were obtained by subtracting 0.08 msϪ1 from ∆k to compensate for the
corr
amide NH quenching, and 0.25 msϪ1 to allow for quenching by ‘outer-sphere’ (unbound) OH oscillators. Using q = AЈ∆k (AЈ is an empirically
derived proportionality constant reflecting the sensitivity of the given lanthanide to quenching by OH oscillators); for Eu, AЈ = 1.25. For the Tb
complexes, a correction of 0.06 msϪ1 was applied to allow for ‘outer-sphere’ OH quenching only. Full details of this modified method of analysis will
be reported subsequently. d For complexes of L2 and L1d, excitation was at 254 nm; for the complex of L1a, at 290 nm.
range between that found for a metal-bound water and a
purely ‘outer-sphere’ hydrated complex. The lower hydration
of the Tb complexes has now been seen consistently in many
12[ane]N4 complexes, and is also apparent in aqua ion chem-
istry. The change in co-ordination number of hydrated ions
(‘the gadolinium break’) halfway along the ‘f’-block series is
well known despite the small (2.4 pm) difference in ionic
radius between Eu and Tb.24
solution have the same macrocyclic ring conformation and
pendent arm helicities, and differ only in the configuration at
the P centres. Such a conclusion accords with the interpretation
of the NMR data, discussed earlier.
Conclusion
In the Eu and Tb complexes of L2 and L1a/1b, NMR and CPL
measurements strongly indicate that the configuration of the
chiral centre in the amide group determines the helicity of the
pendent arms and probably the macrocyclic ring conformation.
The complexes exist in solution as two non-interconverting
diastereoisomers, differing only in the configuration at P (RRR
or SSS), in a ratio which is dependent on the size of the remote
chiral group.
Circularly polarised luminescence
Circularly polarised luminescence (CPL) is the emission
analogue of circular dichroism, and may be used to probe the
chiral environment of the lanthanide excited state.25–27 The
5
total emission and CPL spectra associated with the D4 →
7F5|7F4|7F3 transitions, following direct laser excitation of the
7F6 → 5D4 transition in [TbL2] at 488 nm were measured in
water (Fig. 4). The measured emission dissymmetry factors,
gem, were quite large and measured ϩ0.17 (∆J = Ϫ1, 543 nm),
Ϫ0.06 (∆J = 0, 584 nm) and Ϫ0.12 (∆J = ϩ1, 621 nm) for
the observed transitions. The CPL spectra obtained were in-
dependent of the nature of the excitation: identical CPL spectra
were obtained with left- or right-handed circularly polarised
light. Although there may, in theory, be preferential absorption
of left- or right-handed CP light, the circularly polarised
emission is independent of the handedness of the excitation
source. It is the chirality (helicity) about the metal centre that
determines the sign and magnitude of the CPL.
Experimental
General procedures and characterisation techniques
Reactions requiring anhydrous or inert conditions were carried
out using Schlenk-line techniques under an atmosphere of dry
argon. Anhydrous solvents when required were freshly distilled
over the appropriate drying agent. Water was purified by the
‘PuriteSTILLplus’ system.
Thin layer chromatography was carried out on neutral alu-
mina plates (Merck Art 5550) or silica plates (Merck 5554) and
detection was made following irradiation at 254 nm or by stain-
ing with iodine. Column chromatography was carried out using
neutral alumina (Merck Aluminium Oxide 90, activity II-III,
70-230 mesh) pre-soaked in ethyl acetate, or silica (Merck Silica
Gel 60, 230-400 mesh). Analytical and semi-preparative HPLC
were performed on a Varian 9010/9065 Polychrom system using
a chiral cyclodextrin column (Shodex OR pak CDB-853 HQ
series, β-cyclodextrin) and a flow rate of 1.4 cm3 minϪ1
(T = 2 ЊC; t = 0 min, 95% H2O, 5% MeOH; t = 25 min, 100%
MeOH, end time).
Melting points were measured with a Köfler block and are
uncorrected. Infrared spectra were recorded on a Perkin-Elmer
1600 FT spectrometer with GRAMS Analyst software, and
a Graseby-Specac ‘Golden Gate’ Diamond ATR accessory
spectrometer. Oils were examined as thin films and solids
incorporated into KBr discs as stated.
The NMR spectra were acquired using a Brüker AC250
spectrometer operating at 250.13, 62.9, 101.1 and 235.3 MHz
for 1H, 13C-{1H}, 31P-{1H} and 19F-{1H} measurements respec-
tively; a Varian VXR 200 operating at 200 MHz for 1H; a JEOL
EX-90 operating at 90 and 36 MHz for 1H and 31P-{1H} respec-
tively; a JEOL EX-400 operating at 400, 100.6 and 161.8 MHz
for 1H, 13C-{1H} and 31P-{1H} respectively and a Varian
VXR400 operating at 400 MHz for 1H. Two-dimensional
spectra were run on a JEOL EX-90 and a Varian VXR 200
spectrometer. Variable-temperature 1H NMR studies were car-
ried out on a Varian VXR 400; a JEOL EX-90 and a JEOL
Strong CPL was also observed with [TbL1a] in degassed
aqueous solution either following direct laser excitation or
indirect excitation into the proximate naphthyl chromophore
(λex = 300 nm) (Fig. 5). The CPL spectra obtained with [TbL1a]
were remarkably similar to those obtained with [TbL2]. The
values of gem (ϩ0.18 for ∆J = Ϫ1 at 540 nm) were essentially the
same and were independent of the mode of excitation. The
similarity of behaviour between the two complexes is not par-
ticularly surprising, since the complexes only differ in the aryl
substituent in the amide moiety.
Proton and 31P NMR studies on the corresponding Eu com-
plexes had revealed that two diastereoisomers are not
exchanging and exist in solution in a ratio of 2:1 for [LnL2] and
4:1 for [LnL1a]. If the diastereoisomers have identical ring con-
formations and the same layout of the pendent arms, then the
observed CPL will be due to contributions from both isomers.
On the other hand, if the two diastereoisomers have enantio-
meric ring conformations and pendent arm helicities, then equal
and opposite CPL spectra will be observed for each isomer: the
CPL from the major isomer would then cancel out the contri-
bution to the CPL from the minor isomer, so the measured CPL
is due to the diastereoisomer in excess. As the ratio of the major
to minor isomer is greater for [TbL1a], then a larger gem value
might have been anticipated compared to [TbL2]. The fact that
the observed dissymmetry values and CPL spectra were almost
identical, strongly suggests that the two diastereoisomers in
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892
885

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Fig. 4 (a) Total emission spectrum for [TbL2]. Total emission spectrum (lower) and circularly polarised luminescence (CPL) spectrum (upper)
showing (b) the ∆J = Ϫ1 (gem = ϩ0.17), (c) ∆J = 0 (gem = Ϫ0.06) and (d) ∆J = ϩ1 (gem = Ϫ0.12) transitions following excitation at 488 nm (pH
5.5, 298 K). The solid and dotted lines for the ∆J = ϩ1 transition show the CPL spectrum obtained with left- or right-handed circularly polarised
excitation
EX-400 instruments. Proton relaxivities were measured at 25 ЊC
on a 20 MHz Spin-Master spectrometer (Stelar) by means of
the inversion recovery technique. Proton and 13C-{1H} spectra
were referenced internally relative to tert-butyl alcohol (1 drop;
δH 0; δC 31.3) for paramagnetic complexes or to the residual
protio-solvent resonances which are reported relative to SiMe4.
The 31P-{1H} spectra were referenced externally relative to
H3PO4 in D2O (δ 0).
Electrospray mass spectra were recorded on a VG Platform II
(Fisons instrument) operating in positive or negative ion mode
as stated. The FAB and accurate mass spectra were recorded by
the EPSRC Mass Spectrometry Service at Swansea.
Luminescence and absorption spectra
Ultraviolet absorbance spectra were recorded on a Unicam
UV/VIS spectrometer UV2-100 with Unicam Vision Software
Version 2.11. Fluorescence spectra were recorded on a Perkin-
Mass spectra were recorded on a VG 7070E spectrometer
operating in DCI (ammonia) or FAB (glycerol matrix) mode.
886
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892

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the Eu3ϩ (560–581 nm) was accomplished by using a Coherent-
599 tunable dye laser (0.03 nm resolution) using the argon-ion
laser as a pump source. The laser dye used in the measurement
was Rhodamine 110 in ethylene glycol. Calibration of the
emission monochromator (and subsequently the dye laser)
was accomplished by passing scattered light from a low power
He–Ne laser through the detection system. The error in the dye
laser wavelength was assumed to be equal to the resolution of
the emission detection. The optical detection system consisted
of a photoelastic modulator (PEM, Hinds Int.) operating at
50 kHz, and a linear polariser which together act as a circular
analyser, followed by a long pass filter, focusing lens, and a 0.22
nm monochromator. The emitted light was detected by a cooled
EM1-9558QB photomultiplier tube operating in photon count-
ing mode. The output pulses from the photomultiplier tube
were passed through a variable gain amplifier/discriminator and
input into a specially built differential photon counter. The 50
kHz reference signal from the photoelastic modulator was used
to direct the incoming pulses into two separate counters, an up-
counter which counts every photon pulse and thus is a measure
of the total luminescence signal I = Ileft ϩ Iright, and an up/down
counter which adds pulses when the analyser is transmitting
left circularly polarised light and subtracts when the analyser
is transmitting right circularly polarised light. This second
counter provides a measure of the differential emission in-
tensity ∆I = Ileft Ϫ Iright. The differential photon counter allows
for the selection of a time window for counting which is
centred around the maximum in the modulation cycle. For the
measurements reported here, the window was set to 50%.
Fig. 5 Total emission spectrum (lower) and circularly polarised
luminescence spectrum (upper) for [TbL1a], showing the ∆J = Ϫ1
(
540 = ϩ0.18) transition following UV excitation of the naphthyl
gem
chromophore (298 K degassed, H2O)
Elmer LS50B spectrofluorimeter using FL Winlab Version 1.10
software, equipped with a Hamamatsu R928 photomultiplier
tube using quartz fluorescence cuvettes of pathlength 1 cm.
Phosphorescence emission and excitation spectra were
recorded on the same instrument operating in time-resolved
mode with a delay time of 0.1 ms and a gate time of 10 ms.
Emission spectra were corrected for the wavelength dependence
of the photomultiplier tube and the most highly resolved
spectra were obtained with slit widths (half-height bandwidth)
of 10 nm (excitation) and 2.5 nm (emission). The spectrometer
automatically corrects the phosphorescence excitation spectra
through a reference photomultiplier tube and the spectra were
obtained by monitoring the emission at 590 or 619 nm for Eu3ϩ
and 545 nm for Tb3ϩ complexes.
Ligand synthesis
2-Chloro-N-[(S)-methylbenzyl]ethanamide (S)-2.
O
Ph Me
Cl
H
N
H
Chloroacetyl chloride (0.78 cm3, 9.9 mmol) in dry diethyl ether
(20 cm3) was added dropwise to a stirred solution of (S)-α-
methylbenzylamine (1.1 cm3, 8.3 mmol) and triethylamine (1.4
cm3, 9.9 mmol) in dry diethyl ether (30 cm3) at Ϫ20 ЊC. The
reaction mixture was allowed to warm to room temperature and
stirred for 1 h. The resulting white precipitate was dissolved in
water (60 cm3) and the organic layer washed with hydrochloric
acid (0.1 mol dmϪ3, 50 cm3), water (3 × 30 cm3), dried (K2CO3)
and the solvent removed in vacuo to yield a white solid.
Recrystallisation from diethyl ether yielded white needles
(0.95 g, 60%); m.p. 95–96 ЊC; νmax(KBr)/cmϪ1 3265 (N᎐H),
Luminescence quantum yields, φ, were measured according
to the procedure described by Haas and Stein,28 using [Ru(2,2Ј-
bipy)]2ϩ (φ = 0.028 in H2O)29 and quinine sulfate (φ = 0.546 in
0.5 mol dmϪ3 H2SO4)30 as standards for Eu3ϩ and Tb3ϩ com-
plexes respectively.
Lifetimes were measured on a Perkin-Elmer LS50B spectro-
fluorimeter using software written for this purpose by Dr.
A. Beeby, University of Durham. Reported lifetimes, τ, are the
average of at least three separate measurements calculated by
monitoring the emission intensity at 590 or 619 nm for Eu3ϩ
and 545 nm for Tb3ϩ complexes after at least 20 different delay
times covering two or more lifetimes. The gate time was 0.1 ms
and slit widths of 15 nm and 5 nm or less were employed for
Eu3ϩ and Tb3ϩ complexes respectively. The phosphorescence
decay curves were fitted by an equation of the form I(t) = I(0)
exp(Ϫt/τ) using a curve fitting program (Kaleidagraph software
on an Apple Macintosh or Grafit software on a PC), where I(t)
is the intensity at time t after the excitation flash, I(0) the initial
intensity at t = 0 and τ is the phosphorescence lifetime. High
correlation coefficients were observed, τ is reproducible to at
least 0.06 ms and independent of concentration over the range
examined (solution absorbance 0.05–0.5).
1652 (C᎐O); δ (250 MHz; CDCl ) 7.41–7.34 (5 H, m, C H ),
᎐
H
3
6
5
6.82 (1 H, br s, NH), 5.18 (1 H, m, CH), 4.11 (1 H, d, 2J 15.1,
CH2), 4.08 (1 H, d, 2J 15.1, CH2), 1.58 (3 H, d, 3J 6.7 Hz, CH3);
δC{1H} (62.9 MHz; CDCl3) 165.0 (CO), 142.4 (q-C6H5), 128.8
(m-C6H5), 127.6 (p-C6H5), 126.1 (o-C6H5), 49.2 (CHN), 42.6
(CH2), 21.7 (CH3); m/z (DCI) 198 (100%, Mϩ) (Found: C,
60.6; H, 6.15; N, 6.90. C10H12ClNO requires C, 60.8; H, 6.12;
N, 7.08%).
2-Chloro-N-[(R)-1-naphthyl]ethylethanamide (R)-3a.
O
Me C10H7
Cl
H
N
H
This compound was prepared following a method similar to
that for compound 2 using (R)-1-(1-naphthyl)ethylamine
(0.94 cm3, 5.8 mmol) and triethylamine (0.98 cm3, 7 mmol)
in dry diethyl ether (30 cm3) and treating with a solution of
chloroacetyl chloride (0.56 cm3, 7 mmol) in dry diethyl ether
Circularly polarised luminescence spectra were recorded at
Michigan Technological University, USA. Excitation of the
7F6 → 5D4 transition of Tb3ϩ was accomplished with the 488
nm line of a Coherent Innova 70 argon-ion laser. Excitation of
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892
887

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(30 cm3). The product was recrystallised from diethyl ether and
1-[(R)-1-(1-Naphthyl)ethylcarbamoylmethyl]-1,4,7,10-tetra-
was isolated as white needles (1.1 g, 76%); m.p. 144–145 ЊC;
azacyclododecane (R)-5a.
νmax(KBr)/cmϪ1 3296 (N᎐H), 1648 (C᎐O); δ (250 MHz; CDCl )
᎐
H
3
H
8.12–7.48 (7 H, m, C10H7), 6.84 (1 H, br s, NH), 5.99 (1 H, m,
H
N
H
N
2
2
CH), 4.13 (1 H, d, J 15.3, CH2), 4.11 (1 H, d, J 15.3, CH2),
1.75 (3 H, d, 3J 7.0 Hz, CH3); δC{1H} (62.9 MHz; CDCl3) 165.0
(CO), 137.5 (C10H7), 133.9 (C10H7), 130.9 (C10H7), 128.9
(C10H7), 128.6 (C10H7), 126.8 (C10H7), 126.0 (C10H7), 125.3
(C10H7), 123.1 (C10H7), 122.6 (C10H7), 45.2 (CH), 42.6 (CH2),
20.9 (CH3); m/z (DCI) 248 (100%, MHϩ), 212 (18%, Mϩ Ϫ Cl),
155 (70%, Mϩ Ϫ NHCOCl) (Found: C, 68.1; H, 5.64; N, 5.59.
C14H14ClON requires C, 67.8; H, 5.69; N, 5.65%).
N
N
H7C10 Me
O
N
H
H
This compound was prepared following a similar method to
that for compound 6a using 1,4,7,10-tetraazacyclododecane–
molybdenum–tricarbonyl complex (1 g, 2.86 mmol), 2-chloro-
N-[(R)-1-naphthyl]ethylethanamide 3a (0.71 g, 2.86 mmol) and
potassium carbonate (0.55 g, 4.0 mmol) in degassed, dry
dimethylformamide (30 cm3) to yield a brown oil (0.55 g, 50%)
2-Chloro-N-[(S)-1-naphthyl]ethylethanamide (S)-3b.
O
H7C10 Me
after purification; νmax(film)/cmϪ1 3421 (N᎐H), 1643 (C᎐O);
᎐
3
Cl
δH(250 MHz; CDCl3) 8.52 (1 H, d, J 8.0, NHCO), 8.12–7.49
(7 H, m, C10H7), 5.95 (1 H, m, CH), 3.25 (1 H, d, J 17.5,
CH2CO), 3.19 (1 H, d, J 17.5, CH2CO), 2.59–2.20 (19 H, m,
H
N
2
H
2
ring-CH2, ring-NH), 1.71 (3 H, d, 3J 6.9 Hz, CH3); δC{1H} (62.9
MHz; CDCl3), 170.6 (CO), 138.2 (q-C10H7), 133.6 (q-C10H7),
131.2 (q-C10H7), 128.6 (C10H7), 128.0 (C10H7), 126.4 (C10H7),
125.8 (C10H7), 125.2 (C10H7), 123.5 (C10H7), 122.9 (C10H7), 58.9
(CH2CO), 53.4 (ring-CH2), 46.8 (ring-CH2), 45.6 (ring-CH2),
44.5 (ring-CH2), 43.9 (CHN), 20.0 (CH3); m/z (DCI) 384
(100%, MHϩ).
This compound was prepared following a method similar to
that for compound 2 using (S)-1-(1-naphthyl)ethylamine (4.72
cm3, 29.2 mmol) and triethylamine (4.9 cm3, 35.1 mmol) in dry
diethyl ether (100 cm3) and treating with a solution of chloro-
acetyl chloride (2.79 cm3, 35.1 mmol) in dry diethyl ether (50
cm3). The product was recrystallised from diethyl ether and was
isolated as white needles (3.5 g, 48%). Characterisation data are
the same as those reported for 3a (Found: C, 68.0; H, 5.60; N,
5.54. C14H14ClON requires C, 67.8; H, 5.69; N, 5.65%).
1-[(S)-1-(1-Naphthyl)ethylcarbamoylmethyl]-1,4,7,10-tetra-
azacyclododecane (S)-5b.
1-[(S)-1-(1-Phenyl)ethylcarbamoylmethyl]-1,4,7,10-tetraaza-
cyclododecane (S)-6a.
H
H
N
H
N
N
N
N
H
H
N
Me
C10H7
O
H
N
N
N
N
Ph
Me
H
H
O
This compound was prepared following a similar method to
that for compound 6a using 1,4,7,10-tetraazacyclododecane–
molybdenum–tricarbonyl complex (4.2 g, 12.1 mmol), 2-chloro-
N-[(S)-1-naphthyl]ethylethanamide 3b (3.0 g, 12.1 mmol) and
potassium carbonate (2.34 g, 17 mmol) in degassed, dry
dimethylformamide (60 cm3) to yield a brown oil (2.3 g, 50%)
after purification. Characterisation data are the same as those
reported for (R)-5a.
H
H
1,4,7,10-Tetraazacyclododecane (0.4 g, 2.3 mmol) and molyb-
denum hexacarbonyl (0.6 g, 2.3 mmol) in dry dibutyl ether (20
cm3) were heated at reflux under argon for 2 h to give a bright
yellow precipitate of the 1,4,7,10-tetraazacyclododecane–
molybdenum–tricarbonyl complex (16) which was filtered
under argon and dried in vacuo. The complex (16) (0.8 g, 2.3
mmol) and fine mesh anhyhdrous potassium carbonate (0.4 g,
2.8 mmol) were taken into degassed dimethylformamide (30
cm3) and a solution of 2-chloro-N-[(S)-methylbenzyl]ethan-
amide 2 (0.45 g, 2.3 mmol) in dry dimethylformamide (1 cm3)
was added under argon by steel cannula. The reaction mixture
was heated at 60 ЊC for 4 h under an argon atmosphere. The
solvent was removed by distillation in vacuo and the brown
residue was taken into hydrochloric acid (1 mol dmϪ3, 13 cm3)
and the resulting acidic brown suspension was stirred open to
the air for 18 h. Molybdenum residues were removed by centri-
fugation and filtration and the aqueous layer was washed with
dichloromethane (30 cm3) and chloroform (20 cm3). The pH of
the solution was raised to 14 by addition of sodium hydroxide
pellets, with cooling. The product was extracted into dichloro-
methane (3 × 30 cm3), washed with water (3 × 30 cm3), dried
(K2CO3) and the solvent removed in vacuo to yield a yellow-
brown oil (620 mg, 81%); Rf (Al2O3; 10% CH3OH–CH2Cl2; I2
1-[(1-Naphthyl)methylcarbamoylmethyl]-1,4,7,10-tetraaza-
cyclododecane 5c.
H
C10H7
N
H
N
N
N
N
O
H
H
This compound was prepared following a method similar to
that for compound 6a using 1,4,7,10-tetraazacyclododecane–
molybdenum–tricarbonyl complex (0.75 g, 2.14 mmol), 2-
chloro-N-(naphthylmethyl)ethanamide5 (0.5 g, 2.14 mmol) and
potassium carbonate (0.35 g, 2.57 mmol) in degassed, dry
dimethylformamide (30 cm3) to yield a yellow oil (0.2 g, 25%)
after purification; νmax(film)/cmϪ1 3365 (N᎐H), 1652 (C᎐O);
᎐
and UV detection) 0.44–0.1; νmax(film)cmϪ1 3285 (N᎐H), 1666
δH(250 MHz; CDCl3) 8.50–8.40 (1 H, br m, NHCO), 7.82–7.76
(4 H, m, C10H7), 7.48–7.41 (3 H, m, C10H7), 4.61 (2 H, d, 3J 5.0,
CH2C10H7), 3.24 (2 H, s, CH2CO), 2.69–2.39 (19 H, m, ring-
CH2, ring-NH); δC{1H} (62.9 MHz; CDCl3) 171.3 (CO), 135.9
(C10H7), 133.0 (C10H7), 132.3 (C10H7), 128.1 (C10H7), 127.5
(C10H7), 127.4 (C10H7), 126.4 (C10H7), 126.2 (C10H7), 126.1
(C10H7), 125.7 (C10H7), 59.1 (CH2CO), 53.1 (ring-CH2), 46.9
(ring-CH2), 46.3 (ring-CH2), 45.6 (ring-CH2), 43.1 (CH2C10H7);
m/z (DCI) 370 (100%, MHϩ).
3
(C᎐O); δ (250 MHz; CDCl ) 8.23 (1 H, d, J 7.7, NHCO),
᎐
H
3
7.45–7.28 (5 H, m, C6H5), 5.21 (1 H, m, CH), 3.20 (2 H, s, CH2),
2.92–2.54 (16 H, m, ring-CH2), 2.00–1.90 (3 H, m, ring-NH),
1.56 (3 H, d, 3J 5.0 Hz, CH3); δC{1H} (62.9 MHz; CDCl3) 170.3
(CO), 143.3 (q-C6H5), 128.2 (m-C6H5), 126.8 (p-C6H5), 126.1
(o-C6H5), 58.8 (CH2CO), 52.9 (ring-CH2), 48.0 (CHN), 46.7
(ring-CH2), 46.4 (ring-CH2), 45.3 (ring-CH2), 21.3 (CH3); m/z
(DCI) 334 (100%, Mϩ).
888
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892

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Methyldiethoxyphosphine. Diethylchlorophosphite (14.3 cm3,
0.1 mol) was added dropwise, over 1 h, to a cooled solution of
methylmagnesium bromide (33.3 cm3 of a 3 mol dmϪ3 solution
in diethyl ether, 0.1 mol) under argon at 20 ЊC. The mixture
was allowed to warm to room temperature and stirred for 1 h.
The resulting precipitate was filtered off under argon by
cannula transfer. Distillation under reduced pressure yielded
methyldiethoxyphosphine as a solution in diethyl ether whose
molarity was established by addition of a known mass of
diethylphenylphosphonite followed by 31P NMR integration of
the two distinct singlets, δP{1H} (101.3 MHz) 176.4. On other
occasions this compound was purchased from Strem Chemicals
and used as received, following 31P analysis.
νmax(film)/cmϪ1 3397 (br) (N᎐H), 1652 (C᎐O); δ (250 MHz;
᎐
H
CDCl3) 8.45–7.47 (7 H, m, C10H7), 5.93 (1 H, m, CH), 3.99
(6 H, m, CH2CH3), 3.19–2.32 (24 H, br m, ring-CH2, CH2P,
CH2CO), 1.54 (9 H, d, 2J 13.0 Hz, PCH3), 1.37–1.28 (12 H, m,
CH2CH3, CH3); δC{1H} (62.9 MHz; CDCl3) 170.3 (CO), 138.5
(q-C10H7), 133.7 (q-C10H7), 131.5 (q-C10H7), 128.5 (C10H7), 128.1
(C10H7), 126.4 (C10H7), 125.8 (C10H7), 125.0 (C10H7), 123.7
(C10H7), 123.0 (C10H7), 60.0 (CH2CH3), 55.7–53.0 (ring-CH2,
CH2CO), 43.6 (CHN), 20.1 (CH3), 16.6 (CH2CH3), 13.7 (d,
1J 89 Hz, PCH3); δP{1H} (101.3 MHz; CDCl3) 53.3–51.4 (3 P, br
m); m/z (DCI) 744 (100%, MHϩ).
Triethyl 10-[(S)-1-(1-naphthyl)ethylcarbamoylmethyl]-1,4,7,
10-tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinate) 5e.
Triethyl 10-[(S)-1-(1-phenyl)ethylcarbamoylmethyl]-1,4,7,10-
tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinate) 6b.
O
P
OEt
H
Me
H
N
O
N
N
C10H7
P
OEt
H
Me
O
Me
H
N
EtO
O
N
N
P
N
N
Ph
Me
O
Me
Me
EtO
O
EtO
P
N
N
P
O
Me
Me
EtO
P
This compound was prepared following a method similar to
that for compound 5d using the monosubstituted macrocycle
5b (2.0 g, 5.2 mmol), methyldiethoxyphosphine (77 cm3 of
a 0.3 mol dmϪ3 solution in diethyl ether, 23.6 mmol) and
paraformaldehyde (0.8 g, 26.2 mmol) in dry tetrahydrofuran
(100 cm3) to yield a yellow oil (2 g, 52%) after purification.
Characterisation data are the same as those reported for 5d.
O
The monosubstituted macrocycle 6a (0.56 g, 1.68 mmol) was
allowed to heat at reflux temperature in dry tetrahydrofuran (40
cm3), under argon over 4 Å molecular sieves for 30 min. Methyl-
diethoxyphosphine (26.3 cm3 of a 1.1 mol dmϪ3 solution in
diethyl ether, 7.56 mmol) was added to the cooled solution.
After heating for 10 min at reflux, paraformaldehyde (0.25 g,
8.4 mmol) was added and the solution was heated at reflux for a
further 18 h. The solvent was removed in vacuo to yield a brown
oil. The product was purified by alumina column chrom-
atography (gradient elution from dichloromethane to 2%
methanol–dichloromethane) giving a yellow oil (0.6 g, 55%); Rf
(Al2O3; 10% MeOH–CH2Cl2; I2 and UV detection) 0.61;
νmax(film)/cmϪ1 3384 (br) (N᎐H), 1665 (C᎐O); δ (250 MHz;
Triethyl 10-[(1-naphthyl)methylcarbamoylmethyl]-1,4,7,10-
tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinate) 5f.
O
P
OEt
H
C10H7
Me
N
N
N
᎐
H
O
CDCl3) 8.15 (1 H, 3J 8.2, NH), 7.32–7.18 (5 H, m, C6H5), 5.12
(1 H, m, CH), 4.03–3.94 (6 H, m, CH2CH3), 3.11–2.48 (24 H, br
m, CH2CO, CH2P, ring-CH2), 1.50–1.36 (12 H, m, PCH3, CH3),
EtO
N
N
P
O
Me
Me
EtO
P
3
1.25 (9 H, t, J 7.0 Hz, CH2CH3); δC{1H} (62.9 MHz; CDCl3)
O
170.2 (CO), 143.5 (q-C6H5), 128.2 (m-C6H5), 126.9 (p-C6H5),
126.4 (o-C6H5), 59.9 (CH2CH3), 55.4 (ring-CH2), 53.9 (d, 3J 88,
CH2P), 47.9 (CHN), 21.3 (CH3), 16.5 (CH2CH3), 13.6 (d, 1J 89
Hz, PCH3); δP{1H} (101.3 MHz; CDCl3) 52.0 (3 P, br); m/z
(DCI) 694 (100%, Mϩ).
This compound was prepared following a method similar to
that for compound 5d using the monosubstituted macrocycle 5c
(0.2 g, 0.55 mmol), methyldiethoxyphosphine, (26.7 cm3 of a
0.09 mol dmϪ3 solution in diethyl ether, 2.46 mmol) and para-
formaldehyde (0.08 g, 2.73 mmol) in dry tetrahydrofuran (30
cm3) to yield a yellow oil (0.1 g, 29%) after purification; Rf
(Al2O3; 10% CH3OH–CH2Cl2; I2 and UV detection) 0.57;
δH(250 MHz; CDCl3) 8.70 (1 H, s, NH), 7.89–7.86 (4 H, m,
C10H7), 7.55–7.52 (3 H, m, C10H7), 4.73 (2 H, d, 3J 6.8,
CH2C10H7), 4.04 (6 H, m, CH2CH3), 3.29 (2 H, s, CH2CO),
3.10–2.46 (22 H, ring-CH2, CH2P), 1.50–1.30 (18 H, m, PCH3,
CH2CH3); δC{1H} (62.9 MHz; CDCl3) 171.5 (CO), 136.7
(q-C10H7), 133.3 (q-C10H7), 132.6 (q-C10H7), 128.2 (C10H7),
127.6 (C10H7), 126.6 (C10H7), 126.3 (C10H7), 125.8 (C10H7),
60.1 (CH2CH3), 55.5–53.3 (ring-CH2, CH2P, C H2CO), 43.2
Triethyl 10-[(R)-1-(1-naphthyl)ethylcarbamoylmethyl]-1,4,7,
10-tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinate) 5d.
O
P
OEt
H
Me
H
N
N
N
Me
H7C10
O
EtO
O
N
N
P
Me
Me
1
(CH2
N), 16.7 (CH CH ), 13.9 (d, J 88 Hz, PCH ); δ {1H}
EtO
P
2
3
3
P
(101.3 MHz; CDCl3) 52.5 (1 P), 52.2 (1 P), 52.1 (1 P). (A
satisfactory accurate mass spectrum could not be obtained for
this product.)
O
This compound was prepared following a method similar to
that for compound 6b using the monosubstituted macrocycle
5a (0.16 g, 0.42 mmol), methyldiethoxyphosphine (18) (6.5 cm3
of a 1.1 mol dmϪ3 solution in diethyl ether, 1.9 mmol) and
paraformaldehyde (0.06 g, 2.1 mmol) in dry tetrahydrofuran (20
cm3) to yield a yellow oil (0.17 g, 54%) after purification; Rf
(Al2O3; 10% CH3OH–CH2Cl2; I2 and UV detection) 0.68;
10-[(S)-1-(1-Phenyl)ethylcarbamoylmethyl]-1,4,7,10-
tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinic acid) L2.
The monoamidetris(phosphinate ester) 6b (0.3 g, 0.4 mmol) was
stirred in a solution of potassium hydroxide (10 cm3 of a 10%
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892
889

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ester) 5e (0.65 g, 0.87 mmol) in a solution of potassium hydrox-
O
ide (10 cm3 of a 10% solution in water) to give a pale yellow
solid (0.53 g, 92%). Characterisation data are the same as those
reported for L1a (Found: MNaϩ, 682.2662. C28H48N5NaO7P3
requires MNaϩ, 682.2664).
P
OH
HO
H
H
Me
N
Ph
N
N
N
Me
O
HO
N
P
O
10-[(1-Naphthyl)methylcarbamoylmethyl]-1,4,7,10-
tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinic acid) L1c.
Me
Me
P
O
solution in water) at room temperature for 18 h. The solution
was neutralised to pH 6.5 with hydrochloric acid (0.1 mol dmϪ3
solution) and the solvent removed by lyophilization. The result-
ing solid was dissolved in hot ethanol (5 cm3) and the remaining
salts removed by centrifugation followed by filtration. The sol-
vent was removed in vacuo to give a pale yellow solid (0.2 g,
82%); m.p. >200 ЊC; νmax(solid)/cmϪ1 3288 (br) (N᎐H), 1639
O
P
OH
H
C10H7
Me
N
N
N
N
O
HO
N
P
O
Me
Me
(C᎐O); δ (250 MHz; D O) 8.09 (1 H, s, NH), 7.07–6.97 (5 H,
HO
P
᎐
H
2
m, C6H5), 4.58 (1 H, m, CH), 3.33–2.14 (24 H, br m, ring-CH2,
CH2P, CH2CO), 1.11 (3 H, d, 3J 6.8, CH3), 0.95 (9 H, d, 2J 13.0
Hz, PCH3); δC{1H} (62.9 MHz; D2O) 171.1 (CO), 143.5
(q-C6H5), 128.7 (m-C6H5), 127.3 (p-C6H5), 125.7 (o-C6H5),
55.0–47.0 (ring-CH2, CH2CO, CH2P, CHN), 21.2 (CH3), 16.6
(d, 1J 91 Hz, PCH3); δP{1H} (101.3 MHz; D2O) 40.0–28.6 (3 P,
br); m/z (FAB) 610 (100%, MHϩ) (Found: MHϩ, 610.2689.
C24H47N5O7P3 requires MHϩ, 610.2688).
O
This compound was prepared following a method similar to
that for compound L1b using monoamidetris(phosphinate ester)
5f (0.1 g, 0.16 mmol) in a solution of potassium hydroxide (10
cm3 of a 10% solution in water) to give a pale yellow solid (0.07
g, 67%); m.p. >200 ЊC; νmax(solid)/cmϪ1 3291 (br) (N᎐H), 1644
(C᎐O); δ (250 MHz; D O) 7.60–7.16 (7 H, br m, C H ), 4.22
᎐
H
2
10
7
(2 H, s, CH2C10H7), 3.23–2.59 (24 H, br m, ring-CH2, CH2CO,
CH2P), 0.88 (9 H, d, J 13.4 Hz, PCH3); δC{1H} (62.9 MHz;
2
10-[(R)-1-(1-Naphthyl)ethylcarbamoylmethyl]-1,4,7,10-
tetraazacyclododecane-1,4,7-triyltrimethylenetri(methyl-
phosphinic acid) L1a.
D2O) 172.1 (CO), 135.5 (q-C10H7), 132.8 (q-C10H7), 132.2
(q-C10H7), 128.3 (C10H7), 127.5 (C10H7), 126.5 (C10H7), 126.1
(C10H7), 125.7 (C10H7), 56.4 (CH2CO), 54.2–50.5 (ring-CH2,
1
CH2P), 43.0 (CH2N), 16.9 (d, J 96 Hz, PCH3); δP{1H} (101.3
O
MHz; D2O) 39.4 (2 P), 33.0 (1 P); m/z (ESϪ) 645 (100%, M). (A
satisfactory accurate mass spectrum could not be obtained for
this product.)
P
OH
H
N
H
Me
Me
N
N
N
H7C10
O
HO
N
Lanthanide complexes
[EuL2].
P
O
Me
Me
HO
P
O
O
P
O –
H
H
This compound was prepared following a method similar to
that for compound L2 using the monoamidetris(phosphinate
ester) 5d (0.16 g, 0.2 mmol) in a solution of potassium hydrox-
ide (10 cm3 of a 10% solution in water) to give a pale yellow
solid (0.13 g, 92%); m.p. >200 ЊC; νmax(solid)/cmϪ1 3243 (N᎐H),
Me
N
Ph
N
N
N
Me
O
Eu3+
O –
N
P
O
Me
Me
1652 (C᎐O); δ (250 MHz; D O) 7.80–7.10 (7 H, m, C H ), 5.36
– O
P
᎐
H
2
10
7
(1 H, m, CH), 3.30–2.00 (24 H, br m, ring-CH2, CH2P,
O
3
CH2CO), 1.20 (3 H, d, J 6.7 Hz, CH3), 0.93–0.79 (9 H, br m,
PCH3); δC{1H} (62.9 MHz; D2O) 170.1 (CO), 138.6 (q-C10H7),
133.4 (q-C10H7), 130.0 (q-C10H7), 127.3–123.8 (C10H7), 121.3
(C10H7), 53.7–45.0 (br m, CH2P, ring-CH2, CHN, CH2CO),
20.0–15.0 (br m, CH3, PCH3); δP{1H} (101.3 MHz; D2O)
39.6–27.0 (3 P, br m); m/z (FAB) 660 (100%, MHϩ) (Found:
MHϩ, 660.2850. C28H49N5O7P3 requires MHϩ, 660.2844).
Europium() acetate (0.05 g, 0.14 mmol) was added to a stirred
solution of compound 2 (0.07 g, 0.12 mmol) in water (3 cm3)
and the solution was heated at reflux for 18 h. The solvent was
removed by lyophilization and the resulting solid extracted into
hot ethanol (4 cm3). The remaining salts were removed by centri-
fugation followed by filtration and the solvent removed in vacuo
to give a yellow-brown solid. Purification by column chrom-
atography through a plug of alumina (5% CH3OH–CH2Cl2)
yielded a very pale yellow solid (0.02 g, 22%); m.p. >250 ЊC; Rf
(Al2O3; 15% CH3OH–CH2Cl2; I2 detection) 0.4 (br); νmax(solid)/
10-[(S)-1-(1-Naphthyl)ethylcarbamoylmethyl]-1,4,7,10-
tetraazacyclododecane-1,4,7-triyltrimethlenetri(methyl-
phosphinic acid) L1b.
cmϪ1 3314 (br) (N᎐H), 1620 (C᎐O); m/z (ESϪ) 758.05 (100%, M)
᎐
O
(Found: MHϩ, 760.1663. C24H44EuN5O7P3 requires MHϩ,
760.1666). Major isomer: δH(90 MHz; D2O; 291 K) [partial
assignment] 28.2 (1 H, br, ring-Hax), 25.1 (1 H, br, ring-Hax),
17.2 (1 H, br, ring-Hax), 13.7 (1 H, br, ring-Hax), 9.5 (1 H, br,
ring-Hax), 6.8–5.9 (5 H, m, C6H5), 2.1 (3 H, d, 3J 6.2, CH3), 1.6
P
OH
H
H
Me
N
C10H7
N
N
N
Me
O
HO
N
2
P
to Ϫ0.7 (3 H, br, ring-Heq), Ϫ1.5 (3 H, d, J 16, PCH3), Ϫ3.8
O
Me
2
Me
(3 H, d, J 14, PCH3), Ϫ4.5 to Ϫ5.9 (2 H, br, ring-Hax), Ϫ6.4
HO
P
(3 H, d, 2J 14 Hz, PCH3), Ϫ6.9 to Ϫ7.8 (2 H, br, ring-Heq), Ϫ10.8
to Ϫ11.5 (2 H, br, ring-Hax, ring-Heq), Ϫ14.5 to Ϫ15.3 (2 H, br,
ring-Heq); δC{1H} (62.9 MHz; D2O) 200.9 (CO), 146.3 (q-C6H5),
128.7 (m-C6H5), 127.0 (p-C6H5), 125.5 (o-C6H5), 107.4–60.0
O
This compound was prepared following a method similar to
that for compound L1a using the monoamidetris(phosphinate
890
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892

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(ring-CH2, CH2P, C H2CO), 52.6 (CHN), 24.8 (CH3), 6.8–2.1
(PCH3); δP{1H} (101.3 MHz; D2O) 95.5 (1 P), 83.3 (1 P), 68.2
(1 P). Minor isomer: δH(90 MHz; D2O; 18 K) [partial assign-
ment] 27.6 (1 H, br, ring-Hax), 25.1 (1 H, br, ring-Hax), 17.2 (1 H,
br, ring-Hax), 13.7 (1 H, br, ring-Hax), 11.0 (1 H, br, ring-Hax),
6.8–5.9 (5 H, m, C6H5), 1.8 to Ϫ0.5 (3 H, br, ring-Heq), 1.3 (3 H,
d, 3J 6.3, CH3), Ϫ0.3 (3 H, d, 2J 14, PCH3), Ϫ4.4 (3 H, d, 2J 14,
PCH3), Ϫ5.9 (3 H, d, 2J 16 Hz, PCH3), Ϫ7.6 to Ϫ15.5 (8 H, br, 3
ring-Hax, 5 ring-Heq); δC{1H} (62.9 MHz; D2O) 202.6 (CO),
134–125 (C6H5), 107.4–60.0 (ring-CH2, CH2P, C H2CO), 53.7
(CHN), 23.3 (CH3), 6.8–2.1 (PCH3); δP{1H} (101.3 MHz; D2O),
97.3 (1 P), 79.0 (1 P), 64.6 (1 P).
[EuL1c].
O
P
O –
H
C
10H7
Me
N
N
N
O
Eu3+
O –
N
N
P
O
Me
Me
– O
P
O
This compound was prepared using a method similar to that for
complex [EuL2] using europium() acetate (0.047 g, 0.14
mmol) and compound L1c (0.055 g, 0.1 mmol) in water (3 cm3)
to yield a pale yellow solid (0.028 g, 41%); m.p. >250 ЊC; Rf
(Al2O3; 10% CH3OH–CH2Cl2; I2 detection) 0.74–0.34; δH(90
MHz; D2O; 301 K) [partial assignment] 27.7 (1 H, br, ring-Hax),
24.6 (1 H, br, ring-Hax), 17.1 (1 H, br, ring-Hax), 12.9 (1 H, br,
ring-Hax), 9.41 (1 H, br, ring-Hax), 8.44–6.58 (5 H, m, C10H7),
1.71 to Ϫ0.51 (3 H, br, ring-Heq), Ϫ1.20 (3 H, d, 2J 14, PCH3),
[EuL1a].
O
P
O –
H
N
H
Me
Me
N
N
Eu3+
H7C10
O
O –
N
N
2
P
Ϫ3.62 (3 H, d, J 14, PCH3), Ϫ4.42 (1 H, br, ring-Hax), Ϫ5.93
O
Me
2
Me
– O
P
(3 H, d, J 14 Hz, PCH3), Ϫ6.01 to Ϫ7.4 (3 H, br, ring-Hax,
2-ring-Heq), Ϫ10.0 to Ϫ14.1 (4 H, br, ring-Hax, 3 ring-Heq);
δC{1H} (400 MHz; D2O; 298 K) 203.5 (CO), 140.5 (q-C10H7),
137.0 (q-C10H7), 135.0 (q-C10H7), 131.5 (C10H7), 130.5 (C10H7),
130.0 (C10H7), 129.0 (C10H7), 128.5 (C10H7), 128.0 (C10H7),
127.5 (C10H7), 108.0 (ring-CH2), 106.0 (ring-CH2), 104.0 (ring-
O
This compound was prepared following a method similar to
that for [EuL2] using europium() acetate (0.012 g, 0.13 mmol)
and compound L1a (0.06 g, 0.09 mmol) in water (3 cm3) to yield a
pale yellow solid (0.034 g, 46%); m.p. >250 ЊC; Rf (Al2O3; 15%
CH3OH–CH2Cl2; I2 detection) 0.35 (br); vmax(solid)/cmϪ1 3256
1
CH2), 86.0 (ring-CH2), 85.0 (d, J 90, CH2P), 82.0 (ring-CH2),
72.5 (ring-CH2), 69.5 (d, 1J 90, PCH2), 68.5 (ring-CH2,
CH2CO), 63.0 (d, 1J 90, PCH2), 48.0 (CH2C10H7), 7.5 (d, 1J 90,
(br) (N᎐H), 1620 (C᎐O); m/z (ESϪ) 808 (100%, M) (Found:
᎐
1
1
PCH3), 6.5 (d, J 90, PCH3), 4.5 (d, J 90 Hz, PCH3); δP{1H}
(101.3 MHz; D2O) 96.6 (1 P), 84.4 (1 P), 67.4 (1 P); m/z (ESϪ)
794 (100%, M) (Found: C, 36.3; H, 6.42; N, 7.40. C23H43-
EuN5O7P3ؒ5H2O requires: C, 36.6; H, 5.99; N, 7.91%).
MHϩ, 810.1783. C28H45EuN5O7P3 requires MHϩ, 810.1822).
Major isomer: δH(90 MHz; D2O; 278 K) [partial assignment]
28.7 (1 H, br, ring-Hax), 25.7 (1 H, br, ring-Hax), 17.6 (1 H, br,
ring-Hax), 2.2 (3 H, d, 3J 6.6, CH3), Ϫ2.3 (3 H, d, 2J 14.7, PCH3),
Ϫ4.0 (3 H, d, 2J 15.5, PCH3), Ϫ6.6 (3 H, d, 2J 15.5 Hz, PCH3);
δC{1H} (400 MHz; D2O; 278 K) 227 (CO), 145 (q-C10H7), 136
(q-C10H7), 135 (q-C10H7), 131 (C10H7), 130 (C10H7), 129 (C10H7),
128 (C10H7), 127 (C10H7), 125 (C10H7), 122 (C10H7), 134–127
(ring-CH2, CH2P, C H2CO), 52 (CHN), 25 (CH3), 8–4 (PCH3);
δP{1H} (101.3 MHz; D2O) 96.0 (1 P), 82.3 (1 P), 66.8 (1 P).
Minor isomer: δH(90 MHz; D2O; 278 K) [partial assignment]
29.1 (1 H, br, ring-Hax), 27.5 (1 H, br, ring-Hax), 15.1 (1 H, br,
[GdL2].
O
P
O –
H
H
Me
N
Ph
N
N
Gd3+
Me
O
O –
3
2
N
N
P
ring-Hax), 1.77 (1 H, d, J 5.9, CH3), Ϫ3.4 (3 H, d, J 15.5,
PCH3), Ϫ5.1 (3 H, d, 2J 15.5, PCH3), Ϫ6.4 (1 H, d, 2J 15.5 Hz,
PCH3); δC{1H} (400 MHz; D2O; 298 K) 250 (CO), 147
(q-C10H7), 141 (q-C10H7), 138 (q-C10H7), 134–127 (C10H7), 110–
65 (ring-CH2, CH2P, C H2CO), 53 (CHN), 24 (CH3), 8–4
(PCH3); δP{1H} (101.3 MHz; D2O) 97.9 (1 P), 80.3 (1 P), 66.0
(1 P).
O
Me
Me
– O
P
O
This compound was prepared following a method similar to
that for complex [EuL2] using gadolinium() acetate (0.046 g,
0.14 mmol) and compound L2 (0.06 g, 0.1 mmol) in water (3
cm3) to yield a colourless solid (0.02 g, 26%); m.p. >250 ЊC; Rf
(Al2O3; 15% CH3OH–CH2Cl2; I2 detection) 0.60 (br);
[EuL1b].
νmax(solid)/cmϪ1 3300 (br) (N᎐H), 1620 (C᎐O); m/z (ESϪ) 762
᎐
O
(100%, M) (Found: M, 764.1621. C24H43GdN5O7P3 requires M,
764.1616).
P
O –
H
H
C
Me
N
[GdL1a].
10H7
N
N
Me
O
Eu3+
O –
N
N
O
P
O
O –
Me
P
Me
H
H
C
– O
P
Me
N
O
10H7
N
N
Me
O
Gd3+
O –
This compound was prepared following a method similar to
that for complex [EuL2] using europium() acetate (0.2 g, 0.3
mmol) and compound L1b (0.2 g, 0.3 mmol) in water (3 cm3) to
yield a pale yellow solid (0.13 g, 53%). Characterisation data
are the same as those reported for [EuL1a] (Found: MHϩ,
810.1843. C28H45EuN5O7P3 requires MHϩ, 810.1822) (Found:
C, 37.0; H, 6.46; N, 7.35%. C28H45EuN5O7P3ؒ5H2O requires: C,
37.4; H, 6.12; N, 7.78%).
N
N
P
O
Me
Me
– O
P
O
This compound was prepared following a method similar to
that for complex [EuL2] using gadolinium() acetate (0.049 g,
0.15 mmol) and compound L1a (0.07 g, 0.1 mmol) in water
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892
891

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(3 cm3) to yield a colourless solid (0.02 g, 25%), m.p. >250 ЊC;
Rf (Al2O3; 15% CH3OH–CH2Cl2; I2 detection) 0.42 (br); m/z
(ESϪ) 812 (100%, M). (A satisfactory accurate mass spectrum
could not be obtained for this product.)
Acknowledgements
We thank Durham University, the Royal Society and EPSRC
for grant support.
[TbL2].
References
1 D. Parker and J. A. G. Williams, J. Chem. Soc., Dalton Trans., 1996,
3613.
2 S. Aime, M. Botta, D. Parker and J. A. G. Williams, J. Chem. Soc.,
Dalton Trans., 1995, 2259.
3 K. P. Pulukkody, T. J. Norman, D. Parker, L. Royle and C. J. Broan,
J. Chem. Soc., Perkin Trans. 2, 1993, 605.
4 A. Harrison, T. J. Norman, D. Parker, L. Royle, K. A. Pereira, K. P.
Pulukkody and C. A. Walker, Magn. Reson. Imaging, 1993, 11, 761.
5 S. Aime, M. Botta, D. Parker and J. A. G. Williams, J. Chem. Soc.,
Dalton Trans., 1996, 17.
6 R. S. Dickins, J. A. K. Howard, C. W. Lehmann,. J. Moloney,
D. Parker and R. D. Peacock, Angew. Chem., Int. Ed. Engl., 1997,
521.
7 R. S. Dickins, J. A. K. Howard, J. Moloney, D. Parker, R. D.
Peacock and G. Siligardi, Chem. Commun., 1997, 1747.
8 J.-J. Yaouanc, N. Le Bris, G. Le Gall, J.-C. Clement, H. Handel and
H. des Abbayes, J. Chem. Soc., Chem. Commun., 1991, 206.
9 E. Cole, C. J. Broan, K. J. Jankowski, P. K. Pulukkody, D. Parker,
A. T. Millican, N. R. A. Beeley, K. Millar and B. A. Boyce,
Synthesis, 1992, 67.
10 I. Bertini and C. Luchinat, NMR of Paramagnetic Molecules in
Biological Systems, Benjamin-Cummings, Boston, MA, 1986.
11 T. J. Swift, in NMR of Paramagnetic Molecules: Principles and
Applications, eds. G. N. LaMar, W. De W. Horrocks and R. H.
Holm, Academic Press, London, 1973.
O
P
O –
H
H
Me
N
Ph
N
N
N
Me
O
Tb3+
O –
N
P
O
Me
Me
– O
P
O
This compound was prepared following a method similar to
that of complex [EuL2] using terbium() acetate (0.05 g, 0.14
mmol) and compound 2 (0.06 g, 0.1 mmol) in water (3 cm3) to
yield a pale yellow solid (0.03 g, 40%); m.p. >250 ЊC; Rf (Al2O3;
15% CH3OH–CH2Cl2; I2 detection) 0.4 (br); νmax(solid)/cmϪ1
3333 (br) (N᎐H), 1620 (C᎐O); δ {1H} (101.3 MHz; D O) 631
᎐
P
2
(br), 607 (br), 599 (br), 495 (br), 455 (br); m/z (ESϪ) 764 (100%,
M) (Found: MHϩ, 766.1707. C24H44N5O7P3Tb requires MHϩ,
766.1707).
[TbL1a].
12 S. Aime, A. S. Batsanov, M. Botta, R. S. Dickins, S. Faulkner,
C. E. Foster, A. Harrison, J. A. K. Howard, J. M. Moloney, T. J.
Norman, D. Parker, L. Royle and J. A. G. Williams, J. Chem. Soc.,
Dalton Trans., 1997, 3623.
O
P
O –
H
N
H
Me
13 S. Aime, A. S. Batsanov, M. Botta, J. A. K. Howard, D. Parker,
P. K. Senanayake and J. A. G. Williams, Inorg. Chem., 1994, 33,
4696.
14 S. Aime, M. Botta and G. Ermondi, Inorg. Chem., 1992, 32, 4296.
15 S. Aime, M. Botta, M. Fasano and E. Terreno, Chem. Soc. Rev.,
1998, 27, 19; R. B. Lauffer, Chem. Rev., 1987, 87, 901.
16 J. F. Desreux, Inorg. Chem., 1980, 19, 1319; X. Wang, T. Jin,
V. Comblin, A. Lopez-Mut, E. Merciny and J. F. Desreux, Inorg.
Chem., 1992, 31, 1095.
17 J.-P. Dubost, M. Leger, M. H. Langlois, D. Meyer and M. C.
Schaefer, C. R. Acad. Sci., Ser. 2, 1991, 312, 349.
18 J. A. Peters, J. Huskens and D. J. Raber, Prog. Nucl. Magn. Reson.
Spectrosc., 1996, 18, 283.
Me
N
N
N
H7C10
O
Tb3+
O –
N
P
O
Me
Me
– O
P
O
This compound was prepared following a method similar to
that for complex [EuL2] using terbium() acetate (0.043 g, 0.13
mmol) and compound L1a (0.06 g, 0.09 mmol) in water (3 cm3)
to yield a pale yellow solid (0.03 g, 40%); m.p. >250 ЊC; Rf
(Al2O3; 15% CH3OH–CH2Cl2; I2 detection) 0.51 (br); νmax
-
19 S. Aime, M. Botta, M. Grandi, M. Panero and F. Uggeri, Magn.
Reson. Chem., 1991, 29, 293.
(solid)/cmϪ1 3333 (br) (N᎐H), 1614 (C᎐O); δ {1H} (101.3 MHz;
᎐
P
D2O) 663 (br), 619 (br), 609 (br), 487 (br), 450 (br); m/z (ESϪ)
814 (100%, M) (Found: MHϩ, 816.1862. C28H46N5O7P3Tb
requires MHϩ, 816.1863).
20 K. A. Connors, in Comprehensive Supramolecular Chemistry, eds.
J. L. Atwood, J. E. D. Davies, D. D. MacNicol, F. Vogtle and
J.-M. Lehn, Pergamon, Oxford, 1996, vol. 3, ch. 6.
21 A. Beeby, D. Parker and J. A. G. Williams, J. Chem. Soc., Perkin
Trans. 2, 1996, 1165; D. Parker and J. A. G. Williams, J. Chem. Soc.,
Perkin Trans. 2, 1996, 1581.
[TbL1b].
22 D. Parker and J. A. G. Williams, J. Chem. Soc., Perkin Trans. 2,
1995, 1305.
23 R. S. Dickins, D. Parker, A. S. deSousa and J. A. G. Williams, Chem.
Commun., 1996, 697.
24 D. T. Richens, The Chemistry of Aqua Ions, Wiley, Chichester, 1997,
ch. 3.
25 J. P. Riehl and F. S. Richardson, Methods Enzymol., 1993, 226, 539.
26 D. H. Metcalf, S. W. Snyder, J. N. DeMar and F. S. Richardson,
J. Am. Chem. Soc., 1990, 112, 469.
O
P
O –
H
H
C
Me
N
10H7
N
N
N
Me
O
Tb3+
O –
N
P
O
Me
Me
– O
P
27 E. Huskowska, C. L. Maupin, D. Parker, J. P. Riehl and J. A. G.
Williams, Enantiomer, 1998, in the press.
O
28 Y. Haas and G. Stein, J. Chem. Phys., 1971, 75, 3668.
29 K. Nakamura, Bull. Chem. Soc. Jpn., 1982, 55, 2697.
30 S. R. Meech and D. Phillips, J. Photochem., 1983, 23, 193.
This compound was prepared following a method similar to
that for complex [EuL2] using terbium() acetate (0.071 g, 0.21
mmol) and compound L1b (0.1 g, 0.15 mmol) in water (3 cm3) to
yield a yellow solid (0.08 g, 65%). Characterisation data are the
same as those reported for [TbL1a] (Found: MHϩ, 816.1880.
C28H46N5O7P3Tb requires MHϩ, 816.1863).
Received 2nd December 1997; Paper 7/08667I
892
J. Chem. Soc., Dalton Trans., 1998, Pages 881–892